That'll Teach Me... (Chinese Valve Amp)
 

Steve wrote:

I bought a Chinese valve amp (Yaoin 300B job), on Ebay. Like this one:


http://cgi.ebay.co.uk/300B-High-End-...QQcmdZViewItem

It worked great for quite a while and I enjoyed the sound.
Now the left channel has gone dodgy. The music is still barely "there",
but all scratchy and weak. The right channel is fine.
I've swapped leads and connectors to establish that the speakers/cables/CD
player are not at fault. It definitely seems to be the amplifier. The left
output valve doesn't get as hot as the right one. Swapping the valves
indicates that the valve is not the problem.

Can anyone suggest a solution (other than using it as the world's heaviest
paperweight)?

I live in the North West of England. Is there anyone in the region who
could fix it?

Thanks for any help.

Steve

If all else fails, you can use the good channel for karaoke, you won't need
a mic, just sing into the 12AT7 on the front end.

If you get it fixed, do replace the 12AT7s with 12AU7s or 12AX7s

Keith

That'll Teach Me... (Chinese Valve Amp)
 

I bought a Chinese valve amp (Yaoin 300B job), on Ebay. Like this one:

http://cgi.ebay.co.uk/300B-High-End-...QQcmdZViewItem

It worked great for quite a while and I enjoyed the sound.
Now the left channel has gone dodgy. The music is still barely "there", but
all scratchy and weak. The right channel is fine.
I've swapped leads and connectors to establish that the speakers/cables/CD
player are not at fault. It definitely seems to be the amplifier. The left
output valve doesn't get as hot as the right one. Swapping the valves
indicates that the valve is not the problem.

Can anyone suggest a solution (other than using it as the world's heaviest
paperweight)?

I live in the North West of England. Is there anyone in the region who could
fix it?

Thanks for any help.

Steve

That'll Teach Me... (Chinese Valve Amp)
 

Same here dude.

I'm in Manchester, BTW. I bought a YaQin (not Yaoin, BTW) amp back
in summer 2004. Worked a charm and sounded beautiful for a few weeks,
and then BANG! Resistors started burning out, and that caused valves to
have internal firework shows, which caused further overcurrent.

Mine too has always been more of a PITA on the left channel, though
that'll only be coincidence.

Right now, the right-hand channel is fine. The left is ****ed; it just
sounds far too quiet, "scratchy" as you put it, and "early-clippy".

When it works/worked properly, it was like a beautiful, but
high-maintenance girlfriend: Fantastic and "Ooooooh!" but a moody
pain in the ****ing arse a lot of the time, that demands too much attention
when it really should be just cutting the crap and be getting on with letting
us both have a good time. That's the best analogy I can give.

Bummer, but I don't have a 'scope, so I've no real chance of fixing
it, I don't think.

I feel your pain!


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie

That'll Teach Me... (Chinese Valve Amp)
 

"Steve" wrote in message
...
I bought a Chinese valve amp (Yaoin 300B job), on Ebay. Like this one:

http://cgi.ebay.co.uk/300B-High-End-...QQcmdZViewItem

It worked great for quite a while and I enjoyed the sound.
Now the left channel has gone dodgy. The music is still barely "there",
but all scratchy and weak. The right channel is fine.
I've swapped leads and connectors to establish that the speakers/cables/CD
player are not at fault. It definitely seems to be the amplifier. The left
output valve doesn't get as hot as the right one. Swapping the valves
indicates that the valve is not the problem.

Can anyone suggest a solution (other than using it as the world's heaviest
paperweight)?

I live in the North West of England. Is there anyone in the region who
could fix it?

Thanks for any help.


I have fixed quite a few of 'em in the past year. They usually have
simple but sometimes terminal (i.e fatal) faults. They range from
simple dry solder joints, or failed coupling caps, or intermittent
bias pots, to open circuit windings on the OPT.

The are people on RAT (rec.audio.tubes) who will probably been able
to pinpoint the fault from your description and further
discussion. Patrick Turner is especially knowledgeable, but holds
most Chinese products in low esteem. Many of them use poor quality
components and woefully poor/small transformers, which are hidden
inside large impressive-looking pots, sometimes filled with cat litter as a
potting compound.

At least you have one working channel, one which you can take DC
voltage measurements and compare with the broken channel. That's
the fastest way to fault find. But take great care. Even with the amp
switched off and unplugged there can still be high voltages on the
power supply capacitors.

Recently, while in Vietnam - I cam across a tube amp shop in Saigon.
I told the salesman I was interested in buying in quantity, and he offered
me "any ten amplifiers for USD1000" I have a feeling there would
also have been considerable room for negotiation in that price!!

One cannot even buy a proper UK built 300B output transformer
for the price of a complete Chinky amplifier.. Caveat emptor:-)

It's good that people are interested in thermionic audio, but sadly
they may get the wrong impression regarding reliability from a
Chinese-built product.

Tube amps can and should be reliable. I have a friend in Sweden
who is a bespoke amp builder. He offers a ten year warranty on
his work. He has been in business some twenty years, and has never
had amp returned for more than routine service.

Good luck

Iain

That'll Teach Me... (Chinese Valve Amp)
 

Steve wrote:
I bought a Chinese valve amp (Yaoin 300B job), on Ebay. Like this one:

http://cgi.ebay.co.uk/300B-High-End-...QQcmdZViewItem

It worked great for quite a while and I enjoyed the sound.
Now the left channel has gone dodgy. The music is still barely
"there", but all scratchy and weak. The right channel is fine.
I've swapped leads and connectors to establish that the
speakers/cables/CD player are not at fault. It definitely seems to be
the amplifier. The left output valve doesn't get as hot as the right
one. Swapping the valves indicates that the valve is not the problem.

Can anyone suggest a solution (other than using it as the world's
heaviest paperweight)?

I live in the North West of England. Is there anyone in the region
who could fix it?

Thanks for any help.

Steve

I'm in Stockport and restore valve radios as a hobby.
I'd be happy to look at it, and repair it if it's a fairly common component
at fault.
Martin.

That'll Teach Me... (Chinese Valve Amp)
 

My take on Chinese amps is that they are basically kits of parts,
nominally put together in working condition. They're worth it for the
parts - if they are cheap enough after importing. This suits a
competent builder, who can immediately start replacing parts and who
can fault find reasonably well. Something like the equivalent of an un-
reconditioned old Leak amp with leaky caps and out of spec resistors.

But add on the import duty and this comes to over ?700. This buys a
better valve amp on the second-hand market. Like a re-conditioned Leak
for instance. Better? Well, I'd prefer a 300b. But a Leak will hold
its value, is substantially built and can be tweaked to sound really
nice. But there are quite a variety of valve amps about these days,
and I wouldn't be surprised if ?700 would get you a nice Yank amp or a
boutique UK one.

That'll Teach Me... (Chinese Valve Amp)
 

Martin Crossley wrote:


I'm in Stockport and restore valve radios as a hobby.
I'd be happy to look at it, and repair it if it's a fairly common component
at fault.
Martin.




I would guess Stockport is nearer to you, but I am in the general area
of Halifax, if you need any more help.

--
Nick

That'll Teach Me... (Chinese Valve Amp)
 

"Steve" wrote in message
...
I bought a Chinese valve amp (Yaoin 300B job), on Ebay. Like this one:

http://cgi.ebay.co.uk/300B-High-End-...QQcmdZViewItem



Why do you say 'That'll teach me'??

Like you could have bought a Border Patrol 300B amp (say) for anything
upwards of 4K:

http://www.users.globalnet.co.uk/~va...rPatrolAmp.htm

http://www.borderpatrol.co.uk/amprev.htm


....but chose the Chinaman for what - less than 400 quid instead? (You
get what you pay for in this life!! :-)

Anyway, I see you've had a couple of kind offers of help already -
expect to pay for some parts, needless to say...

That'll Teach Me... (Chinese Valve Amp)
 

"Iain Churches" wrote


snip wise words - except the bit about the Sinophobic RATs


One cannot even buy a proper UK built 300B output transformer
for the price of a complete Chinky amplifier.. Caveat emptor:-)

It's good that people are interested in thermionic audio, but sadly
they may get the wrong impression regarding reliability from a
Chinese-built product.

Tube amps can and should be reliable. I have a friend in Sweden
who is a bespoke amp builder. He offers a ten year warranty on
his work. He has been in business some twenty years, and has never
had amp returned for more than routine service.


It's the old ''the Chinky Cheepy you can afford sounds better than the
*audio bling* you can't afford (or don't want to spend the money on)"
argument again, isn't it?

(How long it may *sound* is another matter and the luck of the draw, of
course...! ;-)

That'll Teach Me... (Chinese Valve Amp)
 

Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in fixing the
amp, I've emailed them to arrange a consultation.

Steve



"Steve" wrote in message
...
I bought a Chinese valve amp (Yaoin 300B job), on Ebay. Like this one:

http://cgi.ebay.co.uk/300B-High-End-...QQcmdZViewItem

It worked great for quite a while and I enjoyed the sound.
Now the left channel has gone dodgy. The music is still barely "there",
but all scratchy and weak. The right channel is fine.
I've swapped leads and connectors to establish that the speakers/cables/CD
player are not at fault. It definitely seems to be the amplifier. The left
output valve doesn't get as hot as the right one. Swapping the valves
indicates that the valve is not the problem.

Can anyone suggest a solution (other than using it as the world's heaviest
paperweight)?

I live in the North West of England. Is there anyone in the region who
could fix it?

Thanks for any help.

Steve

That'll Teach Me... (Chinese Valve Amp)
 

"Keith G" wrote in message
...


Why do you say 'That'll teach me'??

Disappointment at the failure, and sick realization that I couldn't really
send it back.
Darned thing sat there looking accusingly at me for months every time I went
into the "office".

Now the offers of help from a couple of the board members has improved my
outlook.


Like you could have bought a Border Patrol 300B amp (say) for anything
upwards of 4K:

http://www.users.globalnet.co.uk/~va...rPatrolAmp.htm

http://www.borderpatrol.co.uk/amprev.htm



No, but I could have bought a used Sugden Class A amp, for example?


...but chose the Chinaman for what - less than 400 quid instead? (You get
what you pay for in this life!! :-)

Anyway, I see you've had a couple of kind offers of help already - expect
to pay for some parts, needless to say...


Yes!

That'll Teach Me... (Chinese Valve Amp)
 

"Steve" wrote in message
...
Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in fixing the
amp, I've emailed them to arrange a consultation.

Steve


You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)

Iain

That'll Teach Me... (Chinese Valve Amp)
 

Iain Churches wrote:
"Steve" wrote in message
...

Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in fixing the
amp, I've emailed them to arrange a consultation.

Steve



You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Hmm, not too keen to do that :-)

http://hi-end.on9mart.com/products/a...8-photo_13.JPG

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)


One of the 680R 50W ali clad wirewounds in the 300b cathodes had gone
open circuit. Should be replaced tomorrow. Clipping in a 1k (didn't have
680R) it all seems to be ok, so think it was just a failed resistor.

I will give it a quick once over once the R is changed, I suspect that
voltages might be a tad high, dur to the mains being 240v at my place. I
notice the same amp has a mention on rat about killing rectifiers. Seems
ok at the moment.

It seems to drive 300bs hard, the good chan had 70v on its cathode,
which makes it 100ma current, and about 400v on the valve, so not for
mesh plates. It might get better with both chans pulling current though.

--
Nick

That'll Teach Me... (Chinese Valve Amp)
 

You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)

Iain


I visited Nick on Sunday. It took him just a few minutes to identify a dodgy
resistor which he is going to replace for me in the next couple of days.

In very good hands indeed.

Steve

That'll Teach Me... (Chinese Valve Amp)
 

Nick Gorham wrote:
Iain Churches wrote:
"Steve" wrote in message
...

Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in
fixing the amp, I've emailed them to arrange a consultation.

Steve



You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Hmm, not too keen to do that :-)

http://hi-end.on9mart.com/products/a...8-photo_13.JPG

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)


One of the 680R 50W ali clad wirewounds in the 300b cathodes had gone
open circuit. Should be replaced tomorrow. Clipping in a 1k (didn't
have 680R) it all seems to be ok, so think it was just a failed
resistor.
I will give it a quick once over once the R is changed, I suspect that
voltages might be a tad high, dur to the mains being 240v at my
place. I notice the same amp has a mention on rat about killing
rectifiers. Seems ok at the moment.

It seems to drive 300bs hard, the good chan had 70v on its cathode,
which makes it 100ma current, and about 400v on the valve, so not
for mesh plates. It might get better with both chans pulling current
though.

Excellent news & work.
It even looks quite well-constructed from the photo.
All the best,
Martin.

That'll Teach Me... (Chinese Valve Amp)
 

"Martin Crossley" wrote in message
...
Nick Gorham wrote:
Iain Churches wrote:
"Steve" wrote in message
...

Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in
fixing the amp, I've emailed them to arrange a consultation.

Steve



You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Hmm, not too keen to do that :-)

http://hi-end.on9mart.com/products/a...8-photo_13.JPG

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)


One of the 680R 50W ali clad wirewounds in the 300b cathodes had gone
open circuit. Should be replaced tomorrow. Clipping in a 1k (didn't
have 680R) it all seems to be ok, so think it was just a failed
resistor.
I will give it a quick once over once the R is changed, I suspect
that
voltages might be a tad high, dur to the mains being 240v at my
place. I notice the same amp has a mention on rat about killing
rectifiers. Seems ok at the moment.

It seems to drive 300bs hard, the good chan had 70v on its cathode,
which makes it 100ma current, and about 400v on the valve, so not
for mesh plates. It might get better with both chans pulling current
though.

Excellent news & work.
It even looks quite well-constructed from the photo.


One thing people seem to overlook is that, disregarding the innards
entirely for the moment, you couldn't get the *casework* for anything
like the price of these amps and I believe this particular amp even
comes with a remote control?

That'll Teach Me... (Chinese Valve Amp)
 

"Nick Gorham" wrote in message
...
Iain Churches wrote:
"Steve" wrote in message
...

Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in fixing
the amp, I've emailed them to arrange a consultation.

Steve



You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Hmm, not too keen to do that :-)

http://hi-end.on9mart.com/products/a...8-photo_13.JPG

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)


One of the 680R 50W ali clad wirewounds in the 300b cathodes had gone
open circuit. Should be replaced tomorrow. Clipping in a 1k (didn't
have 680R) it all seems to be ok, so think it was just a failed
resistor.

I will give it a quick once over once the R is changed, I suspect that
voltages might be a tad high, dur to the mains being 240v at my place.
I notice the same amp has a mention on rat about killing rectifiers.
Seems ok at the moment.

It seems to drive 300bs hard, the good chan had 70v on its cathode,
which makes it 100ma current, and about 400v on the valve, so not
for mesh plates. It might get better with both chans pulling current
though.


I would be interested in your opinion on the *sound quality* when you've
got it bashed into shape, Nick!

That'll Teach Me... (Chinese Valve Amp)
 

"Steve" wrote in message
...

You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)

Iain


I visited Nick on Sunday. It took him just a few minutes to identify a
dodgy
resistor


Jammy sod....

:-)

That'll Teach Me... (Chinese Valve Amp)
 

In article ,
Keith G wrote:
One thing people seem to overlook is that, disregarding the innards
entirely for the moment, you couldn't get the *casework* for anything
like the price of these amps and I believe this particular amp even
comes with a remote control?

Same applies to any mass produced piece of audio gear.

--
*He who dies with the most toys is, nonetheless, dead.

Dave Plowman London SW
To e-mail, change noise into sound.

That'll Teach Me... (Chinese Valve Amp)
 

Keith G wrote:
"Nick Gorham" wrote in message
...

Iain Churches wrote:

"Steve" wrote in message
...


Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in fixing
the amp, I've emailed them to arrange a consultation.

Steve



You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.


Hmm, not too keen to do that :-)

http://hi-end.on9mart.com/products/a...8-photo_13.JPG


Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)


One of the 680R 50W ali clad wirewounds in the 300b cathodes had gone
open circuit. Should be replaced tomorrow. Clipping in a 1k (didn't
have 680R) it all seems to be ok, so think it was just a failed
resistor.

I will give it a quick once over once the R is changed, I suspect that
voltages might be a tad high, dur to the mains being 240v at my place.
I notice the same amp has a mention on rat about killing rectifiers.
Seems ok at the moment.

It seems to drive 300bs hard, the good chan had 70v on its cathode,
which makes it 100ma current, and about 400v on the valve, so not
for mesh plates. It might get better with both chans pulling current
though.



I would be interested in your opinion on the *sound quality* when you've
got it bashed into shape, Nick!





Hopefully that should be tonight. If RS have been as prompt as normal.

--
Nick

That'll Teach Me... (Chinese Valve Amp)
 

Keith G wrote:
"Steve" wrote in message
...

You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)

Iain


I visited Nick on Sunday. It took him just a few minutes to identify a
dodgy
resistor



Jammy sod....

:-)





Yep, that was it, just randomly checking things, and I fell on the fault
entirly by chance.

:-)

--
Nick

That'll Teach Me... (Chinese Valve Amp)
 

"Nick Gorham" wrote in message
...
Keith G wrote:



I would be interested in your opinion on the *sound quality* when
you've got it bashed into shape, Nick!





Hopefully that should be tonight. If RS have been as prompt as normal.



OK, good luck with that then!

I subscribe loosely to the same view as M. Jute that, even if
perceptably *lesser*, the sound from the cheepie chinkies is not that
far behind amps costing as much as ten times the price and that the LODR
kicks in fairly harshly thereafter - my cheapo Bez has certainly held
its own against Ray's Glasshouse number with all the top-of-the-range
'audiophile' bits in it!

That'll Teach Me... (Chinese Valve Amp)
 

"Nick Gorham" wrote in message
...
Keith G wrote:
"Steve" wrote

I visited Nick on Sunday. It took him just a few minutes to identify
a dodgy
resistor



Jammy sod....

:-)


Yep, that was it, just randomly checking things, and I fell on the
fault entirly by chance.


Well you'll be pleased to hear that your email diagnosis/fix on the
Bluebell Audios has held up nicely - I was speaking to Tony on the
blower last night and he tells me they are rock-steady (meters) and
sounding absolutely fine!

That'll Teach Me... (Chinese Valve Amp)
 

"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
One thing people seem to overlook is that, disregarding the innards
entirely for the moment, you couldn't get the *casework* for anything
like the price of these amps and I believe this particular amp even
comes with a remote control?

Same applies to any mass produced piece of audio gear.


True enough - I've lost count of the sodding remote controls here....

:-)

That'll Teach Me... (Chinese Valve Amp)
 

"Keith G" wrote in message
...

"Nick Gorham" wrote in message
...
Iain Churches wrote:
"Steve" wrote in message
...

Thanks to you all for advice/support.

In particular, thanks to Martin and Nick for offers of help in fixing
the amp, I've emailed them to arrange a consultation.

Steve



You seem to be in very good hands, Steve:-)
Try to get one of these two gents to trace out the
circuit for you. It might be useful in the future.

Hmm, not too keen to do that :-)

http://hi-end.on9mart.com/products/a...8-photo_13.JPG

Oh, and come back and tell us how it all
turned out. The whole world loves a happy ending:-)


One of the 680R 50W ali clad wirewounds in the 300b cathodes had gone
open circuit. Should be replaced tomorrow. Clipping in a 1k (didn't have
680R) it all seems to be ok, so think it was just a failed resistor.

I will give it a quick once over once the R is changed, I suspect that
voltages might be a tad high, dur to the mains being 240v at my place. I
notice the same amp has a mention on rat about killing rectifiers. Seems
ok at the moment.

It seems to drive 300bs hard, the good chan had 70v on its cathode, which
makes it 100ma current, and about 400v on the valve, so not for mesh
plates. It might get better with both chans pulling current though.


I would be interested in your opinion on the *sound quality* when you've
got it bashed into shape, Nick!





Me too, Nick!

Steve

That'll Teach Me... (Chinese Valve Amp)
 

Keith G wrote:
"Nick Gorham" wrote in message
...

Keith G wrote:




I would be interested in your opinion on the *sound quality* when
you've got it bashed into shape, Nick!





Hopefully that should be tonight. If RS have been as prompt as normal.




OK, good luck with that then!

I subscribe loosely to the same view as M. Jute that, even if
perceptably *lesser*, the sound from the cheepie chinkies is not that
far behind amps costing as much as ten times the price and that the LODR
kicks in fairly harshly thereafter - my cheapo Bez has certainly held
its own against Ray's Glasshouse number with all the top-of-the-range
'audiophile' bits in it!




Hmm, well, to me thats saying it doesn't matter what it sounds like. To
my mind phrases like "not that far behind" and "LODR kicks in" is
missing the point. I don't (and never have been able to) see how you can
try and "measure" the subjective difference between the sound of two
amps and try and decide the distance per pound metric, and then invent a
notional DPP value below which its not worth continuing.

The amp in question measures ok, I haven't done any great amount of
objective testing other than it seems to have -3dB points about 20hZ and
40kHz at 1w output, and square waves have a good enough leading edge,
with a bit of damped ringing, say about 4 cycles of what looks about 60kHz.

The biggest problem I can see, is like other Chineese amps I have seen,
this one is designed for 220v mains, on the back it says as much, 220v
+- 10%, so that just covers the 240v mains I have here. AFAIK, the
current UK mains voltage spec is 230V +10%, -6%, so even if thats
adhered to, it could be 6% above what this amp is designed for.

But more important IMHO in this case, is the fillament supply for the
valves, at 220v in, the 300b is seeing spot on 5v, but my 240 gives (of
course) 5.5v on the fillament, this is just too high IMHO, and I
certainly wouldn't suggest putting WE 300b's in it.

The second thing that the meter found, was with one chan not pulling
current the B+ on that chan was over 500v, and the other about 470. With
both pulling current, the B+ dropped to about 430v, and the 680R cathode
resistor was passing just over 100ma, so the valve was disapaiting about
36w which is ok.

It does point to poor regulation of the B+ supply though.

I was unsure just what to say about the subjective sound, its not my
amp, it doesn't have to live up to my requirements, so my views actually
have little merit, but as Steve has asked for an opinion, I will give it.

As far as it goes, it sounds ok, no obvious buzzes (a little hum with
94dB/W/m speakers but it sounds like a clean 100hz, no extra harmonics).
It makes sounds. The general sound isn't the most dynamic I have heard,
but I think thats a bit of a 300b quality when compaired to (say 2a3s
amd PX4s), part of that is the top end is ok, but hasn't the crystal
clear quality that can be had from SET's (though I havn't heard a
commercial one that does that, so maybe its not that common), bass
extension is also ok, but the bass doesn't play that many tunes, and
this is with speakers that present a easy load. Again, I am maybe not
being entirly fair with it, as again I am compairing it against the best
DIY amps I have heard.

The biggest problem I have with it, and this is what to my ears makes
its low price of no importance (sorry Steve, you did ask), it doesn't
seem capable of reproducing music. I am not sure how to describe what
its lacking, and I am not sure how it relates to the terms the mags use
to describe stuff, but what it does is make all the noises that were on
the recording, but somehow, doesn't assemble then in the correct order
to make it sound like music, hard to describe, I think its a lot to do
with the quality of the power supply, I think the lack of a solid B+
voltage means that the dynamic bits are interfeering, so all the leading
edges of the sounds are getting in the way of each other, so it just
sounds like the musicians are not listening to each other, and not
playing in sync, just near but not on the pulse of the music.

Its not just this amp that has this problem, I should say, but for me,
its what made me want to stop using the amp after about a hour. So for
my ears it doesn't do what I would expect an amplifier to do, so it just
doesn't cut it.

It may be that with less dynamic material it would be fine (I was mostly
listening to the Jaco Pastorious solo recording).

In fact, if this was the only SET I had heard, I would be happy to agree
with the description of their shortcommings that some of the more
commercially trained EEs on the NG mention every time the topology is
discussed.

I suspect that I am being rather excessivly crytical of the amp, and
perhaps the above should be viewed in that light, but I can only apply
the same standards I apply to amps I might build myself, or listen to
that others have built. If I don't at least try and have a standard to
compare against, then it makes any attempt to build something that at
least does what I want (even if its not to anyone elses liking) will
never have a hope of success.

There you go, just my 2d worth.

--
Nick

That'll Teach Me... (Chinese Valve Amp)
 

"Nick Gorham" wrote in message
. uk...
Keith G wrote:
"Nick Gorham" wrote in message
...

Keith G wrote:




I would be interested in your opinion on the *sound quality* when you've
got it bashed into shape, Nick!





Hopefully that should be tonight. If RS have been as prompt as normal.




OK, good luck with that then!

I subscribe loosely to the same view as M. Jute that, even if perceptably
*lesser*, the sound from the cheepie chinkies is not that far behind amps
costing as much as ten times the price and that the LODR kicks in fairly
harshly thereafter - my cheapo Bez has certainly held its own against
Ray's Glasshouse number with all the top-of-the-range 'audiophile' bits
in it!




Hmm, well, to me thats saying it doesn't matter what it sounds like. To my
mind phrases like "not that far behind" and "LODR kicks in" is missing the
point. I don't (and never have been able to) see how you can try and
"measure" the subjective difference between the sound of two amps and try
and decide the distance per pound metric, and then invent a notional DPP
value below which its not worth continuing.

The amp in question measures ok, I haven't done any great amount of
objective testing other than it seems to have -3dB points about 20hZ and
40kHz at 1w output, and square waves have a good enough leading edge, with
a bit of damped ringing, say about 4 cycles of what looks about 60kHz.

The biggest problem I can see, is like other Chineese amps I have seen,
this one is designed for 220v mains, on the back it says as much, 220v +-
10%, so that just covers the 240v mains I have here. AFAIK, the current UK
mains voltage spec is 230V +10%, -6%, so even if thats adhered to, it
could be 6% above what this amp is designed for.

But more important IMHO in this case, is the fillament supply for the
valves, at 220v in, the 300b is seeing spot on 5v, but my 240 gives (of
course) 5.5v on the fillament, this is just too high IMHO, and I certainly
wouldn't suggest putting WE 300b's in it.

The second thing that the meter found, was with one chan not pulling
current the B+ on that chan was over 500v, and the other about 470. With
both pulling current, the B+ dropped to about 430v, and the 680R cathode
resistor was passing just over 100ma, so the valve was disapaiting about
36w which is ok.

It does point to poor regulation of the B+ supply though.

I was unsure just what to say about the subjective sound, its not my amp,
it doesn't have to live up to my requirements, so my views actually have
little merit, but as Steve has asked for an opinion, I will give it.

As far as it goes, it sounds ok, no obvious buzzes (a little hum with
94dB/W/m speakers but it sounds like a clean 100hz, no extra harmonics).
It makes sounds. The general sound isn't the most dynamic I have heard,
but I think thats a bit of a 300b quality when compaired to (say 2a3s amd
PX4s), part of that is the top end is ok, but hasn't the crystal clear
quality that can be had from SET's (though I havn't heard a commercial one
that does that, so maybe its not that common), bass extension is also ok,
but the bass doesn't play that many tunes, and this is with speakers that
present a easy load. Again, I am maybe not being entirly fair with it, as
again I am compairing it against the best DIY amps I have heard.

The biggest problem I have with it, and this is what to my ears makes its
low price of no importance (sorry Steve, you did ask), it doesn't seem
capable of reproducing music. I am not sure how to describe what its
lacking, and I am not sure how it relates to the terms the mags use to
describe stuff, but what it does is make all the noises that were on the
recording, but somehow, doesn't assemble then in the correct order to make
it sound like music, hard to describe, I think its a lot to do with the
quality of the power supply, I think the lack of a solid B+ voltage means
that the dynamic bits are interfeering, so all the leading edges of the
sounds are getting in the way of each other, so it just sounds like the
musicians are not listening to each other, and not playing in sync, just
near but not on the pulse of the music.

Its not just this amp that has this problem, I should say, but for me, its
what made me want to stop using the amp after about a hour. So for my ears
it doesn't do what I would expect an amplifier to do, so it just doesn't
cut it.

It may be that with less dynamic material it would be fine (I was mostly
listening to the Jaco Pastorious solo recording).

In fact, if this was the only SET I had heard, I would be happy to agree
with the description of their shortcommings that some of the more
commercially trained EEs on the NG mention every time the topology is
discussed.

I suspect that I am being rather excessivly crytical of the amp, and
perhaps the above should be viewed in that light, but I can only apply the
same standards I apply to amps I might build myself, or listen to that
others have built. If I don't at least try and have a standard to compare
against, then it makes any attempt to build something that at least does
what I want (even if its not to anyone elses liking) will never have a
hope of success.

There you go, just my 2d worth.

--
Nick

What amuses me /irritates in equal measure about all the above is that even
staying with valves, a PPUL EL84 amplifier like the Mullard 5-10 or GEC
equivalent has a little more power than the SET, with a whole lot less
distortion and lower output impedance such that is *does* make music very
satisfactorily, without having to make apologies for the SETs shortcomings.
It would also be cheaper to build as a PP output transformer is considerably
cheaper than a half-decent SET one, and a pair of EL84s cost much less than
a single 300B. The only thing I can think of in a SETs favour is that it
looks a lot more dramatic with those DH big triodes.

S.

--
http://audiopages.googlepages.com

That'll Teach Me... (Chinese Valve Amp)
 

Serge Auckland wrote:


What amuses me /irritates in equal measure about all the above is that even
staying with valves, a PPUL EL84 amplifier like the Mullard 5-10 or GEC
equivalent has a little more power than the SET, with a whole lot less
distortion and lower output impedance such that is *does* make music very
satisfactorily, without having to make apologies for the SETs shortcomings.
It would also be cheaper to build as a PP output transformer is considerably
cheaper than a half-decent SET one, and a pair of EL84s cost much less than
a single 300B. The only thing I can think of in a SETs favour is that it
looks a lot more dramatic with those DH big triodes.

S.


Fine, I didn't set out to amuse or irritate you, but if it does, then
thats not my problem.

I was asked by two people on the ng to post what I thought of the sound
of the amp in question, one being its owner, I did so because of that, I
wouldn't have done so otherwise. Especially as I could have (and still
might have) offended the amps owner.

I don't think at any point I made any apologies for anything's
shortcomings, I just posted my own subjective impressions. I made a
point of specifically describing them as subjective, and being my own.

But somehow, this upsets you enough to feel the need to spout a bunch of
unasked for, unconnected and rather condecending opinions.

Hey, when the owner first asked for help, maybe you should have
suggested he send the thing to the tip, and not to consider that it
could be fixed by replacing a £3 resistor.

I am sure you have saved many of the worlds population from being
corrupted by the existance of certain output device and topology.

--
Nick

That'll Teach Me... (Chinese Valve Amp)
 

"Nick Gorham" wrote in message
. uk...
Keith G wrote:


I subscribe loosely to the same view as M. Jute that, even if
perceptably *lesser*, the sound from the cheepie chinkies is not that
far behind amps costing as much as ten times the price and that the
LODR kicks in fairly harshly thereafter - my cheapo Bez has certainly
held its own against Ray's Glasshouse number with all the
top-of-the-range 'audiophile' bits in it!




Hmm, well, to me thats saying it doesn't matter what it sounds like.
To my mind phrases like "not that far behind" and "LODR kicks in" is
missing the point. I don't (and never have been able to) see how you
can try and "measure" the subjective difference between the sound of
two amps and try and decide the distance per pound metric, and then
invent a notional DPP value below which its not worth continuing.



No, it's simpler than that (AFAIAC) - an item is either worth bothering
with or it isn't (at any price) and if it is, spending more on a
'better' version of that item is either worthwhile or it is isn't. It's
a highly subjective/personal thing - Rolex vs. Timex, if you like...


snip interesting review which was pretty much what I expected


I suspect that I am being rather excessivly crytical of the amp, and
perhaps the above should be viewed in that light, but I can only apply
the same standards I apply to amps I might build myself, or listen to
that others have built. If I don't at least try and have a standard to
compare against, then it makes any attempt to build something that at
least does what I want (even if its not to anyone elses liking) will
never have a hope of success.

There you go, just my 2d worth.


Thank you for that. The reason I asked is that the much-mentioned Tony
asked me about the very same amp (on eBay for not a lot, at the time)
and I said that it would likely be OK, may well need some TLC at some
stage and that he might do better to spend a bit more money on summat
that was less 'on the outside' and a little more 'on the inside' (or on
top, in the case of valve amps) - is how he came to buy the Bluebell
300B SET monos!

Note to Steve:

Bear in mind that Nick is a highly experienced *valvie* who has pushed
himself much further into the art than many of us could (or would want)
to go - asking him for an opinion on any cheap amp is never going to get
the reaction 'Cor, I wish I had bought one of these instead!!' My own
*general* opinion of Chinese cheepies remains the same - better *any*
amp you can afford, providing it's at least 'OK', than not having one at
all because you can't afford it or don't want to part with the money!!
They at least get you into the game and, if it proves to be the right
way to go, there's nothing to stop you upgrading at any time in the
future - I'm doing this with mics atm, myself!

That'll Teach Me... (Chinese Valve Amp)
 

"Serge Auckland" wrote


What amuses me /irritates in equal measure about all the above is that
even staying with valves, a PPUL EL84 amplifier like the Mullard 5-10
or GEC equivalent has a little more power than the SET, with a whole
lot less distortion and lower output impedance such that is *does*
make music very satisfactorily, without having to make apologies for
the SETs shortcomings. It would also be cheaper to build as a PP
output transformer is considerably cheaper than a half-decent SET one,
and a pair of EL84s cost much less than a single 300B. The only thing
I can think of in a SETs favour is that it looks a lot more dramatic
with those DH big triodes.


What bothers me with what you say Serge is how much your visit here may
have coloured your opinion of SETs. Apart from the fact I only have a
cheepie Chinkie and a homebrew here, I wasn't too well 'speakered'
then - the Jerichos with the Visaton drivers you heard (as did Nick, the
last time he was here) and Lowther EX3s I tried in them some time after
your visit never did come right and now dwell in my garage until I can
get creative with them. The Fidelios I have now (with lesser Lowther
units in them) are streets ahead in every respect.

(Factor in the secondary system with the 'blameless' Technics pre/power
MOSFET combo you appraised 'on paper' for me playing into the TLS80s I
now have and I reckon I could keep most people happy, one way or
another! :-)

That'll Teach Me... (Chinese Valve Amp)
 

"Nick Gorham" wrote in message
. uk...
Serge Auckland wrote:


What amuses me /irritates in equal measure about all the above is
that even staying with valves, a PPUL EL84 amplifier like the Mullard
5-10 or GEC equivalent has a little more power than the SET, with a
whole lot less distortion and lower output impedance such that is
*does* make music very satisfactorily, without having to make
apologies for the SETs shortcomings. It would also be cheaper to
build as a PP output transformer is considerably cheaper than a
half-decent SET one, and a pair of EL84s cost much less than a single
300B. The only thing I can think of in a SETs favour is that it looks
a lot more dramatic with those DH big triodes.

S.


Fine, I didn't set out to amuse or irritate you, but if it does, then
thats not my problem.

I was asked by two people on the ng to post what I thought of the
sound of the amp in question, one being its owner, I did so because of
that, I wouldn't have done so otherwise. Especially as I could have
(and still might have) offended the amps owner.

I don't think at any point I made any apologies for anything's
shortcomings, I just posted my own subjective impressions. I made a
point of specifically describing them as subjective, and being my own.

But somehow, this upsets you enough to feel the need to spout a bunch
of unasked for, unconnected and rather condecending opinions.

Hey, when the owner first asked for help, maybe you should have
suggested he send the thing to the tip, and not to consider that it
could be fixed by replacing a £3 resistor.

I am sure you have saved many of the worlds population from being
corrupted by the existance of certain output device and topology.


See my reply to Serge - I'm hoping the Jerichos that you heard here
didn't go too far to put him off SETs. As you may remember, the 2A3 SET
(without preamplification) was working far too hard to get a truly
decent sound out of them - totally different story on the Lowthers now,
but then I usually supply it with a nice, phat (but clean) preamplified
signal from the Technics SS Control Amp I have here...

That'll Teach Me... (Chinese Valve Amp)
 

"Nick Gorham" wrote in message
. uk...
Serge Auckland wrote:


What amuses me /irritates in equal measure about all the above is that
even staying with valves, a PPUL EL84 amplifier like the Mullard 5-10 or
GEC equivalent has a little more power than the SET, with a whole lot
less distortion and lower output impedance such that is *does* make music
very satisfactorily, without having to make apologies for the SETs
shortcomings. It would also be cheaper to build as a PP output
transformer is considerably cheaper than a half-decent SET one, and a
pair of EL84s cost much less than a single 300B. The only thing I can
think of in a SETs favour is that it looks a lot more dramatic with those
DH big triodes.

S.


Fine, I didn't set out to amuse or irritate you, but if it does, then
thats not my problem.

I was asked by two people on the ng to post what I thought of the sound of
the amp in question, one being its owner, I did so because of that, I
wouldn't have done so otherwise. Especially as I could have (and still
might have) offended the amps owner.

I don't think at any point I made any apologies for anything's
shortcomings, I just posted my own subjective impressions. I made a point
of specifically describing them as subjective, and being my own.

But somehow, this upsets you enough to feel the need to spout a bunch of
unasked for, unconnected and rather condecending opinions.

Hey, when the owner first asked for help, maybe you should have suggested
he send the thing to the tip, and not to consider that it could be fixed
by replacing a £3 resistor.

I am sure you have saved many of the worlds population from being
corrupted by the existance of certain output device and topology.

--
Nick

Nick, I wasn't getting at you, and I apologise if I gave that impression. I
*was* getting at the current fad for SET amplifiers which were abandoned in
the early part of the last century when PP amplifiers were developed,
overcoming many of the shortcomings of SETs. Why some people persist with
this technology is quite beyond me, other than the same reason some like to
drive vintage MGs, for the sheer fun of it.

SETs have much higher distortion and output impedance than PP amps,
especially those with overall negative feedback. Now, if one likes the sound
of distortion, together with a frequency response that varies with the load,
that's fine, but I would have thought that as alternatives with better
performance are available, it would be better to go that way rather than
persist with something patently flawed.

As to the OP's original problem, it was good that you were able to help, I
would have done the same if he had been local to me. I just wonder why he
was in that position in the first place.

S.

--
http://audiopages.googlepages.com

That'll Teach Me... (Chinese Valve Amp)
 

I suspect that I am being rather excessivly crytical of the amp, and
perhaps the above should be viewed in that light, but I can only apply
the same standards I apply to amps I might build myself, or listen to
that others have built. If I don't at least try and have a standard to
compare against, then it makes any attempt to build something that at
least does what I want (even if its not to anyone elses liking) will
never have a hope of success.

There you go, just my 2d worth.


Thank you for that. The reason I asked is that the much-mentioned Tony
asked me about the very same amp (on eBay for not a lot, at the time) and
I said that it would likely be OK, may well need some TLC at some stage
and that he might do better to spend a bit more money on summat that was
less 'on the outside' and a little more 'on the inside' (or on top, in the
case of valve amps) - is how he came to buy the Bluebell 300B SET monos!

Note to Steve:

Bear in mind that Nick is a highly experienced *valvie* who has pushed
himself much further into the art than many of us could (or would want) to
go - asking him for an opinion on any cheap amp is never going to get the
reaction 'Cor, I wish I had bought one of these instead!!' My own
*general* opinion of Chinese cheepies remains the same - better *any* amp
you can afford, providing it's at least 'OK', than not having one at all
because you can't afford it or don't want to part with the money!! They at
least get you into the game and, if it proves to be the right way to go,
there's nothing to stop you upgrading at any time in the future - I'm
doing this with mics atm, myself!




Chaps,

I'm not the least upset by Nick's comments. Of course I wish he had said
"I'm selling all my custom made gear and sending a cheque off to China
tonight", but it wasn't likely to happen.
In comparison to Nick's thoroughly developed amps and his OB speakers,
average was about the best I could expect.

Now when I get the amp back home on Friday, and attach it to my temporary
(for the last 12 years...) Ruark Templar speakers, I'm confident I will
quickly be back listening to the music and forgetting the equipment
compromises.

I'll let you know.

Steve

That'll Teach Me... (Chinese Valve Amp)
 

In article , Serge Auckland
wrote:

[big snip]

I *was* getting at the current fad for SET amplifiers which were
abandoned in the early part of the last century when PP amplifiers were
developed, overcoming many of the shortcomings of SETs. Why some people
persist with this technology is quite beyond me, other than the same
reason some like to drive vintage MGs, for the sheer fun of it.

SETs have much higher distortion and output impedance than PP amps,
especially those with overall negative feedback.

Coincidentally, I've recently added

http://www.audiomisc.co.uk/outoftune/outoftune.html

to my Audiomisc site. :-)

Didn't include o/p impedance or transformer nonlinearity effects, though.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html