Keith G wrote:

For anyone who is interested, there are a few pix of the inside of one of
the new cheap, Chinese amps I have just bought.

http://www.apah69.dsl.pipex.com/keit...chineseamp.htm

The second one arrived with a little rattle inside it which gave me the
excuse to whip the bottom off!

Anyway, I think they are surprisingly good for the price and would be quite
satisfied if I had built one to the same standard myself. (I hope the pix
give sufficient indication.) Note the pound coin on one of the OPTs for
scale - to reassure those here who are ever prepared to condemn without
seeing/hearing......

What did you pay ?

And what's the 4th transformer lurking inside the chassis for ? Just the heaters
? I can just about see 6.3V marked on it.


Graham

If 6F2 is a triode-pentode the circuit must be a lot like the WAD ones, pentode
first into a concertina with feedback wrapped around it. Can't say that's a
choice I'm nuts about. I'd certainly pop in a 6922/6N1P and tweak the circuit
for starters (maybe zero global NFB) or drill out the holes for octal sockets.
One good thing is the layout - looks like there's room to mod it and add
componants. Mind, I tend to get the drill out at the first opportunity.........
Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

In message , Andy Evans
writes
If 6F2 is a triode-pentode the circuit must be a lot like the WAD ones, pentode
first into a concertina with feedback wrapped around it. Can't say that's a
choice I'm nuts about. I'd certainly pop in a 6922/6N1P and tweak the circuit
for starters (maybe zero global NFB) or drill out the holes for octal sockets.
One good thing is the layout - looks like there's room to mod it and add
componants. Mind, I tend to get the drill out at the first opportunity.........
Andy

How would you get an adequately low output impedance with no global NFB,
given that the output is pentode connected?
--
Chris Morriss

How would you get an adequately low output impedance with no global NFB,
given that the output is pentode connected?

Is it pentode or UL? If UL it may work fine. I run my amp in UL without global
NFB - sounds OK. I prefer to let the sound breathe, whatever the beneficial
effects of NFB on distortion. If you use the lowest distortion triodes you can
get hold of in the input stages it certainly helps. Bass is OK for my needs. I
have no need of 'bass slam' - on the contrary I prefer a warmer bass, which
sounds more like the real thing to me. I'm probably hopelessly biased in all
this since I'm a professional double bass player, and as the saying goes "the
cobbler's children have no shoes" Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

"Andy Evans" wrote in message
...
How would you get an adequately low output impedance with no global NFB,
given that the output is pentode connected?

Is it pentode or UL? If UL it may work fine. I run my amp in UL without
global
NFB - sounds OK. I prefer to let the sound breathe, whatever the
beneficial
effects of NFB on distortion. If you use the lowest distortion triodes you
can
get hold of in the input stages it certainly helps. Bass is OK for my
needs. I
have no need of 'bass slam' - on the contrary I prefer a warmer bass,
which
sounds more like the real thing to me. I'm probably hopelessly biased in
all
this since I'm a professional double bass player, and as the saying goes
"the
cobbler's children have no shoes" Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Just wondering..as a pro double bass player who likes the warmer bass
sounds, do you happen to have any particular preference in mics when sound
reinforcement is required for your bass?

Cheers,

Mike

I don't play so much now - I was an active pro for around 20 years. I never
used mics - In jazz terms it's more usual to use a pickup on the bridge of the
bass. I played bebop and post bop mostly (after a classical training). Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

"Andy Evans" wrote in message
...
I don't play so much now - I was an active pro for around 20 years. I never
used mics - In jazz terms it's more usual to use a pickup on the bridge of
the
bass. I played bebop and post bop mostly (after a classical training).
Andy

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

The double bass has such a lovely rich sound that I find the bridge pickups
don't do justice. When recording db I like a nice omni condenser mic,
trouble is thats no good for SR The modern long n' narrow (electric) basses
with DI'd string pickups just don't sound as nice IMO.

There must be some stories to tell being a pro bassist....(leading question
:-)

Mike

In article ,
Mike Gilmour wrote:
Just wondering..as a pro double bass player who likes the warmer bass
sounds, do you happen to have any particular preference in mics when
sound reinforcement is required for your bass?

Since feedback is likely to be a major problem with using a conventional
mic in a decent position, a contact type is usually the best bet.

If you want to try with a proper mic, a U87, etc, takes some beating. Try
it in figure of eight and omni as well as the obvious cardiod.

Sadly, they're very expensive.

A decent half way house is a good small *omni* condenser - normally for
high quality hand mic use (not where high level PA is required). Wrap the
body in foam and insert in an F hole. Calrec and AKG made plenty of these
for TV use which can be bought quite reasonably secondhand. Under 100 quid.

Calrec also made an oddball version which isn't balanced output and
doesn't use phantom, but had its own external 50 volt power supply. Easy
to make one if it's missing. These aren't much sought after, so can be
very cheap. And since really an 'amateur' mic, usually in good condition.
Sound pretty well the same as their pro range.

--
*Horn broken. - Watch for finger.

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

There must be some stories to tell being a pro bassist....(leading question
:-)

It's not specially the bass, but I could write a film about being a jazz
musician (actually - I've written about 15 pages already!)

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

"Nick Gorham" wrote


6F2's are $4 from

http://www.diyhifisupply.com/diyhs_nos_china_tubes.htm


Thanks Nick - 8 of these are on their way to me even as I type (?? ;-) for
only £21+ on Paypal!!

Ya canna beat it, can ya?

:-)