"Coconut" wrote in message
oups.com...
Wow - what a minefield this is turning out to be !

As you can probably tell I don't know very much about these things (
hence the reason for coming here to ask for advice ).

If I play music at a "reasonable" volume all is well. If I turn up the
volume to "loudish" then before long the amp will cut out.

Now then, if it is accepted that I AM going to keep the Technics Amp -
old, outdated and low spec. though it is, ( and I do appreciate
everyone's suggestions to get a more up to date decent amp ), then what
I want to do is get the best performance out of its limited spec.

Buy a poweramp!


In a nutshell what would the most appropriate specification of speaker
to use with this amp ( without upsetting the Bank Manager :-) ??

High sensitivty (91dB+) high impedance and high nominal where it doesn't
drop down too much (8Ohm, 6Ohm nominal ) But that doesn't mean they're good
speakers. In fact some of the better speakers are in fact harder to drive
and low sensitivity for some reason. My Kef Reference speakers are 4Ohm, 2.2
Nominal. But I would rather have than Q series which are 6Ohm.


... and here is the full Amp spec as quoted in its manual, which I hope
means more to you than it does to me !
( harrogate 2 - thanks for trying to elighten me but I didn't
understand most of your reply - sorry ).

Power Output ( at 240v )

DIN 1 kHz ( T.H.D. 1% )
2 x 100 W ( 4 ohms )

:-) yep thought so. 1% THD is in clipping area (esp for tweeters) and 1khz
and DIN testing to make it look better, so that 100W figure is meaningless.
If it were retested the actual output (W) into 4Ohm load at far lower normal
THD figure (usually .1% or lower) with the full range signal as well that'll
bring it down, so will DIN figure.

Another way of changing results is to do 8 & 4 ohm testing with different
variables...so test 8 ohm with both channels, 4 ohm with only one channel.
This is because 4ohm strains the PSU more and can trip up badly designed
amps - wink wink - so using a pair of 4 ohm speakers, full range at low THD
will probably be lower than 8ohm testing!! Can't have that! :-)

Another way is to increase THD figures, so if you have two amps..

50W @ 0.05% THD
or 100W @ 10% THD

Which looks better on paper? The 200W to the mass public, as THD confuses
them. MORE POWER IS BETTER! :-)

40 Hz - 20 kHz continuous power output both channels driven
2 x 80 W ( 8 ohms )

Not full range test I see. I wonder why? ;-) No THD figure given either,
only those in the other section..are the two tests of the same?


Total harmonic distortion
rated power at 40 Hz - 20 kHz 0.5% ( 8 ohms )
half power at 1 kHz 0.03% ( 8 ohms )

Ahh half power, another way of making it look better, again 1khz tone as
well!
Again not full range test.

Are the above THD figures results taken from the first tests, or just when
the testers felt their results show the amp in it's best light? :-)

Usually they will test output, but the figures will not match the two. It's
like saying driving down the motorway at 70mph, so "70mph" figure is quoted.
Wow brill! * RPM of the engine is tested say 2500rpm in 5th gear ...only
2500 rpm? That's crap!*

But then another rpm figure is measured when accerlating in a totally
different test(ie 8000rpm) Wow brill!*so they state that 8000rpm result, but
do not mention motorway cruising at 70mph results in 8000rpm (both results
on the same paragraph)

On paper this doesn't seem such a great amp and worthy of keeping it...now
if you had a Mcintosh or 80's Rotel or similar that can be used as a WMD
then that's another matter. Built well...compared to Technics :-)

IMO those tests are meaningless, I could just throw out the 30W approx
figure and it'll most likely be more accurate than their overblown figures.
Check Yamaha lower models proper tests, something like 100W P.C. manu.
published specs but actually only 30-35W P.C.

The crowning jewel of making your figures look great is PMP0. I have a set
of 2500W PMPO PC speakers, and my audio system is 25,000W PMPO!!! :-D
Actually RMS 2.5KW into true RMS, full range, low THD, both channels etc..

*meaning for the mass public kids that look at specs and see more
power=better

Intermomulation distortion
rated power at 60 Hz: 7 kHz-4:1,SMPTE 0.5% ( 8 ohms )

Power bandwidth
both channels driven, -3dB 10 Hz - 40 kHz ( 8 ohms )

Damping Factor 40 ( 8 ohms )

"andy" wrote in message
ups.com...
If I play music at a "reasonable" volume all is well. If I turn up
the
volume to "loudish" then before long the amp will cut out.

Has it always done this? or has it started recently?

Do you want to listen at loudish volumes? or only reasonable volumes?

What exactly do you consider to be wrong with your current
loudspeakers?


There was someone on other forum with exactly the same issue, a low powered
tube amp with low current drive, speakers distorting...no amount of getting
him to try differenct poweramp with beefier output and/PSU made a
difference...instead sold speakers and still it distorts with these easier
to drive speakers!

sigh...

In article .com,
Coconut wrote:
Hi Neth,

Thanks for the advice - I'd prefer to keep the amp ( daft I know but it
has sentimental value ). So if I replaced the speakers with 8ohm ones
they'd be less likely to overload the amp ??

The problem with answering your question is that the relative efficiencies
of the speakers also matters.

If you changed to '8 Ohm' speakers, but they have a significantly lower
efficiency than your current '4 Ohm' ones, then you may simply get the same
problem.

Hence we'd really need to know a lot more details of your current speakers
and amp *and* any replacement to be able to say. Even then, it may be that
the present problem isn't simply current limiting but that your amp
dislikes something specific, or is having some other problem. Hence
predicting the effect of a change in speakers is hard.

Check the efficiency values of any candidates for 'new' speakers. If they
aren't at least similar to your present ones then you might not be any
better off with them.

As Arny has said, the efficiency tends to be given in terms of a 'dB/watt'
value. If the new speakers don't give a higher value than your current
ones, then you may find they don't really help. Note also that the
'dB/watt' values are often misleading as they tend to be measured for a
given voltage, so don't assume that the change in impedance matters unless
the C55 specs say otherwise.

Slainte,

Jim

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

In article .com,
Coconut wrote:
Wow - what a minefield this is turning out to be !

As you can probably tell I don't know very much about these things (
hence the reason for coming here to ask for advice ).

If I play music at a "reasonable" volume all is well. If I turn up the
volume to "loudish" then before long the amp will cut out.

That does not sound to me like current limiting protection which tends to
act more promptly so far as human reaction times are concerned.

It sounds like the amp is simply getting too warm and doing a thermal
shutdown. In effect, your are trying to make it play too loud for too long
for that design. Bigger heatsinks or a fan might help... :-)

Now then, if it is accepted that I AM going to keep the Technics Amp -
old, outdated and low spec. though it is, ( and I do appreciate
everyone's suggestions to get a more up to date decent amp ), then what
I want to do is get the best performance out of its limited spec.

In a nutshell what would the most appropriate specification of speaker
to use with this amp ( without upsetting the Bank Manager :-) ??

High efficiency.

Slainte,

Jim

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

Nath wrote:

There was someone on other forum with exactly the same issue, a low powered
tube amp with low current drive, speakers distorting...no amount of getting
him to try differenct poweramp with beefier output and/PSU made a
difference...instead sold speakers and still it distorts with these easier
to drive speakers!

I put it down to too much mis-information on the importance of speakers
when it comes to sound quality. The media often perpetuates the myth.

A good source and adequate speakers will always perform better than an
adequate source and "better" speakers.

In message , Silk
writes
Nath wrote:

There was someone on other forum with exactly the same issue, a low
powered tube amp with low current drive, speakers distorting...no
amount of getting him to try differenct poweramp with beefier output
and/PSU made a difference...instead sold speakers and still it
distorts with these easier to drive speakers!

I put it down to too much mis-information on the importance of speakers
when it comes to sound quality. The media often perpetuates the myth.

A good source and adequate speakers will always perform better than an
adequate source and "better" speakers.

That's a VERY debatable viewpoint. One that was pushed by Linn and
other charlatans 20 years ago and that I thought had mercifully died out
now.

The speakers dominate the sound produced now, just as much as they did
20 years ago.
--
Chris Morriss

Chris Morriss wrote:

The speakers dominate the sound produced now, just as much as they did
20 years ago.

The logical argument is: Speakers do not produce any sound of their own;
they can only do their best to reproduce what is fed to them. Anyway, my
own listening experience tells me I'm right. Quality speakers are always
desirable, but they will never make up for inadequacies elsewhere.

In message , Silk
writes
Chris Morriss wrote:

The speakers dominate the sound produced now, just as much as they
did 20 years ago.

The logical argument is: Speakers do not produce any sound of their
own; they can only do their best to reproduce what is fed to them.
Anyway, my own listening experience tells me I'm right. Quality
speakers are always desirable, but they will never make up for
inadequacies elsewhere.

If only it were that case that speakers "do not produce sound of their
own". Sadly, all speakers produce some colouration, and in general this
has far more effect on the sound than different amps or CD players.

(Now if you're talking valve amps or vinyl replay devices then it may be
a different can of worms, but I am assuming *most* of us here would
rather not have the replay equipment impose a dominant 'sound signature'
over everything!)
--
Chris Morriss

In article ,
Silk wrote:
The speakers dominate the sound produced now, just as much as they did
20 years ago.

The logical argument is: Speakers do not produce any sound of their own;

Don't be silly. Any resonances they have are the equivalent of producing a
sound of their own. Ever heard of one note bass as an extreme example?

they can only do their best to reproduce what is fed to them. Anyway, my
own listening experience tells me I'm right. Quality speakers are always
desirable, but they will never make up for inadequacies elsewhere.

Nothing can make up for inadequacies elsewhere.

--
*I went to school to become a wit, only got halfway through.

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

On 2005-03-25, Silk wrote:
Chris Morriss wrote:

The speakers dominate the sound produced now, just as much as they did
20 years ago.

The logical argument is: Speakers do not produce any sound of their own;
they can only do their best to reproduce what is fed to them. ...

I believe we can say that all components in an audio system work like
that. Every component in the audio chain has an input, an output and a
system transfer function. The overall sound is made up of the effects
of every component's transfer function.

... Quality speakers are always
desirable, but they will never make up for inadequacies elsewhere.

I think this is true, but it works in all other ways such as "a quality
amplifier is always desirable but will never make up for inadequacies
elsewhere (e.g. in loudspeakers)".

It still seems to me that the imperfections introduced in a complete
audio chain by loudspeakers are greater than the imperfections introduced
in most other places. At least the measured frequency response and
distortion characteristics of loudspeakers seem to be worse than those
of amplifiers for example.

Maybe a transducer such as a pick-up cartridge is as bad or worse but in
a CD system the loudspeakers are almost certainly the audibly dominant
imperfection.

And of course we can also say that however good the system is that we
put in place, it cannot make up for imperfections in the process which
produced our CDs (or LPs, or other sources).

--
John Phillips