Arny Krueger wrote:

"Kevin McMurtrie" wrote in message
...
snip
A nearby electronics surplus store is the key.


I live in a large metro area (Detroit) and the last good local electronics
surplus store has been gone for about 20 years.
snip

Was that Silverstein's on the east side?

In article ,
"Arny Krueger" wrote:

"Kevin McMurtrie" wrote in message
...
[snip]
A nearby electronics surplus store is the key.

I live in a large metro area (Detroit) and the last good local electronics
surplus store has been gone for about 20 years. Besides, relying on surplus
is condemning yourself to outdated technology. However since power amps are
a mature technology, that isn't the problem it might be. However, since
power amps are a mature technology, what's to be gained by avoiding finished
products that are often sold for far less than what the parts would cost,
even from a good supplier (not Radio Shack).
[snip]

Maybe you're thinking of an electronics junkyard. The surplus stores
I've seen get parts left over from assembly line prototypes,
discontinued products, and stock from factories that closes down. I
usually find enough modern unused components to build 95% of a project.

"Arny Krueger" wrote in message news:5A6dnS1fBuizjpGiU-


Solid state amplifiers have been around for about 40 years and after 40
years of development, why shouldn't most issues be pretty well settled?


That is because the FTC has never mandated a set of specifications
that tells very well how an amplifier or CD player performs. If the
FTC were to mandate a set of tests (similar to the tests used on your
website) it would eliminate much of the fraud and confusion in the
industry.

For example, a simple two tone test (using 17 KHz and 19 KHz) would
tell much more about the quality of amplifiers and CD players than
the presently used "THD" tests. The potential buyer could simply look
at the level of the second order beat falling at 2 KHz, and of two
third order beats falling at 15 KHz and 21 KHz, to help him determine
which amplifier or CD player had the lower distortion.

The consumer doesn't have much comfidence in the way amplifiers and CD
players are presently tested and specified. That leaves him open to
fraud and hype on the one hand, and to overlooking perfect good (low
cost) products on the other hand. Better tests and specifications
would go a long way toward eliminating fraud, deception, and comsumer
confusion in the audio industry.

Bob Stanton

Bob-Stanton wrote:

"Arny Krueger" wrote in message news:5A6dnS1fBuizjpGiU-



Solid state amplifiers have been around for about 40 years and after 40
years of development, why shouldn't most issues be pretty well settled?



That is because the FTC has never mandated a set of specifications
that tells very well how an amplifier or CD player performs. If the
FTC were to mandate a set of tests (similar to the tests used on your
website) it would eliminate much of the fraud and confusion in the
industry.

I'm not sure the FTC should be doing much more than setting minimal
standards to allow prosecuting false advertising. The IEEE or some
such body seems more appropriate for setting test standards.


For example, a simple two tone test (using 17 KHz and 19 KHz) would
tell much more about the quality of amplifiers and CD players than
the presently used "THD" tests. The potential buyer could simply look
at the level of the second order beat falling at 2 KHz, and of two
third order beats falling at 15 KHz and 21 KHz, to help him determine
which amplifier or CD player had the lower distortion.

The consumer doesn't have much comfidence in the way amplifiers and CD
players are presently tested and specified. That leaves him open to
fraud and hype on the one hand, and to overlooking perfect good (low
cost) products on the other hand. Better tests and specifications
would go a long way toward eliminating fraud, deception, and comsumer
confusion in the audio industry.

I don't think the consumer cares. If he did, I would have thought
manufacturers would satisfy his need as a result of competitive
pressure.


Bob Stanton

Not if you believe Doug Self - try reading his power amp design hand-book.
He has a few designs, which you might use as a basis.

Neil McBride http://www.neilmcbride.co.uk/ has a Naim 135 clone with
layouts. I have built these and they sound pretty good. Cost is way
cheaper than getting them from Naim, especially if you cannibalise an old
amp for tranformer, chassis and caps, which are the most expensive parts.


Andy wrote in message
om...
Hi,
Can someone comment on this amp?

http://www.pha.inecnet.cz/macura/follower_e.html

Seems very simple and elegant. Can I expect good hi-fi sound out
of this? How will it compare, says, to a Hafler DH200?

Thanks
Andy

Andy wrote in message
om...
Hi,
Can someone comment on this amp?

http://www.pha.inecnet.cz/macura/follower_e.html

Seems very simple and elegant. Can I expect good hi-fi sound
out
of this? How will it compare, says, to a Hafler DH200?

It's reasonably simple, but certainly not elegant. It's extremely
inefficient. It has no gain, so you'll probably have to find a
substantial preamplifier just to drive it. It has poor power supply
rejection. It has no feedback (because it has no gain) and this is
listed as an advantage; why, I don't know. It contains a 3.3v zener
diode, which is about as poor as a zener gets.

Since I know nothing about the Hafler DH200, I can't comment reliably
on how it would compare. It's been my experience, however, that
Hafler is a superb designer. I can't imagine him designing anything
as crummy as that Macura design.

Norm Strong

CJT wrote in message
..

I'm not sure the FTC should be doing much more than setting minimal
standards to allow prosecuting false advertising. The IEEE or some
such body seems more appropriate for setting test standards.


I agree. We really don't want the goverment poking around in the audio
industry.

I don't think the consumer cares. If he did, I would have thought
manufacturers would satisfy his need as a result of competitive
pressure.


I agree with that as well.

I don't expect consumers in Wal-Mart, buying a boom-box, to care much
about intermodulation distortion. But, even in this audio group,
people seem to have little interest in what the actual measured
distortion of a product is. For example, I've seen threads on: SACD vs
DVD-A vs CD. There were sometimes hundreds of messages, in the
threads, but no one even mentioned actual *measured* performance of
the various types of systems.

Bob Stanton

I do not know much, but I do know this from 1st hand experience:

Comparison of Sony DA5ES, Rotel RB-980, and a Mark-5 TA-477 (diy amp)

Sony:
Type: 5.1 channel receiver
paid: ~$900 in 2001
Music production: tiny, digital artifacts (breaking up?), high
female voices sounded like a cheap clock radio..
(exaggeratted a bit..)

Rotel:
Type: 2 channel power amp
paid: ~$700 in 1992
Music production: warm, full. sounded good to me.

Mark-5 TA-477:
Type: diy amp.
paid ~$70/channel in 1992 (not including
casing and power supply)
Music production: warm, full. sounded good to me. Sounded the same
as the Rotel... I'm sure there's subtle differences,
but I didn't hear any.

You draw your own conclusions... :-)

Andy

"Arny Krueger" wrote in message
...
....
...
Building power amps and hoping to save money and get superior sound is
futile at this time. If nothing else you now have to contend with the
Chinese who can sell you a finished power amp for less than you will pay at
a good electronics parts place for output devices, heat sink, power
electrolytics and power transformer.

You mentioned the Hafler DH-200. It's a fine amp. There are a number of
DH-200 and DH-220 amps up for auction on eBay right now. Current bid prices
are in the $200 range. You say that you can fix things - if the amp you get
from eBay is a fixer-upper, have fun and save even more money!

If so, can someone point to a source
for a great diy amp? My kit building skill is pretty good.
I can etch my own boards if I have the circuit layout
patterns, but I don't have the skills to do a layout from
scratch.

If it was worth the effort, I'd say do it. But, it isn't. Power amps are a
solved problem - the only thing left for them to do is to get smaller,
cheaper, lighter...

"Bob-Stanton" wrote in message
om...
But, even in this audio group,
people seem to have little interest in what the actual measured
distortion of a product is. For example, I've seen threads on: SACD vs
DVD-A vs CD. There were sometimes hundreds of messages, in the
threads, but no one even mentioned actual *measured* performance of
the various types of systems.

You obviously didn't look too hard then.

Trevor.