Paul Dormer wrote:
For the uninitiated, the Gaincard is a simplistic amplifier produced
by 47 Laboratory, which at it's heart uses apparently mundane National
Semiconductor's IC opamps. The DIY fraternaty reverse engineered the
Gaincard and now *hundreds* of people worldwide are building Gaincard
clones or modifications thereof, referred to as Gainclones.

I have now read a few reviews of these amps and, for the most part, it
seems reviewers have *transandental* experiences with them.

Comments..?

Have you a link to any information ?



--
Dave xxxx
www.davewhitter.myby.co.uk

Music is Art - Audio is Engineering
Steam is Fun

"Dave xxxxx" wrote in message
...
Paul Dormer wrote:
For the uninitiated, the Gaincard is a simplistic amplifier produced
by 47 Laboratory, which at it's heart uses apparently mundane National
Semiconductor's IC opamps. The DIY fraternaty reverse engineered the
Gaincard and now *hundreds* of people worldwide are building Gaincard
clones or modifications thereof, referred to as Gainclones.

I have now read a few reviews of these amps and, for the most part, it
seems reviewers have *transandental* experiences with them.

Comments..?

Have you a link to any information ?



--
Dave xxxx
www.davewhitter.myby.co.uk

Music is Art - Audio is Engineering
Steam is Fun

Dear Paul and Dave,

The first bit is for you Paul and the second for Dave I do hope you don't
mind me combining the replies.

I agree with your comments about the Gaincard reviews they are over the top
:-)

Since the amp costs very little to make and you can make a Shigaraki clone
using a single cheap transformer, as 47 Labs do, why not make one yourself,
try it and report here on your findings.

A sensible review from someone with an impeccable sound engineering
background who is also an audio enthusiast can be found here;
http://www.mhennessy.f9.co.uk/gainclone/

Gainclone forum;
http://gainclone.com/phpBB2/viewforum.php?f=2

Instructions for anyone unfamilier with components;
http://www.decdun.fsnet.co.uk/gainclone.html#top1

Typing Gaincard and Gainclone into Google will return heaps of reviews,
information and links to friendly forums and helpful builders.

Jem

"Jem Raid" wrote in message


A sensible review from someone with an impeccable sound engineering
background who is also an audio enthusiast can be found here;
http://www.mhennessy.f9.co.uk/gainclone/

Just another tweako-freako with no technical substance.

Here's something with a little more meat:

http://www.stereophile.com/amplifica...47/index4.html

In message , Dave xxxxx
writes
Paul Dormer wrote:
For the uninitiated, the Gaincard is a simplistic amplifier produced
by 47 Laboratory, which at it's heart uses apparently mundane National
Semiconductor's IC opamps. The DIY fraternaty reverse engineered the
Gaincard and now *hundreds* of people worldwide are building Gaincard
clones or modifications thereof, referred to as Gainclones.

I have now read a few reviews of these amps and, for the most part, it
seems reviewers have *transandental* experiences with them.

Comments..?

Have you a link to any information ?



--
Dave xxxx
www.davewhitter.myby.co.uk

Music is Art - Audio is Engineering
Steam is Fun







An LM3875 makes a useful little amp. It's basically a power op-amp with
just the five active pins, so it's easy to wire up a neat design.

I've got a three channel LM3875 amp I built to try out active crossover
networks to drive the bass, middle and tweeter of speakers. I've used
stabilised +/- 35V rails and it sounds and measures pretty well.

(Actually, the wiring structure is important, I've heard of marginally
stable 3875 amps where people don't know how to return signals to the 0v
line in the right place.)
--
Chris Morriss

"Chris Morriss" wrote in message


An LM3875 makes a useful little amp. It's basically a power op-amp
with just the five active pins, so it's easy to wire up a neat design.

I've got a three channel LM3875 amp I built to try out active
crossover networks to drive the bass, middle and tweeter of speakers.
I've used stabilised +/- 35V rails and it sounds and measures pretty
well.
(Actually, the wiring structure is important, I've heard of marginally
stable 3875 amps where people don't know how to return signals to the
0v line in the right place.)

The latest version of this part appears to be the LM4780 - reference
http://www.national.com/ds/LM/LM4780.pdf


http://www.national.com/whatsnew/ind...=779&v=c&p=120 shows a number
of forms of the LM3875 device listed as being "Obsolete".

On Tue, 17 Aug 2004 23:13:16 -0400, "Arny Krueger"
wrote:

"Chris Morriss" wrote in message


An LM3875 makes a useful little amp. It's basically a power op-amp
with just the five active pins, so it's easy to wire up a neat design.

I've got a three channel LM3875 amp I built to try out active
crossover networks to drive the bass, middle and tweeter of speakers.
I've used stabilised +/- 35V rails and it sounds and measures pretty
well.
(Actually, the wiring structure is important, I've heard of marginally
stable 3875 amps where people don't know how to return signals to the
0v line in the right place.)

The latest version of this part appears to be the LM4780 - reference
http://www.national.com/ds/LM/LM4780.pdf

Note that *with careful PSU design*, this amplifier is capable of
being made into a low-cost 'monobloc' using parallel operation, which
will equal or exceed the performance of any 'high end' 50 watt
amplifier. As the excellent article by Hennessy notes (as do the
application notes in the data sheet above), it is absolutely critical
to get the PSU design and layout correct. It's just good basic 'star
earth' engineering practice, but it *is* important.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

In article , Stewart
Pinkerton writes
On Tue, 17 Aug 2004 23:13:16 -0400, "Arny Krueger"
wrote:

"Chris Morriss" wrote in message


An LM3875 makes a useful little amp. It's basically a power op-amp
with just the five active pins, so it's easy to wire up a neat design.

I've got a three channel LM3875 amp I built to try out active
crossover networks to drive the bass, middle and tweeter of speakers.
I've used stabilised +/- 35V rails and it sounds and measures pretty
well.
(Actually, the wiring structure is important, I've heard of marginally
stable 3875 amps where people don't know how to return signals to the
0v line in the right place.)

The latest version of this part appears to be the LM4780 - reference
http://www.national.com/ds/LM/LM4780.pdf

Note that *with careful PSU design*, this amplifier is capable of
being made into a low-cost 'monobloc' using parallel operation, which
will equal or exceed the performance of any 'high end' 50 watt
amplifier. As the excellent article by Hennessy notes (as do the
application notes in the data sheet above), it is absolutely critical
to get the PSU design and layout correct. It's just good basic 'star
earth' engineering practice, but it *is* important.

Car batteries with 2 to 4 farad capacitors and lumps of Furze lightning
conductor to bond it all together with)
--
Tony Sayer

"Stewart Pinkerton" wrote in message

On Tue, 17 Aug 2004 23:13:16 -0400, "Arny Krueger"
wrote:

"Chris Morriss" wrote in message


An LM3875 makes a useful little amp. It's basically a power op-amp
with just the five active pins, so it's easy to wire up a neat
design.

I've got a three channel LM3875 amp I built to try out active
crossover networks to drive the bass, middle and tweeter of
speakers. I've used stabilised +/- 35V rails and it sounds and
measures pretty well.
(Actually, the wiring structure is important, I've heard of
marginally stable 3875 amps where people don't know how to return
signals to the 0v line in the right place.)

The latest version of this part appears to be the LM4780 - reference
http://www.national.com/ds/LM/LM4780.pdf

Note that *with careful PSU design*, this amplifier is capable of
being made into a low-cost 'monobloc' using parallel operation, which
will equal or exceed the performance of any 'high end' 50 watt
amplifier.

The Stereophile review does not seem to support this claim. Nor do the spec
sheets. Many power amps, even the so-called PA Amps that golden ear
audiophiles like to despise have far better performance, an order of
magnitude lower nonlinear distortion at decent power levels, for example.

As the excellent article by Hennessy notes (as do the
application notes in the data sheet above), it is absolutely critical
to get the PSU design and layout correct.

It seems pretty clear that he didn't.

"Unfortunately, because of this, low-level 100Hz charging pulses find their
way onto the output when the two amplifier channels are connected together
(by the preamp). "

His circuit card design varies significantly from the National "reference
design" posted at http://www.national.com/ds/LM/LM4780.pdf page 22.

It's just good basic 'star earth' engineering practice, but it *is*
important.

I agree that power supply circuit card design is important, as I've debugged
that area of some commerical designs. You also have to be careful how you
pick off the feedback path, as I've corrected that in some commercial
designs.

On Wed, 18 Aug 2004 05:49:41 -0400, "Arny Krueger"
wrote:

"Stewart Pinkerton" wrote in message

On Tue, 17 Aug 2004 23:13:16 -0400, "Arny Krueger"
wrote:

"Chris Morriss" wrote in message


An LM3875 makes a useful little amp. It's basically a power op-amp
with just the five active pins, so it's easy to wire up a neat
design.

I've got a three channel LM3875 amp I built to try out active
crossover networks to drive the bass, middle and tweeter of
speakers. I've used stabilised +/- 35V rails and it sounds and
measures pretty well.
(Actually, the wiring structure is important, I've heard of
marginally stable 3875 amps where people don't know how to return
signals to the 0v line in the right place.)

The latest version of this part appears to be the LM4780 - reference
http://www.national.com/ds/LM/LM4780.pdf

Note that *with careful PSU design*, this amplifier is capable of
being made into a low-cost 'monobloc' using parallel operation, which
will equal or exceed the performance of any 'high end' 50 watt
amplifier.

The Stereophile review does not seem to support this claim. Nor do the spec
sheets. Many power amps, even the so-called PA Amps that golden ear
audiophiles like to despise have far better performance, an order of
magnitude lower nonlinear distortion at decent power levels, for example.

That's why I specified 'high end'power amps.....................

As the excellent article by Hennessy notes (as do the
application notes in the data sheet above), it is absolutely critical
to get the PSU design and layout correct.

It seems pretty clear that he didn't.

"Unfortunately, because of this, low-level 100Hz charging pulses find their
way onto the output when the two amplifier channels are connected together
(by the preamp). "

His circuit card design varies significantly from the National "reference
design" posted at http://www.national.com/ds/LM/LM4780.pdf page 22.

Quite so, and he notes the problems............. :-)

It's just good basic 'star earth' engineering practice, but it *is*
important.

I agree that power supply circuit card design is important, as I've debugged
that area of some commerical designs. You also have to be careful how you
pick off the feedback path, as I've corrected that in some commercial
designs.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

In article , Chris Morriss
wrote:


(Actually, the wiring structure is important, I've heard of marginally
stable 3875 amps where people don't know how to return signals to the 0v
line in the right place.)

Not commenting specifically here on the 'gainclone' or 3875. However where
amplifiers have a lot of gain extending to HF you may find that the details
of all the looming of the wires may be critical to control both stability
and distortion. For this kind of reason, I'd be wary of recommending to
those without suitable HF kit and experience amps that may give rise to
problems in such areas unless they can precisely duplicate every detail of
a given wiring loom that is known to be OK.

Slainte,

Jim

--
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