[William Sommerwerck]

Again, I don't think that's true. The effect is probably multiplicative,
so
you have IM on top of IM. Nor am I certain that the amplifier's
non-linear
transfer characteristic can be modeled in such a simple way.

I'm certainly not an expert at this. I was thinking that the random noise
should power-add so you get 17dB more noise, but the odd order distortion
will add in phase so you get 34dB more distortion. You seem to be right
that this fails to take distortion of the distortion products into
account,
but surely this won't amount to very much extra at such low levels of
distortion.

Please don't call me surely.

The problem is... We don't know, because no one wants to do the listening
tests that would objectively establish what is and isn't audible.

[Peter Irwin]

Arny Krueger wrote:

Probably not bad recollections.

There are a number of reasons why a demo like the 50 Quad 303s would have
the results you mention. The first of which is the fact that the demo was
not a well-run ABX test with close, carefully chosen comparisons. Let me
choose the program material and any number of potentially audible sins will
not be heard. I know of audio gear that can come out clean over 20 passes,
but the same equipment would have audible effects over 50 passes.

To be fair to Peter Walker, he was personally convinced to the point
of certainty that good transistor amplifiers (such as, but not
limited to his own) were way way better performing than they needed
to be, and that good valve (tube) amplifiers were somewhat better
performing than they needed to be in order to have no sound of their
own.

He found that it was surprisingly difficult to persuade people of
what, to him, were evident truths. Hooking up fifty amplifiers in
series is a dramatic demonstration that could actually help convince
someone.

Peter.
--

[William Sommerwerck]

"Peter Irwin" wrote in message
...

To be fair to Peter Walker, he was personally convinced to the point
of certainty that good transistor amplifiers (such as, but not
limited to his own) were way way better performing than they needed
to be, and that good valve (tube) amplifiers were somewhat better
performing than they needed to be in order to have no sound of their
own.

He found that it was surprisingly difficult to persuade people of
what, to him, were evident truths. Hooking up fifty amplifiers in
series is a dramatic demonstration that could actually help convince
someone.

At least he performed the experiment, rather than just theorizing, or
depending on laboratory measurements.

The following remark is ironic. It is not meant to be sarcastic, or critical
of QUAD, or anyone posting here. ...

"If the 303 is such a good amp, why aren't we all using them?"

[Tobiah[_4_]]

On 11/17/2011 04:11 AM, Mike Rivers wrote:
On 11/16/2011 12:04 PM, Tobiah wrote:

What's an "input blade's input"?

I've made the mistake of using that 'term' here before. It's
obviously erroneous. Somewhere I got the idea that it referred
to one column of controls on the mixer. It's my alternative
to 'channel'

Well, if you're going to make up your own language, it's no wonder
nobody can understand what you're asking about.

I apologized as well as I could for the misuse of that word.

And you STILL haven't explained what you're trying to do in sufficient
detail that anyone can help you further.

Perhaps you missed some of the thread. I've been helped well, and
really have no more questions.

Thanks,

Tobiah

[Scott Dorsey]

William Sommerwerck wrote:

The following remark is ironic. It is not meant to be sarcastic, or critical
of QUAD, or anyone posting here. ...

"If the 303 is such a good amp, why aren't we all using them?"

We kind of all are. The 303 pretty much introduced the standard solid state
power amp topology that everyone uses today. It was a huge advance compared
with capacitively-coupled transistor circuits.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[PStamler]

On Nov 17, 10:06*am, "William Sommerwerck"
wrote:

"If the 303 is such a good amp, why aren't we all using them?"

Might have to do with their tendency to blow output transistors.

When I worked at a local PBS affiliate, we drove all the monitor
speakers (Altec and E-V) with Quad 303s. George, our chief engineer,
had to replace output transistors in one or another of the amps about
every three months.

Eventually we replaced them with BGW amps, the 50B I think. They
sounded cleaner (no, we didn't do a scientific listening test, we just
listened to our programming for hours on end), and they didn't blow
up. And they only occupied 1RU. There's probably a stack of QUADs in
the station's junk room to this day.

Peace,
Paul

[Neil Gould]

PStamler wrote:
On Nov 17, 10:06 am, "William Sommerwerck"
wrote:

"If the 303 is such a good amp, why aren't we all using them?"

Might have to do with their tendency to blow output transistors.

When I worked at a local PBS affiliate, we drove all the monitor
speakers (Altec and E-V) with Quad 303s. George, our chief engineer,
had to replace output transistors in one or another of the amps about
every three months.

Eventually we replaced them with BGW amps, the 50B I think. They
sounded cleaner (no, we didn't do a scientific listening test, we just
listened to our programming for hours on end), and they didn't blow
up. And they only occupied 1RU. There's probably a stack of QUADs in
the station's junk room to this day.

+1 on the BGW amps.

I was a BGW dealer in the '70s, and a 100B has been faithfully running my
personal stereo ever since. I think they went out of business because you
didn't need to buy more than one! ;-)

--
Neil

[Peter Larsen[_3_]]

Scott Dorsey wrote:

William Sommerwerck wrote:

The following remark is ironic. It is not meant to be sarcastic, or
critical of QUAD, or anyone posting here. ...

"If the 303 is such a good amp, why aren't we all using them?"

We kind of all are. The 303 pretty much introduced the standard
solid state power amp topology that everyone uses today. It was a
huge advance compared with capacitively-coupled transistor circuits.

Huh? - output has a coupling cap!

--scott

Kind regards

Peter Larsen

[Arny Krueger[_4_]]

"Peter Larsen" wrote in message
eb.com...
Scott Dorsey wrote:

William Sommerwerck wrote:

The following remark is ironic. It is not meant to be sarcastic, or
critical of QUAD, or anyone posting here. ...

"If the 303 is such a good amp, why aren't we all using them?"

We kind of all are. The 303 pretty much introduced the standard
solid state power amp topology that everyone uses today. It was a
huge advance compared with capacitively-coupled transistor circuits.

Huh? - output has a coupling cap!

Yes, and it isn't exactly generous - 2,000 uF per the schematic cited below.
This means that with certain loudspeakers, the output coupling capacitor
will cause a potentially audible increase in bass response. The cap is
outside of the feedback loop. There is also a series inductor that can lead
to a slight softening of response in the 20 KHz range.

Not only that, but the stock 303 uses a quasi-complementary rather than
full-complementary output stage. The output devices are classic slow,
NPN-only low-safe area devices (2N3055) as opposed to modern, fully
complementary, high safe-area devices such as those that one finds in just
about everything that is modern and halfways good, including most PA, MI,
and mid-fi home audio gear.

That all said, the 303 will probably pass and ABX comparison with a straight
wire with even the most critical of program material and loudspeakers, as
long as the operation of the speakers does not tax the 303's somewhat
limited abilities to handle low impedance and highly reactive loads, or
interact with the output choke or coupling capacitor to alter significantly
frequency response in the audible range.

You can find a schematic of the 303 at
http://www.richardbrice.net/quad33&303.htm .

[Scott Dorsey]

Peter Larsen wrote:
Scott Dorsey wrote:

William Sommerwerck wrote:

The following remark is ironic. It is not meant to be sarcastic, or
critical of QUAD, or anyone posting here. ...

"If the 303 is such a good amp, why aren't we all using them?"

We kind of all are. The 303 pretty much introduced the standard
solid state power amp topology that everyone uses today. It was a
huge advance compared with capacitively-coupled transistor circuits.

Huh? - output has a coupling cap!

Yes, and so does the input, but there aren't a million capacitors in-between.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[PStamler]

On Nov 18, 7:01*am, "Arny Krueger" wrote:
Huh? - output has a coupling cap!

Yes, and it isn't exactly generous - 2,000 uF per the schematic cited below.
This means that with certain loudspeakers, the output coupling capacitor
will cause a potentially audible increase in bass response.

Increase? Or rolloff?

Peace,
Paul

[Arny Krueger[_4_]]

"PStamler" wrote in message
...
On Nov 18, 7:01 am, "Arny Krueger" wrote:
Huh? - output has a coupling cap!

Yes, and it isn't exactly generous - 2,000 uF per the schematic cited
below.
This means that with certain loudspeakers, the output coupling capacitor
will cause a potentially audible increase in bass response.

Increase? Or rolloff?

Surprisingly, an increase.

One classic loudspeaker that had this *feature* was the AR-3. If you are
trying to squeeze a few more dB out of a subwoofer right above system
resonance, 2-3000 uF may do the job.

But, the susceptability of speaker systems to this problem varies. I first
noticed it with midrange drivers.