Bypassing caps? How about with wire?

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On Tue, 27 Jul 2004 17:52:34 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>Specifically, which Yamaha amp(s) are you talking about?

The M series Yamaha's of that era have several known defects,
including hot glue which has by now baked to a corrosive and
partially conductive state, and solder joints old enough to
vote and frequently marginal now.

And, of course, the inevitable electrolytics well past their
prime. But even when you restore all the things that you know
about, they're still not great.

Design choices that emphasize .00x THD figures sacrifice some
other virtues which actually matter more. Stability under
dynamic and especially ultrasonic stress, small signal
linearity, spectral content of residual distortion products,
insensitivity to ground and power supply contamination,
recovery from transient overloads, etc.

These and similar issues don't fit easily into a "spec sheet"
but are critical in real electronics.

As you know. I've seen your name in old construction articles
from 20 plus years ago; you've gotten your hands dirty too.

Chris Hornbeck
"Vote or Die" - P. Diddy

 

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On Tue, 27 Jul 2004 21:59:02 -0600, "Stephen Sank" <bk11@thuntek.net>
wrote:

>I imagine you are also familiar with the succeding MX-xxx series that replaced the M85/65/45.
>Sounded even worse, and loved to blow up as ballistically as Phase Linear 400's.

Well, I've been off the front lines for a while now. And I wouldn't
really want to pan Yamaha specifically; my gripes are kinda generic.

Besides, I *love* their little $100 mixer. Maybe not a Mackie, but
not bad at all. It even feels good.

And the 1980's were a difficult time anywho. We were all just trying
to find our way. Or something.

Anyway, thanks for your comments,

Chris Hornbeck
"Vote or Die" - P. Diddy

 

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Phil Allison <philallison@tpg.com.au> wrote:
>
>
> BTW He still will * not * name the TV repair business in Sydney that he
>alleged I run.

I will again. http/www.allisonaudio.com.au.

Perhaps your shouting about lack of evidence has to do with the fact that
people present you with urls and citations that you ignore?
--scott

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

 

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"Scott Dorsey"

>
> Either one of these amplifiers will horribly fail a TIMD test. As will
> the Phase Linears and Dynaco ST120s.
>

** TIMD ( and SID) have been well and truly been proved to be a myths as
far as the reproduction of music program is concerned.

Matti Otala was wrong as well - his published maths contained a basic
error.



> The reason we _have_ TIMD testing is because of all the amps in the
seventies
> that sounded bad but measured well.


** That is another wild and wrong assertion.


> So somebody had to come up with a test
> that explained why they sounded bad.


** No formal listening tests ever showed that 70s amps "sounded bad".

Quite the opposite was found in fact when controlled tests were done.



>
> Now we're living in a world of perceptual encoding systems which measure
> well and sound bad,


** Wrong again.




............. Phil

 

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Phil Allison <philallison@tpg.com.au> wrote:
>"Scott Dorsey"
>>
>> Either one of these amplifiers will horribly fail a TIMD test. As will
>> the Phase Linears and Dynaco ST120s.
>>
>
>** TIMD ( and SID) have been well and truly been proved to be a myths as
>far as the reproduction of music program is concerned.
>
> Matti Otala was wrong as well - his published maths contained a basic
>error.

Have you got any citations for these statements?

And, can you give me any better explanation for the ST120 sounding so bad,
for instance?

>** No formal listening tests ever showed that 70s amps "sounded bad".
>
> Quite the opposite was found in fact when controlled tests were done.

How can you expect to have any credibility when you make statements like
this? These amps were so noxious that a deaf elephant could tell how
harsh they sounded.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

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"Phil Allison" <philallison@tpg.com.au> wrote in message
news:2mpqujFp339cU1@uni-berlin.de
> "Scott Dorsey"

>> Either one of these amplifiers will horribly fail a TIMD test. As
>> will the Phase Linears and Dynaco ST120s.

AFAK, there's no AES or other comparable organization standard TIM test. I'm
willing to go this this suggestion:

http/www.benchmarkmedia.com/appnotes-a/caig/caig08-10.asp

"If slewing induced intermodulation and/or transient intermodulation
distortion exist within the system, it will only occur at the higher
frequencies. The best way in a bandwidth limited system to detect their
presence is with the CCIF twin tone IM distortion measurement. By using 14
and 15 kHz tones mixed 1:1, a 1 kHz IM product is easily detected if SID/TIM
exists in an FM broadcast system. A 19 and 20 kHz pair may be used to
evaluate A-to-D converters or other equipment in the audio chain. We believe
that every broadcast facility should perform twin tone IM distortion
measurements to see the truth about heir high frequency audio performance. "

I've recently done twin-tone tests on a number of ca. 70s power amps
including the Dyna ST120, and it doesn't seem to measure out as having this
problem. Admittedly, I might have one of the few ST120's that appears to be
operating with its original output devices, not that spares aren't on hand!


> ** TIMD ( and SID) have been well and truly been proved to be a
> myths as far as the reproduction of music program is concerned.

> Matti Otala was wrong as well - his published maths contained a basic
error.

He published corrections, later on.

Otala's 1977 article seems to agree the Benchmark Media paper mentioned
above:

"The CCIF-IM method gives a reliable indication of dynamic intermodulation
distortion."

>> The reason we _have_ TIMD testing is because of all the amps in the
>> seventies that sounded bad but measured well.

> ** That is another wild and wrong assertion.

It's also self-contradictory.

Marshall Leach first published the Audio Magazine construction articles for
his "Low TIM" amplifier in February 1976. Therefore, it would seem to be
safe to say that there were a goodly number of low-TIMD solid state
amplifiers in the 1970s since the technology for building them was
well-known just after the middle of the decade.

http/users.ece.gatech.edu/~mleach/papers/lowtim/feb76feb77articles.pdf

>> So somebody had to come up with a test
>> that explained why they sounded bad.

> ** No formal listening tests ever showed that 70s amps "sounded bad".

As a general rule, no these amps didn't all sound bad.

> Quite the opposite was found in fact when controlled tests were
> done.

Agreed.

>> Now we're living in a world of perceptual encoding systems which
>> measure well and sound bad,

> ** Wrong again.

It is true that at least some of the best-known bad sounding perceptual
coders also measured bad. Please see:

http/www.pcavtech.com/techtalk/compare_perceptual/index.htm

 

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Phil Allison <philallison@tpg.com.au> wrote:
>Kludge wrote:
>
> The slew rates contained in program material can be easily shown to never
>approach the rates needed to induce TIMD or SID in commercial SS hi-fi amps.

I'm not sure I buy that, but I'm looking up the issues to see.

>> And, can you give me any better explanation for the ST120 sounding so bad,
>> for instance?
>
>
>** That is called "begging the question" - a favourite cheat used by
>liars.

No. You might have plenty of other good explanations, like high order
distortion products. Or the fact that the amplifier is on the bare edge
of instability and breaks out into ultrasonic oscillation on some source
material peaks.

>> >** No formal listening tests ever showed that 70s amps "sounded bad".
>> >
>> > Quite the opposite was found in fact when controlled tests were done.
>>
>>
>> How can you expect to have any credibility when you make statements like
>> this?
>
>
>** Then kindly supply evidence from formally conducted listening tests that
>backs you up.

Suppression of Slew Rate and Transient IM Distortions in Audio Power Amplifiers
Marshall W. Leach, AES preprint 1137

(This is pretty much the grandaddy of all of these things and predates the
Audio magazine articles that Leach did. And yes, there IS a listening test and
it does correlate.)

Slewing Induced Distortion and Its Effect On Audio Amplifier Performance--
With Correlated Measurement/Listening Results
Jung, Walter G.; Stephens, Mark L.; Todd, Craig C., AES preprint 1252

Envelope Distortion in Audio Amplifiers
Takahashi, Susumu; Funada, Saburo, AES preprint 1344

Interface Intermodulation Distortion (IIM) in Power Amplifiers
Corveleyn, L.; Bossuyt, F.; Sansen, W., AES preprint 1869

(This paper is rather different than the others since it is specifically
relating to intermodulation effects induced by the load nonlinearity).

Transient Distortion in Feedback Audio Power Amplifiers
Glowacki, Miecyslaw; Stanclik, Josef; Pierzchala, Marian, AES preprint 3605

(The listening tests in this one are fairly minimal, but the model being
used is a fairly important one that gets cited a lot in other testing.)

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

 

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"Scott Dorsey" <kludge@panix.com> wrote in message
news:ce8e48$k89$1@panix2.panix.com...
> And, can you give me any better explanation for the ST120 sounding
so bad,
> for instance?
>
> >** No formal listening tests ever showed that 70s amps "sounded
bad".
> >
> > Quite the opposite was found in fact when controlled tests
were done.
>
> How can you expect to have any credibility when you make statements
like
> this? These amps were so noxious that a deaf elephant could tell
how
> harsh they sounded.

I don't know about deaf elephants, but apparently the designer of the
ST120 didn't think his amp sounded bad--or he wouldn't have put it on
the market. Additionally, since the ST120 sold briskly, I would have
to assume that its faults were not immediately evident to customers.

BTW, was the ST120 a Hafler design?

Norm Strong

 

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normanstrong <normanstrong@comcast.net> wrote:
>
>I don't know about deaf elephants, but apparently the designer of the
>ST120 didn't think his amp sounded bad--or he wouldn't have put it on
>the market. Additionally, since the ST120 sold briskly, I would have
>to assume that its faults were not immediately evident to customers.
>
>BTW, was the ST120 a Hafler design?

I don't know if it was a Hafler design or not. It has some interesting
little tricks to it, like the huge inductor wound around a capacitor can
that is used on the output in an attempt to keep the thing stable and some
biasing goofiness to avoid using a bipolar supply with a push-pull output
stage.

I do know that David Hafler does use it as an example of one of the bad
early power amp designs.

The thing is that the ST120, when compared with the tube amps of the
era, sounded very bright and forward (probably because of all the high
order harmonics). This seemed like a good thing to a lot of people back
then, but it's the sort of thing that eventually gave solid state
electronics a bad name. It took some listening, though, for people to
realize what was going on, because they were being presented with a set
of distortions that they weren't used to listening to.

This is always the case. When the Edison phonograph came out, many people
said that it was just like listening to the performer right there in the
room, it was so accurate. It took people a few years to get used to the
sound and understand the deficiencies.

The same thing happens every time there is a revolutionary change in
design. It happened with solid state electronics and it happened with
digital audio and it's happening right now with perceptual encoding systems.
It takes people a while to recognize what they are listening to.
--scott


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

 

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It was either Joe Norris or David Hafler, or both together, that designed the Dynaco ST120. It
is clearly one of the worst sounding power amps of all time. Besides the instability, it was
also Class B bias, so it had enormous amounts of crossover distortion in the very important low
power range. And I think the reason they sold so well was not as much because of the novelty
of their, cough, "sound", as much as it was due to how extremely cheap they were, especially in
kit form(at a time when kits were very, very popular).
Indeed, anyone who does not acknowledge that the ST120 sounds really bad(at least on any
speaker with response above 5kHz) has absolutely NO credibility for giving any opinions about
audio gear.

--
Stephen Sank, Owner & Ribbon Mic Restorer
Talking Dog Transducer Company
http/stephensank.com
5517 Carmelita Drive N.E.
Albuquerque, New Mexico [87111]
505-332-0336
Auth. Nakamichi & McIntosh servicer
Payments preferred through Paypal.com
"Scott Dorsey" <kludge@panix.com> wrote in message news:ce8os5$6ih$1@panix2.panix.com...
> normanstrong <normanstrong@comcast.net> wrote:
> >
> >I don't know about deaf elephants, but apparently the designer of the
> >ST120 didn't think his amp sounded bad--or he wouldn't have put it on
> >the market. Additionally, since the ST120 sold briskly, I would have
> >to assume that its faults were not immediately evident to customers.
> >
> >BTW, was the ST120 a Hafler design?
>
> I don't know if it was a Hafler design or not. It has some interesting
> little tricks to it, like the huge inductor wound around a capacitor can
> that is used on the output in an attempt to keep the thing stable and some
> biasing goofiness to avoid using a bipolar supply with a push-pull output
> stage.
>
> I do know that David Hafler does use it as an example of one of the bad
> early power amp designs.
>
> The thing is that the ST120, when compared with the tube amps of the
> era, sounded very bright and forward (probably because of all the high
> order harmonics). This seemed like a good thing to a lot of people back
> then, but it's the sort of thing that eventually gave solid state
> electronics a bad name. It took some listening, though, for people to
> realize what was going on, because they were being presented with a set
> of distortions that they weren't used to listening to.
>
> This is always the case. When the Edison phonograph came out, many people
> said that it was just like listening to the performer right there in the
> room, it was so accurate. It took people a few years to get used to the
> sound and understand the deficiencies.
>
> The same thing happens every time there is a revolutionary change in
> design. It happened with solid state electronics and it happened with
> digital audio and it's happening right now with perceptual encoding systems.
> It takes people a while to recognize what they are listening to.
> --scott
>
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

 

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On 28 Jul 2004 13:47:49 -0400, kludge@panix.com (Scott Dorsey) wrote:

>The same thing happens every time there is a revolutionary change in
>design. It happened with solid state electronics and it happened with
>digital audio and it's happening right now with perceptual encoding systems.
>It takes people a while to recognize what they are listening to.

When people in pre-technological societies are first shown photographs
they frequently can't distinguish between the portrait and the person.

The difficult 99% of perception is in the wetware. But our
unchallenged faith in "objectivity" is touching.

Chris Hornbeck
"Vote or Die" - P. Diddy

 

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"Scott Dorsey" <kludge@panix.com> wrote in message
news:ce8os5$6ih$1@panix2.panix.com

> normanstrong <normanstrong@comcast.net> wrote:

>> I don't know about deaf elephants, but apparently the designer of the
>> ST120 didn't think his amp sounded bad--or he wouldn't have put it on
>> the market. Additionally, since the ST120 sold briskly, I would have
>> to assume that its faults were not immediately evident to customers.

>> BTW, was the ST120 a Hafler design?

According to http/home.indy.net/~gregdunn/dynaco/components/ST120/

It was designed by Ed Laurent (power supply by Sid Lidz).

> I don't know if it was a Hafler design or not. It has some
> interesting little tricks to it, like the huge inductor wound around
> a capacitor can that is used on the output in an attempt to keep the
> thing stable and some biasing goofiness to avoid using a bipolar
> supply with a push-pull output stage.

The inductor trick basically didn't work, and thereby added to the amp's
lack of reliability.

The hookup wire coil is wound around the large aluminum bodies of the output
coupling caps. The body of the cap acts like a shorted turn and vastly
decreases the inductance of the inductor. This inductor is added to most SS
amps to improve stability and durability by countering the ability of
capacitive loads to load down the output of the amplifier. Measurements I've
done on my ST120 show a relatively low increase in source impedance at high
frequencies compared to other amps.

According to the source cited above:

"In use with varying program material, the Stereo 120 achieves its design
goals of sonic ease and naturalness always sought but rarely achieved in
solid state designs. There is remarkable clarity and an impression of direct
contact with the original without the extra brightness or stridency which,
unfortunately, is sometimes attributed to high fidelity sound, but rather
there is an impression of limitless range and effortless handling of the
highest power peaks."

It is no doubt, one of the most hated and reviled of all solid state
amplifiers, which is the reason I collected mine via eBay purchase.

BTW, another widely-reviled solid state power amplifier is the Alesis RA-100
and I have one of those as well.

But no, I don't have a Phase Linear 700 or 400. ;-)

 

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Arny Krueger wrote:

<snip>

>It is no doubt, one of the most hated and reviled of all solid state
>amplifiers, which is the reason I collected mine via eBay purchase.
>
>BTW, another widely-reviled solid state power amplifier is the Alesis RA-100
>and I have one of those as well.

That's interesting, Arny, and make me curious. Are you into collecting
amplifiers of ill repute?

>But no, I don't have a Phase Linear 700 or 400. ;-)

No? Then you must have some other motivation. Do tell, please.

--
========================================================================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mkesti@gv.net | - The Who, Bargain

 

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In article <41083CC2.66326DA1@gv.net>, Michael R. Kesti <mkesti@gv.net> wrote:
>Arny Krueger wrote:
>>It is no doubt, one of the most hated and reviled of all solid state
>>amplifiers, which is the reason I collected mine via eBay purchase.
>>
>>BTW, another widely-reviled solid state power amplifier is the Alesis RA-100
>>and I have one of those as well.
>
>That's interesting, Arny, and make me curious. Are you into collecting
>amplifiers of ill repute?

I tossed my ST120 and the Crown D-60, but I can probably find an ST410
around here. It's bad although not in the same league as the ST120.
You need it, Arny?

>>But no, I don't have a Phase Linear 700 or 400. ;-)
>
>No? Then you must have some other motivation. Do tell, please.

I remember setting up a film rig in some hall and asking the house tech
when the last time the fire curtain was used, and he said that they haven't
dropped it at all since the touring crews stopped using Phase Linears.
--scott

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

 

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"Michael R. Kesti" <mkesti@gv.net> wrote in message
news:41083CC2.66326DA1@gv.net
> Arny Krueger wrote:
>
> <snip>
>
>> It is no doubt, one of the most hated and reviled of all solid state
>> amplifiers, which is the reason I collected mine via eBay purchase.

>> BTW, another widely-reviled solid state power amplifier is the
>> Alesis RA-100 and I have one of those as well.

> That's interesting, Arny, and make me curious. Are you into
> collecting amplifiers of ill repute?

Yes.

Just like my subcollection of totally vile sound cards. BTW, these really do
sound different!

>> But no, I don't have a Phase Linear 700 or 400. ;-)

> No? Then you must have some other motivation. Do tell, please.

Just haven't found one of each for the right price.

 

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"Scott Dorsey" <kludge@panix.com> wrote in message
news:ce9fsr$aan$1@panix2.panix.com
> In article <41083CC2.66326DA1@gv.net>, Michael R. Kesti
> <mkesti@gv.net> wrote:
>> Arny Krueger wrote:
>>> It is no doubt, one of the most hated and reviled of all solid state
>>> amplifiers, which is the reason I collected mine via eBay purchase.
>>>
>>> BTW, another widely-reviled solid state power amplifier is the
>>> Alesis RA-100 and I have one of those as well.
>>
>> That's interesting, Arny, and make me curious. Are you into
>> collecting amplifiers of ill repute?
>
> I tossed my ST120 and the Crown D-60, but I can probably find an ST410
> around here. It's bad although not in the same league as the ST120.
> You need it, Arny?

Thanks but no thanks. I have two ST400s and that seems like enough. My
remaining boat-anchor storage area is being saved for some Phase Linears.
BTW, ST400s actually do sound bad with a suitably reactive load. One of my
400s has double-the-SOA output devices, and recalibrated protection circuits
to match. Helps.

>>> But no, I don't have a Phase Linear 700 or 400. ;-)

>> No? Then you must have some other motivation. Do tell, please.

> I remember setting up a film rig in some hall and asking the house
> tech when the last time the fire curtain was used, and he said that
> they haven't dropped it at all since the touring crews stopped using
> Phase Linears.

Hence the rep: "Flame Linear". I'm under the impression that eventually
Carver found output devices that were as big as his SOA protectors.

 

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"Scott Dorsey"
> Phil Allison :
> >
> >
> > BTW He still will * not * name the TV repair business in Sydney that
he
> >alleged I run.
>
> I will again. http/www.allisonaudio.com.au


** That is the first time I have seen that URL posted here - plus I can
find no sign of it on Google Groups.

The owner of that business is ** Dave ** Allison - and he is not any
relative of mine.

Why don't you ring Dave and find out ?




............ Phil

 

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In article <2mprsgFpc1t2U1@uni-berlin.de>,
Phil Allison <philallison@tpg.com.au> wrote:
>
>"Scott Dorsey"
>> Phil Allison :
>> >
>> >
>> > BTW He still will * not * name the TV repair business in Sydney that
>he
>> >alleged I run.
>>
>> I will again. http/www.allisonaudio.com.au
>
>** That is the first time I have seen that URL posted here - plus I can
>find no sign of it on Google Groups.

I posted it in reply to your previous comment goading me about it.

> The owner of that business is ** Dave ** Allison - and he is not any
>relative of mine.
>
> Why don't you ring Dave and find out ?

If I ever need any work done in Sydney again, I probably will ring him.
He did nice work on the FP32.
--scott

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

 

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"Scott Dorsey"
> Phil Allison

> >> >
> >> > BTW He still will * not * name the TV repair business in Sydney
that
> > he alleged I run.
> >>
> >> I will again. http/www.allisonaudio.com.au
> >
> >** That is the first time I have seen that URL posted here - plus I
can
> >find no sign of it on Google Groups.
>
> I posted it in reply to your previous comment goading me about it.
>

** So you have to be goaded into telling the simple truth - while
monstrous lies come gushing out in torrents.



> > The owner of that business is ** Dave ** Allison - and he is not any
> >relative of mine.
> >
> > Why don't you ring Dave and find out ?
>
>
> If I ever need any work done in Sydney again, I probably will ring him.


** You need to contact him to find out his name - seeing as you told
everyone here it was Phil.

Quote: " It turns out I have a customer who actually had him do some
work. Phil owns a neighborhood TV repair shop in Sydney, if it's the same
Phil. "


** Just another one of Scott Dorsey's lies - far too many to count.





........... Phil

 

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On Wed, 28 Jul 2004 21:18:02 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>> That's interesting, Arny, and make me curious. Are you into
>> collecting amplifiers of ill repute?


>>> But no, I don't have a Phase Linear 700 or 400. ;-)
>
>> No? Then you must have some other motivation. Do tell, please.
>
>Just haven't found one of each for the right price.

I actually do know a guy who's been collecting and restoring
Phase Linear 400's for years. I'd like to say that otherwise
he's perfectly normal, but, well, ..

Chris Hornbeck
"That's the way Stravinsky was. Bup, Bup, Bup, Bup.
The poor guy's dead now. Play it legato." -Eugene Ormandy