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Old 24th September 2003, 08:15 PM   #91
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Location: LA
Hi Magnus,
I work in WLA, live in Brentwood, so we must be neighbors.

I am currently building a gainclone with "boutique" parts. Using Jensen 4 pole electrolytic and Blackgate caps. Resistors will either be Caddocks, Riken, Tantalums or Resista's depending on what I end up picking.

Maybe we could get together some time and compare projects? I know a few other audio guys in the area, but nobody else into DIY stuff.

BTW, rest of my system is a EVS modded SA-14, Stan Warren modded Adcom 5200, DIY transformer volume control using SB tx102's, and Tyler Acoustics Taylo Reference monitors. All cables and PC's are DIY.

Randy
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Old 24th September 2003, 08:35 PM   #92
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Hi,

I bet we are neighbors when we live on Montana and 20th, and soon less neighbors moving down to Euclid and Montana.



Sure we could, would be fun to compair your boutique GC to one of my cheapo parrallel almost for free GC and see how much better yours are and if it would be worth the bucks to start using boutique parts.

/Magnus
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Old 24th September 2003, 10:00 PM   #93
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Quote:
Originally posted by NoKnowledge
Hi,

I bet we are neighbors when we live on Montana and 20th, and soon less neighbors moving down to Euclid and Montana.



Sure we could, would be fun to compair your boutique GC to one of my cheapo parrallel almost for free GC and see how much better yours are and if it would be worth the bucks to start using boutique parts.

/Magnus
I live on Pesquera, which is in the hills north of Sunset, off of Westridge, off of Mandeville canyon. 20th is close, Euclid as, but not far either.

I hope to finish my gainclone in the next couple of weeks, but then it will need a few weeks to break in. I'll let you know when it's ready.

Randy
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Old 24th September 2003, 10:21 PM   #94
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OK let me know when it is ready, my cheapo stuff doesn't need to break in, most of my components are prebreaked in on Salvation army

Adjö Senapsfrö

/Magnus
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Old 24th September 2003, 10:34 PM   #95
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Hi,

Quote:
Adjö Senapsfrö
Swedish?

The first word, adjö, sounds like the french adieu.

The other one will require some first grade parts to figure out....assuming I got the first one right...

Cheers,
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Old 24th September 2003, 10:50 PM   #96
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Yes Swedish!

Your guess is right!

senapsfrö = mustard seed, so I guess have thoose first grade parts here!

/Magnus
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Old 24th September 2003, 11:07 PM   #97
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Quote:
Originally posted by IanHarvey
Parasitic inductance or capacitance is linear, and does not therefore produce distortion; it will only cause such things as wobbles in the frequency response. (I justified this in more detail on the recent loudspeaker cables thread).
I agree on this. It is interesting to note though, that the usual
models for dielectric absorption (DA) in capacitors are linear,
yet a lot of people insist DA causes distorsion. It has never
become clear to me if they use the term distorsion more liberally
or if they do not accept the DA models used even by Marsh&Jung.

Quote:

Thanks, Jonathan, for the info on the preamp - real measurements and hard facts are so much more persuasive. For instance, we might conjecture that carbon resistors change slightly in value depending on applied voltage; if this is the case it's not too hard to build a test circuit to measure it. One could then publish results for every resistor under the sun without any accusations of subjectivity creeping it.
All resistors are voltage dependent. Quoting some figures from
the fact pages in the Elfa catalogue we have:
carbon comp. 200 - 500 ppm/V
carbon film <100 ppm/V
metal film c:a 1 ppm/V
metal oxide < 10 ppm/V
wire wound c:a 1 ppm/V

They also say (not surprisingly) that this dependency
causes distorsion and that it is often stated as a ratio in dB
between the signal and the third overtone. I have yet to see
such a figure in a datasheet though. (Elfa don't even have
datasheets for the resistors they sell. ).
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Old 25th September 2003, 12:01 AM   #98
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Hi,

Not that I mind, but after about 14 months of forum activity it dawns on me that this is a cyclic event...

No one ever learned anything and those who actually did do the hands on job keep quiet about it.

In the meantime the oldtimers, just have to rehash the old stuff.

Was it Fred Dieckmann who first used the Deja Vu description?

Yes, Marsh and Jung did a good analysis on caps but how many have actually read the papers?

Not many from what I read.

And no, there's no way you can do without coupling caps just as you can't do without a PS so, why not go for the best?

Cheers,
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Old 25th September 2003, 01:28 AM   #99
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Quote:
Originally posted by fdegrove
And no, there's no way you can do without coupling caps just as you can't do without a PS so, why not go for the best?

Cheers,

"where he built
the celebrated
mechanical cow
in which the queen
hid herself
in order to seduce the bull
her perverse passion
and from that
unnatural union
was born
the minotaur
a man
with the head and neck
of a bull "

Yeah? I don't think so.

Enjoy.
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Old 25th September 2003, 06:49 AM   #100
jcarr is offline jcarr  United States
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Christer:

>They also say that this dependency causes distorsion and that it is often stated as a ratio in dB between the signal and the third overtone.<

This sounds right. I am fairly sure that the prime distortion component that I was looking at from the carbon resistors was third-order.

Jan:

>What about the higher noise figure of the carbons vs the metal foils? Would it be possible that at the low levels, they were similar because the noise was the dominant factor? Then you raise the level, improve the S/N ratio of the circuit, but since the carbon noise is larger it doesn't climb that far out of the noise as the metals do?<

Seems plausible that this could contribute something, but I wouldn't know how large the magnitude would be.

It wasn't as though the carbons and metal-films showed different distortion curves altogether. Out to about 9Vrms, the respective distortion figures dropped at reasonably similar rates. But at higher output voltages, the results looked like they came from different circuits. I would be willing to entertain the possibility that the 0.00035% at 9Vrms reading implied some kind of noise threshold.

The particular circuit that I was using was quite handy for this kind of testing where you want to study voltage dependencies (it had a leading and trailing slew rate of 340V/us, and could swing full power out to past 1MHz). But I've since disassembled it (there were things about it that I didn't like), and the line-level circuits that I have now aren't designed to swing that kind of voltage.

But I will certainly intend to make a circuit with similar or greater output voltage capability in the future, and at that time, I may choose to look at resistors again.

Jan, MM sounds really interesting. But right now my hands are full with a complex board layout project. Would it be OK if I emailed you back in a week or so? I'd appreciate the extra time.

best regards, jonathan carr
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