Re: The "Bordello Red" GSG build and questions
Posted: Tue Apr 29, 2014 11:14 am
I do think the couping capacitors in a design like the GSG would have a significant impact on the overall sound of the amp due to the simplicity of the design and the crappy effects of a capacitor on an audio signal; thus my focus on them. I've swapped rectifier tubes and heard basically no difference. I've also had two 6sl7gt's in here and aside from the obvious faults in the first tube and the difference in gain, heard very little, if any difference. When Matt finishes his GSG, we'll do a thorough comparison of the two amps, and try different output tubes, but I'm not expecting a whole lot of difference - we both have NOS tubes of different internal design - spearate plates vs connected plates. But anyway...
So then I swapped the coupling caps - and there's a BIG difference. And it's actually logical, if you think about it. The Mudorfs are not "normal" capacitors. They're two larger value caps in series in a single housing. The orange drops are more "normal" capacitors - just a single winding of 2 plates & 1 insulator. All the flowery, subjective terms used like, "sweet," "bright," "musical," "dark," etc, etc are quantifiable and can really be broken down to three groups (on my thinking):
1. Distortions (I include resonances in this group)
2. Frequency response (this includes harmonics, which are frequencies)
3. Dynamics - in this case, the limiting factors are impedance, resistances and inherent noise.
The Mundorfs likely have a little lower distortion than the Orange Drops (probably measurable by ESR), but the two caps in one housing roll off the upper mids, for whatever reason - be it impedance or whatever. I'd bet my house on that. That's what I was missing. I don't have nearly the experience rolling caps as I do other parts, but I do have some; my stash is modest - I've got some vitamin Q's, a bunch of ERO/West Germans, some GE's, Western Electrics (out of a phone switching machine), Mundorfs and a slew of unknowns. My observations tend towards generalizing capacitor "sound" by construction type and materials - paper insulated caps tend to be highly "colored" - meaning they exhibit distortions, non-linear curves re: frequency and other funkiness that comes from the variables inherent in paper, along with paper's propensity to greatly change dimensions (therefore capacitance and other quantifiable electrical measurements) depending on humidity and temperature. That's why I generally shy away from them and other organic materials like wax. I've never tried teflon caps. Paying $200 for a pair of coupling capacitors crosses my personal line of, "a fool and his money are soon parted." That, and I'm a cheap bastard. And I've learned that more expensive, especially in the hi-fi world, doesn't equal better. In fact, it rarely does. Interconnects are a prime example. I can build a set of interconnects for a few bucks that will sound better or as good as ANY interconnect on the planet (unless you're in an RFI-heavy environment. Then we've got to use shielded cables; when it gets really bad, go balanced.) The secret - not much of a secret, really - good insulation, good conduction and minimize electrical interaction between the two - capacitance and impedance.
Here's an example:
50 cent nickel plated brass connectors, bakelite connector housings (I've found fancy-pants metal housings typically introduce audible capacitance - even WBTs and the like; so I use them only in noisy environments), teflon insulated, stranded silver-plated copper conducts. Simple, cheap and will outperform thousand dollar "rhodium" interconnects. If you don't have that wire, try a twisted pair cribbed from an ethernet cable - almost as good.
Anywho - the differences between the Mundorfs and Orange Drops are huge, at least in my system. The one interesting great unknown is the psychological factor - here's what I mean by that. This morning, I fired up the Bordello, and it sounded a bit harsh and "glary" again this morning. It's now just afternoon, and I swear it's starting to mellow out. Now, is that the caps "re-breaking in," or is that just my perception? Is that a Seatlle Poncho or a real poncho? Who can tell anymore?
20to20 mentioned I might have some "meaningful insight" based on my profession - I dunno about "meanigful," but I can tell you this - we never "break in" ANYTHING. We might break it, but never break in. We just use it, and figure out how far from metered reference the "whatever it is" is - I look at vectorscopes and various flavors of waveforms and audio guys look at levels and phase meters. But mostly we just watch and listen what we're doing. That might explain why I NEVER watch TV at home. One of my composers hates what he calls, "Star Trek" equipment. One of his observations: if a vocalist brings a $5,000 mic onto his studio, he knows he's going to have a hard day, because the vocalist will suck.
Here's another interesting tidbit, work-related, and touches on the sound/brain interface. Do you know how Nielson and Arbitron (they just merged, btw), track over-the-air commercials? They insert an audio tone. SMACK DAB IN THE MIDDLE of the audio spectrum. This tone contains all relevant tracking information about that commercial. But have you ever heard anyone actually notice it or say something? Nope. But it's there, and loud/prominent enough to be recorded and played by by a VCR and heard by a mic in the room. As Spock (maintaining the Star Trek motif) would say.... "Hmmmm... fascinating."
Gregg - Thanks, and yeah, these speakers definitely have some of my serious time poured into them. There's another way to look at these speakers - just Fostex 103's with a tweeter and sub added. I actually codified that journey on AudioKarma:
http://www.audiokarma.org/forums/showth ... p?t=345806
Clearly, I was funnier then. I hope this is only a temporary lull in my humor. They started out as Cerwin Vegas - then I ultimately replaced virtually everything except for the boxes. Here's how the crossovers started:
The original crossover is on the right. At the top left is the Erse crossover I started with, and on the bottom left is how the Erse crossover went into the boxes *at first*.
And this is what they ended up like:
That's what they've looked like since I "finished" them. That picture actually makes me laugh. But it works. See - I do spend some time "tweaking" the sound,
It's probably good that I'm using those speakers as my reference point, because I just ordered a pair of Fostex Kanspeas with 103n's as desktop speakers to go with the Bordello.
And, because I've taken the photo, here's another "Bordello Red" beauty shot - notice how much taller the Sylvania 6sl7GT is compared to the GE tube (look back at an older photo):
So then I swapped the coupling caps - and there's a BIG difference. And it's actually logical, if you think about it. The Mudorfs are not "normal" capacitors. They're two larger value caps in series in a single housing. The orange drops are more "normal" capacitors - just a single winding of 2 plates & 1 insulator. All the flowery, subjective terms used like, "sweet," "bright," "musical," "dark," etc, etc are quantifiable and can really be broken down to three groups (on my thinking):
1. Distortions (I include resonances in this group)
2. Frequency response (this includes harmonics, which are frequencies)
3. Dynamics - in this case, the limiting factors are impedance, resistances and inherent noise.
The Mundorfs likely have a little lower distortion than the Orange Drops (probably measurable by ESR), but the two caps in one housing roll off the upper mids, for whatever reason - be it impedance or whatever. I'd bet my house on that. That's what I was missing. I don't have nearly the experience rolling caps as I do other parts, but I do have some; my stash is modest - I've got some vitamin Q's, a bunch of ERO/West Germans, some GE's, Western Electrics (out of a phone switching machine), Mundorfs and a slew of unknowns. My observations tend towards generalizing capacitor "sound" by construction type and materials - paper insulated caps tend to be highly "colored" - meaning they exhibit distortions, non-linear curves re: frequency and other funkiness that comes from the variables inherent in paper, along with paper's propensity to greatly change dimensions (therefore capacitance and other quantifiable electrical measurements) depending on humidity and temperature. That's why I generally shy away from them and other organic materials like wax. I've never tried teflon caps. Paying $200 for a pair of coupling capacitors crosses my personal line of, "a fool and his money are soon parted." That, and I'm a cheap bastard. And I've learned that more expensive, especially in the hi-fi world, doesn't equal better. In fact, it rarely does. Interconnects are a prime example. I can build a set of interconnects for a few bucks that will sound better or as good as ANY interconnect on the planet (unless you're in an RFI-heavy environment. Then we've got to use shielded cables; when it gets really bad, go balanced.) The secret - not much of a secret, really - good insulation, good conduction and minimize electrical interaction between the two - capacitance and impedance.
Here's an example:
50 cent nickel plated brass connectors, bakelite connector housings (I've found fancy-pants metal housings typically introduce audible capacitance - even WBTs and the like; so I use them only in noisy environments), teflon insulated, stranded silver-plated copper conducts. Simple, cheap and will outperform thousand dollar "rhodium" interconnects. If you don't have that wire, try a twisted pair cribbed from an ethernet cable - almost as good.
Anywho - the differences between the Mundorfs and Orange Drops are huge, at least in my system. The one interesting great unknown is the psychological factor - here's what I mean by that. This morning, I fired up the Bordello, and it sounded a bit harsh and "glary" again this morning. It's now just afternoon, and I swear it's starting to mellow out. Now, is that the caps "re-breaking in," or is that just my perception? Is that a Seatlle Poncho or a real poncho? Who can tell anymore?
20to20 mentioned I might have some "meaningful insight" based on my profession - I dunno about "meanigful," but I can tell you this - we never "break in" ANYTHING. We might break it, but never break in. We just use it, and figure out how far from metered reference the "whatever it is" is - I look at vectorscopes and various flavors of waveforms and audio guys look at levels and phase meters. But mostly we just watch and listen what we're doing. That might explain why I NEVER watch TV at home. One of my composers hates what he calls, "Star Trek" equipment. One of his observations: if a vocalist brings a $5,000 mic onto his studio, he knows he's going to have a hard day, because the vocalist will suck.
Here's another interesting tidbit, work-related, and touches on the sound/brain interface. Do you know how Nielson and Arbitron (they just merged, btw), track over-the-air commercials? They insert an audio tone. SMACK DAB IN THE MIDDLE of the audio spectrum. This tone contains all relevant tracking information about that commercial. But have you ever heard anyone actually notice it or say something? Nope. But it's there, and loud/prominent enough to be recorded and played by by a VCR and heard by a mic in the room. As Spock (maintaining the Star Trek motif) would say.... "Hmmmm... fascinating."
Gregg - Thanks, and yeah, these speakers definitely have some of my serious time poured into them. There's another way to look at these speakers - just Fostex 103's with a tweeter and sub added. I actually codified that journey on AudioKarma:
http://www.audiokarma.org/forums/showth ... p?t=345806
Clearly, I was funnier then. I hope this is only a temporary lull in my humor. They started out as Cerwin Vegas - then I ultimately replaced virtually everything except for the boxes. Here's how the crossovers started:
The original crossover is on the right. At the top left is the Erse crossover I started with, and on the bottom left is how the Erse crossover went into the boxes *at first*.
And this is what they ended up like:
That's what they've looked like since I "finished" them. That picture actually makes me laugh. But it works. See - I do spend some time "tweaking" the sound,
It's probably good that I'm using those speakers as my reference point, because I just ordered a pair of Fostex Kanspeas with 103n's as desktop speakers to go with the Bordello.
And, because I've taken the photo, here's another "Bordello Red" beauty shot - notice how much taller the Sylvania 6sl7GT is compared to the GE tube (look back at an older photo):