Teflon Coupling Caps In Vintage Tube Amps . . .

[FalconEddy]

I searched; but, got strange and conflicting information about this.

So, has anyone actually replaced the original coupling caps (or whatever someone rebuilt the amp with), and used a boutique-type teflon dielectric and foil capacitor. RUSSIAN MILITARY K72's and FT SERIES ARE NOT ON THE TABLE FOR DISCUSSION HERE. I'm specifically talking about Audience AuraT Teflon, V-Cap TFTF, Sonicap Platinum, RelCap TFT, Solen FEP/SN Supersound, American Capacitor Corp, Sonicap Platinum, Obbligato Supersound (which is the same cap as the Solen with a different mfg name on it), Psvane.

I'm curious as to what you thought happened to the 'vintage' sound after the change out from the original coupling caps, or if someone had mylar (polyester) in there. Did it brighten up the sound too much, or just enough and also left the midrange bloom inherent to most vintage designs?

If the changeout was from a polypropylene film and foil, or metallized polypropylene; who's brand was in there, and did it brighten up the output even more, or tame any harshness and just bring more details out of the music?

Also wondering if anyone has used the AudioCap RT single wind polystyrene film and foil for coupling caps? I noticed it got a lot of attention with vintage amp restoration guys over the past few years, and was put up on the top shelf with the teflon and foil caps in a few tests. The only downside was the max temp rating of 85°C, and that's not an issue for me since my component temps (with moving air) average between 29°C to 41°C.

. . Falcon

 

[PakProtector]

Why exclude the Russian stuff?
cheers,
Douglas

 

[audiodon]

Auricaps don't count? Guess not. Incorrect formulation.

I've been heading in the premium Paper in Oil (PIO) direction, graduating from Jensens to Mundorfs, with Duelunds in sight next, but this thread's results may sway me for my next premium project.

 

[golana]

With your specifications, I think you have narrowed possible thread participants to, one or two.

 

[derekva]

I've used various inexpensive mylar coupling caps in Maggie amps and haven't noticed too much of a deviation from the stock 'vintage' sound. I don't use the expensive boutique caps as (1) I can't afford them and (2) I can't really tell the difference...or enough difference to justify the cost. I think you'll get more deviation if you stiffen up the power supply and use closely matched tubes (or, for that matter, replace old, out-of-spec passive components with new components, regardless of make).

-D

 

[FalconEddy]

Auricaps don't count? Guess not. Incorrect formulation.

I've been heading in the premium Paper in Oil (PIO) direction, graduating from Jensens to Mundorfs, with Duelunds in sight next, but this thread's results may sway me for my next premium project.

Nope, only their big brothers . . . the AuraT's

As a side note, if my hypothesis is correct, the teflon caps will be even MORE detailed than the Auricaps. No harshness, no glare.

The polystyrene and foil should be nearly the same at about 1/10th the cost.

I used polystyrene and foil caps to rebuild and tweak some inexpensive matched Russian made Oktava MK-219 mics I purchased a few years ago, and now the frequency response is nearly a carbon copy for my Neumann U87 when in the hypercardioid pattern.

Why exclude the Russian stuff?
cheers,
Douglas

Because neither the K72 or the FT series are consistent enough for me, sound wise. Sure, I could purchase a bunch and weed and match, but I don't want to have to do that. Then, will I have to deal with other matching issues after break-in?

Being an Audio Mastering Engineer has its drawbacks simply due to ultra critical listening habits.

With your specifications, I think you have narrowed possible thread participants to, one or two.

Yes, I know. It was my intention. After all, how many people are going to put $325 to $500 worth of boutique teflon coupling caps into a vintage amp?

However, perhaps someone took the chance on the AudioCap RT single wind or the AudioCap RTX 10 segment caps for their coupling cap choice. These are generally overlooked, but I think I'm about to change all that.

Bear in mind this is all coming from a staunch supporter of a restoring a vintage amp to (as close as the designer intended) the original sound.

. . Falcon

 

[gearhound]

Many older amps used Polyester or even Ceramic capacitors as coupling caps.
Since Polyester caps are dirt cheap, it's an easy call to try to keep the 'original' sound.

Steve

 

[kvflyer]

As you guys must have read sometime in the past, I am NOT a fan of paying ridiculous money for boutique capacitors. I started using Orange Drops (not Orange Dips, whatever they are?). Since they are a little big, I was "converted" to the little yellow "Lemon Drops". They are just fine, price is right, very reliable and fit every location that the old ones were in. And sound the same. Ceramic capacitors are usually still good. But I will usually replace them with axial capacitors.

The little yellow jobs are good for re-stuffing vintage paper capacitors too. I have done a few but have not had equipment on the bench that warrant that much restoration effort. Aluminum FP style electrolytic capacitors are another story. I always open them up at the crimp, clean them out, stuff in new smaller caps and close the crimp with a new steel common terminal ring. I can do one in about an hour, the same time it takes to try to cobble something under the chassis. And, if you have worked on an HH Scott product, especially the 340B etc., there ain't much room to stuff capacitors under the bonnet.

 

[audiodon]

FalconEddy,
I often use boutique caps only in the final output stage and only in units that I think will be good enough to show the difference for systems that will get critical listening as follows:
Jensen Copper Foil in Oil - Fisher X-101-C (7591, cathode biased). Slightly bloomy but truly voluptuous and forgiving. Does nothing wrong.
Mundorf Silver in Oil - Fisher X-1000 (EL-34, fixed bias). More modern sounding but without the loss of midrange while either end is extended.
Mundorfs were also used in the Masterpiece Citation II amp I bought from Goldenpath. That amp has the best multidimensional imaging I've experienced, exceeding the Boulder SS amps and Magico Q5s at Goodwin's high end. I don't have a preamp to do it justice yet.

Auricaps showed just how far you can go in both a Fisher 400 and a 500-C. I think they're at the ragged edge, but a resistor update I've tried brings them to another level, so no final word yet on that.

For teflons, I'd want to be using a truly premium unit, not premium from hype, but premium from what my senses tell me. I like to use cases like having heard a symphony in Symphony Hall and a recording done in the same room, though not by the same players. For that live/recorded comparison (I don't have the luxury of experiencing the live event and then doing mix and mastering, so I use the best approximation of room characteristics and behavior.

I've got some Russian K-72s for a scratch build and I bought a deep enough chassis to accommodate them. They're big, so that's why I haven't use them elsewhere.

What are you thinking of putting the Teflons in?

 

[Rod Beauvex]

What are the "lemon drops" mentioned in this thread?

 

[gogofast]

Bear in mind this is all coming from a staunch supporter of a restoring a vintage amp to (as close as the designer intended) the original sound.

when you say "original sound" what do you mean? i'm asking only with intention of maybe knowing what it is, really.

 

[kvflyer]

What are the "lemon drops" mentioned in this thread?

Rod,

This is what a "Lemon Drop" looks like. The picture is only a representative.

 

[FalconEddy]

Whoa Guys, WHOA! . . .

I'm not trying to be a jerk here, however. . .

Have you all forgotten who I am?

Have I really been away THAT long?

I see a new guy or two in the mix here; but, you guys remember me. Right?

Some of these comments look like I just signed up yesterday and I need help with a complete vintage amp restoration or something.

I truly believed my questions were very specific.

I also never stated I was thinking about putting teflons into anything. I asked for opinions about what others thought about a difference in sound from the original coupling caps, if they used teflons to replace them in their vintage amps.

However, it doesn't appear anyone has done this.

Personally, I feel the largest noticeable overall sound differences would be heard in units such as the Fisher 500, Scott 299 series, etc. However, due to heavy cost constraints, you're not likely to come across a set of V-Cap CuTF's or AuraT's coupling caps in these vintage amps due to their assumed inherent value. Plus, having an integrated vintage amp with far too sparkling and articulate a sound might rub purists the wrong way. Well, you know what, that's why they make tone controls. Since the second best thing to boutique teflon appears to be polystyrene and foil (at 1/10 the price), I may just go that route and be the first in line to start a trend (if my ears agree). Yes, I'll publish my findings; otherwise, there can never be a trend.

Most polyester film and foil or metallized polyester caps will give close to the 'original sound' (the sound the designer had in mind when the unit was produced) back to these 60's vintage amps. As long as you're not sporting a set of Sonicap Gen I's in there (unless bypassed with something else to mellow them out), you're good in my book. After all, it's YOUR EARS, right? And listening tastes are highly subjective.

. . Falcon

 

[audiodon]

I haven't used teflons yet. I haven't developed the financial courage. Also, comments about the identifiable teflon sound has kept me heading towards premium PIOs, and heading towards Duelunds, at least so far.

I do think that the unit has to be good enough to justify boutique caps of any stripe. I don't know if the teflons would show off what they can do in a receiver, and I say that as a dedicated fan who's restored well over a dozen Fisher receivers. I'm still experimenting with pair-matched carbon film resistors in certain critical spots and tube rolling.

I'm heading towards increasing the cap quality as the circuitry decreases. I also think that even having a system that will reveal enough that you can isolate glare or hash has not happened yet for many on this audio journey.

 

[FalconEddy]

I haven't used teflons yet. I haven't developed the financial courage. Also, comments about the identifiable teflon sound has kept me heading towards premium PIOs, and heading towards Duelunds, at least so far.

I do think that the unit has to be good enough to justify boutique caps of any stripe. I don't know if the teflons would show off what they can do in a receiver, and I say that as a dedicated fan who's restored well over a dozen Fisher receivers. I'm still experimenting with pair-matched carbon film resistors in certain critical spots and tube rolling.

I'm heading towards increasing the cap quality as the circuitry decreases. I also think that even having a system that will reveal enough that you can isolate glare or hash has not happened yet for many on this audio journey.

There ya go! We're on the same page!! :thmbsp:

The truth be known, I was hoping to get at least one person that had done this. In response, I was going to try the single wind polystyrene and foil caps; and check them on an oscilliscope to be sure the shield end was mounted in the correct position. This was one of those experiments in sound versus cost... sort of similar to that 'silk purse' and a 'sows ear' comparison.

A better analogy would be using some lines from the Star Trek IV movie:

Scotty (talking about the 6" thick Plexiglas that Mr. Nichols carries in stock at his factory, and a piece that measures 10' x 60' will withstand the pressure of 18,000 cubic feet of water: "Now suppose -- just suppose -- I could show you a way to manufacture a wall that would do the same job, but was only an inch thick. Would that be worth something to you?

So, I basically wanted to present something a bit different to all the vintage amp rebuilders out there, and follow it up with the 'holy grail' teflon comparison; both sound and price. For most people, it's unobtainium due to that wicked pricing structure for the boutique varieties. The K72's and FT's series from the Russian military simply are not in the same league. Period. Teflon dielectric, yes; and that's where the similarities end. Sound characteristics can easily vary from cap to cap. They are NOT junk. They're just not consistent enough for me to consider using as a comparison, and I'd never use them as a reference cap. The weird thing is that I've always really liked the K40Y's, and always recommend them for coupling caps when people are looking foranother choice to polyester or polypropylene. Even the K42Y's are ok. I'm just not 'on board' with those damn K72 and FT teflons.

. . Falcon

 

[derekva]

Personally, I feel the largest noticeable overall sound differences would be heard in units such as the Fisher 500, Scott 299 series, etc. However, due to heavy cost constraints, you're not likely to come across a set of V-Cap CuTF's or AuraT's coupling caps in these vintage amps due to their assumed inherent value. Plus, having an integrated vintage amp with far too sparkling and articulate a sound might rub purists the wrong way. Well, you know what, that's why they make tone controls. Since the second best thing to boutique teflon appears to be polystyrene and foil (at 1/10 the price), I may just go that route and be the first in line to start a trend (if my ears agree). Yes, I'll publish my findings; otherwise, there can never be a trend.

WRT the Fisher 400/500/800 series, my tastes tend towards using Russian K40Y-9 caps between the driver/phase splitter and power tubes and poly Mallorys elsewhere.

Of course, as I implied earlier, I'm a notorious tin-eared cheapskate. :thmbsp:

-D

 

[BuzzK]

I'm building a 417A based phono stage from scratch. I normally use the brown PPs from Mouser, Orange Drops(tm), or sometimes Auricaps(tm) or other "boutique" caps. This time I ponied up for a pair of Ampohm aluminium foil and paper in oil caps for $24 each, which chafed my wallet. That's definitely the most I will ever pay for a cap, (so I guess I'll never be able to participate in your test if Teflons(tm) run more than that).

A good read is Steve Bench's test results: http://greygum.net/sbench/sbench102/caps.html

Or another guy who did a fairly broad study using boutique caps in a crossover, has several Teflons in the mix:
http://www.humblehomemadehifi.com/Cap.html

The concept of "the sound that the original (vintage) tube amplifier desired" is a foolish anachronism. The design engineer usually got the sound that the accounting department wanted, and there were not a ton of choices. Boutique caps are a more recent phenomenon, driven by the penchant of audiophiles to pay exponentially for incremental "sonic gains."

The polys usually brighten up a tube amp a little bit (some people say that is a bad thing). I suspect that a cap upgrade improves the performance vs. stock in many if not most situations. Heck, if you really want something authentically vintage, then go throw out your LCD screen and watch an old black and white CRT . . .

One bit of advice that seems to work for me: If you believe that caps have a sonic signature, don't use the same type throughout and amp. Mix 'em up a bit.

Buzz

 

[FalconEddy]

I'm building a 417A based phono stage from scratch. I normally use the brown PPs from Mouser, Orange Drops(tm), or sometimes Auricaps(tm) or other "boutique" caps. This time I ponied up for a pair of Ampohm aluminium foil and paper in oil caps for $24 each, which chafed my wallet. That's definitely the most I will ever pay for a cap, (so I guess I'll never be able to participate in your test if Teflons(tm) run more than that).

A good read is Steve Bench's test results: http://greygum.net/sbench/sbench102/caps.html

Or another guy who did a fairly broad study using boutique caps in a crossover, has several Teflons in the mix:
http://www.humblehomemadehifi.com/Cap.html

The concept of "the sound that the original (vintage) tube amplifier desired" is a foolish anachronism. The design engineer usually got the sound that the accounting department wanted, and there were not a ton of choices. Boutique caps are a more recent phenomenon, driven by the penchant of audiophiles to pay exponentially for incremental "sonic gains."

The polys usually brighten up a tube amp a little bit (some people say that is a bad thing). I suspect that a cap upgrade improves the performance vs. stock in many if not most situations. Heck, if you really want something authentically vintage, then go throw out your LCD screen and watch an old black and white CRT . . .

One bit of advice that seems to work for me: If you believe that caps have a sonic signature, don't use the same type throughout and amp. Mix 'em up a bit.

Buzz

Yes, I know.

I wrote an article about how the true vintage sound of the 60's came about. It basically described the plight of the audio design engineer. How he had limited choices, monkey-see monkey-do selections in some cases (with competitors), trying to tune a stereo circuit without being 100% sure if these same parts would be used (because the contracts weren't signed yet), and trying to explain technical and electrical reasons for that extra $9 that was absolutely necessary to get a UL listing that kept falling on deaf ears in the accounting department.

Of course, my insight was specific to a place in Maynard, MA; but, I have a feeling this was most likely an industry standard operating procedure for a while.

I have been to the links you provided on a few occassions to compare notes.

. . Falcon

 

[Renslipevol]

If your going to want to notice something different, and who wouldn't be wanting that if you spent $24 dollars on one(just bugging you), your going to. Its all subjective. My Scott 222B has seen 3 different caps, stock illinois, inexpensive films, and K40Y's, and I can honetly say I didn't notice a thing change. In my opinion, tubes make a bigger difference than caps do. But I would be a liar if I didn't say that I use russian k40's for almost everything just to keep me sane, because I think they are the best russians can buy. Literally. I think any capacitor made these days far exceeds the accounting departments standards from 40 years ago.

 

[kvflyer]

If your going to want to notice something different, and who wouldn't be wanting that if you spent $24 dollars on one(just bugging you), your going to. Its all subjective. My Scott 222B has seen 3 different caps, stock illinois, inexpensive films, and K40Y's, and I can honetly say I didn't notice a thing change. In my opinion, tubes make a bigger difference than caps do. But I would be a liar if I didn't say that I use russian k40's for almost everything just to keep me sane, because I think they are the best russians can buy. Literally. I think any capacitor made these days far exceeds the accounting departments standards from 40 years ago.

Now that should raise some eyebrows! But I am of the same opinion. So, if anyone wishes to hurl harpoons, I will be on the receiving end as well