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Topic: New Caps for a twin reverb- suggestions |
Steve Waltz
From:
USA
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Posted 30 Jan 2006 5:42 pm |
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I'm replacing the power caps on a non master volume twin reverb. It currently has Mallory caps 3 20uF/600 V.D.C and 2 80uF/450 V.D.C.
I'm going to use Sprague caps on it. I understand that these are a good quality and sound like orignials. I have heard of some more expensive oil and paper caps or something like that. Is there a big difference in sound when going to the higher end caps. I'll be doing the smaller caps later and so I wanted to find out if I should use something better there as well.
Thanks,
Steve |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 30 Jan 2006 5:51 pm
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The Spragues will be fine for the high-voltage caps.
For signal caps, many techs now use polypropylene. Ken or Brad can advise which ones are best buy for the sound. Some of the botique types run $20 each. The Sprague "orange drops" are what I use, cheap, and a decent sound.[This message was edited by Donny Hinson on 30 January 2006 at 05:55 PM.] |
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Ken Fox
From:
Nashville GA USA
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Posted 30 Jan 2006 6:07 pm
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I go with Donny on the Oramge Drop caps, good as they get for my ear!
For filters use the TVA- series from Mallory. You can get them at Mouser.com
Here are some caps I used on a recent Twin job,
2 filter cap 100 ufd @ 450 WVDC TVA1620
2 bias filter cap 100 ufd @ 100 WVDC TVA1346
3 filter cap 20 ufd @ 500 WVDC TVA1906
5 cathode bypass 25ufd @ 50 WVDC TVA1306
1 cathode bypass 5ufd @ 50VDC TVA1303
[This message was edited by Ken Fox on 30 January 2006 at 06:08 PM.] |
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Tom Quinn
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Posted 31 Jan 2006 5:46 am
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Do NOT use orange drops in any signal path, period. they will thin out the tone of your amp, and make it sound grainy, like it has a head cold.
It is worth the time and effort to find oil caps such as NOS Vitamin Qs, Aerovox or some of the rebranded Mallorys.
I just had my 66 Twin Reverb rebuilt by an absolute master of all things tube. He does this as a hobby, and uses a different version of the orange drops in the power section. He replaced the .047s with some stronger caps, and left the rest stock.
The normal channel sounds like a tweed high-power Twin, and the reverb side sounds just beautiful. Of the at least 100 amps Through my hands, I've probably owned multiples of every desirable amp ever made since I started playing electric guitars in 1964. This Twin is right up there with the best of the best I've ever owned.
YMMV of course, and I mean no offense to the posters above... :- ), I just hate the tone of orange drops... -L- |
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Andy Zynda
From:
Wisconsin
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Posted 31 Jan 2006 6:21 am
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I like the orange drops, about half the time. On some amps, they will do exactly what the above poster described. They can sound sterile. If your twin has the Blue Tubulars in there, LEAVE THEM IN!!!
1) They sound great. 2) They last nearly forever. 3) There are a good number of vintage amp techs that will pay HUGE dollars for your old ones if they can get them. The reasons are posted above.
I have seen single .1's or .047's go for as much as $20 apiece.
I've been building, restoring, modding and de-modding tube amps for almost 5 years now, and I learned the hard way. The only signal caps that I will replace right away, are the "turds". These are brown, non-shiny caps with yellow text. They sound as bad as they look. There are some brown shiny caps that are fine. The dull ones are garbage.
Just my 2 cents.
PS! If you pull out any blue tubulars, let me know! I'll buy them!! (for a reasonable price, o' course...)
-andy-
[This message was edited by Andy Zynda on 31 January 2006 at 06:22 AM.] |
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Ken Fox
From:
Nashville GA USA
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Posted 31 Jan 2006 7:15 am
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The coupling caps can "last forever" or they can start to pass DC! The primary thing I do is check that they are blocking DC voltage! If not you will have problems that can variy from scratch tone pots to erractic tube bias on the power tubes.
A lot of folks do not like the brown caps and I have changed them out. The blue ones are really sweet, as Andy said .
I have had great tonal results with Orange Drops and happy customers using them! They are very clean in tone, I agree. Not for your average blues tone for sure!
My main concern with filter caps is reliablilty. I do not see where they affect toone, they are not in the signal path! A poor one with low filtering ability will certainly add to the amps overall bad sound, as the audio will be riding on a wave left over from the filters! Their job is to provide a nearly flat DC voltage and also to prevent interstage coupling!
When one of the preamp filter goes south the amp can howl like a dog when a tone control is advanced! If these were not at the plates of the preamp tubes, signal would go back to the previous stages!
[This message was edited by Ken Fox on 31 January 2006 at 07:15 AM.] [This message was edited by Ken Fox on 31 January 2006 at 07:20 AM.] |
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Jay Fagerlie
From:
Lotus, California, USA
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Posted 31 Jan 2006 8:27 am
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Ken,
You posted "two bias caps"?
Did I miss something?
Jay |
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Ken Fox
From:
Nashville GA USA
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Posted 31 Jan 2006 8:43 am
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| The early Silverface 100 watt had two bias caps at 80uf |
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Jay Fagerlie
From:
Lotus, California, USA
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Posted 31 Jan 2006 8:54 am
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OK, thanks Ken
I have a MV silverface here that has a single 80uf 100V
I'm going to put in a 100uF....I can't seem to get an 80uF...
Have you swapped a 100 for an 80?
I don't see a problem as long as the current draw is within specs....
Jay |
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Ken Fox
From:
Nashville GA USA
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Posted 31 Jan 2006 9:27 am
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I use a 100uf for the 80uf. Both my Master volume schematics (100 and 135 watt) show two filters in the bias area! 2 at 80uf on the 100 watt. 1 at 80uf and 1 at 70uf on the 135 watt.
I will email the schematics to you
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Jay Fagerlie
From:
Lotus, California, USA
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Posted 31 Jan 2006 10:01 am
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Got 'em Ken, thanks
I see what you mean.
I'll take another look and see on this twin sittin' on my bench....
I found it...hanging off the balance pot.
I'll change that one too.
Thanks again Ken,
Jay |
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Steve Waltz
From:
USA
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Posted 31 Jan 2006 10:07 am
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Thanks for all of the help. Two last quick questions. I did notice the comment about two bias caps. This amp is an early silverface twin non master volume. It has been black faced. I see one bias cap and it is currently at 25 MFD 50VDC. I ordered the same thing to replace it. Should I have gone to a higher VDC? I'm not sure where the other one would be?
All of the .1 uf/400 caps and the .47's are black spragues with orange writing. I tested a few as much as I can and they seem to be working. I just ordered a full matched set of JJ tubes. After I replace the power caps and tubes, if the amp is quiet and seems to be running at a good volume, should I just leave these sprague caps alone?
The board that all of the caps and resistors are attached to in my vibrosonic is a black board. It looks like all of the other fenders that I have seen. This Twin that I am working on has a light brown board that has little holes evenly distributed over all of it. The resistors and caps are attached to a little poles, like the eye of a needle with the top cut open, that comes out of the board. Just for my Fender history lesson, what is that? Is that an aftermarket board or was that something that fender used.
Thanks again,
Steve |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 31 Jan 2006 12:33 pm
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For electrolytic filter caps, I always choose the Sprague Atoms. They seem to be excellent. But for signal cap's, that's a big can of worms. The 716p Orange Drops are nice if you want a bright, clear, and snappy sound. I like them in the phase splitter section and sometimes in the coupling and tonestack positions, but they are indeed a harder sound. One thing that needs to be said is that high voltage signal caps need time to break in. A well broken in Orange Drop sounds worlds warmer than when you first install them. You just can't recap and evaluate right away. It literally takes months of use to really know.
My Fender amps usually have 3 different kinds of signal caps in them. If you go to Angela Instruments (www.angela.com), they carry a nice variety. The old stock blue tubulars do sound warm and full, but they're not real detailed. That can be a good thing. The Angela tin caps have that same full warmth, but with more clarity and detail, but not brightness like the OD's. The Angela Sequa paper in oil types sound great. They're very musical, great midrange, very detailed, but smooth like buttah. I once had my pair of Deluxes side by side. One was a '66 with the Angela tin caps and also a '68 with paper and OD's in it. The '66 was dark and warm with a sweet top end. The '68 was real clear and cut thru more aggressively. The tin caps are my fave's for the .1 and .047 on the tonestack. Rich midrange, real lush. I generally try to keep a Fender amp dark and mellow and then use Orange Drops here and there to liven it up a bit. I always seem to gravitate toward film/foil caps. Some people really like the metallized film polyester (mylar) and polypropylene types.
An expensive, but wonderful sounding cap is the Audiocap Theta. Very clear and detailed, but still so rich and smooth that the brightness doesn't dominate. Also, in a Fender, I will always replace any ceramic cap in the direct signal path, including the 250pf treble cap. I almost always use a silver mica in that position. So it's all about experimentation and matching. If you use a JBL with it's metal dustcap, then the Orange Drops can easily get too bright, but for some tele pickers, it's THE sound. I like the Angela tin caps with JBL loaded amps. Go nuts and don't get zapped in there.
Brad |
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Ray Minich
From:
Bradford, Pa. Frozen Tundra
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Posted 31 Jan 2006 1:12 pm
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Brad, is the Break-In period marked by a change in dielectric absorption, a change in leakage current, or change in something else?
Thanks. |
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J Fletcher
From:
London,Ont,Canada
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Posted 31 Jan 2006 1:59 pm
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Somebody has already replaced the filter caps at some point, as those don't sound like the original values to me. Check out the date code on the big filter caps, and if they are fairly recent, leave well enough alone.
Your description of the circuit board indicates that it has also been replaced...Jerry |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 31 Jan 2006 6:24 pm
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Ray, I really have no idea. I'd just call it mojo. Audible mojo. It's like all the new parts need time to make friends with eachother and get loosened up. I know it's a highly technical explanation, but it's all I got.
Brad
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