Fender 6G15 REverb Unit Recap

[texasaudio]

Hello all,

This is my first post. I live in Texas and have been asked by a friend to recap his Fender 6G15 REverb Unit. I have recapped several AM radios and a Mcintosh C29 preamp. This will be my first Fender to recap.

It looks pretty straight forward, My question is what brand of capacitors should I use. And any suggestions to where I can buy them.

Thanks in advance,

MaTT

[Wittgenstein]

Sprague Atom electrolytic capacitors are worth the few extra bucks in my opinion. You can pick them up from Antique Electronic Supply for about $13.50 for each 40uf big cap. (Antique Electronic Supply)

[David Schwab]

Here's a Vishay/Sprague Atom, 40µF, 250v, for $6.85.

TVA1511 Vishay/Sprague Aluminum Electrolytic Capacitors - Leaded

[Chuck H]

Atoms are still the standard for recapping Fender units. I think this is because most Fender amps didn't use multi cap cans and you can keep a reasonably stock layout with axial lead caps. Not too many axial lead caps being made so the Spragues rise to the top pretty fast. But...

I've decided to start using a different cap in my own amps because the Atom's haven't been performing well in my last couple of builds. I've been reading many similar positions from other posters too. What's very telling is that it's difficult to get any real specs for the Atom caps. Common knowledge dictates that if a MFG doesn't post a particular spec for a component, it's probably because that component under performes in that area. And Sprague offers very few specs for the Atom caps.

A lot of guys are switching to Panasonic or Nichicon products. And for good reason if you look at the specs. Of course it's more trouble to retrofit radial lead caps where axials are typical, but that's up to you.

I'll be trying the Nichicon PW series caps on my next build.

JM2C

[big_teee]

Here's a Vishay/Sprague Atom, 40µF, 250v, for $6.85.

TVA1511 Vishay/Sprague Aluminum Electrolytic Capacitors - Leaded

How do you always find what your looking for on that site?
I have Ahellofa Time on there.
Was looking for Can Caps, didn't find any!
T

[Wittgenstein]

Here's a Vishay/Sprague Atom, 40µF, 250v, for $6.85.
TVA1511 Vishay/Sprague Aluminum Electrolytic Capacitors - Leaded

Thanks for the link David. I will have to start ordering from Mouser apparently.

[dai h.]

250V rating, so (unless meant to be put in series) if those are for the rect. out, then they look too low

[Wittgenstein]

$12.11 for 450 volts.

[Tom Phillips]

The Sprague Atom series has been on their "Not recommended for new designs" list for many years. That's a warning that they could discontinue production at any time. They must still be making money on the line because they keep them in production.

The Atoms do have a certain cool vintage size factor and I like the nice long sturdy axial leads. Other than that I don't think they are anything special anymore. If you cut one open you will find the guts of a small cap. That by itself doesn't mean it is a bad design. They could just be using modern materials which result in a physically smaller capacitor. Probably the guts from one of their other cap lines. They put the small guts inside the old large package for marketing and replacement form factor reasons. The amount of empty air space inside varies with each part value. The problem that I have experienced with this is that the guts are not always well secured inside the can. I have received new Atoms that rattle and that can't be good.

Now you can understand why a 20uF/500V Atom seems so relatively light for its physical size.

[texasaudio]

Thanks to all the replies for the info. What type of cap is recommend for the non electrolytic caps? And help me remember is it +200% and -50% for substituting cap values?

Thanks,

Matt

[David Schwab]

How do you always find what your looking for on that site?
I have Ahellofa Time on there.
Was looking for Can Caps, didn't find any!
T

I guess I spend way too much time there!

I also get the big honking' catalog in the mail, which is much fun to peruse.

[Wittgenstein]

Mallory or Orange Drop seem to be the standard for non electrolytic capacitors. I have used both and have not noticed a big difference, but I am starting to prefer Mallory.

As for substituting different values caps to change the tone, I have read in several books that you need to either double the value or half it to make and audible difference. So instead of using 0.1UF/630V capacitor, you would go up to 0.22uf or down to 0.047uf. May I ask why you want to change this vintage beauty?

[Tom Phillips]

…And help me remember is it +200% and -50% for substituting cap values?...Thanks, Matt

Matt,
That may be and old rule of thumb when you don’t have the specified value available and you need to get a piece of equipment working with whatever you can find. However, when rebuilding a vintage piece of equipment I think there are two ways to go.
1) Use the original specified values and accept the performance that results due to the tolerance of the parts used. The parts in the old amps were often ±20% tolerance. This meant that there could be audible differences in the sound between amps of the same model because of the way the sum total of all the parts interact. The differences may make one amp sound “good” to you and the other sound “good” to your customer. In addition, all the tolerances could line up to produce sweet spot performance or a dull sounding amp. Again, there is the matter of personal preferences, playing style and type of music preferred. The new parts that you buy will most likely be ±5 or 10% tolerance and that will be fine.
2) Do #1 but tweak a few values per a known mod or per your personal preference if you have the knowledge.

Personally I don’t think that you can go wrong using the stock values in a known good design like the 6G15. On another personal note, I don’t necessarily do wholesale recapping of coupling & tone caps when I overhaul an amp. If I’m working on a Fender with the original blue molded tubulars I’ll check them but I know that it is rare to find a bad one. If the old Fender has yellow Astrons then, from experience, I know that I’ll save time by replacing them all from the get go.

I like to use the Mallory’s because the true axial tubular form is nice to work with and they perform well. I use orange drops too but they are not the magic mojo that newsgroup discussions profess. There are also many different types of “orange drops” and the difference between the types is probably greater than the difference between a given type of orange drop and a Mallory 150 series.

The most important thing is to use decent parts of the correct value installed with good workmanship and service the mechanical grounds, pot wipers, tube socket & jack contacts at the same time. You also look for mistakes introduced by past service or left over from the original factory build.

Hope that helps,
Tom

[jrfrond]

For higher quality in a slightly smaller can size, I've been switching over to F & T caps, available from CE Distribution. Do NOT, however, purchase their 2 x 25/50 dual cap for use in Fender amps that use dual cps. They are HUGE!

[Sweetfinger]

Thanks to all the replies for the info. What type of cap is recommend for the non electrolytic caps? And help me remember is it +200% and -50% for substituting cap values?

Thanks,

Matt

I wouldn't replace any non-electrolytic in a vintage amp unless it specifically tested bad. I'm not sure where you got the +200/-50% thing for value. You should use same or better tolerance and identical value. Even 5 or 10% is audible. -50/200% will result in a really different sounding/responding/not working unit.
For the big can cap, you'll have to look through the selection at Antique Electronic Supply/CE Distribution. It isn't a large selection.