Fender Deluxe AB763 vs Fender Deluxe Reverb AA763 Schematic Filter Cap question

[mikepukmel]

Hi All,
I have schematics for AA763 Deluxe and AB763 Deluxe Reverb.

The Deluxe Reverb has two 16uf 450v electrolytic caps in parallel right before the standby switch.

The Deluxe (no reverb) has one 16uf 450v electrolytic cap right before the standby switch.

Since the rectifier and transformer and choke are the same, can I use two electrolytic caps in a non reverb build? Ive read someplace that additional caps would 'firm up the bass response', this would bring the first cap the tube sees to 32uf.

The GZ spec sheet says max 60uf, is this still far enough from that point?


Thanks!
Mike

[Enzo]

MAke it 40uf, 32uf would be an odd value to find, unless you want to pay collector prices.

[mikepukmel]

MAke it 40uf, 32uf would be an odd value to find, unless you want to pay collector prices.

Thanks Enzo. COuld I just use 2 x 16's like they did on the original reverb cap boards?

[Leo_Gnardo]

Thanks Enzo. COuld I just use 2 x 16's like they did on the original reverb cap boards?

Crikeys... 16's another tough find. Maybe you can get caps marked 16 but more than likely what they really are is 20 or 22 uF, currently common values specially marked to appeal to those who will pay a LOT of money to have what they think are "accurate values." Not that anyone would be so devious, just to take your money.

Put in a pair of 20 or 22 uf 500V caps, be done with it, never have to worry again for a couple decades. Or a 47/500. Really, the amp doesn't care and if your ears can tell the difference then count yourself very very very special. (Put smiley thing with halo overhead here.)

If you must dare to be antiquated, Antique has F&T 16/475 and Sprague Atoms, same at 2.4 times the price. Knock yourself out.

[mikepukmel]

Thanks, yeah tube depot has F&T's
https://tubedepot.com/products/f-and...many-16uf-475v
5.00 a piece. The sprague atoms are out of this world, like 14.00 the cheapest I could find.
Is 5.00 a piece OK? 16's and 22's are about the same price.

[Enzo]

Look at old Fender schematics, there will be some notes on them. One is that all readings are to be considered within +/-20%. Not only that, filter caps back then had typical tolerances like -20/+80%. So a 16uf cap might have measured 20uf anyway, and be perfectly fine. These are just guitar amps, not NASA space computers. There is no precision in the parts, nor really is there a need for precision.

The reason you can still find 8uf and 16uf caps at these voltages is because someone figured they could make money selling them to amp fans. They used two 16uf because it was cheaper than one larger cap at the time. You of course could use two 16 instead of one 32 or 40, but why? I have a drawer of 22uf 500v caps and I would reach into that without hesitation before I'd look for any 16uf caps.

[mikepukmel]

Look at old Fender schematics, there will be some notes on them. One is that all readings are to be considered within +/-20%. Not only that, filter caps back then had typical tolerances like -20/+80%. So a 16uf cap might have measured 20uf anyway, and be perfectly fine. These are just guitar amps, not NASA space computers. There is no precision in the parts, nor really is there a need for precision.

The reason you can still find 8uf and 16uf caps at these voltages is because someone figured they could make money selling them to amp fans. They used two 16uf because it was cheaper than one larger cap at the time. You of course could use two 16 instead of one 32 or 40, but why? I have a drawer of 22uf 500v caps and I would reach into that without hesitation before I'd look for any 16uf caps.

Thanks Enzo. getting there. I looked through a whole bunch of electronics parts sites. Some have +/- 20% and some are -20/+75 a few -20/+50. The consumer "a couple at a time" prices all seem to be in the 3.00 to 5.00 range, unless its those Sprague Atom's, some are just out of sight, like 13.00 or 15.00. For one cap! Eek.

[pdf64]

I suspect that Enzo's point isn't that you too should source caps with the same tolerance to nominal value spec as those which would have been available commercially in the early 60s.
Rather that the precise value isn't critical, because the actual value of a cap could have been way different from nominal, more likely higher, as the tolerance is lopsided, and so a modern 22uF cap is a perfectly valid part to use in a vintage design that calls for 16uF.
As the 16uF caps that were available then could have actually measured 22uF or more yet still been 'in spec'.

[Enzo]

Exactly.^^^^ I mentioned tolerance to show that in the old days those huge tolerance parts were what they used, so the actual capacitance of each cap could be all over the map. SO it is pointless to worry about the exact value from the old drawing, because the real amp could have had a wide range of capacitance there. So I stock 22uf 500v (and also 450v), while I don;t stock odd ones like 8uf or 16uf or 32uf.

[mikepukmel]

Cool, thanks. Found lots of 22, 25 etc value caps here and there. Now, only looking for a source that doesn't force me to buy 500 at a time. (My wife would kill me if the freight truck showed up and I filled up the garage with 20,000 capacitors for my amp build)

[Leo_Gnardo]

Found lots of 22, 25 etc value caps here and there. Now, only looking for a source that doesn't force me to buy 500 at a time.

You said you're getting parts from Hoffman, good outfit! I'm sure they have the filter caps you need at a good price and minimum quantity = 1.

FWIW sometimes I've gone price shopping for caps & other stuff, found those parts places where you have to buy hundreds of parts, or hundreds of dollars worth of each or else "no sale." What a hassle, but now I'm hip to them & of course don't bother searching their catalogs.

There's a cost advantage to minimizing the number of places you go shopping for your project. Shipping will kill ya! Some of my customers who kit their projects from here there & everywhere spend $100-200 on shipping before they're all done.

[Enzo]

My first stop part shopping for caps was Mouser, and I never had to buy 500 or even 50. Same at Digikey. Some of the higher voltage caps I went to our industry specific suppliers like Antique Electronic Supply, who also had no minimum number of caps to buy. I used CEDist, their wholesale wing, as a dealer. I used to buy at least ten at a time, but I ran a shop. But I could order just one of a part if that was all I needed.


The places with 500 part minimums or $100 line item minimums are large industrial suppliers, and aren't set up for tiny little orders. WHen you google search for parts, you may find those suppliers. ANy place that has "click for quote" buttons by items is not going to serve you. If I just want to know something about a part, I use google on the part number. But when I am shopping, I pick the supplier first, and then specific items search on their web site, and that eliminates the Avnets or whoever that have large minimums.


Shipping is an important concern. I make up a grid on a page of paper: parts down the left, columns for the suppliers. I want to get parts in as few orders as possible. SO sometimes I don't take the lowest cost. I might find a cap is 20 cents cheaper somewhere, and I want 20 of them. That would be a $4 saving. But if I take into consideration that to save the $4, I incurred another $11 in shipping, I pay the higher price at wherever I was buying the rest of my order.

[mikepukmel]

My first stop part shopping for caps was Mouser, and I never had to buy 500 or even 50. Same at Digikey. Some of the higher voltage caps I went to our industry specific suppliers like Antique Electronic Supply, who also had no minimum number of caps to buy. I used CEDist, their wholesale wing, as a dealer. I used to buy at least ten at a time, but I ran a shop. But I could order just one of a part if that was all I needed.


The places with 500 part minimums or $100 line item minimums are large industrial suppliers, and aren't set up for tiny little orders. WHen you google search for parts, you may find those suppliers. ANy place that has "click for quote" buttons by items is not going to serve you. If I just want to know something about a part, I use google on the part number. But when I am shopping, I pick the supplier first, and then specific items search on their web site, and that eliminates the Avnets or whoever that have large minimums.


Shipping is an important concern. I make up a grid on a page of paper: parts down the left, columns for the suppliers. I want to get parts in as few orders as possible. SO sometimes I don't take the lowest cost. I might find a cap is 20 cents cheaper somewhere, and I want 20 of them. That would be a $4 saving. But if I take into consideration that to save the $4, I incurred another $11 in shipping, I pay the higher price at wherever I was buying the rest of my order.

Thanks Enzo!

[mikepukmel]

My first stop part shopping for caps was Mouser, and I never had to buy 500 or even 50. Same at Digikey. Some of the higher voltage caps I went to our industry specific suppliers like Antique Electronic Supply, who also had no minimum number of caps to buy. I used CEDist, their wholesale wing, as a dealer. I used to buy at least ten at a time, but I ran a shop. But I could order just one of a part if that was all I needed.


The places with 500 part minimums or $100 line item minimums are large industrial suppliers, and aren't set up for tiny little orders. WHen you google search for parts, you may find those suppliers. ANy place that has "click for quote" buttons by items is not going to serve you. If I just want to know something about a part, I use google on the part number. But when I am shopping, I pick the supplier first, and then specific items search on their web site, and that eliminates the Avnets or whoever that have large minimums.


Shipping is an important concern. I make up a grid on a page of paper: parts down the left, columns for the suppliers. I want to get parts in as few orders as possible. SO sometimes I don't take the lowest cost. I might find a cap is 20 cents cheaper somewhere, and I want 20 of them. That would be a $4 saving. But if I take into consideration that to save the $4, I incurred another $11 in shipping, I pay the higher price at wherever I was buying the rest of my order.

I spent the past few weeks creating web shopping carts at a few (3-5) vendors. No matter how hard I tried, I can't get all of one type of component at one supplier (e.g. all resistors). E.g., Vendor X has all the resistors, except for 10 meg. Vendor Y is the only one that has all of the CTS pots with metal shafts. Vendor Z has some metal shaft, some plastic (plastic shaft pots in a guitar amp? No way), but everything else they sell is 50% more than any other vendor. Its a great learning experience anyway, encouraged me to learn (and continue to learn) a lot more about component types than I knew before. Awesome to have you gurus suggestions and comments!

[mikepukmel]

Has anyone used MIEC electrolytic capacitors? As far as I can tell, its very (very) small company in Taiwan, that makes pretty good specialty capacitors. They have guitar amp spec caps in excellent prices compared to the extortion charged by Vishay/Sprague. I sent a few questions out to resellers about getting some MTTF charts, but haven't heard back yet. My guess is that MIEC doesn't provide that info. But its not a new company, been around for decades. Someone out there should have compiled MTTF charts?