I've just recapped my old mark IIb

Pre Recto days. Boogie modified Fenders, Mark I-IV, Dual Calibers, etc

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dodger916
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Re: I've just recapped my old mark IIb

Post by dodger916 » Fri Jan 22, 2016 7:06 am

stokes wrote:
dodger916 wrote:A word on cap jobs: While it's true old, caps do wear out, rob tone and can cause damage if they leak or burst, it's not necessary to replace ALL the caps in an amp. Filter and coupling caps are the highest risk/greatest impact, but the other smaller caps don't always need to be replaced. For instance, I recently bought a 1966 Fender Pro Reverb that had the filter caps and coupling caps replaced, but the other smaller caps in the tone stack are within spec and original. A tech I spoke with (who does tons of work on old amps) said replacing all caps can rob the amp of its "mojo".
I wouldnt change coupling caps unless they are leaky,especially in a vintage amp.The value of the coupling cap shapes the signal as the it passes thru each stage.Bigger caps,i.e. .1mfd will pass more low frequencies and less highs than a .02mfd.If you change the coupling caps just because they are old and not leaking,you will absolutely change the tone and not neccessarilly for the better.In a vintage amp,if a cap or resistor value has drifted some,replacing it with an exact value will affect the sound of the amp.If the amp sounds good,leave the coupling caps alone,unless they are leaky.
Thanks, Carl. By the looks of my Pro Reverb, the coupling caps may be original. The amp still has the "blueberry" caps, now 50 years old, and sounding great. Hope upstate is treating you well, my friend!

Mk IIA->C+ DRGX head "Cold Sweat" in GTS shell
1966 Fender Pro Reverb
DC-3 head
Orange Dual Terror
EVM loaded Thiele; MS-12 1/2 back
71 SG; 72 Tele; 76 White Strat; 77 LP Custom; 81 Goldtop; 05 Am Dlx Strat; 11 G0 plaintop

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stokes
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Re: I've just recapped my old mark IIb

Post by stokes » Mon Jan 25, 2016 9:23 pm

Pro's are awesome amps,Frank,when'd ya get it?Upstate is cool,still settlin' in,but its comin along.

dodger916
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Re: I've just recapped my old mark IIb

Post by dodger916 » Tue Jan 26, 2016 5:21 pm

stokes wrote:Pro's are awesome amps,Frank,when'd ya get it?Upstate is cool,still settlin' in,but its comin along.
I found it on eBay. The seller lived near Oneonta, and coincidentally my son had a high school soccer playoff game in Oneonta. He was a neat guy around 60, having worked in the City for many years as a recording engineer for some big names. He won 5 Grammys! I demo'd it for about 20 minutes and really really liked it, but he wouldn't budge on the top-of-the-market price so I said I'd think about it. The auction had no bidders. In the meantime, I got one from Guitar Center (1976?) with Master Volume and pull-pot, but returned it. I was near Albany around this time and stopped-by Highway Music. They had a 1968 "drip-edge" model that I picked-up (7 day return/refund), but it was the 1968 circuit, not the AA165. I liked the Oneonta/eBay one much better; subtle yet profound difference. I called Oneonta before he re-listed it and told him I'd take it. It's such a great amp I'm glad he didn't lower the price! It had a mix of old and new 12ax7s and a pair of EH 6L6s, so I swapped some preamps and tried different power tubes, finally settling on a pair of Groove Tubes GE replicas with earliest break-up. Biased up nicely (a bit cold, ~50%), and sounds great! I also run it with Yellow Jackets. It breaks-up earlier and is fine for practice, but 6L6s are the True Voice.

He bought it from Highway Music, so when I returned their amp we spoke about it. The tech, who works on lots of vintage amps, said he replaced the filter and coupling caps. I opened it up and it's pristine and all original besides the caps he replaced. It has the original Utah speakers, which are fine. I picked up a Jensen C12Q (~20 watts), which I like. It can get nice and growly, but only for living room playing. I put quick-connects on the speaker wires and can run either speaker (Utah or Jensen) or both. It's become my number one, replacing my DC-3, on which I only used the clean channel anyway. Great amps, and not exorbitantly expensive.

Mk IIA->C+ DRGX head "Cold Sweat" in GTS shell
1966 Fender Pro Reverb
DC-3 head
Orange Dual Terror
EVM loaded Thiele; MS-12 1/2 back
71 SG; 72 Tele; 76 White Strat; 77 LP Custom; 81 Goldtop; 05 Am Dlx Strat; 11 G0 plaintop

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Henz
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Re: I've just recapped my old mark IIb

Post by Henz » Wed Oct 03, 2018 6:21 pm

Nice job! Hey, anyone know where I can get a new set of reverb cables for my MKIIC+ long head? Thanks!
MKIIC+
2:90
4x12 Recto Cab w/ Eminence and V30's
Home made 2x12 half open cab w/ Eminence and V30's
Rocktron Patchmate, Rocktron Intellifex, TS10 Tubescreamer

woodbutcher65
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Re: I've just recapped my old mark IIb

Post by woodbutcher65 » Thu Oct 04, 2018 5:53 pm

Anybody with a soldering iron could make up a new set of reverb cables. Easy to do. Or you can buy a correct set from Mesa. They're not expensive.

If you want to make your own, one cable is just an insulated white wire needing no shielding. The other, use Gibson style shielded wire used for wiring up guitars, available from Stewart-MacDonald.


Another vote for Pro Reverbs. I've owned three over the years. All silverface, one "original" blackface circuit and two later ultralinear circuit models.

Some people slam the silverface Fenders for not sounding good but there's some real magic going for the later ultralinear silverfaces. (Look for the 70 watt rating, or 135 in the case of the Twin.) These have a magic to their clean tone that nothing else has. But they don't distort well. Buy them and use them just for that utterly lush clean tone and that is all.

As has been said, unless there's a REASON to do so, the only electrolytic caps that should normally be replaced in periodic maintenance are those in the power supply and that includes the bias circuit caps. Leave the couplers and bypass caps alone.

One additional exception: Randall Smith has an affection for using those GODAWFUL SOUNDING yellow tantalum capacitors in many Mesas. Yes, they do offer a lot of capacitance in a small package, but they sound TERRIBLE and tantalum capacitors always have a limited service life. They go bad by becoming dead shorts and I've found shorted caps of this type in equipment that was not yet 20 years old.

I recommend yanking and replacing all tantalum capacitors with other types. If they're in the audio signal path, you don't want them in there.


Now, if they're part of a switching circuit or other non audio path, there's less need to change them. But they still will go bad at some point. It's the nature of tantalum capacitors. There is yet another exception, and those are wet slug tants. Those look like axial leaded electrolytics and usually have a red seal on them. And they contain liquid sulfuric acid as their electrolyte. They basically can last forever if not subject to voltage beyond their design limit. They are HORRIBLY expensive. Where an electrolytic might cost a dollar, a wet slug tant might cost 25 dollars.

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