So I am thinking about recapping my 68 NOS metro plexi build.....What brand caps? Update 1/22/25

[harddriver]

Cool. Transformers and voltage? Just curious, my Metro '68 just never satisfied but my Metro '69 slays and I'm thinking of cloning my clone just because it sounds so good. Tryin to figure what made the difference.

Power and Output transformers are Heyboer, The power is the dagnall clone dual voltage Metro and the Output Transformer is the Dagnall 1998C Heyboer clone. This amp is biased to run at 90ACV all the time. B+ is running 355DCV @90ACV. I'm guessing that I never experienced really bad graininess from the F+T's in the main/screens/PI because the preamp was running that 32uf/32uf Erie cap. Who knows? Sometimes it's just a roll of the bones on how an amp turns out....

I had a Merren power and output transformer set sitting here for it for a long time, but I never did swap out the Heyboers and sold the Merrens.

The amp has aged well and seems to sound better now than when I first put it together.....maybe my hearing is just going........

For the 69 build I used a Magnetic Components/Classictone 40-18053 power transformer, the model with the copper band across the top of the lamination stack( this was the model designed to run cooler than the regular PT that all seemed to run hot, they kept saying it was normal...I did not agree so I ripped out the one that was running hot and the bias would drift as well) and the Heyboer 1998C OPT in my 69 build and that amp was a really great sounding SL and could do it all. Everything in the 69 build was NOS, Iskras, RS Caps, NOS paxolin reddish boards like they used in 69 and NOS Cinch ceramic 9 pin tube sockets. Here are some pics of the 69 build. I had two channels on the 69 amp, you had teh standard bright channel of the Superlead through the bright channel jacks and when plugged into the normal channel jacks you had the bright channel of a Super Bass but with a SL 33K/560pf tonestack. The 69 was biased to run at wall voltage all the time, it was my plug and play amp.

 

[harddriver]

Here are some pics of my 68 plexi build, it's nothing exciting really, I tried quite a few Ed spec things in it until I arrived back at stock plexi specs except I'm running 100uf on the PI. It has the 50K midpot, no gain mods and I recently removed the 25uf cap I had in parallel with the .68uf on V2 as I just don't need the extra gain. I run all NOS Sylvania 12ax7's and 6CA7's in it. It's running 820/250uf V1A 2.7K/.68uf(philips polycarbonate chicklet) V1B 820/.68uf V2A, NFB is 47K on the speaker jack like a Super Bass. The 3rd speaker jack is for my Suhr Iso line out to feed my W/D/W setups. All in all it does the Ed spec thing well and EQ'd differently it will do all the other classic Marshall plexi tones but I built mostly for all Ed all of the time.

 

[SpiderWars]

Here are some pics of my 68 plexi build, it's nothing exciting really, I tried quite a few Ed spec things in it until I arrived back at stock plexi specs except I'm running 100uf on the PI. It has the 50K midpot, no gain mods and I recently removed the 25uf cap I had in parallel with the .68uf on V2 as I just don't need the extra gain. I run all NOS Sylvania 12ax7's and 6CA7's in it. It's running 820/250uf V1A 2.7K/.68uf(philips polycarbonate chicklet) V1B 820/.68uf V2A, NFB is 47K on the speaker jack like a Super Bass. The 3rd speaker jack is for my Suhr Iso line out to feed my W/D/W setups. All in all it does the Ed spec thing well and EQ'd differently it will do all the other classic Marshall plexi tones but I built mostly for all Ed all of the time.

Looks great. What’s that in the ‘Tremolo model V1 hole’.?

 

[harddriver]

To follow up on the order from ARS the new caps showed up first thing Monday 11/18/24. I think that's the fastest I've gotten anything from California.

Now that's pretty good service in my book!

 

[harddriver]

Looks great. What’s that in the ‘Tremolo model V1 hole’.?

Jose master.

 

[Geo]

Don't fix what ain't broken.

 

[matttornado]

Jose master.

I don't hear much about that....How does it sound compared to the LAR MAR PPIMV? Do the diodes add extra clipping?

 

[harddriver]

I don't hear much about that....How does it sound compared to the LAR MAR PPIMV? Do the diodes add extra clipping?

The Jose master is not a very good master for a plexi amp, the LAR/MAR is superior in a NMV plexi/superlead. However I do not use it as a master in the amp for volume control and have the diodes on a push pull switch. The diodes do some interesting things and do add some compression and clipping artifacts when engaged but are not necessary for for great plexi tone.

How much clipping they provide depends on what value/voltage zener or other diodes you use.

 

[glpg80]

Big fan of ARS myself as well.

Enmity has single 220’s in it and normal 50/50 in the preamp.

For vintage sound I like synergy sozo. I try not to overcomplicate it.

 

[harddriver]

Well... i just got done finishing the full recap job with the ARS caps, mains, screens Phase inverter, I did keep my NOS Erie 32/32uf on my preamp. I also replaced the electrolytic cap on V1A with a new 220uf Vishay/BC cap and installed new Kemet 10uf 200V bias caps. I did install some Iskra resistors 2.7K on V1B, 820 on V1A and my NFB 47K but the values were the same. I had to install new resistors and bias trim pot because the old one was soldered to the legs of the old 10uf bias caps.

I fired it up with no issues and I biased the tubes to almost 60% at 90 ACV. I didn't expect to hear much of a difference but I did. The amp was much more quiet both hum and hiss all around. The amp is definitely less harsh and I almost have to say less GRAINY like alot of guys say F&T caps impart but I hear the difference nonetheless, the amp almost sounds and feels warmer but still with grit, grind and bite, the low end is nice and tight without being clinical running the amp variaced to 90 ACV.

The F+T's were about 17 years old so maybe the were going bad I dunno..... but the new ARS cap made a noticeable difference with the amp.

I got a new ESR capacitor tester so I will test the old ones for capacitance and ESR leakage and let you guys know what the old F&T's tested. This kinda makes me excited to finish up my 1972 that had 30+ year old LCR's and my little 5 watter has 20 year old axial caps that I got ARS caps for that amp as well. I should be finishing up my 72 this week I had to order some replacement 470K's for the mixers and also replaced some missing Iskra's on that amp back to 100% Iskra and redid all grounding to Larry grounding, also with new 50/50uf ARS dual caps for that amp as well.

So I have to admit there must be something about this F&T grainy thing....I didn't want to think so but the proof is in the pudding........all you guys that said so I would say you are audibly vindicated. I am very pleased with how the ARS caps perform and the difference they made in the amp.

 

[glpg80]

F&T are cold, hollow, and uninspiring in Marshall’s. I only used to use them as preamp filter caps in SLO type circuits but don’t anymore. I prefer ARS and Nichicon.

 

[harddriver]

F&T are cold, hollow, and uninspiring in Marshall’s. I only used to use them as preamp filter caps in SLO type circuits but don’t anymore. I prefer ARS and Nichicon.

Hearing is believing.....I agree with your statement.

From a technical aspect I would and did disavow these statements about F&T caps imparting effects as corksniffing.....But I can't deny what I hear with the amp, the amp just sound and feels better...hands down and I've been playing this amp since 2007/2008. The difference is quite real. Funny thing is I have a full F&T recap set for my 67 Fender bandmaster sitting here and I am going to throw them in the garbage and re-order ARS and what ever values they don't have use those new MOD caps that Antique Electronic Supply carries since all the cap for the Bandmaster are axials.

So I am now in the F&T haters club..........I'm glad I didn't have more F&T's in my other amps.

I tested all my caps with my new PEAK ESR70 capacitor tester yesterday so here are the results. Here is the ESR chart which lists the maximum ESR for each cap value and voltage, any readings below the listed Max ESR the cap is still good, if it's close to that ESR reading then the cap is on it's way to being unacceptable.

Here were my results using the PEAK ESR 70 for the F&T caps that I pulled from my 68 plexi: I had to use the 400 volt ratings since they didn't have a 500DCV listing

Dual 50/50: MAX ESR=1.3 ohm 55.68uf ESR=1.2 ohm 55.42uf ESR=0.93 ohm( one side of the PI dual was close to bad but technically still good)

100uf:MAX ESR=0.62 ohm 100.4uf ESR=0.25 ohm Both of these tested good
100uf:MAX ESR=0.62 ohm 102.2uf ESR=0.24 ohm

30uf:MAX ESR=2.8 ohm 29.72uf ESR=0.59 ohm Both of these tested good
30uf:MAX ESR=2.8 ohm 29.78uf ESR=0.58 ohm

Here are the results from the 3 LCR's pulled from my 1972 Marshall 1987 SL that were about 34 years old:

Dual 50/50 PI/Screens cap:MAX ESR 1.3 ohm 49.18uf ESR=1.85 ohm 51.1uf ESR=1.63 ohm ( so both sides of this cap is bad ESR wise)

Dual 50/50 Mains cap:MAX ESR 1.3 ohm 52.27uf ESR= 1.04 ohm 51.98uf ESR= 1.10 ohm (Both sides still good)

Dual 50/50 Preamp cap:MAX ESR 1.3 ohm 49.12uf ESR= 1.19 ohm 50.54uf ESR= 1.35 ohm( One side bad and one side good)

Here's what one of the new ARS 50/50 caps tested:

Dual 50/50: MAX 1.3 ohm 51.96uf 1.21 ohm 51.32uf 1.09 ohm