Metropoulos Forum

joey wrote:

mensur wrote:Joey is right about pussy pot
Here's the complete schematic with passive loop, if there's something to fix in the power amp please tell:
http://img543.imageshack.us/img543/449/chuppacabra.png

Very close Mensur! thats 95% - 98% of it. the other 2-5% wont make a huge amount of a difference. you missed the 100K gridstopper though between the first and second stage.

Here's complete:
http://img847.imageshack.us/img847/6138/chupacabra.png
Joey is the input capacitor 22nF(C32) in my scheme OK? Also, is the order of the components OK(68K,22n,1M to gnd, or it needs to be 68K,1M to gnd, 22n)? PI caps are supposed to be 22nF, so I changed them too.

from the pics seems there is a cap from input grid to ground, no? allso what about the gooped black thing?

nico21 wrote:from the pics seems there is a cap from input grid to ground, no? allso what about the gooped black thing?

No, the black gooped thing is a cap, it prevails electric shocks if tube fails.Nobody want to play 350VDC guitar
Here's another gutshot, which is the same as my input, I'm only asking for the right value of cap and grid stopper.
http://img233.imageshack.us/img233/4848/chupacabra.png

i would say what you labelled as the 1meg res looks more like a cap,
The 1meg res is probably right at the input jack,
....just a guess really not sure

yuanyelss wrote:Do not think that Mark was ripped off too bad to be honest, in fact, he may even have the last laugh. Treasures of the circuit is a one-time use, it is a tear over it, one of the bad sounding...

Amp sounds great to me.

FourT6and2 wrote:

yuanyelss wrote:Do not think that Mark was ripped off too bad to be honest, in fact, he may even have the last laugh. Treasures of the circuit is a one-time use, it is a tear over it, one of the bad sounding...

Amp sounds great to me.

I think you just quoted and responded to a spam bot. It looked like it took statements in this whole thread and scrambled them to make itself look like a real user

joey wrote:

mensur wrote:Joey is right about pussy pot
Here's the complete schematic with passive loop, if there's something to fix in the power amp please tell:
http://img543.imageshack.us/img543/449/chuppacabra.png

Very close Mensur! thats 95% - 98% of it. the other 2-5% wont make a huge amount of a difference. you missed the 100K gridstopper though between the first and second stage.

Hi Joey
Is it possible to have a copy of this Chupacabra latest schematic?
When I clic on your PNG file, I get a error message.

Thanks a lot to share this with us

Stephane

I'd also like the schem, thanks

Here you guys go:

http://dl.dropbox.com/u/7561678/Chupaca ... ematic.png" onclick="window.open(this.href);return false;

Colossal wrote:Here you guys go:

http://dl.dropbox.com/u/7561678/Chupaca ... ematic.png" onclick="window.open(this.href);return false;

Thanks a lot Colosal

Question, do you know what Choke value is on?

Regards
Stephane

Stephand wrote:Question, do you know what Choke value is on?

Regards
Stephane

No, sorry Stephane, I don't know the actual chokevalue. I did build this very amp (with a few very minor changes) and I used a 10H 200mA choke. The amp sounded very good. I changed the V1a load resistor to 330k (instead of 430k as shown) and used 0.1uF output coupling caps which I believe is what they should be (based on a gut shot of a Chupa). 0.022uF as shown on the schematic is a typo.

Colossal wrote:

Stephand wrote:Question, do you know what Choke value is on?

Regards
Stephane

No, sorry Stephane, I don't know the actual chokevalue. I did build this very amp (with a few very minor changes) and I used a 10H 200mA choke. The amp sounded very good. I changed the V1a load resistor to 330k (instead of 430k as shown) and used 0.1uF output coupling caps which I believe is what they should be (based on a gut shot of a Chupa). 0.022uF as shown on the schematic is a typo.

Thanks for your quick answer
The 0.1uF output coupling make sense since it look to be the Norm for this type of mod.
Did you try the 2.7K/0.68 on the cathode on V1a/b and V2a? I saw other Shem with this value
Did you also put the Diode?

Thanks
Stephane

Stephand wrote: Thanks for your quick answer
The 0.1uF output coupling make sense since it look to be the Norm for this type of mod.
Did you try the 2.7K/0.68 on the cathode on V1a/b and V2a? I saw other Shem with this value
Did you also put the Diode?

Thanks
Stephane

Stephane,

I used 0.1uF for the output coupling caps. Nice fat, tight low end. No, I did not use 2.7k/0.68uF on any stage --- 820R/0.68uF straight across. I made the first stage bypassable via a relay so it would be either 820->820 or 820->820>820. With just two stages, you get the full plexi vibe. Switch in the added gain stage in front (remember I used 330k instead of 430k on V1a) and it gets more modern sounding. There was the usual slight jump in gain hiss but overall the amp was remarkably quiet. I used the Larry Grounding scheme.

Yes, I did add the diode clipping stages just after the cathode follower. The 12V zeners give a killer sound, very modern but they do suck out some overall volume. I think I used either 16 or 20V zeners for the other side. The diode clipping switch was a 3-way on-off-on and the middle position was "off", no diode clipping. The 16/20V zeners give some nice added crunch for a more 80's style sound. I really liked the amp with both bright switches engaged (470pF) and the 12V zeners in. Cranked up with a 7-string and the tone was pretty amazing. I actually used a 5k8 primary OT and set it up to be switchable between EL34s and 6L6s (switchable bias circuit...client request) so it was not going to be "pure" Plexi sounding with that primary. Sounded killer though, more modern in a way, very tight and warm. Not at all trebly. I used polypropylene IC coupling caps throughout and Sozos in the tone stack. Very clear sounding with great note-to-note separation. Of note, if you turned down gain one and two and the preamp master, with the bright switches engaged, the amp gave an amazing chimey clean tone...really nice sounding. But the amp was for distortion

Hope this helps.

Colossal wrote:

Stephand wrote: Thanks for your quick answer
The 0.1uF output coupling make sense since it look to be the Norm for this type of mod.
Did you try the 2.7K/0.68 on the cathode on V1a/b and V2a? I saw other Shem with this value
Did you also put the Diode?

Thanks
Stephane

Stephane,

I used 0.1uF for the output coupling caps. Nice fat, tight low end. No, I did not use 2.7k/0.68uF on any stage --- 820R/0.68uF straight across. I made the first stage bypassable via a relay so it would be either 820->820 or 820->820>820. With just two stages, you get the full plexi vibe. Switch in the added gain stage in front (remember I used 330k instead of 430k on V1a) and it gets more modern sounding. There was the usual slight jump in gain hiss but overall the amp was remarkably quiet. I used the Larry Grounding scheme.

Yes, I did add the diode clipping stages just after the cathode follower. The 12V zeners give a killer sound, very modern but they do suck out some overall volume. I think I used either 16 or 20V zeners for the other side. The diode clipping switch was a 3-way on-off-on and the middle position was "off", no diode clipping. The 16/20V zeners give some nice added crunch for a more 80's style sound. I really liked the amp with both bright switches engaged (470pF) and the 12V zeners in. Cranked up with a 7-string and the tone was pretty amazing. I actually used a 5k8 primary OT and set it up to be switchable between EL34s and 6L6s (switchable bias circuit...client request) so it was not going to be "pure" Plexi sounding with that primary. Sounded killer though, more modern in a way, very tight and warm. Not at all trebly. I used polypropylene IC coupling caps throughout and Sozos in the tone stack. Very clear sounding with great note-to-note separation. Of note, if you turned down gain one and two and the preamp master, with the bright switches engaged, the amp gave an amazing chimey clean tone...really nice sounding. But the amp was for distortion

Hope this helps.

oh Yes this help thanks, thanks to share your esperience.
About the Diode, are you using normal Zen like 4747?

Stephane

Oh Forgot
Colossal, is Larry's Grounding Schem make a huge difference?

Should I change my original Marshal one?

Stephane