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Originally posted by Enzo
I have a sign in my shop that says, "Never think up reasons not to check something."
I don't think I can comment on the sound of the amp. It sounded quite obvious to me that there is either effect pedal and/or special effect in the recording. Once you have that, you really are not listening to the amp.
Case in point, I heard a lot of fantastic demo of the JCM800 2204. But when I look at the schematic, I don't see how it can have enough gain at the preamp to get any reasonable distortion. I since build the whole preamp section into my Bassman platform. Sure enough, I cannot get any meaningful OD unless I crank the whole thing way up to get the power amp distortion.
I tested quite a few amps including Mesa, Peavey, Fender, Marshall, PRS and some I forgot the names, if there is no pedal in front of it, they sound nothing like the demos.
Maybe, it's better to say whether the amp can take pedal well or not!!!
JCM800 2204. But when I look at the schematic, I don't see how it can have enough gain at the preamp to get any reasonable distortion.
You don´t?
Please post the preamp schematic you built.
Don´t link to Marshall site and say "this one", draw what you actually built.
Some picture would also help.
I since build the whole preamp section into my Bassman platform. Sure enough, I cannot get any meaningful OD unless I crank the whole thing way up to get the power amp distortion.
Amazing.
Which input are you using, normal or high gain?
I'm with Alan on the "where's the pedal?" Not for the gain, but where's the trem & flanger/phase effect coming from? I'd know a lot more of what the amp was capable of in a non-band setting. All I mostly saw was guitar neck & player's head. Like the song, nothing bad to say about the amp, but definitely too slick for me to make an opinion on. Strip it down to guitar-cord-amp, all in plain sight, then we're talking!
Justin
"Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
"Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
"All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -
You don´t?
Please post the preamp schematic you built.
Don´t link to Marshall site and say "this one", draw what you actually built.
Some picture would also help.
Amazing.
Which input are you using, normal or high gain?
I build the 3 stages exactly like the 2204. I even make sure the voltage at all points are reasonable close to the schematic also. That is like driving the HI input. It is exactly the circuit, every single value of the components are the same. I don't have a schematic drawn as it's just the exact copy.
If you look at the second stage with cathode resistor of 10K without bypass cap. That makes the gain of the stage lower. If I bypass the 10K, at least I get more OD. I use new JJ 12AX7 also, so tubes should not be a problem.
I've built two of the JCM800 2204 cascade amps, one with EL34s w/marshall type Iron, and one with 6L6s w/Fender type iron.
They both had tons of drive.
Make sure the cascade low and high jacks are wired correctly.
On High you should have 1b tied to 1a through the jacks.
Another key factor to gain at low volumes, is the additional PPIMV.
I wouldn't want a 2204 without both pre and post MVs.
I built both into the front panel on both of my amps.
T
Alan,
I agree with the others that you should have been able to get lots of overdrive type distortion out of the circuit you intended to build. I remember thinking when you originally posted the results that something must have been wrong because the cascaded version of the Marshal pre-amp in the 2204 should have lots & lots of gain.
Tom
I've built two of the JCM800 2204 cascade amps, one with EL34s w/marshall type Iron, and one with 6L6s w/Fender type iron.
They both had tons of drive.
Make sure the cascade low and high jacks are wired correctly.
On High you should have 1b tied to 1a through the jacks.
Another key factor to gain at low volumes, is the additional PPIMV.
I wouldn't want a 2204 without both pre and post MVs.
I built both into the front panel on both of my amps.
T
I wired to totally bypass the low gain jack. I just drew out the schematic and attached here. It is just the 2204 driving the Hi input.
BTW, I use Strat with lower output pups, not the high output HB guitar. That can make a day and night difference.
I wired to totally bypass the low gain jack. I just drew out the schematic and attached here...
Alan,
That circuit you posted is two gain stages and a CF then you show the output of the tone stack driving the PI.
That is not the Hi Gain Marshall preamp the other guys were talking about. The Marshall Hi Gain setup includes an additional gain stage.
Tom
Thanks.
Don't know about your guitar but the schematic you posted sings all night long with humbuckers and provides more than a nice crunch with any normal Strat.
You didn't write the 2nd triode plate resistor value but I assume it's 100K.
That said, try the PPIMV suggested by Big Tee, you'll like it.
"Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
"Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
"All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -
Thanks.
Don't know about your guitar but the schematic you posted sings all night long with humbuckers and provides more than a nice crunch with any normal Strat.
You didn't write the 2nd triode plate resistor value but I assume it's 100K.
That said, try the PPIMV suggested by Big Tee, you'll like it.
@Tom: Alan shows 3 gain stages and a CF
Yes, it has crunch, just not rich OD. Yes, I'll experiment on that.
Opps. Now I see the third stage. So, Alan, it remains a mystery to me why you didn't get lots of gain to spare out of that circuit.
Tom
Maybe is just different interpretation of "OD" and high gain. I never feel there's enough gain with 3 stages. I use 1.5K bypassed by 0.22uF at the cathode of the second stage and 1uF bypass the 820 cathode resistor of the third stage to get enough OD for my taste.
Actually that was the reason I actually build the 2204 front end to hear it with my own ears how people keep saying it's the standard of high gain amp by which other amps are being judged.
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