So I found this old Jeff Seal post on 2205/2210's... 800 info

J Moose

New member
I can't specifically remember which or where it was... found it a couple three weeks ago. He was talking about the differences in the preamp section of the 2205 & 2210... that aside from minor tweaks the only major revision was done in '86 or '87 and to find out which version you have... pull V2. Either one channel stops working (boost!) or both stop on the later revisions... Most/all of the changes addressed the known "channel bleeding" issues of normal being audible even while boost is selected...

Well...

I have an '84 2205, so it should be first version. I've had it modified but that was all contained to the boost channel, removed the diode clipping & made some changes to the tone stack, EQ voicings... other then that the amp is bone stock. Always defaults to the boost channel, you can't even get 'normal' w/o a footswitch which I haven't had for eons... I always got around the channel bleed thing by using the 2205 as a single channel amp & turning all the 'normal' channel knobs to "off" position. The 800 has always sounded "good" too... not my favorite amp but I didn't buy it for me really!

So late last night, for the halibut I decided to pull V2... just so I could hear the boost channel "not work" and confirm which revision of the preamp circuit was in my amp...

Well... I was shocked...

astounded...

totally flummoxed...

Blown away!!!

Took the amp out of standby and the boost channel kept going...

But not only did it keep going... but the amp sounded A MILLION TIMES better too!!! Remove a tube and get MORE tone??? How's that work?!?

With V2 removed the normal channel is deactivated entirely... no more channel bleeding. Even though I had the knobs set to "off" apparently there was still quite an effect on the boost!!!

Amp got louder... clearer... bigger... smoother... sustained longer...

Not a subtle difference!!! Amazing... totally amazing...

I kept replacing & pulling V2 just to confirm that yes... I was hearing & feeling an audible difference and there was! Even more so, the differences between tubes in V1 are MUCH more pronoucned! Put in an Ei or JJ, Amperx, Brimar etc. and the differences in tone and gain are just way more obvious without V2 in the way!!!

Completely shocking...
 
Re: So I found this old Jeff Seal post on 2205/2210's... 800 info

Has it had a cap job done on the power supply caps in recent years?
It sounds like with a full compliment of valves you're not getting enough power!
Or/Is this an issue of the normal channel inter-acting with the boost channel?beyond the issue quoted
"channel bleeding" issues
.
 
Re: So I found this old Jeff Seal post on 2205/2210's... 800 info

Clean channel interacting w/boost channel. Apparently totally "normal" for those old 2205/2210's... at least the first versions of the preamp circuit.

The filter caps ARE kinda old, I've owned the amp for 10 years and haven't replaced them... so new caps are in route but that has nothing to do with the channel cross-talk.
 
Re: So I found this old Jeff Seal post on 2205/2210's... 800 info

The filter caps ARE kinda old, I've owned the amp for 10 years and haven't replaced them... so new caps are in route but that has nothing to do with the channel cross-talk.
beyond the issue quoted?

What i was suggesting is the power draw at plate voltage ,with a full compliment of tubes; was not remaining high enough.hence the performance increase ,minus one tube.It was just a thought from the trouble shooting side of my brain/work.:cool2:
 
Re: So I found this old Jeff Seal post on 2205/2210's... 800 info

Nah. The channel bleed is more about grounding & how the circuit was laid out on the board...
 
Re: So I found this old Jeff Seal post on 2205/2210's... 800 info

I've heard that bassman amps have the same thing. If you pull one tube it will boost the other channel. It's apparent'y a matter of the voltage being split among the pre tubes I think. It's been a while since I read that and I can't remember where I read it at, so I could be totally wrong.
 
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