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Dirk
Platinum Member
Netherlands
1309 Posts |
 Posted - 05/01/2008 : 13:18:10
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Okay, sound samples first, pictures later.
I had the same settings on both amps, using my Custom les Paul guitar with Alnico II pro pickups.
Now these samples don't do justice to both amps, cause the good amp sounds better in real and the dodgy amp sounds a little worse in real.
I just used a low budget mic through an old Tascam 4-track used as mic pre. Notice how it sounds like the speaker is on the verge of blowing up on the bad amp, but it's not, it sounds exactly as bad through my good vintage 30 speaker.
So here's the good amp:
http://members.chello.nl/r.hofman9/goodamp.mp3
And here's the bad amp:
http://members.chello.nl/r.hofman9/dodgyamp.mp3 |
Edited by - Dirk on 05/01/2008 15:13:06 |
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Dirk
Platinum Member
Netherlands
1309 Posts |
Posted - 05/01/2008 : 14:00:32
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Picture time:
The wall of sound:
Both amps opened up on the floor:
The new amp:
The bad amp:
As it turns out, the dodgy amp as Franzoni called it  (I'm gonna call it "Dodge" from now on) is an '83 model.
The new amp is from '84 and apparantly underwent some major design update, most notably the channel switching chip near the input.
I wasn't aware that those changes allready took place in '84, I was under the impression they took place in '88 cause I read something about a major upgrade in '88.
Besides, my brothers '88 jcm800 2210 head guts look pretty much like my '84 guts.
So now it's going to be a little harder to fix the old amp, since I have nothing to compare it with, those circuits are quite different.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/01/2008 : 17:21:54
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Hi Dirk
Thanks for the great pictures,
Nice Mini-Stack
You might be able to get the Schematics from Schematics Heaven.
I found the one for my Marshall 8008 rack head,
over on the Marshall site itself.
Might be worth your time to go over & take a look around.
Regards Dr. Bob |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 05/02/2008 : 11:43:13
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Very strange... ...a couple of bass players i know use active DI's with EQ like the sansamp or MXR and as an experiment i showed them how to use the return input on their effects loop to bypass the preamp section on their amps and it worked no problem.... as far as i remember the effects loops on the marshalls are series ones,so 'dodge' might have a problem there and it could be whats causing the poor sound quality......did you try the guitar into the DD3 and then into the return input of the effects loop on the 'good' amp or do both amps not work when anything is plugged directly into the effects loop return....??......still think it's a sweet setup and if you could get 'dodge' up and running it would sound great even if you just used the clean channel and used pedals for dist/drive.... |
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Dirk
Platinum Member
Netherlands
1309 Posts |
Posted - 05/02/2008 : 16:24:58
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Well, my brother had a look at it.
He removed some of the mods, you know all the added resistors in the pic.
The fx return turned back to normal, he could play with a signal from his 2210's send into my dodgy amp return and it works perfectly.
The volume issue has been solved to a degree, it's a lot louder now.
It's still sounds a little woofy with the gain above 6.5 on the overdrive channel and we can't get that reverb to work.
It's probably the preamp tubes being too old, we replaced some of 'em with some spares we had lying around and it made the amp sound considerably better.
I haven't decided what to do with it, should I buy new tubes for it or just sell it off as-is?
I allready found a nice replacement for it, which has the channel switching update and sounds really great.
Since I'm really a bassplayer who happens to play a little guitar as well, I don't have the need for 2 amps, nor the room to store it and I don't intend to start a Marshall amps museum
I'm gonna hold on to it for a while, and most likely sell it later. |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 05/02/2008 : 21:41:12
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| If you don't mind me asking..what sort of price are those marshall combos going for in the Netherlands.....and whats the clean channel like.....??... |
Edited by - FRANZONI on 05/02/2008 21:41:37 |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/03/2008 : 04:14:23
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Hi Dirk
It's good to hear that you & your brother have almost resolved the problem with the send return jacks & the unofficial mods.
As for the Reverb tank:
Look at the wires commenting the RCA sockets on the actual tank itself.
I have found that some of these break off or have been poorly soldered.
Sometimes the RCA socket gets damaged, or shorts out the inner to the metal ground of the tank.
Check the RCA leads that connect into & out of the tank, for open or shorts.
Check to see if the spring-s have become disconnected from the little mounts that feed the send & pickup coils-transformers inside the tank.
If it's a true tube drive, maybe the little transformer that feeds the tank has something wrong with it.
And of course, check the reverb driver valve, it's normally a 12AT7 or a 12AY7.
Good luck, nice looking amps.
Regards Dr. Bob
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Dirk
Platinum Member
Netherlands
1309 Posts |
Posted - 05/03/2008 : 11:04:02
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quote:
Originally posted by FRANZONI
If you don't mind me asking..what sort of price are those marshall combos going for in the Netherlands.....and whats the clean channel like.....??...
I bought the first one for 470 euros including a nice flightcase and the second one for 425.
Heads on the other hand are skyrocketing, my brother payed 650 for his 2210, but I've seen prices of around 800 and upwards.
Not to mention the Jubilee series, those prices are even higher and still in full demand.
Dr. Bob: I replaced the tank with another one from a Park combo and it still didn't work, so I hooked up my tank to the Park and it worked just fine, so there's nothing wrong with my tank but something else. We also replaced driver tubes and measured the wires OK, but still no luck. |
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New amp for me
