ThatMarshallGuy
Active Member
That's what I was afraid of. I was thinking the same thing. That's why I declined the deal.
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Unprofessional mod done?
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That's what I was afraid of. I was thinking the same thing. That's why I declined the deal.
ampmadscientist
Well-Known Member
" I believe it was Aspen Pittman of Groove Tubes that said it was sub par quality EL34's that Marshall was using at the time,..."
Aspen Pittman is nothing more than a glorified salesman.
He is not an expert or authority on vacuum tubes, amps, or any technical matters - at all.
Everything in Pittman's book was copied from other sources.
ampmadscientist
Well-Known Member
"Do any of you know though what damage occurs if you were to take an EL34 powered amp and just plug in 6550's without doing anything other than maybe trying to bias them? and vise versa?"
Yes, it is possible to damage the amp.
It depends on the internal wiring and construction, etc...
Since you have NO pictures of the inside,
it's all just GUESSING.
No accurate determination can be made, based on GUESSING.
Get all the FACTS, get the pictures. Don't assume anything.
*Some Marshall amps were constructed without screen grid resistors. This can be a major problem.
**Some Marshall amps were constructed with screen grid resistors that are incompatible with EL34s.
*** We have no idea if the amp is biased correctly for the tubes that are installed.
I am totally with ampmadscientist on this.
People here have trashed the amp, made huge assumptions based on two photographs without any info.
The OP lacks confidence in a distance sale which is understandable, maybe the price was high.
You can have EL34s, 6550s 6CA7s, HT77s, 6L6s, 6V6s if you want in one of these with minor changes. All you need to do is make sure that the bias is correct (preferably on the cold side for 6550s) and only certain make of 6V6 if plate voltages are high.
As he points out is has a hole (but nothing in it). That is a bargain point to knock the price down of what might be a a beautifully pristine 'killer' amp.
To bin it without more info defies logic
People here have trashed the amp, made huge assumptions based on two photographs without any info.
The OP lacks confidence in a distance sale which is understandable, maybe the price was high.
You can have EL34s, 6550s 6CA7s, HT77s, 6L6s, 6V6s if you want in one of these with minor changes. All you need to do is make sure that the bias is correct (preferably on the cold side for 6550s) and only certain make of 6V6 if plate voltages are high.
As he points out is has a hole (but nothing in it). That is a bargain point to knock the price down of what might be a a beautifully pristine 'killer' amp.
To bin it without more info defies logic
danfrank
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To bin it without more info defies logic
Yes, but you know about amplifiers. This amp will be a good purchase for somebody "in the know" as long as the seller isn't asking an outrageous price for it. There are only a few things that would deter to buying an amp: Tons of holes in the chassis and bad transformers. Even then they are worth purchasing if the price is right.
Look at the work Pleximaster does, which is beautiful.
I think the original poster would do well to buy a "plug and play" amp of his liking. Of course, he will pay a bigger price for such an amp. Or he can do a crash course in tube theory so he will have the knowledge to make better informed decisions on amp purchases.
jack daniels
Well-Known Member
Personalities have absolutely nothing to do with the subject. He ran a vacuum tube business and had millions of tubes to run through his companies hands, I believe this more than qualifies him to make an informed statement. Besides, he had Red Rhodes onboard and Red most assuredly DID know his stuff. As for copying everything in his book from others, as has been said before on the MF "there is nothing new under the sun" regarding vacuum tube technology as applied to guitar amps.
ampmadscientist
Well-Known Member
When Aspen first created Groove Tubes, he told me that all his tubes were "free of microphonics."
from that moment on, he had no credibility.
So what your saying is if you blow one cab your going to go ahead and get another cab and do the same thing? Maybe even a couple more without ever saying to yourself; "Self, maybe we ought to go get this thing looked at before we go and spend money on another cab and blow it too?"
Whoever would continually blow cabs without once thinking about getting their amp checked out after the first one blew should not be using tubes amps. These are basic electronic circuits, and are easy to get repaired. It would be far cheaper to get your amp fixed then to "spend thousands on all the cabs." Just my opinion, YMMV.
There is a lot people who don't change the EL34's 220k grid resistor for the 6550's 150K, or 82k, because they like the sound of it. Leaving the 220k grid resistors in for 6550's lowers the headroom and makes for easier power tube break-up and adds a little more low end.
The AFD100 has the 220k Grid resistors in it for 6550's. Also, Slash's main recording amp has the 220k grid resistors in it with 6550's. And from what I've read about the Marshall's that were shipped to the US with 6550's, a lot of them didn't have the 220k grid resistors changed either for the 6550's.
It will have more of an effect on the tubes life than the amp itself. But you can bias them accordingly so that shouldn't really matter either. So it's not that big of a deal. It's more of a matter of preference.
The AFD100 has the 220k Grid resistors in it for 6550's. Also, Slash's main recording amp has the 220k grid resistors in it with 6550's. And from what I've read about the Marshall's that were shipped to the US with 6550's, a lot of them didn't have the 220k grid resistors changed either for the 6550's.
It will have more of an effect on the tubes life than the amp itself. But you can bias them accordingly so that shouldn't really matter either. So it's not that big of a deal. It's more of a matter of preference.
UL requirements for US were 4 speaker outs at that time. As suggested you need photo's of the board for us.
In addition Mr. Cameron told me that the 1979 2203/1959 Output Transformers are the **** among the guys in the know. Might be worth letting some of us have a look.
Good luck.
You would be surprised what you can and can't do that will make all the difference in the world. Just be careful and know what you are doing before climbing inside the electric circus.
That's a good point and can never be overstated. If you don't know what your doing, don't go inside the amp as there are voltages in there that can kill you. Take it to a tech and let them have a look at it for you. They will tell you what's going on, and if it would be worth it for you to get it or not. If you can't do that, see if you can arrange for someone who knows a little bit about tube amps, Marshall's preferably, and see if they can meet you there.
ThatMarshallGuy
Active Member
Alright so I might have found another head to purchase. There are currently no pictures up so I can't see the condition yet but in the description is says there is an added effects loop. I personally would never use an effects loop but the price is good. Does this affect tone at all?
jack daniels
Well-Known Member
When Aspen first created Groove Tubes, he told me that all his tubes were "free of microphonics."
from that moment on, he had no credibility.
Probably because his people screened them first, which GT use to do a pretty good job of until around the time of the Fender acquisition.
Indeed loops can. It depends on the design.
The Metro Zero loss is a great loop as is Dave Friedmans that is now in the current issue of the Friedman BE 100. There are some good Tube driven loops as well.
Personally, I like loops as they allow studio quality effects and the ability to set a 65% direct and affected signal to blend with the band then a second channel on the rack effect set at 99% direct and affected for solos...totally blows away stupid pedals for a solo boost or the need for a sound engineer who will likely suffer some hearing loss after the second set etc...
Been doing it since the 80's and I am always told...man your solo's just come out so loud like the vocals....dahhhhhh lmfao. Think outside the box.
Sometimes you can just patch it with a short cable if there is no bypass which works well. But there are some garbage loops. Buyer beware.
Good luck, David ♫
