Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
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Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
I just got one of these very cheap.
Can anyone explain the schematic to me ? It looks weird, what are the extra tube stages after the PI for ?
Schematic here:
TIA
Can anyone explain the schematic to me ? It looks weird, what are the extra tube stages after the PI for ?
Schematic here:
TIA
Last edited by MacGaden on Fri Aug 28, 2009 1:22 am, edited 1 time in total.
MacG.
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Re: Marshall 9005 Poweramp ?
Good question, not sure I have seen that before either.
Do you have any pictures of the amp you could share?
Do you have any pictures of the amp you could share?
Tom
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Re: Marshall 9005 Poweramp ?
Not yet, but I´ll take it apart in the weekend..Structo wrote:Good question, not sure I have seen that before either.
Do you have any pictures of the amp you could share?
Those extra stages after the PI looks very strange. What are they for ?
MacG.
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Re: Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
That extra 12AX7 is extra driver tube that deliver more current to amp when switched in triode mod.MacGaden wrote:I just got one of these very cheap.
Can anyone explain the schematic to me ? It looks weird, what are the extra tube stages after the PI for ?
Schematic here:
TIA
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Re: Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
Interesting.. Tell me some more. How does that work ?mensur wrote:That extra 12AX7 is extra driver tube that deliver more current to amp when switched in triode mod.MacGaden wrote:I just got one of these very cheap.
Can anyone explain the schematic to me ? It looks weird, what are the extra tube stages after the PI for ?
Schematic here:
TIA
MacG.
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My son Adam at 3 years old. Best advice I ever got..
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Re: Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
Local FB around those stages gives them a low output impedance to easier drive what follows, also a wider/flatter frequency response along with consistent performance less dependent on the particular 12AX7 used.
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Re: Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
Thanks, i haven´t had a chance to hear it yet, but: It should sound cleaner that a direct power amp in a 50 wat Marshall ?SDM wrote:Local FB around those stages gives them a low output impedance to easier drive what follows, also a wider/flatter frequency response along with consistent performance less dependent on the particular 12AX7 used.
That might be OK, as I may use it for a W/D/W setup. If it doesn´t I could always turn it into something else, PTP and Sozo´s..
MacG.
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Re: Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
Its good advice to use ECC81/82 instead of ECC83 because they will deliver more current to the output.It's not going to cleaner sounding, it will have more damping, better dynamic's, smoother and richer harmonics hence it's low impedance driver.
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Re: Paging Larry/SDM/Techs...Marshall 9005 Poweramp circuit ?
I thought that they might be there to minimize the distortion. PR1 "sets balance" which I assumed was to help make the pushing and the pulling of the power stage equal on both sides. It might help with increasing the max power before distortion so both power tubes start to clip at the same time. I think trying to do this in a normal phase inverter will cause more problems than it would solve. It would be hard to do it without creating frequency response or biasing issues.