UltraHookedOnPhonix wrote:These are the values I see (along with some educated guesses):
Another observation: the feedback resistor looks to be series connected 3K3+270R, for a total resistance of 3.57K.
Also, I'm guessing but the treble cap is probably 500pF and the snubbers in the 270pF range.
Thanks for this UHOP! So this looks to be a low plate classic? I was thinking the FB resistor was 3K3 and the tail was 270r, with adj set accent/pres 500k trimmer?
I can see what looks like the 220K//500p grid on 2nd stage, but I can't see the 180K stopper. Surely it's there though.
Any more pics redshark?
Tonestack has no caps on basspot but a resistor, so I'm guessing 330p treble cap for the classic stack.
Any other observations?
Smokebreak wrote:Well thanks for the pics and demo then, redshark!
UltraHookedOnPhonix wrote:These are the values I see (along with some educated guesses):
Another observation: the feedback resistor looks to be series connected 3K3+270R, for a total resistance of 3.57K.
Also, I'm guessing but the treble cap is probably 500pF and the snubbers in the 270pF range.
Thanks for this UHOP! So this looks to be a low plate classic? I was thinking the FB resistor was 3K3 and the tail was 270r, with adj set accent/pres 500k trimmer?
I can see what looks like the 220K//500p grid on 2nd stage, but I can't see the 180K stopper. Surely it's there though.
Any more pics redshark?
Tonestack has no caps on basspot but a resistor, so I'm guessing 330p treble cap for the classic stack.
Any other observations?
Yeah, that makes much more sense. Almost the same feedback ratio as 4K7/390R. Could be wrong but it looks like the accent switch is on-on with one side switching to ground and the other to the 500R pot wired as a VR. I think the attached schem is what you're driving at, although it's drawn without the switch. Need more pics to verify...
BTW, I'm sure you meant 500 Ohms and not 500 KOhms right?
I also think the 220K/500p and 180K stopper are hiding under the board.
And yes...it does look like a low plate classic.
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Ah yes I meant 500r.
Ok I see what you are thinking regarding the way the pot is wired. I was thinking it was in parallel with the 270r, but i guess that would affect the tail value too much.
The only other variation from say 124 looks to be the 10n coupler after the 2nd stage.
redshark wrote:I have lots of pics of this amp. What would you like to see?
I just don't want to post all that I have, it's repetitive. But let me know anything that you want a close up.
Thanks redshark, you may be surprised to hear that most of us here would not find a multitude of pics "repetitive"
So I would encourage you to post everything you have.
I would like to see the pots and switches on the front panel, and a view from between the preamp boards and the tube sockets, just to verify some of the grids. I'm also interested in this accent setup, and the value of the cap, as well. Thanks!
redshark wrote:I have lots of pics of this amp. What would you like to see?
I just don't want to post all that I have, it's repetitive. But let me know anything that you want a close up.
Thanks redshark, you may be surprised to hear that most of us here would not find a multitude of pics "repetitive"
So I would encourage you to post everything you have.
I would like to see the pots and switches on the front panel, and a view from between the preamp boards and the tube sockets, just to verify some of the grids. I'm also interested in this accent setup, and the value of the cap, as well. Thanks!
I defiantly agree with that. Would not mind at all myself as I'm sure with most folks here.Thanks for all pics you've posted ,and for all you may share in the future. Chad
I just tried that and it works well. The whole range across the 500r is useful, especially with buckers. In addition to the presence boost, and of course depending where th pot is set, it considerably decreases the NFB so thewhole amp gets a little more agressive .FWIW I'm partial to the earlier low gain variants, but I put this one in a 50W cathode biased mule last night and it flat out rocks. Not too much gain either. I'm trying to figure out how Derek got so much gain out of it at those moderate settings. All I can think is that the drive pot is linear and the trimmer is set way high.
Edit : tried the .1 cap and I couldnt hear a difference with it in or out of the circuit. I was also wrong about the NFB reduction. Not sure what I was thinking
Last edited by Smokebreak on Sun Jan 03, 2016 11:44 pm, edited 1 time in total.
The 2nd gen amps with the Accent switch are either on or off.
Maybe players felt that there was too much of an extreme, so when the 3rd gen amps came out with the Accent switch maybe they have this adjustable Accent circuit. Some of these amps also have the accent pot mod? Eg:- #94.
4th gen amps now have the Presence on the front.
The 2nd gen amps with the Accent switch are either on or off.
Maybe players felt that there was too much of an extreme, so when the 3rd gen amps came out with the Accent switch maybe they have this adjustable Accent circuit. Some of these amps also have the accent pot mod? Eg:- #94.
4th gen amps now have the Presence on the front.
Just a thought.
Aaron
Most 2nd generation ODS amps without later mods: ACCENT on/off without trimmer.
Most 3nd generation ODS amps without later mods: ACCENT on/off without trimmer.
In a transition generation ODS amp with an ACCENT on/off switch on the front a trimmer for this ACCENT switch is rather usual. See the attached picture of this trimmer in ODS 100W #0093 (built for Carlos Rios, now used by Ben Harper): http://www.thegearpage.net/board/index. ... -b.473990/
The 2nd gen amps with the Accent switch are either on or off.
Maybe players felt that there was too much of an extreme, so when the 3rd gen amps came out with the Accent switch maybe they have this adjustable Accent circuit. Some of these amps also have the accent pot mod? Eg:- #94.
4th gen amps now have the Presence on the front.
