SSS a Hartman Manning Affair

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dreric
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Re: SSS a Hartman Manning Affair

Post by dreric »

martin manning wrote: Mon Nov 06, 2017 6:21 am
Interesting thought about the Varitone circuit. HAD borrowed from others just like everyone else so there might be something to that. Like you I find it hard to believe he would keep the inductor in the circuit if it doesn't do anything, but the response of the filter as shown looks like it will be very effective.

I see you have both the bias trimmer on the filter board and the full-size bias trim pot mounted on the chassis. You don't need both, so maybe you could remove the trimmer and run three wires from the bias pot lugs to the trimmer eyelets?
Martin,

As always I appreciate your response and insight. To clarify, are you saying that the response of the filter WITH the inductor looks effective or the response with your modifications?
If I was to use the inductor as in the Gibson schematic it it would be from the 3n cap and the 100K resistor to ground, correct?

As for the bias timmer, I had installed the pot on the chassis before I did your modification. I think that I will run wires so I can bias without removing the chassis. Actually, now that I think about it maybe I should install a second bias pot. Most of my 6550 are unmatched, then I could bias them individually.
Eric
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
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martin manning
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Re: SSS a Hartman Manning Affair

Post by martin manning »

The response of the tweaked filter without the inductor looks good to me. Pretty flat with both switches at their mid position (with a small mid scoop), then +/- 6dB or so on each end using the other switch positions.

Adding a second bias pot would require some more extensive rework. I'd hook up the chassis mounted pot for external access and call it good.
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dreric
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Re: SSS a Hartman Manning Affair

Post by dreric »

Martin,

Is there a typo in the resistor values? You have 221k twice.
E
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Eric
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martin manning
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Re: SSS a Hartman Manning Affair

Post by martin manning »

dreric wrote: Sat Nov 11, 2017 5:08 amIs there a typo in the resistor values? You have 221k twice.
No, 221k twice is correct.
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dreric
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Re: SSS a Hartman Manning Affair

Post by dreric »

Thought I would share a little progress on the filter construction and the completed FET board.

Waiting on a Mouser order for the one resistor I didn't have (160K) to execute Martin's revamped filter circuit.
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Eric
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dreric
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Re: SSS a Hartman Manning Affair

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Here's the "medusa board"
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Re: SSS a Hartman Manning Affair

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Main board in place. Power and the leads from the board onto sockets wired. This amp has a lot of stuff hanging off the sockets so I'm working from the bottom up.

I need suggestions on how to wire the 6550's, same a a 6L6? I've never worked with them before.
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Eric
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martin manning
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Re: SSS a Hartman Manning Affair

Post by martin manning »

Good progress!
dreric wrote: Wed Dec 06, 2017 6:06 amI need suggestions on how to wire the 6550's, same a a 6L6?
Yes, they have the same pinouts, so put grid stoppers and screen resistors on the socket pins in the same way.
dreric wrote: Wed Dec 06, 2017 6:06 amSo after much deliberation I've decided to run the amp in standard linear wiring rather than the ultra-liner. The main reason is simply that no one, other than Sunn, has made a good sounding guitar amp with the ultra linear design. I can always change it up later if there are complications.
I'd want to hear it both ways, and standard p-p might be problematic for the reasons I described above. Don't forget you do have the Sunn OT, maybe that's where the magic is? ;^)
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dreric
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Re: SSS a Hartman Manning Affair

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I've re-read the whole thread and I decided to go ahead and wire the OT ultralinear as it's designed. I am going for a different sound with this amp and incorporating the re-vamped filters and adding a presence pot...........so what the heck.

Here's some progress on the filters. I'm concerned about my wiring on these; comparing Martin's mods to the layout to the schematic is difficult.

Got all the grounds hooked up and pretty much buttoned up the front of the amp. I couldn't help myself. I kept the inductor; I send so long looking for one. I did wire so I can pop it out easily and plan to A/B with plian wire once the amp is up.
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Eric
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dreric
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Re: SSS a Hartman Manning Affair

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close up on the filter construction
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Eric
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martin manning
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Re: SSS a Hartman Manning Affair

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Almost there! When is the smoke test?
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dreric
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Re: SSS a Hartman Manning Affair

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got a ways to go..............
Eric
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stephenl
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Re: SSS a Hartman Manning Affair

Post by stephenl »

You could add in a couple of small relays and make it switchable between UL and Pentode. I did this on one build but I always leave it in Pentode. To me, UL sounds kinda lifeless.
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didit
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Re: SSS a Hartman Manning Affair

Post by didit »

stephenl wrote: Mon Dec 11, 2017 11:17 pm You could add in a couple of small relays and make it switchable between UL and Pentode. I did this on one build but I always leave it in Pentode. To me, UL sounds kinda lifeless.
Did your setup disconnect the power amp NFB when UL was connected? Leaving both is definitely deadening.

Best .. Ian
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dreric
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Re: SSS a Hartman Manning Affair

Post by dreric »

9 pins tubes all wired, except for heaters

There's a lot of stuff hanging off the tubes in this build.
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Eric
1949 Zenith, Zenith Toggle Recoil, Zenith 55 & 440
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