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Old 20th November 2008, 07:24 PM   #1
atmars is offline atmars  United States
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Default 6SL7 5E3 - together at last?

Can I use 6SL7 in the first and or second spots in the 5e3 circuit?

i have a couple of chassis' that have octal and 9 pin sockets and a small pile of 6SL7s. I was originally thinking of having the octal as the second gain/phase inverter stage, but I could have one in the first spot as well. Some have stated that resistor values can be swapped. Just replace the 9 pin socket that takes the 12ax7 and change to an octal socket, use the same values, and you are in business. Some post that using a 6SL7 in either spot is a poor idea. What's the truth?

I don't have a lot of experience in amp building, but I recently completed a 5E3 built in a donor chassis with donor transformers and it sounded great. I'd like to kick it up a notch, but I am not bright enough to do it without some input from the more informed.

Thanks for any guidance on this topic.
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Old 21st November 2008, 07:06 AM   #2
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1st tube is a 12AY7, so it won't work well there without some changes. For the 12AX7 spot, it is probably fine. You might want to tweak some resistors, but it should work OK. These circuits are pretty tolerant.

Fwiw, I used a 6SL7 in a 5F2 type circuit instead of the 12AX7 and it sounds pretty good to me. Friends who are pro players say it sounds good to them, too.
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Old 21st November 2008, 08:38 AM   #3
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The component values for both first and second tube are close to identical!

It will work dropping the 6SL7 right in. Nothing will break.

In guitar amps its all about TONE so there are no rights or wrongs. But they are all OK for 6SL7 in this amp. Listen to the amp and judge!

Also try the phasesplitter/poweramp from 5C3 that in my opinion is really charming.

Personally I prefer EF86 or a cascoded ECC88 at the input and use them in the amps I manufacture and use onstage but thats another story.
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Old 21st November 2008, 11:11 PM   #4
atmars is offline atmars  United States
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Quote:
Also try the phasesplitter/poweramp from 5C3 that in my opinion is really charming.
the 5c3 has one less gain stage, right? How does in compare soundwise to the 5e3?
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Old 22nd November 2008, 01:48 AM   #5
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Wow, memories. In high school I had a 5D3, which was my main
hack-and-listen amp. The 5D3 is the earlier circuit with a 12AY7
and a paraphase splitter 12AX7. The 5C3 used a lower mu tube, I
think a 6SC7? mu of 70, just about where the 6SL7 is.

The change with the 5E3 was reconfiguring the 2nd socket to
a gain stage followed by a concertina splitter. It was done in
the late 50s so probably to suit people who wanted more gain.

I wanted more gain too, being a kid in the 70s, but I ended up
repurposing the mic input to a second stage and adding an AB-763
tone stack, so I had in essence a single AB-763 channel with 6V6
outputs (actually the phase splitter worked off local feedback still).
I still haven't heard a better sounding Fender if I do say so myself...

I think the 6SL7 would probably work fine in both spots, replacing
the 12AY7 in the first socket and the 12AX7 in the second, with about
the same or a little more gain. Nothing would catch fire for sure.

I used to like to go with a 220K instead of the 100K when swapping
a 12AX7 into a 12AY7 socket, maybe somewhere in between for the
6SL7, like 180K for starters but tune by ear for best tone. That's the
plate resistor, I think I left the cathode resistor alone.

What fun! makes me want to tear into my new model "Fender"
"Deluxe" that I bought because it reminded me of the old one.

Cheers,

Michael

PS Your question, soundwise, I think the paraphase 5C3 would
indeed sound different from the concertina 5E3 phase splitter,
but maybe the overall more gain of the 5E3 would make the biggest
difference. I always was partial to the paraphase circuit even though
it uses 2 sections so my fave is still 2 stages into the paraphase...

PPS I do think it's better sounding to use local feedback for the
paraphase. The AB-763 amps like the twin and bandmaster used
a global FB loop that I thnk may be detrimental to tone.
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Old 22nd November 2008, 02:10 PM   #6
atmars is offline atmars  United States
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Wow - great post . Thanks for the info. This probably a topic for a new thread, but do you have any experience with the early Fender "Pro-Amps" running 6l6s? I like to build one but I can't find much info on which is favored by fans.
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Old 22nd November 2008, 09:05 PM   #7
rickl is offline rickl  United States
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my "main" bass amp is a bassman clone (5B6). Cathode bias doesn't have the same power as the bands blackface bassman (aa165?) but killer tone with 2x12 cab. 2 12ax7's and National 6L6GC's.

I just finished a 5E8 (lower power twin) with 6sl7, 6SC7 and NOS TS 5881's (cathode bias). Again, killer tone.

I'd say determine your power requirements and tubes and build something from the fender field guide. You can't go wrong.

rick
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Old 22nd November 2008, 10:02 PM   #8
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There were 3 models of Tweed Pro amps, all with 6L6s and
3 nine-pin sockets.

The early 5D5 was like my old 5D3 but with 6L6s and the third
9-pin used to add another input channel ala the twin.
(paraphase splitter)

The 5E5 is like your 5E3 but with 6L6s and the twin input.
(2 stage concertina splitter)

The 5E5A has the gainstage + CF-driven tone stack of the 5E8 twin
plus the 2 stage concertina splitter, but uses only one tube for input.
Basically the 5E8 with one input tube. Most gain of the 3 I'd expect.

Now I have a lot of ideas for hacking my Hot Rod Deluxe...

Cheers,

Michael

PS as you see by now Fender did a lot of circuit/stage mix-n-match
and you can do more of the same to build your own flavor amps.
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Old 23rd November 2008, 12:34 AM   #9
Trout is offline Trout  United States
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Quote:
Originally posted by Michael Koster

The 5E5 is like your 5E3 but with 6L6s and the twin input.
(2 stage concertina splitter)


Does the 5E5 still get the volume control interactions as the 5E3?


5D5 Wide Panel

5E5 Narrow Panel

5E5-A Narrow Panel
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Old 23rd November 2008, 05:34 AM   #10
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Quote:
Originally posted by Trout



Does the 5E5 still get the volume control interactions as the 5E3?


5D5 Wide Panel

5E5 Narrow Panel

5E5-A Narrow Panel

Good point. The 5E5 has 2 input tubes, 4 channels, like the twin,
but the pairs are wired like the 5E3, not like the twin. The 5E5A
is wired like the twin. (The 5E5A schematic is missing something...
compare with the twin...)

It has to do with the tone stack. Seems the 5E3 and 5E5 volume
control wiring is to facilitate the tone control. The tone control on
these works differently on the mic channel; I think when you crank
the treble it only affects the instrument inputs. Nice if you are
actually using the mic input and playing Ventures or Surfaris
covers. But the volume controls do fight each other a little.

The 5E5A and twin tone stack is after the mix, so it affects both
mic and instrument equally, but the instrument has a brighter
tone overall. Volume controls are independent.

Michael
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