Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Willabe on March 05, 2016, 03:25:46 pm
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I have my shop cleaned up so I can find things, will post pics soon, but I have a few things I want to try now that I've been thinking about for a long time.
I have 5 questions below;
I want to try adding a set of 1/4" jacks as insertion points (1/2/3 in drawing below) for a delay pedal and/or a stereo flanger/chorus pedal.
I want to delay the dry signal ~10 to maybe 40mS and mix it back with the modulated signal. And vise-versa, delay the wet signal and mix it back with the dry signal.
Also, I want to try a flanger/chorus pedal on the Warbler dry signal, with JUST/100% pedals wet signal, which is just the time modulated signal, and mix it back in with the Warblers modulated/pitch shift signal.
1.Depending on the pedal I might need signal trim pots before/after the pedal like in #1?
And, because I saw the Sigmund Doppler Vibe pedal/Doppler amp combo ( link; http://el34world.com/Forum/index.php?topic=19990.msg209086#msg209086 (http://el34world.com/Forum/index.php?topic=19990.msg209086#msg209086)) I want to try and make the Warblers modulated/pitch shift signal asymmetrical. (#4 in drawing below.) I'd like to hear how that might sound.
2. Would doing that put stress on the SR coil and burn it up?
3. If no, would I need to use 3 pots, 1 after each pith shift stage?
4. Do you think adding a mix pot where I put it (#4) would do it?
5. If yes or no, any other way to knock it out of balance, make it asymmetrical?
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... And, because I saw the Sigmund Doppler Vibe pedal/Doppler amp combo ( link; http://el34world.com/Forum/index.php?topic=19990.msg209086#msg209086 (http://el34world.com/Forum/index.php?topic=19990.msg209086#msg209086)) I want to try and make the Warblers modulated/pitch shift signal asymmetrical. (#4 in drawing below.) I'd like to hear how that might sound.
2. Would doing that put stress on the SR coil and burn it up?
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5. If yes or no, any other way to knock it out of balance, make it asymmetrical?
I think you're thinking "asymmetrical" differently than what Siegmund claimed for their amp.
From the website:
"The asymmetrical frequency power amp separates the signal into upper and lower frequency ranges and plays them in stereo. The KT66 power tube amplifies the lower half of the frequency range through the 15" speaker and the EL34 amplifies the upper half through the 10" speaker."
So the only thing "asymmetrical" is use of 2 power sections and 2 different-sized speakers. They don't claim to have made the LFO or modulation asymmetrical. I don't know how they split the term/vibrato to drive each power section. It comes to mind they had the idea of copying Fender's early-60's harmonic vibrato, but sending the high-pass/low-pass signals to separate power amps to recombine in the air rather than in a preamp tube as Fender did.
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So the only thing "asymmetrical" is use of 2 power sections and 2 different-sized speakers.
I don't think so, only 1 power amp;
Speakers
The 15" speaker is a Weber 15A200 - a Jensen Alnico P15LL woofer version as used in vintage Leslie rotating speaker cabinets.
The 10" speaker is the new Tone Tubby Silver Bullet Alnico hempcone.
An audiophile grade custom-made crossover with air core coils and paper/oil capacitors divides the speakers into their respective frequency ranges.
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We're talking past each other in the 2 related threads.
http://el34world.com/Forum/index.php?topic=19990.msg209113#msg209113 (http://el34world.com/Forum/index.php?topic=19990.msg209113#msg209113)
It's unclear if there is only one crossover, or two. If there is one OT and one crossover, the claim that the "KT66's feed the 15" speaker" is bogus, because all tubes contribute to the output.
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> only 1 power amp;
Speakers
You say power amp then cite the speaker specs.
Power Amp
The asymmetrical frequency power amp separates the signal into upper and lower frequency ranges and plays them in stereo.
The KT66 power tube amplifies the lower half of the frequency range through the 15" speaker and the EL34 amplifies the upper half through the 10" speaker. A stacked Master Volume knob has separate controls for the left and right side.
The custom output transformer has a special design, perfectly balancing KT66 and EL34 tubes
Pretty screwy. Two tubes and one OT? Separate signals in each tube? I guess it is two SE amps, but a common OT, which cleverly avoids (most) DC idle current trouble. With hi-Z pentodes the opposed plates do not fight (much). It seems to be crossover before the tubes, full-range through the OT, then another crossover to split hi/lo for the 10" and the 15".
How this relates to a Hammond vibrato, I have no idea.
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Pretty screwy. Two tubes and one OT? Separate signals in each tube? I guess it is two SE amps, but a common OT, which cleverly avoids (most) DC idle current trouble. With hi-Z pentodes the opposed plates do not fight (much). It seems to be crossover before the tubes, full-range through the OT, then another crossover to split hi/lo for the 10" and the 15".
I think he's being liberal/inaccurate with his wording?
Class AB push-pull 38 Watts KT66/EL34
Tube rectifier 5AR4/GZ34
Octal preamp tubes 6SL7 and 6SN7
Sound Experience
The warm laid-back lower frequencies of the KT66 and slower 15" speaker provide the foundation and background of the soundstage,
with the brighter and lighter frequencies from the EL34 and faster 10" speaker floating on top into the foreground
How this relates to a Hammond vibrato, I have no idea.
Sigmund claims 'asymmetrical' signal for their Doppler amps/pedals.
So I asked;
And, because I saw the Sigmund Doppler Vibe pedal/Doppler amp combo ( link; http://el34world.com/Forum/index.php?topic=19990.msg209086#msg209086 (http://el34world.com/Forum/index.php?topic=19990.msg209086#msg209086)) I want to try and make the Warblers modulated/pitch shift signal asymmetrical. (#4 in drawing below.) I'd like to hear how that might sound.
2. Would doing that put stress on the SR coil and burn it up?
3. If no, would I need to use 3 pots, 1 after each pith shift stage?
4. Do you think adding a mix pot where I put it (#4) would do it?
5. If yes or no, any other way to knock it out of balance, make it asymmetrical?
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Sigmund claims 'asymmetrical' signal for their Doppler amps/pedals.
You're focused on "signal". The unstated implication/assumption is there is an asymmetrical LFO signal (is there? who knows?)
But Siegmund spends a lot of time talking about splitting frequency ranges, different output tubes, different speakers. I don't know that's the "asymmetry" but if it could just be that, then why spend time trying to chase a method to accomplish a task if you're not even sure what task to accomplish?
I want to try and make the Warblers modulated/pitch shift signal asymmetrical.
Scope the LFO and see that the signal is not symmetrical? Develop a new LFO which is asymmetrical? I'm not sure what these have to do with the SR-controlled signal stages.
Your delay ideas have some merit for different sounds. Jut don't do the normalled switching you have at #2, because that bypasses your who effect signal chain. Then again, the open-grid of #1 could be a noise problem.
I don't think you have to worry about burning up SR coils unless you're increasing the current through them, so no worries there.
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Scope the LFO and see that the signal is not symmetrical? Develop a new LFO which is asymmetrical?
I think if you want "asymmetrical" you'd be changing the LFO shape, which has nothing to do with the SR-controlled signal path.
Ok, I have a scope and a friend of mine started to show me how to use. I'll try and see if I can look at the LFO signal.
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Just don't do the normalled switching you have at #2, because that bypasses your who effect signal chain.
I normalled #2 because that's the dry signal send to the output mix pot. (Far right on the drawing.)
Then again, the open-grid of #1 could be a noise problem.
If I try it and it works/sounds good I can deal with that latter. Maybe shielded cable would be enough? But maybe I'll have to rig up some kind of switching.
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You're focused on "signal". The unstated implication/assumption is there is an asymmetrical LFO signal (is there? who knows?)
Yes my focus may be wrong. I'm thinking the Warbler signal is symmetrical because it's sooooo smooth sounding. I seem to remember that Sluckey looked at it on a scope and it was pretty good?
The Univibe pedal's signal is said to be a little asymmetrical because the little light bulbs filament heats up/cools down at a little different speed so the signal is a little lop sided and that's supposed to part of it's tone. But I've not heard anything about it's LFO. :dontknow:
I was also thinking about guys here knocking an amps PI out to fatten up the amps sound. The Warblers SR coil is flipping the 2 sides of a concertina.
So I was thinking maybe the Warblers modulated signal could have the same thing done to it? I could be wrong and maybe what your saying about the LFO is the way to go?