jimilee
Well-known member
Thank you sir.
Particle Accelerator - Alembic F-2B clone
- Thread starter vigilante398
- Start date
Mike McLane
Active member
BTW, fwiw you can easily fit Mallory 150’s in this build. . . .
Smrtokvitek
Well-known member
I am genuinely curious if you can hear the difference. Did you try to test different capacitors side by side in this circuit? There is a lot of information online about this but it is usually without evidence. I am currently working on a design where I would like to test it.
drgonzo1969
Well-known member
Nice! How does it sound?
vigilante398
Authorized Vendor
Personally I'm in the camp that if you can't measure it, it's not there. There can be measurable differences between different dielectric materials, but from one brand of film cap to another also film cap I'm not convinced the differences will be audible.
Naturally thoughts like this don't prevent extensive discussion and arguments, and it's not hard to find heated discussions on the matter on any guitar-related forum.
Mike McLane
Active member
The general gist I get is that the overhype is probably correct. I doubt you can hear any difference, but I do it cause it doesn’t cost much and eliminates any concerns that these units may be something less than serious preamps. The guy I built the “Deluxe Preamp” for has a good friend that used to work for Victoria Amps. He refers to those who unnecessarily belabor component specs as “audiophools”. Same comment applies to metal film vs carbon film & carbon comp resistors. Maybe he’s right, maybe he’s wrong, but if u pair this puppy with a good class d amp and speaker cab of your choice I bet you’ll have a great rig that’s very close to something you’d pay over a grand for, but is light/portable and a fraction of the price.
Mike McLane
Active member
Question for @vigilante398, if you were to use the second PA to add a higher gain "channel" would you modify the tone stack at all? I notice most channel switching amps work off of a single tone stack with the second tube (i.e. channel) solely adding gain. Like pairing the PA with a Space Heater which passes a flat signal.
vigilante398
Authorized Vendor
If you want to run two together for high gain I would probably remove the tone stack of the second and run that in the front end of the "clean" board. You'll just need to add a new coupling cap to replace where the tonestack was.
Mike McLane
Active member
In looking at the Duncan TSC I was thinking about just putting a 250K MID pot and call it a day. When max'd it gives a fairly flat curve and still has some tweakability of the Bass & Treb. What hookup mods would you do to the PCB? That might be a nice option to include in the build docs?
vigilante398
Authorized Vendor
I don't plan on listing mods in build docs, there are too many possibilities for me to list them all, so to make it easier on myself I won't list any. How you want to hook them up is really going to be determined to how you plan to use them. I would stick both in a box and wire the output from the one without the tonestack to the input of the one that has the tonestack, probably jumper the level pot on the first one.
Mike McLane
Active member
I finally got my first build back from my tester and spent quite a bit of time with it today thru a PowerStage 170 into a conventional speaker cab. What I hadn't realized, but discovered is that I thought that if I had the Gain set on a certain level I would get the same "sound" at different volumes depending on where the Volume was set. Au contraire mon frère. . . with Gain dimed I got still got super clean if the Volume was set low and got the grit I was expecting when the Volume was turned up. How does that work? Does the low Volume setting essentially function as a "choke point" of sorts that keeps the "big dogs from barking"? So the volume levels need to be modulated at the power amp?
Volume pot is going to change the impedance isn’t it?
I’ve got a alembic f1b clone thing (unfortunately not sushi box) and I’ve got some high pitched noise from tube or whevever, back off the volume from max and it rolls the top end off - depending what’s after it in the signal chain the impedance change means some pedals play funny with it.
szukalski
Well-known member
All we need is a tube power amp section which runs off 9V..
vigilante398
Authorized Vendor
I looked into it, best I can do right now is about 1W. But I'm still looking into it, I would love to be able to do more.
szukalski
Well-known member
Yeah, it's kinda tongue-in-cheek. I think there are some physical limits in play. Though 1W can push a lot of air.
My thoughts would be to build something with an in-built load box and send the signal to an IR loader, with the pre-amp coming from the pedal board.
Dysvalence
Member
A while back I saw this old article (https://desmith.net/NMdS/Electronics/NixiePSU.html) on nixie psus and theres a section on exotic FETs and beefier inductors for high current nixies; noob napkin math put some combinations into single ended el84 range but all the FETs listed are long out of prod so idk how useful this approach is
Mike McLane
Active member
For PA conversion to a OD/boost you suggested simply putting a coupling cap btw stages and bypassing the tone stack. The Space Heater had a 220K and 470K resistor inbtw the coupling cap and the GAIN pot which could easily be included into the existing PCB. What purpose did they serve and would they be a good adder to the mod?
Mike McLane
Active member
Is this OK or could you simply jumper Pin1 & Pin2 of the Treble pot, replace the C5, leave the tone stack values unpopulated and be done with it? How about the 220K resistor just preceding the Master Volume. . . in or out? With a 12AX7 this is a HOT TAMALE 
. I believe you mentioned trying a 12AY7 for something more tame.
. I believe you mentioned trying a 12AY7 for something more tame.
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vigilante398
Authorized Vendor
That would almost work, but you would need to jumper pins 2 and 3 on the Gain, as pin 2 is what takes the signal into the grid on V1B and you obviously can't leave it floating.Is this OK or could you simply jumper Pin1 & Pin2 of the Treble pot, replace the C5, leave the tone stack values unpopulated and be done with it? How about the 220K resistor just preceding the Master Volume. . . in or out? With a 12AX7 this is a HOT TAMALE
View attachment 50566
Mike McLane
Active member
How 'bout this? But I don't understand why?? Under normal PA wiring the signal flows across the Treble pot (jumpered in this case) to the Gain pot without any need for jumpering any Pins on the Gain pot. In looking at the Space Heater schem it appears the insertion of the 470K in the manner shown here works, but don't see how that would necessitate the pin jumpering you suggest.
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