6V6 Plexi build

[Tone Junkie]

Just finished the build and working out the bugs . To Slucky I wanted to ask on your notes you changed the NFB to 22K saying not enough NFB what did you accomplish with that . I'm guessing that was your notes.
I was chasing some miner oscillations when cranked to 10. I only had a couple tricks left to try. I switched mine to 22K . But cant crank her up till tomorrow.
Thanks Bill

[sluckey]

I could not hear a difference when totally disconnecting the NFB with the 100K so I increased the NFB by using a 22K. Now I can hear a difference and the presence control has more effect.

Did you follow my layout plan or did you follow Hoffman's plan, or some other plan? As for your minor oscillation, have you reversed the OT primary plate leads to see if that is the cause?

[guitardude57]

Minor oscillation on 10 would not be reversed plate wires.




The oscillation solutions on this amp, are related to moving your V1 wiring
around, to find what is interacting.  This is the sensitive part of the amp.


Also, try removing the bright cap off of the bright volume pot.


You don't need it... and is an offender to chirping.

[sluckey]

Minor oscillation on 10 would not be reversed plate wires.

I would not dismiss it so quickly. Many times reversed NFB phase does not result in a howling or ear splitting squeal. Symptoms depend on the particular circuit and the amount of NFB. Sometimes the symptoms are just a more gritty or distorted sound or even an unpleasant sustain on certain notes, especially when there is a presence control involved. And the builder may not even know it because distortion is often a desirable trait for a guitar amp. This very scenario has come up repeatedly in this forum.

I'm not saying that this is absolutely the problem with this amp. But I am saying anytime there is a global NFB circuit involved, a good technician will take steps to insure the phase is correct. After all, there's only a 50/50 chance you got it right.

[guitardude57]

Sure I agree it may be possible.  Anytime I encountered a reversed plate set up..it howled like a bitch straight on.

[Tone Junkie]

Reversing the plate wiring took care of most of the problem . The only other time I had to reverse the plate wires it howled no matter were the volume was. So that wasn't my first thought to try . I'm still cleaning up some wiring but it only howls now with everything maxed then turning the presence up to 9 or10 . I have a .68 cap there going to go back to .1 to see if that fixes it. First thing I did was tighten up the wiring around the first gain stages. Then added some shielded wire. Plus it got worse when I lowered the NFB to 22K I new right away what it was then.
Thanks Bill

[Tone Junkie]

Oh I forgot don't use the bright caps on my plexi style amps anymore don't like em. Originally it howled when anything was past 8 on the master volume. It was quite late when I wrote last night.
Bill

[Tone Junkie]

So just an update on this. I had still been dealing with a minor oscillation trying to get it so i could jumper the channels. Nothing was working did all the usual. chopsticking, changing tubes, checking all ground points, adding shielded cable, No luck. Recently I have been using Merlins ground scheme with the 10ohm resister and .1 cap worked without a hitch. So I put  my wired switch  onto the pre amp ground and other end to star ground next to the plug ground, then flipped the switch. Silence at all volumes even with the channels jumpered together . I don't know if I over heated the components I was using or that ground just didn't work for that circuit. But it sounded nice to jumper the channels and get that plexi growl again. Nice with the 6V6s dont have to destroy my ears to get the good tone. Ok so its still a bit to loud but that's what the mv is for.  LOL
Bill

[dude]

On this subject, what is the best Hammond Organ chassis with it's transformers and choke to use for either Sluckey's, Huss's  or Doug's 6V6 Plexi.


Also, any place I can buy face-plates (anyone who has had sets made and has access to sell a set) to fit the suggested Hammond chassis?


Thanks as always,
al 

[sluckey]

On this subject, what is the best Hammond Organ chassis with it's transformers and choke to use for either Sluckey's, Huss's  or Doug's 6V6 Plexi.

I used the AO-43 as a donor for mine. It has a suitable PT, OT, and choke.

[dude]

Thanks, any suggestions where I can get a Plexi face plate for that Hammond A0-43 with out going thorough having a custom one made.
Maybe someone who has had one made to fit that chassis, and has access to copies. Doesn't matter who's name is on the FP's.


al

[sluckey]

I'm fond of my little DYMO label maker.

[dude]

Yeah, I heard ya. Just that I see all these fantastic FP's, even your's is pretty cool is that a DYMO label maker, pic?.  BTW, what DYMO stand for?


A lot of my conversions and an A0-35 have stickers on them, looks pretty crappy. People come over and remark how great they sound and say you need a nice face plate... 


Doug has some FP, but no 6V6 Plexi and might be hard to find one to fix the A)-43...?

[sluckey]

DYMO is a brand name. Here's one...

https://www.amazon.com/gp/product/B00464E5P2/ref=ox_sc_sfl_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

The labels you see on my Plexi 6V6 are black printed on clear tape. There are lots of other choices of tape too.

[labb]

Sluckey's (the ones he does himself) look more like water slides to me.

[drew]

In the past, I have used the free software from Front Panel Express to design a panel, then, instead of having them make the panel, I saved ( "printed") the project to a PDF. I then took the PDF to an Office Depot and had it printed on heavy color photo stock, trimmed it to size, and had the resulting paper strip laminated.  It's some work, but costs a lot less than having a real plate made, and it looks pretty good.  The software had a gold color and a sans serif font which got at least somewhat close to looking Marshall-ish.


If you're inclined to try this, I would suggest verifying that it's still possible to make the software give you a PDF file *before* you get too deep into it.

[sluckey]

If you're inclined to try this, I would suggest verifying that it's still possible to make the software give you a PDF file *before* you get too deep into it.

There are several programs that simply appear as a pdf printer driver. Just select pdf printer whenever you want to print anything from any program. I use Adobe PDF and have it set as my default printer.

[labb]

What Drew said. I have done several that way and it works pretty good. I usually put a few coats of clear on top of it.

[DummyLoad]

for a PDF printer i use bullzip - free version phones home with usage stats.


--pete

[PRR]

The Brother tape-label machines are very handy and less chunky than the DYMO. I use them on house-wires, the kill knob on my tractor, tool drawers. They don't have the strong curl the old DYMO tape had, so may be less likely to pop-off in the center. There's several font sizes (more on the $$$ models), unlike DYMO where you had to change the wheel and they were hard to find. The tape comes in many colors. OTOH the Brothers use batteries: 6 or 8 AA cells every year. The DYMO just wears out your hand.

EDIT: hey, that link isn't the DYMO, it is a Brother-like PC-attach with a DYMO name! I was thinking of the old hand-squeeze gun DYMO. Are they still around? Yes.

PDF printer: Win2PDF is old but good. Un-paid version adds an extra page with their link on it; obviously you throw that away. I was doing so much PDF-ery that I paid for the license, must be 15 years ago, still working fine. Maybe not the smallest output files.

[sluckey]

I actually have this older DYMO LabelManager 210D. Confusing to use. I have to relearn it every time I need it. I keep saying I'm gonna replace it with that USB Plug 'n Play model. It uses the same tape cartridges and will hook into any of your favorite word processors. No more searching for a # symbol! 

[Tone Junkie]

I like Sandy Henry at precision design she does a real nice job. Fairly cheap for a one off design.
I can show  you how I send it to her  if your interested. I don't use visio like the other guys do. I  just draw it out adding measurements from the end to each hole, the size of the hole, length and width. she takes care of the rest . Theres more to it but look at her site copy from the ones she's already done.
Bill

[dude]

Thanks, good advice