Blast Off....Got'er Dun

[Blind Lemon]

Sure........I wanted to parallel V1 in my amp to take advantage of the extra triode in this circuit and just used a common plate riz and split the cathodes. I split the cathodes because I wanted to see if changing values of the caps would create different harmonics. I started out with a 22/25v on V1a and a .68/25 on V1b. What I have settled on so far is V1a the same but put a 10/25v on V2b. I have been working on the TS and first coupling cap to shed a little brightness and bring the Mids up front a little more. RJ suggested an 18K mid riz, but I have 25k in now, will probably end up in a 25k pot with a 10k riz between the wiper and ground. I am trying to voice this amp for my Strat and LP. Btw, if you have a Strat with vintage PUPs, think CS 54s, a .0047 first coupling cap sounds pretty good. I'm trying to find the sweet spot for both guitars. The neck PUP in this LP is crap and the bridge is Ok. I've got a new set of hot PAFs coming, and not having to worry about crappy PUPs should make this job easier.

Also with the way I built mine, even with out a bypass cap on the third troide this thing rocks. Even with the amp on 3 or for you can get were you want to go by using the guitar volume, clean to screaming feed back. Of coarse with this amp I'm sure that it would just be a lite workout for Glem on the guit. volume compared to the Express I have seen him play on Youtube.

I'll post more as it comes.

BL

[Blind Lemon]

Ended up with a 56k plate riz feeding the paralleled first tube and about a 22 or 27k Mid riz and 750pf for the first coupling cap. Left the Bright cap in.

It sounded so good the first guy that played it ended up buying it.

BL

[RJ Guitars]

Ended up with a 56k plate riz feeding the paralleled first tube and about a 22 or 27k Mid riz and 750pf for the first coupling cap. Left the Bright cap in.

It sounded so good the first guy that played it ended up buying it.

BL

Blindman, that is very cool. Thank you for the technical info... I think that is my favorite part of this forum (learning about the various tweaks).

Did you try that first gainstage unparalleled and compare the results? I have a build of my own with this tweak and am just now getting around to putting it into a cabinet.

What did it accomplish with the change to the 56K plate resistor?

I think I understand that mid resistor change... from those values I would expect that you boosted the mids up quite a bit. I think that all of my future Rocket inspired builds will use a mid pot - maybe a 25K pot with a 10K fixed resistor on the wiper? what do you think?

Also, say more about what happened with that that 750pF swap?

Thanks again for the info and glad the amp worked out so well.

rj

[Blind Lemon]

RJ's?

Did you try that first gainstage unparalleled and compare the results?

Nope, to be honest I never thought about it.

What did it accomplish with the change to the 56K plate resistor?

As a rule when you parallel triodes you need to half the plate riz and the cathode riz for the same gain. I split the cathodes on that tube and both cathodes had stock 1K5 riz. As far as what the cathodes new they weren't paralleled. I did not split the plates, 1 plate riz, so it was seeing paralleled triodes. Knowing the above rule I split the 220K to a 100k to start with. With the paralleled triodes, I had been told, that as a general rule if you count 1 triode's gain as 1X, when you parallel them the gain will be about 1.3X. Anyway to make a long story just a little longer, the amp sounded a little more gainy/raty than I wanted, so I basically halved the plate riz again to clean it up. To increase/decrease gain by means of the plate riz, increase the riz = increase gain and to decrease gain = decrease the riz value.
RJ, I guess the short answer would have been it cleaned it up a little.

I think I understand that mid resistor change... from those values I would expect that you boosted the mids up quite a bit. I think that all of my future Rocket inspired builds will use a mid pot - maybe a 25K pot with a 10K fixed resistor on the wiper? what do you think?

You and I are thinking alike on that one, your way you get the stock 10k with the pot turned all the way down to 35k on the upper end. And yes it did bring the Mids out front more....at least to my ears.

Also, say more about what happened with that that 750pF swap?

I was just trying to warm this thing up just a little bit. I tried a 4.7N (.0047uf) first and it sounded good with the Strat, but not very good with the LP. And again I think the LP has a CRAP neck PUP. So I backed it down to a 750pf (500 is stock). Someone out there may run the numbers on this and say I'm crazy( ), but that's where I ended up. The 4.7n really knocked the top out of it. And Btw if I didn't say before I left the brite cap in with the way I ended up.

Now RJ I got a question for you......got any more parts to sell. The guy I sold this one to plays in a band and can't wait to show it off. May mean more biz.

BL

[RJ Guitars]

Now RJ I got a question for you......got any more parts to sell. The guy I sold this one to plays in a band and can't wait to show it off. May mean more biz. BL

Thanks for the good words BL - I always have more parts... My machine shop guy just can't stand to make a few a time so I think I have about 30 Chassis' in the shop now. You name the tube compliment and if I haven't got a chassis for it, I have a blank I can make up. My wife and bank account will verify that I'm pretty weak on the profit end of things but watching these things come to life has been a blast!

Also, thanks for the good tweak tutor you have provided. This amp is pretty straight forward but has a world of potential options. You'll probably start seeing some of your tweaks show up in other threads and a kind word back to you seems in order. Good work Mr. Blind Lemon!

rj

[SiriusAbbott]

It sounded so good the first guy that played it ended up buying it.

that would be me!!!
this amp is truly the best sounding amp I have EVER played through....and I only played through it for 5 or 10 minutes
understand that I have been playing guitar for 32 years,and have owned 70-80 amps...mostly tube,I'm currently running a modified JCM 900 and an equally twisted Ampeg VL-1002.
but I found a need for something.....more!
a truly expressive amplifier,an amp that a subtle volume knob twist changes the entire sonic palette.
so I called my local amp expert.......and he made the intro.
I found that sonic knockout.
and Blind Lemon built it

and BTW,thank our mutual associate for turning me onto this forum,its a load of good info indeed!!!!!

[RJ Guitars]

It sounded so good the first guy that played it ended up buying it.

that would be me!!!...

Welcome to the world Sirius!! The Amp world where even the first one is not free but you get addicted anyway!

rj

[Blind Lemon]

Yes sir SA, I am the Blind Lemon. Thank you for the kind words.

Our mutual friend, Mr Rick, is truly a guru. I have been lucky to work with and learn from him.

BL