sluckey's Deluxe Lite - BF-Tweed 2x12 Super

[BobL]

I recently did a full band shootout between my fancy-pants Imperial and the BF Princeton Reverb that I built into a Blues Jr/Tweed deluxe sort of setup, and really just found that the PR knocked the socks off of the Imperial, to my ears/setup.


I've been using the PR for my country band for a while, and it's perfect.  With the more rockin' band, my one complaint is that the PR gets very saturated when boosted for leads, and while it sounds good, but I'd like more headroom.  Now... I know that a DR and PR won't really sound the same, but... a DR still sounds pretty dang nice.


Anyway, I built a 5E8 a few years ago, and liked parts of it, but ultimately I'm a blackface sort of guy, not a tweed sort of guy.  I also basically never use the reverb or trem on the PR.  Not huge on spring reverbs, and the stuff I use trem for, outside of the studio, where the PR will fit the bill, I prefer having a tap trem, so I use a pedal.  I also wished I had a mid control the last time I had a DR...


What that all leads to is that I'd like a tweed cab with a non-trem, non-verb blackface circuit with a mid control and two speakers... which led me to sluckey's Deluxe Lite - looks like exactly what I am looking for, circuit wise.


My initial question comes down to: what do I do about a chassis if I build this?  The PTs for DRs won't fit the cutout in a 5E8 chassis.  The pre-drilled holes for controls and tubes are not entirely ideal, but I'd probably be adding in a custom faceplate which could cover up unused holes, but I'm a bit stuck trying to come up with a solution for the PT.  I'd be 5/8" too big lengthwise, and 1/2" too big across... I could cut a plate to hold the PT that then bolts to the existing holes, but I don't necessarily have the setup to do that. :)  Is there maybe another tweed style chassis that would be a better fit for this project?


Also, circuit wise, using two speakers, would I want to switch to 100K for the NFB tail resistor? Seems like that was done on multiple speaker AB763s?  Anything else I'm not thinking of w/ a 2 speaker setup?


I think I would have room to just put the 'dog house' caps on the end of the same board.  sluckey, I saw you used 20uF caps on this board, and your layout shows 22uF... regular AB763s seem to use 16uF - curious on your reasoning there - is it just to tighten up some low end?


Thanks in advance for any insights...

[Tony Bones]

Being profoundly lazy, I'd just keep the 5E8 PT. For that matter, I'd probably keep the 5E8 OT too and just run 6L6's, though the B+ voltage is probably low enough to plug in 6V6's. Just replace the preamp and PI with AB763. Use Slucky's Deluxe Lite for inspiration...

[ac427v]

100 ohms will work better than 100K ohms for the NFB tail resistor

[sluckey]

sluckey, I saw you used 20uF caps on this board, and your layout shows 22uF... regular AB763s seem to use 16uF - curious on your reasoning there - is it just to tighten up some low end?

There are more AB763s that use a combo of 70µF and 20µF rather than 16µF. But 16, 20, 22 are all the same to me. However, 22s are more common these days and cheaper too. I blame my drunken draftsman for showing 20 on my schematic and 22 on the cap board layout.   

[BobL]

Being profoundly lazy, I'd just keep the 5E8 PT. For that matter, I'd probably keep the 5E8 OT too and just run 6L6's, though the B+ voltage is probably low enough to plug in 6V6's. Just replace the preamp and PI with AB763. Use Slucky's Deluxe Lite for inspiration...

I worry about this changing the character of the amp too much... if anything, I'd want to move further towards Princeton territory than towards higher wattage amps.

100 ohms will work better than 100K ohms for the NFB tail resistor

Haha, yes... yes it would. We're gonna call that a typo. :)

There are more AB763s that use a combo of 70µF and 20µF rather than 16µF. But 16, 20, 22 are all the same to me. However, 22s are more common these days and cheaper too. I blame my drunken draftsman for showing 20 on my schematic and 22 on the cap board layout.   

Gotcha.  I'm trying to get a handle on things to do on that cap board to adjust low end flab - it seems that both using the two 100uFs in series, which is what I understand your alternate board to be, and just changing the value of that first cap to 32 might be sonically very similar?  Am I understanding correctly that both of those would get you to around 50uF filtering?  Thoughts on one approach vs. the other?

[BobL]

Being profoundly lazy, I'd just keep the 5E8 PT. For that matter, I'd probably keep the 5E8 OT too and just run 6L6's, though the B+ voltage is probably low enough to plug in 6V6's. Just replace the preamp and PI with AB763. Use Slucky's Deluxe Lite for inspiration...

Also, at this point we're basically talking a Super Reverb, aren't we?


Hrm... it's a thought...

[sluckey]

Both boards offer about the same filtering. The top board with parallel 22µFs (44 total) is for the lower voltage AB763s such as Deluxe Reverb, Tremolux, and Vibrolux. The bottom board with series 100µFs (50 total) is for the higher voltage AB763s such as Pro Reverb, Super Reverb, Showman, Twin Reverb, etc. High voltage caps were costly back in the '60s, so Fender chose to use two lower voltage caps in series to get the job done at a lower cost.

There's really nothing to do on that cap board to adjust low end flab.

[BobL]

Both boards offer about the same filtering. The top board with parallel 22µFs (44 total) is for the lower voltage AB763s such as Deluxe Reverb, Tremolux, and Vibrolux. The bottom board with series 100µFs (50 total) is for the higher voltage AB763s such as Pro Reverb, Super Reverb, Showman, Twin Reverb, etc. High voltage caps were costly back in the '60s, so Fender chose to use two lower voltage caps in series to get the job done at a lower cost.

Thanks for the explanation...

There's really nothing to do on that cap board to adjust low end flab.

Oh, I was under the impression that the loose low end on a DR had to do with the value of the caps here being lower value, and that you maintained a more consistent voltage with higher values here?


Building this as a Super is seeming like a viable option... it looks like the circuits are almost identical - just a few different values here and there.


Seems like your choice of a 25K mid pot is probably a good idea - gets the same curve but ability to push more mids.  .022uF on the mid cap also seems like a better spot to be adjusting....


So... a 13"x3" board will fit in the 5E8 chassis, which means I could have the cap board on the same board as everything else.  I'm assuming there would be no reason not to do this, and it was originally moved just due to space... the 5E8 has all those caps at the transformer end of the board.

[BobL]

Anyone aware of anywhere that would have layout/dimensions for the controls/faceplate on a 5E8?  Not having much luck finding them...   It would be a shortcut to designing my own faceplate w/ the different controls, but using the existing holes in the chassis.


I did my last tweed/BF faceplate from scratch, but it could've been easier... :)

[BobL]

sluckey - was there any particular reason your mid control wasn't in between your bass/treble controls in your layout?

[VMS]

Some chassis drawings on weber site.
Not sure if they are same as fender and if they are any use for you.


https://www.tedweber.com/chassis-dimensions/

[BobL]

Some chassis drawings on weber site.
Not sure if they are same as fender and if they are any use for you.


https://www.tedweber.com/chassis-dimensions/

Oh, excellent!  I might need to adjust a small amount when I get the chassis (Mojo), but this will let me get the bulk of the work done beforehand.


Thanks!

[sluckey]

sluckey - was there any particular reason your mid control wasn't in between your bass/treble controls in your layout?

Yeah, I've always been a TBM kinda guy.

Look at the schematic. Notice how the tonestack just kinda flows from top to bottom... treble, bass, mid. Now look at my layout. It flows just like that. And the layout wiring looks so much neater too! If you need to put the pots in the Fender lineup just make your wires longer . When your done, twist them around like Leo did. 

You had mentioned using a 3" board (I assume Hoffman's 3-1/8" board). And combining the cap board. I have a different layout for this same amp using a 3-1/8" board. It's only 5" long. This board is designed to easily fit a 12x6.5x2.5 chassis (such as Hoffman's Stout chassis). LMK if you are interested in this layout. My original Deluxe Lite layout used a narrow board that would easily fit a tweed style chassis better.

[BobL]

sluckey - was there any particular reason your mid control wasn't in between your bass/treble controls in your layout?

Yeah, I've always been a TBM kinda guy.

Look at the schematic. Notice how the tonestack just kinda flows from top to bottom... treble, bass, mid. Now look at my layout. It flows just like that. And the layout wiring looks so much neater too! If you need to put the pots in the Fender lineup just make your wires longer . When your done, twist them around like Leo did. 

You had mentioned using a 3" board (I assume Hoffman's 3-1/8" board). And combining the cap board. I have a different layout for this same amp using a 3-1/8" board. It's only 5" long. This board is designed to easily fit a 12x6.5x2.5 chassis (such as Hoffman's Stout chassis). LMK if you are interested in this layout. My original Deluxe Lite layout used a narrow board that would easily fit a tweed style chassis better.

I have an extra 3"x15" board I was going to cut to 13...


Maybe I'm already looking at your non-tweed layout?


I was looking at this one:
http://sluckeyamps.com/misc/AB763_Deluxe_Lite.pdf


Is the other less compact, or more?  I'd be interested to see it either way.


Since this is going in the 5E8 chassis, it will be long and narrow... I was just going to combine the two boards from that link w/ the cap board on the left end of the circuitboard.  The template for the main board printed at 3 1/8" seem to all fit well within the 3" board anyway, and I was just going to adjust the cap board spacing down to match.

[sluckey]

This is actually part of a bigger project but it may be useful to you...

[BobL]

This is actually part of a bigger project but it may be useful to you...

Seems like a smaller project. ;)

Thanks!

[sluckey]

That's because I cut the rest of the story out. 

[BobL]

Got everything on the way for this project except speakers...


I really like the Jensen P12Q I have in my Princeton, so considering a pair of those, but curious is anyone has other speakers they like in AB763 amps.


Other question: Anyone have any thoughts on speaker wiring for a 2x12 Super?   Would the prevailing wisdom/thinking be to use both jacks and run two 8 ohm speakers in parallel for a 4 ohm load? Would there be an argument to use one jack and wire the speakers in series?  Any argument for/against running two 16 ohm speakers on the jacks with the 8 ohm tap instead? Two 32 ohm speakers on the 16 ohm tap?


I ask the latter because I've seen a couple good looking deals on used P12Q sets, but they are 32 ohm speakers.

[shooter]

I've seen a couple good looking deals

as long as you keep impedance where the amp expects, how you get it shouldn't matter.  I had a 16ohm laying around, found a great deal on another 16, made my 2 X12 cab 8ohm, (what my amp expected).  works great for 1/2 the price 

[BobL]

Oh, and I just checked my OT, and I only have 2, 4 and 8 ohm taps... so I guess that dashes my dreams of cheap speakers. :)

[sluckey]

I have used a P12N and a C12N with my AB763 amps. Both sound very Fendery to me. C12N is much cheaper than P12N.

Anyone have any thoughts on speaker wiring for a 2x12 Super?   Would the prevailing wisdom/thinking be to use both jacks and run two 8 ohm speakers in parallel for a 4 ohm load? Would there be an argument to use one jack and wire the speakers in series?

I would put both speakers in one box and only use one jack. Do the parallel or series wiring inside the speaker box. The only reason to use two jacks would be if you have two separate speaker boxes.

[BobL]

I have used a P12N and a C12N with my AB763 amps. Both sound very Fendery to me. C12N is much cheaper than P12N.

Anyone have any thoughts on speaker wiring for a 2x12 Super?   Would the prevailing wisdom/thinking be to use both jacks and run two 8 ohm speakers in parallel for a 4 ohm load? Would there be an argument to use one jack and wire the speakers in series?

I would put both speakers in one box and only use one jack. Do the parallel or series wiring inside the speaker box. The only reason to use two jacks would be if you have two separate speaker boxes.

Yeah, they are both going in the same 5E8 cab.  I guess I'll just wire them depending on what I can find deal wise.


I have a pair of C12Qs here that I really did not like - felt very harsh to me vs the P12Qs.

[BobL]

I've been looking at the possibility of using 6V6s in this w/ the 6L6 transformers.  As I understand it, I could do it if the 6V6 was burly enough (people say the JJ 6V6S would work), and then I guess I'd also want to run the 4 ohm tap into an 8 ohm load as well?


Thoughts?

[Tony Bones]

5E8 schematic shows 400V on the plates of the 6L6's. That'll probably go up a bit with 6V6's, but Deluxe Reverbs usually run around 425 to 450. I'd say you're good to go. If you don't like it you can always change it later, but it looks like a safe experiment to me.

[BobL]

Power section I'm building is based off of the Super Reverb... I think it's showing me 460 on the plate? Also seeing that on a Twin Reverb, but that is an amp that people talk about needing modification in order to run 6V6s as well... I get the impression it isn't that easy?  Seems it's a question of current, not just voltage?


https://el34world.com/charts/Schematics/files/Fender/Fender_superreverb_aa763.gif

[BobL]

I guess I could add a switch to go between the 8 and 4 ohm taps in case I wanted to try this w/o rewiring, eh?

[Tony Bones]

Where did you get the PT? (Brand, part #.)

I had guessed that you had a functioning 5E8 clone. If so, then measure the voltage at the plates of the 6L6's. If not, then put the PT on the bench, apply wall voltage to the primary, and measure the no-load voltage at the secondary. (I don't need to tell you to make sure none of the wires are touching, do I?)

Let's figure out what you really have.

[BobL]

Where did you get the PT? (Brand, part #.)

I had guessed that you had a functioning 5E8 clone. If so, then measure the voltage at the plates of the 6L6's. If not, then put the PT on the bench, apply wall voltage to the primary, and measure the no-load voltage at the secondary. (I don't need to tell you to make sure none of the wires are touching, do I?)

Let's figure out what you really have.

Yeah, no - this is a new build.  Just using the 5E8 chassis!


PT is Mojotone, 762. It's their Blackface Bassman PT.

[BobL]

It looks like compared to their Deluxe PT, the main difference is the amperage, not the voltage - 250mA vs 150mA.


Here's the DR PT, the 761:

[sluckey]

You should use that PT with 6L6s.

[Tony Bones]

You should use that PT with 6L6s.

Unless you really, really want to try 6V6s. 

[BobL]

Since I'm moving the cap board to the left side of my board for this build, would there be any reason not to use the common power ground for the B+ D ground rather than the preamp ground, sluckey?

[shooter]

D ground

It's not so much the location, but the application, preamp signals are delicate things, they need to stay away from the dirty power, least they get a disease that can't be cured 

[sluckey]

Since I'm moving the cap board to the left side of my board for this build, would there be any reason not to use the common power ground for the B+ D ground rather than the preamp ground, sluckey?

I would not do that. Since you are putting the caps inside the chassis I suggest you spread them out rather than put them all at the end of the board. IOW, put the node D cap down at the preamp end of the board.

[BobL]

Since I'm moving the cap board to the left side of my board for this build, would there be any reason not to use the common power ground for the B+ D ground rather than the preamp ground, sluckey?

I would not do that. Since you are putting the caps inside the chassis I suggest you spread them out rather than put them all at the end of the board. IOW, put the node D cap down at the preamp end of the board.

Oh, interesting. Ok.

[BobL]

I don't seem to have a 270k resistor... If I use a 220k in place of the 270k at R14, will this have much impact at all?  This is in the section that says 'can be removed if higher gain is desired', so my guess is the only potential impact might be to increase gain a very, very small amount?


Using this schematic: http://sluckeyamps.com/misc/AB763_Deluxe_Lite.pdf

[sluckey]

Making R14 smaller will decrease the gain. I would try with no resistor for R14 and see how you like it. If it sounds too gainy for you then clip in some resistors. Experiment with different values until you hear what you want.

270K was chosen because that's what the normal channel would see from the loading of the vib channel, ie, 220K mix resistor + 50K INT pot.

[BobL]

Gotcha. Thanks!

[dude]

Why not take all of the shaded area caps and resistors out and put in a master volume, use a 1MA pot.  I added a M/V with this same exact schematic, I was able to cut the master to cut some flab and cleanup the amp. Works great. I also use a lower cathode R, on input gain, from 22uf to 4.7uf, that really took the flub out. I used a PT with much lower voltage, B+ around 350, fixed biased.


Just try these changes one at a time, first the 4.7uf cap, then wire the M/V, I think you'll like what you get. These changes took the flub out, boosted the headroom and sounds very Country to Rock and Roll. The speakers have a lot to do with it too, Blue Fender Alnico Eminence's might get you where you want.


al

[BobL]

Why not take all of the shaded area caps and resistors out and put in a master volume, use a 1MA pot.  I added a M/V with this same exact schematic, I was able to cut the master to cut some flab and cleanup the amp. Works great. I also use a lower cathode R, on input gain, from 22uf to 4.7uf, that really took the flub out. I used a PT with much lower voltage, B+ around 350, fixed biased.


Just try these changes one at a time, first the 4.7uf cap, then wire the M/V, I think you'll like what you get. These changes took the flub out, boosted the headroom and sounds very Country to Rock and Roll. The speakers have a lot to do with it too, Blue Fender Alnico Eminence's might get you where you want.


al

Not really a fan of MVs... also not sure how you boost headroom or add clean by using one...


I'm also not following what you are are referring to with caps... I don't have a 22uF cap on there.  Are you talking about the .022uF cap at C4 changing to a .047uF?


Planning to build this pretty stock, see what I get, and then adjust if needed.

[sluckey]

That's what I did on my TDR. But you must leave C6 in place to do that.

[dude]

NO, not C4. I'm talking V1A, C1 cathode from 25uf to 4.7uf. And I agree with you built it as written first, then make one change at a time. Just suggesting changing V1A cathode cap C1 to ground from 25uf to 4.7uf, this is well know to decrease flub.


Taking all the shaded parts out to PI, is basically what Sluckeys says about removing R14, lower gain, the M/V will lower the gain to the PI, just enough to cut some gain, I usually only turn it a quarter turn, maybe a half. Just saying try it. Correct me Sluckey if I'm wrong.


al



 

[sluckey]

Taking all the shaded parts out to PI, is basically what Sluckeys says about removing R14, lower gain, the M/V will lower the gain to the PI, just enough to cut some gain, I usually only turn it a quarter turn, maybe a half. Just saying try it. Correct me Sluckey if I'm wrong.

I already did. 

[dude]

Taking all the shaded parts out to PI, is basically what Sluckeys says about removing R14, lower gain, the M/V will lower the gain to the PI, just enough to cut some gain, I usually only turn it a quarter turn, maybe a half. Just saying try it. Correct me Sluckey if I'm wrong.

I already did. 

.                                                    You mean leave the .047 before the m/v and the .01 after? I can see the .01 before PI but why the two caps?  Doesn’t the .01 block any voltage.

[BobL]

So, to be sure I'm clear about R14 - we are talking completely removing that part of the circuit - not just replacing the resistor w/ a wire, correct?


Tell me if my understanding of what this is doing is correct (sorry, musician, not engineer).  The 270K after C6 is basically just shunting (is that the word I want?) a limited amount of the signal coming out of V1 to ground, so it reduces what goes on to V2?  Removing R14 just lets more signal hit V2, whereas *reducing* R14 would allow more signal to go to ground, which would reduce gain?


One of my worries w/ this amp vs my Princeton is that I might end up with so much headroom that the amp is a bit sterile by comparison (though I also need more headroom that I currently get w/ the Princeton).  It seems that this might be part of the solution.  I know Leo designed these to be as clean as possible, so undoing some of his good work might be the ticket.

That's what I did on my TDR. But you must leave C6 in place to do that.

You are referring to leaving C6 if you inserted the MV, yeah?

NO, not C4. I'm talking V1A, C1 cathode from 25uf to 4.7uf. And I agree with you built it as written first, then make one change at a time. Just suggesting changing V1A cathode cap C1 to ground from 25uf to 4.7uf, this is well know to decrease flub.

Gotcha.  I seem to remember doing something along this line on the first amp I built, which was a JTM45.  I'll remember to try this if the low end feels loose.

[sluckey]

You mean leave the .047 before the m/v and the .01 after? I can see the .01 before PI but why the two caps?  Doesn’t the .01 block any voltage.

Come on dude. You can do this. Just look at the schematic. Didn't you just ace last week's quiz?

[dude]

Ok, now I’m confused, is that .047 on the lines of a smoothing cap...? Or is a cap always needed before a m/v pot to keep any voltage out.., and after to the PI...? I’ll keep reading about caps before the PI, if I can’t figure it out, hope you give me a hint.    BobL, I think you have the reasoning down with that 270k to ground. Also, sluckey is saying the m/v goes between the .047 and .001, meaning keep the .047 in the shaded part for master volume. But remember that master when turned down a bit, dumps some signal to ground. All the way on is like not having those shaded components, signal straight to PI, but Sluckey says keep the .047 when you put in a master and i’m Trying to figure out why. Sorry, if I butted in your post, if I confused you ask sluckey, I’m sure he’ll help.

[BobL]

  BobL, I think you have the reasoning down with that 270k to ground. Also, sluckey is saying the m/v goes between the .047 and .001, meaning keep the .047 in the shaded part for master volume.

Gotcha. Thanks for confirming.

But remember that master when turned down a bit, dumps some signal to ground. All the way on is like not having those shaded components, signal straight to PI, but Sluckey says keep the .047 when you put in a master and i’m Trying to figure out why. Sorry, if I butted in your post, if I confused you ask sluckey, I’m sure he’ll help.

No worries at all!  I learn something every time.

[dude]

Ok, the .047 will cut any freq. lower out, so you don’t want low freq. being driven to PI (too much distortion) and the .001 after the mv lets higher freq pass, also stops voltage leaks to PI (only need one cap to cut voltage). If the amp is too bright take the .001 out, am I on the right track? Told you I’d be lucky to get a C yet ace this...

[BobL]

Got my faceplate today... last time I had them print white ink on black plastic, but this time I went w/ the laser etching, and I'm glad I did. Quite happy with how it turned out.