Not quite a rebirth after all...

[yankeerob]

Back to my ailing Dv - the prob I'm having is somewhere between the wiper on the vol pot and pin 7 on V1(B) and as I can't get at the solder side of the board when it's powered up (like I've had time to build a jig or the money to splash out on a spare PT, choke, OT, and dummy load, geez!) I'm a bit in the dark. We (my ex-BBC engineer friend John who has loadsa cool ex-BBC test kit & I) traced a test tone with a scope from the input through to the wiper but it doesn't arrive at pin 7 and there's not a hell of a lot in between (the circuit's identical to the Dx - input-> V1A -> vol pot -> relay -> 10K resistor -> V1B) the weird part is when the board's out I get a 10K DC resistance between the wiper and pin 7 so the relays passing voltage through it when the board's out of chassis but the circuit is interrupted somehow when it's in and powered up...

Other things of note -all the supply voltages we've checked (B+, X, Y & Z) seem fine if a tad higher than spec - maybe 20 or so volts higher than what's on the drawing but I figure it's just idling so it's no big thing, right? The board's been in and out that many times that the danged heater supply wires between V1 & V2 finally frayed & broke so I've replaced that now

I can only surmise that K1's given up the ghost in some way - unless somethings wrong with the control voltage which is causing it to break but not quite make when it's powered up? You can hear a switching noise when you press the channel switch in and out but nothing's coming out of either channel - it's driving me bonkers as it seems to be something so damned simple and the amp sounded great until this latest drama

Any ideas? (besides 'do I live near a cliff' and 'buy a real amp' )

Have already priced up parts to build a Weber 6O100 clone as I can get my hands on British style PT's and OT's no prob and will likely go for a 5A40 after that (now that I've gotten my hands dirty I've decided to take it in bite sized chunks before moving onto a real animal)

But I would like to get this sorted so I can concentrate on building something else for a while

[NTBluesGuitar]

I can only surmise that K1's given up the ghost in some way - unless somethings wrong with the control voltage which is causing it to break but not quite make when it's powered up? You can hear a switching noise when you press the channel switch in and out but nothing's coming out of either channel -

Could be cold solder joints on the relay. Wouldn't hurt to de-solder and re-solder them.

But then, the PCB could be on the way out. If you get back there, take a look at the traces. If you remember that Blues Deluxe that had the meltdown (I posted pics), on the back some traces down the board looked corroded. But that could have been a result of the fire, too.

But I would like to get this sorted so I can concentrate on building something else for a while

I'm sure by now you know what my favorite Hot Rod mod is!

[yankeerob]

Uhhh... hmmmmmmmmmm - would that be - 'when is a hot rod a much hotter rod?' I'm dying to get cracking on that 6O100 now that I've got the bug - it appears to be an Orange design (hence the 'O' in the middle me presumes) - I'm gonna build it - then do a 1224 switch mod (1 tube A, 2 tubes A, 2 tubes A/B, 4 tubes A/B like on the Matamps) and then tweak the preamp to taste - it's amazing how much simpler the circuit is and I'm baffled as to why there's so much going on inside that Dv in terms of circuitry!!!

Regards present matters - I've had that many looks at the PCB (so many that I've finally stripped one of those crap PCB mounted jack sockets) and everything passes through the relay OK when it's powered down so tomorrow I'm gonna power it up and start fishing around the 16V supply routes & footswitch TP's to see what that turns up - it's a ball-ache but I've learned so much about this amp and amps in general that I could practically advertise myself as a HRDv specialist ..... butcher more like - but it's fun... most of the time.

Anyway - will keep you posted on tomorrow's expoits

[yankeerob]

Well - in case yer wondering what the state of play is - I'm tired of fighting with this damned PCB - and



I'm drawing the turret boards now!!

[NTBluesGuitar]

There ya' go! Now THAT is my favorite HRD mod!

What circuit are you going with? I've got some tips on components if you need...just e-mail me.

I'm in the middle of my second re-build now; both are 5E5-A with mid control and Copper Cap rectifier.

[yankeerob]

Yer gonna think I'm outta my tree - but I was thinkin' of flipping it and doing the whole damn HRDv point to point Only prob is three IC's are gonna be a bit tricky - I'd socket 'em anyway as well as the relays so I could get at 'em easy enough - the rest is not as bad as it looks...

I'm gonna do a Weber 5A40 or 80 soon enough anyway - thought I'd make use of the tranny's from the Dv - it was getting unmanagable - fix it - blow it up - fix it - blow it up shame is it sounded much better - read some stuff about upping the power cap values and how it can 'stiffen' the sound - which it did to some extent - thinkin' bout going back to 22uF's - BTW - those TAD caps are made by a German co. called F&T (Fischer & Tausche) - right badgin' buggers they are - TAD...

What turrets and boards are you using?

[NTBluesGuitar]

I've heard good things about F&Ts.

You can't do the HR thing PTP....I tried drawing the circuit out once, and it's just plain insane.

You can reuse all the iron from these in a classic circuit. Try the 5F6, it's pretty direct, the thing that I recently learned is that the choke affects bias...it's best to put the OT center tap on the B+ rather than after the choke.

Trust me, the iron sounds great when in the right circuit. You could easily work in the Weber 6A14HP too with just a rectifer socket hole and extra preamp tube hole. Otherwise, the 5E5/5E7/5F4 or 5F6 are just about drop-in.

Anything on the reverb side would get tricky. You'd need to turn the chassis 90-degrees and start punching holes.

I've really thought about all the options for the HRD re-builds, and doing anything other than the tweeds or 6A14 HP is really going to take some serious metal working.

Oh, I drill and press my own turret boards on G10. Keystone turrets ordered from Mouser.

Also, I discovered that Belton preamp and power tube sockets are best in these! No adapters necessary.

[yankeerob]

Hey good shout on the 6A14HP - you've worked out that I'm a bit of a reverb-head then - it just goes so well with the Tele... that'd fit with my jones for a cream/oxblood finish as well - nice one!

so the HR iron'll be OK in that then?

Oh yeah - what's G10?

[NTBluesGuitar]

The HR Iron worked great in the 5E5s I've done!

G10 is a military grade fiberglass-epoxy board that comes in various thicknesses and colors. Don't know if you can get it on that side of the pond...but I can't see why not. I get mine from McMaster-Carr (http://www.mcmaster.com and search for G10). It's heat and pressure resistant - I can lift the loaded chassis with iron by holding the mounted circuit board.

The DeVille Iron puts out some serious voltage, but if you follow the power supply schematics it ought to be just fine.

Not sure what the 6A14HP would need with that iron, but it's designed around the 2-6L6 tube complement. Also, the reverb tanks won't work since they're designed around the SS impedances.

Mounting a reverb transformer shouldn't be hard, tons of space on that chassis.

[yankeerob]

I'm sure the OT's gonna be fine - But my reservations about the PT are:

1. It hasn't got a 5V for the copper cap (though we might get around this later in point 3)
2. The filament taps are 3.26V though I expect that might be fine as that's what's heating them in the Dv so that's not as much of a concern...
3. As you mentioned - the Dv PT has a higher voltage output than the Dx PT - and - whereas the Dx PT only has CP15 & CP16 (two brown wires on the secondary side) feeding the bias (and a secondary 16V supply circuit) the Dv PT has a brown(CP15) and brown/yellow (CP16) feeding the bias and another brown (CP17) working with CP15 for the 16V supply... I suppose my CP15 and CP16 would be fine for the bias supply (I might just need to mod the bias circuit a little I suppose) and I might be able to find a way to use the CP17 tap for the copper cap (if I could source the right step down tranny). My only concern with that is the 6A14HP has a bias modulation type vibrato and I'm guessing higher voltages will affect it's operation.

As an aside - it turns out - upon further study of the schematic and my having marked all the spade connectors - that the Dv was wired for 230V operation - whereas the the mains voltage around here is always around 240 - I just measured 244 straight out of the wall and in the course of my travels have never measured less than 237 or so - anywhere in the UK. That would explain all the excess voltage in the power supply - I couldn't figure it - if you remember I kept mentioning that B+, X, Y & Z were all about 20V more than they should have been - no doubt at least part of the reason why this thing keeps giving up at high power

Well I'm gonna wire up the Dv PT properly and see what comes out of the other side - we might just skin this cat after all

BTW - thanks for the info on the G10 - looks like great turret board material!!! I can't wait to get cracking...

[yankeerob]

OK I was talking at least a little poo here but I'm comparing notes between the HRDv and Weber 6A14HP schematics & the published specs on the Weber W025130EU, a standard 041316 and what I can find on the HRDv PT's (there's not a lot to be found on the HRDv in the way of specs - I can only go on what I'm measuring)

This what I've found so far and am definitely going to need a little hand-holding

1. The filament tap (green wires) measures 7V so that'll be just fine - I'll just have to anchor it down to earth through 100R resistors (per the Weber schematic) as I haven't got a filament winding center tap to earth.

2. The main winding (red wires) measures 368V and hasn't got a center tap coming out of it - I know I'm being thick here but thats fine apart from being a little high? I just don't know what current I have as I can't find any specs on the Dv tranny and have no way of measuring it either...

3. What amounts to being the bias winding (brown wires) measures 58V with a measurement of 29V between the brown/yellow and either brown - so that's not a million miles away from the 50V spec of a 041316 though the W025130EU spec says it's is 45V - I suppose as far as bias circuit goes it's small potatoes and the bias circuit could be tweaked to accomodate the higher voltage if necessary but my concern is the vibrato in this regard.

4. That just leaves us with the 5V for the copper cap to figure out - I'm gonna have a trawl around for a 240 - 5V 3A transformer and see what I come up with. Weber do a stand-alone one but it'll no doubt be for 110-120V.

Any comments would be greatly appreciated

[JAM]

.

That just leaves us with the 5V for the copper cap to figure out - I'm gonna have a trawl around for a 240 - 5V 3A transformer and see what I come up with. Weber do a stand-alone one but it'll no doubt be for 110-120V

Copper caps dont have any filaments, so you dont have to add a 5V tranny. The problem is the lack of a center tap on the PT winding for the B+.

[NTBluesGuitar]

This what I've found so far and am definitely going to need a little hand-holding

1. The filament tap (green wires) measures 7V so that'll be just fine - I'll just have to anchor it down to earth through 100R resistors (per the Weber schematic) as I haven't got a filament winding center tap to earth.

Yup...I did it with two 100ohm resistors off the pilot light to a ring terminal at a PT bolt

3. What amounts to being the bias winding (brown wires) measures 58V with a measurement of 29V between the brown/yellow and either brown - so that's not a million miles away from the 50V spec of a 041316 though the W025130EU spec says it's is 45V - I suppose as far as bias circuit goes it's small potatoes and the bias circuit could be tweaked to accomodate the higher voltage if necessary but my concern is the vibrato in this regard.

That's new territory for me. I did a straight-up bias as it's drawn in the HRD schems. And it's US iron with just the brown windings.

2. The main winding (red wires) measures 368V and hasn't got a center tap coming out of it - I know I'm being thick here but thats fine apart from being a little high? I just don't know what current I have as I can't find any specs on the Dv tranny and have no way of measuring it either... That just leaves us with the 5V for the copper cap to figure out - I'm gonna have a trawl around for a 240 - 5V 3A transformer and see what I come up with. Weber do a stand-alone one but it'll no doubt be for 110-120V.

No need for 5V windings as JAM points out for the Copper Caps...that's what makes them so groovy for this kind of job. The workaround (that JAM helped me discover) for that involves two rectifer diodes and a ground connection off the copper cap tube socket. I can get my drawing of it for you...don't have it here at this time.

Can't see the details, but this is what it all looks like in mine:

[yankeerob]

.

Copper caps dont have any filaments, so you dont have to add a 5V tranny. The problem is the lack of a center tap on the PT winding for the B+.

OK - but neither does the Dx PT - so I expect NT can shed some light on this unless the 5A5 doesn't require a B+? This is all new to me - I've done some pretty amazing hi-spec prototypes in my time as a wireman - but an amp designer I'm not

[yankeerob]

That's new territory for me. I did a straight-up bias as it's drawn in the HRD schems. And it's US iron with just the brown windings.

No need for 5V windings as JAM points out for the Copper Caps...that's what makes them so groovy for this kind of job. The workaround (that JAM helped me discover) for that involves two rectifer diodes and a ground connection off the copper cap tube socket. I can get my drawing of it for you...don't have it here at this time.

No worries or hurries - The only difference between the US and export iron is the primaries - so however you did it on the secondary side will be of interest, particularly the bias as we'll hopefully find a workaround regards the vibrato - I'm at the planning stage as I've managed to scrounge a Peavey Reknown to get me by for gigging - it seems like everyone has one of those kicking around a closet or garage somewhere But yer - I'm really grateful to you guys for the help - my mate John (ex-BBC dude) has also phoned to say that he may be able to get one made for the job but I'd like to see if I can get by with the old iron first...

I'd also ideally like to add a mid control as well - I'm not asking much, eh? But I expect that'll just be an augmentation of the existing tone stack - I have to say this is exciting!!!!!

[NTBluesGuitar]

OK - but neither does the Dx PT - so I expect NT can shed some light on this unless the 5A5 doesn't require a B+?

Yeah, there's a B+, but what you measured may have been off depending on the current load your amp had on it when you measured? If in standby, the B+ is lower, if it's on, the B+ rises with the load needs.

On my amps, the B+ was affected by bias, too, but not as much if you put the OT CT on the B+ at the first filter cap instead of after the choke like in the tweeds. But then, I hadn't messed with a DeVille yet. Just a Blues and Hot Rod Deluxe so far.

You can add a Mid Control to the 5E5/5F4/5E7 easy enough...never looked at it in the 6A14HP, though.

*Edit: I see what you're referring to when talking about with the B+ when measuring 368V, that's about what I measure on standby with the Blues/Hot Rod Deluxes, it jumps up to 412V when there's a fixed bias load, and right at 400V with the cathode biased load (with 400ohms cathode resistance; yeah, my cathode bias is also adjustable )

[JAM]

You can get a copper cap module from Weber that works with full wave bridge circuit like the HRDx. Also, you can specify the amount of voltage drop you want. A better solution, IMO. NTBG had already mounted the copper cap and tube socket, so we worked on and found a workaround. Or you could just build a FWB with SS diodes.

[NTBluesGuitar]

Good points, JAM, as always.

I had a silly hang-up with something that resembles a tube rectifier under the chassis.

Oh, BTW, here's my most revised bias circuit layout for the HRDlx (there's the C- electrolytic cap to ground on a switch that's not pictured)...it's built out just as the schematic calls for and puts out the right amount of negative voltage:



It's also a good look at what the G10 epoxy looks like.

[JAM]

Looks nice! I really like the turret boards.

[yankeerob]

Right - just so everyone's on the same page - heres the HRDx supply:


and heres the deville:


I'm sure with a bit of tweaking we could get this right - 'cause essentially all they've done to achieve 60W* out of the 40W design is beef up the supply voltages and use a OT to suit - it'd be a riot if we could do the same in the 6A14HP - iI just don't have the design know-how to do it

Good ole Stan, eh? His face speaks a thousand words....

Aw, man.... just saw yer post - that is just stunning - I mean - that is definitely worth aspiring to!!!!!!!!!!!!!!!

*John measured over 70 filthy watts - it's little wonder - damned thing was set up wrong from the factory!

[NTBluesGuitar]

It looks like the DeVille's bias AC feed is lower than the Deluxe's. There's a lot of junk in the footswitching that you'll be ignoring, too. The bias layout for the DeVille would need to be re-drawn, I gather. There's a few extra components in there that the Deluxe doesn't have, but I wonder if it couldn't be streamlined for the more direct approach you'd be needing.

The power supply doesn't seem too weird. The typical series-wired caps for higher voltages. There's definitely room in the chassis for the extra components.

Looks nice! I really like the turret boards.

Me too!

The more I use them, the more I like them. You can stack wires on the floor and components on the tops of the turrets resulting in having none of the jumpers on the back.

The latest board I did was mounted empty in the chassis and I populated/wired it in the chassis after the sockets and such were ready.

[yankeerob]

Boy it's learn as you go 'round here - I'm starting to get it - and as another addendum to the dead Dv - I had to replace all of those 220K's on the B+ and Z rails as the over-voltage supply courtesy of our friends in Corona setting it up for 230V had started to fry 'em - put some good quality 5%'ers in and the problem just moved elsewhere...

Right - the readings I took - on the last post about voltages - were with the tranny out of circuit & plugged straight into the wall and with the correct config on the primaries (you have to join the black/green & black/yellow - the white, white/black & black/red are just left OC, violet is line, black is neutral for an export tranny running at 240V) - the meter I used isn't a world beater - it's a Fluke Model 12 - you could do a lot worse - done me proud over the 10+ yrs it's been in the tool bag

[yankeerob]

Looks nice! I really like the turret boards.

Dude - you're starting a whole new fashion trend - forget Project Catwalk (which I only admit t knowing about because if you knew my you'd understand) - but that really is kick-*ss stuff!!!

You're defiinitely heading for the TFF HOF!!!!!!!

[yankeerob]

It looks like the DeVille's bias AC feed is lower than the Deluxe's. There's a lot of junk in the footswitching that you'll be ignoring, too. The bias layout for the DeVille would need to be re-drawn, I gather. There's a few extra components in there that the Deluxe doesn't have, but I wonder if it couldn't be streamlined for the more direct approach you'd be needing.

The power supply doesn't seem too weird. The typical series-wired caps for higher voltages. There's definitely room in the chassis for the extra components...

Yessireebob - there is now - I know we're breaking new ground here what with it being a little bit more complicated and all - but I'm confident that all they did was take a HRDx and say 'how are we gonna sqeeze a bit more power out out of it' - I don't know enough about design to say why they chose the route they did - but like you say we haven't got all that channel switching to deal with and the power supply and OT are the only deviations between the Dx & Dv - I'm willing to run the thing up using what we have and what we know from NTBG's experience with the Dx iron and see how much smoke we produce I'm a big Thomas Edison fan - my great gran (who lived to 105 - gone now sad to say) worked for him - she said his overall was always dirty and the only time he changed it was when there were so many holes in it that it was ineffectual and that's me to the left - took every damned toy I ever got apart to see how it worked...

If I knew enough about it I'd work it out - but I don't - I'm reading all I can about it - but - all I can say is big, big thanks to you all - and LET'S GO FOR IT!

[JAM]

yankeerob,

The bias supply on these come from a separate winding, not a tap like most typical Fender trannys. Ignore all the stuff that the HRD has coming off for the +/-16V supply - you dont need any of it. (Dont need the voltage doubler on half the winding for the bias either if using the whole winding)

On the schematic for the HRDvl, does CP16 connect to a CT on that winding that's not shown? Is that the brown/yellow you mention in a prior post? (I think there's an error in the drawing)

{edit}Checked the schematic for the Blues Deville (the same PT) and it does have a CT on the Bias winding.

[refriedwhiskey]

That turret board shot really does look fantastic. So clean and squared away. Do you do less soldering that way?

[JAM]

Do you do less soldering that way?

No, it's just an alternative to the old Fender style eyelets.

[yankeerob]

yankeerob,

The bias supply on these come from a separate winding, not a tap like most typical Fender trannys. Ignore all the stuff that the HRD has coming off for the +/-16V supply - you dont need any of it. (Dont need the voltage doubler on half the winding for the bias either if using the whole winding).

I can confirm that - put a meter on all the windings to test for DC resistance and they're all separate circuits... also measured 58V between brown & brown and 29V between brown/yellow and either brown... that was with the tranny just plugged straight into the wall with no load...

On the schematic for the HRDvl, does CP16 connect to a CT on that winding that's not shown? Is that the brown/yellow you mention in a prior post? (I think there's an error in the drawing).

Yer - the brown/yellow wire went to CP16 whose first port of call is CR10 as per drawing... the drawing doesn't confirm that it's the CT but the evidence suggests it is

{edit}Checked the schematic for the Blues Deville (the same PT) and it does have a CT on the Bias winding.

I'm assuming that's a good thing?

[yankeerob]

I've come up with a slightly different idea - having had a look at the tweed circuits I think we could take a 5E7M - add the presence control a la 5E7 - that's gonna give me the more of the sound I'm after and I suspect the 6A14 tone stack is gonna be a pain to get the mid and presence controls into - both of which I've become accustomed to with the HRDv. I may have to do without an integrated reverb (though I'm studying the 5A40 drawing to see if I can fathom how we might be able to get it in) and I'm not that bothered about vibrato anyway. I've been using a TC Electronics G# rack thing in the effects loop of the HRDv for that and I prefer it to the bias modulating type anyway. I'd like to get a send/return in the circuit somehow but if it can't be done so be it - the TC is very user friendly in that it least modifies the tone of an amp out of anything I've ever used - but it's not a necessity.

But I think a more straight forward approach with a tweed circuit is gonna lessen the possible headaches of this project - we won't have the vibrato to complicate the bias circuit - if we can get a reverb circuit in - fine - if not - oh well and I suspect the send/return's not going to be rocket science.

Whatcha think?

Here's the modded 5E7M schematic which I've added the presence control from the 5E7 to...

http://images.lilypix.com/albums/use...mal_5E7M-P.jpg

[NTBluesGuitar]

That turret board shot really does look fantastic. So clean and squared away. Do you do less soldering that way?

As JAM says, they really don't cut down on soldering.

There are other benefits that I like, though. Especially in regards to component stacking. For example, on preamp tubes' cathode bias stuff, you can put the resistor on top the turret in the tubes, while wrapping the caps leads around the shaft. It allows you to go vertical instead of horizontal. Here:

I know we're breaking new ground here what with it being a little bit more complicated and all - but I'm confident that all they did was take a HRDx and say 'how are we gonna sqeeze a bit more power out out of it' - I'm willing to run the thing up using what we have and what we know from NTBG's experience with the Dx iron and see how much smoke we produce

- all I can say is big, big thanks to you all - and LET'S GO FOR IT!

Lets!

Anyway, I don't think it's really a "Let's take a HRDlx and squeeze power out it" type of thing. More like "lets take this same circuit and make a 2x12 or 4x10 out of it.

I think that the bias differences can be settled rather simply. Once that's worked out, I can't see why it would be any different that what I've done with Blues and Hot Rod Deluxes. Just build out the first two stages' filter caps like the schematics call for and plug in the B+ rail resistors from your circuit of choice.

I've been really wanting to try making a 5F6 (Tweed Bassman) out of a Deville if I could get my hands on one for parts.

JAM definitely has you headed in the right direction. He knows a pantload more about interpreting schematics than I do.

[yankeerob]

You're on!!! We should be able to get the basic amp off the ground with a minimum of fuss - I like reverb - not great big shower room wash - just a touch to give it a bit of life - something I think Fender have gotten right - if I have to build an external unit - fine - but I'd like to squeeze it in if poss - back to the drawings....

[NTBluesGuitar]

Not sure about re-using the existing reverb...it's designed around the SS components. But, sounds like you have experience in that, you may have a way to integrate the SS reverb circuit into the rest of the circuit?

[yankeerob]

No - I was gonna ditch the SS reverb altogether as it doesn't really go with the tweed vibe - was thinking along the lines of seeing how they put the reverb in on a 5A40 and seeing if there was anyway of augmenting the 5E7 with that - always thinking

[JAM]

For a HRDx to 5Ex Tweed rebuild dont even consider adding reverb. Not worth the hassle IMO. When I still had my '59 RI I never missed it. Keep the circuit as simple as possible.

[ziess]

Why not put a Weber Add-a-Verb in the bottom of the cabinet? Or, better yet, just build a 5H15, they're not too dear.

[yankeerob]

OK Jam - I'll run with that - so all we have to do now is work out the power supply and we're away -

I've added a presence control to the 5E7M by having a look at the 5E7 and came up with:

http://images.lilypix.com/albums/use...379/5E7M-P.jpg

Wondered if you'd mind having a look at it to see if it's kosher? Oh yeah - almost forgot - what about the send/return idea?

Thanks for that Ziess - gonna have a look at it...

Thanks guys!

[NTBluesGuitar]

The 5E7M with Presence is the tone stack I put in mine (well I put in in a 5E5, but that's just a couple resistors' difference). It's pretty simple to do...but honestly, there isn't a whole lot the Mid control does compared with the rest.

[JAM]

yankeerob,

Here's how I'd do it:

http://members.canonphotogroup.com/j...7m_schemYR.JPG

One issue that NTBG and I 'discovered'; the choke on the 5E7/5F4/5E5A, has a larger current rating (the plate current is going through it too). If you compare the schematics you can see the placement of the choke in these amps is before the OT CT, while later amps like the 5F6A Bassman have it after. The choke on the HRD amps is more like the Bassman version. I havent looked into the send/return, but I don't think you need it on these amps.

The schem I modified of course, doesnt have the actual PS drawn for the conversion. As I see it, there's three issues (at least). First, the B+ winding on the HRD does not have a center tap. Second, the bias is derived from it's own winding, so an appropriate voltage divider and bias pot will have to be added. Third, the choke issue I mention above, if you want to keep the circuit closer to the actual 5E7 with the choke first, I'd upgrade the choke to a Weber W014684.

[NTBluesGuitar]

JAM, have you ever tried the 470ohm screens in a non-Bassman Tweed? I'm wondering what they'd do?

Not like it would be hard to add them...

[JAM]

JAM, have you ever tried the 470ohm screens in a non-Bassman Tweed? I'm wondering what they'd do?

Not like it would be hard to add them...

No, I'm wondering too. But I don't think it would have a major impact on the sound.