Blackheart 5 Watt Conversion to Hoffman Stout

[purpletele]

I was contemplating what format to build the Hoffman Stout and I saw a Craig's listing for a 5 Watt Blackheart for $100.  A nice cabinet with a great chassis with a perfect control panel for the Hoffman Stout or a number of different options.

I may be late to the game but this is a ridiculous product for $100.  It sounded great with nice speakers to begin with, but then I cut it loose to get to the chassis!

I just received parts for the Stout over the last two days and then this frame came up so I think I have a project ready to build itself.

It happens to be a good solution for a gift for a Gal friend guitarist if I can get it together.

I have enclosed photos.  Please comment on the layout of the transformers.

Is this common knowledge, this seems like a nice cabinet for obsessed builders.

[pompeiisneaks]

Looks like it should be great, is there something fundamentally bad about the tonality of the Blackheart 5?  Ultimately, I think being able to get the chassis and transformers for that cheap alone is worth it anyway :)

~Phil

[sluckey]

What are the dimensions of that chassis and PT? Also, notice that Hoffman's new stout board layout is set up for the tubes to be placed on the front panel side of the chassis.

[purpletele]

Looks like it should be great, is there something fundamentally bad about the tonality of the Blackheart 5?  Ultimately, I think being able to get the chassis and transformers for that cheap alone is worth it anyway :)

~Phil

Phil,

Like the rest of you project guys I am always looking to re-purpose equipment.  The Blackheart chassis and cabinet is ridiculously nice, especially for $100.

The Blackheart 5, when connected to a nice speaker, actually sounds pretty good.  David Allen has a cool Point to Point retro kit for it as well

However, I have parts for a Stout so the PCB went to the way side.  I'll try the retro rebuild on another occasion.

[purpletele]

What are the dimensions of that chassis and PT? Also, notice that Hoffman's new stout board layout is set up for the tubes to be placed on the front panel side of the chassis.

Steve,

The dimensions are 13 3/8" long x 7 3/16 wide x 2 1/4"

The PT is 3 3/4" x 3 1/8"

I am trying to find the best arrangement for the board and tubes since I have to drill out everything.  I am not too concerned about a little remodeling of the layout.  I don't think I will find anything really unmanageable.

Let me know if that is taboo, if so then my 6 v 6 19 watt Plexi is going to hell! That was a complete twisted remodel of the physical layout.

Thanks,

BV

[pompeiisneaks]

Looks like it should be great, is there something fundamentally bad about the tonality of the Blackheart 5?  Ultimately, I think being able to get the chassis and transformers for that cheap alone is worth it anyway :)

~Phil

Phil,

Like the rest of you project guys I am always looking to re-purpose equipment.  The Blackheart chassis and cabinet is ridiculously nice, especially for $100.

The Blackheart 5, when connected to a nice speaker, actually sounds pretty good.  David Allen has a cool Point to Point retro kit for it as well

However, I have parts for a Stout so the PCB went to the way side.  I'll try the retro rebuild on another occasion.

Cool, was just curious.  It's a great price in my opinion for the basic hardware alone as mentioned.  Yup if it all fits, that may be a fun project to try some time!

~Phil

[sluckey]

I would try to arrange the chassis kinda like this...

[purpletele]

I would try to arrange the chassis kinda like this...

Steve,

Thank you for you advice and sketch, I like that program more and more.  I think I am seeing the pitfalls of layout better now.  I had it laid out last night as shown in the photo.

1.  I like the position where you have the Cap Can.  I am looking for a solution to punch a 1 1/2" hole through this steel chassis.

2.  The location where you have the Cap Can shown is pretty tight.  Will I create interference with the Cap Can placed in between the board and xfmr if I have to relocate it to that location?

BV

[kagliostro]

Put a 1.5mm aluminium sheet on the top of the steel chassis

this way you have a flat surface without holes and can arrange the new layout as you prefer

Franco

[sluckey]

Will I create interference with the Cap Can placed in between the board and xfmr if I have to relocate it to that location?

That'll be fine.

[purpletele]

Here are some progress photos of the tube placement.

I ended up using the symmetry of two existing holes which required that I tuck the rectifier socket back behind the xfmr.  Let me know if the placement of that rectifier socket will cause an issue, I think it works out ok.   This chassis is 16 Ga steel, it is tough to work with if you don't have the right tools.  I am ordering a few new tools, an 1 1/2" punch for starters.

Everything else seems to layout fine.  Good progress!

[macula56]

Blackhearts are great amps in general. I converted one of the 15 watt amps into a 50 watt plexi and kept one stock. I really prefer the stock sounding one more than the plexi. It's a great little circuit.

[purpletele]

Hoffman Stout Progress Photos

The chassis is a SOB to modify holes and such unless you have the right tools for heavy gauge steel.

All in all, it is coming together quite well.

BV

[purpletele]

Blackheart Conversion Update

Great progress, pretty quiet engine so far.  Started up well with some issues around the treble POT.  I know I can take care of those issues with some minor rework.

Good voltages throughout.   I am hoping to have another work horse for a stereo rig.

[tubenit]

Very well done! Thank you for sharing!  Looks great.


With respect,  Tubenit

[purpletele]

Very well done! Thank you for sharing!  Looks great.


With respect,  Tubenit

Thank you!

I found that control wires don't want to be any where near the OT wires.  I made a couple of tweaks with my lead dress and Sherman responded favorably.  This thing is a beast!  It sounds really nice, my first imprecision was DOD, Dirt on Demand.

I have installed some low gain Russian EL 84's and I am looking at some other ideas to give it just a little more clean headroom if possible. 

That was a nice project for me, the majority of the work was in the chassis work. 

Here are the completed photos from a couple of hours ago.  I will make some videos or sound clips.

[PRR]

> control wires don't want to be any where near the OT wires

This should be burned into everybody's workbench.

Actually of course the wires are perfectly happy picking up the huge OT swings and causing squeals, but the user may not be pleased.

[purpletele]

The purpose of building the Hoffman Stout TMB was to construct a very strong and simple 18 watt amp that serves as a great back up amp as well as a clean experiment platform.

The amp sounds really nice as originally designed, I was pleased with the initial outcome.  I went on to voice the amp through tube types.  I put an NOS 5751 in V1 and that really smoothed things out from a little bit of cold harshness.

JoJokeo suggested an AT7 in V2 which seemed to really enhance the articulation and touch, but somehow when rolling the tube I literally tossed it a few feet trying to pull it out.  So I now have two 5751 tubes in the pre amp section, and it is quite nice. 

I was pleased to see the thread on the other Stout that went through the voicing.  I went through and added the components as recommended by Tubenit and his modified Schematic.  The amp responded to the mods favorably.  Very nice singing tone, gritty with humbuckers. 

This amp is turning into a really strong and useful piece of equipment.  The amp is really strong and loud just a touch past zero.  If you roll the volume up to 9:00 it is blowing the walls out.

I will check and post voltages later today. I really want to work through the PPIMV configuration.  I think that will really make this amp a great tool. 

I have used the PDF files that Tubenit had posted in the other recent Stout thread, but I did not see a layout of the PPIMV.  It might be on the layout file with a .sch extention. 

  a.  I don't have the program currently loaded to open those files.  Does anyone have a layout of the PPIMV wiring for the stout?  That would be very much appreciated, I feel like that amp has the potential to      sing at a controlled lower volume. 

I am going to work on modifying my As-Built values on the Hoffman Schematic including a voltage comparison, so that should be real helpful.

I appreciate any info or advice on the PPIMV, I have the Pot mounted and I am gathering info to wiring it this weekend.

Brian v

[sluckey]

...

[purpletele]

...

Steve,

That is magical! 

Thank you!

[purpletele]

Well it has been a nice day in California and its been a successful Stout Modification Day.

Sluckey, the PPIMV works wonderfully, that made my day!

Tubenit, thanks for the work on the Mod Drawings.

I think that all of the Mods that I did to this amp have turned it into a very toneful and useful amp.  With the Master Volume and volume EQ it to can get singing tones and harmonics at a low volume just as I had imagined.  You can adjust it to be loud and chimey as well.

The voltages were all stable and consistent with Doug's prototype, so I am pleased with that as well. 

I certainly appreciate all of the information and help that all of you guys provide.  I think that this amp is way ahead of schedule and it is ready to hit the circuit, as a back up.

Very satisfied with the project! 

BV

[jamaio]

Looks good!!

I will have to add all these mods to my Stout Reverb. I will probably add the mods after I get the original design built.

Hopefully mine will look and preform as good as yours.

What speaker did you use?

[purpletele]

Looks good!!

I will have to add all these mods to my Stout Reverb. I will probably add the mods after I get the original design built.

Hopefully mine will look and preform as good as yours.

What speaker did you use?

I tried the amp with all of my speakers cabs and they all sounded nice.

1.  I have a Mojotone Blues Jr. extension cab with a Eminence Z-12.  Sounded great so my pal took it and played live and it did not disappoint.
2.  I also have an Eminence GA-SC64, actually two of them in different 1 x 12 cabinets by Mather.  Those are sleeper speakers for $100, the Z-12 included.
3.  I also played Sherman through my 2 x12 closed back slant.  That has a C gold and C cream.  A lawnmower sounds good through that set.
4.  I have a Cannabis Rex in another Blues Jr. Extension cab.  That sounded great as well.  Very American sounding.

Great plan to follow the plan when available!  That is what I did to establish a strong baseline.

The mods are very easy.  I had the chance to see and hear it performed with a band and it sounded fantastic.  The comment after the show from Adam the player was that the amp was very articulate and touch sensitive, he had a blast with it and it performed.

I literally finished the PPIMV a couple hours before the show.  We had other options, but it really worked well, so we went with it.

Looking forward to a report.

[jamaio]

I literally finished the PPIMV a couple hours before the show.

What pot did you use? And are the resistors 2.2M?

Thanks,

[purpletele]

I literally finished the PPIMV a couple hours before the show.

What pot did you use? And are the resistors 2.2M?

Thanks,

The pot is 250K Dual Gang and the resistors are 2.2 M.

I attached the detail that Sluckey provided on the PPIMV and the mods Tubenit provided as well.

[jamaio]

The pot is 250K Dual Gang and the resistors are 2.2 M.
I attached the detail that Sluckey provided on the PPIMV and the mods Tubenit provided as well.

Thanks!!

[purpletele]

Steve,

I am going to try 6 v 6's in my Stout.

How did you cut the detail so quickly when you showed me the PPIMV?  I want to redraw this detail for the 6 v 6's. 

I haven't come across a cut and paste function in Visio although I am sure its there.

Thanks,

BV

[sluckey]

Most of the work was done with Paint Shop Pro. While viewing Hoffman's Stout pdf I zoomed in on the power amp end of the board. Then hit print screen to dump the visible screen to the clipboard. Next I pasted the clipboard contents into PSP as a new image, did a little editing to get rid of stuff that was not important to see. Saved as a png file.

Now open Visio, new sheet, and insert image. Choose the one I just saved. Resize the image in Visio until the size of the tube sockets is 3/4" diameter. Then drop a dual pot shape and two 2.2M resistor shapes on the page. Add lines to connect the pot to the pertinent places on the pic, ie, board and tube sockets.

Finally, I did another print screen of the Visio page, dumped it into PSP as a new image, cropped the image and saved as a png file. Uploaded the png file to the forum.

I never even saved the Visio file. 

[purpletele]

Most of the work was done with Paint Shop Pro. While viewing Hoffman's Stout pdf I zoomed in on the power amp end of the board. Then hit print screen to dump the visible screen to the clipboard. Next I pasted the clipboard contents into PSP as a new image, did a little editing to get rid of stuff that was not important to see. Saved as a png file.

Now open Visio, new sheet, and insert image. Choose the one I just saved. Resize the image in Visio until the size of the tube sockets is 3/4" diameter. Then drop a dual pot shape and two 2.2M resistor shapes on the page. Add lines to connect the pot to the pertinent places on the pic, ie, board and tube sockets.

Finally, I did another print screen of the Visio page, dumped it into PSP as a new image, cropped the image and saved as a png file. Uploaded the png file to the forum.

I never even saved the Visio file.

Thanks, I suspected it was a cut and paste operation, you seem to be quite efficient at it.

I'll play with it a while, I have some questions so I'll see if I can develop a similar detail.

[purpletele]

Most of the work was done with Paint Shop Pro. While viewing Hoffman's Stout pdf I zoomed in on the power amp end of the board. Then hit print screen to dump the visible screen to the clipboard. Next I pasted the clipboard contents into PSP as a new image, did a little editing to get rid of stuff that was not important to see. Saved as a png file.

Now open Visio, new sheet, and insert image. Choose the one I just saved. Resize the image in Visio until the size of the tube sockets is 3/4" diameter. Then drop a dual pot shape and two 2.2M resistor shapes on the page. Add lines to connect the pot to the pertinent places on the pic, ie, board and tube sockets.

Finally, I did another print screen of the Visio page, dumped it into PSP as a new image, cropped the image and saved as a png file. Uploaded the png file to the forum.

I never even saved the Visio file.

As anticipated there are some tricks to your swift editing technique.  I used MS Paint, not so effective but enough to get the point across.


Something doesn't look right with my configuration that i put together.  Can I get a ruling on my configuration that I put together?

Thank you,

BV

[sluckey]

Something doesn't look right with my configuration that i put together.  Can I get a ruling on my configuration that I put together?

You made a bomb! The red wires from the board should go to pin 4 on the sockets and the green wires from the pots should go to pin 1 on the sockets. Remove the 470Ω screen resistors from the sockets. The 1Ks on the board are the screen resistors.

The 2.2M resistors should connect between the left and middle pot lugs.

The 130Ω cathode resistor should be 250Ω for 6V6s.

Doug has the Visio file for his projects. He might give it to you. That would simplify your mods. Send him a pm and ask. Can't hurt.

[purpletele]

Something doesn't look right with my configuration that i put together.  Can I get a ruling on my configuration that I put together?

You made a bomb! The red wires from the board should go to pin 4 on the sockets and the green wires from the pots should go to pin 1 on the sockets. Remove the 470Ω screen resistors from the sockets. The 1Ks on the board are the screen resistors.

The 2.2M resistors should connect between the left and middle pot lugs.

The 130Ω cathode resistor should be 250Ω for 6V6s.

Doug has the Visio file for his projects. He might give it to you. That would simplify your mods. Send him a pm and ask. Can't hurt.

It does look like its ready to detonate!

Thanks Steve

[purpletele]

Something doesn't look right with my configuration that i put together.  Can I get a ruling on my configuration that I put together?

You made a bomb! The red wires from the board should go to pin 4 on the sockets and the green wires from the pots should go to pin 1 on the sockets. Remove the 470Ω screen resistors from the sockets. The 1Ks on the board are the screen resistors.

The 2.2M resistors should connect between the left and middle pot lugs.

The 130Ω cathode resistor should be 250Ω for 6V6s.

Doug has the Visio file for his projects. He might give it to you. That would simplify your mods. Send him a pm and ask. Can't hurt.

Getting back to Sherman and the 6 v 6 conversion.  I have been studying and reviewing different schematics. I was referencing the 18 Watt Plexi, I think I should be utilizing the standard detail similar to the 5 e 3.

Can I ask for some advice and verify that my hacked up drawing is the proper configuration for this conversion?

Mucho Appreciated.

[sluckey]

 

[purpletele]

I have made the adjustments to the 6 v 6 socket wiring, but I am not getting any voltage on Pin 5/6

I had the PPIMV hooked up and working efficiently with the EL 84's and haven't modified anything else other than the tube sockets.

I have posted my voltages.

I am not getting any signal through, no sound. 

I had a very microphonic tube in V1 yesterday and replaced it, so that threw another variable at the issue.  If logic holds true I might still have a tube issue.

Any advice is very much welcome.  Temporarily stumped, which seems to happen quite often in Tube Amp Land.

[shooter]

I am not getting any voltage on Pin 5/6

If I looked at the pinout correctly pin 6 is not used and pin 5 is grid1.

[purpletele]

I am not getting any voltage on Pin 5/6

If I looked at the pinout correctly pin 6 is not used and pin 5 is grid1.

So I shouldn't expect any voltage on the 5/6 pin config? Or are you indicating that it is wired incorrectly?

thanks,

BV

[sluckey]

Pin 5/6 should read zero volts.

[sluckey]

V1 pin 7 and 8 voltages are wrong. Pin 7 should be zero and pin 8 should be about 2V. Look at Hoffman's schematic. The proper voltages are on it.

I don't suspect a tube as your problem. I suspect a wiring error. Did this amp ever work properly?

[purpletele]

V1 pin 7 and 8 voltages are wrong. Pin 7 should be zero and pin 8 should be about 2V. Look at Hoffman's schematic. The proper voltages are on it.

I don't suspect a tube as your problem. I suspect a wiring error. Did this amp ever work properly?

I'll check the voltages again, might have been a transposition error.

The amp was working quite nicely with the el 84's.

I have it up and running with good response but it doesn't sound that great, not bad at all but not that musical.

The low strings feel real spongy and flabby. 

If my voltages look right then I'll start looking for voicing tips to tighten it up.


Update:  I cleaned up my voltage chart and all voltages are consistent with the Hoffman Schematic. 

It's now a voicing project.

Thanks for the council.

[shooter]

It's now a voicing project.

I'd have to dig up notes, but 6V6 will need more drive to get the same results as 84's

[purpletele]

It's now a voicing project.

I'd have to dig up notes, but 6V6 will need more drive to get the same results as 84's

When you say drive does that mean bias voltage?

I remember having a small 3.6 V transformer for a Blues Junior that I had converted to 6 V 6's

I am not thoroughly fluent with voltage requirement differences and how to compensate, at least not yet.

It feels like it might lack some Drive

[shooter]

When you say drive does that mean bias voltage?

I mean the voltage swing into the grid of your power tubes.  say 8vAC got the 84's all hot n bothered, you will need something like 12Vac to do the same on the 6V6.

I use the bias "value" as a starting point for how much drive I need.  my current project is biased at 34v.  I want a signal > 34v to get the pwr tube to distort.  I'm a SE guy so the "rules" are a little different in PP since it's AB biased vs closer to class A biased

[purpletele]

Sounds like I need to break out the booster transformer.

This will be interesting

[shooter]

This will be interesting

maybe try some easy things 1st
disconnect the NFB... right direction or wrong
where's your bias set?  have you tweaked while playing?... right direction or wrong?
try at least 2 different cabs........

then hack

[purpletele]

This will be interesting

maybe try some easy things 1st
disconnect the NFB... right direction or wrong
where's your bias set?  have you tweaked while playing?... right direction or wrong?
try at least 2 different cabs........

then hack

Shooter great suggestions.

1. First of all I am glad I am in this equation, I needed to learn and understand the variables of manipulating bias voltage.

2. I have not set the bias.  Now that it is connected and running I can back into the bias and voicing.

3. Disconnecting the NFB made a nice boost in Power and Signal to the point of what I feel is pretty close to an operating level but it is still on the cold side.  Thanks for the tip.

4. I have tried different cabs, but this is definitely and engine running a little cold.

5. I need to do some homework to get the bias set. 

6. The Master Volume that I installed needs to be cranked to 90% for the tubes to sound good.  So the Master is ineffective as an EQ tool without more voltage or correct bias.

The amp was quite pleasant to play, in fact it is very close to what I had imagined it to feel and sound.

It is definitely very powerful and the tone is getting really nice.

Any further input is welcome.

Thanks

BV

[sluckey]

So you went from "no sound" at noon to "very powerful and the tone is getting really nice" tonight. What did you do?

You need more signal voltage coming from the PI to drive 6V6s. This is not something a "booster transformer" (whatever that is) can do. Change these two resistors and see if it gets louder. see pic...

[purpletele]

So you went from "no sound" at noon to "very powerful and the tone is getting really nice" tonight. What did you do?

You need more signal voltage coming from the PI to drive 6V6s. This is not something a "booster transformer" (whatever that is) can do. Change these two resistors and see if it gets louder. see pic...

Once I had determined everything was wired correctly I went over all of the critical connections and re-flowed them.  Then I changed the two pre-amp tubes just to eliminate that question.  Unfortunately, that shotgun approach didn't isolate the culprit, but it is running at full capacity now.

Shooter recommended that I disconnect the NFB which I did, and that is where the boost of power is coming from.  It's almost very musical at this point, nice but not quite there.

I'll implement your recommendations and then re-connect the NFB and see where it's at.

I am paying the price for playing with electronics all day.  I have to actually work tonight to make up for Circuit Fog today.



I see your photo with the notes, thank you!   

[purpletele]

So you went from "no sound" at noon to "very powerful and the tone is getting really nice" tonight. What did you do?

You need more signal voltage coming from the PI to drive 6V6s. This is not something a "booster transformer" (whatever that is) can do. Change these two resistors and see if it gets louder. see pic...

Well the PI resistor mod worked very well!  The amp is starting to tighten up and being more responsive.  I hooked up the NFB and the signal and tone was getting quite a bit closer. 

I'll take any other suggestions, otherwise I am going to experiment with the caps including reducing the bass and middle cap to .045 in lieu of .022. 

I currently have the 47 uF 100V Cathode By Pass Cap in place.  Should that be adjusted to a larger value?

[sluckey]

Changing those two resistors gave the PI a little more gain. Those values were borrowed from Hoffman's Plexi 6V6. If you want to make the PI look exactly like the Plexi 6V6 then make ***ALL*** the changes in the attached pic. At that point, you will have a cathode biased Plexi 6V6 which should sound pretty darned good.