I am interested in what the point of this exercise is, or how it is relevant to the BH EL34, which is already a very cumbersome thread for builders of the existing PCB?
There exist PCB designs for this circuit, tried and tested in multiple builds, refined over a few revisions. Wouldn't it be more fulfilling to design a PCB for another design? I would be interested in reading your trials and tribulations for that on a dedicated thread.
There exist PCB designs for this circuit, tried and tested in multiple builds, refined over a few revisions. Wouldn't it be more fulfilling to design a PCB for another design? I would be interested in reading your trials and tribulations for that on a dedicated thread.
Hi OldHector,
I guess that's the catch. A build caught my eye so I thought well why not.
I'm open to suggestions, I'm learning as I go. So let's call me design agnostic if there is a term like that, but, putting it down to experience.
Which would be a good (recommended) design or designs to pick and go from there?
Happy to hear further suggestions and move this to a separate thread.
Thank you for your thoughts.
Earl Josh
I guess that's the catch. A build caught my eye so I thought well why not.
I'm open to suggestions, I'm learning as I go. So let's call me design agnostic if there is a term like that, but, putting it down to experience.
Which would be a good (recommended) design or designs to pick and go from there?
Happy to hear further suggestions and move this to a separate thread.
Thank you for your thoughts.
Earl Josh
Hi Earl Josh,
I'm sure most of the classic designs have been tackled, now that it is so convenient to get hold of high quality PCBs from web-based suppliers.
If I was doing this, I'd be looking at the good NOS tubes, that are still cheap, and developing a solution to enable people to get some boards, and experiment with tubes. That is essentially what George at Tubelab is doing with the new Unset project.
Going down that route, it becomes awkward to hard map pins of the tube to a pattern on the PCB, so I think it would be interesting to have a solution where the PCB has pads and a hole, or is fitted vertically, so that it can be fixed to the socket, which is screwed to the top plate, and different heater voltages can be incorporated.
Also, there are useful bolt-ons, like the tube current protection circuit that was promoted on Patrick Turner's site. If there was a simple PCB so I build that, with relays and LCDs, then I'd buy that. (The alternative being using stripboard, which does end up looking like stripboard).
Anyway, this is the thread for BH builders, using the PCB's designed by Marc, so this is off topic here.
Cheers, Richard
I'm sure most of the classic designs have been tackled, now that it is so convenient to get hold of high quality PCBs from web-based suppliers.
If I was doing this, I'd be looking at the good NOS tubes, that are still cheap, and developing a solution to enable people to get some boards, and experiment with tubes. That is essentially what George at Tubelab is doing with the new Unset project.
Going down that route, it becomes awkward to hard map pins of the tube to a pattern on the PCB, so I think it would be interesting to have a solution where the PCB has pads and a hole, or is fitted vertically, so that it can be fixed to the socket, which is screwed to the top plate, and different heater voltages can be incorporated.
Also, there are useful bolt-ons, like the tube current protection circuit that was promoted on Patrick Turner's site. If there was a simple PCB so I build that, with relays and LCDs, then I'd buy that. (The alternative being using stripboard, which does end up looking like stripboard).
Anyway, this is the thread for BH builders, using the PCB's designed by Marc, so this is off topic here.
Cheers, Richard
No joke. I have some of the boards where you have to do the mod for over-current protection (post #738). I haven't built mine yet due to many reasons, but with the new revisions and sidetracked discussions of different tubes, etc...I doubt they ever will be because this thread is so long and hard to follow as it is.
Yes the design is mature but with the boards as they are now they leave the builder really options in trying out different components due to space issues. So if people want to learn PCB software and choose this design to due it with I do not see the issue. Hell I am learning KiCad with the Pass Pearl 2 which has been out forever.
And on a side note, if NOS tubes are cheap where you are please post where you are getting them from. I am about to get some Tun-Sol 6550 tubes and it is about 700 for a pair.
And on a side note, if NOS tubes are cheap where you are please post where you are getting them from. I am about to get some Tun-Sol 6550 tubes and it is about 700 for a pair.
No big deal! You could fix the “original wrong PSU board” easily. See how:
Oh no...not another Baby Huey EL84 build.
Or you could do this: Oh no...not another Baby Huey EL84 build.
Yep. I have all the notes and pictures saved for my version (MK2)
The hard part of this thread, or any long thread (e.g. MyRef Fremen) is that that go off on a side jaunt, then come back, then go off, and you really have to pay attention to follow what are the "better" configurations or any fixes to problems that come up. It really requires reading the whole thread. Then of course if you don't catch that a revision to the board was done you can get lost as well.Then never mind a BOM
I'm currently using Gbowling's from post #635 for the PS and the original amp one as a reference.a summary in a wiki as it exists for the EL84 version would be very desirable !
Baby Huey PP EL84 amplifier
Baby Huey PP EL84 amplifier
"Engineer's" Baby Huey - draft KiCad files
Hi all,
A while back I started working on an "Engineer's Baby Huey" - taking the BH design and trying my best to simplify the BoM and also adopting some of Pete Millett's techniques that he applied in his Engineer's Amplifier / DCPP.
Having built a DCPP (in daily use) I was keen to make something that used valves that would be available in 10/20 years' time - I've struggled to get the valves the DCPP uses here in the UK.
Seeing some of the recent discussion, I thought I'd share the below link:
amps/HiFi-BabyHuey at master * tristancollins/amps * GitHub
It's very much a WiP - still to do the layout properly and undecided on certain aspects of the circuit. It'll be my summer project. Schematic attached.
Features:
- a single PCB with all circuit elements needed for a stereo build, to the same dimensions as a DCPP board
- AC heaters
- Copying the DCPP HT circuit
Feel free to take these files as a starting point. I'll be updating the repo as I go and will make sure the KiCad source and gerbers are available (once built and tested) so people can order boards as and when they want. Happy to take suggestions / pull requests too. It'll take me a couple more months...
Tristan
Hi all,
A while back I started working on an "Engineer's Baby Huey" - taking the BH design and trying my best to simplify the BoM and also adopting some of Pete Millett's techniques that he applied in his Engineer's Amplifier / DCPP.
Having built a DCPP (in daily use) I was keen to make something that used valves that would be available in 10/20 years' time - I've struggled to get the valves the DCPP uses here in the UK.
Seeing some of the recent discussion, I thought I'd share the below link:
amps/HiFi-BabyHuey at master * tristancollins/amps * GitHub
It's very much a WiP - still to do the layout properly and undecided on certain aspects of the circuit. It'll be my summer project. Schematic attached.
Features:
- a single PCB with all circuit elements needed for a stereo build, to the same dimensions as a DCPP board
- AC heaters
- Copying the DCPP HT circuit
Feel free to take these files as a starting point. I'll be updating the repo as I go and will make sure the KiCad source and gerbers are available (once built and tested) so people can order boards as and when they want. Happy to take suggestions / pull requests too. It'll take me a couple more months...
Tristan
Thanks Tristan,
This will save me a lot of time and a separate effort.
Looking forward to this build.
Kind regards,
Earl Josh
This will save me a lot of time and a separate effort.
Looking forward to this build.
Kind regards,
Earl Josh
Tristan,
Did a quick once over. Looks good.
The shunt feedback set resistors R323, R423 are 18K in my amp (with KT77s). Fairly sure 39K is too big, as you increase that resistor the amp does clean up a bit but starts sounding "dry" and solid state'ish. It also throws extra demands on the diff amp front end and sound is likely to be more determined by the front end than by the output tubes.
In the EL84 version I ran 16K for these resistors and for the 6V6 version with 39K resistors from the output tube anodes (instead of 47K) I used 13K
Cheers,
Ian
Did a quick once over. Looks good.
The shunt feedback set resistors R323, R423 are 18K in my amp (with KT77s). Fairly sure 39K is too big, as you increase that resistor the amp does clean up a bit but starts sounding "dry" and solid state'ish. It also throws extra demands on the diff amp front end and sound is likely to be more determined by the front end than by the output tubes.
In the EL84 version I ran 16K for these resistors and for the 6V6 version with 39K resistors from the output tube anodes (instead of 47K) I used 13K
Cheers,
Ian
Last edited:
Hi Ian, what a pleasure to read your interventions once in a while.
EL34 standard feedback resistor as per BOM and PCB is 39k.
I've done some tests and 39k is very clean but I feel it's too much.
I like it around 22k, or 33k for some harder music genres. 39k gave me a strange harshness on top when pushed, that I supposed (not measured) it was due to the driver. For sure has a better Zout.
KT77 have better curves on UL than EL34, so a lower value is possible (and preferrable). I still prefer the tone of the EL84 in this BH configuration, with 8k load and 23% UL taps. I haven't tried them with KT77, but I will do it with russians 6V6 shortly.
EL34 standard feedback resistor as per BOM and PCB is 39k.
I've done some tests and 39k is very clean but I feel it's too much.
I like it around 22k, or 33k for some harder music genres. 39k gave me a strange harshness on top when pushed, that I supposed (not measured) it was due to the driver. For sure has a better Zout.
KT77 have better curves on UL than EL34, so a lower value is possible (and preferrable). I still prefer the tone of the EL84 in this BH configuration, with 8k load and 23% UL taps. I haven't tried them with KT77, but I will do it with russians 6V6 shortly.
Thanks Ian. Noted. I'm tempted to use (shock, horror) a couple of turrets as the footprint for this component to allow "select on test" without lifted pads / easier soldering etc. That or a bit of free-style point-to-point from resistor-lead-clippings-as-temporary-turrets.
My transformers have arrived from Primary Windings and Toroidy, so just layout and a PCBway order to go. Heater current requirements may require a 2oz copper order and wide traces for certain areas.
Tristan
tristanc: Heater current requirements may require a 2oz copper order and wide traces for certain areas.
Hello
70u instead of 35u makes the board significantly more expensive, at JLC e.g. 10 times the normal price. it is also not possible to implement only certain tracks in 70u. When laying out, I remove the solder mask where it is necessary so that you can apply additional tinning, if necessary, solder an additional wire. in places where it is possible, you can also arrange the tracks on both sides of the board.
Hello
70u instead of 35u makes the board significantly more expensive, at JLC e.g. 10 times the normal price. it is also not possible to implement only certain tracks in 70u. When laying out, I remove the solder mask where it is necessary so that you can apply additional tinning, if necessary, solder an additional wire. in places where it is possible, you can also arrange the tracks on both sides of the board.
