Blueman2

Tube boards are best to be 2mm.

BTW, are those EL34s Tung Sols? Edit: I see in the reflection they are Svetlana's. Great picture!

That is a work of art. Congratulations!!!! So many great ideas and touches, I want to steal them all!

I know JimL designed and built a shunt PSU for the SRX-Plus. Great article on it in AudioXpress I can send you if you want.

Given the fixed setup cost, you might want to ask @sbelyo to get a quote for 2 or 3 sets rather than just 1 set. Price will only go up marginally, and you could probably sell the others later. Or keep them in case one or two boards blow up and need to be rebuilt!

@sbelyo, Can you put me down for 1 additional pair of GRHV boards (so 3 pairs total)? And 1 additional GRLV board (3 total)? Will you be PMing everyone your paypal address for payment?

And for Grounded Grid: Basically a Carbon with Tubes. Or others might call it a Blue Hawaii with updated design. I prefer the former description.

Here is the Carbon v.6 Grounded. Latest version that I know of. kgsshvcarbonv6ground2.zip

Adjusting up is usually not an issue. Adjusting down is more frowned upon since it can increase the cost to others.

Did not see the Grounded Grid file on first page, but I think this is the latest version. gg.zip

The STN9260 is the closest I see at Mouser. Collector/Base gain is the only thing that is off a bit.

Ah!!! Direct heated triodes! That is what dht meant. Thanks for the clarification. Removed the DHT files and left only the regular one.

I think these are the latest gg Gerbers. I will add to the spreadsheet. Since tubed, I will spec 2mm board thickness. gg.zip Yes, these work well with the BH. Good clean power with the ability to add timer function for the HV section. This allows the tubes to warm up for about a minute before the HV kicks in. The only real question is whether to use the on board Low Voltage which the GRHV provides, or whether you want to go with separate GRLV board(s). I used the GRHV on board LV supply and it works fine on my BH-BJT.

I would be in for another set of these boards. The BH-BJT has become my favorite amp these days. Just love it. I would like to have another set of boards in case my son or brother decide they cannot live without one. Here are the gerbers. kgbhver6sbipolar.zip

Note to people signing up for the GRHV boards, this is the pair of boards (Left/Right or -/+). The pair are what you typically need for one high voltage amp. DronEvil, samsie and bluebyte60, you signed up for 4, which means enough for 4 HV power supplies. Just wanted to make sure you wanted that many.

Yeah!!!! Congratulations! Great news. Yes, buying parts from a reputable source (Mouser or Digikey here in the US) is a hard learned lesson for many of us. The other lesson I have learned is minimalism in amount of solder. My Carbon went south about a month after build, but with sorenb's help I found I needed to remove excess solder and recheck all the joints. No issues since. But I am really happy you got your baby up and running. For case, I recommend one with big external heat sinks. The carbon really puts out the heat. Well done, bui501!

Bui501, I did the exact same as you 2+ years ago. I bought my 10M90S from eBay, China source I think. Look at my thread "Exploding Zeners" below. I am still not sure what exactly was going on with my 10M90s 'popping' but once I went with all Mouser, no more problems.

bui501, are you able to take a clear high resolution picture of the front and back of your board? That would help us see potential issues. The good news is that I too have had numerous similar issues during my 4 amplifier builds, but when I diligently listened to what sorenb and other said, I was able to solve the problem so you will too! My encouragement is to do exactly what sorenb advises, step by step, and you will find the issue. My issues came when I assumed I had done a step sorenb (and others) advised, but really had not done it correctly. Particularly in terms of amount of solder and good solder joints.

Yeah, my post is actually somewhat in jest. I strongly recommend the Cree since it has more proving time behind it. But if someone is impatient and does not mind risking burning down their house when something goes horribly wrong, then the ROHM is always there!

Or you can use the ROHM device as a backup, as it appears to have worked great in my build!

I have been hearing nothing but good things about true (beam tetrode) 6CA7s. Might have to give them a try sometime. I like the Tung Sol EL34Bs (pentode I think) I am using, however.

I agree that the servo on the BH is probably not necessary. It is fine after about 10-15 minutes warm up. But I love a challenge, and getting a servo installed on my BH sounds like as good a challenge as any. JoaMat is kindly giving me some advice and direction, and I will report back when I have a pair of servo daughter boards created and working for the BH (fingers crossed). Back on the topic of the BH BJT itself, it really is an amazingly pleasant amplifier. Yet I can't say what it is about the amp that is so good. A/B testing with my Carbon and SRX don't really tell me anything. I honestly cannot tell a big difference. Yet listening to the BH for an hour or two leaves me feeling so good, whereas the Carbon is a bit more fatiguing. Not saying the Carbon is not great, I just find it less suitable for listening to for a couple hours while doing other work. I find I am using the BH for my 'ambient' amp, where I want to listen to music for hours at a time while doing other tasks. I tend to use the Carbon for my 'critical listening' amp where I want to really focus on the music without other distractions, at perhaps a bit higher volume level. My SRX is a great amp for both use cases.

Correct. Right is Positive with Bias voltage supply, Left is Negative with low voltage supply.

You are correct! The sws adds an extra position for the SiC chip mounting hole which helps. So the sws version is the one to use. Files attached below... kgsshvpssicfetsinglenewleftfatsws.zip kgsshvpssicfetsinglenewrightfatsws.zip

I am getting quite a drift in offset for my BH BJT. To get it to zero out at full warm up (about 50 minutes), I have to start it at -45V on one side and -35 on the other. Balance stays good on both sides, starting around 3-4V but always getting to less than 0.5V at full warm up. In a discussion with JoaMat regarding Servo1 vs. Servo2 for Carbon, he mentioned it would be possible to do a daughterboard for the BH and tie it in to tame the offset drift. Looking at the schematics, the BH BJT and the Carbon (and for that matter all of the KG designed ES amps I have seen) share a very similar architecture, so transferring the Servo design should be doable. I think JoaMat did this successfully. Has anyone else done this? I was going to try to come up with a schematic for the daughterboard and how to tie it in to an existing BH, but wanted to see if I could leverage off the work of others first. BTW, if I am wasting my time worrying about the offset on the BH, please tell me. Or if there is another way to attack offset, I would be curious. I moved tubes around and that did not seem to make much difference. Big thanks to JoaMat who gave me nice background and tutorial on the Servos.