Blackheart BH1 SCHEMATIC.

[Cassiel]

It claims 1W but they probably missed a decimal. I'm posting this because you don't see this everyday. I wonder about the OT they used, I also wonder about the fixed tone stack and, lastly, I wonder what these guys are smoking because I don't get the output stage. Why didn't they choose the 12AU7 or ECC99 as the output tube? Maybe too much power? I'm really curious about the sound of this, was going to prototype it but where do I get an OT with this sort of impedance?


EDIT. Sorry about the pic, you'll have to download it and open it with an image viewer. Originally PDF file and the size was too big to post it as it was.

[Cassiel]

Power stage resized.

[tinitus]

Originally Posted by Cassiel

I wonder what these guys are smoking because I don't get the output stage.

I'm really curious about the sound of this.

its a distortion machine

the video clips I have seen/heard was 'promising'

I expected there would some kind of solid state curcuit involved in the output stage
But obviously not

I dont know, but could the output trafo be some form of interstage thing, with gain

[Trout]

I figure the fixed tone stack is a result of achieving the low cost point.
Likely the values are also set to keep things at least close to what the cheapie OT can handle as well.
You could easily mock that circuit up with a typical tone stack. Most certainly You could also upgrade the OT without breaking the bank.

Lots of mod kits for those around.

[Cassiel]

Lots of mod kits for those around.

I didn't know this was a 'famous' amp. Yes, you can find mods some of them don't make sense either... like power scaling. An amp with an 12AX7 output tube needs power scaling? Am I going mad? Anyway after reading the manual I gather the output triode won't live long (no wonder) so this it's just a wrong design and my curiosity is over. It's just plainly wrong and stupid.


BTW there was a thread not long ago, in the tubes forum....somebody was asking how much grid current could take the 12AX7 without going bad. Well, buy this amp and find out for yourself.

[Trout]

Originally Posted by Cassiel

I didn't know this was a 'famous' amp. Yes, you can find mods some of them don't make sense either... like power scaling. An amp with an 12AX7 output tube needs power scaling? Am I going mad? Anyway after reading the manual I gather the output triode won't live long (no wonder) so this it's just a wrong design and my curiosity is over. It's just plainly wrong and stupid.


BTW there was a thread not long ago, in the tubes forum....somebody was asking how much grid current could take the 12AX7 without going bad. Well, buy this amp and find out for yourself.

That amp could actually benefit using a 12AU7 or even a 12AT7 in place of the AX7.
There are actually a pretty good number of fly size DIY amps around like that. Some actually sound pretty darn good with the right cab.

As far as VVR goes I totally agree, its only marginally a 1W amp.
There still seems to be a lot of bedroom guys that can not run even a 1watt cranked.
I remember years ago when I lived in an apartment I could only find practice time around 2am, I was limited to my old Scholz Rockman

[shanx]

An amp with an 12AX7 output tube needs power scaling? Am I going mad?

No you are not going mad..it is people marketing silly things on the internet. But for people who want to have a more ''reasonable'' lunchbox amp that is 4W but switchable to 0.4 W check the specs on the Gem 2G by Mack amps. I have one and it kicks out pretty decent at 4W and still get same tone when switching down to 0.4 W. I am not trying to plug the company but IMO they are doing a very good job. Could be cool to review on DIY a bunch of micro tube amps and see which ones stand out quality wise, based on FB from members.

[tinitus]

seems I mistakenly thought this was about the small Blackstar HT-1R

ouch
sorry about that