Not been here in a while....

Go on...

Building a little 2.5 ch preamp. Dont have an up to date schematic to hand although most stuff is documented over at HDIY.
Clean channel is VH100R ish (2 stage) with bright switch
Lead is 3 stage with cold clipping and plate driven TS.

An extra stage can be added after either channel with either a full range or mids boost by means of selecting the bypass capacitance. I know adding it to the clean works as its not far off what laney do in the VH100R, not too sure about the lead as it's adding gain after the TS which might be a bit odd. If it doesnt work then I'll invent some horrifying insert switching to move the boost before the leas TS.

When I've got it working I'm going to piss about with LED biasing for the input and lead stage 2 to see how it sounds. No need for a bypass cap then which should tighten the amp up.

Sounds gnerly.

Being currently too broke to build them, i haven't been reading up much on amps lately. Enlighten me about the LED biasing? Or post a schematic or link, whatever.

Its popular with hi-fi guys as you dont have the sluggishness of an electro for full range boost.

http://www.freewebs.com/valvewizard1/Co ... _Stage.pdf
page 34 onwards has some details on diode biasing. looks pretty cool. Theres a bit of compromise with what you can achieve but I'm going to have a tinker anyway. Looks a fairly elegant solution to fully bypassing the input stage at least.

AH! That is pretty fucking neat. I hadn't heard of that before. I will have to look into it further!

Its pretty cool. May try signal diodes too although LEDs will look better haha, especially since my board is translucent.

Board half(ish) populated. Got up to a 47K that was missing from the order so I'm calling it a night. I have some CR50s with the rigth value in but I havent sorted them yet.

Translucent board? That's fucking pimp.

Its pretty fucking swish . You can see all the under board wiring (yeah yeah) if you hold it to light.

Pretty much the board done except for a few minor parts that can go on when its ready to be put together

Very nice. I really like how much more compact the layout can be with radial electrolytics. I keep on meaning to buy a whole stack of them, but the last couple of builds, i have done with axial ones that i got dirt cheap, instead.

Thanks. I spent quite some time on that layout. Radials make good sense for the pre as it saves a hell of a lot of space and you don't need to fuck about with the grounding scheme so much. Id prefer axials for the reservoir but they're a bitch to find cheap. I'm looking at snap in caps if i want 220u 450v caps without getting my ass well and truely fucked.

Drilling big holes is a pain in the ass. Bought some punches. Dont think I'll get through 3mm with the 22.5 mm bits I have.

Oh yeah. Especially if the chassis is steel. Octal socket holes suuuuuckk. You can put a few 1" holes in an aluminum chassis with a new/sharp hole saw bit, but it will pretty much kill it.

I wish that proper punches were less pricy, but they are definitely the way to go.

It worker out cheaper than getting decent drill bits or a stepped bit. Got a 22.5 mm and a 27.5 mm punch for £17 shipped which is pretty much the price of one decent drill bit and punches are far cleaner.

Drilling the chassis was a pain in the ass anyway. It didnt quite fit under the drill press so we had to work around it and drill at an angle which is a little naughty. Ah well this is my prototype box and its a shitty grey colour. I'll do my nice zinc plated alu chassis with a bit more care

That is hot. Is it working, or are you still building?

'Cause if it is done, i want clips.

Still building that sumnabitch.

Got a whole bunch of soldering to do yet and I have to redraw some of the layout to work from as I need to mount my pots in the opposite orientation to how I've drawn the wiring I drew it with the lugs facing inwards rather that outwards which is much easier to solder to the board in this case.

Also I'm still waiting for the hole punch to arrive so I can err.. punch the hole for the valve sockets. I have some T50 fuses in the post too.
I hope to be up and running, or at least debugging, by the end of the week.

As for clips. I'll see what I can do but there will be something for people to listen to. The room with my gear is sounds shitty for the most part - Too harsh and the comb filtering sucks. I'll try and make a little fort made of cushions or some shit around the cab to deaden the room a bit. I can try running it straight into my interface and then tinker with impulses but I'm a stone cold noob with that.

Ha! I don't know how or why i didn't notice that the er... tubes, were missing!



Maybe i have been looking at too much solid state shit lately.