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This is a trace I did from the Nobelium PCB when I got my PCB, I think it is correct but I will not guarantee it. I always trace any PCB I get to better understand the circuit before I build them. Cheers Mick

It sound just perfect for what I want, my Ashdown ABM500 is the only bass amp I have at home at the moment and it is just a little bit to big for indoors (so I have been told). I think a small versatile amp I can use with pedal preamps will suit me just perfect for guitar and bass at home, I...

The 12AT7 can go up to 15mA in JJ's datasheet, but then we are talking about the limiting current. I would think that an amp that is warming up and no signal it should not pull much at all on the HV, when max signal is applied it would increase the mA but not all the way to the max mA the tube...

The mounting pin of the potentiometer connects to ground and so too does one leg of R19. It looks correct to me, they should both be connected to ground.

I would increase the resistance of the 470k resistor (R21) that is on the left side of the 100uF capacitor. I thought that the bright cap (C13 180pF just above R21) would cause the highs to bypass the volume pot, especially at low volumes. The Bright cap would also bypass the added resistor on...

A rough guide to the gain of the valves

I really want to order some boxes with the slots milled out from Tayda but I keep hesitating. How exactly do you order them and how do they know which box is for which drill template? I want to order an Ambassador, Bassdude, Black Eye, Mirrage Tremolo, All 1590BB size. I also would like to order...

Would it be possible to see the schematic for the power amp you are running on the HV PCB ??? Since a few of us would like to try making a pedal power amp it would be great if you shared it, even greater if you had a PCB we could buy. I can easily make up a PCB if I have the schematic but if you...

I have seen some fairly basic tube compressor circuits, but there would be no point in making one if a basic $50 cheapie China pedal would sound better. To make a great tube compressor could be a bit hard for some people, I am not a big fan of surface mount (yet). It can be hard to not fall into...

Here is a Bass mod I am thinking of doing to one of the Ambassador PCB's I have ordered, it also shows how I would change the separate channel switch to Clean/Both/Gain with a DPDT on-on-on switch when I make it fully bypassed like above.

Here is more info on the HTM1 build that Creach showed above.

Another option would be to run the power amp at less voltage, but I am pretty sure you would have to run a different impedance tap on the transformer. I haven't read up on how to calculate that yet myself, maybe someone else can help you out there.

Mike, are you using 9V or 12V into the HV smps and can your supply provide enough amps ? I was thinking of doing a Rob amp myself with the power amp in it's own separate box. I was going to try a single ended amp with one 12AT7 tube running it, not much output but if it works I will be happy. I...

I drew the Ambassador up in KiCad and made some pics of how I would wire it for a separate channel switch and use the foot switch for effect on / bypass. (True Bypass) Last 2 pics is where I would place the channel switch, I would use a 2M switch as they take up less room...

I think you can get away with just altering the pins going to the switch, or actually removing the links from the PCB to the switch PCB in the right places. Start with removing the links on 1, 2, 3, 4 from the PCB to the switch PCB. (Component side I call the left side 1 and right side 9) Jumper...

I just ordered some Ambassador PCB's even though they are not in stock. Vigilante has some with blemishes that he can sell cheaper until they run out, you can't read all the components because of a printing error but you can look at the build doc and clearly work it out. Check out post 167 to...

I am thinking about using a power supply out of an old HP rack server I bought a long time ago because I wanted the RAM from it. I think it is 12v at 800 watts so I would never have a problem again. I think the power supplies from computers can be very useful when converted, most laptops have...

The second link is a good well known seller, I have used their Australian store (Element14) many times in the past. Newark is known by different names in different countries, they used to be called Farnell in Au many years ago, the company I used to work for then (Pirelli) used them for quality...

I would be happy with a blemished PCB since the build doc shows where the components go.