A few years ago I messed around trying to build inexpensive guitar amps using old tube combos that would run on series AC heaters. The big cost saving being NOS high build quality tubes costing single digit dollars (e.g. 50L6 GTs) and no need for a specialized power transformer with a high current heater circuit. The downside being pre-amp noise and the surprising variability of wall voltage. Of the two the noise was easier to deal with. Tubes can tolerate a fair amount of operating voltage variability, but heater voltage variability really kills their performance. Ended up having to employ a rather uncommon TI voltage regulator and heat sink, which was adding about $10 to the cost of each build. Topology was a little unique, based (IIRC) on a Mojave amp that had a pre-amp consisting of a high pass (treble) circuit and a low pass (bass) circuit that were then blended using a stacked linear pot before the final gain stage. Gave a surprising range of tones, but ultimately proved too damned finicky to be considered anything gig worthy. Still have a couple prototypes sitting on a shelf in the garage.
I bought a cheap 6J1 preamp from China. Really sounds better in my otherwise solid state system! It was beautifully and exoertly designed and built. Works great! No added noise.
The only problem I found with the preamp board is they use a 12VAC supply that runs into a voltage multiplier to run the plate voltage. The problem is the caps are rated at the same voltage they run at in circuit. I already had a cap blow up because of it. I had to buy new caps rated 100V and replace them. It works great now but not cool having caps blow up in your face.
I had the same problem, only mine was self caused. My first kit came missing a bunch of caps, so I just used some 16v instead..... maybe not the smartest idea because eventually two of them puffed up and fizzled out some juice before I noticed it and shut it down.
Really interesting. Links to the three main components would help but I found two out of three anyway. That just leaves the mystery power amp. Cool idea though. I'm not an electronic genius but I think I could do this, very inspiring....now how 'bout that amp? Many thanks for this.
Cool~ Very interesting build! Greetings from HK.
I just watched all your videos. #45!
You can have top spot in my army of domination. Just gotta figure out how to order an army of domination on amazon.
A few years ago I messed around trying to build inexpensive guitar amps using old tube combos that would run on series AC heaters. The big cost saving being NOS high build quality tubes costing single digit dollars (e.g. 50L6 GTs) and no need for a specialized power transformer with a high current heater circuit. The downside being pre-amp noise and the surprising variability of wall voltage. Of the two the noise was easier to deal with. Tubes can tolerate a fair amount of operating voltage variability, but heater voltage variability really kills their performance. Ended up having to employ a rather uncommon TI voltage regulator and heat sink, which was adding about $10 to the cost of each build. Topology was a little unique, based (IIRC) on a Mojave amp that had a pre-amp consisting of a high pass (treble) circuit and a low pass (bass) circuit that were then blended using a stacked linear pot before the final gain stage. Gave a surprising range of tones, but ultimately proved too damned finicky to be considered anything gig worthy. Still have a couple prototypes sitting on a shelf in the garage.
I bought a cheap 6J1 preamp from China. Really sounds better in my otherwise solid state system! It was beautifully and exoertly designed and built. Works great! No added noise.
Can you do a step by step build
The only problem I found with the preamp board is they use a 12VAC supply that runs into a voltage multiplier to run the plate voltage. The problem is the caps are rated at the same voltage they run at in circuit. I already had a cap blow up because of it. I had to buy new caps rated 100V and replace them. It works great now but not cool having caps blow up in your face.
I had the same problem, only mine was self caused. My first kit came missing a bunch of caps, so I just used some 16v instead..... maybe not the smartest idea because eventually two of them puffed up and fizzled out some juice before I noticed it and shut it down.
That's a cool little project
Really interesting. Links to the three main components would help but I found two out of three anyway. That just leaves the mystery power amp. Cool idea though. I'm not an electronic genius but I think I could do this, very inspiring....now how 'bout that amp? Many thanks for this.
Is it fused?