allan_steen_iversson's Reviews
Thank you for your hellpful indsight, regarding my good old eighties V 15`teens. I did not entirely cut the brown lead. Instead i drilled a switch into the alu chassis, so I could turn the negative feedback on again if needed. An so I have with the one of
Thank you for your hellpful indsight, regarding my good old eighties V 15`teens. I did not entirely cut the brown lead. Instead i drilled a switch into the alu chassis, so I could turn the negative feedback on again if needed. An so I have with the one of them, that suffered from microfony. Regarding my Vox ccx1....I found it too harsh and sharp in treble to my ears, and have done a modification on it. These new amps all have a bright capacitor sitting in parallel....mine at position C26 on the Pcb board. By cutting the one leg, pushing the cap back a little, I have got quite a different beast now. Much more creamy and warm, and still with all the chime and power when needed. The old AC fifteens did not have this capacitor. This is a newer invention in order to add treble at lower volume, But actually the treble follows up to a degree of volume, that makes it a bit annoying when playing minor venues. So I do consider this rather mod for being very successful, and I am very pleased with the result
41013
actually the old amps have the bright cap, tis actually the coupling caps that are lower values making the rest of the am brighter, but the bright cap mod is popular. You could also check the cathode resistors on the power tubes against vintage, I bet they are a non-vintage value making the amp colder and more brittle in the treble frequencies. Vox has actually been running the cathode bias cooler and cooler since always. My 62? you can fry an egg on it. It once caught fire and needed extensive restoration.
There is extensive info online about measuring the voltage drop off the cathode resistor and finding a safe but musical value for an ac30. Or if you wanna play it real safe and still sound killer look at the matchless schematic or the schematic for the fawn handwired AC30HW2, both have a sweet balance of reliability versus unfatiguing treble and I think are both rpetty close to a alte 60s ac30. I would tell you to look a old schematics but they often don't match what's in the amps. Vox was tweaking the bias all the time.
41013
instead of a switch for the V15 why not install a pot to vary the amount of feedback, I am not sure how to implement this but I know I've seen it done on 6V6 fenders with NFB like the tweed tremolux and the non-tweed princetons... I think its called the "soul knob' mod.
41013
the soul knob is kinda like a full bandwidth presence control in practice, where a presence takes NFB off the high frequencies only
Hello Jimmarchi1 Good news according to the bad microphonic auxillary valve noise I was having in one of my V15`eens. In the V1 position, i exchanged the sitting ECC81 with a ECC82, which has a much lower gain factor, and puff - away is the noise...completely ! I am very happy with the result, and it even sounds a little more creamy when turning up the power, So I am a very happy Dane these days :O)