HI, first post from an electronics newby. Pardon my ignorance if this doesn't make any sense.
I've got a Award Session Bluesbaby 22 that I absolutely love, I'd love to try to build a less powerful version of it sometime. I've also got a Yamaha G50 112ii, G100-110ii and B100-115. I've got my share of solid state amps that all sound wonderful.
In an effort to compare a tube amp, I purchased a Nace M2-7R which is a 7 watt amp with a 12AX7 preamp tube and a 5881 power tube. It has a Accutronics Belton reverb module in it as well. The problem that I have with the Nace amp is that the reverb has a pronounced hiss that gets louder as you increase the reverb pot. It is the same regardless of the volume, treble or bass pot position. It's quite loud and can be easily heard over the amp at medium to low volume. Is this normal for a reverb module or is there something I should be looking for to correct it?
Thank you in advance.
Schematic?
The reverb module must feed into some sort of gain stage, and I'd wager that stage is the noisy part. I could be wrong.
Could you post a video or sound clip? The Belton "brick" reverb can be a noisy thing, but not normally to the point of being bothersome.
I don't have a schematic for the amp, but I can record a sound clip. I'll do that this evening.
Thank you for the help!
Think that I solved the problem. I took out the 6L6 tube and replaced with a NOS GE 6V6 and it really quieted down the reverb hiss. I'll have to check and see if the old tube is bad or not.
Thanks for the input again!
Keith
I like those Yamaha amps Keith.
Quote from: Keith7940236 on May 22, 2020, 03:38:55 PM
Think that I solved the problem. I took out the 6L6 tube and replaced with a NOS GE 6V6 and it really quieted down the reverb hiss. I'll have to check and see if the old tube is bad or not.
Thanks for the input again!
Keith
Ummh?? Generally 6L6 and 6V6 are not interchangeable. There is a good chance the 6V6 will burn out.
I'd be checking with the maker before you swap out power valves.
Phil.
This particular amp is able to run EL34, 6V6, or 6L6 as the power tube (plug & play).
Changing the power tube must affect the entire hiss level of the amp, not just the reverb. So if it was the power tube that made the difference, there must also have been more hiss in the dry signal previously. Maybe it wasn't as noticeable, but it will have changed as well.
Either that or something else cured it (board flex etc.) and it just happened at the same time as the tube swap by coincidence.
Easy to check by putting the old power tube back in and listening closely as to the hiss level in the dry signal with reverb turned off.