I have a Fender HRD that I'm struggling to get sounds I'm happy with anymore. I almost thought about flipping it for something else thinking it just wasn't for me but I'm sure I remember it sounding better than it currently does. Its an older Tweed covered one and has a cream back 65w in it.
EQ changes don't seem to affect the sound much. Bass and mid on 0 and it's still boomy and woofy. If I crank the treble and presence it goes from dull to brittle without anything in between. It just doesn't sound very even at any settings I try.
So far I've tried swapping v3 for v1 which did add some top end back. So I swapped the duller one into v2 because I don't use the second channel.
I also tried swapping power valves but the spares I know are worn and it didn't affect the sound.
Maybe I just need to revalve it? Or possibly something else that a tech needs to look at? Anyone had a similar experience?
Comments
Have you always had that speaker in there?
contactemea@fender.com
contactemea@fender.com
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Not really, unless you want to use either an external bias adaptor - which will do the same thing, but one valve at a time - or to meter the voltage drop across the OT, which is the most accurate but dangerous if you don't know what you're doing.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
You are probably safe up to 70mV at the test point with any of the regular types unless you are seeing a really high wall voltage. My old flat used to be about 246V the amp is specced for 230V so the plate voltage was about 456V rather than the 430V on the schematic. I used to bias it so that it was slightly on the hot side at home. When I was playing out it was probably running slightly cooler.
You don't have to go that high though. The 70% of the max plate dissipation guideline is generally regarded as a maximum value. If you like the sound at 60mV then leave it there as the valves will last longer.
Having said that I don't think it sounds like the power valves are the most likely problem. I would agree with what's been said above that it's more likely to be the preamp valves if it's valve related.
I swapped in the Tungsols and it made no difference to sound or the noise floor.
I swapped in the JJs and the amp came back to life! I still need to re bias it but it was definitely the power valves!
Can't wait to get it sorted and crank it up to see how it sounds now