OD volume

[phillyhudson]

hi
just built HRM type amp that sounds great but at the last couple of gigs I,ve used it at - I have the OD volume flat out and its still not as loud as the clean sound which means I have to turn up the master volume to compensate which means the clean channel becomes too loud.Amp voltages all check out ok and I,m really pleased with the sound , I,d just like the lead volume to be up a bit - any suggestions please ?
ta
phil

[benoit]

hi
just built HRM type amp that sounds great but at the last couple of gigs I,ve used it at - I have the OD volume flat out and its still not as loud as the clean sound which means I have to turn up the master volume to compensate which means the clean channel becomes too loud.Amp voltages all check out ok and I,m really pleased with the sound , I,d just like the lead volume to be up a bit - any suggestions please ?
ta
phil

What schematic did you use? An HRM has separate masters for clean and OD if you built it like HAD, so you should be able to set each one totally independently.

So turning up the "master volume" is only turning up the cleans, unless something is wired wierd.

Another thing is the OD trimmer might need tweaking.[/b]

[phillyhudson]

following 101 schematic and youre right - they should be independant and theyre not so I,ve wired switch up wrong - thanks for help !

[phillyhudson]

sorry-just checked - the od does go via the master vol so when I,ve got the lead vol flat out and its stil not as loud as the clean channel - I have to turn up the master and thats where my problem is !
any suggestions please ?
ta
phil

[Structo]

Not sure I understand your amp but in mine which is a non HRM amp, there is a Preamp volume and a Master volume.
They work together.
If the preamp volume is turned way up and the master is not turned up it induces preamp distortion on the clean channel.

So I find a happy medium between the two to get a nice clean tone or as dirty as I like.
Then I adjust the level control for the OD channel to adjust the balance between clean and OD.
I generally have the clean channel a little bit louder than the OD channel because the OD channel sound louder due to the distortion.
When I need a boost for solo or chorus work, I step on the PAB footpedal.

[phillyhudson]

thats what I want from my amp aswell ! but because the lead master is flat out and still not as loud as the clean then I have to resort to turning up the master volume to try and get more out of the lead channel which in turn puts the clean channel up.A simpler way of putting it would be - how do I get more volume out of the lead channel on an HRM amp ?

[Structo]

Well then something isn't wired right obviously.
I know that isn't any help.

So did this amp ever work right?
You said after a couple of gigs the OD volume went away.

So this is something that has happened gradually or all of a sudden?

Where do you have your HRM trimmers set at?
Where is the OD trimmer set at?

Somebody here had a HRM that didn't sound right and he found he had a defective trimmer on the HRM board.

I'm sure you have tried other tubes in it right? to rule them out?

[phillyhudson]

sorry-havnt explained it very well - the amp works and sounds great,the only thing I have a problem with is that when you do a gig [as you explained in previous post] you set up the master volume relative to the gain you want from the pre amp and the OD master [or ratio] vol,but when things get a bit a loud , you usually want the OD sound to be louder than the clean and what is happening with my amp is I have the OD volume flat out but its still not quite loud enough relative to the clean master.I,m only talking at quite loud [un-miced] volumes here because its not a problem when you can set it up at lower volumes , then you have enough "to spare" in OD vol.I just wondered if there was any way of getting more level [not gain] out of the lead channel ?

[Normster]

It's been a while since I've played an HRM amp, but I don't recall ever having lower OD channel volume. If you've followed the HRM schematic, I assume you have a 250kA OD gain pot and 1MA for both the clean and OD masters? Trimmer set at about 24k to ground? Gain set at about 11:00 o'clock? At those settings, your OD and Clean masters should be pretty close to equal, at least up to about 12:00 o'clock.

[Structo]

Yes, sounds like the OD trimmer is set too low since that controls the gain of the OD.

[phillyhudson]

thanks for replys lads - yes I have the usual 250kA OD gain pot and 1MA for both the clean and OD masters and I didnt want to fiddle with the trimmer anymore coz I really like the gain set up as it is - but your'e right it is set very low - I,ll just have to put it up then sort out the gain on the front of the amp.Thanks again - I owe this website and the kind people involved an enourmous amount - you,ve allowed me to build amps that sound twice as good as the stuff I,ve wasted loads of money on previously.

[phillyhudson]

just to let anybody know who might have had the same problem - it WAS the wiring on the relay ! I wasnt aware but the HRM is slightly differently wired than the non-HRM - the former has completely seperate clean/od master vols and the latter has the master vol as a master volume for BOTH channels.
Thanks again for a fantatsic forum !
phil

[Structo]

That's great you figured it out.

I messed with my amp the other day and following some advice I adjusted the OD trimmer to 26K wiper to ground.
It really smoothed it out, I had it set lower before.