Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Toxophilite on April 03, 2015, 04:24:48 pm
-
So in rehearsal the other day , with my newly finished amps i was noticing a significant lack of high end!!
I unplugged this and I unplugged that but I neglected to take the standalone reverb out of the circuit
I figured it was a pedal board problem.
So I was messing around when I got home and discovered it was the reverb unit
Some searching showed this was how the mixing pot worked (rolling off the dry signal top end as it gets turned up)
I really don't like this as I generally use reverb(when i use it) in a big way , as an effect or in a full on surf capacity, turning it on and off with a footswitch. I also like a crisp tone for a lot of things
is there a simple mod for this? ( I tried shorter cables and it still does it) other than the add a tube buffer thing they did in the 70s?
-
Is there no easy way to rectify this high end loss ?? a cap across the mix pot?
-
I have not experiences a high end loss with my revibe. But my ears are not good enough to say I don't have a high end loss.
The tone control is a simple tone suck variety. Temporarily disable it to see if that makes a difference. Just unsolder the 250pF from the mix pot. Then move the wire from the tone pot to the mix pot. Does that help?
-
I built this true bypass switch to go with my Son's 6G15. (He has not had to use it). If all else fails give this a try. Simple build.
http://www.stewmac.com/How-To/Online_Resources/Pickups_and_Electronics/Build_this_bypass_pedal_to_turn_your_stompboxes_OFF.html (http://www.stewmac.com/How-To/Online_Resources/Pickups_and_Electronics/Build_this_bypass_pedal_to_turn_your_stompboxes_OFF.html)
-
The high end loss occurs in the dry signal as the mix control is turned up
The other controls seem to have no impact on the dry tone( the tone control works really well with the reverb sound as I believe it should)
I like to turn reverb on and off as an effect, In some songs I use it all the time
But mostly I'm using a dry sound with echo and turning the reverb on and off
So if I have the control halfway up and I turn it off I have a pretty dead sounding dry signal
I have read this is common to this design, having to do with the capacitance of the cable to the amplifier from the unit
If you scroll down to mixer control on this link it describes why
http://wiki.surfguitar101.com/ReverbFaq (http://wiki.surfguitar101.com/ReverbFaq)
Just curious if anyone had discovered an easy fix to this other than a really short cable
(I'm using a 6 ft one as the unit is not sitting on my amps which are leaning back)
-
That tone control is meant for the wet signal but it is always in the circuit so it will affect the dry signal too. Humor me. At least disconnect the 250pF from the mix control. This will totally disconnect the reverb circuit. You will have dry signal only, but you will positively know if that is responsible for your tone suck.
-
Sure I'll open up the unit and try it
I wasn't resisting the idea
I was just experimenting with the controls and the reverb off prior to pulling it apart to make sure what I was relating was accurate
At that point the mixer control made a big difference(turn it up , high end goes down)
The tone and duration didn't seem to make a difference, however I will try that and let you know. likely this eve. off to go hiking now
Edit; shortened dead page space.