Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Josiah on January 04, 2017, 04:07:31 am
-
Hi, I'm new to the forum. I play Fender a 49 Tweed Pro and was wondering where to place a master volume in the circuit. I put a ppimv in my 50 watt Marshall and my Deluxe Reverb with good results. I've read that with the cathodine phase inverter I can go with a pre phase inverter master, but I am unsure of where to place it in the 5C5 circuit. Any help would be much appreciated. Thanks, Josiah
-
Welcome to the forum! Is this a clone and not an original? IF an original, please don't do mod it. IF an original you could lower the phase invertor tube to a 12AT7 and install JJ 6V6's to lower the volume. (presuming yours has the 12AX7 phase invertor instead of the 6Sc7). You could also use an attenuator.
Having said that, I am thinking you shouldn't have much volume with that amp with 12AY7 preamp into a phase invertor into the cathode biased 6L6's. I have two cathode biased 6L6 amps with are between 17 -23 watts and are great for playing at modest volumes.
With respect, Tubenit
-
And so if it is NOT an original, DaGeezer came up with a cathode biased attenuation switching idea yrs ago that works quite well and this might be a suitable option for your amp. I have used this in several amps and it does a decent job maintaining good tone.
http://el34world.com/Forum/index.php?topic=4437.0 (http://el34world.com/Forum/index.php?topic=4437.0)
And while I don't hear much change with pentode/triode switching on 6L6's, I do on 6V6's. So if you installed 6V6's in the amp and used triode, then that would lower the volume.
With respect, Tubenit
-
I have NO idea whether this idea would work or not for a 5C5 Tweed Pro clone ????
So, I thought I'd post it for discussion.
With respect, Tubenit
I've never heard of anyone asking for a master volume on a Tweed Pro before? :dontknow:
-
Here's a different idea, for the sake of discussion.
This would only reduce volume, and not give you an actual 'zero' volume setting....but it would also change the characteristic of the phase inverter, which you 'might' like :dontknow:
I have not tried this, but it is loosely based off of an idea presented in a recent thread.
This would be a simple idea to implement and try.
You should wire the pot in reverse of how we 'normally' would so that max resistance is achieved at the lowest counter-clockwise position of the pot rotation.
I am expecting someone to come along and tell me that it's not a great idea because ___________
-
I am expecting someone to come along and tell me that it's not a great idea because ___________
1) It puts DC across that pot, which we try to avoid because it makes for a scratchy volume control
As a different approach, you can tack a 10K resistor in there just to see if it's something worth your time.
That 'could' be put on a switch later as a switchable attenuator....not really a master, but a decent(?) way to get a set reduced volume
-
I've read that with the cathodine phase inverter I can go with a pre phase inverter master
But this is a paraphase inverter and you already have volume pots that feed directly into the phase inverter. It's such a simple amp. I don't see a need for a master volume. But if you just gotta, the crossline MV would be very easy to try. Connect one end of a 500K pot to one of the 6L6 grids. Connect the wiper of that pot to the other 6L6 grid. Done.
I don't really like this type of MV but some do. Maybe you will too. When set to zero, the crosslink mv acts just like the standby switch on the Silvertone 1484.
-
Thanks for all the input, this is really a great forum. It is an original 49 Pro that I redid myself, caps were leaking, output transformer was blown, speaker blown, cabinet busted up, etc. So its had some work done already. I tried the cross line MV with 500k and then 250k. It works pretty well but really seams to make the highs harsh. I may try the attenuation switching next or a better attenuator. I wired up an L-pad style attenuator with a bright cap but it just doesn't sound that great on this amp. It is my main amp and I love the tone, I just need to knock the volume down at certain gigs, still get the growl and I'm not a big fan of overdrive pedals. I may just start bringing a Tweed Deluxe to those smaller rooms...