I'm new here, and I've been searching the internet for reducing volume on my Matchless DC30. Since I got my Badger 30 in November I've been interested in scaling my DC30 as well as I'm very impressed with the PS on the Badger. As you probably know, the master volume on the DC30 is not a good sounding solution unless it's bypassed
So a modification that bypasses the master volume on the DC30 and uses the place for the original master volume knob for another design would problably not be too hard to implement? A solution that sounds just as good as the power scaling on the Badger and with no modifications to the front panel (using the place for master volume knob for controlling the new circuit) would be highly desirable for this amp as it can get very loud.
I've got little but some experiece with the insides of tube amplifiers. So which method would you recommend? PS? VVR? Perhaps something else?
I've been doing some reading now and it seems VVR would be the solution with the least hazzle, so VVR it is! Have anyone here replaced the master volume on a DC30 with a VVR and can share some thoughts about the results? Can the VVR be bypassed by using a push-pull potmeter?
Yngve wrote:I've been doing some reading now and it seems VVR would be the solution with the least hazzle, so VVR it is! Have anyone here replaced the master volume on a DC30 with a VVR and can share some thoughts about the results? Can the VVR be bypassed by using a push-pull potmeter?
Hi Yngve
Welcome to the forum!!
Basically when the VVR is turned up to full power it is out of the circuit. You might lose a couple of volts B+ but that is about it. You could bypass it easily with a switch but I don't think it is really necessary. By the same token when you turn it all the way down it is like flipping the standby switch
Yngve wrote:I've been doing some reading now and it seems VVR would be the solution with the least hazzle, so VVR it is! Have anyone here replaced the master volume on a DC30 with a VVR and can share some thoughts about the results? Can the VVR be bypassed by using a push-pull potmeter?
Hi Yngve
Welcome to the forum!!
Basically when the VVR is turned up to full power it is out of the circuit. You might lose a couple of volts B+ but that is about it. You could bypass it easily with a switch but I don't think it is really necessary. By the same token when you turn it all the way down it is like flipping the standby switch
Thank you for your reply.
Yes I see that now, and maybe a push-pull potmeter can cause some serious spikes?
I've just sent you an email from the adress at the Hall Amplification homepage asking if you could send me the instruction manual so I can do some research before ordering in case I need to order something extra..? Probably a lot to ask prior to an order, but asking won't hurt I guess...
I've got to run out for a couple of hours. I will answer your email as soon as I get back. Here is a couple of links to a DC30 with VVR installed and also a Voxer with VVR
I received the VVR3 and installed it in my brothers Voxer 18 today. We think it's best to try it first on this amp as the Matchless is a lot more complicated inside.
The VVR seems to work as it does reduce the volume to speaking levels when the VVR pot is at minimum, and the amp is apparently at full power when the pot is maxed. At the min and max settings, the amp doesn't hum, but any settings in between (approx. 10 - 90 %) generates alot of hum. The volume is variable as expected, but we can't seem to figure out where the noise comes from.
We took the lead out from the standby switch and wired it to B+(in) on the VVR, and the B+(out) on the VVR goes to the choke. In short: Inserted the VVR between the standby switch and choke. The ground on the VVR goes to star ground (next to the power trafo), and the mosfet is mounted to the chassis with the insulator.
We think the mosfet is working fine as the VVR does reduce volume as expected, but we can't figure out the loud hum at in-between settings. When moving around the B+(out) wire when the amp is connected and powered, the amount of hum varies. Maybe electrical fields is resposible for the hum, interfering with the B+ leads?
I do know I had problems with hum in an amp when I had the B+ wire that went to the standby switch anywhere near other AC power wires.
Once I routed it away from those wires it became quiet.
We tried that too; routing away from the AC wires and the power trafo, but no luck so far... Does wrapping the B+ in and out wires around each other have any effect?
Post a picture of the insides of the chassis, and maybe we can make some more suggestions.
The VVRs on my Liverpool and Rocket are not near any AC. In the Liverpool, the VVR board is next to the power supply board but the B+ wires are not next to any AC wires. No noise issues at all. In my Rocket I just wired the parts right onto the MOSFET mounted by the standby switch. Again the wires are routed away from any AC wires and there is no noise.
I've installed one in a TRex I'm almost finished with. Have to wait for some more parts to come in next week till I fire it up though. This was built in a real small chassis and the routing of wires is not so good. I may have some hum issues with that one, we'll see. I'll keep you updated.
Here a picture of the chassis. One of the speaker outs is removed, and the VVR board installed in its place. The three red wires goes to the mosfet (not in the picture, sorry).
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I'm going to try to install it where the standby switch is mounted, and uninnstall the standby switch. Then i can use the original wiring to the standby switch instead of extra wiring to the VVR, just a wire to ground.
B.T.W. this is my amp we're trying to install VVR3 to.
