Installing VVR on Lightning clone

[yowza]

I built a Ceriatone Lightning clone and this 15 watt amp is too loud when I crank it up to where it starts to really sound good so I bought a VVR from Dana at Hall amps. I'm scaling the whole amp so I'm wondering, do I take the B+ into VVR from the first filter cap with the B+ going out of VVR to the OT and onward to the plates of the power tubes?

Also there are two resistors and two caps that I need to add in the preamp section to keep DC off the pots but there's no room left on the eyelet board. How do you add components when there's no place to put them, where do you put them, add a new board or terminal strip? I want to keep things fairly neat. Any suggestions welcome.

Thanks for your help![/img]

[angelodp]

Here is a thread that shows an off board solution.

Hope it helps

A

http://ampgarage.com/forum/viewtopic.ph ... r&start=45

[dynaman]

Yes, take the the "B+ in" from the first cap. OT is taken from the "B+ out". I recently completed a Rocket with Dana's VVR and scaled the whole amp. It worked fine.

I wound up just mounting those extra two caps right on the sockets.

[yowza]

Thanks to angelodp for the PM and dynaman for confirming what I thought to be correct!
I think I'll use a terminal strip for the preamp components just because it has a cleaner look.

Two other questions, does it matter that my Lightning doesn't have a stand-by switch, will this harm the VVR ?

Also a while back Structo suggested I try a single boot strap master volume instead of the current cross line that's in the amp now. Will the single boot strap MV still work with VVR installed?

Thanks again! I appreciate everyone's help!!!

[John_P_WI]

Yowza,

Yes, it is fine to use the VVR without a standby switch. In fact, use it as the standby by turning it all the way down - lowering the voltages.

Yes, the boot strapped master will work fine will work fine with VVR.

[yowza]

Yowza,

Yes, it is fine to use the VVR without a standby switch. In fact, use it as the standby by turning it all the way down - lowering the voltages.

Yes, the boot strapped master will work fine will work fine with VVR.

Thanks John! I do appreciate it.

I have one last question, since I have to drill a hole in the chassis to install the VVR pot and I have several possible places I can do this, are there any considerations as far as layout, noise, hum etc and where I should install the VVR pot? I'd hate to drill a hole and install the pot only to find that it's really noisy there and have to drill another hole and move it to another location. One location I'm eyeing is maybe three inches from the OT, will this be a problem?

I hope to get time to do these mods over the upcoming long weekend, I'll let you know how it turns out.

Thanks to you all! This place is a great resource!

Ed

[John_P_WI]

The VVR pot will have pulsing DC on and can radiate noise. Keep it near other similar power supply circuitry (like where a standby switch would be) and away from input grids.

[angelodp]

I positioned the VVR, on my Rocket, at the back of the chassis just into the unused area near the output selector and its very quiet. I ran the wires back down to the B+ and standby. So know it is on the back wall.

A

[yowza]

I positioned the VVR, on my Rocket, at the back of the chassis just into the unused area near the output selector and its very quiet. I ran the wires back don to the B+ and standby. So know is on the back wall.

A

Angelo it sounds like you put your VVR in the same spot I'm looking at on my chassis but on mine it's three or four inches from the OT and four or five inches from the preamp tubes so I'm concerned this might be too close to the input grids on those tubes. The amp is really quiet as it is now and I'd like to keep it that way.

My amp already has two speaker output jacks in the same area of the chassis so I may just use one of those holes and try the VVR there instead of drilling a new hole for the pot and I'll only need to drill a small hole for the MOSFET heatsink screw which is no big deal. If the VVR is quiet in this location then I can drill a new hole for the pot and move it over or use the new hole for a mid tone control that I want to add.

Thanks again!!

Ed

[surfsup]

Also there are two resistors and two caps that I need to add in the preamp section to keep DC off the pots but there's no room left on the eyelet board.

[img1000]http://chicagocadcam.com/ChrisHahn/xen10/INPUT.jpg[/img]

[angelodp]

Sure, let us know how it works for you.

A

[yowza]

OK I'm finally getting around to finishing this thing up and I have one more question. I've marked the foil on the two caps that I need to install to remove DC on pots but does it matter here which way I install them?
I know usually the idea is to install the outer foil edge to side which has lower impedance to reduce noise but I'm at a loss to know which side that is, the side going back to the input jack or the side that attaches to tube pin and is grounded after it goes through the new 1 M resistor I'm also installing?

I'm still learning here so if someone could explain the reasoning behind this solution I'd really like to understand how to figure the impedance so I can figure this out for myself.

Thanks in advance!

[yowza]

I installed the VVR on my 15 W Lightning clone and while it does attenuate the volume some, even with the VVR turned all the way down the amp is still really loud, a lot louder than I thought it would be when I crank up the volume and MV so I'm wondering what's going on.

I do think the VVR is working as the aluminum chassis gets slightly warm to the touch near the installation and when you turn VVR all the way down the amp does get quieter but not as much as I thought it would. After I installed the VVR I also switched from a crossline master volume to a single bootstrap MV which I like a lot better but the amp's still really loud with either MV config.

I thought the amp would be a lot quieter with VVR so I'm wondering how much should it attenuate the sound? Is there any way I can check the VVR and make sure it's working properly?

Thanks in advance!

[sliberty]

A properly working VVR will reduce the volume dramatically when turned all the way down. I have even had one amp virtually shut off when the VVR was on the minimum setting.

Check the voltage on B+ out pad of the VVR when the VVR is maxed, and check it again when it is at minimum setting. At minimum, the B+ out should only be about 10% of the voltage when maxed if everything is working correctly.

[yowza]

A properly working VVR will reduce the volume dramatically when turned all the way down. I have even had one amp virtually shut off when the VVR was on the minimum setting.

Check the voltage on B+ out pad of the VVR when the VVR is maxed, and check it again when it is at minimum setting. At minimum, the B+ out should only be about 10% of the voltage when maxed if everything is working correctly.

I checked the VVR with my meter and the B plus out when maxed is around 440 V and around 34 V when VVR is turned all the way down so it does appear to be working but the voltage reduction doesn't translate to much volume reduction. Maybe this amp is just destined to be loud.

Any thing else I can check or is this just the way it is?

Thanks!