Using a Variac as an attenuator.

[erigm]

I have been using the above trick as suggested. Does not sound bad running my Slient speaker as the load and a variac as the volume control. This causes oscillation with certain postions of the control on the Variac. I am running the amp at 8 ohms. I also lower the input voltage of the amp to 90 volts. Result is a very good sound when compared to other attenuators, very warm with brown sound there with the right eq settings. Just wondering if others have tried this trick?

What positions of the control cause oscillation? Do you mean the Silent Speaker is your load in parallel with the variac/speaker setup ... meaning, your variac isn't connected to the Silent Speaker is it?

What is the ohmage of your variac?

[Type O Neg]

Yes, I am using the silent speaker as the load and my variac to control the volume. I have tried it with a hot plate and a Rivera Hot sink. I prefer the overall sound of the silent speaker. No specific position for the oscillation seems to have a lot to do with proximity of the guitar to the variac. When I checked the resistance did not get a fixed reading from a DC measurement from 2 ohms to 40 ohms. If I get a change I will check it with a impedance meter. As posted, I am lowering the wall voltage into the amp to 90 volts using my UA. The amplifer section of my UA is broken so I use it for the variac feature. I am using a Marshall SL1959 that has lee jacksons mod. This is the happiest I have been with this amp in this configuration. I still have to rebias the amp to the correct bias while using the Variac. I have the gain dialed back to 5 and the master at 4 which on this amp is deafening. This is where you start to really get tone out of this amp. Eventually I will remove the master and go to a LAR/Mar or Collins type PPIMV. I wonder if EVH tried two variacs one for AC voltage and the 2nd for Volume attenuation. I read one of his interviews where that he tried a light dimmer on the output of the amp and blew the up the amp. The fact that a light dimmer uses a triac for AC control is the difference. Well I am interested in anyone that is using this config and there results.

[erigm]

Yes, I am using the silent speaker as the load and my variac to control the volume. I have tried it with a hot plate and a Rivera Hot sink. I prefer the overall sound of the silent speaker. No specific position for the oscillation seems to have a lot to do with proximity of the guitar to the variac. When I checked the resistance did not get a fixed reading from a DC measurement from 2 ohms to 40 ohms. If I get a change I will check it with a impedance meter. As posted, I am lowering the wall voltage into the amp to 90 volts using my UA. The amplifer section of my UA is broken so I use it for the variac feature. I am using a Marshall SL1959 that has lee jacksons mod. This is the happiest I have been with this amp in this configuration. I still have to rebias the amp to the correct bias while using the Variac. I have the gain dialed back to 5 and the master at 4 which on this amp is deafening. This is where you start to really get tone out of this amp. Eventually I will remove the master and go to a LAR/Mar or Collins type PPIMV. I wonder if EVH tried two variacs one for AC voltage and the 2nd for Volume attenuation. I read one of his interviews where that he tried a light dimmer on the output of the amp and blew the up the amp. The fact that a light dimmer uses a triac for AC control is the difference. Well I am interested in anyone that is using this config and there results.

If you are running your amp into the variac into the silent speaker, then the lower you run the variac the more likely you are to get oscillations because of the impedance mismatch. That's why I suggested running a fixed resistive load in parallel with this configuration (run the resistive load to the 2nd speaker jack). I think proximity to the variac and to the amp have quite an effect on noise/oscillations.

I got a fixed value of 2ohms DC resistance when checking my variac's primary, and this was regardless of the dial's settings.

I do like the sound of this, and it works quite well.

[Type O Neg]

I am running the silent speaker in parallel to the variac, it is in the second speaker jack. I am very surprised with the sound, it sounds better than any attenuator I have tried to date including the UA.

[erigm]

I am running the silent speaker in parallel to the variac, it is in the second speaker jack. I am very surprised with the sound, it sounds better than any attenuator I have tried to date including the UA.

So you have the silent speaker running in parallel to the variac, and then your regular speaker cabinet running through the variac? This would be the correct way of doing it.

[Type O Neg]

Yes that is correct. Is anyone else doing the variac/attenuator, in addition to lowering the AC/Mains input to the amp?

[vanhalen5150]

Yes that is correct. Is anyone else doing the variac/attenuator, in addition to lowering the AC/Mains input to the amp?

What exactly do you mean by a silent speaker. Are you just using the coil with no magnet from an old one?

[vanhalen5150]

Yes that is correct. Is anyone else doing the variac/attenuator, in addition to lowering the AC/Mains input to the amp?

And the variac runs parallel off than.

[erigm]

Yes that is correct. Is anyone else doing the variac/attenuator, in addition to lowering the AC/Mains input to the amp?

And the variac runs parallel off than.

No, he's saying using one variac to lower the AC voltage running into the amp, and then using another variac between the amp and the speaker for an attenuator effect.

[Type O Neg]

The silent speaker I talk about in the post is a load box made by Harry Kolbe/ Soundsmiths it performs the same function as a load resistor or attenuator.

[vanhalen5150]

Ok, I see. I realized you had 2 variacs. Sounds interesting. Guess I was wondering if a speaker coil would work by itself as a load and then run a line out/step down tranny from that. Lot of different possibilities I guess.

[Type O Neg]

You could run the speaker coil as a lod just like the Weber Mass does in its product. I have a weber mass and as little difference that I can tell prefer a fixed load like a resitor, Hot plate, or equivalent load.

[vanhalen5150]

Ya...I guess the speaker coil is a "reactive" load as opposed to a resistor which is a "resistive" load. Im not sure of the sound quality difference.
I have a hotplate and it works perfectly. Others think they suck?
However, looking at some of the diagrams in other posts with the parts...your really getting up there cost wise just to try an experiment. The Jose load box with the Jensen tran, line out, fans, etc...is still going to run you probably close to $200 I believe. I got the hotplate for $140 off ebay.

[IloveMyMarshall]

Ya...I guess the speaker coil is a "reactive" load as opposed to a resistor which is a "resistive" load. Im not sure of the sound quality difference.
I have a hotplate and it works perfectly. Others think they suck?
However, looking at some of the diagrams in other posts with the parts...your really getting up there cost wise just to try an experiment. The Jose load box with the Jensen tran, line out, fans, etc...is still going to run you probably close to $200 I believe. I got the hotplate for $140 off ebay.

Where are you getting any hot plate for 140.00 show me I will buy one for the hell of it then? The load box doesn't cost no 200 dollars you dont have to have the tranny in there rockstah doesnt and listen to his clips. My load box cost 70.00 I think maybe less Shit thats why Im here buiding shit I cant afford to buy the new stuff lol I mean its a box , two or 4 arcols resistors two jacks a pot and a resistor and wire?
Do you have any clips of your hotplate? I tried one long ago tho and it compressed my sounds so bad I almost threw it out the window but for 140.00 bucks hell I would buy one however, they are more like 200 up.
Im going through the same problem, amp sounds a hell of a lot better amp to cab then amp to jose to power amp ;-( I guess time to get on this power scaling variplex, variac stuff going on. I need to move to the country so I can crank this stuff this playing a broom levels sucks!

[dirtycooter]

yeah-move to the country-you can pee off your front porch and the neighbors are so far away they can't see your hog hanging out
Plus obscene volumes are legal