power scaling for Laney vc15?

[bsmco]

Has anyone added power scalig to a Laney vc15?

thanks :RoCkIn

[mooreamps]

I don't think so. Most electronic power brakes are designed for single-ended power amps, including mine. I have a circuit for push-pull, but it's not been brought up yet.
-g

[bsmco]

How does this work on the Suhr Badger?

So this circuit should work on an L20H? It is parallel single ended. 4 el84s for 20w.

thanks :)

[bsmco]

I heard about an article in Vintage Guitar that talked about using a Variac device to control the amount of voltage that is sent to your amp. This is supposed to work like power scaling except that it changes the voltage for the entire amp instead of just the poweramp. What are the drawbacks of using such a thing? I think this may be worth a try!

thanks :JAM

[tlpruitt]

I believe the drawback of using a variac to lower the output of the amp by lowering the overall voltage powering the amp as a whole is that when you lower the overall voltage to the amp you are also lowering the voltage going to the heaters in the tubes (which are supposed to get around 6.3V) and when the heater voltage gets too low the tubes don't work correctly and the amp starts to sound like doodoo.

The article in the recent Vintage Guitar magazine describes the drawback.

-Tim

[bsmco]

Does the variac provide the same functionality as power scaling except for the heater voltage? Is there a way to keep the heater voltage the same as you lower the voltage?

thanks :crazy

[mooreamps]

Does the variac provide the same functionality as power scaling except for the heater voltage? Is there a way to keep the heater voltage the same as you lower the voltage?

thanks :crazy

You would have to put the filaments and pre-amp tubes on one power supply, and then the High Voltage for the power tubes on the variac power supply. Be better to use a power scaling circuit.

-g

[John Phillips]

I believe the drawback of using a variac to lower the output of the amp by lowering the overall voltage powering the amp as a whole is that when you lower the overall voltage to the amp you are also lowering the voltage going to the heaters in the tubes (which are supposed to get around 6.3V) and when the heater voltage gets too low the tubes don't work correctly and the amp starts to sound like doodoo.

The article in the recent Vintage Guitar magazine describes the drawback.That's exactly correct and why an external Variac is not useful for any significant volume reduction. It may be useful to change the tone and/or feel of the amp, and you may get a small reduction in volume as well, but no more than 1 to 2dB before you're outside the range it's safe to run the tubes at, where you will get an odd (not good) tone and possible tube damage - typically you can drop the voltage by no more than about 20% before this happens.

The other disadvantage is that - even if you use an internal Variac with the filaments on a separate supply - it lowers all the HT voltages in the amp, including in the preamp. This will not only change the tone, it actually reduces available gain.

Power scaling can solve both problems by only reducing the voltages where you want them to be, usually just the power tubes or the power tubes and phase inverter, but not the earlier stages of the preamp.

It can be applied to any amp AFAIK, definitely including push-pull, both fixed- and cathode-biased. I did a conversion recently on a cathode-biased push-pull amp, which worked very well and was actually quite simple.

[HCStraub]

Has anyone added power scalig to a Laney vc15?

thanks :RoCkIn

Go Here and ask: http://www.powerscaling.com/community/index.php

Powerscaling is a LondonPower trademark and they are the ones that promote the circuits. They have a few options amps like yours. The guys on the forum can steer you to a good solution and help you find someone to install it.
FWIW, I put a powerscaling circuit in an 18watt amp (cathode biased)and it wasn't too bad of a job. Your amp will be more complicated, but should be doable. It won't be cheap, it takes some time to do.

[bsmco]

thanks for all the input! it would seem that a power scaling circuit would be the way to go. it may take a while but i'll post some clips when i'm finished.

thanks ;)

[phsyconoodler]

The biggest problem would be installing power scaling in a PC based amp like the Laney.The boards in Laneys are fragile at best.
I would much rather hand-wire the laney and then power scale it.Then you would have a nice amp.I like the sound of the 15 watt Laneys' but mine was in the shop so many times I had to give it back to the store.It never ran long enough to enjoy it.