revolutiondeux.blogspot.com Thanks Sds1! That is a thorough source. I'm not up to speed on Mosfets and especially how to decide if one is a proper substitution and none of the mentioned ones in that link are available from Antique Electronic Supply, where I'm putting together an order. You've done plenty, but It'd be greatly appreciated if someone in the know would pipe up.Excellent resource here:
Voltage Scaling in Amplifiers - Power Scaling / VVR
Dana Hall's VVR3 PCB kit. Power Scaling (a London Power trademark) and VVR, which stands for Variable Voltage Regulator, (Dana Hall of ...
You're welcome. Those MOSFET's are end of life and AES doesn't have a great selection anyhow, you'll need to take a trip to Mouser for these. Let's see what we can find...
it sucks to have to pay for shipping again just to get one replacement!
marshallforum.com An approach that doesn't involve (active, digital) semiconductors is the resistor/inductor-based attenuator, downstream of the output jack. There's a very popular DIY version of one designed by one JohnH from NSW Australia, and published on the Marshall Forum:
It has a fairly large following, and that thread is currently up to nearly 250 pages.Simple Attenuators - Design And Testing
Background Passive attenuators are wired between the amp output and the speakers. Their function is to absorb most of the output power of the amp, feeding a smaller amount to the speaker itself. This allows the amp output stage to run at higher power, letting the glorious tone of a good valve...
Wouldn't recommend this.
It's not. It's power scaling.
Digital? Why should OP avoid semiconductors?
The Mosfet is in the signal chain, adjusting it changes how the amp operates and modifies the signal.
Is this future build going to be cathode-biased or fixed-biased?
I would not e.g. consider a dropping resistor in the B+ part of the signal chain. A VVR is more akin to that than a low or high pass filter.
That's an important question! I'm planning on cathode bias which it sounds like that makes it easier to use VVR.
A stiff PS will make an amp sound differently than one that sags. At low levels you may not hear any difference between them but cranked you would. The same goes with an amp with a VVR. At low levels you man not hear much of a difference but crank it and you will. If you did not know what circuit is in the amp and the VVR control is called something exotic like 'saturation' you might have a hard time deciding if it was in the signal chain or not.
I'm no expert but that looks good. It certainly applies to exactly what I'm thinking about. Where did you find it and or are there any other recommendations for applicable mosfets?
I like how so far this thread has made it reasonable to be not totally decided on any one way of solving the problems that I create.One source for both NTE 2973 and NTE 2372 that still exists (NOS) is eBay.
Nte 2973 for sale | eBay
Get the best deals for Nte 2973 at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!www.ebay.comNte 2372 for sale | eBay
Get the best deals for Nte 2372 at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!www.ebay.com
As I understand it, the whole VVR thing is about attenuation, in the end, is it not? An approach that doesn't involve (active, digital) semiconductors is the resistor/inductor-based attenuator, downstream of the output jack. There's a very popular DIY version of one designed by one JohnH from NSW Australia, and published on the Marshall Forum:
It has a fairly large following, and that thread is currently up to nearly 250 pages.Simple Attenuators - Design And Testing
Background Passive attenuators are wired between the amp output and the speakers. Their function is to absorb most of the output power of the amp, feeding a smaller amount to the speaker itself. This allows the amp output stage to run at higher power, letting the glorious tone of a good valve...
