Why don't more amps do this...?

[Jeremiah]

http://www.ashdownmusic.com/bass/det...n=valve&ID=267

Ok, so it's a bass amp, but the bit I'm looking at is this:

"The CTM 300 also features user adjustable bias for each individual power tube which can be set by engaging the bias mode of the dual function VU meter on the front panel."

User adjustable bias - no need to open up the amp and fiddle around with bias probes and test points, potentially exposing yourself to dangerous voltages. Seems like a no-brainer except that it must add to the cost, so why don't more amps have it?

[ItsaBass]

Re: Why don't more amps do this...?

Most amp makers probably don't want users to be adjusting the bias. Also, I don't think it is something that most people are even aware of, or would ever want to adjust.

Here's a somewhat related article by Randall Smith at Mesa: http://www.mesaboogie.com/US/Smith/biasadjust.html. A lot of self promotion in there, but there is also something technical to take from reading it.

[GuitarDoc]

Re: Why don't more amps do this...?

I'd be tempted to buy that amp just for its features.

[Toe-Knee]

Re: Why don't more amps do this...?

All of my amps have external bias test points and adjustment. I think it should be a standard feature.

I do however give people documentation describing in detail how to correctly bias the valves and a few recommended settings for different valve types. I also verbally make sure that people who buy my amps aren't retards too

[Kam]

Re: Why don't more amps do this...?

All of my amps have external bias test points and adjustment. I think it should be a standard feature.

I do however give people documentation describing in detail how to correctly bias the valves and a few recommended settings for different valve types. I also verbally make sure that people who buy my amps aren't retards too

Do you have a website for your amps or anything, dude?

[Toe-Knee]

Re: Why don't more amps do this...?

Do you have a website for your amps or anything, dude?

Nah. When I say my amps its more whatever I fancy building for the knowledge and experience that I then sell on just to cover the costs and to start something new

there is a bit of info on www.diy-audio.tk but that's mainly SLO style builds.

Once I've moved this one along i'm going to try and figure out the uberschall

[Mr 9finger]

Re: Why don't more amps do this...?

Nah. When I say my amps its more whatever I fancy building for the knowledge and experience that I then sell on just to cover the costs and to start something new

there is a bit of info on www.diy-audio.tk but that's mainly SLO style builds.

Once I've moved this one along i'm going to try and figure out the uberschall

You do that.....and keep me in the loop on it.

[Toe-Knee]

Re: Why don't more amps do this...?

You do that.....and keep me in the loop on it.

I shall do. I've been doing some research on it for a while. I'm about to start piecing together a schematic from the hundreds of partially correct ones and see what happens. It will probably take a while though but I find it's best not to rush these things.

[glassman]

Re: Why don't more amps do this...?

Lots of amps have externally adjustable bias...Ampeg SVTs have it on the back along with LEDs that tell you when you are correctly biased. An incorrectly biased SVT can tear itself apart.

Most newer Marshall's also do, as do some Peaveys though their range is limited to stay within a safe range.

The main issue is with the warranty...beyond that, if you include a "user" adjustment on a piece of equipment that is capable of being set in a range that can do harm to that equipment...somebody's gonna do it. Those same people are also the ones that blab that your stuff is junk because it burnt down on them.

[GuitarDoc]

Re: Why don't more amps do this...?

Awesome dude, wish I had the knowledge to do that. Sounds like a lot of fun.

[Toe-Knee]

Re: Why don't more amps do this...?

Awesome dude, wish I had the knowledge to do that. Sounds like a lot of fun.

It's something that has a pretty steep learning curve but after the initial hump so to speak it's something that you learn as you go along whilst being cautious and thinking about everything twice initially.