high power, class a/b and, heavy metal

[RogerG]

My first post about a high power mono block went well. Thanks to all. It did help. But I have to ask a few more questions.
I know that 500wrms@8ohms is a load of power. But it's done everyday by many. My moto is, If it's man made, this man can learn to do it!
Some local hifi techs that I know suggest taking a working amp design, maybe 300w/8ohms and altering it for the power I'm looking for. The names Marshall and Peavey have come up.
This seems like a good idea to me. If I know anything here it's that I don't know enough to start from scratch. But reengineering a working design has got to be tricky.
Also, I'm trying to figure in to all this that I listen to heavy metal. The music is distorted, low frequency and, should be played loud!

Do any of you think it's better to mod a working design?
Does the circuitry class matter?
If so, why?
Does my choice in music affect the design?
Any info helps, so please share it with me.
Roger

[AndrewT]

Hi,
go classAB, some others might recommend the new classes for a bass driver.
Do not consider ClassA- too hot and at your voltages you must keep the output cool so you cannot go Hi Bias either.
The SOA of the output is seriously affected by transistor case temperature forcing ultra heatsinks into your design. Probably fan cooled, the fan noise might not be a problem after a couple of nights. You will have gone deaf by then.
good luck

[ChocoHolic]

Hi Roger!

I guess that in most comercial designs you would need to change the
power supply..... transistors with required voltage rating (input and VAS) and higher voltage rating + power in the output stage....
power... adjust all bias settings accordingly....
...adjust frequency compensation....

One convinient point:
You can use the mechanical set up and may be some protections as
delayed speakers relay ....

But by the way: For your ears the difference between 300W and
500W is just a small step. Just 2.2 dB. Not worth much efforts!!

But you could pick a working amp which delivers 2 x 300W into 4 Ohms and bridge it to a mono 600W/8Ohm mono block...

My
....be careful, you might loose some fun after hammering your ears to deafness....

By Markus

[ChocoHolic]

@Andrew:
... I see you had the same concerns about Roger's health...
...overlapping answers...

[RogerG]

Originally posted by ChocoHolic
@Andrew:
... I see you had the same concerns about Roger's health...
...overlapping answers...

Thanks for the health advise, guys. Do you handle bad backs, too? Obviously kidding!
Really, the input is great. A/B class did seem to have advantages. Less heat being one of them.
I posted about this when I first joined the site. For ideas on what it take to do it. I know that 300w will be nearly as loud as 500w. And I'm kicking around another suggestion that I go with 400w/8ohms. I'm just trying to match my driver ratings as close as I can.
I am worried about my choice in music. I need an amp I can lean on pretty hard without hurting it. But it must be able to reproduce what I put into it. Which will be very heavy and distorted anyway. Will my love for metal make an amp design impossible?

Roger

[cunningham]

I would think that you might need some headroom with that type of music. I would suspect also a faster slew rate would help keep up with the harmonics (or distortion)generated in Metal music. This distortion is specific and can be easily "distorted". Faster slew would certainly keep up with the high freq.'s better. Too much freq. compensation and it may sound muddy.

I would buy an amp that will not blow the speaker drivers, i e rated less. Speaker diaphrams don't move linear after about 60% anyway. Might even under-rate the speakers a little for these tunes.

Avid Tool listener...

Chris

[RogerG]

Originally posted by cunningham


Avid Tool listener...

Chris

Thanks Chris! BTW check out At Gun Point from Chattanooga. Great local metal act and very cool guys.
Roger

[darkfenriz]

in HM you have plenty of distortion of guitars, sometimes bass and even vocals and it can 'mask' the distortion of your amp at cliping level. Remember to use speakers with high-power tweeter to avoid distortion-induced breakdown. Sorry for hurting language.

[demogorgon]

hmm, your imense power requiremets got me thinking, Mr.Elliot has some nice projects out on his page, this being a 500W sub amp, but there is nothing that keeps you from using this as a fullrange amp..

http://www.sound.westhost.com/project68.htm

the output devices used are fairly fast devices from on semi, i see no reason for this amp not to have a decent slew rate..

it may be a possibility?

-marius

(immortal - Wrath from Above)
Metal Roxx

[Peter M.]

What about a good tube amp?

Tubeamps sounds absolutely fantastic on heavy metal.

Regards,
Peter