Burning Amp BA-3

[coils]

3. how many watts exactly it will produce with 12pcs irf240 per channel

Hi wengtech, I made a 12 pair ("6 deep") single ended burning amp.
Mine has 21.7 volt rails, and produces 20.6 watts into 8 ohms just before clipping. If you do not use R219, you will need a lot of heatsink.

cheers

 

[Zen Mod]

6 deep means 6 pairs deep , or 6 verticals deep ....... not pieces


so , 3 deep is having 6pcs per channel

 

[coils]

6 deep means 6 pairs deep , or 6 verticals deep ....... not pieces


so , 3 deep is having 6pcs per channel

I agree ZM. My build uses 12 mosfets per channel, thus "6 deep" as per Papa.

cheers

 

[Russellc]

yup

replace them

Ok, surgery complete, I found same caps, 105 degree 35 volt version of the Panasonic caps I did have, except in 35 volt versions. The 50 volt version was either quite larger, or crapier specs....thus I stuck with 35 volt version.

Russellc

 

[Rothor]

Would appreciate some advice before ordering a new toroid. I've got two 500VA 24v toroids that I had planed to use for a F5t, but have changed my mind and am putting together a BA-3 instead. Is it any use trying to bring down the voltage of these transformers to 18v, so that I can run at a higher bias in a 4U chassis, or would I be better of getting a new 18v toroid? I'm planing to us the Universal Power Supply from the store...

Appreciate any suggestions!

//Ronny

 

[6L6]

Total bias is better thought of as heat, not voltage, and you will hit the limit of excess heat in your heatsinks before any other limiting factor...

Make the BA-3 with one of your transformers. The higher voltage has some good advantages.

 

[Rothor]

Thanks 6L6!
I knew heat would be the main problem, but sometimes you guys have some amazing tricks up your sleeves...

What would those good advantages be? Maybe I should consider getting the 5U chassis instead? Could
come in handy if I'd decide to build something else in the future...

 

[6L6]

The good advantages is simply more output power.

If you have not bought a case, yes, strongly consider the 5U. As Nelson says, you can never have too much money or heatsinks too big. Do make sure it fits your space, it's fairly large.

 

[Rothor]

Size and WAF were the reasons for looking at the 4U. On the other hand, size is mainly a matter of planing, and acceptance a matter of negotiating and geting used to... =D

 

[Russellc]

Would appreciate some advice before ordering a new toroid. I've got two 500VA 24v toroids that I had planed to use for a F5t, but have changed my mind and am putting together a BA-3 instead. Is it any use trying to bring down the voltage of these transformers to 18v, so that I can run at a higher bias in a 4U chassis, or would I be better of getting a new 18v toroid? I'm planing to us the Universal Power Supply from the store...

Appreciate any suggestions!

//Ronny

Just go for it. I did the same thing, wantrd to build turbo F5, then went with BA-3. I ended up with 31 volt rails from my 1000VA 24+24 volt trany. So was 6l6's build, any higher and you will need cascode for sure. Surprising jump in power.

Russellc

 

[Rothor]

Found a pair of broken Bonnec Alto for sale. Does anybody know if they could possibly handle the heat from the BA-3 with 18v toroids? I was thinking of maybe building them as two separate mono amps if one is not enough, if that could work? Totally new to this, so any suggestions are appreciated!

 

[Zen Mod]

search for Papa's palm rule

then make a test

 

[Rothor]

Was hoping to get a hint before I bought the chassis and built the amp...

 

[Rothor]

I've never even heard of the brand before, just thought it looked cool.

 

[Hikari1]

I wouldn't put my hand on that with a BA-3 inside it.

 

[Zen Mod]

funny looking , I would like it in my living room

Rothor - give us some link to amp data , and then maybe you'll get hint

 

[Rothor]

The specs I found are:

Class A/B 100W 8 ohm/200W 4 ohm
Class A 3W

Consumption 30 / 940VA, 55A peak

Gain 28,5 dB

Weight 26kg

 

[Zen Mod]

if that is made for any amount of prolonged time to work in higher power area , heatsinks are adequate for BA3 monoblocks

in your boots , I would try

no pain , no gain

 

[wengtech]

hello again,
i have 4pcs Rcore single 32vac 180va each.
(that will be 2x32vac 360va for one channel)
if i separate the supply for gain stages.
is it okay to supply for the output stages?

thanks.

 

[6L6]

There's no advantage in doing that. (Other than using up your transformers)

32VAC will rectify into about 44VDC, minus about 2 for the diode drop leaving 42V rails.

As the BA-3 output stage has no gain, you will never hit the rails, as the output voltage cant be higher than the rails of the gain stage.

Buy 24VAC transformers. OR make an active regulator like in Zen Variations 3, but that adds to your total heat footprint.