What OS, no five pairs of MT-200 for you sub amp! How will you live with knowing you could have more power! Just kidding, I'm sure you got enough to shake the house.
Just wanted to let you know the damned post office returned my package I sent to you saying I didn't attach enough postage? Funny thing is they were the ones who weighed the package and told me how much to pay, go figure. I'll send it back out on Monday. I wondered why you didn't receive it as the receipt said you should have had it Thursday. I may just have to go postal on them!
Just wanted to let you know the damned post office returned my package I sent to you saying I didn't attach enough postage? Funny thing is they were the ones who weighed the package and told me how much to pay, go figure. I'll send it back out on Monday. I wondered why you didn't receive it as the receipt said you should have had it Thursday. I may just have to go postal on them!
Don't underestimate 1500w worth of NJW's. Thermal conductivity ,
SOA vs. Voltage are the real players.
MT-200's have a much lower conductivity between die and slug.
NJW die is a similar size.
This V3 slew is better just by that fact , heat is dissipated out over more
"acreage". There ... my first "wine" post.
OS
Most important part.
Wine post # 2 -
Even with kapton insulators , ZNO grease will fill in microgrooves on an
imperfect extrusion. Short of polishing , a little grease does wonders.
(below 1)
Black square neoprene square under the OP inductor will keep you from
shorting out the center OP leads if you push too hard. I also have standoffs
at each end , but not mounted to the extrusion. This is another plus for
V3 , the 5 pairs support the PCB.
(below 2) Finished .... Check V+ to out and V- to out , you should see infinite Z. Also V+/V- to 0V , caps charge... then infinite Z
Tomorrow (after I burn said wine off) 😛 ... I power at my test 45V rails ,
underbias - then full 72V bliss !
OS
Wine post # 2 -
Even with kapton insulators , ZNO grease will fill in microgrooves on an
imperfect extrusion. Short of polishing , a little grease does wonders.
(below 1)
Black square neoprene square under the OP inductor will keep you from
shorting out the center OP leads if you push too hard. I also have standoffs
at each end , but not mounted to the extrusion. This is another plus for
V3 , the 5 pairs support the PCB.
(below 2) Finished .... Check V+ to out and V- to out , you should see infinite Z. Also V+/V- to 0V , caps charge... then infinite Z
Tomorrow (after I burn said wine off) 😛 ... I power at my test 45V rails ,
underbias - then full 72V bliss !
OS
Attachments
Stuffing the The BJT version we use no matched transistors.
Can we do the same with irfp240-9240?
OS, That central mje340, in the middle of the HS, did you measure it relative to the pcb or will it run with wires as Terry did it? (or maybe there is an updated HS drilling plan for V3??) Thanks
Last edited:
thimios, I matched gate to source voltage for the irfp 240/9240 parts. I think this is a good idea.
A member who lives outside the USA has asked me to order some sanken 2sc3264 2sa 1295 transistors from Newark for him.
They will be just less then $5.00 each.
Do any others want the same. Shipping to me will be free. You will only need to cover price of devices and shipping to you plus a couple of dollars for shipping materials I will need to buy.
Please PM me.
Evan
They will be just less then $5.00 each.
Do any others want the same. Shipping to me will be free. You will only need to cover price of devices and shipping to you plus a couple of dollars for shipping materials I will need to buy.
Please PM me.
Evan
Pay attention carefully.
The NJW 0281-3281/0302-1302 is so close , you might not have to
match.
On these 1302/3281 NJW's , all were 130Hfe right out of the box (tube) and
.547V vbe.
The last 0281/0302's were the same . Except for those center pairs
and when cooler , they idled at 15mv Re +/- .1 or .2mv.
At least with these devices , ON has the tolerances so refined every
semi in a tube of 20 were within a few % .
The IRFP's ... I don't know , never tested G-S on a tube of them ??
OS
While Terry's " out on a wire Vbe" will work , this Vbe really does not require it.
The fast "dynamic" thermal feedback is the driver Vbe-driver pair on the
small heatsink.
In fact , you want the main one to just provide an average of main
extrusion temperature. The smaller faster driver Vbe provides the
feedback as demanded by real world music.
OS
It lives !!
Initial results are good. I decided to throw this OPS to "the dogs"
and just connect to the big 72V (below).
First power bias was 0 (I set the voltage 1.050v before). 3 turns I was
at 12.5mV re (@60ma).
When cool , I got between 11 - 13mv Re down the rows .... evened out to
12-13mv when it reached thermal equilibrium (38C).
The heatsink has ZERO C change from one end to the other - YAHHH !
And it is the predicted few degrees celsius lower globally.
The .4C/W extrusion rating .... my room is 20C (.4 X 45w = 18) wow , 38C !
Cool !
OS
Initial results are good. I decided to throw this OPS to "the dogs"
and just connect to the big 72V (below).
First power bias was 0 (I set the voltage 1.050v before). 3 turns I was
at 12.5mV re (@60ma).
When cool , I got between 11 - 13mv Re down the rows .... evened out to
12-13mv when it reached thermal equilibrium (38C).
The heatsink has ZERO C change from one end to the other - YAHHH !
And it is the predicted few degrees celsius lower globally.
The .4C/W extrusion rating .... my room is 20C (.4 X 45w = 18) wow , 38C !
Cool !
OS
Attachments
Last edited:
scary time on #2 !
One tip - double check everything. One driver was shorted through the
insulator to the driver HS. Caught that with the meter - a burr under the
kapton.
Then I hooked it up , one output shot up to 20mv real quick . It was not
tightened down (enough).
An observation .... cycled through the warmup the first time , Re mV's
were within 3mv. Turned it off , warmed it up again within 1 mv ??
Do outputs "burn-in" ?
OK , both are a burnin' good. Music tomorrow.
Very interesting to see 5 pairs share the load with equal thermal
conductivity. No middle current hog , mV's deviations are quite
random.
OS
One tip - double check everything. One driver was shorted through the
insulator to the driver HS. Caught that with the meter - a burr under the
kapton.
Then I hooked it up , one output shot up to 20mv real quick . It was not
tightened down (enough).
An observation .... cycled through the warmup the first time , Re mV's
were within 3mv. Turned it off , warmed it up again within 1 mv ??
Do outputs "burn-in" ?
OK , both are a burnin' good. Music tomorrow.
Very interesting to see 5 pairs share the load with equal thermal
conductivity. No middle current hog , mV's deviations are quite
random.
OS
Low frequency
I wonder if a low frequency test ,let say 15Hz(scope based) can reveal the difference to low frequency reproduction between different IPS ,CFA against VFA.
I wonder if a low frequency test ,let say 15Hz(scope based) can reveal the difference to low frequency reproduction between different IPS ,CFA against VFA.
Just to clarify my question, your main Vbe is on the main HS, and the driver on the small HS, right?
Q103 is the driver Vbe on the small heatsink and Q104 is the main Vbe on the main heatsink.
I mounted Q104 on wires for one build and directly on the heatsink where OS intended on another...no real difference that I could tell.
I mounted Q104 on wires for one build and directly on the heatsink where OS intended on another...no real difference that I could tell.