Suitable Driver Subs....

laatsch55

laatsch55

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Sir Joe, If I could figure out how to mount them, would an MJE 15032 be suitable for WOPL projects???
 
laatsch55 said:
Sir Joe, If I could figure out how to mount them, would an MJE 15032 be suitable for WOPL projects???
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Oh boy, here we go... :banghead:

Joe and I just had a long drawn out conversation about the MJ15024's, Lee. Joe said that the 15024's are fine for predrivers with 21194/21196's for outputs. Confused the heck outta me, because we've had this question surface a few times, and you guys were always telling me that 15024's were no good. When we cleared the air, Joe and I, it was because he was thinking I meant to use 15024's for both predrivers and outputs. Furthering the confusion was remember you sent me ole "SN1" populated with 15024's for predrivers and 21196's for outputs (yielding another "wth??" coming from my confused mind.. heheh).

So... to put it out there... MJ15024's can be used for predrivers, right guys? As long as you're NOT using them for outputs as well?? NOW.. that isn't to say that the 410's aren't still the better choice, because sound-wise to my ears they are. But.. at least it's good to know the 15024's can be used.

Lee this is a GREAT opportunity to put that analyzer to good use! I'm curious to see a good comparison between 410's and 15024's for predrivers, and with 21194/96's for outputs... AND.. on both the 400 and 700. Now THAT would really settle it all, eh? And maybe we can try some others as well to get a good idea going forward what the pro's and con's are, at least objectively...
 
Already did that on James' 400. The noise floor was twice as much on the 15024's as the 410's. You also might check out the number of the tranny I posted....it's a plastic cased TO-=220
 
No, check that, I compared the 15024's to the 21194's as outputs with both being driven by the 410's. The 24's were much noisier, and the 94's sounded better.
 
laatsch55 said:
No, check that, I compared the 15024's to the 21194's as outputs with both being driven by the 410's. The 24's were much noisier, and the 94's sounded better.
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Yeah, I'd like to see them as predrivers with both 194/196's as outputs... then compare with the 410's in as predrivers with the same two tests (194's as outputs.. then 196's as outputs). Maybe a listening test too for that "subjective" opinion.. heheh

I think that some tweaking on the zobel thrown it might be interesting too?
 
I'm thinkin some data like that would be very useful....
 
jbeckva said:
Yeah, I'd like to see them as predrivers with both 194/196's as outputs... then compare with the 410's in as predrivers with the same two tests (194's as outputs.. then 196's as outputs). Maybe a listening test too for that "subjective" opinion.. heheh

I think that some tweaking on the zobel thrown it might be interesting too?
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I've always been very interested in the Zobel network of the PL. This could be a very interesting thread.
 
laatsch55 said:
No, check that, I compared the 15024's to the 21194's as outputs with both being driven by the 410's. The 24's were much noisier, and the 94's sounded better.
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What about comparing 194's to 196's as drivers for noise and overall SQ rating? Done that comparison yet?
 
Just to put a finer point on this, I did not say the word "fine" as in work fine.

What I did say was this...

"The RCA410 is 2X slower (2MHz) than the 15024 (4MHz) and is a better candidate because it is truly dominant. The 15024 is 4/5s as fast as the 21196 (5MHz) so it is not as clear as the previous case and will operate but with lower phase margin.

The 15024/21196 will work but is more marginal than the 410/21196 combo. "Redacted text"

If the oscillation occurs, it is at multi megahertz. Not really an audible problem. It is a power dissipation issue and a damage issue "redacted text"

The configuration and issue is the same whether a 400 or 700. The lower half of the quasi-comp setup is the same. Just more final outputs in the PL700 (5 vs 3 per half)."

The real issue we are all discussing is that the RCA410 was a great device for the application and that the source(s) for these is drying up. They do come up on Ebay from time to time. Baby the RCA410s that you still have is a great recommendation.

The other thing I will be looking at if I find the time is "much faster" predriver devices used in conjunction with the relatively slow MJ21196 as final output.
 
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Joe on the 6546's I have, I'm showing an hfe of 17-20. Motorola devices, 7839 date code.
 
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OK, let's start from square one--------What attributes are we looking for in the drivers for the WOPL's???
 
First lets get straight on the nomenclature.

Pre-Drivers are classic RCA410 location. Typically Q11 and Q12 in the PL400.
Drivers are the classic PL909 location. Typically Q13-Q18 in the PL400

Pre-driver demands are minimal.
Vce = 200V min.

Slow, Ft less than 1/2 of the output device. Or alternatively 2X it.

Low current gain (this contributes to the low Ft).

Lower noise is better (hardly ever specified, determined by measurement)


Driver demands are substantial

Vce>= 250V

Large SOA, especially ability to sustain more current in the 10-50msec range at 200V (160V for the PL400) is important. The more the better. The 21196 is well suited in this regard in that it will safely sustain 1.5A for 50msec at 200V (this is the half wave time for a 10Hz signal).

Ft >= 2X the predriver is ideal, the more the better. Typically minimum 4MHz is acceptable.

Lower noise is better (hardly ever specified, determined by measurement)

The more current gain, the better. The 21196 has hFE between 50-75 at 3A.







What I mean by bounded Ft on the 2N6546 is that it specifies a minimum of 6MHz and a maximum of 24MHz. It is unusual to find a transistor with the upper end of Ft specified. Usually just the lower minimum is specified.
 
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Now that you mention it I have never noticed an upper figure. Those figures fluctuate with collector current correct??
 
The 2SD555 still stacks up pretty good. Notice the hfe gain grouping. I have some q's. I'll run some by the Sencore and see if they're really 100-200.
 

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laatsch55 said:
The 2SD555 still stacks up pretty good. Notice the hfe gain grouping. I have some q's. I'll run some by the Sencore and see if they're really 100-200.
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Hi Lee

Not without knowing the SOA characteristics Lee. Additionally the TYPICAL Ft is 4-7. Cannot plan anything around a typical spec.

BTW, I replace Japanese transistors on every chance that I get :-)
 
The q's are consistently over 100, the S's are 30-40, the R's 40-60
 
Gepetto said:
Hi Lee

Not without knowing the SOA characteristics Lee. Additionally the TYPICAL Ft is 4-7. Cannot plan anything around a typical spec.

BTW, I replace Japanese transistors on every chance that I get :-)
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But it does meet the minimum spec??
 
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