Do output transistors have their own "sound"

[ksrigg]

Just wondering, if there is a difference in the way different driver and output transistors "sound". I know in some case the specs are identical, and in other cases not, but they will "work" in a given application. But, is there a difference in the sonic signature of different transistors? Say a MJ 15024 and a MJ 21196....I know we are using one for the outputs in a Phase Linear 400 and the other as outputs in the 780B. IN MY EXPERIENCE, the output of the 400 is just "sweeter" from top to bottom, non-fatiguing, and just very "nice". While, TO ME, the outputs used in the 700B just sound a little more edgier, or more solid state sounding.......if this makes any sense to anyone..and I know the circuitry in the 700B and the 400 are not the same, and to have a valid comparison, a person would need to have two 400's or two 700B's all set up as close as possible to being the same to really tell the difference......

But this has interested me for some time, and wondered if anyone else "heard" the difference I am talking about. Kevin says he hears it, and knows exactly what I am saying...and this may not (probably isn't) measurable.....Just wondered what other member's ears and analysis is telling them...

Is there a way to quantify these observations? Is there any difference in the FR or THD&N of these two (and other) transistors?

Just interested in anyone's thoughts. I know Dr. Mark made the comment that, after converting a Phase Linear for me and hearing the difference, was ordering new MJ's for his Phase Linears...after running original transistors in them for years, so Mark must have heard something, and I think the specs for the old PL transistors was the same as the new On-Semi devices...so what do you all think?

 

[Skratch]

IMHO the 400 is a better sounding amp than the 700. They both put out a lot of power power. If you have a highly efficient speaker system the 400 blows away the 700 in the sound quality. I have a 400 with the XPL 910 outputs that is almost as clean as any of my tube stuff, But I have White Oaked the rest.

 

[laatsch55]

Ah Skratch, tell it like it is!!!!

Sutton, I believe there is something to that. I think the 21194's are the best sounding of the bunch, with 15024's as drivers. mlucitt thinks the 410's as drivers sound better. It's a big wide world out there, big enough for all of us---ain't that cool??

 

[laatsch55]

At one time Jer's 700 sounded better than anything that had been through the cave---period. 400, Spec 2, PERIOD. I hope to duplicate that again.


Have to back up here a bit. Gibsonian's was a VERY nice sounding amp. he optyed to have the pots bypassed permanently and that made a big difference.

 

[laatsch55]

The specs are NOT the SAME for the old PL outputs and the new On-Semi outputs. In fact if you look at the datashe3ets for the 21196's they actually quote a harmonmic distortion spec, one of the few you will see.

 

[ksrigg]

Would it be possible to sub the transistors in the 700B, using the On Semi drivers and outputs typically used in the 400? Or are the voltages so different that it is not possible?

What is your favorite combo of drivers and outputs for the 400? And then for the 700B? What are you using in each Skratch? Lee? Mark? Joe? Soundude? Anyone else who cares to answer....

 

[kevin]

This is a good subject..... OK.... Could the 700 ever be made to sound like the sweet, soft , clean 400 ???? What makes them sound so different. Yall know I LOVE both my amps..... Could there ever be an amp as sweet as the 400 but as big and loud as the 700 ???? I think in a round about way thats what Sutton is asking ???? Maybe ???? Kinda ???? LOL.......

 

[speakerman1]

This is a good subject..... OK.... Could the 700 ever be made to sound like the sweet, soft , clean 400 ???? What makes them sound so different. Yall know I LOVE both my amps..... Could there ever be an amp as sweet as the 400 but as big and loud as the 700 ???? I think in a round about way thats what Sutton is asking ???? Maybe ???? Kinda ???? LOL.......

I haven't heard the WO board. I know by changing the caps in my 700B it doesn't sound as SS as it did when it left here. Your mileage may vary depending on your driving habits. LOL That is my system though.

Larry

 

[kevin]

Very true..... I've always been told I drive to fast !!!!!

 

[speakerman1]

LOL Me too. 50 on my scooter is fun though.

Larry

 

[ksrigg]

Exactly what I am trying to ask Kevin. Good....you are totally in agreement with me. Great review of the two amps too....Great...

 

[laatsch55]

Yes, yes, and yes. But a severe mod of the 700 must take place. On most of my conversions most of those have been done. the rest would be no pots, period. Direct wiring to the board from the inputs. The .33uf caps on the back wall. The back to back 1n4148 diodes to quell static discharge. AC routed to the tranny side, careful rebundling of ALL WIRES and rerouting to keep low signal away from ac and dc being twistedpairs. It can be done, not cheaply as a lot of labor is involved, and you would have a 400 on steroids, not a true 700 as your options would be limited.


Always a tradeoff , ain't there.

 

[laatsch55]

My favorite combo on the 400 is MJ15024's as drivers. MJ 21194's as outputs.
700--MJ15024's or Mj2194's as drivers and MJ21`196's as outputs.

That being said, a very sweet 400 left here on a local deal that had 2SD555's as outputs with MJ2741's as drivers.

 

[ksrigg]

I just love the sweet clean sound of the 400. And really, it probably is enough power....(OK, I'll go along with myself for now), especially if I were to bi-amp. I think my next experiment will be to bi-amp the Line Arrays using two 400's and see what we get. Curently I have ane 700B driving them..I haven't even bi-amped using a 700 for the mid-woofs and a 400 bot the planars. I'll bet either one will be great, especially in that the sweetness of the 400 will be heard through the tweeters, and the brute force and poser will be rocking the mid-woofers. I've already been able to get the mid-woofers to "clip" using just the 700B driving the speakers. How about you Kevin? Same thing? I didn't leave the volume there but for a "pop" or two, so I didn't damage the speakers. I really think they were over excurding....

When the 700B from Bill arrives, it is full of the 2SD555 outputs, so there should be 20 to play with. They are now discontinued.

What is the general consensus for other thing Bob Carver....like the M-500 the Sunfire stuff....and other designs...

 

[laatsch55]

Don't know but Gibsonian has heard a bunch and prefers the Series I's. we are fixin to see if the Carver TP2400 can hold a candle to his earlier stuff.

 

[kevin]

Sutton.... Yes I have heard mine "pop" thats why Ive said a couple of time that for the first time ever I feel like I got enough power !!! But.... Thats banging the meters in the red pretty hard !! Ya really never do that much in normal listening. Lee.... I kinda understand everything you said.... lol... Let me ask this.... What do ya mean by the caps on the back wall.... Does that mean you would have to move them from where they are ????? I really dont know how to word my next question....... Are you saying that the 400 has the sweet, warm sound because it has less in it and does not have as much high voltage running around in there ?????

 

[laatsch55]

Kevin it could be a multitude of things, less outputs means less buss bar wiring, lower rail voltages, less emi, and rfi because of that. The caps on the 3 terminal strips were used to strip any induced rfi and emi that the output wiring picked up from the board to the outputs, I have not left them on all 400 builds. Did not think it was necessary, and probably wasn't in most cases but is definately needed on the 700 because of the more hostile operating environment. AKA more rail voltage, more wiring that acts like an induction antenna.

 

[kevin]

Would ya loose much power to build a 700 that way..... Looking forward to seeing what ya think of that TP2400.... Didnt it weigh alot less than a 700..... In my mind.... '' WHAT LITTLE I GOT'' I would think it would have weigh more to have that much more power...... Quess not ????

 

[ksrigg]

Kevin.....when you hear the "pop" turn the amp down. It will cause damage to the drivers ultimately, so if your preamp is at say.... -5 db when you hear the "pop", make it a rule you never go above -6db or whatever. I think the drivers were rated at 50 watt peak and there are 12 of them, they should be able to take 600 watts..but the Phas Linear 700B probably is capable of delivering 1,000 watts PEAK power per side...especiall with the 22,000 uf caps these babies are now sporting...With the little 9,000 uf caps, the amps probably couldn't deliver this kind of peak power. Lee and Joe can probably more precisely tell you the capabilites of the amp, as I am talking strictly out of my buttcoks....I just don't want ya to damege those mid-woofers. We won't like it if we have to replace thos drivers. That black goop we used to seal the drivers has now turned into something more like a tarry glue....

The specs on the 2400 Lee bought are freaking amazing. I think it uses two outlets, each one with 20 amp service. One of Bob Carver's early amps actually used the transformer out on the utility pole as the transformer for his amp. It made the amp fit in a coffe can and I think it weighed something like 5 pounds.

With the 2400, I think Lee may have finally found something that will make his speakers go "pop".

 

[kevin]

SSSHHHHUUUUUUU !!!!! Glad you told me that Rigg.... When they went '' pop '' I was turning mine up a little hoping they would overcome that little noise.... lol.... Now I know Im not the sharpiest tool in the shed but I did know to back off a little when they did that.... Yea.... That was cool about that 2400 using two plug-ins..... I dont think it will ''pop'' Lee's speakers though...