Do output transistors have their own "sound"

[laatsch55]

That is not my objective. The Jamborees are a K-Horn on steroids with a folded horn bass bin WITH 2-15" CRITES WOOFS IN THEM. They would eat up that 750 into 8 per side pretty easily. Joe says it has a switching power supply which means noise and reliability issues, but I just couldn't resist. It will be interesting to see if it can last a bit in "The Pit of Despair..."

 

[laatsch55]

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 ????

No Kev, you would not lose power, you misunderstood my 400 on steroids remark. I was thinking it could be as quiet as a 400 with the power of a 700. AND I"M NOT convinced a 700 series I done right is noisier than a 400. haven't quantified that yet, but feerl 'm close to being able too!!

 

[laatsch55]

More outputs-more common mode conduction?? more outputs--more crossover notch distortion??

 

[wattsabundant]

When they were available, I used a lot of 2sd555's. They were very reliable, but the amps seemed more likely to oscillate. I had a 700II that burnt up the R/C network with 555's but was fine with 21196's.

The difference in sound from one amp to another could be oscillations. I've never listened to one that oscillated on the bench. The only way you know if it oscillates is to see it on a scope.

 

[ksrigg]

Yppers, that "pop" is the speaker drivers "bottoming out". That is a very bad thing. Turning the amp UP could have been even worse..You could melt the voice coil...or other NOT GOOD stuff. Just make sure you know to not push the speaker that hard...It will cause long term damage and will result in our having to replace the drivers...

Can't wait to hear aout Lee's new acquisition. I'll bet it will be able to make his speakers go "pop" if it is optimized with Joe and Lee's knowledge...

 

[ksrigg]

Culd the MJ 21194's be used as outputs ina 700B? Or are they strictly a driver transistor? I know we are using NPN devices for drivers and outputs: I'm just trying to determine what you already probably have.....find the best combo for a 400 and a 700.....and I know it is subjective as all heck.. I just know I love the sound of the 400 more than that of the 700, and want to try to sweeten up the 700 a bit. I'm getting ready to place a Mouser order, and wondered what might be a good combo to order.......I don't have enough of anything ON HAND .....

I do have enough 21196's, 15024, and probably enough of the RCA devices from 400's and 700's to do some different drivers.... With the analyzer have you seen anything unexpected...Have you looked at transistors per se, to determine the qualifications...of each device? Wonder about the RSD devices...Any help...really apreciated..

 

[ksrigg]

Anyone read this?

http://sound.westhost.com/project3a.htm

 

[laatsch55]

Yep years ago.

 

[laatsch55]

The 94's are in the Sutton#3

 

[avionic]

Bad ones definitely have there own sound..or no sound.

 

[laatsch55]

Thanks Dave, very succinct.

 

[ksrigg]

I just ran across this copy in a guys ad on eBay for his Phase Linear 400. Here is what he said......"All 12 of the output transistors plus the 4 drivers (16 total) have been upgraded with new, matched date code 2ST5949's by ST Microelectronics. These are rated at 250 watt, 17 amp instead of the original 100 watt, 5 amp devices (which were pretty good 30 + years ago). New mica insulating washers and heat sink compound were properly installed. So now the output stage is significantly more robust (1500 watts vs 600 watts @ 25C dissipation capacity and 51 amps vs 15 amps current capacity, thus a much bigger SOA – safe operating area) per channel. What is the difference between these devices and the more commonly used ON Semiconductor MJ15024's you ask? These are super linear beta parts with virtually flat gains of over 100 typically to 7 or 8 amps versus betas of 15 to 20 for the ON Semiconductor parts. And the Ft is 25 MHz instead of 4 MHz"

Does this have any merit? Is it true? And does it really matter? I'm just trying to figure out what is what with this statement. As I haven't placed my order with Mouser yet, I may have to order some of these guys and have a REAL SUPER 400 !!!

 

[laatsch55]

There is a better chance of oscillation wth a 25mhz TO-3. The super linear bullshit, don't know about that. Order some and find out.

 

[ksrigg]

There is a better chance of oscillation wth a 25mhz TO-3. The super linear bullshit, don't know about that. Order some and find out.

I just thought it was fun reading, and didn't know if there was any thread of truth in it. That ios why I asked. I know you have the equipment to test this stuff, and the knowhow to do it. I really thought if there was any truth to it, that would be the transistor of choice. Figured there would be some streak of bullshit running through it. I'll check the price and may order enough to do a 400 with them. I know I won't be able to hear the difference however.

 

[laatsch55]

Now Sutton, you've already set yourself up for , in this case, NOT hearing a difference. Keep an open mind, it works that way.

 

[laatsch55]

Had a long chat with ED about that particular ad last night. Let's just say Ed is rather dubious about it also.

 

[Gepetto]

MJ21196 devices are much more thoroughly characterized than the ST device referenced here. The Ft for the 21196 is MINIMUM of 4Mhz vs. a TYPICAL of 25 MHz for the ST device. From an SOA perspective, the 21196 is capable of over 1 amp at 150Vce vs 0.2A for the ST device. My money is with ON Semi.

The 15024 is similarly rated except that the SOA is 0.5A at 150Vce.

Both devices are more rugged.

 

[orange]

I agree with Gepetto, whether I can understand it or not all the way and I agree that the characteristics of the output probably factor is the overall timbre of the output as well as distortion and transients that affect the sound quality.

As with tubes, the variations may be noticeable to the usual listener but if they meet specs it's no huge hoot usually.

There was a reason the designers used that combination of components but all modders know you can race a Chevette.