[topher]

 

[thomas]

(sorry for bringing this thread way off topic as usual...)

I'm just about to add an order from insight, so i'll add a few of those bjt's you mentioned...

sorry, i'm just starting to learn about discrete circuts, still trying to learn the different configurations/topoligies and all the calcualtions needed... Do you have any finished designs, or recommend any others that i could try? thanks a lot

 

[ppl]

The Discreet Component As Discribed By Jung. I would Add about 4 High Ft. Transistors in Parralell For The Output StageTo get about 2 amps into a Short.unless youare using High Impedance cans Then only about Half that is Required, To wire Up an Additional 3 To Jungs Exsisting Circuit is use a slightly more robust Driver Transistors. and use Individule Emmitter Resistors as Kevin Dose in His Amp, BTW I am sure that Kevins Output Stage can Be Changed to operate off an opamp rather than Discreet components. Ask Kevin Gillmore For This recomendations on That.

 

[ppl]

Tom. Since you are ordering From insight You may be Interested in my ULTAMATE AUSULT FOR PORTABLE HEADPHONE AMP.Thau employes 3 EL-2008CT's Per Channel to acoumplish what Kevin Did With His Supper Reg. However I had not considered His aproach But Mune dose the Thame thing as His provide a Stable Lowimpedance for the Output Stageboth Sinking as well as Sourcing Current. By operating these Three buffers in my strange but none the less Simply Sophisticated Arangement A separate virtual Ground Driver is not Required as what a more conventional supper regulator type supply. In addition no opamps are used because The Stand alone Buffer is alot faster than most any opamp is So Voltage reference is acomidated Between The Buffer Inputs on the Buffers used as the Drive for the output stage. If your interested can email sehematic monday. Proto Type sounds way Cool And quick. No large electrolytics are Now used in the output supply rails although i left provisions for 4 15K caps Total if need be But for Now i am using 2.2uF solens bypassed with 0.56uF/100 volt STK Teflon capacitors. so the room that used to be taken up by large slow electrolytics is now replaced with Film and Film/foil caps.

 

[thomas]

thanks...

yup, school's finally out, i plan on spending my whole summer working, and all the money i make is going to audio equipment... Finally have time to play around with the soldering iron....

Can you please e-mail me some schematics, ifor both the hp amp and the speaker amp? i'm not sure where to find Jung's designs

thanks!

btw, do you know if mylar caps are any good? I found a big bin at my local surplus store, and they look nice but dunno how well they actually work...

 

[aos]

ppl, those transistors specified for Jung's design are not weaklings at all. They read as POWER transistors in the datasheet. They can handle 15A continuous, 20A peak. and 83W dissipation at 25C, with 0.67W/C derating. They can surely handle puny 2A at 15V.

 

[skippy]

you can always try one of those pass labs zen amps that seem to be so popular. there are a lot of modifications out there if the original circuits are unsatisfying. i've been meaning to build one for a while, but could never find the time and resources for it yet.

 

[kevin gilmore]

I lug around a 12 volt 7 amp hour battery to power the
stax. 3 extra pounds. Big deal. For the quality of sound
it generates its worth it.

 

[ppl]

aos; Maby i failed to point out the real point of my post regarding Jungs transistor Selection. !st High Current Power transistors have Limited Ft and lots of Capacitence, So for Me I like A fast output Stage so I like To Parr. several Lower power transistors than use just one pair of Large Power types. And that why i like the Route Kevin went by using several TO-92's rather than what a conventional Circuit would do by just throwing a pair of High Power transistors in the Mix.

 

[aos]

I understand. These D44VH however are designed for "high-speed switching applications". They have fT = 50 MHz, Cob = 120pF, td=50ns,tr=250ns,ts=700ns,tf=90ns for pulse <300uS duty cycle <2%. I don't know if this is good enough for what you want though. But Jung probably selected these on purpose. I don't know who sells them. They are manufactured by Motorola. Newark, MCM, Mouser, Digikey - no one has them. Any suggestions...?

 

[aos]

Just found datasheet for 2SA1302. Silicon PNP Triple Diffused type. Complementary is 2SC3281. They are manufactured by Toshiba. Datasheet reads "Recommend for 100W High Fidelity Audio Frequency Amplifier Output Stage". No kidding - PC = 150W, IC = -15A, breakdown votage 200V. fT = 25MHz and Cob = 470pF so I would rather use Jung's D44VH for power supply, but for amplifier this baby rocks. Just as ppl said, hFE is basically flat as the IC changes. Btw transistors Kevin Gilmore specified for his amp also have flat hFE although they can go to much higher frequency - but they are low power.

ppl, where do you get all this good information? Do you work in the industry?

 

[topher]

Does anyone have experience using bypass caps on
the signal opamps when using opamp based voltage
regulators?

 

[ppl]

aos: Those D44's were origenaly made by GE then Ti and every one elce made Clones. I used to use these, Although Thay do not Have Good HFe Lineararity and the Compliment has hfe's that are way off so Matching and carfuff Biasing to get the Right ICq is a Must to use these. The 2sA amd 2sc types power types above are my Fav. for Loudspeakers. Motorola makes a version in the Same TO3-P package with a part #mjl-1302 & mjl-????. I made a 400 Watt/4Ohm 200Watt/8 Ohm Loudspeaker amp from these years ago whe Motorola offered these in A Metal TO-3. and i teel Ya That amp Rocks a Plenty.

 

[ppl]

Quote:

Originally posted by aos Just found datasheet for 2SA1302. Silicon PNP Triple Diffused type. Complementary is 2SC3281. They are manufactured by Toshiba. Datasheet reads "Recommend for 100W High Fidelity Audio Frequency Amplifier Output Stage". No kidding - PC = 150W, IC = -15A, breakdown votage 200V. fT = 25MHz and Cob = 470pF so I would rather use Jung's D44VH for power supply, but for amplifier this baby rocks. Just as ppl said, hFE is basically flat as the IC changes. Btw transistors Kevin Gilmore specified for his amp also have flat hFE although they can go to much higher frequency - but they are low power. ppl, where do you get all this good information? Do you work in the industry?

I used to But recent Health Problems have required my to take a break from that. But Nonetheless data acoumulated by me over the Years is still in My head. I have used about every Type Of Transistor, Tube and IC useable for Audio Amplifires and Other Related Stuff like Servo Motor Drivers. so i share this info with Members of this Site as well as any inquireing non Members.

 

[aos]

>so i share this info with Members of this Site as well as any >inquireing non Members.

I for one thank you for all the info you've dispensed so far. It's invaluable to have knowledgeable people around.

2SA1032 and its complement are also easy to find and cheap. What more could one ask for?