Headphone amp simulation

I grew up in a radio an TV repair shop... built many a "HiFi" amplifier, starting with 6V6... 6L6... finally KT88's, then went "solid state" when I went to Motorola after M.I.T.

(Also built several Dynaco kits.) ...Jim Thompson

That's what MicroSim Schematics does... better than Cadense, which is why they killed it off... can't have a cheap tool that's better than the over-priced Cadense.

Analog, or Digital? ...Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Surely, a hard sell to the kinds of clients shopping for IC designs.

Until (or if) they ever succeed in making the tiny kind reliable.

Tim

Indeed :-D

I have a 6DS4 (RCA Nuvistor) sitting here on my desk... and I've seen photos of experimental devices about the size of a surface mount capacitor.

For lots of HV applications I'm surprised that no one (*) has thought to put a transistor under the cathode of a tube... a lot more durable that a Power FET.

(*) Maybe someone has, somewhere? ...Jim Thompson

Well if you will use Labview to control your car...

was it signal conditioning for sensors and power control for actuators?

I can't imagine anything like that build in this century not controlled by an MCU.

-Lasse

MCU's can crunch numbers and do sequential things... but they don't do signal conditioning.

There was a quasi-MCU included in the chip core... Cadence provided that part, no less >:-} ...Jim Thompson

nd

by

that's kinda what I meant, no one would do it with out some kind of program mable controller so it would have to be front end for an MCU or have an MCU added to the chip

-Lasse

My customer bought the MCU core IP from Cadence and I added the signal conditioning around it, with glue logic (and MCU programming) provided by Mark Tse (quite a talent)... who thought I was around 50 years old... and was quite surprised when I told him I was coming up on 72 (at that time).

Now my next milestone is 3/4C :-D ...Jim Thompson

He was a programmer and probably meant it in hex (72 = 0x48) :-)

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Tek certainly did it a lot during their hybrid days, but if you mean co-packed, I can't imagine a 200C bulb temp would be so friendly, even if the chip is glass passivated (hey, just weld it onto the envelope, who cares right?).

I've also seen co-pack (or maybe they're actually monolithic?) BJT-MOSFET cascodes for moderate voltage switching applications, but I haven't thought of a place they'd be useful.

I used to tell people that an EL519 -- ignoring the heater power, or maybe not even, depending -- is still several times better than the best commercially available HV MOSFET. But, now that IXYS has some 2.5kV ~10A devices, that has also passed.

Tim

to put a transistor under the cathode of a tube... a lot more durable that a Power FET.

(*) Maybe someone has, somewhere?"

Shut the f*ck up if you want to live. those NSA guys don't play around. LOL

Problem is that the temperature at which thermionic emission get going is d estructive fro most transistors. for germanium it might be totally impossib le, for suilicon nby yhte time you derate it you will not have the power to feed a cathode driven amp, which would be the only purpose of suc a circui t.

Of course emitter turnoff has existed for some time now. when the load is h ighly inductive, they will take a transistor and turn it off on the emitter of the main transitor. This makes the biug transistor shieild the little e mitter transitor from the big bad voltage, but enhances whart REALLY happen s between the emitter and base of the big transistor. They actually used it in brownware for a short time, for wide screen CRT based projection TVs. t ha is until better transistors got ther (the 2SC5588 IIRC). then only the t races and silkscreening remain, and of course the one jumper. the drive cir cuit still sowed soigns of the scheme. I cna do a screen catpur if you have any interest in this, or if you can handle DWG files. Problem is it wasn't used in any units I worked on so I don't know how wlell it worked. In fact I wouldn't anyeay as I had no tinme for those unprofitable excursions much .

But yeah, a little shit ass transistor in the emitter circuit that could ha ndle the curtrent but not the voltage, wa sturned off as the big transistor was tirned off and the cpaacitance of the big transistor aided in its own turnoff.

Pretty novel little deal, and cheap. Applied to the cheapest pf the cheap t o save money on the drive circuit. As I said, better transistors came forth and the design was changed to eliminate this drive opitmization as soon as it was no longer needed.

Edit button. My Kingdom for an edit button.

"solid state" when I went to..." (snipped the part thar fuckd it all up...

I'm currently selling a pair of Chicago BO-15s. Were driven by 6550s, the G OOD versoin of the octal tubes. charging a hundred bucks. One guy in Chicag o wants them but I haev to shoip them. a local guy is offering half that. M aybe I kjust keep them. They are in a pair of monoblocks built by my Uncle. I still have the 6550s and the emossion tested fair to good a couple weeks ago. They hadn't been lit for ten years so they are probably better than t hat indicates, once you warm them up. and the getters are not all that gone . They are brown but not flaking off the glass.

The transformers are triple center tapped primary willianson type with four and eight secondary taps. the chassis' they are oin now are configured for 100 watts RMS (yeah I know) into four or eight ohms. The power transformer s are bigger thant they are. Which makes sense.

One guy offered fifty bucks. No way. hundred bucks her, or forget it. These things sounded great and might run, well one of them, if I had all the tub es. Well, maybe. Stole a few parts off.

You are just an IC away fom a new breed of amp.

But I ain't taking fifty bucks.

Can we switchmode these things and make them class E or F or someting ?