[00940]

this is what you're after : http://headwize2.powerpill.org/proje...awliw1_prj.htm

btw, the BUF03 is discontinued but you can replace it by a BUF04.

If you implement a gain switch, it could also a pretty good preamp. The buffer circuitry is cheap and easy, but don't be fooled, you need an outstanding PS to get it running perfectly.

 

[Jupiter]

Yes, looks like another project I have to try. Thanks

 

[peranders]

Quote:

Originally posted by rickcr42 good luck finding the LH0033/66 parts . They have been obsolete for some time.

I have 3 LH0033 for sale..... in gold very nice.

 

[Jupiter]

Quote:

Originally posted by 00940 btw, the BUF03 is discontinued but you can replace it by a BUF04.

Anyone know which of these buffers sound better, in case I find a few BUF03?

 

[Steve Eddy]

Quote:

Originally posted by Jupiter Anyone know which of these buffers sound better, in case I find a few BUF03?

You're the only one who can provide any meaningful answer to that question. Give 'em both a try and decide for yourself.

se

 

[Jupiter]

You're right, but the BUF03 will probably be $20 each.

That's a waste of many if it sounds the same as BUF04 ($7.50 each).

 

[Steve Eddy]

Quote:

Originally posted by Jupiter You're right, but the BUF03 will probably be $20 each. That's a waste of many if it sounds the same as BUF04 ($7.50 each).

Sure. But of course you won't really know until you've tried 'em. I think Joseph Heller wrote a novel about that.

se

 

[00940]

don't know jupiter, but there was a post somewhere on diyaudio saying that the Buf03 had something magic the buf04 didn't really have anymore

 

[puppyslugg]

Jupitor:

If you're willing to give the buf03's a shot, I have a few. PM.

 

[Joe Lau]

I had design a very simple hybird buffer. It is very simple. A 6BQ5 Cathode follower direct coupling to a IRFP150 and capacitor coupling to 32 Ohm Headphone. It is simple , low cost and sound good for Low impedance Cans. It can drive high impedance Cans if you connect it to pre-amps output.

 

[zzz]

buf04 has been obsoleted by analog.

Quote:

Originally posted by Joe Lau I had design a very simple hybird buffer. It is very simple. A 6BQ5 Cathode follower direct coupling to a IRFP150 and capacitor coupling to 32 Ohm Headphone. It is simple , low cost and sound good for Low impedance Cans. It can drive high impedance Cans if you connect it to pre-amps output.

interesting choice of components. even if you manage to rig 6bq5 to run at its peak current of 65ma at all times with a ccs or something, the maximum theoretically achievable slew rate of that circuit is going to be under 23v/us (3kv/us for the discontinued buf04 and 1.3kv/us for the intersil ha-5002). I'd expect imd of that hybrid buffer to be quite up there.

 

[Jupiter]

Quote:

Originally posted by Joe Lau I had design a very simple hybird buffer. It is very simple. A 6BQ5 Cathode follower direct coupling to a IRFP150 and capacitor coupling to 32 Ohm Headphone. It is simple , low cost and sound good for Low impedance Cans. It can drive high impedance Cans if you connect it to pre-amps output.

Do you have a schematic or a link? (I'm sure it's simple, but I don't know how to build the circuit you're describing.)


Quote:

Originally posted by zzz buf04 has been obsoleted by analog.

Thanks for tip. Luckily, Newark has a few of these in stock.

 

[rickcr42]

Quote:

interesting choice of components. even if you manage to rig 6bq5 to run at its peak current of 65ma at all times with a ccs or something, the maximum theoretically achievable slew rate of that circuit is going to be under 23v/us (3kv/us for the discontinued buf04 and 1.3kv/us for the intersil ha-5002). I'd expect imd of that hybrid buffer to be quite up there.

slew rate is not a problem as long as the preceeding stage does not exeed the final stage,that is where you can run into problems.

fast in slow out is a disaster

The final stage must have the most speed

and jeez guys , how much slew rate do you think is really needed anyway ?

A kazillion volts per microsecond sounds good but is it needed ?

No.

how many tube amps are slow on paper but yet sound exeedingly fast in real life ?

and let us also remember how important layout becomes at these extreme speeds - almost fast enough to require an FCC liscence

 

[zzz]

Quote:

Originally posted by rickcr42 slew rate is not a problem as long as the preceeding stage does not exeed the final stage,that is where you can run into problems. fast in slow out is a disaster The final stage must have the most speed and jeez guys , how much slew rate do you think is really needed anyway ? A kazillion volts per microsecond sounds good but is it needed ? No. how many tube amps are slow on paper but yet sound exeedingly fast in real life ?

well, there's slow and there's VERY slow. in real conditions you won't run el84 at higher at 15-20ma anyway, and probably won't use anything but a cathode resistor to bias it. that would give the circuit non-symmetrical slew rate on the scale of 1v/us or something like that (typical input capacitance of that mosfet is 2.8nf). and yeah, it certainly isn't all about speed, it was just the easiest thing to pick on. the hexfet in question is a 41A beast, you'll need to bias it at a couple of amps to get acceptable linearity (just look at its transfer curves). then the output cap.

I'm not bashing the approach (though I'm not in favor of slapping parts together in a `just because you can` fashion). I really only meant what I said -- curious choice of components.
Quote:

Originally posted by rickcr42 and let us also remember how important layout becomes at these extreme speeds - almost fast enough to require an FCC liscence

heh, only if your amp oscillates. always obey the datasheets

.

Quote:

Originally posted by Jupiter Do you have a schematic or a link? (I'm sure it's simple, but I don't know how to build the circuit you're describing.)

probably something like that. bias points were pulled out of the hat.

 

[rickcr42]

Quote:

I'm not bashing the approach (though I'm not in favor of slapping parts together in a `just because you can` fashion). I really only meant what I said -- curious choice of components.

I hear that !

back when i was going hybrid on my szekeres amp I tried to just slap a tube gain stage to the front end and it was not as easy as it would seem .

my best results came with an optimized 5687 srpp satge at 15 db gain and running seriously hot !

sounded pretty damn sweet though