This is not just another gainclone

[Philo]

MatttCattt,
Can I ask why youare limiting your current? I have both 541 and 549 prototypes set up now and and just shorted the leg. The amps sound great and have had no problems!

[Peter Daniel]

Hi Philo,

I'm currently building OPA549 amp. The rails can't go higher than +/-30V and pins 6 (ref) and 8 (I lim) connect to ground, right? Are you using inverted, minimized config.? Any other areas worth consideration?

[Mad_K]

Originally posted by Philo
MatttCattt,
Can I ask why youare limiting your current? I have both 541 and 549 prototypes set up now and and just shorted the leg. The amps sound great and have had no problems!

The 549 is current limited at 10A when you short I_lim.
The 541 in not limited at all when you do this. You won't have a problem with this approach until the you overdrive the amp or short the outputs. If the output of the 541 is shorted, you will have your rail voltage over you speakers If you draw more current than adviced, the chip may go up in smoke, and your speakers might be

[pinkmouse]

Originally posted by Peter Daniel
Hi Philo,

I'm currently building OPA549 amp. The rails can't go higher than +/-30V and pins 6 (ref) and 8 (I lim) connect to ground, right? Are you using inverted, minimized config.? Any other areas worth consideration?

Whilst we wait for Philo's response, I thought I'd share my experiences.

I connected ref and lim to each other, then to ground, left the status pin floating, and used the minimised inverted config with the addition of adding back the 1uf cap across the + & - pins.

I used (for testing only) a 75VA 18-0-18 AC traffo, as my bigger 300VA that I use for my LM3875 and OPA548 at 24-0-24 AC seemed to cause the inbuilt protection to cut in, even though it gave only 28.5V regulated

(edit) I meant to say 22-0-22, not 24-0-24

[Peter Daniel]

That's what I plan to do. As I recall you mentioned it sounds better than LM based amp. Did you try TDA7294?

[pinkmouse]

Originally posted by Peter Daniel
Did you try TDA7294?

Not yet, no money for hobbies at the mo...

I think I might have also have changed the value of the feedback resistor, but I can't remember why, and what to, and I'm away from home at the moment for a few days so I can't check!

[Elkaid]

from Peter Daniel As I recall you mentioned it sounds better than LM based amp. Did you try TDA7294?

Now that I've finished my LM3875 based GainClone, I'll go back on my TDA7294 based amp so expect news from me soon.

Just to make a short story, I had some problems with TDA7294 concerning oscillation and mysterious explosions (I finally found out that it was due to overvoltage hmmm hmmm).

The TDA7294 has very impressive dynamics and detailed sound (not to mention high output power. If more power is needed, there's the TDA7293 which accepts higher voltage rails and can be bridged using several 7293 ICs)

[Bricolo]

Originally posted by Peter Daniel
That's what I plan to do. As I recall you mentioned it sounds better than LM based amp. Did you try TDA7294?

AFAIK, this chip is possessed by evil

[Bricolo]

Originally posted by Elkaid



Just to make a short story, I had some problems with TDA7294 concerning oscillation

did you manage to solve them?

[Bricolo]

My local resealer hadn't MKP caps, he gave me 0.1uF MKH istead
are they also good? I don't know what does those caps name mean