PPA amp and er-4p noise

[Fangmasterflex]

When i use my er-4p's in conjunction with my PPA, at low volumes the sound is clear. However when I turn it up to what i think is a comfortable listening level, it will play clear sound for about 1-2 seconds, then immediately switch over to pure noise. The amp works wonderfully with my 650's and even low impedance el cheapo headphones, and wont produce such noise even at max volumes. The er-4p's also sound normal when in another source like my mp3 player. Any idea on what could be causing the noise? Do you think a er-4p->4s converter would help?

 

[tangent]

Quote:

it will play clear sound for about 1-2 seconds, then immediately switch over to pure noise.

It could be oscillating. What's the PPA's configuration?

 

[Fangmasterflex]

Its currently running 637 opamps, larocco diamond buffer, STEPS psu, and with a gain of 11

 

[Fangmasterflex]

Just replaced the 637's with a set of spare 8610's and fixed the problem

 

[Sovkiller]

The 637 is a cranky little person opamp, to make it work properly in the PPA with the diamond buffers it needs some work, and even that way, it will sometimes get out of hand. If you can, you could try the AD8065...

 

[tangent]

Quote:

637 opamps, larocco diamond buffer

This is known to be a cranky configuration, at best. Have you contacted LaRocco, to see if you're doing all of the little mods they have for higher stability?

 

[Fangmasterflex]

not as of yet, but i'll be sure to do that

 

[binary_digit]

Hey Fangmasterflex,

couple questions for you...

1. Did you build the amp yourself?

2. Did you install the Buffer Yourself?

3. Is it Dynamic, or standard bias?

 

[Fangmasterflex]

The amp was built by me, buffers installed by me, and has a standard bias