I replaced the sovtek tubes in my 737 with a NOS set of RFT ECC88's.
There was no change in gain, and I could not detect any extra noise
compaired to recordings made with both sets of tubes. I have had them
in the 737 for about a year now with no problems. I didn't do a full
scientific test of all functions, but I did do pre and pre/comp
comparisons with prerecordrd tracks. The RFT's brought a slightly
different character to the sound of a Neumann TLM 193 and acoustic
guitar. They seemed to make the mids a little more pronounced with a
warmer top in the dog ear zone. The compressor results were similar
to the original tubes, but I didn't do any comprihensive comp test. I
thought it was a good combo with the TLM 193. I liked it and left
them in. The truth was the difference was very small to my ears, but
I have played a few thousand gigs. Just wanted to see if anyone
else out there has tried experimenting with the tubes in the 737.

David Brouillette

www.basswhore.com