On 2014-09-20 5:12 PM, Jan Myren wrote:
> PS; do you have any specific experience with Revox recorders?

Hi, Jan,

I do have experience with the ReVox A77, but it was many years ago, 
though I still have one.

When I recorded over blank tape, the noise level came  up substantially. 
The Sony APR-5000 does not do that nearly as much.

Setting record levels higher can reduce noise, but trade that off for 
the risk of overload. You'll see that in the charts below as well.

If you are describing "rocks" in the recording (burbling, driving over a 
rocky road) that is due to bias nonlinearities which puts some DC offset 
into the recording. Bias nonlinearities are also a cause of the 
increased noise.

I have never tried recording on my Studer A80 machines, but the Studer 
A810, A807, and Sony APR-5000 record a lot quieter than the ReVox A77 
did. I assume that the B77 is quieter than the A77. It ended up being at 
least double the price with less discounting.

You do need to adjust the bias and EQ for lowest noise and distortion. 
That is an art. Study the curves from the tape manufacturer.

Download the data sheet for your tape and study it -- especially the 
chart on page 2. Then you will know what tradeoffs you are making as you 
adjust bias.

Unfortunately, the bias page at the same link does not cover LPR35.

By the way, I had Bias and LPR35 information from 2008 and it appears 
the same today as back then.

Good luck!

Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
Quality tape transfers -- even from hard-to-play tapes.