AudioCircle

Industry Circles => Bryston Limited => Topic started by: wireworld on 10 Apr 2004, 09:10 pm

Title: BP25 possible problem. Help appreciated
Post by: wireworld on 10 Apr 2004, 09:10 pm

I have a BP 25 which is about 18 months old (new type power supply connected to a 4bst) and have recently noticed a bleeding of signal when inputs are playing but not selected.  This is only noticeable at high volume levels but is louder at the selector positions adjacent to the connected ones.  

I have tried various interconnects (shielded and not) but it makes no difference.  Is this a known issue and/or are there any suggestions as to the cause/solution?

Thanks in anticipation of your assistance.

Title: BP25 possible problem. Help appreciated
Post by: jethro on 20 Apr 2004, 09:31 pm

I've never used more than one input with my BP-25 so I can't be of much help.
If you haven't already tried it, perhaps you could try two of your source components, and associated cables,with another pre-amp and see what happens ? This might help narrow down where the problem lies.

Title: BP25 possible problem. Help appreciated
Post by: James Tanner on 20 Apr 2004, 10:09 pm

Hi Wireworld,

Sorry I did not notice this earlier.
You will get some 'bleedthrough' from one input to an "adjacent" input if the volume control on the BP25 is very high and the source component has a very high output. The BP25 is capable of 30 volts out and so adjacent signal traces on the circuit board may pick up the signal. As you move further away from each input the effect is reduced.
If there are 2 signal sources you like to have on at the same time just move one of the sources inputs further down the selector switch.

james

Title: BP25 possible problem. Help appreciated
Post by: wireworld on 22 Apr 2004, 05:18 pm

Thanks for the reply, that sound exactly the effect I have.  I often leave my tuner on whilst listening to the CD and the marked positions just happen to be ajacent to each other on the selector.  I'll try and seperate them as much a possible even though it may be difficult for my sensibilities to have the tuner selected through the disc input :D

once again thanks

Title: BP25 possible problem. Help appreciated
Post by: James Tanner on 23 Apr 2004, 01:59 pm

Hi Wirewold,

This is the response I received from engineering on your crosstalk question. It does a much better job at explaining it. NOTE: crosstalk is not an issue with terminated inputs.

james

This specification is only meaningful as pertains to inputs which actually have sources connected to them. One never 'listens' to unused inputs.

When an adjacent input is TERMINATED with the average source impedance (as from CD players, tuners, etc.), of roughly 100 Ohms, the crosstalk falls to levels below the noise, in the area of below -120dB up to 1kHz, and below -105dB up to at least 10KHz. Thus, the crosstalk to an actual signal-producing source is below the noise, and thus inaudible.