cross talk in tube mixer

i have extra filtering stages for L and R channels on B+,
and RMA tells me my stereo crosstalk is 96db.
which is pretty good. listening test sounded good vs bypassed...

would i benefit for extra stereo crosstalk figure by doing same extra filtering on DC heaters for L and R channels also.
(i would try but out of caps)

Just try it. Put signal in 1 channel, listen to the other. 96dB is A LOT!!!
Considering the stereo separation on a vinyl record is about 20-30 dB, you dont have a problem.
Try not to create problems where there are none.

If you are using RMA with a 16 bit sound card the 96dB is the limit of is measurement capability. Your cross-talk might be less but RMA won't be able to measure it. As other have said, 96dB is a very good result. At Neve back in the 70s re target spec was 90dB.

Cheers

Ian

ruffrecords said:

...At Neve back in the 70s re target spec was 90dB.

Click to expand...

Which is very high, if I remember right there was no media to record to which offered such good crosstalk numbers before everything went digital.

Michael

i was measuring 24bit... 
my AD/DA loopback measures 114db something....

kambo said:

i was measuring 24bit... 
my AD/DA loopback measures 114db something....

Click to expand...

OK, so your reading is accurate. Still plenty good enough.

Cheers

Ian

finally hooked up my regulated 6.3VDC heaters, in parallel,
my stereo crosstalk is 79db now  ??? :

i tried filtered heater supply (parallel) ,  crosstalk is still 79db... something must be with the serial connection! any idea ?

Again, you are obsessing about something that is fine. If your crosstalk was less than 20 I would be looking to fix it.  You are well ahead of that.

radardoug said:

Again, you are obsessing about something that is fine. If your crosstalk was less than 20 I would be looking to fix it.  You are well ahead of that.

Click to expand...

haha  i guess i am obsesed with noise floor and all other parameters 
anyway, managed to bring it back to 95 

Michael Tibes said:

Which is very high, if I remember right there was no media to record to which offered such good crosstalk numbers before everything went digital.

Michael

Click to expand...

Quite right. Most multitrack tape machines could manage only 40dB.

Cheers

Ian

i forgot the exact number i think it was 64db crosstalk on my first attempt, i could totally hear the difference.
there is a reason why some companies was aiming for 90db crosstalk!
since i am using digital, i rather have the crosstalk as low as possible!

so, where i am at is,  crosstalk figures are changing with how wires are placed... even tho i am using shielded
wires, its still messing with the crosstalk figures.
i am using mogami 2330, may be i should use something better ?

all sorted...
now crosstalk is  better than 91.8db regardless of wiring directions...
and my 6 matched new production tung-sol  6SN7 s just arrived 30 min ago... warming them up 

You can hear the difference between 60 and 90 dB crosstalk? When you are listening to both channels on a normal stereo?
You need to get down to the Guinness Book of Records.

unless RMAA was measuring wrong,
when i was doing listening tests i was able to... which way to Guinness  8)

Listening to both channels, signal in one, crosstalk in the other? I can understand it if you were only listening to the crosstalk, but with both at once it would imply that your hearing was phenomenal.