Toft ATB bleed

[klangtone]

Toft ATB users, I have a question/request for you.

I recently got a Toft ATB32 (upgraded from a 16). It's brand new (v3.0). One of my first tests of the board all wired up was to send a tone to all 32 channels just to make sure signal was passing. Well, what I found surprised me. Even with all faders down and/or muted, if I turn up the master fader and crank the main speaker volume knob, I hear some bleed of the tones on my speakers. I swapped out the cabling for 8 of the channels with a known good cable I've used before and even just with those 8 channels going, the bleed was still there.

I got in touch with Toft and actually visited their office in CA today (luckily I live within driving distance). They brought up another console for me at their office and we repeated my test. Sure enough, with enough gain on the monitors, some bleed of the tones was audible. The tech basically said, I guess that's normal! It's not a test they ever do, apparently.

I'd like to find out from other Toft owners if it is indeed normal. So, if you have a chance to do a test like this, please post back on your findings.

For the most part, I think I can live with the bleed. If you need to totally mute a channel you can always do it in the DAW. But if mixing off tape, it could be an issue. Luckily, I tend not to do that, even if I record to tape. But anyhow... it just doesn't seem right. Such a basic function should perform better on an otherwise excellent mixer. I'll have to go back and check my old ATB16 to see if it did the same thing. I don't recall having such an issue, but I also don't recall ever looking for it.

Thanks,

Roy

[Snarl 12/8]

Don't some circuits behave unlinearly at the extremes of their operation? It sounds like you're maxing the main fader and the control room knob. Are you sure that the sound of the muted tracks exceeds the noise floor of the mixer in the more normal operating range of those amp stages?

[Jim Williams]

I ran the Toft through the Audio Precision analyzer I use here a few years back. I found a lot of leakage and crosstalk. It measured IIRC -55 db or so, not so good. Compare to my Soundcraft Delta that does -90 db at 10k hz, the most difficult frequency to control.

Those Toft mods I posted several years ago fix that problem. Crosstalk was improved to -74 db, not too bad. A 20 db improvement is something you can easily hear.

AFAIK, Toft never used those fixes, they still make them the same way as the first versions. THD was also poor at .4% at +10 dbu. That was reduced to .003% at +27 dbu outputs. That is why you can never mix past +3 on the meters, it all falls apart.

[klangtone]

Thanks for the replies.

I am inputting +4dBu on each channel and have the master fader at 0.
The tone bleed is noticeable with the main speaker volume knob at levels less than max too. So I don't think I'm necessarily pushing things into their un-linear extremes.

Jim, I sent you an e-mail at the address on your web page. Let's talk more off line about your mods and how they might help.

I just checked my old ATB16 and it has the same issue. So this is definitely nothing new or out of the ordinary for the Toft brand.


Roy