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Digital Amplifier Questions

I've been wondering the following:

1. Do digital amps benefit from being left on 24/7in the same way the ss amps do?

2. Is plugging a digital amp into a different outlet as your preamp as crucial compared to a ss amp?

3. Do digital amps have small transformers? If so, is distancing equipment from one another less important? (My peachtre Nova Pre/220 look best stacked)

4. When upgrading power cords on a digital amp, do you look for cords that do well with digital gear like your preamp and dac, or do you still go for a beefy cord?

I apologize ahead of time for my ignorance on the matter! Thanks!
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guidocorona
4,298 posts
 
Hi Tim, I recommend that you repeat test walking around with the radio as follows....

Amp 1 on, 2 and 3 off;
Amp 1 off, 2 on, 3 off;
Amp 1 and 2 off, 3 on;
Amp 1 and 2 on, 3 off;
Amp 1 on, 2 off, 3 on;
All three amps on.

G.
noble100's avatar
noble100
2,419 posts
 
Guido and Al,

Both good ideas; I'll get a battery powered portable radio (I've been needing to buy a new hair dryer, anyways) and set the dial to a low frequency on the AM band that lacks a strong station signal. Next I'll test with the various amps on/off according to the permutations Guido listed.

This amateur RF interference technician will report back on results soon.

Thanks,
Tim
guidocorona
4,298 posts
 
Tim, if you use a battery powered radio, and you find that one of the amps seems to leak, try sliding the radio along/around the amp case, and then along the power cord, the speaker wires, and the input ICs.... There is no telling from where the leak might originate... It might even come from a totally different device... Make no assumptions, as reasonable as they might seem.

G.
bombaywalla's avatar
bombaywalla
1,958 posts
 
03-31-15: Noble100

Thanks for the info Bombaywalla and Kijanki.

I tried the test again using the AM radio. I couldn't even find an AM station that was tunable. There was too much buzzing on the whole range. I'm thinking this is caused by RF leakage from my 3 class D amps, all located within a 5ftx 2ft area.

I plugged the radio into an outlet in my adjacent dining room (less than 20ft away) and the buzzing (hash?) went away and I was able to tune in a station in the low AM band.
why do you need to get a new AM radio?
Why can't you repeat the test (where you cannot even tune into any AM station due to the supposed RF interference from one of your class-D amps) with the existing AM radio & simply switch off one class-D amp at a time until you can tune into a AM station using Almarg's suggestion for the AM freq?
isn't this equally valid (as Guidocorona's suggestion of switching on the class-D amps one/2 at a time)?
thanks.
almarg's avatar
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almarg
9,670 posts
 
My feeling is that a portable battery powered AM radio would be preferable. Not only for the obvious convenience factor, but because it may make it possible to more accurately locate the source of any RFI, and to more accurately assess its relative amplitude as a function of distance. With an AC powered radio there may be ambiguity as to whether what is being picked up is being picked up by the built-in antenna, or by the long power cord acting as an antenna, or that is perhaps being routed into the radio via the power wiring itself.

Just my opinion. Best regards,
-- Al
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