TOPIC:

Hi,
I've received and connect the DDRC-22A to my system, and realized immediately that it has a very high noise floor.

I am using a pair of active 110db sensitivity horn speakers so it is clearly audible from the listening position. It sounds like Saaa...... at the background with a louder 3Khz spike which I think it comes from the switching power supply.

I concluded the noise from the unit/power supply because:
1) once I disconnect the power from DDRC-22A (it is fully connected), the noise is gone.
2) The noise is there (with same loudness) when there is no input cable connected to it when it is on (only output connect to rest of the system).
3) Noise is gone when I completed disconnect the unit from system.

I am connecting the unit between Accuphase df-35 active XO and preamp via XLR connection both set at 2V max (So I believe this is not pairing issue).
I have ground connect only via preamp to eliminate ground loop issue plus using a audio grade isolation transformer on the unit does not help with the noise.

Although, I have the DIGI-FP board order along with the unit. I cannot use it to connect via digital I/O as I have only vinyl as source.

I am consider getting a linear PS but I guess it can only remove the 3khz spike. Any recommendation to combating noise is much appreciate. Thank you very much.

I'd be inclined to try putting the DDRC-22A before the preamp. If you have more than one analog source, that is obviously not a good long-term solution but it might be informative.

Thank you for the suggestion John,
I have considered this, however I have more than one phono, plus my phonos have no balance out.

Do you know mods that can reduce the noise?

Well, one "mod" would be to put use an attenuator to reduce your excess gain. I suggested a simple way that you can try it out...

I had tried. It takes at least -10db to hide the noise completely. It really kills the dynamic of the system. Not a good solution sadly.
I had also try with a linear ps. Again, it didn't help to lower any noise at all.

Any idea what causes the noise in the analog stage?

Um... did you try what I suggested?

Yes I tried yesterday, It takes 10db attenuation to hide the noise which kills all the dynamics.
There isn't any excess gain in my system.

Looks like I have to mod the analog I/O stage.

Might be more straightforward to use the DIGI-FP into the Accuphase and add an external A/D convertor? (I assume that is why you bought the DIGI-FP?)

It is indeed easier to just buy a 96k adc.
However, I have been trying to use less equipment unless it offer sonic improvement. I have got enough audio equipment already plus i like moding audio equipment.
I brought the DIGI-FP was because I thought I can use the AN-FP as ananlog input and DIGI-FP as digital out.
Now since the input buffer might be noisy. Only solution is to get external adc or moding the analog l/o.
I really like to keep DDRC-22 as it has offer improvement on sonic imaging. I have much better eq result with it than the lot more expensive Accuphase Dg28, Dg38 and Dg-48 except they are a lot more silent.
Thanks.

I can relate to your circumstances, I have Avantgarde Duo Omegas.
It can be very challenging to keep system noise below the audible limit.

I am using the DDRC-22D and can assure you that zero noise is introduced into my system.
Unfortunately the DDRC-22D has digital in and out only.

I discussed this at length with miniDSP Team before making my purchase.

As pointed out, attenuation may help to lower the noise floor.
I would not apply the attenuation with the DDRC utilities feature.
I would recommend trying the Rothwell Balanced -10dB attenuators either on the input or the output and see where they work best.

Sorry to reply (or dig up) such an old post.

I have been attempting to build an adc so I can use the Digi board. The adc will be based on pcm4222evm and all parts has been gathered.

However, I wasn't able to complete the project before my wife gave birth to a twins. So I guess there will be a delay.