REDDI noise specs

[TC5]

Any REDDI users can comment on the self noise level of the REDDI compared to say an Avalon U5 or other equivalent Di, used for bass (Fender Jazz for instance) or guitar? The A designs specs don't include signal to noise ratio info. I'm not sure how the interpret the -126db EIN spec figure. Thanks for any input.

[peeder]

The REDDI doesn't have a particularly high noise floor, provided the tube is healthy, but the transformer in it will pick up a fair amount of hum from its own internal power supply.

Of the two I tested, the original version (lacking a thru jack) had less hum. Both had similar noise levels.

The EIN spec is to me fairly worthless, it's something they put on mic pres etc. but you never get that much dynamic range in practice.

[rcm]

FYI, Peeder seems to be the only one that has had a problem with hum and the REDDI. (that I am aware of) Not to say what he is talking about is not real in his experience, but there are other threads on this and it seems no one else is having this problem.

[peeder]

And FYI, I'm the only person on GS that I've seen properly evaluate a noise floor on anything...

(Who knows why...it's dead simple...but people can't seem to get themselves to do it... )

[TC5]

Right I read the thread about the hum. I'm thinking more about normal noise floor level.

[jmarkham]

Originally Posted by peeder

And FYI, I'm the only person on GS that I've seen properly evaluate a noise floor on anything...

(Who knows why...it's dead simple...but people can't seem to get themselves to do it... )

What is your measuring device?

jeff

[Tony Shepperd]

Once again, the hum only Peeder can hear.

[peeder]

Originally Posted by jmarkham

What is your measuring device?

jeff

Gain stage using a test tone, establishing the clip point. Then bring the signal into digital via a very high dynamic range ADC. Gain stage that as necessary, record, then mute the test tone to record the noise floor. Apply 70db+ of clean digital gain to hear the quality of the noise floor, view it on an RTA, and evaluate its RMS level.

Doing comparisons of competing products this way is often quite enlightening. And be sure to include straight wire as a baseline comparison (of the converters etc.).

I would never dream of setting up a racking arrangement without doing this, to ensure that pieces of equipment weren't interfering with each other. (You will develop a new respect for external power supplies when you adopt this discipline.) You have to test various things if you get hum, for instance, ground loops, chassis orientation, chassis ground, cabling, mains ground, etc. Whines and the like may be related to converter sync. There's all sorts of crap down there you might be ignoring.

There is no need for fancy AudioPrecision rigs just to evaluate a noise floor...

[peeder]

Originally Posted by Tony Shepperd

Once again, the hum only Peeder can hear.

And once again, three out of the four LA guys (where's pan60?) who will never let a single criticism of an A-Designs product be posted without screeching at it.