Noisy eTap2hw

Moderators: George Geddes, David Martin, dave robinson, Iain Purdon, ecca

Re: Noisy eTap2hw

Postby Amanda » Mon Nov 26, 2012 12:24 pm

Those switched mode power supplies are not so good unless they are designed
with the correct EMC filtering, you should hear the noise they create in the
Rf spectrum on amateur radio equipment.

Glad to hear that using a battery cleared the buzzing..

Amanda
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Re: Noisy eTap2hw

Postby GuitarPhil » Mon Nov 26, 2012 2:10 pm

Dick,

There are another couple of the eTaps being built by other Club members so, as you say, it will be interesting to compare them side by side - then I'll know if it's just me being hyper fussy :o

Cheers and will post the results as soon as the others finish their boxes.
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Re: Noisy eTap2hw

Postby Amanda » Mon Nov 26, 2012 3:53 pm

Hi Phil,

I should have mine working by the end of the week so I'll replicate the tests and record the results..
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Re: Noisy eTap2hw

Postby GuitarPhil » Mon Nov 26, 2012 11:44 pm

Thanks Amanda, will be interesting to hear your results.
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Re: Noisy eTap2hw

Postby ecca » Wed Nov 28, 2012 5:34 pm

I've built 18 of these things and 2 were reported as noisy, one was a setting level thing and the other was a silent as the grave back in my workshop.
There's no way they're inherently noisy.
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Re: Noisy eTap2hw

Postby RogerCook » Wed Nov 28, 2012 7:04 pm

I've just finished building 3 units. Having had a good listen there is some hiss evident and "jumpering" the in and out amps does show this comes from the preamp stage. However I wouldn't say it's excessive or intrusive - I had to listen carefully to detect it - and I guess it's what I would expect from an effects unit. I have commercial pedals that hiss more. In a performance environment I doubt it would be noticed.

Sorry I can't record the result as my computer with decent(ish) soundcard has stopped working (and is hardly worth fixing it's so old) and my laptop has only a mic in which is very noisy anyway

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Re: Noisy eTap2hw

Postby David Martin » Wed Nov 28, 2012 7:14 pm

Solved my problem...

Discovered that my guitar pickups were picking up the echo unit's processing radiations - have had that problem with computers too... Sitting too close so I could fiddle. Two feet away, or with humbucking configuration, no noise at all...

Chump... :oops:
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Re: Noisy eTap2hw

Postby GuitarPhil » Thu Nov 29, 2012 6:10 pm

Sorry, I managed to double post :oops:
Last edited by GuitarPhil on Thu Nov 29, 2012 6:13 pm, edited 1 time in total.
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Re: Noisy eTap2hw

Postby GuitarPhil » Thu Nov 29, 2012 6:11 pm

Op-amp differences: NE5532P and NE5532AP.

The part specified by Piet in his BOM http://www.echotapper.nl/wp/?p=151 is the AP version but in my kit from Newtone I was supplied with the P versions. The P type is a little cheaper but, other than that, the difference, according the Texas Instruments data sheet, is that the 'A' variants have guaranteed Maximum Input noise voltage limits.

The typical value for both types is 5uV at 1kHz but the A type is guaranteed not to exceed 6uV. There is no max figure quoted for the other variant.

Could I have been unlucky and got a noisy pair of NE5532P's ...?

I also found this recent link on the TI forum where someone is complaining about noise issues even with the NE5532AP.

http://e2e.ti.com/support/amplifiers/precision_amplifiers/f/14/t/344.aspx

I will try swapping my NE5532's with a pair from my mates kit and see if it makes any difference though there could be a problem with this batch.

This is still an itch I can't quite reach! :ugeek:
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Re: Noisy eTap2hw

Postby Twang46 » Thu Nov 29, 2012 6:46 pm

Just checked my Etap Phil & the op/amps are the "P" variety. Also the kit that arrived yesterday has the same.

Mine is one of the pre production models so it may well be that Piet allowed the use of the "P" models because he (like me) didn't think that noise would be a factor using these well proven devices.

I don't think these are your problem (but you never know ;) )

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