Noisy eTap2hw

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Noisy eTap2hw

Postby GuitarPhil » Wed Nov 21, 2012 10:37 pm

Just built my first eTap2hw and, whilst the echoes sound great, I'm a little concerned about the amount of hiss I am hearing through the amp. I have just connected the guitar to the eTap2hw and then straight to the input of my Laney VC15-110 (a 15W valve amp). I can roll off the treble on the amp and turn off the bright switch which helps a bit but then the tone isn't what I like. I also tried the same arrangement with my Marshall AVT50 and the hiss is quite audible with it too.

When the eTap2hw is connected to the computer through my Focusrite interface the hiss doesn't seem as bad. I recorded some 'silence' from the eTap2hw and from my existing setup for a comparison and the eTap2hw is as quiet if not quieter so it looks like it's an interaction with it and the amp inputs, maybe :?

I had originally made the audio connections inside the aluminium diecast enclosure using plain wire but on ecca's advice I re-wired using screened cable but this made no difference :cry:

Perhaps I am being overly critical but I think I read someone's comment on here how quiet their unit is :?

If anyone has come across a similar problem and found a solution I'd really appreciate some help.

Cheers.
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Re: Noisy eTap2hw

Postby Echotapper » Thu Nov 22, 2012 8:38 am

Testing eTap2hw

The eTap2hw unit is build as a two-channel unit with identical components on both channels making fault finding easier.

The first check is to assure noise is not enter through input:

- Short your guitar input and notice differences

The second check is to only check the motherboard:

-Remove power and carefully remove the daughterboard ( static charge risk so place on metal or aluminum foil)

- Inserted jumpers between 1 and 13 and 2 and 14. When that connection is made both your dry signal path and your wet signal path are connected and amplified like a preamp. Notice any differences

-If difference detected swap jumper 1 and 13 and retest to find what channel is different. If difference between channels disconnect the wire from the output on your motherboard and insert it in the other output pin that's idle in the final configuration. Notice any differences.

It is assumed that a single earth connection is made through the motherboard to the case or case-input jack-earth connection at input motherboard. If not sure also test with a quick test with a wire between aforementioned points.

If possible make some pictures of the board on both sides and send to me so I can do a first visual check.

Piet
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Re: Noisy eTap2hw

Postby GuitarPhil » Thu Nov 22, 2012 1:06 pm

Piet, many thanks for you detailed suggestions. I will try this later and let you know the results.

I already tried shorting the guitar input and this makes no difference. I will do the other checks as soon as I can.

Thanks for all the hard work you put into bringing us this wonderful project Piet.

Phil.
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Re: Noisy eTap2hw

Postby GuitarPhil » Thu Nov 22, 2012 6:29 pm

OK Piet, I just need to clarify something with you so you know how I have things wired up.

I have my input jack 'hot' connected to the LEVEL pot via 33k resistor

Wiper (terminal 2) of LEVEL Pot is connected via screened lead to INPL and INPR pins on the motherboard. Screen of this lead goes to GND2 on motherboard.

The input jack ground connected to GND1 and to the LEVEL pot terminal 1.

The WET/DRY output jack 'hot' is connected to OUTL.

The WET output jack 'hot' is connected to OUTR.

These output jacks are grounded through the metal case

If you spot something wrong here please let me know. I will try to post photos later.

Thanks a million!

Phil.
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Re: Noisy eTap2hw

Postby RogerCook » Thu Nov 22, 2012 7:30 pm

Phil

What you describe sounds right to me though I don't have anything connected to the wet only output on the board. The test Piet suggests of connecting the "in" and "outs" on the 16way header should enable you to see if it's something in the motherboard that is causing the noise. You'll need to connect your amp to the right output on the motherboard when you check the right channel, though as the right output isn't actually used in the wet/dry mix output this shouldn't be contibuting to any noise. You can also cross connect the left pre effect to the right post effect circuit aand vice versa ie pin 1 to 14 and pin 2 to 13

One other thought - could the noise be coming from the power supply? It might be worth trying an additional capacitor (1000uf or so) across the supply

Roger
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Re: Noisy eTap2hw

Postby GuitarPhil » Fri Nov 23, 2012 12:17 am

Roger, tried the capacitor thing - no joy I'm afraid.

Before I go any further with this 'noise hunt' I thought I'd better post a sample so everyone can hear it and, if necessary, tell me I'm being too fussy!

This is a link to Peacepipe, recorded straight from the eTap2hw to the computer. No amp, no amp sim plugins or anything like that. At the end I let the recording run on for 5-6 seconds so you can hear the noise I have been going on about - maybe it's not so bad but it seems worse when the unit is plugged into my amp.

http://www.4shared.com/mp3/MJDF8qMI/PeacePipe_eTap2hw.html

Cheers everyone :)
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Re: Noisy eTap2hw

Postby ecca » Fri Nov 23, 2012 7:22 am

Phil it's hard to say just how noisy it is sitting here miles away.
What happens when you de-plug the lead from the input of it ?
Is it noisier with the lead in or out ?
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Re: Noisy eTap2hw

Postby RogerCook » Fri Nov 23, 2012 8:52 am

Phil, I agree with Ecca - hard to tell from the recording. Maybe my higher frequency hearing is getting worse than I imagined (!) but what I do hear (through headphones) is some noise that I would have thought was in the 150 to 200Hz range rather than hiss. I have a few units in construction that I should get finished early next week so I'll check on those and report back.

By the way, what PSU are you using?

Roger
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Re: Noisy eTap2hw

Postby Twang46 » Fri Nov 23, 2012 9:18 am

Hi Phil

Sounds like the PSU to me ......... What are you using ?

Dick.
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Re: Noisy eTap2hw

Postby Echotapper » Fri Nov 23, 2012 10:20 am

For noise test the LEVEL pot should be at 50% also to make comparison easier. If the pot is set to 100% the harmonic content could be too much hence being added to the general observation. -Piet
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