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solarstabi  
#1 Posted : Thursday, November 27, 2014 12:16:58 AM(UTC)
solarstabi

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My Buffalo 32S/Volumite/LCDPS/LCBPS/Toslink I built in 2009 has been great, used with HD800's wired balanced.
I recently got Westone W30 IEMs to use in bed (sleep on my side).
The Westones are much more sensitive than HD800's, so any noise is very noticeable.
Wired single-ended, I get a hum in left channel.
Rewired the IEMs balanced, & hum becomes a "crackle" in left channel only, very faint, but there.
Volume of noise constant at any Volumite setting, or even with Volumite disconnected.
Changing from Toslink to coax, or even no input, still there.
Tried probing components & the board itself with insulated probe, resoldering some, no indication of source and no better.
Tried running analog section on +-13V LiFePO4 batteries, noise still there.
Originally thought noise went after warmup, but just goes fainter then comes back.
I have run the IEMs on B-II DAC, no noise, so its not them.
Was going to use B32 as DC-powered travel DAC with IEMs, but noise is too annoying.
Can anyone please help me identify which component(s) on B32S board might cause this noise?

Thanks in advance...

Edited by user Monday, December 1, 2014 12:13:46 PM(UTC)  | Reason: Reworded for clarity

Brian Donegan  
#2 Posted : Monday, December 1, 2014 3:35:25 PM(UTC)
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Do you get the same noise when you switch back to the HD800s?
solarstabi  
#3 Posted : Tuesday, December 2, 2014 5:44:15 AM(UTC)
solarstabi

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Yes Brian, very very faint when b32 used with standard 4v rms balanced output.
Before your posting I had decided to install 4 x 2k ohm matched resistors as per manual to reduce output to same as b-II (also so Volumite had adjustment range for IEMs). Hd800s still loud enough for my tastes at that output, & makes comparisons with b-II easier.
Noise in left still there with IEMs, but can't hear through hd800s anymore.
Noise is more like a variable-volume white-noise than a crackle. Varies a bit in volume over time, but independant of volumite level or source paused or playing.
Even tried Toslink module from b-II in b32 - no effect on noise.
Hooked b32 to home amp/speakers instead of b-II (which is absolutely noise-free btw), connected single-ended to amp.
With amp cranked up I can here very faint white noise in left tweeter that's not in right channel.
Interesting it's not a hum as was the case with IEMs single-ended.
Rarely listen to speakers at that volume setting, so would never have noticed if I wasn't listening for it.
But b32 with IEMs when music goes quiet it's there.
For the moment b32 is running amp/speakers with no noticeable noise at normal levels, so I can use b-II in bed with IEMs.
IEMs 30 ohm, 107dB @1mW. Hd800s 300 ohm.
Difference in Volumite setting near minimum vs at maximum.

solarstabi  
#4 Posted : Thursday, December 4, 2014 4:55:19 AM(UTC)
solarstabi

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Just a quick update:
B-II / IVY-III to Westone W30 IEMs is really good. Hours of relaxed listening in bed.
HD800s on same system also good (different to W30s, but I use HD800s sitting, rather than horizontal).

B32 in loungeroom, at normal casual TV/music listening levels, via SE RCAs to amp to NS1000M Yamahas, is fine - plenty of detail & stereo image.
Noise not noticeable at all.
HD800s same as on B-II in bedroom, but not as much listening time to make great comparison.

But W30s on B32 is frustrating. Now that it's in the loungeroom, not likely to be used in that context; but I had plans to make the B32 a travel/portable DAC/earphone amp running on DC. But even running on DC for analog section, noise still there. So can't progress on that evolution without an answer to these questions:

Is B32 faulty? If so, what component(s) likely to be at fault? (without oscilloscope handy, can't measure noise to that level - will try to source one to use)
If not faulty, is B32's design just unsuitable for low-impedance high-sensitivity IEMs like Westone W30s?

Russ White  
#5 Posted : Thursday, December 4, 2014 12:42:24 PM(UTC)
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It could be that the output stage in the B32 does not like that load - you could try adding a small series resistor to the output of the B32 and see if that solves the issue with your IEM. If it does not you may have a AVCC op-amp going south - but that is just a guess.
solarstabi  
#6 Posted : Thursday, December 4, 2014 10:25:00 PM(UTC)
solarstabi

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Thanks Russ, I'll try a small resistor in the first instance. I guess if its A bad opamp I can cut the traces on the board & use an external AVCC.
In that case I may just wait until I get a B-III-SE and bundle the new AVCC with that order.
Thanks...
Russ White  
#7 Posted : Thursday, December 4, 2014 10:43:48 PM(UTC)
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I learned a ton between the B32 and The BIII-SE you won't be disappointed if you go that route. :) I use B3SE/IVY-III (I use this most of the time because I have wired most of my IEMs/cans for balanced use) with several IEMs and my collection of cans from 8Ohm to 600Ohm. If you use strictly SE output the legato with its hefty output buffer on the SE output is a solid choice too. :)
solarstabi  
#8 Posted : Thursday, December 4, 2014 11:57:32 PM(UTC)
solarstabi

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Russ, if I get the b-32 going as a dc-powered travel dac I may upgrade the b-II with new tridents and a new b-III-SE/legato for the loungeroom, still SE initially, but balanced amp might happen eventually.
thanks...
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