Inside the Edirol UA-1EX USB sound card. - diyAudio
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Old 21st April 2008, 11:09 AM   #1
OzMikeH is offline OzMikeH  Australia
diyAudio Member
Join Date: Mar 2007
Default Inside the Edirol UA-1EX USB sound card.

I thought I'd open mine up. I was hoping to bypass the DC blocking caps on the DAC so I can try some better caps by putting them in the cable.

You can search and find what it does and what it looks like so I won't go over it all again here.

The board is riddled with 22uF surface mount electrolytics (18 of them). There are a few 220uF for power supply filtering.
I'm not a fan of surface mount electros, they often leak after a few years.

ADC is an AKM 5537

DAC is an AKM 4385
Summary of the specs of the DAC:
108dB 24 bit 192kHz (only used up to 24/96 in this appication)
128x oversampling.
differential outputs which do not require DC blocking caps.

After the DAC is a JRC NJM2100 dual op-amp, half is used for each channel. I found a datasheet and it doesn't look particularly special, they say: "It is applicable to Handy type CD, radio cassette CD and portable DAT audio apparatus which require the 5V single supply and high output voltage."

After that things start becoming a bit hazy, the traces are hard to follow with the high density components and white silk screening. It is only a 2 layer board so it would be possible to trace the circuit out if you were sufficiently motivated. There are no less than 7 of these NJM 2100 op-amps all over the board. But the UA-1EX has heaps of analog and digital inputs and outputs so I assume they are mainly buffers.

The board is of a reasonable thickness. soldering looks quite good on the larger pads so the sockets shouldn't fracture, but it is lead-free solder which we all know is sheer madness but a political necessity.

After learning this I'm not going to bother modifying my UA-1ex, but chances are someone else will consider doing the same thing I was thinking of doing. So I thought I'd share what I found out.

The device as it is sounds pretty good to me. I've been making a lot of changes elsewhere in my system and I've not listened to very many DACs so I'm not a reliable reviewer.
Help some guys with funny hair bang two rocks together really hard.
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Old 23rd May 2008, 01:37 PM   #2
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Location: Lulea
Did you identify the USB reciver chip? Im searching for a 24/96 capable chip that can output i2s or s/pdif.
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Old 23rd May 2008, 07:13 PM   #3
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My recollection is the Edirol UA-1EX is 24/96 USB compatible. Larry Lavry recommended this product for USB to spdif for his DAC's.

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Old 24th May 2008, 06:11 AM   #4
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Join Date: Jun 2007
Originally posted by agerstrom
Did you identify the USB reciver chip? Im searching for a 24/96 capable chip that can output i2s or s/pdif.
I believe the Edirol UA-1EX uses the Texas Instruments TAS1020B. As does the M-Audio Transit by the way.
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Old 26th May 2008, 06:42 AM   #5
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Join Date: Feb 2007
Location: Lulea
Thanks! From the interfaces supported by the AKM 4385 I would guess they use the i2s that I can tap into.
Big problem with jitter though from the TAS1020B. Especially if it runs in syncronus mode. I plan on using the ESS Sabre as DAC which is supposed to have great jitterreduction.
Guess Ill find out.
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