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Old 14th September 2010, 12:36 AM   #1
ggking7 is offline ggking7  United States
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Default Perfecting the USB Isolator

I've been using the DIY Paradise Ultravox (ADUM4160) to isolate the USB connection between my DAC and computer:

Ultravox - SGD70.00 : Welcome to the diyparadise e-store!

The Ultravox and downstream DAC are powered via an SLA battery connected to the Ultravox. There are a couple problems with this setup and I'd love to get your advice on fixing them.

Downstream USB Connection:
The USB connector on the DAC side of the Ultravox is a female A type and the DAC has a female B type. I've been using a USB cable between the DAC and Ultravox but I'd rather plug them together directly. To do that I need to replace the Ultravox's female A connector with a male B connector but I can't find a USB male B connector anywhere. Do they exist?

Power Supply:
I tried switching from the SLA battery to a series of AA NiMH batteries and the sound was substantially worse. The sound was overall much weaker and thinner and lacked bass. That makes me think I could do better than the SLA battery with a very quiet linear power supply. Does anyone know of an available linear power supply which would be suited to this?

Miscellaneous:
Can anyone with audio DIY experience spot any other possible upgrades or improvements that could be made to the Ultravox. Maybe replace the capacitors with Black Gates? Thicker power leads?
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Old 14th September 2010, 12:59 PM   #2
erin is offline erin  Australia
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USB Cable of My Dreams « Circuits@Home

http://www.circuitsathome.com/mcu/us...asked-question

check this out. should answer some questions

Any linear power supply should be OK.

Black gate capacitors are best used in analog circuits not digital.

Last edited by erin; 14th September 2010 at 01:01 PM.
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Old 14th September 2010, 01:48 PM   #3
qusp is offline qusp  Australia
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even then i'm of the opinion that BG can be fairly easily bested; this whole thing of just dropping them in anywhere without regard to what the purpose is confuses me. but yes for digital supply decoupling and bypassing, they arent even in the picture IMO. oscons, polypropelene or pps films and npo ceramics are much better choices for digital circuits. even panasonic FM or other really low Z electrolytic
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Old 14th September 2010, 02:34 PM   #4
wwenze is offline wwenze  Singapore
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Looks to me that the Ultravox has a linear regulator onboard. Do away with that if you're using your own linear regulator and test the power sources again.
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Old 14th September 2010, 07:35 PM   #5
ggking7 is offline ggking7  United States
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Quote:
USB Cable of My Dreams « Circuits@Home

check this out. should answer some questions
I have one of those adapters but I can't get it to pass USB power, only data, so it doesn't work with USB-powered devices. Do you know if a solder-able USB male B connector exists? That way I can plug the Ultravox and DAC straight together.

Quote:
Black gate capacitors are best used in analog circuits not digital.
Well I was told to use Black Gates for this by the head engineer of a very well-known DAC manufacturer. Plus there are forum posts at DIY Paradise which report an increase in sound quality when the capacitors are switched for Black Gates.

Quote:
Looks to me that the Ultravox has a linear regulator onboard. Do away with that if you're using your own linear regulator and test the power sources again.
That sounds like a good idea. Can anyone recommend a small but very low-noise linear power supply for this? I don't think I'll be able to build one, but an assembled kit would be great.

I'm also going to try switching the SLA battery for Lithium-Nano-Phosphate batteries:

EP Buddy 3S1P 9.9V 2300mAh LiFe battery pack USA A123 - eBay (item 230442131487 end time Sep-22-10 17:40:21 PDT)

I think they should have better current capabilities than my SLA battery and hopefully lower noise. Plus they should recharge in about 15 minutes as opposed to 15 hours.
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Old 14th September 2010, 11:27 PM   #6
erin is offline erin  Australia
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Quote:
Originally Posted by ggking7 View Post
I have one of those adapters but I can't get it to pass USB power, only data, so it doesn't work with USB-powered devices.
Have you measured the volts on the pins? Have you checked the datasheet so you understand how the isolator works?

Are you sure the chip does not need to be reset to "wake it up" as described on the circuits at home website?

Quote:
Originally Posted by ggking7 View Post
I think they should have better current capabilities than my SLA battery and hopefully lower noise. Plus they should recharge in about 15 minutes as opposed to 15 hours.
My SLA battery recharges from flat in about 20 minutes.
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Old 15th September 2010, 03:36 PM   #7
ggking7 is offline ggking7  United States
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Quote:
Have you measured the volts on the pins? Have you checked the datasheet so you understand how the isolator works?

Are you sure the chip does not need to be reset to "wake it up" as described on the circuits at home website?
I was wrong when I said my USB gender changer did not pass power. It does, although it didn't the last time I checked for some reason. The problem is that it sounds worse than my 1 meter Wireworld Starlight USB cable. I think it's because the gender changer has one or more bright LEDs that light up when it's powered. I think that must be adding noise to the signal and/or power. I've seen just about every other type of solder-able USB connector except for male type B. Does anyone know if they exist?

Quote:
My SLA battery recharges from flat in about 20 minutes.
I've never heard of an SLA battery charging so fast. What is its capacity and what are you using to charge it? Mine is 8Ah and I'm using a cheap 2 stage charger.
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Old 15th September 2010, 03:52 PM   #8
ggking7 is offline ggking7  United States
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I did find these:

20Pcs USB Type-B Male Plug Connector Socket For DIY - eBay (item 170520488212 end time Sep-27-10 07:40:15 PDT)

10Pcs USB Male Type-B Plug Connector Socket For DIY - eBay (item 180539614008 end time Sep-27-10 08:56:54 PDT)

Should I be able to replace the USB connector on the Ultravox below with one of the above?

Ultravox - SGD70.00 : Welcome to the diyparadise e-store!
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Old 20th September 2010, 09:32 AM   #9
qusp is offline qusp  Australia
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Quote:
Originally Posted by ggking7 View Post
Well I was told to use Black Gates for this by the head engineer of a very well-known DAC manufacturer. Plus there are forum posts at DIY Paradise which report an increase in sound quality when the capacitors are switched for Black Gates.
sorry but just because he is an engineer in an audio firm does not make him right in this instance. some people report increased sound quality when using massive NOS oil caps with huge long inductive leads for decoupling digital clock supplies too.

some people say BG are great for just about anything, the simple fact is they have high impedance at the high frequencies needed for decoupling digital circuits.

get the real deal lifepo4, not cheap ebay ones. get A123 they are fantastic and beat out any low noise regulator I have tried and I have tried many. if batteries are convenient, then I whole heartedly recommend them. the real A123 have larger capacity, last for much longer and have much higher current capability.
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Old 20th September 2010, 10:06 AM   #10
erin is offline erin  Australia
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Quote:
Originally Posted by ggking7 View Post

I've never heard of an SLA battery charging so fast. What is its capacity and what are you using to charge it? Mine is 8Ah and I'm using a cheap 2 stage charger.
I'm using a 1.2Ah SLA from here:
RPG - SXKK0525 - SEALED LEAD ACID
I think it charges fast because its only 1.2Ah

The charger I use is also from Radio parts here:
http://www.radioparts.com.au/ProdVie...RICKLE+CHARGER
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