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Offline renedebos

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SPDIF connections
« on: March 11, 2022, 03:15:44 PM »
Currently I am transferring DAT tapes to my laptop USB using the following :

TASCAM DA-40 -> Spdif Coax to ROOFULL Coax to Spdif Optical converter -> Spdif optical to HIFIME UR23 optical to USB converter -> Laptop USB port

I want to use a bit bucket rather than occupying my laptop but it has been a pain to find a bit bucket that can be used with spdif. I have a M-Audio Microtrack II on the way.

Hifime now has a new product called S2-Digi that might make life a bit simpler... but I am not familiar with this product and am quite a noob when it comes to gear. Not sure if I am understanding this new gizmo right.

https://hifimediy.com/product/s2-digi/

Anyone use this product and if so would I be able to use this to connect my DA-40 to this S2-Digi and then plug it into a solid state recorder (Tascam, Sony, Zoom) that has a USB input? I am in the market for a new handheld recorder and wondering if there the use of USB would make options easier to find and at the same be able to use it for transferring DAT tapes.

Apologies if I am completely misunderstanding this S2-Digi... just starting to work on archiving a box of DAT tapes and it is making my head hurt.

Offline commongrounder

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Re: SPDIF connections
« Reply #1 on: March 12, 2022, 07:27:56 PM »
I’m sorry to say, the S2-Digi will not work with the USB port on a digital recorder, with rare exceptions. The S2 is a peripheral device and a digital recorder is also a peripheral. One of the connected devices needs to be a usb host capable device, like a computer, tablet or phone. I believe the best solution for you will be to buy a digital recorder with a direct coaxial digital audio input. The ones that come to mind are the Tascam DR-100 series machines. They have a 3.5mm digital input that can be adapted to the cable you are using to connect to your DAT machine. No optical conversion necessary. The DR-100 series is discontinued, but the mkiii version is still available here and there new, and is a great handheld recorder in general.
Best of luck!

Offline rocksuitcase

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Re: SPDIF connections
« Reply #2 on: March 13, 2022, 06:21:27 PM »
PMD661 has digi spdif in
music IS love

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Offline goodcooker

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Re: SPDIF connections
« Reply #3 on: March 14, 2022, 12:08:41 PM »

I use a Tascam DR680 for SPDIF DAT transfers. You could also use a Marantz PMD661. Either one should be very straightforward and be plug and play as long as you have the bit and sample rate to match the source. I considered using a Marantz 580 since I have a gear rack but the CF card as opposed to the SD cards I have laying around already didn't jive. They are cheap though - around $100 all day long on resale sites.

Keep an eye on ebay or Reverb for inexpensive used units. They can be had for less than $200 for the DR680 and less than $150 for the 661 if you are patient.

During the pandemic I transferred a bunch of tapes and used a SD USBPre to an unused Win7 laptop and I found it easier to keep things organized and labeled but since I moved to the DR680 I just had to change the way I took notes then transferred the files from the SD card into folders on my machine. Took a little time to get the hang of it and at first it was challenging. The more you do it the easier it gets. Realizing I had to take notes of the numbered files on the recorder was the key to staying organized.
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Offline flex

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Re: SPDIF connections
« Reply #4 on: March 16, 2022, 04:48:07 PM »
I'm a very long time lurker here and this is my first post after becoming a member.

I used the Microtrac II as a bit bucket for years until it gave up the ghost. I wouldn't recomend it unless you get one for free. I loved it, but it's hopelessly out of date. The electronics never failed but the chassis and the case are not so durable. And by now the batteries are shot from age alone.

I currently use a like-new DR-100 mkIII. The sound is great, but I'd like something newer with a lower noise/distortion floor. Still can't fault the mkIII though. I build custom mics and get some real nice recordings from the mkIII.

I have a question regarding using any recorder as a bitbucket. If I send a digital signal into the spdif port on the DR-100 mkIII, or any other recorder with digital in, does the signal go through an A/D conversion? Or is it common for the serial digital to simply be transformed into a (wav or other) file format strictly in the digital domain?

Couldn't find an answer on the forum, even in the DR-100 thread, or on the web, and thought I could squeeze the question into this thread since it relates directly to using a recorder as a bitbucket.
 
But if I'm hi-jacking just thunk me on the head.

Offline goodcooker

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Re: SPDIF connections
« Reply #5 on: March 16, 2022, 08:09:15 PM »
Other spdif input recorders to consider are

Tascam hdp2
Marantz pmd 670 or 671
rig in transition during temporary hiatus

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Offline flex

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Re: SPDIF connections
« Reply #6 on: March 17, 2022, 07:23:17 AM »
Given the OP's desired outcome (DAT to archived pc file) I thought I'd share some previous experience.

Coax spdif has challenged me with noise and dropouts. Many recorders do not have isolation transformers that provide galvanic isolation. Your DAT machine may not have isolation transformers on the coax output. Also, coax cables are not created equally. Some are useless. Here's what I've done in the past:

Using the Microtrac II which if I recall is not isolated due to board space, I sent digital audio to it via an old EMU 0404 interface that IS isolated on both coax in and out. This is a USB audio interface that's not well thought of within the music recording crowd but does have some nice A/D's and D/A's. The board design is really top notch. The packaging is cheap plastic though. It has a low noise floor and is quite stable on USB. Using an 0404 interface would allow you to plug your DAT source directly to the pc via USB and transfer 24/192 pcm to wav files. The 0404 is pushed to it's limit at 192khz though. 24/96 is better.

You might find one of these EMU 0404's on fleabay for cheap. Maybe.

Another thing that's bitten me in the behind is USB noise and artifact. I use a cheap USB isolator ($21.95 on amazon) to isolate the pc from my interface or
dac. You can spend hundreds for an iFi USB isolater, or get the same thing without the fancy name for $21.95 - it uses the same chip. I've tested this USB isolator up to 24/96 and it works just fine. Am listening to my dac streaming 24/96 flacs from Qobuz through the isolator at this moment with no problem. Gorgeous sound and deep black silence with perfect galvanic isolation. No more USB noise.

If for some reason you decide to use toslink, amazon has inexpensive glass cables instead of plastic. I think the brand name is Glass. A glass fiber optic cable will make a world of difference if the optic transceivers on both ends are decent quality. Hi-Res audio can be connected via regular toslink with these glass cables and no distortion or latency will be introduced.

I once fought all of these coax and USB noise problems by designing and building a 4in/1out selectable spdif box using coax. Digikey has the transformers. Standard 74HC logic chips and digital MUX are used. The circuit is simple but you must use a fully isolated power supply. I've got the schematic kicking around somewhere. My digital scope has lots of memory so I can capture complete coax signal 'frames' and compare to the clock to do jitter measurement. Wish I had a logic analyser. The signal coming out of my spdif selector/isolation box is as jitter free as the signal going in.

I routinely use lithium ion power bricks to run each device chained together since all my gear is mostly portable. Amazon has some nice little power supply filter boards that are very inexpensive. These can filter your power bricks even better than the internal filters and only drop the output voltage (nominally 5vdc) by millivolts.

My DR-100 mkIII has a similarly sized power brick permanently attached to the back. Nice thing about the
DR-100 mkIII is that you can record while feeding it USB power. No sound quality is lost. Yes, it's bulky for stealth recording. I feed the DR-100's line out into an AudioEngine W3 wireless transmitter powered by another 'sandwiched' power brick on the recorder. I throw the recorder package into a backpack and monitor using in-ear headphones (Etymotics of different varieties) driven by various FiiO headphone amps (E12A. Q1 mkII) that are fed by the little AudioEngine W3 receiver. The W3 audio link is good for totally uncompressed 16/48 with about an 85db noise floor and extremely low latency for a wireless link - far better than the best bluetooth link. I can walk away from the backpack with the recorder and mics and still monitor. To onlookers it appears that I'm listening to an iPod with ear buds.

I could kick myself in the butt for not buying the Texas Instrument development kit for setting up the CC8520 PurePath chip family when it was available (used in the W3). These chips are still available for about $6 each. They are a complete audio link 'system on a chip' that can be run standalone without microprocessor contol. I'd love to build these links into custom gear to run audio cable-free and still have a crystal clear very low latency signal.

Isolation is key to good coax transfers. Same with USB to/from the pc. If the anyone uses one of those old 0404 interfaces with a USB isolator, make sure the power supplly to the 0404 is isolated as well. It does not use USB power. Other audio interfaces with coax in and out are certainly available but at a fairly high price.

I'm still curious if the DR-100 mkIII does a D/A - A/D conversion on the incoming coax signal before writing the file. I saw somewhere on this forum that a member was able to get schematics for the DR100 mkIII but I can't find that post again. Does anyone have even a block diagram of the DR100 internals? Tascam isn't too helpful since it's an obsolete unit.

Offline Gutbucket

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Re: SPDIF connections
« Reply #7 on: March 17, 2022, 10:56:31 AM »
I have a question regarding using any recorder as a bitbucket. If I send a digital signal into the spdif port on the DR-100 mkIII, or any other recorder with digital in, does the signal go through an A/D conversion? Or is it common for the serial digital to simply be transformed into a (wav or other) file format strictly in the digital domain?

No ADC in the signal path when using the digital in (or DAC when using digital out).

Quote
I feed the DR-100's line out into an AudioEngine W3 wireless transmitter powered by another 'sandwiched' power brick on the recorder. I throw the recorder package into a backpack and monitor using in-ear headphones (Etymotics of different varieties) driven by various FiiO headphone amps (E12A. Q1 mkII) that are fed by the little AudioEngine W3 receiver. The W3 audio link is good for totally uncompressed 16/48 with about an 85db noise floor and extremely low latency for a wireless link - far better than the best bluetooth link. I can walk away from the backpack with the recorder and mics and still monitor. To onlookers it appears that I'm listening to an iPod with ear buds.

I could kick myself in the butt for not buying the Texas Instrument development kit for setting up the CC8520 PurePath chip family when it was available (used in the W3). These chips are still available for about $6 each. They are a complete audio link 'system on a chip' that can be run standalone without microprocessor contol. I'd love to build these links into custom gear to run audio cable-free and still have a crystal clear very low latency signal.

This is very interesting stuff. Long ago I dreamed of a similar setup for Ety's or other highly isolating in-ear monitors that would work for monitoring while recording, yet could also serve stand-alone as an "smart ear-plug / active hearing protection" system.  In that role it would include filtering to shape the "as heard" response, correcting for the non-flat attenuation of the ear-plug response and bone-conduction, ideally including an active low-frequency cancellation circuit, similar to active noise cancellation headphones but with way more low-frequency cancellation headroom.  At those long wavelengths, it might be able to use the signal from the recorder for the active low-frequency cancellation (rather than small mics on the earphones or on the receiver/amplifier to which they are attached) as long as you don't wander too far away.

Other spdif input recorders to consider are

Tascam hdp2
Marantz pmd 670 or 671

Also Roland R-44

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Offline flex

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Re: SPDIF connections
« Reply #8 on: March 17, 2022, 02:51:30 PM »
Thanks for the feedback on the DR-100 coax input. I do get some great recordings via the coax on that unit.

The ety's already do the hard work, compensating for human ear linearities, etc. When my mics are set up binaural and I'm recording it's like I'm listening with my ears, no electronics involved. But I'm not a real audio engineer. My thing is psychology and sleep research. Or it was until I retired. So my electronics background is focused on designing specialized EEG amplifiers for research along with hard-core data acquisition. Used to run a metrology lab somewhere back in history, designed and built the data aquisition system for testing and validation of the Titan IV rocket launchpad components, then did medical device engineering for a day job. Audio electronics is for me a passion for sound itself. My ears are my primary sensors. And music is an essential part of my life.

I like to build mics that can 'hear' what my ears hear, i.e., provide a signal that replicates what I hear normally. Of course we know microphones cannot quite match our ears. But they can come close. In my experience most people do not use their ears properly. Detail tends to become filtered by the brain automatically. It's the brain filtering that needs to be tweeked more than anything else. Just my two cents. Consumer electronics is dependent upon brain filtering to create a sound that seems like it's real but it's not. It's called compression. Trained ears are repulsed by it.

Last I heard AudioEngine had some W3's remaining on amazon. I purchased another set recently. The case can be opened if you're careful and longer USB cables soldered in for attaching the unit to a recorder with 3M sticky tape. The boards themselves are very well designed and the circuit represents the simplest implementation of the chips possible. The transmitter requires little current at 5vdc. The receiver even less. Some 5v power bricks require a resistor to be added in parallel to boost the current draw above the point where the power brick senses that there's actually a load. Otherwise the power brick won't run. Just a few milliamps is necessary. The analog signal in and out is in the range of 2v, not sure if that P/P or RMS. The W3 response is suprisingly linear.

The W3 circuit boards can easily be remounted inside other gear and not have to be an addon. It is incredibly unfortunate that the W3 has been made obsolete. The TI chipsets were not a success on the market because they cost more than cheap bluetooth chips. The market in this case is stupid. Paying just a little more for uncompressed sound is too much for the market to bear. Bluetooth had to be compressed and tweaked just to provide the minimum latency necessary for watching a DVD movie or streaming video online. The TI chipset in the W3 is so close to being a wired connection that in most cases it is transparent. In my home I use Ety ER4PT's with a FiiO amp and a W3 receiver in my pocket to listen to everything, pc's, music server, etc. while I work or putter about. Up to three receivers can lock onto one transmitter.

Now I sound like I'm a bloody shill. Well, maybe I am when it comes to innovative semiconducters that should have become mainstream.

Are we off topic yet?

 

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