Upgrading my AD converter

I was thinking of upgrading my analog to digital converter from the Presonus Inspire to a dedicated AD box like an Apogee AD 96/24 or a Mytek Stereo96 ADC. I could feed the optical out of the ADC into my Focusrite Liquid 56's ADAT input to record the digital output. I'm really happy with the Inspire, but I keep reading all the hype of how much added resolution and sound quality a dedicated AD converter can make. Used Apogee's go for $500 or so used and the Mytek Stereo96 is $895 new. It's really hard to justify the added cost but I really want to be able to capture my vinyl with the highest resolution and quality possible.

Another option is from a new company called Ross Martin Audio. He has a product available called the PCM4222 that is strictly an AD converter based on the Burr Brown PCM4222; a high-Performance, two-Channel, 24-Bit, 216kHz Sampling Multi-Bit Delta-Sigma Analog-to-Digital Converter. The introductory price is $299. It's a small company and the products may look 'hand made' on the outside, but it's what's inside that counts. I only found two reviews and both say the unit's performance is fantastic for the price.

While doing some research, I did find that Mytek has samples you can listen to comparing the Stereo 96 ADC to other high-end studio converters. On a couple forums where studio professionals hang out, there is overwhelming agreement that the Mytek converters are professional quality and well worth the money. Prism, Lavry and Apogee are also revered as being top notch, professional units. People seem to really like Apogee for rock and jazz music mastering. The Mytek is considered detailed and transparent.

There is a used Apogee AD on Ebay right now that is very tempting.

I'll have to do more research before deciding on what to do.   

What about this?
http://www.esi-audio.com/products/drdacprime/
Looks interesting.

What about this?
http://www.esi-audio.com/products/drdacprime/
Looks interesting.

That looks very good for the price. I found a bunch of reviews using it as a DAC, but not many reviews of the recording capability. Looks like it uses an AKM AK5386 24bit/192kHz ADC (S/N ratio 110dB), Burr Brown PCM1796 24bit/192kHz 123dB DAC, and a Tenor TE7022L USB audio controller (96K/24bit). Most of the reviews as a DAC are positive. The price is reasonable too, roughly $460 online. Hmm... 

There is another Apogee Rosetta AD 48K/24bit outboard ADC ending soon on Ebay that I'm tempted to try out. There was a post on www.gearslutz.com with audio samples comparing an Apogee Rosetta with a Motu 828 ADC. The Apogee sounded so much better and the difference was astonishing. I'm really intrigued to see what a studio quality ADC can do with my vinyl recordings. The Presonus Inspire does sound great, but I think compared to a pro level ADC, the difference could be night and day. One of the problems with using something like an Apogee Rosetta is that I would have to run a 40 foot optical cable from where my turntable preamp is, all the way around the room wall to my studio PC's interface on the other side of the room. I would need to connect the optical output from the Rosetta to my Focusrite Liquid 56 interface's ADAT input and use my studio PC to record. Right now, I use the Presonus Inspire interface connected via a short firewire cable to a laptop, located right next to my turntable (to the right hand side, just off camera from in Youtube videos). The only concern I have with that would be if the longer length of the optical cable would cause issues with higher jitter.

An all-in-one unit is more convenient (especially with USB I/O), but I'm leaning towards trying something a little more 'professional' since the benefit of a pro ADC seems relevant after hearing the demos of pro-consumer interfaces demos compared to professional, studio quality units.

There's an Apogee Rosetta AD 48K/24bit converter on Ebay ending in 90 minutes. If the price remains low enough, I might bid on it.

If I don't win that one, there is an Apogee 'Mini-Me' ending later today that does 96K/24bit encoding that looks interesting. There's also a Benchmark ADC-1, but it's the older non-USB version, which I wouldn't need anyway since all I need as ADAT digital output.

I think I would prefer the Apogee first since the sound quality of Apogee units are second to none in the realm of professional studios (except new Apogee units!). If I can't get an Apogee at a decent price, I may go for a Benchmark ADC-1, RME ADI-2 or the Ross Martin.

I do know that even recording at 96k/24bit with my Presonus Inspire, the recorded files of my turntable don't sound quite as good as hearing it live, so there must be some loss of quality. I imagine an Apogee Rosetta running at 48K/24bits will sound much better then my Inspire @ 96k/24bit.

Well, I won an Apogee Rosetta AD 48K/24bit AD converter for $325. I'm going to try it first by sending the audio via optical cable to my Focusrite Liquid 56 interface.

This is going to be very interesting to see how much better a pro level converter sounds over the Presonus Inspire. 

It turns out the Apogee Rosetta I just won is from this person - Frankie Spellman.

According to him, it was used for various TV and movie soundtrack projects, including a movie called 'Hats Off'. Interesting.
He has samples of the soundtrack here.

These are highly compressed samples, but it does sound good. This is going to be very interesting.

[attachimg=1]

Ok, so maybe I jumped the gun a little by buying an Apogee before digging deeper into AD converter technology first. 

It looks like TI's PCM4222 chip is the current, premium, top of the line AD chip on the market today. From what I read, it's cleaning the clocks of all the previous chipsets and technologies in head to head testing. In subjective sound quality comparisons, studio engineers are choosing the PCM4222 chip over most other designs.

After digging a little deeper, it looks like the Ross Martin PCM4222 ADC is one of the best implementations of the TI PCM4222 chip. According to Ross, one of the first units he built went to Sony studios for evaluation. They were so impressed by it, they kept it and asked him to custom build a 16 channel to 32 channel ADC/DAC for their studio.

After discussing my needs for unbalanced inputs and the output format compatibility of the optical output, I decided to place an order for a PCM4222 ADC. 

So, it looks like within two weeks I will have both ADC units here for testing. I'll post samples of both units when the arrive.

I received the Apogee Rosetta the other day and it sounds amazing! Checkout the samples here: http://www.vinylaudio.net/forum/index.php/topic,234.0.html

I just received an email from Ross Martin on the status of my order - the case for my PCM4222 ADC was CNC cut on Tuesday, the unit was hand assembled on Wednesday, and will head to the bench for testing on Thursday. If everything checks out, it will be ready to ship by the weekend. All of Ross Martin products are hand built only after they are ordered, which allows for modifications and customization by the customer.

Meanwhile, I received my 50 foot(!) optical cable to connect my Apogee Rosetta to my studio PC on the other side of the room. I also bought a pair of rack mounts and some wood; I plan on building a custom 2U rack under my turntable to house my analog-to-digital converters. That way, I can directly connect the output of my PH5 preamp to the inputs of the Rosetta AD, keeping the signal path and cable distance short. Plus, I can easily connect my Revox A77 reel-to-reel to the Apogee Rosetta to record it.

Update: According to an Email from My Ross Martin, my PCM4222 ADC will be shipped tomorrow. 

Also, the 50 foot optical cable was a bust - the signal was so weak on the other end that my recording interface could not lock on to the signal. Visually, the red 'laser' light was about half as bright after passing through 50 foot of cable, which is most likely caused by poor construction (bad termination) or inferior fiber quality. I contacted the Ebay seller and he agreed to refund my purchase.

Instead of using an optical cable, I decided to go with two coax cables; one for the digital signal (RCA to RCA) and one for the clock signal (BNC to BNC). The clock in the Apogee Rosetta is supposed to be very accurate, so using two cables allows me to sync the clock on my Focusrite Liquid 56 to the Rosetta. The two cables will also work with the Ross Martin ADC and my Panasonic DAT recorder.

Tomorrow I plan on placing an order for a Ross Martin DAC with headphone output once I get the confirmation that the ADC has shipped. Ross offered a reduced, combo price for the DAC since I purchased the ADC, so I couldn't resist.

I'll post an update with some audio samples when I get the PCM4222 ADC.

So, generally speaking, you feel that an ultra-high quality 48kHz DAC is better than a lower quality 96 kHz DAC?

So, generally speaking, you feel than an ultra-high quality 48kHz DAC is better that a lower quality 96 kHz DAC?

That's a hard question to answer. From my experience, there is a difference in quality between products targeted to consumers and products made for the professional market. But then again, each piece of gear has unique and audible 'character' traits, not matter how small, that sets it apart from the competing products.

In the case of the Presonus Inspire vs the Apogee Rosetta, the difference are not 'good vs bad', it's really a matter of taste or preference.

The Inspire, with the AKM chipset, has a softer overall sound compared to the Rosetta. The Rosetta has a more forward sound, with a slight emphasis on the midrange. The Inspire can sometimes get 'overwhelmed' when the music is dense and dynamic, which can make it sound a bit compressed. The Rosetta has no problem at all keeping each instrument in check when the music becomes dynamic and complex.

Compared to the Rosetta, the Inspire has a limited range of dynamics (or peak volume) for the inputs; which means it's pretty easy to overload it with a 'hot' signal. My Audio Research PH5 preamp has very sensitive inputs so it can handle very low output moving coil cartridges. If I feed it a signal from a high output moving magnet (3mv or higher) cartridge, the output would be too high for the Inspire to handle and it would clip and distort. The Rosetta has a much wider acceptable range, with a switch for -10db (consumer grade) to +4db (pro grade) on the XLR inputs, plus each channel is fully adjustable with potentiometers accessible on the front. The Inspire's input range is preset at the factory and is hard wired. You do have some adjustment with the software, but you are actually adjusting the gain, not the actual signal level before it hits the A/D chip.

Overall, the needs and expectations are different between consumer and professional users and the products tend to reflect that difference.

What's really going to be interesting, is how the Ross Martin ADC compares to the Inspire and Rosetta. Ross sent me an email with the tracking # and the PCM4222 ADC should be here tomorrow.   

Ok, I received the Ross Martin PCM4222 ADC yesterday, and I got a chance to look it over and try it out.

My initial impressions:

     • Not enough gain on either input (XLR or 1/4") for recording my Zyx Omega G, even with the gain knobs maxed out. 
     • The sound quality is about equal to my Presonus Inspire with the Inspire sounding 'quicker'.
     • Bass seems to have less weight than the Apogee Rosetta and Inspire, but that could be caused by the gain issue.
     • Master and word clock outputs don't work, or the signal is too weak for my Focusrite Liquid 56 to lock onto the signal using a 35 foot coax cable.
     • The fit and finish is very 'home made', but in a good way. I actually like the simple look and construction.
     • One of the XLR input connectors is cracked, right out of the box.
     • No removable power cable - it's hard wired to an external 'brick' transformer.
     • Low level hiss present, even with the gain all the way down. The Apogee has zero noise and a pure black background when no signal is present.
     • The front level meters are not calibrated to the digital output, 0dB on the front meter is -3dB on the digital input on my Liquid 56 coax input.
     • Left to right channel balance is very good, within .2dB

Overall, I wouldn't say I'm disappointed - it sounds very good, but it's not exactly what I expected. The gain problem is a big issue for me. The word clock problem is another big issue that I need to work on. The sound quality is not as precise as the Rosetta.

While I was testing it yesterday, I thought about Ishin80's question on 48Khz vs 96Khz DAC's and I'm starting to think that sometimes, higher bit rates don't always translate into higher quality audio.

     • The Apogee Rosetta AD @ 48Khz / 24bit is the best A/D converter I ever heard, period.
     • The Presonus Inspire @ 96Khz / 24bit sounds fantastic for the price.
     • There is a slight sound quality difference between 48Khz and 96Khz on the Inspire, with 96Khz being the best. But even @ 96Khz, it doesn't beat the Rosetta @ 48Khz.
     • The Ross Martin sounds very good @ 96Khz but slightly different than the Presonus Inspire.

So, in other words, a high quality 48Khz A/D converter with excellent engineering and attention to detail, can sound better then a lower quality A/D converter running at a higher bitrate.

I'll try to record some samples of the Ross Martin and post them later tonight.

Here's a few pictures of the Ross Martin: