AD/DA Converters and Preamps

Euphonic Studio
Mount Vernon, Iowa
Serving the Cedar Rapids-Iowa City Corridor
Call 319.895.8002 for a tour or recording appointment or write
We record all types of music and your satisfaction is guaranteed!

How Euphonic Studio Chases the Sound

So much gear, so little time….

This page is about the equipment that turns complex electrical waveforms that are picked up by mics and instruments into analog and digital signals.  The reverse process is used to turn the data into sound waves.  The conversion of sound into data is called sampling.


AD/DA and integrated preamps

RME Fireface UFX

This is arguably the finest piece of its type. The “gold standard” for AD/DA is the Apogee Ensemble, which costs 3 times as much. Many engineers who have done side-by-side comparisons say the RME is as good as the Apogee, just different.

I chose the RME Fireface UFX based on the recommendation of my Sweetwater sales engineer and he gave me some great advice.  I wanted a unit that was the highest quality AD/DA conversion that I could afford and this piece oozes quality.  With expansion cards over ADAT, it records 24 clean and jitter-free tracks at 44.1K and 16 bits.  If you want higher quality and can get by with less simultaneous tracks, it will record at 192KHz at 24 bits with 4 channels at a time.  It works very well for me, and many engineers who have used this piece compare it favorably or equivalently with the Apogee Ensemble, which is considered to be the “gold standard” in AD/DA converters.  Some say it’s equal quality, just different.  And the Apogee costs 3 times as much.

For you total gear freaks out there, here’s a review excerpt from Sound on Sound:

RME’s converters have always been a step above the average, and the UFX uses a similar A‑D converter stage to RME’s high‑end ADI‑8 QS preamp and converter (based on a Cirrus CS5368 IC), with a dual‑parallel converter arrangement to achieve unusually high signal‑to-noise performance figures. The D-A stages are derived from those used in the RME M‑Series products (using a Burr‑Brown PCM4104 chip). In the UFX, these achieve a signal‑to-noise ratio of an impressive 118dB A‑weighted, with a THD+N figure better than ‑100dB — both being excellent figures. The A‑D side boasts an impressive performance too, with a signal-to-noise ratio of 115dB (A‑weighted) for the mic inputs.

In case you can’t exactly follow that text, what it’s saying in plain English is “These converters ROCK!

Rear View of RME Fireface UFX

Rear View of RME Fireface UFX. This shows the connection points for most of the I/O including the clock and ADAT.

The Fireface UFX is the host for the outboard part of my system.  It has 8 in/8  line out on the back panel plus 4 preamp inputs  in the front.  The preamps inputs on the front are great to have if you are using the piece as a stand-alone recorder, which it will do with the simple addition of a memory stick.  The company counts the I/O at 56 or something like that.  Technically they are correct but that is misleading because the clock inputs and outputs are not usable for musical program.  For example, the firewire that connects to my DAW is essential for operation but it’s certainly not available to plug a mic into.

The standalone recorder is very handy if you are comfortable letting it out of your rack.  Perhaps you’ll buy a second one for live recording.  You don’t need a computer to run it.  You can plug up to a 2 TB USB drive into the front panel and it will record directly to it with no computer at all.

UFX TotalMix

UFX TotalMix, the most versatile software soundcard interface imaginable. With this software and the Matrix View you can route any input to any output, create custom monitor mixes, and use the DSP to clean up or add effects for the singers and musicians.

RME has provided this piece of equipment with a superb software application called

Totalmix Matrix View

Totalmix Matrix View. You can toggle between this view of your RME software mixer or the more traditional one. This is like having a patch bay at your command. You can easily send any input or playback to anywhere.

TotalMix to control and monitor it.  You almost have to see it and use it to believe it.  It is by far the most versatile hardware control I’ve ever seen.   It can be used to control all the sound cards on your Fireface ADAT network.  The Matrix view is just out of sight!  You can plug any input or playback into any output just by clicking a square on a grid.  It doesn’t stop there, either.  TotalMix has a compressor, an EQ, and reverb and echo that can be recorded or just used for headphone mixes during recording.  Oh, and speaking of headphone mixes… Totalmix provides the capability for 16 different headphone mixes.  This is a well-designed software application.

I mentioned the 8 channels of line in that form the high quality converters for my studio. So where do the other 16 hardware I/O  come from?  Well, the Fireface UFX has two ADAT ports, both having input as well as output, so you can extend your inputs and outputs with additional cards via optical cabling.  ADAT is a standard developed by Alesis.  Most gear of this type connects via optical cabling.  I have two additional cards, a Focusrite Octopre and an Art Tube Opto 8.

The Focusrite Octopre is an 8 in/8 out card that has 8 channel preamps with compressors built into it.  You can turn on phantom power in groups of 4 channels.  The compressor is extremely simple to use; with 1 knob it would have to be: most compressors have at least threshold, attack, release, and ratio.  It has a preset attack time of 1.2 ms and release time of 28ms.  If you look at the curves in “Normal” and “More” modes, you can see that the upper right hand square where the level crosses 0 dBFS, it’s off.  I’m not sure if this means that the card functions as a brick wall limiter but it sure does act like one.

Octopre front-back

Focusrite Octopre front and back. If you are recording drums a lot I would highly recommend one of these as a relatively inexpensive set of 8 preamps and AD/DA converters. They connect via ADAT.

For instance, I have found the Focusrite Octopre to be extremely useful for recording drums.  I have had a couple of loud drummers in the studio, and even though the LED meter stacks on the right side of the card are pegging there is NO digital distortion!  I have been amazed by this more than once.  As far as the notion of “Focusrite quality” goes, however, the sound of these preamps bears no resemblance whatsoever to the sound of the Focusrite ISA 428 (see below).  This ought to be a good thing to bear in mind when you see advertising copy that says things like “built in the tradition of Focusrite” or whatever verbiage is used.

Tube opto 8 front-back

ART Tube Opto 8. This is the cheapest 8 channels of ADAT preamps I have in my rack. They are OK but you have to be patient to find the best setting for them because they are twitchy. It’s not bad for entry level but usually people at entry level won’t be patient enough to learn the piece.

The ART Tube Opto 8 was my first purchase of AD/DA equipment and I didn’t even use it for that.  At the time, I had just upgraded to M-Audio Delta 1010 cards and since those were line in I needed some cheap preamps.  The Opto 8 has an unintended plain preamp function available.  You can plug the ADAT input into the ADAT output and you have 8 preamps with a 1.2 ms delay through the converters and back out of them. Yes, it sounds goofy, but 8 channels of “tube warmth” preamp for $300 sounded pretty good to me at the time.

My impression of the Tube Opto 8 is that it’s really not a stinker of a piece of equipment, but it is hard to set properly and there is no software interface to help plus the metering is horrible.  The big sales point of it is that it has a “warmth” knob to allow you to dial in tube distortion, the supposed holy grail of digital recording.  (Free hint:  It’s not.)  If you are patient you can get these preamps to do a passable job but if you consider that you’re working with a piece that’s about $35 per channel including AD/DA converters and ADAT MUX/DEMUX plus a clock, your mileage my vary.

Now let’s move along to the freestanding preamps.  First up is the Focusrite ISA 428 which came highly recommended to me from a helpful voice on Gearslutz forum.  Now you can’t believe everything you hear from strangers, but when they person has over 12,000 posts and links to a well-known British recording studio, it lends a bit of weight to their opinion.  So I found one on eBay and forked over an amount that was about 5 times more than I wanted to pay for any piece of gear ever (little did I know).  When it came in I was immediately in awe of the way it looked and felt.

Focusrite ISA 428

Focusrite ISA 428. This is one of the sweetest pieces of gear in the studio. It has an extremely clean sound but also can be altered. An added plus is the insert on each channel. You can add an optional 4 channels of AD/DA converters. Don’t be fooled by the “Mark II”. It’s been downscaled.

My first opportunity to record vocals with the Focusrite ISA 428 was as a follow-up project to the spring high school musical, High School Musical.    The best mics I had at the time was a pair of Rode NT-1a and the preamp was going into a M-Audio Delta 1010.  I think I still had a Dell P4 running Sonar 5.  They were singing along to the original soundtrack from the show so it was a fairly easy job to get several songs recorded.  I was very impressed with the versatility and the quality of the 428.

So impressed, I bought a second one, so I have 8 channels of top quality preamps which also works for a spare.   There are simpler, cheaper, utilitarian preamps that are a lot less money, but those don’t come close to the versatility of the ISA’s  front panel controls.  It’s obvious that Rupert Neve had a hand in the design.  There are a variety of gain-related controls that give you very granular gain control up to 80 dB of transparent, beautiful, sound.  There are 4 input choices for each channel,  actually a selection of 4 different different input impedences ranging from 600 omega to 6800 omega.  The input impedance of the preamp has a different effect on each microphone; the selection of these plus the low end rolloff control give you an amazing toolbox to find a best sound for any mic you connect.  No matter what you have in your mic locker, when you plug it into a ISA you will find settings that will make it sound as good it can.


ART Tube PAC, an OK preamp that will do in a pinch. These feature built in tube compression and overdrive for that “warm” analog sound. OK, whatever. I mostly use these to overdrive the input on my Twin to get it to distort without having to crank it up to enough to wake the dead.

Having an ISA 428 plus the 4 inputs on the UFX, I have the small session pretty well covered.  I also have some other preamp choices.  I have 2 ART Tube PAC units, which I thought were pretty much OK when I bought them.  The price of these went down drastically; when they were new they were $300 and I think I got the second one for $75.   This is another one of many pieces of hardware and software that attempt to inject that “analog” sound; in this case the method is to give you a control to overdrive the circuit of a 12 AX7.  I have read online that if you get just the “right” 12 AX7 to swap into the box, you’ll have a wonderful preamp.  I’ve never spent any time in that direction because I don’t have that kind of time.  What I like to do with these is to use the Tube PACs for direct boxes or something even a bit more radical.  I have a 1970 Twin Reverb with JBLs that’s so clean that you have to cram it up to 6 or 7 to get it to break up.  This is ear-splitting and although I have no neighbor issues, I don’t like to play that loud any more.  So, I use the Tube Pac as an inline amplifier like the old Electro-Harmonix LPB1 except on a much higher quality level.  When you overdrive the input on my Twin it starts to do some really neat stuff.  The Tube PACs work well for direct boxes but you have to be aware of how they may color the sound if you don’t have them set properly.

Symmetrix SX202

Symmetrix SX202. I was looking for a high gain plain clean preamp for a Shure SM7B and someone on Gearslutz suggested this. It’s great. There are still plenty of these out there in the finest studios. They are solid.

I also picked up a Symmetrix SX202, a plain-Jane mixer with a gain knob and a phantom power switch on each of the two channels. These are somewhat old technology but they are still used in top studios because of their solid 60 dB of clean gain.  If you needed some high-gain clean preamps, these SX202 preamps work great and are rather inexpensive.

Allen & Heath CMC 24

Although I am using this piece as part of the mixdown system, it has great preamps and it could fill in as 16 fine preamps with an extraordinary noise floor and 30 dB of headroom!

I would be derelict if I didn’t mention the 16 channels available on the Allen and Heath CMC 24.  These channels are extremely clean, with 30 dB overhead.  They have 4 channel parametric EQ and a very extensive monitoring system (it is a recording board, after all).  So far I haven’t used the board for recording inputs yet but I think it would be fun to try.  When I have time for fun I will make it a red letter day on the calendar.

Well, that piece above covers a lot of ground.  I will probably be editing it.  I know there is pertinent material about the equipment that I haven’t covered, but this was written rather quickly so I could move onto the next page.

If there are any corrections, questions, or discussions you would like to have about this page, please just use the comment system.  I will be happy to discuss anything on this page or anything that should be on the page.




Euphonic Studio
Mount Vernon, Iowa
Serving the Cedar Rapids-Iowa City Corridor
Call 319.895.8002 for a tour or recording appointment or write
We record all types of music and your satisfaction is guaranteed!




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