Reel to Reel Tape saturation

ChristopherTheo

New member
Hey guys I own a Revox B77.

Putting the audio from my daw and recording it into the Reel isn't a problem.

I want to get the best results when converting it back to the digital realm, I was looking at DAC Converters.

I currently use a focusrite 6i6 to run it in and out of the tape, but I just wanted advice on if there is a better solution to have the best quality going back into the digital.

I was looking at this product, do you think this would be a good solution?

Korg DS-DAC-10R - Thomann UK

Thank you
 
DACs go from digital to analog, not from analog to digital.

I think your interface is the right tool for this job.

+1.
Excellent machine Chris, much improved on the A77 (which was PDGood!) . However, although the B77 has a very good specification in terms of S/N ratio and distortion (for OR) the figures are SO much worse than any converter I am aware of that there really is little point in looking for better than the 6i6. In fact you could run at 16 bits and save ram space!

In fact, you could use the Beri, UCA 202 with some input trim pots and leave it permanently setup to the B77 thus freeing the 6i6 for other duties, or just to avoid 'plugging/re-plugging'?

Dave.
 
Thank you for the responses. I have used the 6i6 and although the signal coming back isn't bad,

I feel there must be a way of having stronger and more pristine signals going both ways?
 
Thank you for the responses. I have used the 6i6 and although the signal coming back isn't bad,

I feel there must be a way of having stronger and more pristine signals going both ways?

I don't understand? The level going FROM the 6i6 (which is?) should be excellent if the source is same. The signal BACK from the B77 will of course only be as good 'as tape gets' but I would say a well setup B77 is very close to a mastering grade machine.

Do you understand 'gain staging' and levels? Are you having a problem getting enough signal into the tape machine? I shall look up the I/O speccs of the two devices and get back to you.

Dave.
 
" Aim beck!"

Hmm, yes you might have some level interchange issues. the 6i6 puts out +16dB, 6.3V for 0dBFS whereas the LEAST sensitive input on the B77, AUX, needs just 40mV* for (I assume) +6vu. You therefore stand a good chance of overloading the B77's front end. You could of course keep digital recording levels low but that flies in the face of 'Good Practice' which is to have an essentially 'unity gain' signal path both ways.

The B77 can put out +6dBu (at +6vu) and the F'rite can handle up to +22dBu so no problem there. You might of course not have a problem but had I that setup I would build a small jack box containing two trim pots (10k log) and set the system up for a good level from the 6i6 and then trim down to a level the deck can handle comfortably. Essentially if you SEND a signal at say -18dBFS TOO tape you want a signal back that produces -18dBu in the DAW.

* Of course this is slightly poor design and a remnant of the DIN signal system. Having a lot, ~32dB, of gain in the front end then attenuating it increases noise but back then, electronics was SO much quieter than tape, nobody cared muchly.

Dave.
 
Hey guys I own a Revox B77.

Putting the audio from my daw and recording it into the Reel isn't a problem.

I want to get the best results when converting it back to the digital realm, I was looking at DAC Converters.

I currently use a focusrite 6i6 to run it in and out of the tape, but I just wanted advice on if there is a better solution to have the best quality going back into the digital.

I was looking at this product, do you think this would be a good solution?



Thank you

Check out RME for great inexpensive AD DA often found second hand. Many of their bits are way above Focusrite quality and not much more in cost.

You also get their excellent metering software with some of the products which would be ideal for making sure you are gain structuring right in and out of the tape :)
 
LOVE! RME kit! But, taking the noise, distortion, wow, flutter, scrape flutter sidebands and HF squash of even the excellent B77 into account I doubt you could hear a difference between Prism converters and a Behringer UCA 202!

IMHO the 6i6 F'rite will be MORE than good enough.

Dave.
 
As an owner of the UCA222 I wouldn't recommend anything from that family for anything too serious (it shares the same PCB as the UCA202). There are some idle tones happening in the ADC which would almost certainly be audible on high dynamic range material. It is fine for cassette or loud vinyl but the B77 is capable of more dynamic range.

In the original Hifi For Pleasure magazine review of the B77 they complained about the lack of headroom compared to expensive professional recorders but, in practice, I've not found it a problem. The input amplifiers seem to have plenty of headroom - even from the +4dBu outputs of my mixing desk. The input level controls are usually set between 4 and 5. Mind you, I don't use elevated levels on tape.
 
Hi James.
My comparison of the Prism and the 202 was rather off hand and of the "Sublime to the ridiculous" stamp!

Mind you! The spectra of my 202 shows no great spiky artefacts? Not pristine I grant you but I believe any noise from the 202 would be well below tape noise from the B77?

Noise specs of the latter give -67dB for 1/2 track at 7.5ips, can we allow -70dB at 15ips? Very good of course but they are A weighted figures. My tests of the 202 gave -78dBFS with the gain at 100% in Windows. Back that off to a more reasonable 10% and the noise improves to -84dBFS*. UNweighted. Can we say at least -80dB and around -90dB A weighted respectively?

I don't have a B77 (slurp!) but I would bet a UCA202 would make 'transparent' copies of such a machine. However, one problem would be the lack of input headroom of the converter. Max in is about 1V rms and I think the B77 can easily exceed that? A pot in a tin is easy enough to arrange.

*If I can find a mo' I shall see if I can find an optimum gain setting for the Berry box. BTW my current device is actually the UFO202 with the RIAA/line switch but as you say, they all use the same "engine"!

Dave.
 

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Stronger and more pristine? Is your existing setup failing you in some way? Sounds like you are unhappy with it? All the interfaces I have tried are worse on the mic input than the line level ones, so I'm just surprised, that's all?
 
The B77 has output level controls on the back so no problem matching the output to a device like the UCA. The noise from mine looks different - I'll see if I can grab a screenshot later.
 
The B77 has output level controls on the back so no problem matching the output to a device like the UCA. The noise from mine looks different - I'll see if I can grab a screenshot later.

Ah! Now James, the early 16 bit converters that you get in bog end mixers DID put out some horrendous spikes! Start at 1kHz and go up every 1000.
These spikes can be 10 or more dB above the noise floor (about -80dBFS) .

The UCA 202s never suffered from this problem IME but my Mk1 A&H zed10 does! (will do a shot later) A&H peeps told me it is inherent in the converters and nothing can be done about it. They, like most mnfctrs have gone 24bit. I recently bought a Soundcraft 8FX for son and that is super clean.

If you want to know my MO for recording the 202 noise? Samplitude SE8* and just ran for 30 seconds with the inputs O/C (where the 50Hz blip comes from shouldn't wonder! I set the recording level in Win 7 Sounds to 100% and 10%.

*Yes! I DO have Prox 3 but the meters in SE8 can be set down to -90dBFS, a feature they seem to have dropped in later incarnations?

Dave.
 
Hopefully the picture below shows an instantaneous analysis for my UCA222 - there's an obvious tone just below 1kHz in that picture although the actual frequency varies over time.

UCA222IdleTone.png

And for comparison here's a section of blank tape through my studio convertors with the same settings on the spectrum analyser (albeit sampled at 96kHz).

TapeNoise.png
 
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See the spectrum of my 202 in Reaper RTA James? (took me a time to find it. Don't use/like Reaper!)

No spike at or near 1kHz but in any case my point is that if you set the gain of the device low enough in Windows the programme noise, especially tape, will mask any artefacts?

I agree however, the 202 is borderline good enough for the job. I have to say...You can see from the other plot how tape EQ (NAB?) screws the noise spectrum especially at LF!

Will do a shot of my ZED10 mixer later. Brekky time!

Dave.
 

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a -99dB spike at 1KHz would be so far into the noise floor of the rest of your system, it wouldn't worry me at all.

It's a bit more complicated and insidious than that Rob. See attached the spectrum of my zed10 USB (gen 1 16bit. All chans 0, main out at '0' 2o'clock) There is a spike at a tad under 700Hz and well below "100dB"? Not in practice. The actual noise floor about -85dB and so that spike is clearly audible unless masked by other noise. Even for tape it might be intrusive.

The "fix" from A&H is to set the PC recording level way down to 5% and hit the converter harder. That works ok for noisy band jobs but not acoustic guitar in a Npton leafy suburb at 2am!

Dave.
 

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Normalized the noise because my hearing threshold is WAY below all of yous chaps! Think you will agree, you don't need much of that to be annoyed!

Dave.
 

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a -99dB spike at 1KHz would be so far into the noise floor of the rest of your system, it wouldn't worry me at all.

Remember that the second plot in my post is the actual noise from a silent section of reel to reel tape (30ips with IEC eq). If I'd used the Dolby A decoder it would have been even lower. So that spike is well above the noise floor from a good analogue tape and certainly audible on quiet material.

The point that I'm trying to make is that a Revox is a decent machine that deserves to be partnered with a reasonably good a/d convertor.
 
Quick question Dave - how do you reduce the gain of your 202? As far as I can see the input level is fixed so I ended up making an attenuator cable for mine.
 
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