RME Bayface Pro Mic Input Expansion

[tom-ka]

Hi all,

I have an RME Babyface Pro FS. I‘m looking for a mic preamp to expand mic inputs. I‘d need at least four more inputs.

I‘m currently considering either a Focusrite Clarett+ Octopre or the Audient ASP880.
Input impedance is important as I‘m using ribbon mics with 500 ohm.
The Focusrite has 6.2k ohm whereas the Audient has 2.8k ohm. So in this aspect the Focusrite would be better.

I don‘t really need any additional functions like filters and so on.

Does anyone have experience with both devices? Is there a noticeably difference in preamp quality?

Another contender would be the SSL Pure Drive Quad.

Thanks!
Tom

[Bear]

Slightly more expensive alternative is SPL P8, which is available with ADAT outputs. It has 10 kOhm input impedance on the mic inputs.

[TimJN]

I've had the ASP 880 for 8 years. It's switched on almost every day, and has worked reliably all this time. It got a very good review in SOS, which is why I bought it, and I have not been disappointed. It's well-built, and reliability--so important--is superb. It was quite an upgrade from a Behringer ADA8000, and the balanced insert sends are great to have. I'm about to use it tonight, to record acoustic guitar. It just works, day in and day out.

[ef37a]

Hi Tom and welcome. If I was looking for another mic pre I think my priority would be very low noise (especially since you use ribbons) good headroom and low distortion. I would be happy with a frequency response that was flat to a dB or so to 20kHz. I do not trust audio electronics that reaches into the MW band!
The input impedance would would be well down my list. All the comments I have read in SoS tell of a "subtle" effect? After all surely most ribbons were designed to be loaded with about 1-1.5k? That is before this fashion began!

As to the relative price/performance merits of various pres? You are perhaps too new to have read...https://www.soundonsound.com/reviews/do ... difference

Dave.

[Tomás Mulcahy]

The input impedance is a non-issue, as long as it is more than 10 times greater than the source impedance. So both pres on your list are suitable. The Audient is superb, transparent and reliable. Last time I used it on a session we also had a modern Neve 1073 preamp and it was changing the source (SM57 on guitar cab) just enough to be not as useful as the Audient. Which surprised me, because nothing was being overdriven. FWIW we have a Focusrite Platinum Octopre at work with ADAT out, in daily use, it is 22 years old and has outlasted Mackie Onyx, Behringer ADA and Digidesign DigPre all of which developed issues from heat. It is maybe a tad sharper sounding than the Audient, but I could be imagining that because it is not in the same room.

[adrian_k]

… It is maybe a tad sharper sounding than the Audient, but I could be imagining that.

We might have similar imaginations then, I thought mine was a tad ‘harder’ than my RME OctaMic.

[Tomás Mulcahy]

… It is maybe a tad sharper sounding than the Audient, but I could be imagining that.

We might have similar imaginations then, I thought mine was a tad ‘harder’ than my RME OctaMic.

Very interesting! I feel like I associate that sound with the sharp looking metal finish, so it could be cognitive bias. I haven't bothered to do a blind AB test The Digidesign DigiPre is the cleanest most transparent pre I have ever used, it's just a pity they develop PSU issues. The MIDI control is cool.

[James Perrett]

Both the Focusrite and the Audient look to be high quality preamps but one factor that I'd highlight is usability. In my experience, with an older Audient pre, they have produced a device that is designed to be used in a professional environment with controls that are easy to see in low light.

I prefer rear mounted connectors for mics and DB25s for line inputs. Focusrite seem to like a combination of front and rear mounted connectors which makes things messy when you want to use all 8 channels.

I'd also suggest looking for something used. The Audient ASP-008 has a higher input impedance while there are other MOTU and Focusrite boxes that are available for not too much money.

[ef37a]

" it's just a pity they develop PSU issues."

That ^ would put me off the whole product range! Any company that cannot produce a power supply (I assume we are talking 20W tops?) that has a lifespan of at least 30 years really does not, IMHO know its job.

I am also assuming this is not a one off? One expects people like Behringer to build to a price* but quality gear should have PSUs with at least 20% over-engineered components...bigger caps than are strictly needed and hefty transformers. You might say "SMPSUs are a different proposition" but we have had almost a century to get those right as well so come on!

*And yet I have an X802 that has not been switched off for 15 years!

Dave.

[James Perrett]

" it's just a pity they develop PSU issues."

That ^ would put me off the whole product range! Any company that cannot produce a power supply (I assume we are talking 20W tops?) that has a lifespan of at least 30 years really does not, IMHO know its job.

I am also assuming this is not a one off? One expects people like Behringer to build to a price* but quality gear should have PSUs with at least 20% over-engineered components...bigger caps than are strictly needed and hefty transformers. You might say "SMPSUs are a different proposition" but we have had almost a century to get those right as well so come on!

Just about every piece of gear that we talk about here has been built down to a price. It seems that PSU issues are now fairly common with the Audient preamps although the only PSU issue I've had with mine is the noise from the fan. One day I'll put some Traco TSR-1 modules in there instead of the linear regulators and ditch the fan. That would cost me very little but would be a big change in costs for the manufacturer if they were to fit them from new - we are talking an extra £15 or so on the BOM.

This is nothing new - even Quad were known for skimping on components with their gear.

[ef37a]

Do you mea n the ASP 880 James because I see it uses a 40W SMPSU? They could of course be feeding the outputs of that to a pair of linear regulators but if so, why didn't they arrange for a minimal voltage differential and thus low dissipation and ditch the fan?

Of course all electronic gear has to be made with costs in mind. #Not what you do it's....# !

So even Quad suffered at the hands of the bean counters? (405?) I don't recall much PSU trouble with the valve jobbies? A new GZ34 every five years or so?

Dave.

[James Perrett]

Do you mean the ASP 880 James because I see it uses a 40W SMPSU?

No, my unit is the older ASP-008 which uses a traditional linear power supply design. I seem to have become a member of the Audient Facebook group and there have been a few complaints about the reliability of the ASP880 PSU although I have no idea what percentage of units are affected. Mind you, I guess most manufacturers are affected in a similar way and you'll probably see similar tales in their online groups.

Audient have taken the same route as Focusrite and SSL and moved down to the more affordable end of the market after building their initial reputation as high end manufacturers.

So even Quad suffered at the hands of the bean counters? (405?) I don't recall much PSU trouble with the valve jobbies?

There are one or two capacitors on the 405 that fail prematurely and they under-specified the resistors on the op amp power supply which are working very close to their rated power.

[ef37a]

Ah, well there is a tiny bit of an excuse with a 50/60Hz supply as you have to allow for wobbly mains supplies. I still think they could have held the regulator dissipation to a lower value ( better regulation from a better transformer helps!) and just used convection/sink cooling.
I am perhaps a bit brainwashed by the (now deceased) technical director at Blackstar? When I asked him why he did not just put a fan in the Series one supply I got an hour long lecture on the evils of cooling fans!

Quad were then as I suspected not immune from the money men!

Dave.

[Tomás Mulcahy]

Hi Dave here is a rather long post in response to your theory "they must not know what they are doing"

yes these are all "universal" PSU. I don't know why it happens, it's almost as if one team does the main unit and some other team does the PSU which is often compromised. I have heard that "analogue" engineers are getting rare, coz all the kids want to learn digital in college? When I am recapping and trying to get decent capacitors, it can be quite a challenge going through the catalogue to find a good spec that is not over-priced. It cost €60 to recap a Sony TA FB930R, but it was worth it. Great amp, the old caps lasted 23 years. Not as good as my 1976 Quad 405 though

The DigiPre uses an off the shelf Meanwell SMPSU. I am going to recap one, to see how it goes. I hear about them dying a lot in other gear. The Mackie has the most OTT mixed SM and linear PSU I've ever seen, tightly packed into an alumimium case inside the unit. Doesn't look like much opportunity for air flow It was Mackie's universal PSU, used in many of their units and well known for failure.

The Behringer ADA is another story altogether, it's really poor. You will laugh at the regulator dissipation... Linear but with the caps right next to the hot silicon parts with a cheap transformer so the regulator is expected to dissipate a silly amount of heat IIRC 40V down to 5V. I am toying with a Behringer V Amp Pro, which sounds great (like, really great) when it works. Slightly less bad PSU, I ended up putting as high a spec cap as I could, and adding a bigger heatsink. Some other bad caps in it but the worst part is a ribbon connector handling switching between front and rear inputs. Very badly soldered.

[James Perrett]

yes these are all "universal" PSU. I don't know why it happens, it's almost as if one team does the main unit and some other team does the PSU which is often compromised.

Usually a completely different company does the PSU these days. Anything connected to the mains requires all kinds of approvals and certifications these days so it makes life much easier if a specialist company makes that parts that require certification.

Capacitors in switch mode power supplies often require a higher ripple rating than standard electrolytic caps. If you are thinking of recapping a PSU it is worth going to a proper electronics distributor like Farnell or Mouser who offer a wider choice than some of the smaller suppliers.

[Tomás Mulcahy]

Thanks James, this is not my first rodeo. I've had an account with Farnell since the nineties I find AI very useful for checking all parameters, especially dimensions- those can get overlooked. Currently searching for caps for an AKG C3000b, very hard to find the right size that is not on back-order, could take 8 months. And before you say it, yes I do use a VHF capacitance meter to measure in circuit

[ef37a]

Hi Thomas, you have confirmed what I had suspected from my limited experience in "production" that some companies do not take much care when specifying power supplies.

The late tech direc Bruce at Blackstar took as much care over this part of an amplifier as he did the rest of the circuitry.
Prior to my time there I had not understood that a 50/60* Hz supply should allow the equipment to still perform at 10% under nominal mains voltage i.e. 207V rms. You won't get the rated power, that is claimed at 230V in but regulators e.g. should not drop out.
The other edge of the sword of course is that mains can, legally be up by 10% 253V rms. This is where differentials across 78 regs start to get tricky!
These conflicting requirements sometimes meant a re working of a power transformer specc' because the pre prod sample did not come up to snuff.

Then it is just common sense to position electro-caps away from hot things but sometimes the mind set seems to be "Oh! SMPSUs are very efficient so they generate zero heat and we can stuff everything in a fag packet" Or, the ultimate cop out, "just slap a fan in there" The fact that said fan will be clogged up with fluff and bits of people in two years never enters their heads. That or the kit is placed such that the fan is 2mm from a wall.

*Over "there" could be a nightmare as the mains voltage is so variable. Reports came in of mains voltages up to 130 "down Mexico way"!

Dave.

[James Perrett]

Currently searching for caps for an AKG C3000b, very hard to find the right size that is not on back-order, could take 8 months.

Message me with the details - there might be some in SimonZ's collection of microphone parts.

[tom-ka]

Hi all, sorry for the late reply!

thanks a lot for your feedback. Really appreciate it.

I'm currently favouring the SSL Pure Drive. The switchable impedance of up to 12k ohm seems to be most suitable for my mics. The different drive modes are also a nice addition. It also got a good review here.

I guess you can't really go wrong with any of the preamps.

[tom-ka]

Hi Tom and welcome. If I was looking for another mic pre I think my priority would be very low noise (especially since you use ribbons) good headroom and low distortion. I would be happy with a frequency response that was flat to a dB or so to 20kHz. I do not trust audio electronics that reaches into the MW band!
The input impedance would would be well down my list. All the comments I have read in SoS tell of a "subtle" effect? After all surely most ribbons were designed to be loaded with about 1-1.5k? That is before this fashion began!

As to the relative price/performance merits of various pres? You are perhaps too new to have read...https://www.soundonsound.com/reviews/do ... difference

Dave.

Hi Dave! thank you! I hadn't see this article, thanks for linking it.

Tom

[twotoedsloth]

Hello,

Just dropping in to note that the Audient ASP880 has variable impedance settings.

I usually just leave mine at high, but the other two settings are also very good. To be honest, while I can hear a difference in tonality between the three impedances, but I could not tell you which one was superior.

Best regards,

Peter

[Guest]

Hello! Just to add a technical point regarding the ribbon mics with a 500 Ω ribbon, the usual recommendation is that the preamp input impedance should be at least 5–10 times higher than the mic’s output impedance to avoid damping the transformer and losing low-end or output level.

In that sense, both 2.8 kΩ and 6.2 kΩ are technically workable, but 6.2 kΩ gives a more comfortable margin.

That said, impedance is only one part of the story. With ribbons, clean gain and low noise are often more important than small impedance differences.

It may be worth comparing the EIN specs and maximum gain of each unit, especially if you are recording quieter sources.