500 vs Eurorack?

AKA, what Euro compressor should I buy? Its your rack, but I would advise: none. This comes up a lot but I haven’t written a blog post yet. Usually it’s when someone is looking for “mastering” gear inside their case. I usually respond. Eurorack is objectively terrible for mastering. What?!? Aren’t I supposed to be telling you to buy all kinds of Eurroack? Not in this case. I design, build, and sell Eurorack Modules, I also build, and occasionally sell 500 series modules. I’ve been recording with them for years and I’ll never go back. There are many reasons why, but I’ll go over the main ones: Power and Power Connectors, Headroom, Audio Connections, Parts, and Transformers.

Power and Power Connector

When Deiter made Eurorack, modules were analog and Power was linear. A clean linear +/- 12V supply was more than enough to power a case of analog modules which each use only 10s of mA. As the format grew, digital modules popped up which linear supplies were unable to power, so people made switching supplies of various quality. Some are better than others, but I have yet to find one that is totally clean. Due to noise and cross-talk, most switching Eurorack supplies are not comparable to a pro audio supply, which are usually linear. Eurorack power is delivered via a bus board, which is good, sometimes via a ribbon – not so good, and IDE cables deliver power to and from your modules. In a clean linear system, this is fine, but again, with switching supplies, your system will be about as quiet as a 90s PC – not ideal for pro audio.

500 series systems comes from classic API consoles and was standardizes as VPR in 2006. It delivers +/-16V via card connectors.

The edge connector is part of the main PCB, it is very strong and lugs into a very sturdy card connector. Variations on this system have been used in professional studio mixers since forever. They are quiet.  The cool thing (to me) about 500 Series edge connectors is that the designer chooses what connectors they want on the module. For instance, the module pictured above, which sounds just like my 5176 Compressors, doesn’t have connectors for phantom power, as it’s a compressor and doesn’t need it.

Headroom and Audio Connections

Eurorack uses unbalances 1/8 cables. The average dbU a Eurorack user should expect is roughly 13.2dBu. This is an excellent and thorough write up on the subject: https://northcoastsynthesis.com/news/all-about-levels/. 500 series use balanced I/O which cuts down on noise and withstands long cable runs. The headroom of a 500 series system/outboard gear/mixing desk is +4dbU. This may seem like a big difference, but it isn’t really in practice. I always plug my Euro gear directly into 500 series, sometimes by attenuation or with a VCA, and sometimes with a Euro to Line output module. Of course gain staging with a 500 series module is where a lot of the fun is – cranking up the gain on a preamp for gentle harmonic distortion and then trimming the output – I’ll get to that at the end.

Parts, and Transformers

These is SUPER important. 500 Series modules and pro audio gear use beautiful beefy audio transformers, and they sound absolutely fantastic.Why can’t we use these in Eurorack? Well these transformers weigh between 1 and three pounds each. That’s a lot of copper, and they DO make a difference. A Eurorack module usually weighs less than a pound all-in. Two pounds of transformers in addition to all the other stuff going on on a euro PCB would bend that poor aluminum panel in half and warp your rails if we tries (that’s exaggeration, but it’s not not true). 500 series module are supported by the rack along the bottom and top and often times have their own “chassis” to protect the module. That’s me harping onto transformers… on to DOAs.

A DOA is a Discreet Op Amp. Before we had TL074 ICs we used these, and they still sound great.

 

DOAs come in many flavors, but the main thing is: they sound great – just like classic gear, and they take forever to build. You often need to match obscure transistors and resistors, and hunt down rare parts. For us small makers, in order to make your eurorack modules, we need to have a pick and place robot place and solder Op Amp IC chips onto PCBs, we simply don’t have time to build these for you (and they would be huge – I would need 16 of the above to make a stereo matrix mixer). None of us are getting rich of euro, so we couldn’t afford to charge you what it would cost to use these instead of Op Amp ICs. Speaking of pick and place…

Sometimes it doesn’t matter if a resistor is NOS thru-hole or SMD, but caps in the audio path DO matter. Those red capacitors in the image above are called WIMAs and they are pro-audio standard. Your average maker will have to make do with a pick-and place polyester Cap (if they bother). Most makers can’t afford to spend time hand soldering a bunch of WIMAs on a per unity basis, so this is another area where a more expensive 500 series module is going to have better parts.

My favorite 500 Series Modules – and why

All of my modules are for recording on the way-in. I like to commit to sounds, and I usually EQ in the box, so these modules are going to be mostly pre amps and colorizers. I’m also going to include two pro audio units I use basically all the time.

The basic signal chain is a pair of Fet Compressors I built (1176 clones) into a pair of “Audio Bacons” I built the “audio bacons” thinking they were snake oil, but I saw that they sold, so I built them anyway. Not snake oil – not at all. I’m constantly stopping myself from building 8 more.

Other Pre Amps (all stereo pair):

Lolas – Go to clean or overdriven. Love it on Rhodes.

Bronzes – Great for Bass – percussion

APP Studio MR1 – Germanium pre-a,ps that can really transform a bass signal into something wild.

Compressors – CP5176 – like an 1176 with more options. If for some reason the Fet comps aren’t doing it, or i want some harmonic distortion, these will do it. The link is to the product, mine are in my rack.

Audio Bacons

But what about live?

Live your sound person is almost certainly using a digital console with dynamics they have dialed into their room. They will know it better.

But there isn’t really a sound guy? Then is it really worth it for a backyard or a basement gig with whatever borrowed speakers? I get it. I used to use a Yamaha Pro Mix 1 for this – great EQ and compression and under $100 with recall! You can even use it as a midi controller.

Conclusion

Keep in mind I don’t have any fancy recording credits (but neither does your average studio youtuber (shhh)). I do record though, and even my post DJ ears can tell the difference – it’s huge!