DIY channel strip - 1173 + eq + optional compressor

[VeinsDIYer]

Hello everybody
For our next album, we need to upgrade the studio gear, so I am thinking about DIY'ing 8-12 preamps to record drums. I have experience in components sourcing, PCB layout, and also have good soldering equipment.

I was pondering for 1173 clones to fit in a 500 series format. I was thinking that, since a good portion of the budget is for input/output transformers, adding EQ and compressor circuits on a line-level path between the PRE and the output would actually not impact the price much.

Do you have experience in creating custom channel strips with classic designs, such as 1173 + Caltec EQ + 1176/78 or even 33609?
Would the lack of an input/output transformer (if present in the original design) of the EQ and compression affect the desired tonal impact of the stage?

Is it a proper idea in the first place?

Thank you very much

 

[ruffrecords]

A very hard question answer since we know nothing of your existing set up.

And I have to ask, do you really need 8 to 12 preamps just to record drums?

Cheers

Ian

 

[TwentyTrees]

One immediate issue with any channel strip in 500 series is space - it's a very confined format. In particular, the 1073 uses chunky transformers and a large gain switch which doesn't leave a lot of space in the module for anything else. Have a look at the AML ez1073pre module, and you'll see what I mean.

You'll also find you're limited in terms of controls for EQ and compression, just in terms of front panel space. For example, a 1073 (with output pad) > Calrec PQ1549 EQ > 1176 would be some 15 rotary switches and pots, and 10+ toggle switches. So looking for slim-line control options (eg 3-band fixed frequency EQ, one-knob compressor) might be required.

That said, it's not impossible, and if you can lay out SMD then that will certainly make things a lot easier to roll your own combination. Iron Age Audioworks have managed this with their 622 channel strip, for example.

 

[rogs]

I have used a dbx286s channel strip for a while now, and its pretty good. The EQ ptions are a bit limited though.

I came across this channel strip online and for £120 I thought it might be worth a look.... I wasn't expecting too much though!
In fact it's not bad at all! ....
Balanced I/O - pretty good mic/line preamp with phantom power and adjustable low cut - gate/expander - compressor with external side chain (THAT 2181 VCA ) de-esser - and a 4 band parametric EQ.
Internal PSU, and 1U rack mount.

OK I'm not in the business of recording international stars so I don't need really top priced kit, but this was a lot better than I though it would be.
And I couldn't buy all the DIY parts for that money!

 

[beatnik]

Although 500 series might look cool at a first glance, it will cost you more money, might take more time to build, and I guess it's more things that could need maintenance over the years

It sounds like you are after a more defined system, more like a console sidecar in a way. In that case I don't really see any advantage using the 500 series format.

The 1073 preamp is definitely a good choice for drums. If you can afford the cost of the extra inductors and switches you could make the full preamp+eq module. It's next to impossible to get a bad drum sound out of this

For compression you should consider the SSL style compressor which works great on drums, or also the DBX160 VU.
These can be built quite affordably without signal transformers.
I am not aware of a 1176 without output transformer but I guess the output stage could be redesigned for transformerless operation.

 

[VeinsDIYer]

Thanks a lot for the answers!

A very hard question answer since we know nothing of your existing set up.

And I have to ask, do you really need 8 to 12 preamps just to record drums?

Cheers

Ian

8 would be enough, but if I can manage to keep the price down, why not.

One immediate issue with any channel strip in 500 series is space - it's a very confined format. In particular, the 1073 uses chunky transformers and a large gain switch which doesn't leave a lot of space in the module for anything else. Have a look at the AML ez1073pre module, and you'll see what I mean.

You'll also find you're limited in terms of controls for EQ and compression, just in terms of front panel space. For example, a 1073 (with output pad) > Calrec PQ1549 EQ > 1176 would be some 15 rotary switches and pots, and 10+ toggle switches. So looking for slim-line control options (eg 3-band fixed frequency EQ, one-knob compressor) might be required.

That said, it's not impossible, and if you can lay out SMD then that will certainly make things a lot easier to roll your own combination. Iron Age Audioworks have managed this with their 622 channel strip, for example.

I thought about the 500 series because of modularity (if I want to change the eq or comp section, I can make another board), but the most affordable solution would actually be to implement the strip in a 1U 19'' rack unit. Also, I am digging the idea of in/out transformer in the signal path. My question was about the insert of the eq and comp stage before the output transformer of the preamp. This way the actual price of the eq and compressor would be cut down as their trafo will be already included. Of course might be necessary a buffer to match the impedences of the different stages.

I was just curious if somebody had already tried it!

Thanks anyways

 

[TwentyTrees]

Ah - I'd understood that you wanted an entire channel strip in a single 500 series module. If you're looking at, eg, one rack of preamps, one rack of EQs, one rack of compressors, then the world's your oyster - even more so if you're open to other formats.

The 1073 has an insert point for the EQ section, before the output amp. Many 500 series versions, DIY and otherwise, implement this as an unbalanced insert. I'd be tempted to look at this for the EQ + comp rather than between the output amp and the output transformer, as if memory serves the amp is designed to work specifically with that transformer (impedances, gapped for DC, etc).

 

[beatnik]

I'm not aware a complete DIY ready option for a channel strip exists. If you had to puzzle together different pcbs, fitting a whole channel strip in a 1U chassis might be a bit of a challenge, unless you are good at pcb design and can make your own boards.

Separate rack enclosures is actually not very cost and time effective, best to reduce metalwork to a minimum.

You could use frontpanels.de rack enclosure with mounting rails which is modular so you could start with a 3U enclosure and make the Neve preamps, then join another enclosure for the EQs and another for dynamics.

Basically this is the same format as having 3x 500 series enclosures but it should save quite a bit of money compared to off the shelf commercial enclosures and you have the advantage to be able to internally connect the sections whichever way you prefer.

The most cost effective option would be a 9U/10U enclosure and just make a single module for the entire channel strip. making a single front panel instead of splitting each channel strip into three separate front panels will save you quite some money.

You will have to start with a bigger investment though, whereas the modular enclosure allows to expand it as funds become available.