Looking into building a compressor

[DeadSpeaker]

This might be a little ambitious. I do a lot of recording and mixing with my Alesis mixer and my computer, and I want to run the mix master out into a compressor for mastering purposes. I've been looking at the SSL clone seen here: http://www.gyraf.dk/

I'm hoping that it will tighten up my final mix and give it a nice analogue glow. The plan was to run the 2 track out of my mixer into the compressor and then back into the mixer via the 2 track in.

The problem is that the mixer 2 tack outputs and inputs are unbalanced whereas the compressor is balanced.

I'd very much appreciate advice and opinions. Thanks.

[TheSeekerr]

I had a look at the circuit for the SSL clone on the DIY pages.....it's a perfectly good compressor circuit, but I don't think you're going to get much of an "analogue" glow out of it....whatever that's supposed to mean.

As for the inputs and outputs......the first opamp in the signal chain is converting the signals back to unbalanced, and so that whole section can be omitted if you're giving it an unbalanced in. I think the pair of opamps on the output is only functioning to convert back to balanced again, but I haven't looked too closely at that, so I wouldn't go taking my word for it.

Given that you're looking for an "analogue" sound, I think maybe you should look at the 1176 clone instead.....I think the discrete FET's are more likely to give you what you're after than the THAT IC's in the SSL clone.

[DeadSpeaker]

Thanks for the reply. I guess what I was trying to say earlier was that I am trying to make my mixes sound less digital by using some old school hardware. The 1176 looks very appealing except that the Lundahl LL5402 output transformer is hard to find/pricey.

From looking at the schematic, can you tell if the 1176 can be converted to unbalanced? Would I be better off building a sort of dual DI unit for inputs? XLR out is ok because I can just use the regular inputs on my mixer.

Thanks for the help.

[Keith Taylor]

The Picocompressor forum at http://www.picocompressorforum.com/f...wforum.php?f=1 could be of interest to you. Have a look in the "Build" forum. There are some very capable contributors on this forum and you are sure to come across plenty of ideas on interfacing balanced and unbalanced circuitry.
Keith

[TheSeekerr]

Again, it looks like the NE5532 on the input is doing balanced to unbalanced conversion......I'm 99% sure that stage could be omitted and the signal applied at the input of the 10K pot (R5). As far as the output goes, I'm really not sure....I -think-, and I'd take a close look at the schematic before taking my word for this, that pin 6 on the output transformer is at 0V, and so perhaps an unbalanced signal could be taken from a DC blocking capacitor at the point shown as transformer pin 1.....an amplifier stage there would probably be necessary to add perhaps 6dB of gain.

http://www.gyraf.dk/gy_pd/1176/1176sch.gif

Anybody care to check if I'm right?

[DeadSpeaker]

I see what you are talking about on the input. I didn't realize this was mono until just now. That is not a problem because I can run one channel at a time and combine them again in my DAW. I'm not sure if that is good practice. The manual does say that the compressor has been used in mastering studios, so that might be how they did it before DAWs came about.

Thanks again.

[TheSeekerr]

I have a feeling the pre-DAW solution was just to build / buy two!

[Eva]

Consider compressing each element of the mix separately rather than the whole mix at a time.

The purpose of compression is to get the wild dynamics from microphones and pick-ups under control without the harshness of clipping.

[DeadSpeaker]

Originally posted by TheSeekerr
I have a feeling the pre-DAW solution was just to build / buy two!

After looking over the manual, I believe you are right.

Originally posted by Eva
Consider compressing each element of the mix separately rather than the whole mix at a time.

The purpose of compression is to get the wild dynamics from microphones and pick-ups under control without the harshness of clipping.

Right. I compress things in Sonar and do all sorts of stuff to get the mix sounding nice. I like to add a final digital compressor on the master bus. That sounds nice to me. My reason on building a compressor is to give my final mix something special.

[TheSeekerr]

Originally posted by DeadSpeaker

Right. I compress things in Sonar and do all sorts of stuff to get the mix sounding nice. I like to add a final digital compressor on the master bus. That sounds nice to me. My reason on building a compressor is to give my final mix something special.

I don't generally do recording, most of my work is in live mixing, but I work the same way, generally, if I'm using a digital desk - use the onboard digital compression for the channels that need it, then integrate the mix and add some character with an outboard (DBX) compressor. So I understand your goal.