Mix Bus Compressor from scratch

[slipperyflax]

It's been a pleasure to follow! Great work!

 

[rock soderstrom]

The project is now finished and ready to pack for shipment, these are the final schematics.

Thanks for the information, inspiration and really good entertainment!

 

[Newmarket]

In the late 60's I played with band at a gig very near the big transmitter on the hill just south of London. When we turned on our Selmer amps we got radio and TV stations loud and clear. 68k grid stoppers could not overcome it!
best
DaveP

Crystal Palace ?
If not it should also be mentioned in the link posted https://en.wikipedia.org/wiki/Crystal_Palace_transmitting_station
And stuff there I'd nearly forgotten about. Nicam sound and the 405/625 switches on TVs

 

[DaveP]

Crystal Palace ?

That was the one.
DaveP

 

[thomasdf]

Bravo Dave !! What's your next project ?
Reminds me I went on tour and never got to the end of your hifi transistor amp ! I'll check it out

Keep these builds coming, they are really enlightening as well as eye candies

 

[IBart]

I thought I pop a reply in here of how the buss compressor is sounding.
Daves builds are always so fantastic. They are top notch.

And I’ve worked on tons of pieces of gear in LA, Nashville and London and at my home studio the audio boxes he sends me are sonically and build quality excellent, they totally stack up against the big audio names for sure.

Sound wise
Overall it adds a bit of saturation / glue and roundness to a mix

It sonically has a mid foward tone to it, its only subtle but that what its doing to a mix

It adds a small amount of width to a mix, when level matched.

It shaves off the transient 5% (a musical amount not too much)

It adds a bit of sheen as well and rolls of a teeny bit of highs.

Its rich sounding , harmonically speaking, I believe Dave said this will be similar to another box he has made me ( sonically ) as it uses chokes or something like this. I have no idea what that is, other than m y dad had this 60’s pickup when I was a young boy in the 80’s and it used to have a choke on it, and on a cold morning it would need more choke than on a hotter day

The compression is excellent and very useful for mix buss, obviously I’m using slow attack and currently playing with the release times for what I think I might be a set and leave setting, but the slower release times seems to be winning.
But it has a SSL-esq tightness when on the quicker release settings.

I;m going to just try it on drums today for fun to see how tight I can make them with this compressor.

I have a cheap but passive switcher unit , which arrived last year , its for mix buss boxes that I can switch in and out, its only four channels but highly useful. So I can litrally switch in the new mix buss compressor and match gains very easily now

Years ago I would have to patch in a new unit then bounce it in and then bounce out and see which one I’d prefer.

So yes , the mix buss compressor that Dave has built will be living permanently on the mix buss, not using that much compression but its the sonic imprint I wanted and I am very pleased with.

Yes Dave and I have been working together for 8 years and I use all his boxes ( pretty much ) every week

I’ve had a good start to the year with 5 songs on national radio this year, four on radio 2 and 1 on Jazz FM ( which I didnt record but it was recorded in LA by Larry Crane who is really rather good at his job and allot more successful than me !! )

I am currently mixing some live gigs for Allman Brown. Also writing with a west end show singer Marisha Wallace.
Doing two tracks for an EP with a new artist Gabby Martin. And currently finishing off Ladybryds album.
In September I’m about to record Judi Jacksons album, also finishing a new artist record called Grace Humphires , she flys over from Texas. All the recordings will be vocals through 3 of Daves boxes ( the RCA comp, the UE 100 and the mic pre the 241-76 ) and now the mixes also through his new mix buss compressor !!!

I LOVE THESE UNIQUE UNITS , they sound so good.
And also they are unique to me, which I also like !


Ian
www.ianbarter.com

 

[scott2000]

I have a cheap but passive switcher unit , which arrived last year , its for mix buss boxes that I can switch in and out, its only four channels but highly useful. So I can litrally switch in the new mix buss compressor and match gains very easily now

You know you can't just tease everyone..lol
Does it have attenuators built in as well?
Is there an active gain somewhere in your chain or do you use makeup gain on the units themselves? Some units don't provide output gains so I get curious how others compensate before AD conversion if say a compressor lowers the level...
got pics?

 

[IBart]

You know you can't just tease everyone..lol
Does it have attenuators built in as well?
Is there an active gain somewhere in your chain or do you use makeup gain on the units themselves? Some units don't provide output gains so I get curious how others compensate before AD conversion if say a compressor lowers the level...
got pics?

Here are some pictures, I think Dave took better ones a few posts back.

Yea I can change the gain of most mix buss boxes I use, but the passive switcher is soooo useful for seeing what you want

This is the switcher unit
https://ka-electronics.com/shop/index.php?route=product/product&product_id=78

This mix buss compressor, its exactly what I wanted, imparting lovely analogue / richness to my mixes , thank you Dave

Ian

 

[protools]

Here are some pictures, I think Dave took better ones a few posts back.

Yea I can change the gain of most mix buss boxes I use, but the passive switcher is soooo useful for seeing what you want

This is the switcher unit
https://ka-electronics.com/shop/index.php?route=product/product&product_id=78

This mix buss compressor, its exactly what I wanted, imparting lovely analogue / richness to my mixes , thank you Dave

Ian

Realy nice custom gears...and fine ATC monitors! Love it!

www.kmsmastering.com

 

[[email protected]]

Realy nice custom gears...and fine ATC monitors! Love it!

www.kmsmastering.com

Your studio looks great !

And those soffit mounted must sound great ! Nice touch the wall being sea through

 

[protools]

Your studio looks great !

And those soffit mounted must sound great ! Nice touch the wall being sea through

Yes, soffit mounted ATC is another world...awesome!

 

[Adolph Ernst]

The project is now finished and ready to pack for shipment, these are the final schematics.

C1 and R1 form another time constant for the CV. I don't know if this was mentioned earlier but it's likely needed to make any thumps low frequency enough to make them inaudible. If the user believes the attack is 1 ms (whatever that means), then it is 1ms.

 

[DaveP]

Someone who has been following the circuit closely has informed me of some typos, so I have posted the corrected schematics below.

The EF83 now has the Va and Vg2 the right way around!

The side channel no longer has two C13's and C14 is reduced to 2.2uF instead of 22uF. The input diodes were incorrectly labelled as IN4048 instead of the more normal IN4148.
Thanks for noticing
best
DaveP

 

[Johnny1234]

Hi Dave hope is good.
Only other thing I can see with the final schemaic is it does not show the output to the side chain circuit. I hate to assume "because it am always an ***" is that it is feed from the plate anode of the E83F. Is that correct. Also what is the voltage rating of the 6.8nf caps in the side chain circuit?
Again many many thanks
John

 

[DaveP]

Hi John,
Several pages back I made the switch to Feed Forward, so there is no output to the side chain from the output stage
The side chain is fed from the input sockets direct. I labelled it left and right inputs, but I think I could have made it clearer if I had said pin2.
The 6.8nf caps were Farnell part number 116 6870 6800pF 220V
best
DaveP

 

[Johnny1234]

I could not have done this with out all the fantastic help from DaveP.
He is the ultimate diy master. I hate the knobs they go next week.
Thanks a million Dave.

 

[[email protected]]

I could not have done this with out all the fantastic help from DaveP.
He is the ultimate diy master. I hate the knobs they go next week.
Thanks a million Dave.

Fantastic !

Howsit sounding ?

 

[Johnny1234]

Ok, I probably started planning this project back in February. Most of my questions were PMed to Dave so as not to clutter up this thread. Well two nights ago I got my first signals, but no control voltage. Found and corrected feedback resistor on side chain. Now wallah, It sounds incredible to me. I usually like scientific numbers and not it sounds like so so so...warm, fat, et al. I am going to be buttoning up some loose ends in the coming days and will post more pictures and a frequency response report. I've been in this project from the beginning and now it is more than worth the time, money and effort. I could never have done it with out the generous help from Dave. She was a slow build, but you know when your not working you have the time and not the money, and when your working you have the money but not so much time. I have to highly recommend building this compressor, and a very special thanks and God bless to Dave.

 

[DaveP]

John never gave up, he persisted and reaped the reward, well done mate!
best
DaveP

 

[IBart]

Ok, I probably started planning this project back in February. Most of my questions were PMed to Dave so as not to clutter up this thread. Well two nights ago I got my first signals, but no control voltage. Found and corrected feedback resistor on side chain. Now wallah, It sounds incredible to me. I usually like scientific numbers and not it sounds like so so so...warm, fat, et al. I am going to be buttoning up some loose ends in the coming days and will post more pictures and a frequency response report. I've been in this project from the beginning and now it is more than worth the time, money and effort. I could never have done it with out the generous help from Dave. She was a slow build, but you know when your not working you have the time and not the money, and when your working you have the money but not so much time. I have to highly recommend building this compressor, and a very special thanks and God bless to Dave.

it does sound great !

a great tone