500/51X Series SLQ51X SSL styled 4000 EQ / Filter

Kevin · Oct 4, 2020

Hi Friends
Since the last weeks i'm designing this loved SSL Styled EQ for 500/51X series
i used the shematic of the 4000 EQ with 1246 In- and 1646 Outputs.
In my Version I added switchable Low Cut and High Cut Filters
Biggest Problem as always small Potentiometers. but i found cool working pots
Its running on +16V/-16V in the VPR or 51X Rack

UPDATE 2.11.2020:
I finished my second prototype boards and and got a nice frontpanel from Frank, final version will be black powder coated so i can offer kits in November, so christmas is saved for DIY. Also the Knob Caps for High Frequency will be RED. At same time I working on a white Market Thread.

For All who love Measurments

Here are some listening samles

All Build Info(BOM,Schematic/Overlay/Stepbuild) will be avaivable under this link
https://docdro.id/SwVY5uM
White Market Thread
https://groupdiy.com/index.php?topic=76303.0

NOTE: For all who assemble the EQ on theirself this not a beginner project, i would say it's a bit more complicated than an VP312 but not that difficult than a BT50. there is also a lot calibration after the building. But if you did this before you should be able to get this EQ together

TillM · Oct 4, 2020

Hi Kevin!
sounds good !
It will depend on the price, but I’m really looking forward for it.

Ricardus · Oct 4, 2020

I am definitely interested. I will have to see how funds work out because covid has definitely hurt my income these last 5 months.

boji · Oct 4, 2020

I'd likely be in for a pair. Thank you!

uptownsquash · Oct 4, 2020

i would be interested for 2-4 of these price dependent

john12ax7 · Oct 4, 2020

Were you able to get small enough knobs? I did a version of the 4k but found the front panel a bit too cramped with the smallest sized knobs that were available, think the commercial version is a custom mold. The PCB layout gets rather tight too with through hole. Just some things to keep in mind.

It's a great project, and a great mixing EQ.

Kevin · Oct 4, 2020

Yes the commercial one has also just 11mm knobs,
i use sifam 11mm knobs for this project. but i have two pcbs top on top and place parts between these two pcbs. than it gets a bit easier to place that many parts.

At the moment i think the full kit including everything will be in the range around 170-230 Euro. But i need to calculate again soon.
I will have the final price for the full kit in a about two weeks when i order my my test frontpanel.

Winetree · Oct 4, 2020

i would be interested in 2-4 of the kits.

BerndVP · Oct 5, 2020

Interested in 2-4

JMan · Oct 5, 2020

Also interested, probably in for a pair as well

12afael · Oct 6, 2020

I´m doing a similar project, any tips where to get these pots? I got them all but in different shafts configurations.

Kevin · Oct 8, 2020

yeah i use alps and ttpots. i got all from different suppliers. some from german distributors and some from mouser. too much complicated to get them all from one place. sadly. will get my prototype together next week, so there will be more pictures then.

rob_gould · Oct 8, 2020

Interested in a kit or two depending on price

CiaoPatsy · Oct 9, 2020

Lord yes!!! In for a pair.

MountCyanide · Oct 9, 2020

10 Knobs. NUTS! Good job.

Malcho · Oct 11, 2020

+2 kits and panels

fragletrollet · Oct 13, 2020

How are the controls for the hp/lp implemented? I see the holes in the middle of the panel, but are those for pots or toggle switches? Is the cutoff variably controlled with a pot, or are toggle switches switching in a hp/lp with pre-set cut-off frequency? If using pots, where are the graphics for the cutoff frequencies?

I do understand if they are toggled because of limited frontpanel real-estate...

Kevin · Oct 14, 2020

Yes the hp/lp are just toggle Switches, but with indicator LED, i use fixed frequencies for that. 80Hz and 12kHz Cutoff. its a 3 Staged circuit like you already know from the 9k/4k by Bruno Preamp. It's a 3rd order Sallen Key Filter. In fact you still have shelf filters for low and high and reduce with them frequency wise the cut or boost. And in fact 10 pots are the maximum you can squeeze on a 500 panel. if you put the 11th Pot there you can't put maybe just one other toggle switche there.

Kevin · Oct 20, 2020

updated all infos in first post

BerndVP · Oct 21, 2020

Looks good!
Maybe going for a more SSL 4000 color look ?

And HF knobs maybe red too ? Like the real thing ?

500/51X Series SLQ51X SSL styled 4000 EQ / Filter

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