Gyraf compressor parts.

[Thirteen]

I am about to order some PCB's and VCA's for the Gyraf compressor, does anyone want to join in?

[Jason]

Is that the DIY 1176 comp?

[Thirteen]

Is that the DIY 1176 comp?

No, it's the GSSL stereo bus compressor. The 1176 boards can be easily ordered from Australia if you want to give that a go, and nice cases can be gotten from Europe. If you need construction help let me know.

[Jason]

Cool. I will look into getting some of those boards. Thanks for that.

I would love to build one of those GSSL comps.

How much for the PCB & VCA?

Cheers

Jason

[TimS]

Is that the DIY 1176 comp?

No, it's the GSSL stereo bus compressor. The 1176 boards can be easily ordered from Australia if you want to give that a go, and nice cases can be gotten from Europe. If you need construction help let me know.

I was going to do one of these about 4 yrs ago - got all excited about it, then sold all my gear to travel O/S.
Still sounds like an interesting project..
Tim..

[chris p]

FWIW, I've built a couple of these, as have a few other forum members.

The PCB layout might leave something to be desired, and the spec'd opamp chips are more Toyota Corolla than Lamborghini Diablo, but who cares when the results sound so good?

You'll use sockets for the IC's like good DIYers I assume, and if you look at the schematic you'll see that the signal path is very simple: input buffer, sidechain take off, VCA section, output buffer, that's about it, so if you want to upgrade the opamps (eg to OPAs) its really only the 4 in the input and output buffers that you need to worry about.

Good luck, and feel free to post any questions.

[Thirteen]

FWIW, I've built a couple of these, as have a few other forum members.

The PCB layout might leave something to be desired, and the spec'd opamp chips are more Toyota Corolla than Lamborghini Diablo, but who cares when the results sound so good?

You'll use sockets for the IC's like good DIYers I assume, and if you look at the schematic you'll see that the signal path is very simple: input buffer, sidechain take off, VCA section, output buffer, that's about it, so if you want to upgrade the opamps (eg to OPAs) its really only the 4 in the input and output buffers that you need to worry about.

Good luck, and feel free to post any questions.

I also built a couple about 4 years ago, and they have had lots of use here and overseas. I decided to build a couple more as they are useful across drum subs especially, I am going to build the Oxford versions, ie; with individual rather than summed sidechains this time. They can be built using 8 VCA's to make them more like the desk, but I don't know if the difference is worth it. One of Mine uses DBX VCA's, the other uses pre-trimmed THATS VCA's.

I agree though, the board layout is really cramped at one end, good to pick your components carefully, and of course machined pin IC sockets are a must, particularly for the VCA's.

[Ausrock]

I've been sitting on some of the early GSSL pcb's along with the THAT's for about 4 years............one of these days I might actually have the time and spare $$ to make it :-(

[JulienG]

I'm in.

[Jason]

I have made my mind up.

I am in too.

Cheers

Jason

[Thirteen]

I am looking for the cheapest places to buy boards. I have gotten them from the UK in the past, but the pound is so strong, and I need 2 sets per unit to build the Oxford version, I am looking for a closer supplier. As for VCA's, I will probably buy a tube of 25 from THAT's. I will post any updates as I find them.

[astrovic]

The usual source for PCB boards for this project these days is Gustav at the Lab:

http://www.prodigy-pro.com/forum/viewto ... sc&start=0

15 euro each + postage. Plus he does a lot of the other PCB's for Gyraf projects (see the link). I don't know whether that's a good or bad price, at he's pretty much the only regular supplier, I think. There was a guy selling them in Sydney (Benny) but it looks like he stopped a while back as well.

I suspect that the UK guy you bought them from previously was The Chef, IIRC he used to source them but stopped a while back.

I built a GSSL a little while back - nice unit and straightforward build (but very cramped around them ins and outs!). I followed Greg's GSSL BoM* for parts, ordered mostly from Mouser and Digikey and everything fitted fine with a little jiggling.

*See the GSSL meta thread at the Lab, http://www.prodigy-pro.com/forum/viewtopic.php?t=110, 3rd link from the top.

[mfdu]

(sigh) i'm so bored by my gssl's clean sound i pulled it out of the case and stuff a pile of trannies into it .

matter o'fact, didn't i promise it to Astrovic in return for the G9 boards?

mfdu

[astrovic]

you did, but that's cool, all my music gear is in storage ATM so it woulf just sit on the pile for now... :(

[rob]

mfdu....too clean?

easy...crank the VCA sym trim right out of it's optimal minimum distortion position ( or did you use the factory trimmed VCAs ??? )

if not lower the value of the current limit resistor feeding into the sym port of the VCA and take the trimpot to an extreme.... you'll get lots of nice 2nd harmonics.

Rob

[harry]

Thirteen, count me in,

i'll try and build an oxford version if ya convince me its easy enough
Is that one that uses two sets of boards so as to have a true stereo sidechain? like the original...

i wouldnt mind adding the api thrust / hp filter board as well - should make it better when used on the main mix buss

I'm a couple weeks away from ordering a stack of cases from that purusha bloke in slovenia - Gssl Case (oxford edition), Dual 1176, Night eq and Dual 1272 case...

if you want to add an oxford case to my order let me know as it will save you a heap in postage.

wouldn't mind consolidating a digikey / mouser order as well if ur up for that as well.

CHeers

[Thirteen]

Thirteen, count me in,

i'll try and build an oxford version if ya convince me its easy enough
Is that one that uses two sets of boards so as to have a true stereo sidechain? like the original...

i wouldnt mind adding the api thrust / hp filter board as well - should make it better when used on the main mix buss

I'm a couple weeks away from ordering a stack of cases from that purusha bloke in slovenia - Gssl Case (oxford edition), Dual 1176, Night eq and Dual 1272 case...

if you want to add an oxford case to my order let me know as it will save you a heap in postage.

wouldn't mind consolidating a digikey / mouser order as well if ur up for that as well.

CHeers

Thanks for that, I had already ordered some cases from Tat Purusha, I have seen the cases he makes and they look great, but keep in mind that he is a little slow to ship stuff being a small operation, so you need to factor that in. As for the parts, Jaycar has most of the parts for the GSSL, from memory the only things you can't get there are a decent meter, the VCA's and one if the op-amps. It would be nice to find a source for Sifam meters that aren't from RS, they are so expensive for most stuff, but they certainly carry everything. The Oxford version does use 2 PCB's to split the sidechaining up. I haven't ordered ant PCB's yet, still trying to figure out how many I will need, I thought that I might buy a couple of extras and stuff them at the same time for future use.

As for building the unit, the case is the most difficult, so if you buy one ready made that solves that part of it, next comes mounting the mains transformer (Jaycar toroidal works great) and correctly and safely wiring the mains rig. You can but a power module that has an integrated fuse holder and filter. The PCB that everyone uses is really cramped at one end, so some components won't sit flat.

The best construction advice that I can offer as far as the PCB is to get a multimeter, and check that you actually have the correct value of each resistor type before you put them in.

What I mean is this: get your little bag of, say, 10k resistors, check one with your meter to make sure that they are indeed 10k, and then load them onto the board, then move on to the next value and do the same thing. Don't blindly believe the label on the bag. This is very important. If you finish the unit and turn it on and it doesn't work, it is MUCH easier to fault find if you can at least discount having to go looking for wrong resistors. Also, worst case scenario is if the unit works, but it doesn't work quit as it should, but you never realize this and your unit is forever wonky because of a wrong resistance somewhere.

[Thirteen]

Oops, hold on... Checking in at the Lab, looks like Keith has a "Turbo" PCB to simplify doing the OXford mod and perhaps some other functionality about to be released in the next week or two. This might mean not having to build 2 GSSL boards per unit, so watch this space or check the Lab.

[harry]

Yeah,
thats what i was thinking - keith's board...
will have to go for that one.

As for the parts - canford in the uk www.canford.co.uk is a good place to get transformers (oep) and meters (sifam) and knobs (sifam) very cheap.

but i might get my meter from that canadian bloke on groupdiy - the be!@#$%^& meter, he's out now but some on the way soon.

thanks for the advice regarding putting these things together - i usually build the power supply first and test it extensively, or build the circuit and use a bench supply to test it.

im pretty good at reading resistors from the color bands but yes - i do check every part before i put it in the board..

might do an order from mouser or digikey and get better quality capacitors (wima) (nichicon) that the jaycar stuff...

altronics is a good source of capacitors (power supply) that actually fit in a 1ru case...

you wouldn't happen to know which diy project is the best neve 1272 / 1290 out there? ive got a heap of carnhill / marinair transformers that need to be put to good use.

cheers

[Thirteen]

I thing the Sifams would be cheaper from RS or Farnell in Australia, the Canford site lists the PPM14 at about $160 australian before freight and currency conversion. the Sifam AL19 with bezel is $142 inc tax from Farnell in Sydney, plus $8 freight.

[otto ruiter]

http://www.switchesplus.com.au/ sell Sifam in Australia. Might be worth a try.

[harry]

The PPM14 is an expensive meter, Canford do the AL19 for 22.5 pounds or about $50, i think from memory that includes tax which is deducted from a non eu sale... they are sent out via royal mail which is pretty cheap...

i didnt think a vu meter was suitable for an ssl comp wasn't it a different type for that circuit?

[Thirteen]

Yes, your right, I think the PPM14 is a VU, I used the AL19 with the outside bezel for my earlier projects, from memory it's 1mA FSD. On Otto's advice I called Switches Plus, they do the AL19WF (meter inside, bezel outside) for $68.63 plus GST, they are out of stock for a month though. So you are right, Canford looks like a good bet.

[Thirteen]

http://www.switchesplus.com.au/ sell Sifam in Australia. Might be worth a try.

Thanks Otto, good lead.

[chris p]

For interest, I read a good post on another site that explained the difference between the actual SSL compressor and the GYRAF version: the real thing detects peaks separately from L and R, and then uses the greater of the two as the sidechain input. The GSSL instead uses a sum of L and R into a single peak detector.

Neither approach is right or wrong, its just different - but one effect is the standard GSSL is actually compressing the mids (L+R) rather than the sides (L-R), and hence part of its "niceness" is due to it opening up the width of the recording a bit. Once that was explained to me, I understood more about what I was hearing with the thing.

[Thirteen]

The new turbo boards are now available from The Lab, they save having to build a second GSSL PCB for the Oxford mod. US$9.95 each here: http://www.expataudio.com/expatshop/

They can be added to an existing GSSL also. If you have a sidechain board in your GSSL you will need a second one if you add the turbo board.

[mfdu]

mfdu....too clean?

easy...crank the VCA sym trim right out of it's optimal minimum distortion position ( or did you use the factory trimmed VCAs ??? )

if not lower the value of the current limit resistor feeding into the sym port of the VCA and take the trimpot to an extreme.... you'll get lots of nice 2nd harmonics.

Rob

hey Rob, thanks. i'll whip it out again soon (now that barney has donated a spare sidechain filter board) and give it a poke.

i know there be goodness within, but i've found it hard to be . . . excited by the sound of it.

i dunno. for some reason i prefer to send the main bus through to 1/4" tape.

cts
mfdu

[harry]

hey thirteen,

did anyone take you up on a group buy for this?

i would be up for it if it hasn't already happened...

wouldn't mind doing a board with the turbo add on and two sidechain boards....

haven't looked through the 180+ pages on prodigy - hope it is a fairly straightfoward build??

[Thirteen]

The build is pretty straightforward. The Turbo board is a must. The only vague part is what components to leave out if you use pre-trimmed VCA's, and the board is a little tight at one end as far as component placement. Only less common parts are the VCA's really, and if you want a Sifam meter or exotic pushbuttons.

[AndyCroz]

has there been a group buy or this project yet?? im looking to do my first Diy and i thought this one could be a good start. Can anyone give me a good figure for what it would cost roughly to get all the pieces and boards for this?? im in the process of budgeting on how many noodles i should buy for the next few months..