Building the WHAT compressor

[Guest]

Ted Fs
Descritpion fo the original reason the original was built
http://www.groupdiy.com/index.php?topic=10777&postdays=0&postorder=asc&start=0
And an schematic for a
"'bridge' circuit that allows me to 'lever' the compression ratio over an extreme range. "

 

[HappyTom]

Oh.. I've got rev 1..
On rev 2 it's all clear, thanks!
I've missed that one.

I think the jumpers JI1-3 is configuration of the primary windings, serial or parallel. It looks like the suggested way is to put in JI1 only and leave the others out on lundahls site. I'll probably try the other way around also and stuff JI2 and JI3 and leave JI1 out. This is just guesses though...

HT

 

[HappyTom]

Doublepost.

 

[Bauman]

!!!

 

[Bauman]

..

 

[Bauman]

how I delete this?

 

[HappyTom]

R1 is 10K according to the shematic.

HT

 

[Bauman]

Sorry guys,

I'm not happy to kinda abandon you on this. Just too many things to fix and pay
Paul is right, the schematics says it all, and his answers are precise. I remember some folk that said my boards were like hardcore DIY (btw I like hardcore . Totally true, I mainly have the schemo as document, the stuff is not like a easy to build kit cos all the options, my bad! I know we have some many different levels of knowledge here and I'm not being nice to you guys that are starting out.

I dunno when I will have the chance to sit down and spend a night or 2 to all the info on paper, but I'd be glad to answer any questions, and then I can cut/paste it to a FAQ or something. Just hit me on [email protected] any time, no probs!

And btw, take a good look at this:
http://www.thediypill.phx.com.br/forumfiles/what_sch_rev2.pdf

This is the right schemo for that board, I'm sure it will raise some questions and answer another ones.

Hope to get back on the forum on a daily basis soon, I really miss this place and people!

and Chris, no flames taken! :thumb:

cheers!
Fabio

 

[pmroz]

.
Hi Chris,
Most of the info quoted is from the schematic. Oh, Fabio just jumped in... great!

I also try to trace the path on the boards, to understand better... it's tricky in the mult-trafo section. And the boards are double-sided, messes me up at times. Schematic is the best road map... you can also see which caps are polarized/non-polarized, whether pots are lin/log/revlog, etc. For example, C1 is non-polar, so a 1uf film cap would work. Use your favorite variety, since it's in the signal path. A bi-polar electro might work, but could affect/color the sound more.

The input next to 'XLR in' on board, is for unbal in (no trafo). If you don't have a jack on that input, you don't need C1 or R1. And please somebody yell if that's wrong.

The whatopto_bom_rev2 parts list looks current. Probably generated from schem.

For the OEP, pull all parts ending in '1' if you installed them. RL1, RL2, RC1, CC1. Leave RL, RC, and CC in. Then tell us how you like it!

Happy Tom, we're thinking the same about jumpers. Looks like you can get 150ohm primary, 600 ohm primary, etc on the Lundahl (and OEP, now that I look) with different jumpers. With 150ohm + a DOA for U1, this board might have enough gain to be a combo mic pre + comp. Try plugging a mic straight in.

Have fun and let us know how they sound.

Holy double, triple, and quadruple posts! Posters, you can click on a post and edit or delete the doubles.

 

[HappyTom]

As I can see it on shemo you need R1. Looking at pcb confirms that.
On shemo IN is located between C1 and R1.

There was some trouble with the thread a couple of hours ago, thats why all the doubleposts, and now it's too late to delete.

HT

 

[mfdu]

fabio - good to see you're back, and i hope everything is ok at home.

me and the wife have been through a bit of trouble too, so i especially hope everything is ok.

so th BOM i have been grooming is looking great from the added info paul has made clear to me.

i would love to find someone to host this - i reckon it will answer more questions than this thread and schematic combined.

will remove the items you chaps recommend, and see how it goes.


and fab - nothing wrong with a little hardcore. in this context, it really jumped my skills up a notch!

chris.

 

[mfdu]

fab

worked BOM on its way to you, featuring all the new bits of info from paul and the others.

hope you can find a spot to host it.

includes BOM for melcor 1731 op amps.

hopefully this weekend will fault-source the pair of boards and will report results next week.

chris.

 

[Kir_For_Pleasure]

[quote author="mfdu"]fab

worked BOM on its way to you, featuring all the new bits of info from paul and the others.

hope you can find a spot to host it.

includes BOM for melcor 1731 op amps.

hopefully this weekend will fault-source the pair of boards and will report results next week.

chris.[/quote]

Maybe now a working bom is out there somewhere in cyber :grin:

Someone that built the compressor ? Please give me some coments of what do you think of it.

 

[mfdu]

i have built it

harder build than the 1176 or gssl, due to all the options available

build with OEP input trannie. enough gain to run as a mic pre for a SM57/58!

compression amount LED doesn't light up, but it certainly compresses. very smooth opto characteristic.

mainly use it as a dual mono tone box and signal booster.

if you ain't hot on your electronics, start on an 1176. then do a couple more 1176's. then, and only then, think about what you have learnt and try the what?

thats just my opinion.

chris.

 

[MrZpliff]

Maybe a stupid question, but...
Can I use a 680 Pf instead of a 620 PF as CC, when using the
OEP A262A3E ?

...for no other reason than I forgot to rder a 620PF :roll:

 

[StephenGiles]

Only if there's an R in the month!

Really it won't make any difference given 10% tollerances.......now someone clever will say that I'm wrong!!!
Stephen

 

[MrZpliff]

[quote author="StephenGiles"]Only if there's an R in the month!
[/quote]

That's what I thought too :!: Thank god I haven't soldered it yet !








:green: :guinness: :guinness:

 

[MrZpliff]

OK ! :grin: The What is finnished.... well, almost.
No case yet, but I hooked it up and tried it and I must say it sounds
really promising. It does have its own caracter for shure, which is the main reason to build stuff like that, I think. Need to play with it more though.

Used Fabio's board, with OEP input trafo and NE5534's for opamps.
Might try and build some melcor's later.. (must finnish the LA-2a first).

The gain-pot is running backwards and I think the LM-regulators needs a small heatsink (one each), otherwise all seems fine.

:?: Does anyone know how to set the bias-trimpot ? I guess it's just to adjust it and listen until it sounds the best.

Anyway another cool and useful project :thumb: :guinness:

 

[HappyTom]

Anyone figured out a value for the aprilresistor.

HT

 

[MrZpliff]

[quote author="HappyTom"]Anyone figured out a value for the aprilresistor.

HT[/quote]

I used the value on the schematic, without the pot.
I guess you can use a pot instead of the resistor or hook one up in parallell...

Lycka till :grin: