Building the WHAT compressor

[HappyTom]

Hi and thanks!

I really didn't know if I was supposed to use one or another or both..
I tried to put a 5k pot in parallel but all i got was more gain but distorted.
(i guess i need a bigger one)

I got low gain in my, but i read some pages ago the gain was high so i guess something is wrong with it.. think i have to fix the small things up before i start play with it..
I havn't put a swich for the filter as i cant see what kind of filter it is..
Can someone enlighten me?

HT

 

[MrZpliff]

[quote author="HappyTom"]Hi and thanks!

I tried to put a 5k pot in parallel but all i got was more gain but distorted.
(i guess i need a bigger one)

I havn't put a swich for the filter as i cant see what kind of filter it is..
Can someone enlighten me?[/quote]

A 5k pot i parallell means that you get just about 5k maximum.
Put a 10k pot in series with an 18k resistor instead of the 27,4k resistor if you want to play with it. I think it's fine as it is.

The filter takes bass away from the sidechain and makes a big difference in how the compressor works (and sounds). It sounds more open and transparent with the filter in, wich in some cases is good and some not :grin: .

 

[HappyTom]

thanks!
I might just skip the idéa of having a variable aprilresistor..

It feels kinda odd to conversate with a swedish guy in english :grin:

HT

 

[tommypiper]

I'm just getting organized for this project. All the BOM links are dead in this thread. Can someone send me a BOM?

I understand there are various options but I am still confused and don't see a method to understand it yet.

EDIT: Thanks to everyone who sent emails and PMs. The corrected URL for BOM is http://www.thediypill.phx.com.br/forumfiles/what_bom_rev1.htm

cheers.

 

[rpd]

Hello eveyone!
I could put this in the black market but.....
I bought these boards from Bauman (fabio) last summer. I am a newbie and this project scares me a little. I have them and haven't touched them. If someone is interested in buying them from me (for what Fabio sold them for) then send me a message.
Ryan

 

[Ptownkid]

what scares you about it?

 

[Ptownkid]

is there a particular reason for using 1n4004's instead of sayyyyy 4007's? he only diff ican see on the datasheet is the peak repetitive reverse voltage...

 

[smallbutfine]

:grin: I think you are completely right, it's just up to specs...you can use 1N4004 or up to be on the safe side. This is the minimal voltage resistence recommended i think.

EDIT: *voltage resistance* :razz: i think you get the point. I use 1N4004 or anything up to 1N4007, whatever i have laying around. you can always upgrade diodes to faster or higher voltage grade (IF it doesn't have a more special meaning in the circuit like in a diode limiter, where diodes are sometimes meant to dismatch).


Kind regards

Martin

 

[Ptownkid]

That's what I figured

Where the hell did everyone find the caps needed with a 10mm footprint though?

 

[rpd]

What scares me is the the lack of documentation.
I don't have a ton of time, or experience.
People have said it is not an easy build so i'd like to pass it on to some one who is up for the challenge.
Someone who has done more of this type of thing could do it fairly easily i'd bet.

 

[Ptownkid]

Don't give up on it, there's lots of help, and I'll be glad to provide some guidance once mine is done.

Looking over the board and ordering the parts...I don't see this being all that complicated, and I'm no PRR.

 

[StephenGiles]

I have built several of these on veroboard. One I had a working pattern it's easy. I really can't be fussed with PCBs.

 

[rpd]

Alright maybe i will give it a shot.
Done with school here in a couple weeks, and i have over half the parts already.
Thanks for the encouragement!

 

[Kir_For_Pleasure]

[quote author="Bauman"]

Hey guys,

I will try to help in any way I can, probably putting down some guide or instructions. Just need a weekend to get togheter after some hard work and will get back here.

:guinness:
Fabio[/quote]

Waiting :wink:

 

[AnalogPackrat]

Let's revive this thread. I'm almost done stuffing two of Fabio's WHAT pcbs. I have left off several parts related to the ratio and threshold controls. I plan to experiment with those controls on the bench before committing them to solder.

Since I'm making a pair and would like to use them linked for stereo, I did my best to match the VTL5C9s for DC resistance (not time constant). I bought six and found that they varied wildly. I simply collected data a four operating points. I set up my bench supply for +15V and drove the LED with four different current limiting resistors, 1K, 10K, 100K, and 1M. I measured the photocell resistance at each setting.

What I found was that they matched fairly well at the bright end (low resistance), but diverged at the dim end. I also noticed the long time constant effect of these things. Take a unit that hasn't been "on" for several minutes. Run it with the 1M resistor and note the cell resistance. Now switch to the 1K resistor and leave it on for about a minute. Quickly switch back to the 1M and watch the cell resistance--it will be much lower than the first measurement and will creep up. I wonder how much of this is caused by the photoelectric effect and how much is tempco of the CdS material?

No two cells matched very well at 1M. However, this would be at the "barely compressing" end of things, so I chose a pair that matched very closely at 1k and 10k and fairly closely at 100k. Note that of the 6 I bought, there was only one decent pairing, so if you plan to make a stereo unit, I'd buy 10 to assure getting a good pair.

A P

 

[StephenGiles]

Does it really matter that much? I am using a 5C4/2 and NSL32 in a stereo pair and I just adjust the compression until it sounds about right!

 

[AnalogPackrat]

I should have also said that I plan to use rotary switches for gain, threshold, and ratio. That's why I'm being a bit more careful with the vactrol matching. I suppose I could adjust the R ladders on the each channel to make up the difference but that sounds like a royal pain! I have the, perhaps silly, notion of using this thing for a stereo bus compressor and maybe even for trying my hand at mastering (really silly).

I also got some NSL parts--dang--should have checked those as they might have matched a bit better.

So, Stephen, how do you like your WHATs? I haven't heard anyone here talk about using them. Which options did you go with? What iron? 1731s? How have you been using them? Anything you would have done differently? Any photos?

Cheers,
A P

 

[kvintus]

Yes. Matching of the two GR-elements in a stereo compressor does really matter much, at least in my opinion. If they are unmatched the stereo image will tilt when compressing. But if unmatched works well for you, then everything is fine.

Just my 0,015?

/Anders

 

[delaymix]

[quote author="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[/quote]

Hello,

In CC condenser...

Really is no difference when using a condenser of 620pF to one of 680pF?

If truely it is certain that difference does not exist some, That felt it has has in the scheme the value of 620pF?

Thanks, Kind regards

 

[Bauman]

Hi,

well you can use 620pF... it will work.

cheers!
FAbio