OPTO "Grinder"

[Gustav]

Thanks very much for your response Gustav.

I soldered the 0 ohm resistors in place yesterday and did the rough calibration too.


I did some quick tests last night and it's all working as expected.

I still have to work out the front panel artwork but other than that it is all finished.

Thanks.

Jimmy5K

Glad I could help

I just realized this weekend, the threshold rotation is backwards (Ive built a few of these, but I guess its not something I pay attention to). It may be a good idea to rename it to something else doing the front panel.

Gustav

 

[mrkrawn]

Hi gustav i'm calibrate my dual opto grinder.
It sound great.
can you explain simply
Dial “Set OPTO” to 75% (or return and adjust by ear)

I just want to know if i must turn to 75% to te left or right attached the pic of the trimmer

 

[Gustav]

Hi gustav i'm calibrate my dual opto grinder.
It sound great.
can you explain simply
Dial “Set OPTO” to 75% (or return and adjust by ear)

I just want to know if i must turn to 75% to te left or right attached the pic of the trimmer

75% "up", or clockwise.

I only listened to adjust this, but according to Jakob, the knee is harder to the left of the range, which you may prefer.

Gustav

 

[mrkrawn]

thanks  Gustav
it's going to help me save time

 

[Ave Crux]

Hi, I'm very interested on hoping to start this as my next project, but I have a question. Suppose I get a VU buffer kit from JLM Audio will it be possible that instead of having a switch for the GR/Output meter that I can have two meters running that one is showing strictly GR and the other the output? Or would that be too difficult?

 

[Gustav]

Hi, I'm very interested on hoping to start this as my next project, but I have a question. Suppose I get a VU buffer kit from JLM Audio will it be possible that instead of having a switch for the GR/Output meter that I can have two meters running that one is showing strictly GR and the other the output? Or would that be too difficult?

For starters - Its very easy to draw the cables to do it. I will make you a drawing with the points marked on the meter switch, if you can't trace them out yourself.

I would check the implications of running both loads in the design as-is, since the VU is not buffered, and I dont know what running the GR and VU at the same time would  do to the audio signal (might just be the same, but I would check).

If you're inserting a VU buffer, I don't see why there should be any problems at all, though.

Sounds like something that may end up looking cool. Make sure to share when you're done

Gustav

 

[Ave Crux]

Hi, I'm very interested on hoping to start this as my next project, but I have a question. Suppose I get a VU buffer kit from JLM Audio will it be possible that instead of having a switch for the GR/Output meter that I can have two meters running that one is showing strictly GR and the other the output? Or would that be too difficult?

For starters - Its very easy to draw the cables to do it. I will make you a drawing with the points marked on the meter switch, if you can't trace them out yourself.

I would check the implications of running both loads in the design as-is, since the VU is not buffered, and I dont know what running the GR and VU at the same time would  do to the audio signal (might just be the same, but I would check).

If you're inserting a VU buffer, I don't see why there should be any problems at all, though.

Sounds like something that may end up looking cool. Make sure to share when you're done

Gustav

Thanks Gustav, one more question though. If I get the large VU meter in your site which has a lamp, is there any way to power that from the board? By that I mean, when I made the GSSL there was a 12v supply I was able to use to power my LEDs. I can't seem to see one in this though.

 

[kante1603]

For the lamp(s) you must first know its' data.Is it led or a bulb tube,which current and which voltage is necessary?
Next tap off a psu rail and ground,calculate the preresistor,solder,done.
You'll need to tap off the rails for Joe's buffer anyway,they're on board snd easy to access (have seen the build manual,same bridges to do as on the fet compressor I guess,perfect points to tap off).
Btw.,don't worry to have the buffer on the output,it has an impedance of roughly 100kOhms so the output circuit will not "see" it as a serious load.Have done exactly the same on my first GSSL,1 big nice Sifam for compression and two (because it is stereo) small round meters that are even switchable between in and output.
Looks very nice indeed!


Best,


Udo.


Here's a blurry pic,but to give you an idea.....

 

[4earstudios]

Hi All, i hope you could help me with this one. ive built the old layout opto grinder, and the unit seems to work, but there is no compression going on . i can clearly see that gain reduction occuring on the VU  - also changing with Treshold and Ratio - but i dont hear any gain reduction. its like the unit is in bypass - just hearing the input ( wich reacts to the output poti ). i had a bulding issue so that one solderpad went away and i had to connect the components directly ( i will post picture soon to clarify the components ). maybe you have an idea - sry for my english

daniel

 

[mrkrawn]

Hi Gustav

I try to upgrade my dual opto grinder.
I looked your shematic, and i planed to replace  the two 6.8uf electrolytic in the signal line by a bipolar 3.3uf high end audio capacitor.
are these two caps are just in serie?

thanks

 

[mrkrawn]

Hi everybody

I finished my update of this beast now he sound as i like.
stereo ratio calibration is hard to find
I report 2 problem for my  first version "opto grinder"
The stereo link don't work as expected.
It  compress more right channel.
I just took a spdt switch and link each link point on each mainboard to the switch.
The other problem is the ratio.the first position really compress more the signal.
in theory it's 2/1 the more gentle,and i have an aggressive compression.
the 5  position work but seem to be reversed
is the first position ratio is 20/1 ?

Best

 

[gyraf]

The ratio switch also at the same time changes the threshold, so depending on levels, low ratio may compress "more".

For stereo linking trouble (is the circuit meant to be stereo linked at all?) - I would look in the original LA4-manual for reference..

Jakob E.

 

[Lordward]

Hello!
It's been awhile since anyone has posted here but I'm still hopeful that I might get some help  :

Anyway, I received a PCB of this HOL from Gustav as a gift (very grateful Gustav!) and so I decided to give it a go.  All seemed quite easy and I read through this thread before I started.  Right to the point: I can't get this unit to pass sound. 

I've tested the voltages to read: 21.85 VAC between secondary CT and one of the ends.
At the +18V test point I get +16.49V DC
At the -18V test point I get -16.76V DC

I'm assuming this is ok.

As I've said, I get no sound to pass through.  No matter how I set the thres/gain/ratio.  Hoping to get some help debugging this thing!

Cheers,
DW

Here's a pic of my build -

 

[kante1603]

Hello,


looks like you haven't connected the psu to the circiut.
If you get dc voltage at only one test point for both rails but nowhere else (e.g. ic sockets or the other "end" of the test point) then you have to put in two bridging wires or zero ohm resistors there,looks like they're missing!


Best regards,


Udo.

 

[Lordward]

Hello,


looks like you haven't connected the psu to the circiut.
If you get dc voltage at only one test point for both rails but nowhere else (e.g. ic sockets or the other "end" of the test point) then you have to put in two bridging wires or zero ohm resistors there,looks like they're missing!


Best regards,


Udo.

Thanks Udo,

You know, I was looking at that and just was not sure... A bridge, of course.  As usual it has to be something that basic. 
Thanks again!

DW

 

[Lordward]

Yay!  All is good.

Sounds pretty cool so far.  At least I was able to get rid of a lot of bits that I've had laying around for ages   It's not pretty but it works!

Cheers,
DW

 

[skeeler87]

Hi Gustav

I try to upgrade my dual opto grinder.
I looked your shematic, and i planed to replace  the two 6.8uf electrolytic in the signal line by a bipolar 3.3uf high end audio capacitor.
are these two caps are just in serie?

thanks

Im curious about this! What advantage does it give and is it worth doing it?

 

[gyraf]

Isn't the 6u8 in signal path a Wima polyester already? I'm pretty sure it is in above pic..

Jakob E.

 

[tuanuibi]

Hi guys,
I've build a dual mono unit. One channel works perfectly, and I think it sounds fantastic... but I'm having trouble with the other channel.

It's only passing audio intermittently, and not responding the knob movements.

Could this be a cause of a dead opto? I had to desolder and re install it because installed it backwards initially. I'm thinking that might be my problem?

The power supply is putting out + & - 17V (the same as on the other unit).

I've attached a picture if anyone feels like taking a look.

Thanks to Gustav for this project, I love it - cant wait to get both firing!

 

[Gustav]

Hi guys,
I've build a dual mono unit. One channel works perfectly, and I think it sounds fantastic... but I'm having trouble with the other channel.

It's only passing audio intermittently, and not responding the knob movements.

Could this be a cause of a dead opto? I had to desolder and re install it because installed it backwards initially. I'm thinking that might be my problem?

The power supply is putting out + & - 17V (the same as on the other unit).

I've attached a picture if anyone feels like taking a look.

Thanks to Gustav for this project, I love it - cant wait to get both firing!

Is the meter responding, even if the audio fails? In that case, it could be one side of the opto.

You have a working unit, which is golden for trouble shooting, since you can just compare voltage readings in the two to track down the error.

Gustav