D-LA2A Support Thread

[martthie_08]

and congrats on the D-LA2A.

thank you, it has been joy and pain to build

we want to see some pics, you know this ;-)

yeah, I know, but it's late and I really want to take some pictures with a nice camera, but hell, here's the iphone version as a preview:

here some technical info on the build:
Mueller Rondo power transformer
Jensen JT-11P-1 input transformers
UTC A24 output transformers
DRIP t4b (slow)
new 12AX7 tubes from Tung Sol
new 12 BHA-STR from TAD
old 6AQ5A from Tung Sol
Zener diode instead of neon lamp
Hairball VU meters & knobs
custom designed UREI ripoff frontplate
Robeshop industrial 19" case
mostly shielded cable wiring except for input / output / VU gain reduction

Noise floor is ok both channels sitting at around -78dB RMS, which is due to a little 50Hz hum.
the gain range is nice using the 1:1 with the standard 100k pot, around 12 o'clock on the gain pot is unity gain running in and out of the DAW. It starts to get a little sensitive with increasing gain. Anyways much less touchy than say an ADL 1500 which I've had before.

It is pretty tight in the housing and this beast gets pretty hot over time, I will have to drill a couple extra holes in the top and sides of the case.

The VU lamps are connected after the rectifier before the regulator of the 5V relay section. This is not ideal, as when the relays are switched in, the light on the VU goes down a notch. Those 5V relays really pull a lot of current, I'll have to check whether the power transformer is fine with that, it's getting a little warm around that toroid.

I changed the 68k to 11k on the input as per Jensens note, but did not really notice much of a difference.

Did I mention it sounds fabulous?
cheers, Marten

 

[drumminkiger]

This may be a horse that has been beaten to death and I am just missing it, but, say for instance I am a cheap ******* and just need one channel for now, but want to build a 2nd in the future. Are there parts that I can omit from the BOM to keep the cost down in the mean time (such as the most expensive ones like a TB4) so I can build just one channel now, have a functional unit, and then add the second channel components later? Or is it pretty much an all or nothing deal?  I figure i'll get all the simple resistors and caps in one sitting, but if i can get some of the bigger ticket items one channel at a time, that would be nice. If not, I still totally want to build this project, but it'll just take longer

 

[abechap024]

This may be a horse that has been beaten to death and I am just missing it, but, say for instance I am a cheap ******* and just need one channel for now, but want to build a 2nd in the future. Are there parts that I can omit from the BOM to keep the cost down in the mean time (such as the most expensive ones like a TB4) so I can build just one channel now, have a functional unit, and then add the second channel components later? Or is it pretty much an all or nothing deal?  I figure i'll get all the simple resistors and caps in one sitting, but if i can get some of the bigger ticket items one channel at a time, that would be nice. If not, I still totally want to build this project, but it'll just take longer

Sure you could build one channel at a time. I would stuff all the resistors for both channels now, as the expense is probably going ot be mitigated by shipping. But up to you....why don't you just get a turret board and do it point to point (i know i know it will take more brain energy, but will be cheaper)

 

[johnnyscotch]

Hey guys, I'm sourcing all the parts now to build a DLA2A

Where did you find Drips T4Bs?? They aren't on the site anymore??

What other options would I have that won't double the price of the project??

THanks!!

Eric

 

[Kamel]

http://www.kenetek.com/T4AT4BUnits/KenetekT4BModules/tabid/300/Default.aspx

the T4b does'nt double the price, transformer can

 

[desol]

I don't believe the Kenetek are available either.

 

[MicDaddy]

Looks like Keneteks are back for sale... which is odd cause now it looks like there are no more Drip V2s...   

 

[johnnyscotch]

So, Keneteks are about the only option?

Has anyone heard from Drip? Will his be re-stocked?

Is he on this board?

 

[audiophreak]

Hi,
  I sent an email to Gregory ( DripElectronics )  about a month ago , he replied that it would be a couple weeks , I still dont see them listed on his web page , I sent another email yesterday and have not gotten a reply yet , I also need some for this project , but not really in hurry , hopefully  soon.  I will post back if I hear anything.

 

[johnnyscotch]

Hi,
  I sent an email to Gregory ( DripElectronics )  about a month ago , he replied that it would be a couple weeks , I still dont see them listed on his web page , I sent another email yesterday and have not gotten a reply yet , I also need some for this project , but not really in hurry , hopefully  soon.  I will post back if I hear anything.

Cool, please do!

cheers

 

[johnnyscotch]

I was reading through the thread and I noticed some info about the 5v relays.

These are the ones in the current BOM: http://www.mouser.com/ProductDetail/Omron/G5V-2-DC5/?qs=%2fha2pyFaduiP%2fpKRK%2fe1cWl7h9DP4yrNWPXtM1DhKn7n0Pslql4ewQ%3d%3d

I ordered them, are they going to work??

cheers!

 

[abechap024]

Hi,
  I sent an email to Gregory ( DripElectronics )  about a month ago , he replied that it would be a couple weeks , I still dont see them listed on his web page , I sent another email yesterday and have not gotten a reply yet , I also need some for this project , but not really in hurry , hopefully  soon.  I will post back if I hear anything.

why not build your own? i know there is a lot of hockus pocus voodoo surrounding it, but because its feedback type compressor, its really not that hard...i only say this cause i built 2 and they sound surprisingly nice. I woundt sell them, but i sure would run some audio through them, thank you very much! bought the EL panels on fleabay for 7 bucks and the nsl photo-resistors that were recommended.

 

[audiophreak]

Hi,
  I sent an email to Gregory ( DripElectronics )  about a month ago , he replied that it would be a couple weeks , I still dont see them listed on his web page , I sent another email yesterday and have not gotten a reply yet , I also need some for this project , but not really in hurry , hopefully  soon.  I will post back if I hear anything.

why not build your own? i know there is a lot of hockus pocus voodoo surrounding it, but because its feedback type compressor, its really not that hard...i only say this cause i built 2 and they sound surprisingly nice. I woundt sell them, but i sure would run some audio through them, thank you very much! bought the EL panels on fleabay for 7 bucks and the nsl photo-resistors that were recommended.

  Normally I would say " Challenge Accepted " but I just dont have the time right now to experiment    .. but I'm busy work wise , so not complaining.  This is my first foray in to optical compressors , and after gettin my butt kicked from the mnats dual 1176 rev j. I just  finished ... I'm taking my time with this one, but after I get this one running normally, I my just try my hand at that and compare. If I do, I may have some questions for you.  ;D

 

[johnnyscotch]

why not build your own? i know there is a lot of hockus pocus voodoo surrounding it, but because its feedback type compressor, its really not that hard...i only say this cause i built 2 and they sound surprisingly nice. I woundt sell them, but i sure would run some audio through them, thank you very much! bought the EL panels on fleabay for 7 bucks and the nsl photo-resistors that were recommended.

I'd take a crack at it, where could I find more info or a schematic or something? What about the housing/socket pins for it?

 

[audiophreak]

HI All,
        Well ... I flipped the switch .. and Nothing blew up !!!  YYYyaaaaa  ;D
I took voltage readings , they are :

V101 - pin 1 = 113.9vdc      v102 - pin 1 =  93.3vdc    v103 - pin 1 =  87.5vdc    v104 - pin 1 =0.004
          pin 2 =    0.0vdc                pin 2 =    0.003vdc            pin 2 =  -0.001vdc            pin 2 = 6.08
          pin 3 =    0.927vdc            pin 3 =    3.78vdc              pin 3 =    0.739vdc          pin 5 =127.4
          pin 6 = 111.4vdc                pin 6 = 204.6vdc              pin 6 =    87.5vdc              pin 6 =102.0
          pin 7 =    0.001vdc            pin 7 =  71.5vdc              pin 7 =    -0.001              pin 7 =0.004
          pin 8 =    1.04vdc              pin 8 =  98.1vdc              pin 8 =      0.74vdc


V201 - pin 1 = 114.3vdc      v202 - pin 1 =  90.9vdc    v203 - pin 1 =  94.6vdc    v204 - pin 1 =0.003
          pin 2 =    0.001vdc            pin 2 =    0.001vdc            pin 2 =  -0.001vdc            pin 2 = 6.18
          pin 3 =    0.923vdc            pin 3 =    3.73vdc              pin 3 =    0.704vdc          pin 5 =124.8
          pin 6 = 118.8vdc                pin 6 = 204.7vdc              pin 6 =    94.6vdc              pin 6 =105.0
          pin 7 =  - 0.001vdc            pin 7 =  69.1vdc              pin 7 =    -0.001              pin 7 =0.003
          pin 8 =    0.967vdc              pin 8 =  95.15vdc              pin 8 =      0.704vdc

R133  = L= 249.9 / 87.5vdc      R=248 / 94.7vdc
R131  = L= 0.74vdc                  R= 0.71vdc
R134  = L= 250.7 / 126vdc      R= 250.3 / 123.6vdc
R136  = L= 6.1vdc                    R= 6.22vdc
R109  = L= 197.6 / 114.3vdc    R= 198.9 / 114.5vdc
R138  = L= 102.2vdc                  R= 105.4vdc
R118  = L 98.6vdc                      R= 95.9vdc
R117  = L 251 / 205.1vdc          R= 250.5 / 205.2vdc
R113  = L 197.5 / 118.7vdc        R= 198.6 / 118.9vdc

  and    63.8vdc on both diodes in place of Neon lamps

EDIT :  ... and heaters are all 6.6vAC

  I'm pretty sure its all within +/-  limits , and it passes clean audio - tons of gain , I did the 75k resistor and 25k pot - waiting to purchase the T4B's  -  noticed that the 6AQ5a's get REAL HOT  - and the Lytic caps next to them are getting hot from the tubes, not sure if this is something I should be concerned about, just thought I'd mention it.

  ... just looking for more experienced eyes to look over these readings, also wondering what type of load / resistor to put across inputs to check noise floor , or if that can be done without the T4B's in place , also I'm using the Rondo PT , and notice it has a little physical  " Buzz " noise  that I've heard on other types of PT , but not Toroidal type.

  Thanks as always ,
                                          Chip

 

[abechap024]

why not build your own? i know there is a lot of hockus pocus voodoo surrounding it, but because its feedback type compressor, its really not that hard...i only say this cause i built 2 and they sound surprisingly nice. I woundt sell them, but i sure would run some audio through them, thank you very much! bought the EL panels on fleabay for 7 bucks and the nsl photo-resistors that were recommended.

I'd take a crack at it, where could I find more info or a schematic or something? What about the housing/socket pins for it?

Look for octal 8 pin relay housings. Easy to find, lots of varieties. I bought some that were clear and gave them a couple coats of black spray paint in and out. I bet with just a little more effort an inexpensive testing rig could be made to test the various photo-resistors. Seems like the modern ones are a lot closer in spec to each other, just there is that one or 2 oddballs that could throw things off.

But for the 40 or so dollars I have invested for 2 I feel its worth it. Especially since the gear I make for myself I prefer it to have personality that I have to get to know; sometimes I find some real winners that just sound really cool (like using fets in 1176s that don't have the "optimal" curve)

 

[johnnyscotch]

Cool thanks. That's probably over my head I guess. Besides finding a housing for it and some photo-resistors, I wouldn't know where to start.
I don't know WHICH photoresistors to get!! LOL

why not build your own? i know there is a lot of hockus pocus voodoo surrounding it, but because its feedback type compressor, its really not that hard...i only say this cause i built 2 and they sound surprisingly nice. I woundt sell them, but i sure would run some audio through them, thank you very much! bought the EL panels on fleabay for 7 bucks and the nsl photo-resistors that were recommended.

I'd take a crack at it, where could I find more info or a schematic or something? What about the housing/socket pins for it?

Look for octal 8 pin relay housings. Easy to find, lots of varieties. I bought some that were clear and gave them a couple coats of black spray paint in and out. I bet with just a little more effort an inexpensive testing rig could be made to test the various photo-resistors. Seems like the modern ones are a lot closer in spec to each other, just there is that one or 2 oddballs that could throw things off.

But for the 40 or so dollars I have invested for 2 I feel its worth it. Especially since the gear I make for myself I prefer it to have personality that I have to get to know; sometimes I find some real winners that just sound really cool (like using fets in 1176s that don't have the "optimal" curve)

 

[johnnyscotch]

I made some head-way on the T4B front.

Frank has everything you need to make them, right here:
https://sites.google.com/site/diypartsstore/catalog/new-t4b-opto-el-panels

I ordered the parts and I'm going to have a go at rolling my own. It actually looks surprisingly easy, as AbeChap mentioned. There's a little slideshow on the site, it's only a few steps. I'm actually surprised these are so hard to come by, based on the cost and availability of the components.

I'll post here if successful.

 

[ethervalve]

Hi all,
I just realized that my D-La2a is suffering from a bit of cross-talk at high frequencies.
Has anyone else encountered this? Any ideas for troubleshooting? I wonder if running shielded cabled from the board to the Edcor transformers would help? (tried--didn't help) Maybe, lowering the value of C4 (current 330pf)? Lowering the overall gain with that 12ay7 mod?

I do also have the oscillation issue (really a non-issue because it only occurs at freakishly high gain levels).
Thanks in advance for any insights.

 

[django]

having problems with my la2a, it seems to need a pretty epic input signal before it does any compression and the output signal is huge aswell, have to have it below 1 to avoid clipping inputs.

What should r125 be roughly? Would the type of neon have a big effect on it working? (fairly sure i ordered the right type but it was a while ago now so can't remember) Also i have a 33uf for c174, wondered if this would be slowing the compression down at all aswell?

thanks michael