D-LA2A Support Thread

[AMaziad]

Horvitz, what power transformers are you using in your build?  I'm about to order my parts finally, and that is just about the last thing I need to source.

Thanks,

Ali

 

[horvitz]

Ali,

That's the Antek AS-1T250.  On the small one, I'm not home right now so I don't have my notes but it's the smallest Triad 15V (I think) I could find.. just do a search on Mouser.  You can see on the previous page that I built that out 12V rather than 5V, so if you're doing 5V this will not be appropriate for you.  Good luck!

  Brian

 

[poctop]

Here it is fully calibrated unit 100% functionnal thanks to silent arts,

Please Note than when performing stereo clibration unit on the right is the master unit, so peak red on left side is off,

Cheers ears,  i tought i attached all my testing so far with the unit,

Sincerly
Dan,

 

[poctop]

1

 

[poctop]

2

 

[poctop]

3

 

[poctop]

4

 

[poctop]

5

 

[poctop]

Hi All,

Now here a little explanation the title of the picture is wrong,  the 2 first picture represent the response under no compression but the unit is in operation mode,  we notice i slight bump in the high for the 2 channel,  Channel 2 has a slighlty more accentuous high, the only diffence is that C4 C14 are 390pf maybe a bit too much but this is for a test purpose,  the channel 1 has slighlt less high end    c4 c14 are 240pf so this will have to be tweaked,
The last two picture are the compression 100% curve before and after the limiter response adjustments you can notice how the high is flatter after the adjustments,

Well this is it maybe it is time to enjoy the baby now,

Sincerly Dan,
hope this helps,

 

[poctop]

Channel 2 example

 

[poctop]

Channel 1 example 240pf

 

[poctop]

just to mention Those curves were produce with DLa2A with Jensen in and out,
regards,
Dany,

 

[poctop]

a quick suggestions for any lighting solution with the 5V make sure your heatsink is big enough with this guy get about 45degC on the chip i installed a small one first and changed my mind.

Dany,

 

[[silent:arts]]

Aaahhh, I love seeing new finished D-LA2As  ;D ;D ;D

Mr. horvitz, you did a very nice and clean job, congratulations.
The design fits perfectly to the PM670 friend, you found your own design

Mr. poctop,
thanks for your tips and observations. I added a link in the first post.
Nice and neat job too!
BUT I'm missing a unique poctop front panel

now, keep them coming  ;D ;D ;D

 

[electrisizer]

just to mention Those curves were produce with DLa2A with Jensen in and out,
regards,
Dany,

hi poctop,
are this 10k:10k jensen?

have you done the jensen mod?

http://www.jensen-transformers.com/as/as091.pdf

 

[poctop]

No Just the zobel 11K mod,  my board was already stuffed when i saw that apps, any feedback as if the full mod is worthed now,  only 3 Resistor and 1 extra cap,  i felt that i did want to set my mallory cap at 30$ for the one i received form jensen a 22uf 450,  i dont know my top end positive slope is caused by that or my c4 that not where it should be,  i will try C4 first and do some more sweeps.

Kepp ya posted,

 

[poctop]

Problem with that wierd top end with Jensen Solved tweaked C4 to obtain this flat curve for the makup gain circuit,
1) final picture gain response
2) final picture gain reduction response

finally a value of c14 300pf and C4 = 100pf did the trick for the jensen out,

cheers,
2 picture in the next post,

 

[poctop]

Gain Reduction response,

 

[poctop]

Thanks to everyone,

...............Next Project...............................................
Dan,

 

[Randyman...]

Hello,

Sorry to keep bombarding the forum with troubleshooting inquiries - but does anyone have any more generous "hand-outs" for me on my below issues?

Bump for any tips on my above issue (CH2 passes audio, but no GR).  I know the CH2 Sidechain is getting audio because CH1 responds to CH2's Gain Reduction when "Stereo Linked".  CH2 just doesn't do any GR, and sounds a little distorted when I crank the Peak Reduction control.

Tubes and T4B's were swapped between channels and the problem remained on CH2.  I'm a bit hesitant to start poking around with the unit powered on - so I'd LOVE to get a shove in the right direction before I go poking around the 250V hazards that lurk inside...

Thanks so much!  8)

Randy:
- check if RV203 & RV213 are fully open
- look for bad solder joints at V201, C211, T4B

Hello again,

I checked RV203 & RV237 (I don't see a RV213), and they seem OK.  Adjusting them has no impact on CH2's lack of GR.  Solder joints look good at the other points mentioned as far as I can tell.

Any thing else I can try? 

Thanks for all of the gracious people's efforts that made this wonderful project possible.  I'll post pics as soon as it's 100% working (I think it looks great )...  I've got plenty of other projects to keep me busy for months (5 more compressors waiting on assembly  ;D ), but I'd really like to get this nipped in the bud before moving on...

8)