D-LA2A Support Thread

[crisotop]

write me a pm, I might be able to help. The "standard" components (resistors, pots, caps, etc..) aren't hard to find. It's tricky to get the t4bs and suitable tubes (the circuit is a bit picky about the tubes in the amp section).

cheers,
christoph

 

[pacemaker]

Hi Crisotop,
i allready have quite all parts,
just missing the resistors, they all seems to be 1/4w except a few 3w
and diodes, from D3 to D6, wich i haven't identified yet,
also the R125 "TBD" resistor ?

 

[crisotop]

For the Diodes 1-6 I used 1N4007, R125 is roughly 33K (but should be "to be determined" in circuit - I used the suggested 33k value, and my unit works without any noticable problems)

hth, christoph

 

[pacemaker]

Ok perfect,
i was studying at volker schematics and got the answer for D3 to D6,
but was missing the TBD resistor,
can you confirm me resistor wattage ?
cause a saw some partlists for LA2A with 1/2w resistor
I allready have quite all values but only in 1/4w ,

 

[crisotop]

I'm using "modern" 0.6W types - but as far as I recall Volker mostly used 0.25W types - maybe someone else can chime in on this?

christoph

 

[Kingston]

1/4 watt is fine, but it should really be a 50-100k trimmer instead. It's used to fine tune the T4B's. Keith (SSLTech) wrote about it extensively. Search the forum.

33k value was used by default on most original LA2A's, contributing to the "no LA2A sounds the same" myth.

 

[pacemaker]

thank you guys for the advices,
will use a trimpot in place of r125,
Volker if you can confirm that 1/4w resistors are ok,
i couldstart soldering instead of making a new mouser order.
Volker are you here ?
Regards
Francois

 

[bkbirge]

Hey guys, hope this is the right place, apologies if not. I just picked up a completed D-La2a that has silentarts rev 2.0 board in it from a guy in France (I'm in USA). Build looks good and he switched it over for 110v before he shipped. When I turned it on it immediately blew the 0.5a fuses so I replaced 'em with what I had which is 3a and I reseated the tubes. Now it turns on, looks fine (haven't listened yet) and I checked the voltage on the board: the 6v taps read 7v and the 250v taps read 300v, am I going to run into problems running this hot? I don't want to burn out the filaments and my mains voltage is actually higher than 110, more like 120-130v. I didn't see any adjustment on the boards so I assume it's down to having the right transformer. I've asked the seller but I don't think he's the guy who built it. Advice please?

Oh also wanted to ask, I've got Purusha's dual enclosure and on the back are punchouts for a selectable HPF sidechain but I didn't see anyplace on the PCB's, is this a separate board or a feature that was never implemented? It'd be fun to have that.

 

[[silent:arts]]

Volker if you can confirm that 1/4w resistors are ok,
i couldstart soldering instead of making a new mouser order.

except of the 2W resistors I used 1/4W with no problems.

Volker are you here ?

sometimes - have been very busy the last few weeks

 

[[silent:arts]]

Hey guys, hope this is the right place, apologies if not. I just picked up a completed D-La2a that has silentarts rev 2.0 board in it from a guy in France (I'm in USA). Build looks good and he switched it over for 110v before he shipped. When I turned it on it immediately blew the 0.5a fuses ...

0.5A is fine with 230V, but needs to be doubled for 115V. use a 1.0A slow blow.

... the 6v taps read 7v and the 250v taps read 300v, am I going to run into problems running this hot? I don't want to burn out the filaments and my mains voltage is actually higher than 110, more like 120-130v. I didn't see any adjustment on the boards so I assume it's down to having the right transformer.

there is no adjustment, the schematic is exactly like the original. your problem is the non-standard 120-130V mains. you could try some high wattage resistors between the transformer and the PCB, like Kubi did in his D-AOC

Oh also wanted to ask, I've got Purusha's dual enclosure and on the back are punchouts for a selectable HPF sidechain but I didn't see anyplace on the PCB's, is this a separate board or a feature that was never implemented? It'd be fun to have that.

I have never had any plans for such a feature. Might be his standard stereo 3U backplane.

 

[Kingston]

I have never had any plans for such a feature.

you already implemented it...

Oh also wanted to ask, I've got Purusha's dual enclosure and on the back are punchouts for a selectable HPF sidechain but I didn't see anyplace on the PCB's, is this a separate board or a feature that was never implemented? It'd be fun to have that.

That's just the 1meg trimmer/rheostat of the sidechain (R37), right next to C12.

You can play with the values in any way you like, try 0k, 500k and 1meg for starters...

 

[[silent:arts]]

I have never had any plans for such a feature.

you already implemented it...

that wasn't me ;D

 

[bkbirge]

Thanks for the info and advice guys!

 

[pacemaker]

Thank you very much for confirming resistance wattage Volker !
let's solder this beast !

 

[pacemaker]

I am preparing a mouser projet for D-LA2A;
it can helpfull for future builders,
does abyone has a partlist ?
regards,
Francois

 

[[silent:arts]]

Francois,

here you find bernbrues parts-list

 

[pacemaker]

link is not working for me  :'(

 

[bernbrue]

Hi,
here it goes.

http://www.twin-x.com/groupdiy/albums/userpics/Part_List_LA2_rev01_Platinenlayout_Silent_Art.xls

regards
Bernd

 

[pacemaker]

ok guys i got everything,
Frank's forum is not allways reachable for me,
don't know why.....
i was able to save the first page of the D-LA2A thread
wich contains all the info i needed.
Thank very much !!!

 

[Soeren_DK]

Is there any Lundahl trafos there will fit this project?

Cheers
Soren