D-LA2A Support Thread

[[silent:arts]]

But it is possible to steal some voltage from the heaters secondary to do this right? running the relays at 5v ? or i can use a second toroid (have lots of 10va anteks lying around).

I wouldn't feel comfortable with AC heaters and a rectifier / voltage regulator next to it (but what do I know) :
a second transformer would do the job for sure (but you won't need 10VA)
you could wire a switch instead of the realays.
you could skip the "In" (or bypass) and solder bridges at the relays too.
many ways ...

 

[Kingston]

I will probably do DC heaters, and steal 5V from there with a L7805.

 

[Silvas]

Thanks for the replies guys, surely i´ll try many ways to do it and see which is best.

 

[stitch-o]

Its Alive!!  (almost)

Just finished wiring up the transformers (UTC A-10 and A-24) and the XLR I/O.
T4B's from Drip and a tasty assortment of NOS vintage tubes complete the circuits 'flavors'.

I've only done power-up so far but will be doing some troubleshooting and more testing in the next few days. Nothing smoked, everything lights up...phew!
I think I might have wired the gain pots backward as when I switch the VU from G.R. to Level, the needles on both VU's pin all the way...until I turn the gain ALL the way up and then the needles fall all the way down.
Also, I plan on dropping in a couple of LED indicators for the IN/BYPASS as I like to be able to see basically whats going on (or off, as the case may be) from across the room.
BIG ups to Geoff004 for double checking my wiring mess and (of course) Volker aka [Silent:arts] for the boards...there were a couple others who helped early on too but names are escaping me (someone gave me a great relay wiring tip)
Anyways, I thought a few pics might inspire some to get to work, round these parts:::
Cheers!

 

[FerrariT]

Is everyone using the custom Xfrmrs [silentarts] had made
or
???

just curious ...

 

[stitch-o]

I re-wired the gain and PR pots: yup, they were wired backwards.
Now everything seems to work on first glance.

The only thing I have noticed now,
when I turn the gain pot up past 65 (2 o'clock) when the meter is on 'level', the meter
jumps up and pins. This happens on both channels and, surprisingly, will happen on both meters
when only one gain pot is cranked and the other gain sits anywhere near 65.
Some sort of feedback maybe but its registering in both channels....hmmmm

Still haven't gotten' it on the bench to pass audio, measure voltage, and calibrate and such but that should happen tonight.

Cheers!

 

[rob_gould]

Hi [silent-arts],

I want to use Elma 24 position rotary switches for gain and peak reduction.  Is it just a simple case of calculating 0 - 100k log values and 0 - 25k log values on a spreadsheet and picking the nearest values like you did for the PM 660?

Thanks,

Rob

 

[tskguy]

Hey all,


What is ds101 and ds201 it says NE2 under the Semicunducter. I cant figure out what it is..
Any help would be great!!
Eric

 

[RedNoise]

Ne2 are Neon lamps , avaible @ conrad IIRC.

.:EDIT:.

http://www1.conrad.de/scripts/wgate/zcop_b2c/~flN0YXRlPTE3MzQwMDEwNDc=?~template=PCAT_AREA_S_BROWSE&glb_user_js=Y&shop=B2C&zhmmh_lfo=&zhmmh_area_kz=&product_show_id=725200&gvlon=&p_init_ipc=X&p_page_to_display=fromoutside&~cookies=1&cookie_n[1]=b2c_insert&cookie_v[1]=62&cookie_d[1]=&cookie_p[1]=%2f&cookie_e[1]=Mon%2c+27-Apr-2009+22%3a36%3a36+GMT&scrwidth=1280

 

[[silent:arts]]

I want to use Elma 24 position rotary switches for gain and peak reduction.  Is it just a simple case of calculating 0 - 100k log values and 0 - 25k log values on a spreadsheet and picking the nearest values like you did for the PM 660?

me too  ;D ;D ;D
on my second one, but no time to build it :-[ :-[ :-[
(will have Haufe 1:1 iron at the input, V74 iron for the output, Drips "Mastering T4Bs") ;D ;D ;D
the PM spreadsheet will work, yes

What is ds101 and ds201 it says NE2 under the Semicunducter. I cant figure out what it is..

yes, what RedNoise said: neon lamps.
it was hard to figure out what to use in europe, since NE2 is an american part number ...

 

[tskguy]

Very cool!! 
Thanks guys,

P.S. I should have a US friendly BOM with Digikey and Mouser part numbers for most all parts very soon.

Eric

 

[geoff004]

What is ds101 and ds201 it says NE2 under the Semicunducter. I cant figure out what it is..

here's a mouser # for the neon:  36NE002

For the power I think there are a couple options.  I used the transformer from Antek and it was pretty cheap - like $30 shipped.  It'll power the whole thing fine.
There's a ton of information at the nrgrecording site - enough to complete this project.

Congrats Stitch - looks great.
I use mine every time my DAW puts out audio.

 

[stitch-o]

thanks bro! Like I said, I owe you a pint or three  ;D

So, I finally passed audio through this sucker and here's my troubleshooting list:
-Ridiculous amounts of gain. I matched levels with bypass and I had the gain knob not even on 1.
I have some 12AU7's around here so I'll try those first and the 22K log w/75k resistor in series trick second.
-Left channel doesn't compress. Also, I'm not sure the stereo link does anything yet either...probably a connected issue.
-There is some distortion and LF loss somewhere. Very well might be connected to the extensive gain issue.

edit: it just struck me that, quite possibly, the relay on the left channel is not getting any power.
That would explain the problem...I'll check that out first.

Once I sort out these little blips, I'll throw it on my friends bench.

Any tips for calibration?

Cheers!

 

[creal]

since more and more people will build the [silent:arts] D-LA2A version I thought I will start this thread.
please ask your questions here, no PMs please.

thx for this thread
i will start mine soon

 

[kazper]

Thanks,

I was wondering about the input iron also. Im considering using Lundhal transformers and Talked with Kevin the US distribitor and he suggested using 1:1 on the input as well.
Im working on a USA Bom and noticed I cant find the silver Mica caps. Does anybody have a usa source for those?

Eric

Mouser
Tubedepot (also a good spot for the big 10uf's)
Small bear electronics

 

[phatmateo]

Thanks for the US BOM!  Good to know someone else is out there in Chicago with a diy addiction

 

[tskguy]

Your welcome,


We should try and get a bunch of the Chicago guys together some time. Its always fun to meet guys that share the same obsession!
Ive met with Shabtek before he is in chi town as well.

Eric

 

[tskguy]

Hi all,

Im trying to decide what type of transformers to use and to save money I think I may try the edcore transformer for output. Ive looked at there web site and with my limited knowledge cant figure out what one would be best. Anyone have an idea what to use?

Eric

 

[deuce42]

This may be obvious but my experience is that the input transformers in these comps have profound effects on sound but output transformers don't seem to me to make the same degree of difference. Others here with far more knowledge than me may disagree and that is cool - we all have views on things.

I would maybe look at the Edcor WSM15k/600 for outputs. They're super cheap (approx $10). You can try the XSM15k/600 instead but the extra wattage that the XSM series give over the WSM series may not really be needed for this project.

Input transformers are another story - I am sure each reputable transformer (sowter, cinemag, jensen, actual UTC's etc) will give the DLA2A a completely different flavour.

 

[RedNoise]

Hi ,
Do you think UTC A25 would work fine in the DLA2A???
IIRC they're 15K/600 correct???
thanks.