LA2A PCB ver 2.0 build thread

[crisotop]

I've just spotted that sowter sells UTC A10 (Sowter 1009) and UTC A24 (Sowter 1010) replacements - anyone has an idea what they sound like and if they work in a Drip V2 Board?

Thanks!
Christoph

 

[Stagefright13]

I'm using the Sowter transformers in mine and they sound excellent. Read the instruction manual and you will see they are recommended.

 

[crisotop]

Hi John,

Greg recommends 4383 and 8940, which seem like modern versions or so - the model numbers I posted are labelled as remakes of the original UTCs. I was just about to order the ones stated in the manual when I saw the new "old" ones....

thanks
christoph

 

[mrclunk]

christoph, i'm after answers to the same question. I want my pair of La2's to sound/compress as close as possible to the originals (within reason). I'm not using original UTC xforms as i want the ability to stereo link with similar characteristics. I believe new pairs of sowters will be closer matched than random ebay sourced used UTC's.

what i don't understand is the different impedances and ratios and how that effects the circuit e.g
input xforms:-
4383 is 1:4 600/10K http://www.sowter.co.uk/specs/4383.htm
1009 is 1:9 600/50K http://www.sowter.co.uk/specs/1009.htm

or is that just the values used to work out freq response, i.e if u load the 1009, 600/10K it will have the same gain as the 4383???

i'll leave it there, best do some work!

 

[crisotop]

4383 is 1:4 600/10K http://www.sowter.co.uk/specs/4383.htm
1009 is 1:9 600/50K http://www.sowter.co.uk/specs/1009.htm

This is exactly what I don't get as well - but as you said, better do some transformer research, or stick with Greg's recommended combination. Regarding to his statement in the manual, the sowters he is using should perform just fine.

regards
christoph

 

[gerardmanvuca]

hey Drip,
lovin this opto PCB and defin gonna get one as soon as i have the funds....just wondering tho if its possible to build these into a stereo unit? Can i get the matched T4s from u? would i be able to add 4 T4s ..2 with fast attack and 2 with shorter attack and be able to switch between them? like the 2LA2

 

[dave P]

This is how I understand it.

The original Input TX is 1:9 and the output TX is 5:1 so that makes an overall gain of 9/5 which=1.8 times your amps gain of 100.

The DIY Sowters are 1:4 input and 3:1 output so they make an overall gain of 4/3 = 1.33 times your amp gain.

So you will have 1.8/1.33 more gain with the original spec TX's than with the DIY types thats 35% extra or 2.6dB, not a lot in the scheme of things.

I hope thats helpful
best
dave P

 

[CJ]

forget ave P

get original

UTC iron, nothingcan repolce it,

Mag Met sells the ame fucking formula to everybody nowdays, oh, Super Q, it has .99000002 perrcrent cobalt, you will never find a true cobalt transformer anymore, sans the ollinator, buy up UTC on ebay as quick as possible, you will get superior lams, dialtrice matarials, superior craftsmanship, supurior wax complete wt with poly stylenolm what ever, the4e is no turning back, we will never hae ir onr=n like this, it is all down hilll buy the iold lams,



I wuill post metal alloys for varoius vendors, you will be amazed at the diferenr t lams used in the years of the whatever.

Gus was right all along, it's all in the lams.

And now I look into sq lop, super mendur

 

[dave P]

CJ is the man for which iron to use.

I was only interested in the math on the options,

Dave P

 

[CJ]

you need the sound of UTC, I am sorry.
Or else you have a

Sowter La2a

Or a Lundahl LA2a

or a Jensen LA2a

or a BumFuck La2a


but very few people build the Real LA2

HA 100X and A 24, anything else is just an imitation, especially if you use 6SN7 for line amp...
:razz: :grin: :grin: :sad: :shock: :razz:

 

[Stagefright13]

If you have the money Mr. Kulka at studio electronics sells new reproductions for the LA2 also. These are the same that UA uses in the new ones. But trust me you will find the Sowter's sound pretty freakin' great. IMHO.

Drip DOES compare the originals to the Sowter's in the manual soundwise. He said the UTC's are slightly darker. If I wanted darker I can just add a deesser... LOL

However I don't have the old ones to compare to.

 

[dandeurloo]

Has anyone hooked up a sowter power transformer to the Drip board. I have everything other then that and my Sifam meter hooked up. I have the Sowter 0295 s tranformer. Any help would be great. I am pretty new to this stuff and I dont fully understand schemeatics and I don't want to wire something wrong with this much power.


Thaks

 

[Stagefright13]

Fully read the thread and I am pretty sure someone has the Sowter power transformer wiring in here somewhere. But don't try any mains wiring if you are unsure. Be patient and check whole thread. And be SURE of what you are doing!

None of the "I think it goes here". This ain't horse shoes usually where you can get close and live to tell about it. LOL

 

[dandeurloo]

yeah I've read the thread a number of times. The one sowter transformer is for a european build and is a different model transformer. i did order the one that is recommended in the BOM but I haven't seen any info anywhere for how to install it.

I did email Drip and Greg thought that someone here would have the know how since he personally has not used the Sowter power transformer.

Here is a question what volt rating do I want to get out of this transformer 240, 120 or 110V? Then I am pretty sure I willn't be using all of the wires on the transformer. Do I just clip the ones i am not using back and tape them up?

Thanks for any help.

 

[crisotop]

Heyho,

My first unit (of two) is "finished", but I'm having slight troubles. It's compressing fine (good threshold range, VU works), but the output is very low, has no bass and is very distorted once I turn gain past 8 o'clock. I'm using Drips V2 PCB and the suggested Sowter trannies. I'll let the unit rest for now and finish the second first, so I'm able to check if the next is working as it should. Any hints so far?

Thanks!
Christoph

 

[Stagefright13]

You very well might have some other problem but make sure you are using balanced cables in and out. You will lose bass if you use unbalanced cables. Just a suggestion. Good Luck!

 

[crisotop]

thanks! I'm using balanced cables, also tried swapping the tubes in the gain section, vu meter is still not moving in output mode, same sound problem...

cheers
christoph

 

[crisotop]

damnit - my second build behaves in exactly the same way, so it'S definitely my fault and not a broken part :?. To sum things up once again - very low and distorted output signal, low frequency hum, vu not moving in output mode. Gain reduction is working perfectly.

Any hints much apprechiated
thanks, christoph

 

[wmb]

Are you sure you are returning into a balanced input? I had a similar problem when I finished mine. It was because I was returning the signal into my BAE 1272 UNbalanced instrument input. Returning the LA2A output into a balanced input revealed that everything was working fine. User error on my part. I posted about it in this thread.

Good luck, wm

 

[crisotop]

I just double checked, no change, even with different (balanced) cabling straight into the converters

thanks!
christoph