All things LA2a related

[Bluzzi]

Yes I know its been done and I can create a "clone" as well, but I was wondering if using another material would alter the qualities.

Besides the money ($2.00 for the case, $6.00 for LDRs aprox.) I would suspect that other EL material may work. Wether it works or not is worth the effort to me in order to "see for myself". Isn't that why we are here in this forum, to have fun and end up with something to be proud of?

I think if you count the time and money put into a DIY there is no saving. For me its more for self satisfaction and curiosity. I figure for under $10.00 I can experiment. I will be eventually getting the EL from LSI as well.

I wanted to see if others had built some without the original material and gotten usefull results.

Jim

 

[JerryPbury]

Tubes are in so is T4B. Nothing is hot or smoking or popping. I'm going to pass a signal through it tonight. See what happen's.

 

[Scenaria]

my mistake...

if you want to experiment with other light sources then by all means have fun.. I thought by reading your question you were asking if there was a cheaper/better aternative..


jerry... be sure to turn the two pots on the back fully counter clockwise

 

[rafafredd]

Well, CJ talked about a new T4 he built some time ago from all Radio-Shack parts. He said it was the best sounding he had...

 

[JerryPbury]

It seems all high voltages are turrets connected to the 6AQ5A. I used Cayocosta's 1968 layout. There is no connection on pin 1 shown (and no reference in the instructions as to a link between pin # 1 & 7). However all of the other schematics that I have (at least 3) show a link between pin # 1 & 7 on V4. So it looks like I need to link these. More later.

Jerry

 

[Scenaria]

linking 1 & 7 isnt necessary.. but you can if you want..

if your voltages are off make sure that R34 R29 and R36 are from the same schematic...

either 470 and 10k/2w or 1k and a 22k/2w

if you get these mixed up your voltages will be off..

 

[Bluzzi]

Yes I think I read that somewhere about CJ's T4B. II think he used an alarm clock's EL material. I have some EL material to try from a night light but I welcome any other sources of alternatives.

The whole thing is that ithe T4B also changes the LA2A's attack and release so some T4B designs may be good for drums while others maybe better for vocals etc.

I am speaking not from personal experience but from readings. After I buid 2 LA2A's I'll start experimenting with T4B's and interchanging them to compare. Same with transformers. I'll be using the Sowters but I would like to hear the Jensen and Lundhal ones as well.

Jim

 

[JerryPbury]

Steve,

This is what I have.

R29 4.7K / 2 Watt
R34 10k / 2 Watt
R36 470 ohm

It's just the voltages that are connecting to V4 @ pin 2, 5 & 6 (and affected connections).

Actual: Should be:
B21 370v 360v +10v
A21 330v 275v +55v
A20 328v 131v +197v!
A19 323v 105v +218v!
A16 47v 7v +40v

Checked all of my connections and component values. All appear OK. I know it's something dumb but I sure haven't been able to track it down. All other voltages are right on the money including heaters. I have switched every tube and still get exactly the same results. I'm baffled.

Thanks,

Jerry

 

[Scenaria]

did you turn the two pots on the back fully counter clockwise?

 

[Scenaria]

whats your B+ voltage?

and are you sure that you have a 4.7K in there and not a 47k for R29?

 

[JerryPbury]

Steve,

B+ 330v

4.7k

CCW (doesn't make any difference in voltage readings).

Thanks,

Jerry

 

[cannikin]

steve;

I'm hooking up the Allied Power Trannie and just want to confirm my connections:

Primary:

1 Black to Live on power connector (Wire to B24 then to B25)
1 Black to Neutral

Secondary:

Center Tap 6.3v (green w/yellow stripe) to ground Bus/TAG 3
Center Tap 250v (red w/yellow stripe) to ground bus/TAG 3

2 - 6.3v (green) to A24 & A25 with heater Wire.
2 - 250v (red) to A22 & A23

Ground:

Grey to Gound on the Power Connector.

Thanks.
David

 

[QNote]

For a DIY EL panel, try this vendor...

www.mpja.com

They carry an EL panel that is only $2.25. It is larger than what is needed for a T4B, though. But, if you use a larger housing, I think it would work great. I didn't see any LDR's, though. Sorry.

Later,

 

[Scenaria]

[quote author="cannikin"]steve;

I'm hooking up the Allied Power Trannie and just want to confirm my connections:

Primary:

1 Black to Live on power connector (Wire to B24 then to B25)
1 Black to Neutral

Secondary:

Center Tap 6.3v (green w/yellow stripe) to ground Bus/TAG 3
Center Tap 250v (red w/yellow stripe) to ground bus/TAG 3

2 - 6.3v (green) to A24 & A25 with heater Wire.
2 - 250v (red) to A22 & A23

Ground:

Grey to Gound on the Power Connector.

Thanks.
David[/quote]

yep.. sounds good

 

[Bluzzi]

[quote author="QNote"]For a DIY EL panel, try this vendor...

www.mpja.com

They carry an EL panel that is only $2.25. It is larger than what is needed for a T4B, though. But, if you use a larger housing, I think it would work great. I didn't see any LDR's, though. Sorry.

Later,[/quote]

Thanks Prentice,

I'll try one to see if it works (I don't know if 400HZ will cause a problem).
There are nightlites available here locally and I have a few of those so I will be canibalizing those as well. The LDRs I have sources for and are an easier item.

Jim

 

[cannikin]

Hey Guys

I'm still a little lost when it comes to wiring the sowter input trannie.

Input:

just leave the pink one untied (cap it with some heat shrink) - DONE
Black to ground - DONE
brown and green from the input XLR - DONE (Green to XLR 2 Brown to XLR 3)

Here is my point of being lost on the input:
blue and grey are the outputs. Do I wire a 68K resistor to each wire? then from there is connects to...?
Also R7 (2.7K)?

My next confusion:

put a couple of 1k resistors on the grids of the 12BH7A this will help stabalize that tube. Grids?

 

[JerryPbury]

Sowter has a schematic on thier web site for hookup of the LA2A.

http://www.sowter.co.uk/

Look under Pro Vintage LA2A.

Jerry

 

[cannikin]

[quote author="JerryPbury"]Sowter has a schematic on thier web site for hookup for the LA2A.[/quote]

Thanks I've been looking at that thing for a couple of days, and the answer has eluded me.. Oh did I mention I suck at reading schematics?

 

[Scenaria]

I'll try and help ya when I get home...

im falling behind as im litteraly dealing with an average of 50-60 emails every couple of days

 

[JerryPbury]

[quote author="JerryPbury"]This is what I have.

R29 4.7K / 2 Watt
R34 10k / 2 Watt
R36 470 ohm

It's just the voltages that are connecting to V4 @ pin 2, 5 & 6 (and affected connections).

Actual:---------Should be:
B21 370v------360v___+10v
A21 330v------275v___+55v
A20 328v------131v___+197v!
A19 323v------105v___+218v!
A16 47v--------7v_____+40v

Checked all of my connections and component values. All appear OK. I know it's something dumb but I sure haven't been able to track it down. All other voltages are right on the money including heaters. I have switched every tube and still get exactly the same results. I'm baffled.

Thanks,

Jerry[/quote]

Thought I would bring this up again as I have not found a cause/solution for the high voltages on V4. Any suggestions? I have checked every component, connection and layout several times over with no change.