LA2A with 250uA amperemeter, does it work?

Hi,
I'm just collecting parts for a LA2A. I found a very nice 250uA meter and would like to use it for the Limiter. It's not a VU-, just a simple but nice amperemeter. I built for example my 1176s with Sifam VU meters and I realized that I almost never use them for VU Level output. Most of the time it indicates gain reduction. Of course I can't use the 250uA ampere meter as VU meter in the LA2a and the ballistic behaviour won't be as with a VU meter, but my question is, would it work or not. Did anyone built the LA2A with other than VU meters ?
best regards
Bernd

Nope.

Get a real VU. I did it with a 50µA meter, 100µA would be the BARE minimum sensitivity, anything needing more than that is a complete no-go.

I did it once, and I've built dozens of LA-2A's since then... every one after the first has been a real VU... there's a lesson learned in there.

Keith

Hi Keith,
thx a lot for your response. I've almost expected this answer. So I need a real VU meter. What me brought to this idea was, that a VU meter is also around 200uA, afaik, so I thought there might be a chance. So I'll try to get a Sifam or Modutec VU.
Cheers
Bernd

yes indeed, but you fight the ballistics.

Even though the signal is at a fluctuating level, the actual GR is dieplayed as what a VU meter would indicate if the SAME corresponding GR were applied to a constant-level signal. For that reason, it still really needs to have VU ballistics.

I worked hard... for weeks, on and off... and got close-ish... but when I compared it side-by-side to a real VU meter in the second one I built (a bloo), I worked some more and got it a little closer. I used a 50µA movement, and was able to use the increased sensitivity to 'speed up' the meter by way of a few 'cheats', which I wouldn't have been able to do if it were a less sensitive meter such as 250µA or 500µA.

Then I just bought a VU meter and I've never regretted the decision.

If anyone wants to buy a PERFECT looking Teletronix LA-2a meter which reads correctly, but doesn't have quite the perfect ballistics, I might sell this one, but it may still have some value as a "display piece" since it looks exactly right. (It's the original Beede movement as used on the REAL original LA-2a's)

Here it is with an early version of the meter 'conversion' network still external to the meter:

-When I finally got it as close as I could, I put the 'conversion network' inside the meter case, so it looks original.

Here it is next to a UA reissue...


Keith

Keith,
which one is the UA reissue?!? :shock: I'm impressed by your neat wiring. You convinced me not even to try the amperemeters, I'll keep them for some varimu stuff. Actually I'm building a Dual LA2A on pcb designed by silentart. He built a prototype and as a matter of fact, the unit is not only "silent", his pcb- and frontpaneldesign is high "art". Looking forward to use this extraordinary and legendary piece of gear in my music production.
Cheers
Bernd

Yes, I now regret making it so close to the original (with the front panel closed... the "All-Red" wiring is a giveaway internally however!) and since then I've only made blue ones...

-But as an exercise in "full-replica" cloning, there have been a LOT of people who thought it was a real one and have had to be told repeatedly that it's just a darned fine-sounding replica...

Keith