Upgrading a Lexicon Alex - schem?

[arbor]

I got a Lexicon Alex for cheap, and would like to upgrade it.

In particular, I'm looking to reduce the noise, and provide as extended a frequency response as possible. I'm thinking the reverbs should be good, but they probably cheaped out on components to get the price down.

I found the service manual and schematic pretty easily by searching the web for:

> lexicon alex service manual filetype:pdf

Unfortunately, none of the manuals seems to have the schematic in it, so I'm trying to pull together a picture based on tracing some of it out.

Given the age of the unit, a recap of the electrolytics is probably in order, so I figure I'll start there.

Electrolytics (all 85-degree):
- C29 - 3300uF 16V, Nichicon VX(M) series - this is for the +5V digital supply
- C39,41 - 1000uF 25V, VX(M) - these are for the +/- 5V analog supplies
- C47,48 - 22uF 16V, VX(M) - these seem to be PS filter caps for the analog side
- C17,20,21 - 2.2uF 50V, VX(M)
- C55,58,63,82,83 - 10uF 35V non-polarized (service manual says 25V) - I can't tell the brand, but it has "9432" marked on it

Should I consider increasing the size of any of those, and/or bypassing them with a smaller film cap?

We'll start here, and then move on to questions about the other capacitors (lots of ceramics around the jacks), the 5% resistors, the LM353N dual op amps (JFET), the MC33078P dual op amps, the 2N3904 or 2N4403 transistors, the linear voltage regulators, etc.

Thanks in advance for your input!

[Jim Williams]

Those are modified here, I also own one. I replace digital conversion parts, sample and hold opamps, timing caps, the demultiplexer with w 74HS types, the comparitor with NOS LF211. Those will lower noise and smooth out the reverb tails nicely. It's difficult work requiring skill and troubleshooting chops. The rest won't make any difference so you would be wasting parts shotgunning out audio path parts or psu parts.

[arbor]

Thanks, Jim! Good to know -- I will chase other projects, then.

After your mods to the Alex, how does it stack up to, say, a modded PCM-70 or MPX-100? I own both, and am wondering where I'd get the best results having you work on them.

Or, would I be better served getting an LXP- or PCM-series and having those upgraded?

NOTE: I'm primarily interested in the reverbs; the multi-fx are a bonus.

Thanks!

[Jim Williams]

The Alex has unique software. It has a gold foil plate program. These are not found in their other products. I use it with a pair of modified Reflex's, a couple of MPX100's used for delays, an LXP-15 and the Bricasti M7.

The Reflex is used almost exclusivly for drums, it's a fat box. It allows for editing and storing as well.

[arbor]

That makes sense. Choices, choices.

Thanks again, Jim.