LHX2 ( JCM800 sim ) photo's

[MartyMart]

Finally boxed, not too pretty but functional !!
Quite a large box, 7cm X 13cm X4cm
Great sounding amp sim BTW

MM.
Outsides :
http://www.pbase.com/image/62530244
http://www.pbase.com/image/62530259
http://www.pbase.com/image/62530265
Guts :
http://www.pbase.com/image/62530275

[donald stringer]

Hey marty I got mine finished this past weekend. I personally like to allow myself a lot of room, so my stuff gets kind of big. But I am going to get a picture up pretty soon. Like you said a very nice sounding amp sym and congratulations. Now on to the fender sym. Wow you managed to  get a lot into a seemingly small space. The secret for me  to getting through this build succesfully is to build one stage  per night and sound check it. To me this is not a stompbox build but more of a pre-amp and that is the look I am going for.

[MartyMart]

Yeah, for 9 opamps, I thought that I kept it quite small !!
It's great but lacking some low end really, I didn't manage to solve that small problem.
I have the Bass pot at "11" permanently ...
I agree that this is probably more suited to a rack, I have two projects on paper :
One is a nice "Cornich" style pedal board and one is a "Jfet amp sim rack"
I'm thinking of putting 5 sims in a single 19 inch rack, probably the Classic 30, Bassman,
18, Citrus Graphic and Dr Boogie.

MM.

[jmusser]

Nice work Marty! The insides look nice and clean too.

[Doug_H]

It's great but lacking some low end really, I didn't manage to solve that small problem.
I have the Bass pot at "11" permanently ...

Marty, did you check his latest schem? http://home3.netcarrier.com/~lxh2/marsh.html

He mentions the "chunk" (low freq boost?) and "damping" controls and how they add some bottom when plugged into an amp. He also included a freq plot that show how they affect the sound.

Doug

[MartyMart]

No, didnt see that !!!
I guess that would solve the problem then ....
I've stuck my Boss PQ4 eq after it and can get enough bass back, so I wont
"rip it up" as I've just boxed it

Thanks,

Marty.

[donald stringer]

I am trying to wrap my mind around the plurality of filters. Do you just reproduce c1 c2 r1 r2 and 1op-amp for as many filters as you want to put in line with the dip? I wish that part were a little clearer.

[Doug_H]

There's a "filter data table" at the bottom of the page. Each column represents another filter stage with the respective component values you need for that stage. Looks like 13 stages of filtering- yikes!! There are 5 "dips" in parallel with ea other, and 8 "peaks" in parallel with ea other. Plug the dips and peaks into the appropriate dashed box he shows in the schematic.

Doug

[MartyMart]

I didn't go as far as the `"speaker sim" section .... way too many opamps IMO !!
I'm very happy with it into amp or Condor/Simple Marshall sim.
If I built another, I would include the extra "Bass" and "Chunk" sections though ..

MM.

[Doug_H]

I didn't go as far as the `"speaker sim" section .... way too many opamps IMO !!
I'm very happy with it into amp or Condor/Simple Marshall sim.

I agree that the speaker sim could probably be vastly simplified. I suspect he was trying to match a freq resp curve he measured from a 4x12 cab. Elsewhere on his site (he used to) have a description of how he measured the speaker response. If he did it in an anechoic chamber it may not be a "real world" response. OTOH, if he did it in a room, the response may include artifacts of the room resonance which may not match your room, etc, etc. There is also the issue of the test equipment itself and what effect it may have had on the outcome.

IMO, in the end, when it comes to speaker simulation- how much is "enough" is a subjective judgement call that only you can make yourself. FWIW, here's a "lite" version of the "fender cab" LXH2 speaker sim: http://www.generalguitargadgets.com/diagrams/lxhlsc.gif

Doug

[donald stringer]

This is my lxh2 marshall sym [first part of my formerly known as red green box] now it looks like its turned into a red green stack. Here are some pictures.   http://smg.photobucket.com/albums/v172/troublerat/                                                                         I am                   seriously going to have to think about that next build. No doubt it will sound as robust as the marshal sym. But once I start I will have to finish it.

[MartyMart]

That's a beautiful polished rack case Donald !  Nice sloping pedal board also, the "diamond tread" looks great

MM.

[krille2]

Nice to see that you built that thing, Marty! Regarding the cab sim there's some info on:
http://www.amptone.com/lxh2ampsimulator.htm
AFAIK the LXH2 cabsim follows a typical g12h speaker curve in a sealed box. Don't know if it's a plot from an anechoic chamber though. Anyway, I built the whole thing quite some time ago and it is REALLY good. At the time of writing I have a little project to simplify the cabsim section, the goal is to keep the freq response somewhat omplete but with a lot fewer components. If time permits I might publish it on my website... http://hem.passagen.se/amps

Regarding bass, you could look at the 0.01 uF just before the clipper diodes, maybr a 0.1uF will do better? And speakinng of bass, try to raise the initial 3000pF cap to 4700pF or higher to more excatly sim the real thing!

/Krister

[wampcat1]

Marty,
could I talk you into posting one of your soundclips with it? 
bw

[RollingElbow]

Lets ressurect this topic as well! Soundclips would be cool.. interesting to see how the various incarnations of this LXH2 sound. I was going to try the preamp and then simplify the cab sim portion due to cost restrictions. What I am trying to determine, is which one would sound best for direct recording:

1. LXH2 + simplified marshall cab sim / or fender for that matter
2. JCM 800 + marshall cab sim
3. thunderchief + marshall cab sim

decisions, decisions, decisions....

[krille2]

I've made a really simple cabsim if you're interested. Could be found at: http://hem.passagen.se/amps

Defenitely would love to hear more LXH2 incarnations as well! Post clips for our longing ears 

[Connoisseur of Distortion]

i made one of these, but it feedbacks insanely, and the tone controls aren't as useful as i'd like. i was pretty surprised by the gain on tap.

might have to go back after it...

[phazerz]

Marty, where did you find the vero layout please ?

[MartyMart]

Marty, where did you find the vero layout please ?

Made my own "on the fly"
It's a beast of a circuit and I just have not had time to draw that up !!

MM.

[markm]

WOW!
That was a pretty ambitious project huh Marty??
Nice work,
   MarkM