[Berndt]

My luxman m-430 integrated has pre out and main in jacks.
I am assuming these jacks will allow me to bypass either the pre or the amp?
When I get paid tomorrow I am finishing payment for me mapletree ultra 4 se pre amp.
My real amp is still about a month off. Can I plug my new pre into the main in jacks?
Thanks, Bill

[Berndt]

btw, I have the manual and it does not say shit.
I also just tried putting an input directly to main in (olive media player).
No combination of panel buttons made sound.
There is a sheilded switch on the back panel labeled signal processing. It is locked in the off position.
Could there be an internal jumper I have to remove to decouple the pre?
Under the main in jacks is a label, 200mv.

[Bob Reynolds]

Typically, there are a pair of jumpers between the preamp out and the main amp in jacks. That's what I've seen on Bryston, NAD, Creek and Rega. Can you post a pic?

[srb]

It sounds like the "signal processing" switch on the panel might take the place of jumpers?

In the "Off" position, the pre-out and main-in are connected, and in the "On" position they are not, allowing you to insert a "signal processor" between them, or use the preamp and amp independently.

I am only guessing.  Hard to belive there is a switch on the back panel that the manual does not address.

[Helge Gundersen]

My Roksan Caspian M has pre out and power in. The manual states that the power-amp input "requires internal work to be activated". I don't know if it's the case with your integrated, though.

By the way, if anyone knows if the "internal work" on the Caspian is something that can be easily done by myself (no soldering or stuff like that), I'd like to know.

[Bob Reynolds]

In the "Off" position, the pre-out and main-in are connected, and in the "On" position they are not, allowing you to insert a "signal processor" between them, or use the preamp and amp independently.

Sounds plausible. You could use an AC voltmeter to check for the preamp being active with the switch turned "ON".

The 200mV label for the Main In jacks is a concern. Does it imply input sensitivity or max input?

[James Romeyn]

Yes...the switching is very unintuitive, but my analysis per your descriptions:

The "signal processing" switch is one DPST, taking the place of what is usually a pair of outboard jumpers; often external jumpers short only the positive signal (U-shaped hard-formed single-conductors) while the grounds are permanently shorted internally.  The double poles of the switch are the two L/R channels; the single-throw positions are:

"Off" = pre-out is shorted to power-in.  In this case no outboard signal processing component is employed, the integrated functions normally. 

"On" = pre-out & power-in switch is open.  This allows any type line-level "signal processing" to be employed at that part of the signal path: An EQ can go in-line in the circuit, the internal preamp can function w/ one or more outboard amps (the internal power amp can be one of the two amps employed), an outboard preamp can function w/ the internal power amp (per your desire), etc...

"200mV" is the power-amp input level required for full power output into an 8-Ohm speaker load, indicating a moderate to high-moderate input sensitivity. 
 
I'd bet lunch money this is correct. 

[Berndt]

Thanks for everyones help.
Is there a suggested way to check if the main in imput works with a DMM first, or should I just put a source on it?
Next question, when you can adjust gain on a source ie cd player or my olive, is there a prefered gain you use?
Should I run the media player 100% and tone it down with the pre?
Thanks for your thoughts...

[James Romeyn]

...check if the main input works with a DMM first, or should I just put a source on it?...

Turn signal processor switch on.  IF the speaker's maximum power rating is equal to or a bit greater than the amplifier power rating, you can do the finger test: Plug an interconnect into the alleged power amp input.  VERY BRIEFLY touch a finger only to the signal pin on the open interconnect end RCA plug.  Simultaneously don't touch or barely touch the ground/shield collar.  You should hear a distinct buzz from the speakers, the sound of the amplifeir multiplying the antenna signal which is your body.  The greater you short the input, by touching the RCA ground collar, the quieter will be the buzz.  The quieter the buzz the less chance of speaker damage.  But if you totally short the RCA, no or little buzz.         

when you can adjust gain on a source ie cd player or my olive, is there a prefered gain you use?  Should I run the media player 100% and tone it down with the pre?

Very good question.  I believe the best relationship between any music signal source voltage & load would be when the largest voltage swing of the source is just below the overload point of the load.  In theory this is hard to determine because even software varies in maximum voltage.

For your purpose, there are other variables.  Your system has two variable level controls, one in the source & one in a preamp.  It may well be best to effectively remove one pot by leaving it set at maximum clockwise (even better might be to get inside & short across the #1 & 2 pins of the pot).  If the pot is at some midpoint, the signal may be degraded going through a variable resistor.  Also, possibly some digital level controls produce less bits & lower resolution the lower the output setting.  I'd experiment first by leaving the source at max, & see if you hear any distortion indicating the load is being overdriven.  If not, & you probably won't, that would appear best.  Potentially one level control may be significantly higher in quality than the other.  In that case it would be best to leave the lower quality control at maximum. 

Every accessible electrical contact including control contacts should be cleaned/treated w Caig ProGold cleaner.  Some/many pots are not sealed & have an access opening on the rear cover.  

Experiment. 

[James Romeyn]

In the "Off" position, the pre-out and main-in are connected, and in the "On" position they are not, allowing you to insert a "signal processor" between them, or use the preamp and amp independently.

Sounds plausible. You could use an AC voltmeter to check for the preamp being active with the switch turned "ON".

The 200mV label for the Main In jacks is a concern. Does it imply input sensitivity or max input?

200mV is a reasonable overload point for a MM phono input but not a line input.  Home audio has no concrete standards in this area.  In Pro Sound .707 V input normally equals 1W @ 8-Ohms.  Home audio is usually in the pro-sound ballpark, so a 200mV line-level overload would be unacceptably low.  1 to 5 V is an average range, sometimes as high as 10 V.         

[Berndt]

both tape inputs have the same 200mv label as well as the DAD/tuner input.
I am just a bit tenative about experimenting with my newly modded speakers, as the fuses have been removed and my modder cautioned me that any serious clipping will kill the tweeter wires.
Time to pull out the fr125's!
I can't wait to finally hear tubes in my system again.
I'll start out with the olive 100%, and just throttle with the pre.

[Bob Reynolds]

Thanks for everyones help.
Is there a suggested way to check if the main in imput works with a DMM first, or should I just put a source on it?
Next question, when you can adjust gain on a source ie cd player or my olive, is there a prefered gain you use?
Should I run the media player 100% and tone it down with the pre?
Thanks for your thoughts...

You can download a -20dBFS sine wave @ 1KHz signal from the M&K pro site. Use that as your source signal. With that playing, use the DMM to measure the voltage output from your source. Assuming your source is close to the 2V Redbook for 0dBFS, then you should measure a voltage around 0.2 volts when the -20dBFS signal is playing. That's close to the 200mV label on your amp, so I'm not sure I would connect it. But, it's your call. If you do connect the source playing the -20dbFS signal, you can then measure the voltage across the left (assuming you downloaded the left channel signal) speaker posts. If you get a voltage, it should be larger as determined by the amp's gain, then you know the main amp jacks are working. This way you protect your speakers.

As stated I think it makes sense to use the preamp to attenuate the signal.

Good luck,
Bob