[PLMONROE]

After modificaation to use active biamping on the RM-40s with a marachand electronic crossover should the switch on the rear of the speakers be kept in the up or down position? Or does it matter? Apart from my trying to follow instructions I guess I don't  understand what  this switch really does.  Thanks

Paul

[ekovalsky]

The toggle switch acts as a internal jumper between the bass and mid/treble binding posts when engaged, which I think is the "up" position.    This allows the speaker to be driven with a single standard speaker cable.

Since you are actively bi-amping, you definitely want the switch disengaged, i.e. in the "down" position.  This decouples the bass and mid/treble binding posts so each receives a separate signal.  You would also do this if you were biwiring with two standard speaker cables or a single "biwire" cable (i.e. 2 spades on amp end, 4 spades on speaker end).

Consult the manual to confirm the switch positions as I could have it backwards.

Others here have reported sonic improvement when an external cable jumper is used rather than the switcheable internal jumper.  At least one dealer recommends deleting the toggle switch for improved sonics, which I did with my RM-40's, and the current VMPS models may not have it at all.  I know the RM/X is built without it.

By the way, did you compare active biamping with the Marchand crossover with passive biamping?  Each has its advantages and disadvantages -- steeper slopes and better efficiency with the active, simpler signal path and less expense with the passive.  I've chosen the passive route with the RM/X.  But Brian added an extra pair of binding posts which bypass the high pass filter of the woofers, thus giving me the option for active biamping in the future without performing surgery on the crossover.

[ctviggen]

If you're using the JR amp, how would you biamp?  Another JR amp?  I have the #10 JR and some people have said that it might not have enough power for the RM40s (and I'm still leaning toward the RM40s as opposed to the RM30s).  But I'd hate to spend (actually, I need a better preamp more than an amp) the money to get another JR, even though I think that my amp is one of the best I've heard on my equipment.  If you don't do that, though, how do you level adjust two different amps?

[ekovalsky]

Model 302/4 has a 2-channel input, 4-channel output orientation. This configuration will allow for a passive stereo biamplification system to be set up with each pair of loudspeaker binding posts connected to it’s own separate channel of amplification to actively and independently power both the high and low frequency drivers or to power a pair of loudspeakers and a separate pair of passive subwoofers from within a solitary single-chassis amplifier.

[JoshK]

Model 302/4 has a 2-channel input, 4-channel output orientation. This configuration will allow for an active stereo biamplification system to be set up with each pair of loudspeaker binding posts connected to it’s own separate channel of amplification to actively and independently power both the high and low frequency drivers or to power a pair of loudspeakers and a separate pair of passive subwoofers from within a solitary single-chassis amplifier.

Not to throw a wrench in the works, or to be a prick, but technically this is passive biamping, not active biamping.

[ekovalsky]

[Not to throw a wrench in the works, or to be a prick, but technically this is passive biamping, not active biamping.

You are correct, that is at typo (in the JRDG 300 series white paper, from which I cut/pasted).  I edited the original message.

[ctviggen]

Ah, I see.  If it's built for it, I'd do it.  So, you really don't have to do anything other than hook up cables.  The connectors on a JR are cool, although you can only use spades.  So, basically, the entire power is simply split between the two outputs (per side).  Interesting.  It has about twice the power of my amp (mine's 275w/channel into 4 ohms and yours is 500).  That's also cool that you don't have to buy another amp (which I really don't think I'll have to do, but I guess I'll find out once I get the RM40s/30s).

[ekovalsky]

Here is a response from Rick Maez, technical guru at JRDG and a very cool guy, when I asked about the stereo 302 versus the biamp 302/4.  There is not a huge cost difference between the two amps, considering the 302/4 has twice the number of ICEpower modules it is a "bargain" of sorts  

The Model 302/4 will provide better sound quality since each channel has a discreet amplifier section per output channel, whereas the M302 will mean a shared amplifier output section for the high and low connections on each channel.  The output power of the Model 302/4 is the same as the M302, though when the amp is on the test bench it performs differently than a M302.  Here's why: a Model 302 has only two channels of output, left and right.  When fed a full scale signal, the left and right channels draw so much power from the power supply that it limits them to 300 watts each before it reaches its limit and can't supply greater power.  With the M302/4, there are four channels of output, L1, L2, R1, and R2.  When fed a full scale input signal, there are twice as many output sections drawing power from the power supply, so it reaches it's limit sooner and that happens to be around 250 watts for each channel simultaneously.  Here's the catch: in your lifetime, you'll never find a piece of music or soundtrack score with all or both input channels being fed full scale at the same time and the load will never be the same on the lows and the highs at the same time.  Since each channel can "borrow" from each other if needed, there's always going to be some headroom available in the power supply and you'll actually see a real world output power of 300 watts or so in real world use.  The reserves are the same, but the demand upon those reserves is doubled with the M302/4, though you'll never test the limits of all output channels simultaneously in the real world (only us weirdos with test benches manage to do that).  The M302/4 doubles into a 4 ohms load.