Jadis JF-1 Crossover? Any experience?

Amended question list (partially hoping to bring the question back to life:

1) If I use an active pre-amp before the crossover (this or any other active crossover) and then use a power amp on the low frequency output and an integrated amp on the high-frquency output of the crossover, as long as I set the volume pot correctly (and carefully) on the integrated amp (in something resembling "virtual unity gain", is there any reason why I could not use a regular amp and an integrated amp and control system volume using the pre-crossover preamp? I only ask because I am desperate to tinker and while I cannot think of any reason why this would not work, I recognize that I am more than capable of overlooking something obvious.

2) repeat of original: does anyone have any experience using a Jadis JF-1 tubed crossover?

3) general crossover question: Putting attenuators AFTER the crossover strikes me as being a better solution than supplying a variable voltage input into the crossover. The problem is then that one is left with a number of attenuators or a very complex and expensive box to build. Is there another way around this I am not aware of?

Thanks all.

T-bone -- if I understand correctly: you have a pre, you have an active xover for yr particular speakers, and there is no passive xover doubling up in the system. You also have one integrated amp + 1 power amp. Correct?

1) You set the two amps to ~equal sensitivity using the volume pot on the integrated. Then you control system volume via the pre volume control. OR, if you have attenuation @ xover level, use that instead and play yr integrated at full or optimum level.

2)

Does the crossover internally take care of the difference in sensitivity that the speakers it was meant for

I wouldn't know. Can't Jadis advise on this? I see quite a few controls on the pic; what are these -- or, failing that, why don't you check the output @ the xover point, 1-2octaves above & below.

3) I'm a bit confused...sorry. You already have 1 volume control on the integrated to "match" (hopefully) yr two amps' sensitivity. If you're asking about a passive xover -- then the volume "control" becomes part of the xover circuit. Best to use an Lpad. Is this what you're asking??
Cheers

Hi Gregm, thanks for posting. It was your comment several months ago which pulled the idea of bi-amping the system out of the cobwebbed areas of the gray matter.

Yes to most of your assumptions... current amps are 1 pair monoblocks, 1 integrated; the speakers have external passive crossovers originally (but for the sake of the question I omitted that) but I have also recently come across an active crossover (which I have read (but cannot confirm) that Jadis made specifically for the speakers (have sent email to Jadis tonight to confirm anything and everything I can). However, the crossover is a 2-way crossover for 4-way speakers (which means that everything above 180Hz is going to have to go back through the passive crossover unfortunately).

1) That's what I thought. Thanks for confirming.

2) The Jadis active crossover has four pots (1 each for bass L/R and treble L/R) which adds to the mess of using a pre-amp before and an integrated afterwards. I had forgotten that I had my system up with pictures... oops. I was trying to ask the amp/integrated question on a generic basis and the paperwork question specific to the Jadis JF-1.

3) The question was more of a theoretical design question with regard to active crossovers. My 'concern' was whether the variability of input voltage penalizes the results of an active crossover to a degree which would favor the expense of putting attenuation after frequency filtering. It would require parallel output circuits with multiple attenuators (not cheap) but it would keep the crossover circuit gain constant and keep the overall circuit simple.

3) Penalise? Not really. Plus it's a grand pain to avoid gross energy losses and impedance disasters when using many attenuators. You have attenuation already designed into the circuits -- use those.

2 These xover pots are useful to "equalise" the sensitivity levels of yr two amps (i.e. so that they output the same power/voltage level for any given input).

You might want to set the integrated at unity as you note, and then compensate for low-level listening every now & then by upping its volume a bit...

Overall, the scheme should work very well.

Gregm, Thanks much for taking the time. I am re-arranging things this evening (oops, just turned morning) to hook everything up. Someone from Jadis overnight confirmed my understanding (JF1 built for Jadis Eurythmies w/ xover at 180Hz, 12db slope, tubes: ECC82s, pots: Alps 100kOhm linear (but they did not offer documentation, or even a date of manufacture)). I will report as I can.