Unexpected Benefit

[DougMac]

I just received my 340/170 Home Theater setup. At the same time, I ordered a Panasonic SA-XR57K receiver. I'd heard some good things about it and I was intrigued by the digital amps. I ordered it because it's been discontinued. I plan to set up sometimes in the future a small LCD in the den to augment the HT. No reason to use bulb time to watch SD TV! At worse, I could use the receiver for the den.

I didn't know when I ordered it that there's two main speaker connections, A and B. I also didn't know that the unit can be configured to bi-amp fronts! Although it doesn't say explicitly (the manual is written for the average consumer), it looks like there's some active EQ applied. They were very explicit about hooking the LF to the A amp and the HF to B, else it wouldn't sound right.

I'm not expecting miracles, but it will be nice to have a little headroom for the 340's. I'm going to try it tonight.

I do have a technical question. Am I correct in assuming the only connection between the high and low sides of the crossover are the external removable jumpers? Also, if I use two different amps in this instance to drive the high and low sides, what is the impedence presented to the amp? The Panny likes 8 ohms and won't be as happy with 4.

Doug

[Sam1000]

Although I did not bi-wire,bi-amp 340 with Panny, 340 were easier to drive with xr57. I would not be worried too much about 340 dipping to 4ohms. You can also take a look at the impedance graph for 340.

There was a nice post from Dave on bi-amping, but I can't seem to find it.

[DougMac]

There was a nice post from Dave on bi-amping, but I can't seem to find it.

This may be the post to which you refer:

http://forum.ascendacoustics.com/sho...bi-wire&page=2

I don't think I'll be doing any harm by trying it, but from reading Dave's post, I may derive no benefit and may actually degrade performance. I'm concerned about what low pass or high pass filters may be activated by the Panny. Since there's no documentation, I have no idea where they rolloff. They may have decided on a point completely wrong for the drivers, actually creating a "hole" between the two drivers. I can always leave the jumpers in place, then one at a time connect the A & B outputs. If there's active EQ in the amp, I could always do sweeps to get a ballpark on the crossover point and the nature of the slopes.

It's no biggy. I'll probably run two wires to the mains anyway, just for the additional gauge.
Doug

[davef]

I'm concerned about what low pass or high pass filters may be activated by the Panny. Since there's no documentation, I have no idea where they rolloff. They may have decided on a point completely wrong for the drivers, actually creating a "hole" between the two drivers.

Hi Doug,

When receivers (like yours) offer a bi-amp function, both amplifier outputs are identical. There are no high-pass or low-pass filters, aside from bass management filters which may or may not be implemented when bi-amping.

Hope this helps

[DougMac]

Hi Doug,

When receivers (like yours) offer a bi-amp function, both amplifier outputs are identical. There are no high-pass or low-pass filters, aside from bass management filters which may or may not be implemented when bi-amping.

Hope this helps

Thanks Dave.

I did have a chance to try it out last night and as you state, there's no filters on the output amps.

Whether it helped or not is hard to say. I think the 340s sounded better in this configuration, but it is hardly a scientific test and may be attributable to placebo effect. The extra headroom won't hurt and since it's already there, I'll wire my HT accordingly.

I did a little more listening and they keep sounding better and better! We had the sheetrock company over to give us an estimate. I haven't heard back yet. I'm interested in the numbers. Can't wait to get the project done.

Doug