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My experience with RS-4.5s and biamping (long)

The original electronic crossover with the 4.5's sucked on the high end. Perhaps caps and newer op amps would help, when I was running mine I used the bypass switch to defeat the high crossover, and just used the crossover for the bottom end.

Since I have switched to an ashley xr-2001, and very pleased with its performance. I crossover at 300 hz, but I am running infinity beta woofers, with no passive crossover in the speakers. The ashley is 24db slopes, and for example, if you listen to just the bass, it sounds like crap with that rolloff, but that disappers when it blends in with the top of the cabinet working. the ashley is quite surprising in transparency of the mid and high frequencies sound reproduction, very nice.

tubes on the tops, ss on the bottoms....
 
phaedrus said:
Just an observation (not a disagreement), but it seems like most of the people in the Infinity forum (not just this thread) who prefer a single amp over biamping are mixing and matching their amps. I suspect part of the issue they have over biamping may arise from this.

When you have two non-identical amps, you get into issues of gain differences, different amp topologies and voicings, output impedances, etc. When using a single amp, that doesn't arise. Personally, I biamp everything, but always with amps that are either identical or higher/lower powered amps from the exact same amp family with identical designs (eg, SAE A301/A501).

Again, just an observation, but I wonder if using significantly different amps for the highs and the lows doesn't create some of the issues people experience with biamping.

David
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David, I agree with you, using different amps complicates the issue. Just for the record, though, I did try 2 identical Bryston 4B ST amps with the 4.5s. I still preferred using the Marchand crossovers to the Infinity but it was easier to get a decent blend with the Brystons.

In my room the Infinity woofers just loved to hammer the room resonances and so the steep 24 dB octave slopes helped to tame the low end. It would be easy to misadjust the crossover controls to get really lousy sound.
 
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kmanusa said:
David, I agree with you, using different amps complicates the issue. Just for the record, though, I did try 2 identical Bryston 4B ST amps with the 4.5s. I still preferred using the Marchand crossovers to the Infinity but it was easier to get a decent blend with the Brystons.
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Yeah, I don't doubt the Marchand is superior to the stock Infinity crossover. I wasn't really thinking of the Infinity vs. aftermarket crossover issue, I was more thinking about the "one big amp" vs biamping issue.

I suppose one way of dealing with it would be to vertically biamp, and eliminate the external crossover entirely.

David
 
People who bi amp with tubes on top and SS on the bottom with different brand amps dont seem to run into this phenomenum.But using SS top and bottom differently branded seems to do what Dave is talking about.Why this is,is strange.Any ideas people.
 
phaedrus said:
Yeah, I don't doubt the Marchand is superior to the stock Infinity crossover. I wasn't really thinking of the Infinity vs. aftermarket crossover issue, I was more thinking about the "one big amp" vs biamping issue.

I suppose one way of dealing with it would be to vertically biamp, and eliminate the external crossover entirely.

David
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Sorry Dave my response was kind of all over the place. I guess what I was trying to say was that using 2 identical amps worked best for me when I biamped. But even with 2 identical amps, I could not get quite the coherence that I got from the speaker driven full range with a single amp. Despite that, I ended up biamping mostly to control the level of the bass although the L-R slopes helped too.

Actually your point about vertical biamping is a good one in that I did try passive vertical biamping with the Brystons and I liked it a lot. No active crossover and a really lively, punchy sound.

Chris has a bigger and probably better suited room for the 4.5s and I hope he will be able to get even more out of them than I did. I still believe they are the best full range speaker I have owned. If I had the scratch to finish off our basement and create a dedicated media room down there, I'd have kept them and moved them down there.
 
i think the idea of them blending the best with one amp (or passive vertical biamping) makes some sense. after all, that's the shallowest slope of all the options and thus the gentlest handoffs. infinity's manual says just this, as well. if i felt a real lack of fill in that crossover region, i'd be much quicker to use an active and biamp. i will certainly be experimenting more when i get some amps back from the shop, but there is also the possibility of further tweaking the passive crossover. if you peek at the schematic, you can see that by adjusting the values of the shunt cap on the Watkinses and the HP cap on the EMIMs, one can shelve the response a bit around ~200Hz.
 
I would have to add to this by saying the performance of an amp(s) can also contribute to the sound of the speakers. I have tried 3 identical pairs of amps in both vertical and horizontal active biampflication modes. As well as single amp. Each brand sounded so much different it quickly became apparent I can in no way ever determine if I have "the best sound" possible.
 
I've ran 4.5's since brand new in 83, I've used tubes and solid state, always found horizontal biamp the best, also it work's well with the xo box, for controlling amps of different impedences, IF you want the best out of the 4.5's THEY HAVE to be EQ'D, YOU can not get a flat freq response from them, either by passive or active xo, I used 31 band eq's and sound anaylizer for yrs and eq them flat!!! . I now use a DBX Driverack and let the eq wizard do all the work for me, The payback in the quality of sound the 4.5's will produce and the imaging factor alone one of the best I've ever heard, and I heard alot, and own alot of high end as well, the 4,5's excell. The best investment you can make for your 4.5's IS EQ them FLAT!!! If you don't,,,sell them to someone that will, cause if thier not worth that simple investment, thier not worth having. You have no idea of what your missing. Sorry for the brunt, but had to get it off my chest. Al
 
Tell me a bit more about the DriveRack which model are you using?

I do not have the extra active xover I have a set of the real early models and the xover was optional ?

So I can use the one from my IIBs but I was thinking of going 3 way active for the mids and highs
and using the LC network for the watkins.

I have bought a Behringer 3 way Xover for this purpose and more than enough amps

Looking at these DriveRacks the 260 and PA2 models have a 3 way xover built in thoughts?
 
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I use the DR 260, also have the DR 482 but is a PIA to use without comp, the DR+ also is a 3way, I prefer 2 way because I can do a premature eq of speaker with it's controls and finalize with the DR, another reason I prefer 2 way is the emit's and emims are protected better against amps that emit a bit of DC. I found the passive to sound better left in loop, than a 3 way setup, a +-2db can raise real hell on music, especially if one is going up and the other is going down, once eq'd you'll never look back :) Al
 
Dr 260

InAp said:
I use the DR 260, <snip>
Al
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I have a question about the DR260: Are you running it single ended (low level) in and out? Or converting to differential into the DR then converting back to low level going to your amps?
Thanks!

Ed
 
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