I am ordering a pair of KEF iQ90 3-ways to use as my FL/FR speakers and I want to bi-amplify them using solid state amps for the low end and a nice Class A amp for the high-frequency Uni-Q driver.

Here's the "plan" with questions for the great members of this forum:
a 100-150W solid state stereo amp for the low-frequency drivers on the 90s (looking at used naim, B&K (ST-140 monoblocks or a reference 125.2), used Bryston and a serious look at the NAD Masters M3);
then a [100>___W] stereo amp for the 6.5" Uni-Qs (possibly a class A design - suggestions? should I stick to solid state ABs for now to see if that sounds great before spending the extra $?);
finally, I'm going to pick up an active crossover to add to the signal path before these amps. Should I be looking at Rane or Behringer or are there "high-end"/DIY offerings to strongly consider?

Any amplifier suggestions?


Does anyone have any suggestions as to where I should cross the iQ90s (250Hz or 2.5Khz?) to start? Do I need to get this information directly from KEF or do I just need to experiment? According to KEF's product specs, they are crossed at 180Hz and 2.5Khz - 180 seems too low to me but 2.5Khz makes sense as I only want to push the Uni-Q driver with a low watt, class-a amp for smoother highs.
What measuring equipment should I pick up to successfully, actively, bi-amplify my KEF speakers? I.e. setting crossover frequencies, correct phase, etc...
Should I just hire someone from one of the many highly-regarded shops in NYC to dial them in for me? I.e. is this too difficult a job for a novice?
If I called KEF's support line, would they be very helpful with the nitty gritty details?

I'm thinking about a tube amp like the McIntosh MC250 for the high-frequencies. Would this be a wise choice?

Using different amps can cause level matching problems that can't be overcome. Do both amps have the exact same level sensitivity over their entire gain settings? Not likely. I would only use matching amps to be sure the levels matched at all volume levels.

Using different amps can cause level matching problems that can't be overcome. Do both amps have the exact same level sensitivity over their entire gain settings? Not likely. I would only use matching amps to be sure the levels matched at all volume levels.

If the solid state or hybrid tube amp has L/R gain controls, can't you "dial-in" the set-up?

Example:
Using a Cary 308 (http://www.audioreview.com/cat/amplification/amplifiers/cary-audio-design/cad-308sa/PRD_322063_1583crx.aspx) with a NAD 2700 (http://www.audiogon.com/cgi-bin/cls.pl?ampstran&1247198543&/NAD-2700-THX-excellent-conditi)

Where can I go to research these types of set-ups? I'm having a hard time finding a resource that "brings everything together."

Your speakers are not that expensive so why are you wasting $$$ on more amps and crossovers? Amps do not improve sound, better speakers (designs/crossovers), room treatments improve sound.

Keep in mind the Speaker $$/electronic $$$ ratio should be about 4:1 when considering higher end designs so if you truely want a better sound and you want to spend $$$$, upgrade your speakers.

If you are going the DIY/active crossover route, DCX 2496 is the bargain $$$ choice ($300), DBX driverack ($500) is higher up and then BSS omnidrives are high end studio quality choices ( bss omnidrive fds-388 ($1K+))

But I wouldnt actively crossover your speakers period. if you want to go this route check out DIY and you can have drivers many times better then those Kef drivers for less $$$.

btw, I have an active 3-way system!

Your speakers are not that expensive so why are you wasting $$$ on more amps and crossovers? Amps do not improve sound, better speakers (designs/crossovers), room treatments improve sound.

Keep in mind the Speaker $$/electronic $$$ ratio should be about 4:1 when considering higher end designs so if you truely want a better sound and you want to spend $$$$, upgrade your speakers.

If you are going the DIY/active crossover route, DCX 2496 is the bargain $$$ choice ($300), DBX driverack ($500) is higher up and then BSS omnidrives are high end studio quality choices ( bss omnidrive fds-388 ($1K+))

But I wouldnt actively crossover your speakers period. if you want to go this route check out DIY and you can have drivers many times better then those Kef drivers for less $$$.

btw, I have an active 3-way system!

That is certainly great advice and I appreciate it. However, I'm on a "non-conforming" upgrade path because of my love for other hobbies so these plans are more "here and now" than dropping $3k+ on a pair of speakers.

I like the point-source/co-axial Uni-Q drivers a lot. I purchased the iQ30s+iQ60c and an Emotiva XPA-3 after listening to dozens of different speakers to make sure before I jumped in head first with KEF. I crave their high-end detail, spot-on bottom end and off-axis attributes. My apartment is 18x9 and I'm trying to "cover" the 18' side so it's challenging to keep listeners near the sweet spot. These iQ30s treat everyone in front of them to clear highs and beat up everyone in front of them with tight, quick bass. When you're off-axis (i.e. walking around the place), the sound stays very clear and motivates you to return to the listening area. I also like that KEF provides a realistic amount of bass because I experience a lot of live music (and high-end "club" systems reproducing recordings) and it's always tighter/faster/"more low-key" than most speakers these days present. I've never had a bass drum rattle my spine, pleasantly at least, but I have had my chest near the monitors and felt the entire ensemble of low/mid frequencies punching my ribs and culling out smiles :).

I have had more people tap their toes or girls get up and dance at my place with my iQ30s opened up than my friend who just got Paradigm Studio v60s and a B&K reference 200.2. I'm not going to lie, his set-up sounds *much* better (much much much) to the critical listener but the low end can be "oppressively" fine... ...if that makes sense. I want to say that his set-up glues you to your listening position with a *very* wide soundstage that makes you feel as if you're a part of "what's going on" and if you move, you're going to blow it (or worse, insult the band ;)).

I'm going to buy the XQ , KEF Reference series or other high-end "co-axial" speaker in another year or so but I want to "milk" these iQs for what they're worth before I upgrade. I can afford the high-end electronics that people are offing at bargain prices these days but I can't afford even a pair of KEF 201/2s :rolleyes:. I might approach 2:3, amp:speaker spend which I'm comfortable with for the time being (~$800 for the high-freq amp and ~$300 for something from the '90s that can grab a hold of the bottom end).

I come from the headphone world where I have $1,300 worth of Headroom ultra preamp and amp (not to mention the $200+ sound card in my PC and other, more expensive sources) motivating my $400 (at the time, now around $300) Beyerdynamic DT-880s so I can appreciate the experience to be had by high quality signals/amplification. Now that I'm in the "big leagues" (haha, riiiight ;)), I want to continue to use my philosophy which has paid off big in the past.

If the solid state or hybrid tube amp has L/R gain controls, can't you "dial-in" the set-up? ...

No because if you match the amps gain at 65dB and then rase the volume to 90dB one amp may reach this point before the other since their gain signatures will be different.

Your speakers are not that expensive so why are you wasting $$$ on more amps and crossovers? Amps do not improve sound, better speakers (designs/crossovers), room treatments improve sound.

Keep in mind the Speaker $$/electronic $$$ ratio should be about 4:1 when considering higher end designs so if you truely want a better sound and you want to spend $$$$, upgrade your speakers....
Agreed 100% why are you spending such sums for amps on these speakers? Keep the amps you have and by better speakers and your sound quality will improve substantially. Bi-amping will provide subtle improvements at best. I'm about 6:1 on speakers.

William:

Thanks, that's very important information for me. How are people running unmatched amps in bi/tri-amplified set-ups? Are they constantly "tweaking" to get the best sound from each source/recording at different output levels?

I don't want to have to tinker around when I have company over because that's not very smooth.

Penn:

Thanks again for your input, I just noticed that you've taken to helping, helpless me again :D

Used Hafler's. DH220's on bottom and mids, 160 on top is what I grabbed off e-bay. Cost effective. I used a Behringer cheap crossover to start with, and found it good enough I never built an "esoteric" one so I grabbed a DCX to play with.
Mixing amps is no big deal if you pay attention to phase. My B&K 140 is 180 out from my Haflers. Just swap leads. Rotel, Parasound, B&K,NAD are all excellent, but the name brings a higher price. Leave the tubes alone for now as that puts you into a totally different price/maintenance range. It is easy to say Cary, Mac, Jolita when you are not the one paying for it!

I agree with Penn, you would be far better off to start with better speakers. How about DIY? Seas, Zaph, AE, or a few others. Solid proven designs.

I don't think bi-amping would put the life in the Kef mids. I have a pair of Q1's in my office. I was thinking about playing with them, but will just make new ones. It is a shame, they do a lot of things right.

Used Hafler's. DH220's on bottom and mids, 160 on top is what I grabbed off e-bay. Cost effective. I used a Behringer cheap crossover to start with, and found it good enough I never built an "esoteric" one so I grabbed a DCX to play with.
Mixing amps is no big deal if you pay attention to phase. My B&K 140 is 180 out from my Haflers. Just swap leads. Rotel, Parasound, B&K,NAD are all excellent, but the name brings a higher price. Leave the tubes alone for now as that puts you into a totally different price/maintenance range. It is easy to say Cary, Mac, Jolita when you are not the one paying for it!

I agree with Penn, you would be far better off to start with better speakers. How about DIY? Seas, Zaph, AE, or a few others. Solid proven designs.

I don't think bi-amping would put the life in the Kef mids. I have a pair of Q1's in my office. I was thinking about playing with them, but will just make new ones. It is a shame, they do a lot of things right.

Great advice, thanks.

Yeah, the whole tube thing is shaping up to be a dead end for me. There's a lot of "I feel" going on in that privileged circle and I don't have the time or money to experiment with $2k+ equipment. The only option there for me might be one of the Cary hybrid amps like the aforementioned 308SA.

I'm trying to pick-up a Bryston 3B ST locally for <$900 with more than 5 years on the warranty... I haven't heard the Brystons (I bet I have at a club but wouldn't have known) so I'm going by other individual's experience but I have heard that they are bulletproof (20-year warranty, I like companies that will offer that) and can "grip and rip" any low-frequency driver out there. On the other hand, I've heard that the Brystons can be too accurate for some speaker's high-end reproduction. If I find this to be true, what could I do to pair a more laid-back amp with the Bryston for the high end? Am I just going to bring myself perpetual pain?

P.S. Everyone agrees with Penn. Should I just agree with Penn? :p

Perhaps one of your could throw some of your expertise at this question: http://www.avsforum.com/avs-vb/showthread.php?t=1146343

I just picked up a Bag End Infrasub-12 about 30minutes ago :D

Bryston's are very good. When I last listened to new amps, I bought the B&K as it was 1/3 the cost and I could not hear the difference. They are built like tanks and will last forever. That is the true meaning of "pro". Being bi-polar vs MOSFET, they are respected as having solid "balls".
Basically, if you can hear a difference in amps, at least one of them is doing something very wrong. I lined up all the ones I could afford that sounded the same and bought the cheapest.
There is no such thing as too accurate. Anything that is not exactly as put in is distortion. As an example, Cary's are sweet. Too sweet actually; that would be the even order distortion tubes produce. Some use this as a mask for poor recordings or worse, poor speakers. A matter of taste. If I could afford a set of Cary triodes for when I was in the mood, sure, but 99.9% of the time, I want my system to be accurate.

BTW, Penn and I don't always agree, but he is usually reasonable. A lot of other posters are as well. Of course, a few are surely lunatics, but that is what makes this so much fun. It's a hobby, so when someone gets too serious, LOL!

Bryston's are very good. When I last listened to new amps, I bought the B&K as it was 1/3 the cost and I could not hear the difference. They are built like tanks and will last forever. That is the true meaning of "pro". Being bi-polar vs MOSFET, they are respected as having solid "balls".
Basically, if you can hear a difference in amps, at least one of them is doing something very wrong. I lined up all the ones I could afford that sounded the same and bought the cheapest.
There is no such thing as too accurate. Anything that is not exactly as put in is distortion. As an example, Cary's are sweet. Too sweet actually; that would be the even order distortion tubes produce. Some use this as a mask for poor recordings or worse, poor speakers. A matter of taste. If I could afford a set of Cary triodes for when I was in the mood, sure, but 99.9% of the time, I want my system to be accurate.

BTW, Penn and I don't always agree, but he is usually reasonable. A lot of other posters are as well. Of course, a few are surely lunatics, but that is what makes this so much fun. It's a hobby, so when someone gets too serious, LOL!

Thanks! I hope I can get this Bryston for a reasonable price. If not, my good friend as a B&K Reference 200.2 that I can try out to see if it's as good with the KEFs as it is with his Paradigm Studio 60s... Powerful is definitely the adjective to describe the B&K so I would probably expect the same from the Bryston based on what I've read.

No because if you match the amps gain at 65dB and then rase the volume to 90dB one amp may reach this point before the other since their gain signatures will be different.

I disagree.

Afaik, once the levels are matched, they stay matched unless the limits of one is reached before the other.

[SIZE="4"]finally, I'm going to pick up an active crossover to add to the signal path before these amps. Should I be looking at Rane or Behringer or are there "high-end"/DIY offerings to strongly consider?




Why?

IMO, stacking crossovers generally only serves to screw up all the hard work KEF put into designing the ones in the speaker.

Why?

IMO, stacking crossovers generally only serves to screw up all the hard work KEF put into designing the ones in the speaker.

I believe that active bi-amplifying requires a crossover before the high and low frequency amplifiers. When wired, they do defeat some of the crossover work in the speakers but one should be able to achieve the same results externally.

I believe that active bi-amplifying requires a crossover before the high and low frequency amplifiers. When wired, they do defeat some of the crossover work in the speakers but one should be able to achieve the same results externally.

Yes, it does. But, usually that means removing the internal crossover not connecting an external one on top of it.

Also, it's possible there are features built into the speaker's passive crossover that cannot be duplicated by off the shelf external units.

Yes, it does. But, usually that means removing the internal crossover not connecting an external one on top of it.

Also, it's possible there are features built into the speaker's passive crossover that cannot be duplicated by off the shelf external units.

I assume that the internal crossover for the Uni-Q assembly is preserved when using the speaker's bi-wiring posts with the bridges removed.

That is certainly great advice and I appreciate it. However, I'm on a "non-conforming" upgrade path because of my love for other hobbies so these plans are more "here and now" than dropping $3k+ on a pair of speakers.


Im cool with that :D

But there are lots of better ways to explore alternatives in this hobby. We can only suggest them, its still your money and 100% your choice to have fun with it! I have waste more $$$ then you could image just because wanted something, not because it was right ;)

I assume that the internal crossover for the Uni-Q assembly is preserved when using the speaker's bi-wiring posts with the bridges removed.


Yes, I'm sure it does. That's my point; or at least one of them, anyway.

Yes, I'm sure it does. That's my point; or at least one of them, anyway.

I'm close to getting this Bryston 3B ST. I'll hook that up and I'm sure that I'll be happy for the next month or two ;)

Sounds about right.

Nice amp, nice speakers, leave it be. Good plan.