Bi-Amping Divas

[Waybackin67]

Greetings! I am newly registered and this is my first posting.

I am new to high end audio and decided to jump right into the deep end about a year ago after retiring and finally not having to move around the globe every 2 years. Anyway, the initial system that I built with some incredible assistance from my local Apogee-owning Yodas is outlined below. I originally purchased a used pair of Audio Research 610T amps which I had upgraded to take KT120 tubes. No news to the Apogee-experienced, but at over 700wpc of tube power I still couldn't really JAM. So I bi-amped, purchasing a Krell KSA-300S and a custom Marchand Active Crossover. This has allowed me to experience some phenomenal listening. The one downside that continues to nag at me is that while the 610Ts now have ample headroom when cranking it up, the Krell's bias meter gets pegged out...and worse, it has on a few occasions thrown its circuit breaker due to excessive heat. Fans help, but it's not my ideal long-term solution. It is clear that I need more solid-state headroom on the bottom end. I am currently considering purchasing a slightly used set of Classe CA-M600 mono-blocks. Does anyone have any experience with these in a similar bi-amping system? Other SS amp recommendations for the bottom end? Appreciate any and all thoughtful comments. Many thanks.

[Zardoz]

Hello and welcome to the world of Apogees.

As a long time Apogee owner (Caliper, Duetta, and now Diva) and a fan of Krell amps with them, I would suggest a Krell FPB 600 for the bottom. If you like the sound of the Krells but just need more head room and power, then one of these will do the job. The FPB series sound tons better than the S series and the 600 would give you all the power you need. Another option would be to get some mono Krells (450Cx, 650Cx, or 750Cx) for the bottom. Then you would really be cooking. I've driven my Apogges with Krell KMA100 (Caliper), then KSA250 (Caliper,Duetta), then FPB300 (Duetta), then FPB600 (Duetta,Diva), and finally a pair of Krell 750Cx mono's (Diva). The 750 can't be beat, but I got great sound with all of them.

Good listening,
Z

[thekong]

Hi Waybackin67, welcome to the forum!

How big is your room? I am surprised that you are having problem even bi-amping with ARC610T and Krell 300S! Do you listen very loud?

I used a pair of Sonic Frontiers Power 3 (bass) and Power 2 (mid/high) to active bi-amping my Fullrange in a 15’ X 33” X 13’ room with very satisfactory result. The same was true with 2 pairs of CJ Premier 8s.

Being said that, I am going to move into a 18’ X 28’ 6” X 10’ 10” room, and will initially bi-amping the Fullrange with 2 Pass Labs X350.5. I plan to add another pair of Pass X600.5 later for triamping.

IMHO, the Apogee is very revealing and you may have coherence problem using different amps for the bass and mid/high. I would suggest sticking with the same brand and series of amps, just pick the bigger models for the bass.

Good luck in your serach!

[Waybackin67]

Thank you for the thoughtful replies.

thekong - I don't always listen loud, but the mood does strike me often enough that I am concerned over the limitations of the KSA-300S in the long term. My listening room (multifunctional man cave really) is in an outbuilding with its own dedicated HVAC system so the heat put off my all of my amps is easily compensated for by the AC. From my listening vantage point, the room is 20' Wide x 15'6" Deep x 10' 5" High. That Pass set up sounds great - I heard some of them at Axpona in April; but I think that is too divergent a path for me now.

Zardoz - A local Audiophile is constructing (and taking a long time to do it!) a bi-amp set up with his newly acquired Full Range, ARC 610Ts, and a newly acquired pair of Krell 750Cx monos. He's older and more patient (and been doing this for about 50 years!). I probably need to wait to hear his set up before I jump headlong (again) into something else. Still, I can't see how I wouldn't be happy with the higher end Krells that you suggest. I would prefer to wait to find a great pair of Krell 750Cx monos as this seems likely to be the "final answer." I have dedicated circuits for my amps using 30amp wire and 20amp breakers. I have read that the 750 models performed better when 220. Any comment on that?

[Zardoz]

Hey Wayback,
I have heard that too about running on 220. I haven't tried it yet. My room is about the same size as yours, but I have the Divas firing down the long dimension and my ceiling is only 8' 2". There is acoustical treatment in the room, ASC tube traps and foam diffusors/absorbers.
My 750's are on dedicated lines(each one) with 30 amp wire and a 30 amp circuit breaker for each. I don't ever expect to have to replace them.
Best,
Z

[Waybackin67]

Z - Sounds like you have it sewn up electrically speaking. I have been looking for some room treatments over the last 6 months. I searched at Axpona but didn't really see anything. I need to do some additional online research. Music Direct has some options too. Unfortunately, my room doesn't lend itself to aiming the Divas down the longer portion of my room due to cabinets. If you experiment with the 220 and experience significant differences, I'd love to hear about it. While I can't find 750's on the market at the moment, I know that it's the final solution.

Thanks again for chiming in.

[EldRick]

Consider Tube Traps: http://www.tubetrap.com/