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Integrated for bi-amping with AtmaSphere MA1s

My speakers (Ascendo ZF3s) have separate terminales for each driver.  I am currently using Atmasphere MA1s for the mids and tweets, and using a Pass X1 and Aleph3 for the woofers.  I'm also using a set of old Entec LF20 subwoofers crossed over with a Behringer Ultracurve pro for the really low frequencies.  I would like to replace the X1 and Aleph3 with a more powerful integrated, and am not sure what to use.  I've been away from this hobby for a number of years, but my first instinct when I think low frequencies is Krell.  The S300i looks intriguing, but I've read that it comes from a dark time in Krell's history, and may not be terribly reliable, and not up to the stnadards of low-frequency reproduction Krell is known for. 
Is this a good choice?  What else should I consider?
honest1
georgehifi's avatar
georgehifi
10,312 posts
 
honest1

The MA1’s OTL’s would be fast, so you need an amp to blend well with that, and yet have strong bass control, and yet with a good lower mid sound. I don’t think the 30w of the Aleph is the way to go.

If you want an integrated that can have speed good bass control and have good lower mids, Yes the Krell S300i would do, also a Gryphon Diablo 120 would be nice, or even a Pass Labs Int-60.

Cheers George
onhwy61's avatar
onhwy61
5,231 posts
 
I've never heard an Ascendo loudspeaker, so I'm just speculating based upon what I've read.  Isn't one of their major design goals a coherence of presentation.  Wouldn't all these different amps, crossovers and subwoofers negatively effect the design goal?  Why not just run it with the MA-1, or if you want to max out, multiple sets of MA-1s.
glennewdick's avatar
glennewdick
1,690 posts
 
why not use the Atma-shere MA-1 for the whole thing? in my experience the OTL’s do bass very well probably the best I’ve heard from tubes and much clearer then many SS amps out there. you could get another one for synergy if bi-amping is a must. 5ohm load could be an issue if it dips any lower. 

will say will all those tubes and class A amps I bet your room is toasty
blisshifi's avatar
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blisshifi
1,192 posts
 
Using the MA-1 for the whole thing will likely not give enough bass output as the speakers have a nominal impedance of 5 ohm. One way to make it work well is to get a set of Paul Speltz’s (anticables) Autoformers ans only hook them up to the bass terminals.


While I found that using autoformers on the full frequency spectrum on my previous 4 ohm speakers (Legacy Focus SE) narrowed the soundstage, decay, and air, I tried using the Autoformers just before the speaker cable one for the woofer section and voila - bass was full, tight, and realistic, while the mids and treble were powered directly by the MA-1 with no Autoformers. I highly suggest this route, and if you don’t have Autoformers to try out, they’re not anywhere as pricey as buying a new amp.
georgehifi's avatar
georgehifi
10,312 posts
 
@honest1



Review from 6 Moons on the Ascendo ZF3s :
"Finally in my opinion these speakers require really powerful amps to drive. It’s not obvious when you check their technical specifications as both sensitivity and impedance seem reasonable but my time with them proved otherwise."


This is the most likely reason to get a good bass mid/bass amp like I mentioned in my 1st post.
Spec’d at 5ohm "nominal" (the ZF3’s could be even lower in spots especially in the bass) and no mention of what degree of -phase angle there is, which could exacerbate any low impedance problems even further.

Cheers George
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