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Best Solid State for Avalon Isis

I would appreciate informed comments regarding best solid-state synergy with Avalon Isis. I’m looking for an amp that will maintain absolute control of deep bass, while maintaining a rich and dynamic mid-range, and clarity without sacrificing musicality. It should be transparent, and allow a vast and layered soundstage to appear. Although the Isis appear relatively efficient (90db at 4ohm), the paired 13” woofers are going to need an amp with muscle.

Source is a Wadia 9 series. It runs direct. It does not need a pre-amp.

I listen to big, loud, congested orchestral music (ie. Mahler, Bruckner, Wagner). I like to hear all the detail, including the musician's technique and subtle alterations in tempo. Orchestral sections need to have mass. I want to feel the bass at low in addition to high volumes.

My room is 20 x 30 ft, and has plaster walls/ceiling with wood floors and padded area rugs. Tubes are not an option. Because of the room and source, I am not looking for an amp that is artificially fast or tipped toward the higher frequencies.

A company which is solvent, established, reliable, and with good customer support is important, with preference for an American manufacturer. I plan on trying to home demo some of these, but need advice on where to concentrate and expend my efforts.

These are some I'm considering, and additional suggestions are welcome:
Pass Labs XA200.5
Boulder 1050 Monoblocks
Halcro DM78
Spectral DMA 360
Edge NL Sig One
Hovland Stratos

Thank you,
Rob
rtn1
bombaywalla's avatar
bombaywalla
1,957 posts
 
Rtn1,
Is there anyway to measure class A power other than the continuous power it draws from the wall?
you could get hold of a 10W resistor & put banana connectors or spades on its terminals. Then connect it to your amp's speaker binding posts. Feed a low amplitude signal into the amp, measure the output signal & note the power consumed from the wall. Increase the amplitude of the input signal. The output amplitude should also increase. Does the power consumed from the wall increase? if yes, the amp must be sliding its bias. Increase the input amplitude & see if the power consumed from the wall increases each time.
If the power does not increase, then the amp must be biased in fixed class-A mode (wherein it should be dissipating ~4X the power w.r.t. its output power).

However, I do believe that in general an amplifier should sound better in class A than in class AB, with all other things held constant.
It is generally believed that a class-A amp does not have x-over distortion hence its sonics must be better than a class-AB amp. This is just 1 aspect.
yes, if 2 amps are practically identical in amplifier circuit topology, power supply, components used then perhaps yes.
In the real world you could have a marginal class-A design that is out-done by a much better implemented class-AB design.
rtn1 OP
535 posts
 
Here is a clue regarding how much power is pulled from the wall. The Karan 1200 has a true dual monoblock design (4 power cords total, 4 on/off switches) with 4 fuses total. I ordered 4 replacement HiFi fuses, and here is the response I got:

______________________________________
"Would you please give me a call in regards to your order for 4 of the HiFi tuning 16Amp Slow Blow fuses. When I placed the order for this item with the importer, he asked me to confirm the amperage and size of the fuses on this order. Large 16A fuses are a pretty uncommon value, since that value implies that each fuse would be protecting a device that could pull almost 2,000 Watts from the wall and you’ve ordered 4 of them.

Because of this, the fuses are not in stock here in the US and would have to be special ordered from Germany. Before we do this, we need to confirm that 16A is in fact the value you require.

So, could you please confirm that you actually need 16A fuses and to eliminate confusion, what device you plan to install these fuses in?"
flg2001's avatar
flg2001
543 posts
 
I have had several Avalon speakers (but not the Isis in particular) - The best sound came out from a Gryphon Anthileon followed bt a Rowland 8.

Hope ths helps you out.
glai's avatar
glai
442 posts
 
I used to own the diamonds and tried many amps. As far as solid state goes, I strongly prefer the Boulder 1060 over the rowland 312. Switch mode power amps and ceramic drivers are not a good match ( too dry),. The best sound was from the Luxman pure class A amps. I would think Gryphon would be good too. I also tried pass x.5 and pretty good too. No exp with Karan. Tubes also good but another story all together.
rtn1 OP
535 posts
 
Thanks to all for the advice.

I settled on the Karans based upon several people who have actually heard them with the Isis. Roy Gregory from HiFi+ used Karans for his Isis review, and I thought that review was very accurate. I find most reviews to be quite vague in lathering-on the praise, but this one was consistent with my own listening. Roy also has separate reviews of the Karan 1200 and 650s.

For tube amps, I think the choices are basically CAT, BAT, and VTL.

For other SS amps, I think the choices include Boulder 2000 series, Ayre, and Spectral. Gryphon may be good, but no one heard this combination. I think the key with solid state is to have something that is powerful, and with a full mid-range.
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