2. amps-preamps
  3. 1227530459

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

Showing 8 responses by rtn1

rtn1 OP
535 posts
 
Zdravo, here's an update: I've got the Karan Acoustics M 1200 monoblocks. More info to come...

For now:
1) Dual monoblock design with balanced circuit and power.
2) Over 2kw into 4 ohms.
3) First 75% of power is class A.
4) Each weighs 167 lbs.
5) Stays on 24/7 - at idle, consumes a few hundred watts and measures 91.8 F at the heat sinks.

Hvala for all the recommendations and help.
Rob
rtn1 OP
535 posts
 
I think this is a good discussion. The Karan slides the bias to achieve class A, but is touted to be unique in the way this is accomplished. I am not an engineer, so I cannot speak to whether this makes sense. Milan Karan designed the amplifier to use balanced power (+60, -60), and has designed a circuit to send a signal to increase the bias prior to the main signal. Thus, the claim is that the bias is increased fully and proportionally to the main signal before the main signal passes through. So maybe the argument is how effectively the bias can be increased ahead of time.

Is there anyway to measure class A power other than the continuous power it draws from the wall?

Of course, all this is beside the point when considering what the amplifier actually sounds like. 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.

Does any of this make sense?
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.
rtn1 OP
535 posts
 
My system has been posted. Thanks again for everyone's help.

Rob
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?"
rtn1 OP
535 posts
 
Clavil,

I'd like to experience the Hovland Stratos and DCS Scarlatti with the Isis. I'd imagine it would be quite special and a different flavor than what I have. If you perceived some excessive slowness, then I wonder whether there is a room or speaker set-up issue at play.
rtn1 OP
535 posts
 
The Isis do benefit from good power, and lots of it. While amps like Soulution, Vitus, Dartzeel, FM Acoustic may have their merits, I think 100-200 watts is too little. I would look for something with a lot of class A, at least 300 watts into 4 ohms. Amp matching with the Isis is so crucial. Nothing else will come together until you get that part correct. The overall efficiency does not belie how much power it takes to get those woofers moving like they should.
rtn1 OP
535 posts
 
Cpcorreia,

I agree it is a risk and it may be worth it, so perhaps you just have to try. However, I would be prepared to forgo the Soulution and try at least 1-2 other amps for direct comparison.

As I said, I've spoken to a number of Isis users who have moved-on because I believe they did not strike that synergy with equipment or room. What the Isis really do well is to convey the weight, scale, and perspective of large pieces, but it requires power. If you can play a large orchestral or choral piece, close your eyes, and have a fairly accurate representation of the orchestra and the hall, you are done. If you are not getting that, then the speakers are not doing what they can do.

Paradoxically, I found that Pass to sound more effortless and majestic than the Karan's. I attribute this to the pure class A power among other things. The Karan's put out over 2kW into 4 ohms, so they are a real force for power. There are not many amps on the market which require two power cords per chassis. I still remember ordering new fuses for those amps, and someone from the store called me to make sure I ordered the right ones because they were rated for an incredible amount of current.

If you must keep the Soulution and have no flexibility with the amp, I might recommend you look at other speakers. If you've decided on the speakers, can be flexible, and willing to experiment, you can be rewarded.
More to discover