"Activating" Vistas

OK, I've been itching for some time to do some improvement to my setup, namely, I wanted to beef up the power stage - Marantz NR1601 that I have is a very decent piece of equipment, however, it is not "officially" rated for 4 ohm load, let alone for Vista's electrostatic panel that goes down to 1.2 ohm @ 20k.

Anyway, long story short, I've bought a couple of ICE Power amplifiers modules, specifically, 50ASX2, a complete 2-channel class D device with onboard SMPS, so that one only needs to provide power directly from the wall socket, the line level input, connect the thing to the speakers and, optionally, to the standby control circuit.

According to the specs, a single module can drive a pair of 4 ohm speakers and provide each with 40 watts of clean power with less than 0.05% THD in full audio range 20-20k. Moreover, in the bridged mode the module can easily drive one 4 ohm load as well (100 watts < 0.09% THD), which, btw, implies that a single channel can also drive a 2 ohm load.

Now, I have a choice to turn my Vistas into 2-way complete active speakers. Or, instead, I could bridge the 2 channels on both modules so that the resulting 100 watt bridged amplifiers will drive the woofers.

I‘ve already played with the modules and they work beautifully – I have not done any measurements yet, but they sound just fine.

Now, my problem is that ideally I would like to mount them inside the speaker base; however, I am pretty sure if I do it I will void the warranty. Also, I have no idea of the internal layout of the base and whether there actually is enough room to place the amplifier module and provide enough air circulation according to the manufacturer’s thermal design guidelines. The modules don’t have heatsinks and use free air for the cooling.

So, for the time being I am going to mount the modules in external vented enclosures – still looking for suitable ones.

Any suggestions are welcome.

I would not mount amplifier modules in speaker enclosures unless they were specifically designed for that.

For external, vented enclosures, check this site:
http://www.hammondmfg.com/

I agree with Bernard never put any amp in a speaker,
even in a miniscule way it reduces the volume of the cabinet.
If you dont mind me saying you could use much more than 40 watts.

Tengizk said:

Now, I have a choice to turn my Vistas into 2-way complete active speakers. Or, instead, I could bridge the 2 channels on both modules so that the resulting 100 watt bridged amplifiers will {also} drive the woofers.

Click to expand...

I don't know the Vistas at all, but just going by general power requirements of MLs, I would go with the bridging option. As Beek says, you could use more than 40 watts.

You could always start with that, and when funds permit, buy two more modules and "activate" the Vistas. How much do the modules sell for ?

Also have to consider in the bridge mode can the amps handle the load

If you can go balanced why not use a y adaptor and put 2 amps behind the Vistas using short speaker cables & horizontal passive bi-amp.

Gentlemen, thanks for the replies.

Yes, I could go higher than the extra 40 watts per transducer (which is 80 watts per speaker), although it's already plenty loud for my not very large room. Anyway, the best option for higher power module would be ICE Power 250ASX2 (or older model with no onboard SMPS - 250A). But the trouble is that the ICE Power modules are not normally sold in retail. Yes, you can occasionally get them from eBay, etc. but currently this particular model is nowhere to find. The older 1000 watt module (1000ASP - the one used in Jeff Rowland, Wyred4Sound) is now available, however, according to the manufacturer's specs it does not really like low impedance loads @ high frequencies. So, I am not sure if they would be any better when used with ESL compared to less powerful ASX2 line.

Regarding mounting the modules inside the base – I certainly understand the argument that you don’t want to interfere with the driver-cabinet interaction reducing the volume, but since the modules are tiny compared to the cabinet, I am not sure it would be a big problem. As is said before, voiding the warranty is – so this is out of question. At least until the 5 year period is over.

Regarding adding two more modules and bridging them into four 100 watt amplifiers – unfortunately, the bridged module is only good for driving the woofer, but for the panel it’s not as suitable as it has twice the output impedance compared to single ended option @ high frequencies. Now, I cannot claim that it would result in audible difference at normal listening volumes, but I at least want to be sure that I use them in the best possible way in terms of transparency and neutrality.

Thanks. Again, suggestion and advice are very welcome.

i am using the BelCanto M-300's dont know
if thwy are stock modules rhey are doing pretty good so far full range.
Good Luck

I don't know either what they use in BelCanto, but B&O's IcePower line actually covers wide range of applications. And there are some killer module combinations for active multi-way speakers.

Below are a couple of pictures of IcePower 50ASX2 used as a two-way speaker amplifier for Vista. Surprisingly, the hardest part was to learn how to crimp the JST terminals for the board connectors as I am an old school guy and am more used to soldering irons rather than crimping tools. The rest was really piece of cake. I will probably do some experimenting on the weekend and also take some electrical measurements.

My worry, though, is that finding the right enclosure would be a problem – the right sized, vented and good looking box – I am probably out of luck.

I have the same prob when I DIY stuff it looks awful.
Then after you look around the good cases are pricey (they see us coming) then you still gotta drill & stuff.
I also have D unit with a linear supply 525 into 4 that I like (but it needs work) Will start that when I get back home.
I am thinking of putting the BC on the Vista bottoms & a a/b that can swing 2 ohms on the top that has level controls.
But gotta get off my lazy ass.....