Amp for 4 Ohm Speakers

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A

ashergill

Enthusiast
Hello everyone,

I am in the process of acquiring a pair of Vienna Acoustics Concert Grand speakers, with the following specs:

Three-way, floorstanding, reflex-loaded dynamic loudspeaker. Drive-units: 1.1" silk-dome tweeter, 6" X3P-cone midrange driver, three 7" XXP-ribbed, XPP-polymer–cone woofers. Frequency range: 28Hz–22kHz, limits not specified. Sensitivity: 91dB/W/m. Impedance: 4 ohms average.

This will be for a 2.0 setup for now (and probably a 2.1 in a few months), strictly for music. I don't listen to music at high volumes, but definitely have varied interest (including some classic rock, alternative, postrock/instrumental, some classical, a little jazz, and a lot of old Indian music which tends to have poor recording features, but nothing I can do about that.)

The room is 17 x 21 with 10" ceiling; it opens up into another roughly 18 x 20 x 10 area. The receiver I am most interested in is Marantz SR7005(as a pre/pro of course), as I would like to be able to stream from my PC/iTunes, and play via internet radio. I will be adding a TT as well, likely a Music Hall 5.1 (or 7.1 if I can find a good used one.)

So, the big question: any recommendations for a good 2 channel amp (around $1000) that will drive the VAs at 4 ohm without any difficulty? The ones I have short-listed (new and used) based on my research are:
ATI AT1802 or 2002
Rotel RB1572
Emotiva XPA-2

I've also come across a few Bryston and McIntosh on Audiogon, which I understand to be outstanding amps but these tend to be really old (still worth it??) Any firsthand experience regarding the specific models will be appreciated. Would also love to hear from anyone who has the VA concert grand speakers, and what they're being driven with.

Thanks for taking the time to read. I am new to higher-end gear, to feel free to enlighten me about nuances along with your recommendations :)

AJ
 
BoredSysAdmin

BoredSysAdmin

Audioholic Slumlord
Of new units I'd choose Emotiva XPA-2.
Nothing wrong to search audiogon for good old amp, Probably one of the first on my list to look for would be Quad amps..

p.s: So you are investing large amount of money to listed music streamed from internet? :eek:
 
AcuDefTechGuy

AcuDefTechGuy

Audioholic Jedi
I can vouch for the ATI amps. They are always conservatively rated. The AT2002 is also truly fully balanced from I/O. It also has a no-fuse circuit, so you don't have to worry about replacing any fuses. I had amps in the past that I had to replace the fuses on.

I've bought 3 ATI amps from Classic Audio Parts on Audiogon since they are authorized ATI dealers (I've called ATI and confirmed). So you get the full 7 yrs warranty. They even gave me a free trigger cable with each amp.:D
Apparently Classic Audio Parts also sells Theta amps since ATI is the parent company of Theta Digital.

ATI also makes some amps for Mark Levinson, Lexicon, JBL, Earthquake Sound, and Outlaw Audio, among 1/2 dozen companies.:D
 
A

ashergill

Enthusiast
Thanks for the reply guys. I'll give the Quads some thought as well. I've been doing way more research into amps than I thought I would. There just seems to be so much to know about them, and I am finding it quite interesting. More than anything else, the McIntosh have me intrigued. (As this is essentially my first serious music setup, I won't go overboard and am looking forward to a long, but slow and deliberate upgrade path.) In particular, the MC2300 and MC2105 look very appealing, and it appears that the latter are fairly easy to find in good condition on eBay or Audiogon or some used-McIntosh internet shops with good reviews.

Would something like the MC2105 be a good investment, even though it would be 20 or more years old, and no warranty? It appears from the specs that they should be able to power 4 ohm speakers like the ones I'm acquiring. What I'm wondering is whether, like old cars, these are more suitable for people who can tinker with them a bit and change out old parts/cables etc., something I'm not keen to do. Thoughts?

BoredSysAdmin said:
p.s: So you are investing large amount of money to listed music streamed from internet? :eek:
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Not quite. I'm not buying this stuff to listen to streamed music, but would also like to be able to stream. Primary listening will, of course, be with my CDs and records. If the streamed stuff sounds horrible, I imagine I won't do it very long. If it sounds good, then it sounds good ;)
 
A

ashergill

Enthusiast
GranteedEV said:
Are you any good with a soldering iron?

Because a pair of Hypex UCD700 module amps will be beyond sweet :D

Efficiency is sky-high, so you won't need ridiculous amounts of heatsinking.

:D
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Never soldered a thing in my life! I would probably make a big mess of it :)

As of now, I'm leaning toward either a new ATI or perhaps a vintage McIntosh. Having a tough time making up my mind. By the way, does 105W (looking at MC2105) at 4 ohm through a McIntosh sound enough to drive those 4 ohm VA speakers, or am I setting myself up for disappointment? I keep reading that extra power is a good thing, but extra power in the form of a McIntosh would be out of the question at this time. Part of me says to just get the ATI with more power than the McIntosh, but I can't get over the look of the Mc.

Thanks!

AJ
 
P

PENG

Audioholic Slumlord
ashergill said:
Never soldered a thing in my life! I would probably make a big mess of it :)

As of now, I'm leaning toward either a new ATI or perhaps a vintage McIntosh. Having a tough time making up my mind. By the way, does 105W (looking at MC2105) at 4 ohm through a McIntosh sound enough to drive those 4 ohm VA speakers, or am I setting myself up for disappointment? I keep reading that extra power is a good thing, but extra power in the form of a McIntosh would be out of the question at this time. Part of me says to just get the ATI with more power than the McIntosh, but I can't get over the look of the Mc.

Thanks!

AJ
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Yes it looks good but whether it gives you enough power would depend on the speakers sensitivity, your listening habit and environment. The MC2105 should deliver what the specs say and more but its performance curves indicate rapid rise in distortion once the 105W is exceeded but still below 0.5% THD, IMD etc. at double that output during peaks.
 
Swerd

Swerd

Audioholic Warlord
Are your speakers the VA Beethoven Concert Grands, as in this Stereophile review?

The reviewer noted that these speakers were less sensitive, 87 dB, than the manfacturer claims at 91 dB. Be aware of that.

The best way to estimate how difficult speakers are to drive is to look at the speaker's impedance vs. frequency curve, the solid black curve in figure 1 of the review.



The manufacturer claims 4 ohms impedance overall, but around 100 Hz, the impedance drops well below 4, to under 3 ohms. The reviewer says, "this will stress tube amplifiers, given how much musical energy can be present at that frequency". I think that is a gentle way of saying, these speakers need plenty of power. Also be aware that the amplifier used by the reviewer is a brute, 1000 wpc at 8 ohms, 1800 wpc at 4 ohms, and stable below 4 ohms.

I'm not saying you need an amp like the reviewer had, but perhaps the MacIntosh you mentioned might not be enough for these speakers. If I had that choice, I'd go with one of those ATI amps.
 
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A

ashergill

Enthusiast
Swerd said:
Are your speakers the VA Beethoven Concert Grands?


The reviewer noted that these speakers were less sensitive, 87 dB, than the manfacturer claims at 91 dB. Be aware of that.

The best way to estimate how difficult speakers are to drive is to look at the speaker's impedance vs. frequency curve, the solid black curve in figure 1 of the review.

The manufacturer claims 4 ohms impedance overall, but around 100 Hz, the impedance drops well below 4, to under 3 ohms. The reviewer says, "this will stress tube amplifiers, given how much musical energy can be present at that frequency". I think that is a gentle way of saying, these speakers need plenty of power. Also be aware that the amplifier used by the reviewer is a brute, 1000 wpc at 8 ohms, 1800 wpc at 4 ohms, and stable below 4 ohms.

I'm not saying you need an amp like the reviewer had, but perhaps the MacIntosh you mentioned might not be enough for these speakers. If I had that choice, I'd go with one of those ATI amps.
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Yes, they are the concert grands. And, I did read that article a while ago, but must admit that - being new to this stuff - I didn't quite know how to interpret the numbers/graph. Your post is very helpful. I think that I'll go with ATI or something like it with plenty of wattage, and wait for a higher-powered McIntosh (MC2500 perhaps) to come along at the right price somewhere....

Thank you all for chiming in! :)
 
AcuDefTechGuy

AcuDefTechGuy

Audioholic Jedi
I don't understand how come the McIntosh amp is 105 watts into 16 ohms, 105 watts into 8 ohms, and 105 watts into 4 ohms???:confused:

Shouldn't the power output increase when you go from 16 ohms to 8 ohms, and from 8 ohms to 4 ohms???:confused:

Anyway, 105 watts/4 ohms is 105 watts/4 ohms, which is not very impressive regardless of brand name IMO.
 
Z

zumbo

Audioholic Spartan
AcuDefTechGuy said:
I don't understand how come the McIntosh amp is 105 watts into 16 ohms, 105 watts into 8 ohms, and 105 watts into 4 ohms???:confused:

Shouldn't the power output increase when you go from 16 ohms to 8 ohms, and from 8 ohms to 4 ohms???:confused:

Anyway, 105 watts/4 ohms is 105 watts/4 ohms, which is not very impressive regardless of brand name IMO.
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McIntosh amps have different locations for the + to connect depending on the ohm load. It's a rail voltage reduction. Linear Power used the same type system in car audio. They had taps inside the amp that could be switched.

Their saying is you get the power you pay for, no matter the load.

Us LP guys knew to leave the amps on the 4ohm taps to get the double power for a 2ohm load.
 
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P

PENG

Audioholic Slumlord
AcuDefTechGuy said:
I don't understand how come the McIntosh amp is 105 watts into 16 ohms, 105 watts into 8 ohms, and 105 watts into 4 ohms???:confused:

Shouldn't the power output increase when you go from 16 ohms to 8 ohms, and from 8 ohms to 4 ohms???:confused:

Anyway, 105 watts/4 ohms is 105 watts/4 ohms, which is not very impressive regardless of brand name IMO.
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They use a output transformer so the output voltage can vary to match the load impedance.

http://www.berners.ch/McIntosh/Downloads/MC2105_own.pdf

They call it "autoformer". I am quite sure they are actually autotransformers in proper electrical engineering terms.
 
P

PENG

Audioholic Slumlord
zumbo said:
McIntosh amps have different locations for the + to connect depending on the ohm load. It's a rail voltage reduction. Linear Power used the same type system in car audio. They had taps inside the amp that could be switched.

Their saying is you get the power you pay for, no matter the load.

Us LP guys knew to leave the amps on the 4ohm taps to get the double power for a 2ohm load.
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I didn't know you beat me to it.:D
 
Z

zumbo

Audioholic Spartan
TLS Guy said:
Yes, and I think it a lousy system.
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Actually, it's not. Depending on the difficulty of the load the speaker presents, you have the ability to connect the speaker to whatever posts you choose. It's your option, and a very cool option to have.;)

Just like the Linear Power 4ohm/2ohm internal taps, the McIntosh amps are more than capable of allowing a low ohm load connection to the 8ohm posts.
 
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AcuDefTechGuy

AcuDefTechGuy

Audioholic Jedi
Yeah.....but....it's.....still.....105.....watts.

Isn't that kind of.....hmmm.... girly?:D

Now that Denon POA 6600 amp is manly with 250 watts into 8 ohms and 450 watts into 4 ohms.
 
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