McIntosh amps a good match for Acoustat electrostatic speakers?

[nathanso]

I've been driving my newly acquired Acoustat 2+2 speakers with my McIntosh MC7300 amplifier off the 2-ohm taps and they sound quite good. But with the speakers I also acquired an Acoustat TNT-200 amplifier that is supposed to be the ne plus ultra amp for driving Acoustat speakers.

I've been advised by an Acoustat expert that the c.1983 TNT-200 should be refurbished before it will sound up to spec and that's about a $400 job.

My question is, does anyone have experience driving Acoustat speakers from a McIntosh amp, particularly an Autoformer-equipped Mac? Is this supposed to be a good match or am I giving up better sound by not using the TNT-200?

 

[howiebrou]

Forget the speakers! Look at the view! :jawdrop:

 

[Victor]

The local stereo shop has some used Acoustat speakers and they sounded great on MC501's. I would think the MC7300 would also be a great match.

It would be fun to fix up the Acoustat amp for a comparison but if I were you here is what I would do. Sell the Acoustat amp and take that money and the money you saved from not fixing the amp and get some good room treatments. At the local stereo shop we listened to the Acoustat speakers in 2 rooms and I liked them better in the more dampened room.

Victor

 

[Number 9]

I remember listening to a pair of 2 + 2s at a dealer long-ago. Very impressive sounding ESLs.

IIRC correctly, they "loved" power and had a wicked impedance.

Sounds like a job for the MC501 or 1201s to wrastle them into submission. The autoformers I think, will make a big difference.

 

[bear-hifi]

Sorry! i have to ask... where is that view coming from???

 

[nathanso]

View from our front door in lovely Briones, CA, a rural area about 15mi NE of Oakland. I've wanted to do sound treatments in this room for a while but with an 18ft cathedral ceiling it's not a trivial undertaking, and the windows cannot be covered without making a serious trade-off.

 

[Victor]

I would recomend ASC tube traps. For room treatments they look good and they can be easily moved for tuning your room. They are expensive though. I would start with 4 traps, 2 behind the speakers and 2 on the side walls.

Victor

 

[ron-c]

Mc amps will work well with these speakers. The MC7200 was designed to drive these also.

Thanks,
Ron-C

 

[skippy_ps]

Beautiful room and beautiful view.

Murray

 

[nathanso]

Just an update on this topic after some testing with the as-yet unrefurbished Acoustat TNT-200. The TNT-200 beats the MC7300 hands down in my system. Bottom end is noticeably more solid, but the most obvious difference is one of greatly enhanced detail. The twin subwoofers I was running are all but unnecessary with the TNT-200. I guess Jim Strickland really knew what he was doing!

 

[Victor]

One more win for synergy, I'm glad you are enjoying your system.

Now get your TNT-200 refurbished and it should get even better.

Victor

 

[JChrisA]

What tap would be the best sound? The 4 ohm tap might have better bass
Electrostats have high impedance in the bass and low impedance
in the treble. I used a Threshold amp S200 on the spectra 22 with great results.

 

[ron-c]

I would suggest the 4 ohm tap on the 7300.

Thanks,
Ron-C

 

[basite]

no idea what would be the best, but that's a georgeous system and a georgeous view :thmbsp:

Keep them spinning,
Bert.

 

[PHC1]

That view IS something else. :thmbsp:

 

[SilverTpt999]

Acoustat 2+2 specs

I would suggest the 4 ohm tap on the 7300.

I realize this is a thread resurrection but there isn't enough info out there on these stats... and I just acquired my own pair of used 2+2's, so I thought I'd share some of the research I've done over the past few days so others can benefit.

According to the manual I have, specs for the Acoustat 2+2 list it as a 4 ohm nominal load - so that tap on the amp should be fine. My Harman/Kardon PA2400 (rated 170W/ch into 4 ohms) is barely warm driving them at solid listening levels. The McIntosh should have no problems on the 4 ohm tap.

Other rated specs:
Freq response: 28 -20 000 Hz (+/- 2 dB)
SPL: 115 dB at 20' in a 16' x 24' room (Program material peaks)
Minimum power requirement: 50 W (many sources say this is pretty lean for the 2+2s and recommend closer to at 100 W minimum but the manual does claim 50)
Nominal Impedance: 4 Ohm
Power Consumption: 5 Watts (for the high voltage interfaces, hence: Electrostatic. Doesn't say whether it is 5W per speaker or total, but it doesn't really matter with this low of a draw.)
Control: High Frequency Balance (above 10 kHz, this was removed from the external box with the Medallion revision -C interfaces)

So the manual I have is for the -A or -B revision of the interfaces, not the -C, but the specs should not change (performance is another matter). Note that the Medallion modified older versions OR the later -C interfaces do still have a treble adjustment but it is a custom-made resistor with a slider, internal to the box, rather than a potentiometer accessible from the exterior.


To add another amp that seems to have good synergy with these aging but still excellent stats, the Harman Kardon PA2400 has more than enough brute force to drive them well with excellent finesse. Its predecessors in the Citation line should perform similarly, but I don't have any on hand to compare.

Acoustat also recommended leaving the interfaces plugged in at all times, which seemed unusual enough to warrant mentioning. Apparently they perform best when they've been plugged in for a decent period. Definitely put a surge protector between them and the wall, though. It doesn't have to be audiophile grade as the bias voltage circuit is completely separate and distinct from the signal path through the interface - I have the schematic to prove it.

If anybody would like a copy of these manuals, PM me.

 

[nathanso]

Hi Silver,

Congrats on finding your 2+2s, I think you'll be very pleased with them. If you haven't replaced the three electrolytics in the input circuit yet I would recommend doing so. I replaced mine with North Creek Zens (now out of production) and the result was an obviously smoother and more extended top end. I needed to reduce my HF Balance pot from max to 1/2 scale after the cap job.

I just read through this old thread and thought I'd post an epilogue: I did end up refurbishing (and heavily modding) my TNT-200, and it sounded glorious, but I ended up selling it so I could run balanced interconnects. I went to a Hafler 9505 but sold that too after hearing a PS Audio HCA-2, which should do it for me for a while. This nondescript class D amp is, imho, a perfect match for the 2+2s. It's a major bargain, too, at today's used prices ($600-700).