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Old 01-27-2023, 09:45 PM
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miatadan miatadan is offline
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Question Question’s re: Output Taps

A few years ago when I had the MC302 power amplifier, I had the Martin Logan Spires connected to the 8 ohm taps, for whatever reason it sounded better than the 4 ohm taps but the amplifier would run for hours with the heat sinks just getting slightly warm. Do not even matter if I had it at max volume ( 300 watt peaks )

I then sold the Martin Logan’s and purchased Magnepan MG 1.7i speakers.
At first I hooked up the Magnepan’s to the 8 ohm tap , like the Martin Logan’s but after about a half hour the amplifier at just past 30 watts output, shut off and go into protection. Heat sinks would be hot enough to burn your hands. I was forced to use the 4 ohm taps and no more issues with heat sinks getting hot.
But the sound quality was not the same as when at 8 ohms. This goes back to 2016.

Later in 2018 replaced MC302 with MC312 ( part of insurance replacement due to break-in. At that time changed to Magnepan MG 0.7s as moved to apartment with smaller living room . I used the 4 ohm tap, afraid to try 8 ohm tap with past experience.

This January replaced the MC312 with MC462 power amplifier. Noticed that the 8 ohm, 4 ohm and 2 ohm taps had individual + and - post compared to 1 negative post and 3 posts + for 8, 4 and 2 ohms.

Ran the amplifier at 4 ohm taps for about a week and a half. The Magnepan’s did sound better than it did with the MC312.

Last night decided to try the 8 ohm taps again on the MC462.
This time, the heat sinks are just as cool to touch as it was on the 4 ohms tap. Does not matter how loud I am playing music. And yes it does sound better on 8 ohm taps than 4 ohm taps on the Magnepan’s.

What confuses me is why do both the Martin Logan and Magnepan’s sound better with the 8 ohm tap when the recommended impedance for both is 4 ohms.

Why does the MC462 stay cool on the 8 ohm tap with Magnepan’s but the older MC302 when go into protection + heat sinks getting super hot after half a hour?

Any scientific reason for this ?

Dan
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McIntosh MR87 tuner, McIntosh D1100 as dac & preamp , McIntosh MC462 power amp, Apple iPad Pro 11” M2 cpu for media streaming, AudioQuest Carbon USB-C to USB 2.0 interconnect , Magnepan MG 0.7 speakers , JL Audio Dominion d110 subwoofer
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Old 01-27-2023, 11:58 PM
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Masterlu Masterlu is offline
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Dan… everything you mentioned above tells me the Martin Logan, and Magnepan’s are power hungry. They like having the extra headroom that the MC462 provides. In addition the MC462 has the extra power to not only deliver it, but remain cool while doing so.

As far as the impedance taps go; manufacturer recommendations are just that. I have frequently strayed from the manuals Reco’s, and let my ears be my bible.

Glad to hear you are finally enjoying your speaker’s full potential, and not adding an additional space heater in your home.
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Last edited by Masterlu; 01-28-2023 at 12:01 AM.
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Old 01-28-2023, 03:07 PM
Charles Charles is online now
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I think it's important to understand that most solid state amps are built around an optimum "tap". I have experience with the old Krells. I had an engineer at Krell explain this to me years ago. He explained that Krells were built around a 2 ohm tap. This means that a 400 watt Krell will deliver 1600 watts at 2 ohms. Modern Mac amps have much larger power supplies and better heat sinking but it doesn't change the fact that running a low impedance speaker with a minimum impedance of say 2 ohms, will over a period of years significantly reduce the life of the amp.

For example, a Wilson Sasha DAW goes for 39K. An appropriate amp for this price speaker would be around 20K, which would be a MC 611. Or a SS amp built around a 2 ohm tap. I totally understand that many will disagree but I am a proponent of running the SS amp so that under most conditions it is under stressed operating under optimum conditions, i.e. no impedance mismatch.

However, if you 462 is always running cool, well, who can argue with that??

Best

Charles
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Charles Updated System: Wilson McIntosh Audioquest
New gear on order: MC2.1KW Anniversary power amplifier; C12000 An preamplifier; MCD12000 An SACD/CD player; AQ 1 meter Dragon balanced IC; 2 meter AQ Hurricane HC power cord; 3 meter AQ Hurricane Source power cord; unspecified 3 meter AQ digital coaxial IC and power cord for my backup MVP851 DVD player given as a surprise gift to me by my dealer
Most recent updates: Latest is the last one posted: AQ Diamond USB replaces AQ Coffee; Wilson Audio Specialties Alexx replaced by Wilson Audio Specialties XVX Chronosonic; new subwoofer crossover; new Galaxy Grey Thors Hammer; Wilson Pedestals; heating and cooling completely reworked and reinsulated resulting in a much quieter, cooler, and more efficient room (cost about 10,000.00). McIntosh MCT 500 SACD/CD transport; Wilson Audio Acoustic Diode for XVX Chronosonic; WEL Signature digital Coaxial cable for MVP 881/D1100 digital connection replacing the optical connection; New plinth for Thor subwoofer made of X material with the Wilson Acoustic Diodes; Thor is now off my floor; MC3500MKII mono block amps (2) and two custom granite slabs; Wilson ActivXO Stereo Electronic Crossover; new 75-ohm multi-directional FM antenna for tuner; total of eight additional Wilson Audio Heavy (red) pedestals placed under the MC3500MKII mono blocks; JRiver Media Center 31
Amps: McIntosh MC3500MKII mono blocks (2), McIntosh MC1.25KW’s (3). All amps set on floor on custom made granite slabs
Preamp and DAC: McIntosh D1100
Sources: McIntosh MCT500 SACD/CD Transport, MVP881 BR player, MVP851 DVD player, MR87 tuner, Marantz 510LV Laser Disc player, ASUS laptop USB (JRiver Media Center 31)
Speakers: Wilson Audio Specialties XVX Chronosonic; custom made Wilson Acoustic Diodes
Sub-woofer: Wilson Audio Specialties Thor’s Hammer (1) horizontal lie; custom plinth of X material with Wilson Acoustic Diode feet; Wilson ActivXO Stereo Electronic Crossover
Cables main system: Audioquest WEL Signature speaker cables and balanced IC (preamp to amps); WEL Signature AES/EBU balanced digital IC for CD playback; WEL Signature digital coaxial cable for MVP 881/D1100 digital connection; Audioquest Diamond optical (1) for tuner, (1) for MVP 851 DVD player, and (1) for LD player for total of (3); Audioquest Diamond USB cable; McIntosh MCT cable for SACD playback; Dragon power cords (5 HC cords and 3 source cords for total of 8); Thunder HC power cord for MR87 tuner
Cables subwoofer system: Audioquest Redwood speaker cable (1); Wolf balanced subwoofer IC from ActivXO crossover to amp; Wind balanced IC from preamp to ActivXO; Hurricane HC (2) and Dragon HC (1) power cords
Power conditioners: Audioquest Niagara 7000 (1) and Niagara 5000 (3); (4) dedicated 20-amp lines with no. 10 wire straight out of fuse box
Isolation: Wilson Pedestals for D1100; MVP881 BR player; MCT500 transport; Wilson Audio ActivXO electronic subwoofer crossover; plinth for Thor subwoofer made of X material with the Wilson Acoustic Diodes; eight Wilson Audio Heavy (red) Pedestals placed under the MC3500MKII mono blocks (four placed under the rails of each amp)
Cabinet: Double Custom Woodwork & Design (CWD) solid walnut cabinet on large casters; holds all sources and preamp; also, Niagara 7000; 11 feet minimum distance from speakers
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AC: Dedicated to this room only, an ultra-high efficiency and quiet recently installed Ruud split system 3-ton heat pump.
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