Good point.
2105 or 2505?
- Thread starter theprofessor
- Start date
Good point.
nj pheonix
Lunatic Member
FWIW
The polished SS age better
The polished SS age better
Agreed. However, I do have an original MC240, and the chassis is flawless, it depends on environment and care. Most amplifiers from the era however were stored away by Grandpa decades ago, sometimes in a humid basement or a garage and look like my pitted MC75s' chassis, which I am now burdened with replacing. New Stainless-Steel chassis will likely outlast civilization (although stainless-steel still needs to be pickled to prevent surface corrosion).
twiiii
Lunatic Member
I really liked the 2125 and the 2155, but thought the 2155 just seemed to be easier to listen to and was more faithful sound reproducer. Not by a whole lot, but there was a difference. 7150 was a real step up if driving speakers with extreme variations in impedance requiring more current. I used the 2150 and 2120 to drive Multiple Altec HF drivers and never damaged an Altec diaphragm because the the amps had power guard. Drivers rated at 40 watts could handle over 70 watts when the crossover frequency was raised to 700 HZ while bi amping. Two drivers on single horn would be fed the 140 watts output of a 2120 all day with out worries. But a 2150 was strong enough to drive two of the 100 watt out door drivers and three of the indoor drivers putting out close to 200 watts. The larger 2200 2250 and 2500 were great for driving the woofers and sub woofers. I preferred the 7300 to drive stacked arrays of Altec and or JBL super tweeters from 7,000 HZ up. Emilar drivers loved Mac amps too. Pairs of Split professional Klipsch La Scala got along great with the 2120 and 2150, too Combine 4 of them with two MWM-s as subs and you had a superb small disco system using 2200's or 2150's as the sub amplifier. The 2250 was just to much. We used Altec woofers in the MWM boxes because the lead wires for the Eminence woofers would frazzle after about 4 nights of 6 hour dance music. Power Guard didn't help here.
So remember with or with out power guard always be mindful of how hard you are pushing the system.
So remember with or with out power guard always be mindful of how hard you are pushing the system.
perryinva
IS it vintage????
170w/ch rms was not typical at all for a 2105. They’re good, but not that good. More like 130-140. I have a set of A25s as well, & a 2105 is way more than they can handle, but good synergy. Heck, even the 1900 is more than plenty, and it’s half. At that power range, speakers efficiency is everything.
onemug
Super Member
Agree. When I bought my 2105 'brand new', the dealer tested it at 150 wpc. Their tech told me that's what was expected and that's what it put out when I took it to DOB's clinics for the next 16 yrs. My later 2505 tested at 73 wpc at those clinics... and those numbers were 'from 20hz to 20k'. Many amp brands would test at more wattage in their midband but lose it at the extremes.
nj pheonix
Lunatic Member
Never tested myself. I thought I heard Terry Dewick or C_dk mention that #.
Realistically it doesn't matter.
Realistically it doesn't matter.
perryinva
IS it vintage????
Exactly, double the power to get a 3dB increase rule of thumb, right? So an extra 20-30watts makes little difference at 110. However, that “extra” power is just a safety margin for clipping avoidance headroom, and allows the amp to run cooler in its normal operating range.
I have wondered if the newer amps have that same generous over design.
I have wondered if the newer amps have that same generous over design.
nj pheonix
Lunatic Member
Generally mac is conservative in their ratings.
I can't say for sure but again if they are capable of 25-50% over Ratings, it makes little difference. I think few of us need the extra ( note I didn't say none) will be missing anything at rated power.
I can't say for sure but again if they are capable of 25-50% over Ratings, it makes little difference. I think few of us need the extra ( note I didn't say none) will be missing anything at rated power.
We switched from the MC240 to the MC7300 on Altec Nineteens last night, ... no difference in dynamics running 30mW peaks on the meters.
I feel like in a well-designed amp, no such thing as too much power. However in the example above where “”extra” power ... allows the amp to run cooler in its normal operating range.”, not always true.
A Class A amp will typically run much warmer at 30% of rated output than near its limits (assuming constant power, which music rarely is). Sometimes you can just hit that warm-running point, which by the way all McIntosh amps are designed to dissipate safely so a moot point.
When I run my older McIntosh gear as background music / all day, I usually worry about the aging of two things: Tubes in tube amplifiers, light-bulbs (and their heat on plastic components) in older SS amps. The electronics are fine.
I feel like in a well-designed amp, no such thing as too much power. However in the example above where “”extra” power ... allows the amp to run cooler in its normal operating range.”, not always true.
A Class A amp will typically run much warmer at 30% of rated output than near its limits (assuming constant power, which music rarely is). Sometimes you can just hit that warm-running point, which by the way all McIntosh amps are designed to dissipate safely so a moot point.
When I run my older McIntosh gear as background music / all day, I usually worry about the aging of two things: Tubes in tube amplifiers, light-bulbs (and their heat on plastic components) in older SS amps. The electronics are fine.
McIntosh had always touted a written "Performance Guarantee" whereby the customer would receive a full refund if a unit was unable (or could not be made) to meet published spec. I suspect McIntosh had intentionally underrated its products to ensure that such a circumstance could never occur - and probably never did.
Throughout a number of independent evaluations over the years, reviewers often noted that the unit in question could be rated for x% higher than published spec while still meeting FTC regulations for advertised power ratings.
Throughout a number of independent evaluations over the years, reviewers often noted that the unit in question could be rated for x% higher than published spec while still meeting FTC regulations for advertised power ratings.
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damacman
Resident Psycho
caddy, I bet being a McIntosh dealer back then was like shooting fish in a barrel ...
Probably so- at least until the early '70s. I think things got a bit dicey for a while toward the end of that decade.
damacman
Resident Psycho
Many up and comers targeted the McIntosh dealer network ... that's a fact.
nooboy
Active Member
I was a bit surprised when I saw that a c28+2105 would get the a25s to a loud, full, but not at all unhandled sound at around 12 ish for both. Have been experimenting with 2 and 9, respectively, and it's quite interesting, more aerated and precise. Using the C28 phono stage. Man, there are so many variables with this set up.
Bill S
Thread Killer
The MC2505 is a very musical amp. Some suggest it was the most tube-like sounding SS amp Mac made. Mine is in a 20x25 room with 12' ceilings open to the rest of the 1st floor. With Polk LS50s as mains it plays as loud as I can listen to it with gain up to 80% and Mac pre volume at 12:00. With a Velodyne servo sub it pounds and never gets more than warm. I love the sound and have no desire to look further at this point. Tested at 72 wpc. You could double the power and gain 3db but its not needed.
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nooboy
Active Member
Self-correcting after a few weeks, for posterity: yeah, no, 3/4 to full open on the 2105, about 10:35 to 11:15 on the 28 is the sweetest range. To my ears and gear.