Magnepans and Amplifier Current

[restorer-john]

I frequently get asked about Maggies and have to explain the points @CDMC has made about them. There appears to be a mythology that has grown up around them in the audiophile community that they require welding type amps. Not the case.

Consider Maggies have been around a long time. People in 1970s would buy large receivers, with high continuous 8 ohm ratings to run their maggies. Trouble was, a lot of 1970s high powered receivers had very aggressive current limiting for 3/4 ohm loads. Current limiting that was quite audible.

Then along came high current amplifiers in early 1980s and maggies were happy. I think the "you need an arc-welder" it is a hangover from those days.

 

[BDWoody]

I would say, that for an amplifier that claims to double going from 8 to 4 ohms, the specification for the 8 ohm output is underrated.

I have an amp that is rated 250/350 into 8/4 ohms.

Had they specified it as 175/350 instead, it would seem to "double".

Isn't the Krell KAV 250a 250/500 into 8/4?

You mentioned you had one of those, but of course you likely have others.

Always been curious about that amp, and how it would compare to a modern amp with similar specs.

 

[restorer-john]

Always been curious about that amp, and how it would compare to a modern amp with similar specs.

Bigger, heavier, better made and almost indestructible. Even being one of the babies in the Krell range, they are end-game amps.

 

[BDWoody]

Bigger, heavier, better made and almost indestructible. Even being one of the babies in the Krell range, they are end-game amps.

I have the 3 channel version of that amp, and the overused audiophile descriptor 'effortless' comes to mind. It just happily and quietly does it's job.

I haven't had the need, but it can also be bridged to 1000wpc. They can be bought for @$1k these days. Not sure what I'd have to spend to match that in a new amp, but glad I don't have to.

Edit:. Bet they used decent Caps...
(Too soon?)

 

[restorer-john]

They can be bought for @$1k these days.

An absolute bargain and hard to comprehend anyone would give them away for that.

 

[RayDunzl]

Isn't the Krell KAV 250a 250/500 into 8/4?

Yes.

Always been curious about that amp, and how it would compare to a modern amp with similar specs.

Compare it to another traditional Class A/B it probably does pretty well. I haven't measured it.

 

[CDMC]

Isn't the Krell KAV 250a 250/500 into 8/4?

You mentioned you had one of those, but of course you likely have others.

Always been curious about that amp, and how it would compare to a modern amp with similar specs.

Like amps rated to double its power from 8 to 4 ohms, they have purposely underrated the 8 ohms to achieve that number. it is really 300/500:

https://www.soundandvision.com/content/krell-industries-kav-250a-and-kav-250a3-page-2

Still a wonderful amp and absolutely worth owning.

 

[BDWoody]

Like amps rated to double its power from 8 to 4 ohms, they have purposely underrated the 8 ohms to achieve that number. it is really 300/500:

https://www.soundandvision.com/content/krell-industries-kav-250a-and-kav-250a3-page-2

Still a wonderful amp and absolutely worth owning.

Not bad, considering it is one of their lower tier offerings. Not much fancy about it other than the performance. Course, it was @$4k, so not exactly cheap, but it doesn't look like they scrimped on what mattered.
As a bonus, it looks like the value of mine has actually gone up a little in the handful of years I've owned it.
I think it's still an amazing value compared to what I see out there, if I wanted equivalent performance out of something new.

 

[Wes]

if you think Magneplanar is stuck in a time-warp then you are likely attracted to bright shiny objects with no worth vis a vis SQ

they audition every new change to a speaker at least twice with 2 different setups incl. different amps

they then rate each changed speaker as to a small increment in SQ (i designation) or a larger improvement (.x is iterated)

 

[DonH56]

I'm looking to get some Magnepan 1.7i. From what I've read, they are low sensitivity, like my KEF LS50 speaker. But they also apparently like high current to be at their best.

I'm looking at getting Purify ET400a-based monoblocks. They are rated at about 425W into 4 Ohms and current is like 25A. These are supposed to be like the successor to the Hypex units. Now I know I'm on ASR and these amps should all sound the same, but for those who believe in audible differences I've heard that the Purifi is supposed to be even better sounding with improved soundstage and clarity.

The other option is Hypex NC1200-based monoblocks. They are rated at about 700W into 4 Ohms and current is like 40A.

Given the above, which is likely to get the best out of the Magnepan 1.7i speakers?

Thanks!

IMO: Either will be more than enough to turn the 1.7i's into slag and ruin your hearing forever. I cannot imagine using the NC1200, however, that just seems like extreme overkill. The Purify should be more than enough.

OTOH, I'd love to know exactly how much power these panels can take without hitting physical constraints and actual damage. I did some pulse testng once upon a time but have no memory of how much power the panels at that time (MG-I, MG-II, MG-III, Tympani-something) would take. And I was afraid to repeat the tests as I could not afford to buy them all.

I remember when I more than doubled the power from my receiver by picking up an amplifier for my first set of Maggies. It did make a difference that seemed significant to me at the time and I happily used that amplifier for many years. Noise and distortion was a little lower (measured) as well. Yup, going from the old 15 or 20 W/ch stereo to a gigantic ARC 75 W/ch amp was a Big Deal.

 

[CDMC]

if you think Magneplanar is stuck in a time-warp then you are likely attracted to bright shiny objects with no worth vis a vis SQ

they audition every new change to a speaker at least twice with 2 different setups incl. different amps

they then rate each changed speaker as to a small increment in SQ (i designation) or a larger improvement (.x is iterated)

And this has what to do with the comments that their website is at least 15 years out of date? Magnepan does move at a glacial pace. How many years has it been since they demoed the prototypes with smaller panels and dipole woofers. How many decades since they have made any substantial improvements to their designs? Their technology is mature, so I wouldn’t expect them to make any radical changes, but given their slow and necessary move to direct sales, I would expect them to update their website with accurate information and keep it reasonably current.

 

[CDMC]

IMO: Either will be more than enough to turn the 1.7i's into slag and ruin your hearing forever. I cannot imagine using the NC1200, however, that just seems like extreme overkill. The Purify should be more than enough.

OTOH, I'd love to know exactly how much power these panels can take without hitting physical constraints and actual damage. I did some pulse testng once upon a time but have no memory of how much power the panels at that time (MG-I, MG-II, MG-III, Tympani-something) would take. And I was afraid to repeat the tests a I could not afford to buy them all.

I remember when I more than doubled the power from my receiver by picking up an amplifier for my first set of Maggies. It did make a difference that seemed significant to me at the time and I happily used that amplifier for many years. Noise and distortion was a little lower (measured) as well. Yup, going from the old 15 or 20 W/ch stereo to a gigantic ARC 75 W/ch amp was a Big Deal.

The QR Maggies are almost impossible to blow or damage with too much power. By their design the voice coil is spread over a large area and doesn't get hot and doesn't have close contact to magnets. What happens is they stop getting louder and if pushed hard enough with bass, the bass panel will slap back against magnets making a horrible noise. I can't tell you the number of times Wives 1.0 and 2.0 blew the tweeter fuses in the QR panels by overdriving with no ill effects. The true ribbons used in the 3, 20, and 30 series are a different story and can be damaged, but are generally well protected if the owner leaves the stock fuses intact and doesn't oversize them.

 

[DonH56]

The QR Maggies are almost impossible to blow or damage with too much power. By their design the voice coil is spread over a large area and doesn't get hot and doesn't have close contact to magnets. What happens is they stop getting louder and if pushed hard enough with bass, the bass panel will slap back against magnets making a horrible noise. I can't tell you the number of times Wives 1.0 and 2.0 blew the tweeter fuses in the QR panels by overdriving with no ill effects. The true ribbons used in the 3, 20, and 30 series are a different story and can be damaged, but are generally well protected if the owner leaves the stock fuses intact and doesn't oversize them.

Well, I used to repair them, back before the "QR" days, and saw plenty of wires burned in two due to excessive power (usually by audiophiles who jumpered the fuses to "improve" the sound). Damaged panels from overdriving their physical limits I saw much less often but now and then would see slits where the membrane was damaged. Whatever.

 

[Wes]

And this has what to do with the comments that their website is at least 15 years out of date? Magnepan does move at a glacial pace. How many years has it been since they demoed the prototypes with smaller panels and dipole woofers. How many decades since they have made any substantial improvements to their designs? Their technology is mature, so I wouldn’t expect them to make any radical changes, but given their slow and necessary move to direct sales, I would expect them to update their website with accurate information and keep it reasonably current.

1. please point out the inaccurate info

2. same for out of date info

Note - I did not ask for things you merely dislike

 

[MRC01]

... OTOH, I'd love to know exactly how much power these panels can take without hitting physical constraints and actual damage. ...

I power my 3.6/R with an Adcom 5800, which can deliver 400 wpc continuous into 4 ohms (both channels driven). The amp has small LEDs that light up when it is nearing its power limits (1% total distortion). In the 20+ years I've owned this combo, I've tested max SPL a couple of times. A full spectrum signal that just barely lights up those LEDs (occasional flickering) measures 105 dB SPL at the listener position, and that is the point where the speaker panels just begin to rattle against the stops (maximum panel displacement) if the signal has significant low frequency content. I've never blown a fuse or damaged the speakers, so this appears to be their limit.

 

[Shazb0t]

if you think Magneplanar is stuck in a time-warp then you are likely attracted to bright shiny objects with no worth vis a vis SQ

they audition every new change to a speaker at least twice with 2 different setups incl. different amps

they then rate each changed speaker as to a small increment in SQ (i designation) or a larger improvement (.x is iterated)

None of this changes the fact that their website is reminiscent of someone's early attempts to use GeoCities. The only thing you've clarified is that you will respond in defense to any perceived slight at Magnepan. They test with 2 different amps guys!

1. please point out the inaccurate info

2. same for out of date info

Note - I did not ask for things you merely dislike

Just like the last time you called this guy out for not helping the OP despite the obvious difference in quality between your posts. He already directly quoted the website with dubious claims that at best look dated..

They insinuate that the "new" technology of Class D is possibly just not a good match for Magnepans. Some high end (expensive) models though, they may be good..

A "balanced" approach to creating a system with regards to cable expenses. I'm interested in your defense of that.

What exactly is a "musical" subwoofer? Subwoofers that can move a lot of air are sloppy and become tiresome during extended listening? Uh oh, well I guess that explains why Magnepans generally don't have any deep bass output!

 

[restorer-john]

None of this changes the fact that their website is reminiscent of someone's early attempts to use GeoCities.

I have no problems with their website. It works perfectly fine on my 33.6K modem, Windows95 and my 640x480 monitor, especially since my recent upgrade to a 486DX2-66 and 8MB of RAM!

 

[DonH56]

I have no problems with their website. It works perfectly fine on my 33.6K modem, Windows95 and my 640x480 monitor, especially since my recent upgrade to a 486DX2-66 and 8MB of RAM!

I'm pretty sure I have an old v.92, 56k, modem I can send to you... Since you're upgrading and all.

 

[ethanhallbeyer]

I have no problems with their website. It works perfectly fine on my 33.6K modem, Windows95 and my 640x480 monitor, especially since my recent upgrade to a 486DX2-66 and 8MB of RAM!

i am partial to the magnepan BBS running on Wildcat!

 

[BDWoody]

I have no problems with their website. It works perfectly fine on my 33.6K modem, Windows95 and my 640x480 monitor, especially since my recent upgrade to a 486DX2-66 and 8MB of RAM!

You could always tell who had the fast computers in college based on the speed of the solitaire animation. I was always glad I upgraded to the 40 MB Hard drive. All that extra storage was so handy.