Do any of you remember the Hafler JF2000 (aka Rockford Fosgate RF2000)? This was another amp that could double down. Julian Hirsch with Stereo Review at that time had a similar testing experience where the amp ran out of input power trying to achieve 1KW+ output power into a 1ohm load.
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Magnepans and Amplifier Current
- Thread starter ethanhallbeyer
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MRC01
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You mean it tripped the circuit breaker for the power outlet it was plugged into? Typically that would mean it drew > 20 amps at 115 VAC.
I can't find the archived Stereo Review article online anymore so not sure where it ran out of power. I also remember it blowing fuses when pushed into low impedance loads too. Both Rockford Fosgate (purchased Hafler) and Soundstream, mainly car audio companies took an adventure into home audio in the late 1980's and early 1990's. The home amps they made at that time were very impressive with a ton of reserve power.
MRC01
Major Contributor
It's not unusual for powerful amps. My Adcom 5800 used to trip the breaker occasionally when being turned on (sudden rush of current due to big power supply caps). I checked the panel and it was only a 15 amp breaker so I moved it to a 20 amp circuit. It can draw max 1800 VA at full power.
Found it, review starts on page 50. I was a little off on it doubling though, apparently RF underrated the amp at 200W per channel so it looked like it would double and then some with that rating. I owned one of these many years ago and even with the specs it has, the amp was built incredibly well. I've never seen a 1KW toroidal transformer in a home amplifier, but this one had that, as well as two huge 40,000uF PS filter capacitors. If I recall, it also used sixteen 20A MOSFET transistors per channel in the final output stage. John France at Hafler apparently co-designed this amp with Jim Fosgate. To me, it is kinda of a neat piece of amplifier history. https://worldradiohistory.com/Archi...iFI-Stereo/80s/HiFi-Stereo-Review-1989-06.pdf
By the way, hello everyone and glad to be a new member of ASR. The thread has been an especially good read for me. I previously owned a pair of MMG's, MG12's and MG1.6's. Used a Sunfire 2-channel amp on those for a few years and then got out of the whole high power thing. The MMG's were the only pair of Maggie's I've heard bottom out with the Sunfire. The MG12's and MG16's seemed like they could just keep on taking more power if it were available.
I used to look at the glow on the Sunfire's lamp to determine if it were under a heavy load. I used that amp to power 3 pairs of Bose 901's in parallel at an outdoor party once and watched it brown out many times (We did this with the Rockford Fosgate too and it bottomed-out some of the 901's 4" drivers). That almost never happened with the Maggie's so I think they do present a fairly benign load to an amplifier that can deliver at 4 ohms.
I used to look at the glow on the Sunfire's lamp to determine if it were under a heavy load. I used that amp to power 3 pairs of Bose 901's in parallel at an outdoor party once and watched it brown out many times (We did this with the Rockford Fosgate too and it bottomed-out some of the 901's 4" drivers). That almost never happened with the Maggie's so I think they do present a fairly benign load to an amplifier that can deliver at 4 ohms.
MarkS
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Wow, this is a great site for us old-timers!
Welcome Aboard gatesgt.
MRC01
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What a blast from the past! The ad for Polk 10B speakers on page 4 brought back some great memories; I used to own a pair.
Has anyone had any success using Hypex UCD based modules with Magnepan MC1's? Probably an odd-ball combination, but I'd like to buy a set of MC1's to use with my Audio Control Rialto 600 zone amplifier. I have a decent subwoofer to supply the low end and the Rialto can be setup to filter off some of the low frequencies from the MC1's with a switch in the back.
MarkS
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Me too! You can find Julian Hirsch's review of them in the January 1980 issue.
The Polks were my first "audiophile" speaker. I bought them at "The Audible Difference" in Palo Alto, which was an incredibly cool establishment.
I drive a set of ML electrostatic speakers with a Hypex nc502mp amp and it has been cool running and so far no observed issues or problems. Not apples to apples but close. Supposed to be good down 2ohms IIRC.
That’s a decent comparison, thx. The Rialto’s use two UCD250LP’s and should be good for 200W into 4ohm all day. I use it with Dynaudio Contour Sr’s now which are also 4 ohm and It doesn’t break a sweat. Seems to perform much better then the ICE powered Wyred4Sound mINT I had before. I’ll look for now rare Maggie dealer, maybe I can take a set home to demo, just not sure about on the wall though.
You make great points, what would be your recommendation for the Martin Logans as they dip down to 1ohm apperantly? I am currently battling it out between some Maggie's 1.7 and Martin Logan ESL X, hard decision, the magnepans makes some instruments sound almost real and the logans make other instruments sound real. But the Eslx give u some concert level spl they are even kinda dangerous if u don't check the volume b4 hitting play. Thanks in advance
I can’t comment on the Maggie’s as I don’t own them. But I am driving a pair of ML ESL-X’s without comprise using the Hypex Buckeye Amp Nc502mp amp build. Drives my ESL-X’s far beyond any Amp I have ever used. When I switched from an Emotiva-XPA to the Buckeye Amp. I re-ran a few REW sweeps. On the XPA amps I had significant drop off below 90Hz and as a result set my crossovers to 90Hz. The Buckeye 502 amp was digging down to 50Hz and only down 3 dB at 40Hz. The ESL-X’s never sounded better. It is true what they say about Electrostatic speakers needing large amounts of power. The Hypex 502 module delivers the power and remains relatively cool. The Emo became a space heater after 30 mins. You can easily look up the specs. Buckeye Amps has a presence here and he has the specs listed. Iirc the Hypex 502 amps are even rated for 2 ohm loads unabridged. Good luck in your selection process.
Oh and Welcome Aboard @DynamicX
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MRC01
Major Contributor
With my Magnepan 3.6/R, max volume (just before the panels start to rattle) measures between 105 and 110 dB SPL and the amp's 1% lights just start to flicker, which means it's putting out its rated continuous power: 400 watts per channel. 400 watts into 4 ohms is 40 Volts and 10 Amps.
This would probably best be discussed in a dedicated thread. Per the ML site the ESL-X is 6 ohms nominal 1.6 ohms min, quite a bit higher than some of their other models (e.g. the 15A dips to 0.5 ohms at 20 kHz). Sensitivity is spec'd at 91 dB/2.83V/m, fairly low and thus need some power if you play them loud and/or sit far from them. The Maggies are less sensitive at 86 dB/2.83V/m which means they require ~3x the power for the same loudness, assuming the specs are accurate (always a matter of some debate).
Maggies are almost purely resistive, with some phase dips around the crossover frequencies, and roughly 4 ohms for most models (dipping to 3 ohms or less at HF particularly with their ribbon tweeter, but again resistive). Most any amp will handle them as long as you have enough power to reach the SPL you want. The three-way design can actually broaden the sweet spot compared to the single large ESL panel, though most ESLs use technology to improve their dispersion.
ESL diaphragms are essentially a big capacitor so impedance dips very low as frequency increases, though due to the transformer signal coupling the HF phase angle actually tends toward inductive in most curves I have seen, with a capacitive dip in the upper midrange that can be challenging. They get away with it for most amps because the signal content is usually pretty low in power at such high frequencies so the amps can handle it. Modern class D amplifiers provide lots of power and are stable into low-impedance loads at high frequency (unlike some earlier models, class D and otherwise), and of course most class AB amplifiers will handle your 'stats just fine. ML's dynamic woofers usually provide more bass than a pure panel speaker like Magnepan though integration has been a challenge over the years (a big deal 20+ yeras ago, but my limited listening in the past say 10 years indicates ML has greatly improved so likely not an issue now).
Sounds like whatever you are using to drive them now is good enough, especially if the ESLs are playing to the point of pain...
FWIWFM/IME/IMO/etc. - Don
Maggies are almost purely resistive, with some phase dips around the crossover frequencies, and roughly 4 ohms for most models (dipping to 3 ohms or less at HF particularly with their ribbon tweeter, but again resistive). Most any amp will handle them as long as you have enough power to reach the SPL you want. The three-way design can actually broaden the sweet spot compared to the single large ESL panel, though most ESLs use technology to improve their dispersion.
ESL diaphragms are essentially a big capacitor so impedance dips very low as frequency increases, though due to the transformer signal coupling the HF phase angle actually tends toward inductive in most curves I have seen, with a capacitive dip in the upper midrange that can be challenging. They get away with it for most amps because the signal content is usually pretty low in power at such high frequencies so the amps can handle it. Modern class D amplifiers provide lots of power and are stable into low-impedance loads at high frequency (unlike some earlier models, class D and otherwise), and of course most class AB amplifiers will handle your 'stats just fine. ML's dynamic woofers usually provide more bass than a pure panel speaker like Magnepan though integration has been a challenge over the years (a big deal 20+ yeras ago, but my limited listening in the past say 10 years indicates ML has greatly improved so likely not an issue now).
Sounds like whatever you are using to drive them now is good enough, especially if the ESLs are playing to the point of pain...
FWIWFM/IME/IMO/etc. - Don
Using crown xls1502 but I notice some hiss at zero volume ,it's super powerfull but instead of getting a second one to run the subs on separate amp with Daytons 8ch Dsp of the minidsp flex , the Buckeye recommendation is looking good as it's not overpriced for a 4 channel model, any other 4ch recommendations similar to buckeyes? the only thing I'm wondering If I should hold of till we get some Nilai500 based amps,
thanks ,
Pro amps like the Crown in general have different gain structure and lower SNR than typical consumer amps. I have one Buckeye NC252MP-based amp (for my overheads), and a couple of Emotiva amps (class AB, old Gen1 models), so I am the last guy to ask about audiophile amps. In addition to Buckeye, amps I would look at for myself include ATI (they have class D and AB), Benchmark (pricey but superb performance, two channels), Bryston (expensive old-school amps, look for used), Sanders (a number of folk pair a Magtech amp with their Maggies and he also has an ESL version, again more expensive), etc. There are so many good amps available now it's hard to choose. I used a tube amp (ARC) on my Maggies for a long time, but I personally do not recommend a tube amp on ESLs due to their changing load impedance. Opinions vary.
I expect you do not need a huge amp as you'll end up overdriving the panels. I suspect you are nowhere near pushing the power limits of the Crown. You can look at an online calculator to get a ballpark for what you might need, and I'd look at the 4-ohm power ratings for the Maggies or the MLs. E.g. http://myhometheater.homestead.com/splcalculator.html will give you a rough idea of how much power you need. 80 dB average SPL is very loud to me; YMMV.
There is always going to be The Next Big Thing coming. If your current amp is powering them to levels plenty loud enough, I would not be in a hurry to spend money. If you must get rid of it, PM me and I'll tell you where to send the check.
HTH - Don
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