Amp recommendation for Maggie 3.7i, opinions welcomed

[Blumlein 88]

There's always the option to say you didn't have the gear at the time to perform the proper measurements. Or simply say nothing.

I did have gear for some measurements. I was dabbling in speaker building and did measure impedances of speakers including phase angles. I also could do basic low power FR measures. Had an Oscope too. The listening however was basic long term sighted listening even if informed by some delving into the electronic capabilities.

Obviously I didn't decide to say nothing.

 

[Wombat]

So is this a science forum or subjective haven?

QED

You seem to think that subjectivity is not subject to scientific rigor. So innocent you are.

 

[audimus]

I got to hear the PA-7 and PA-5 Nakamichi amps. Mostly the PA-5.

Yeah, those were some amazing amps, still way over my paygrade at the time. How did you land up listening to all of these great and expensive amps?

 

[Audiocrusader]

I propose a new rule. anyone who makes a subjective slip, gets a "closet subjectivist" banner under their monkier.

 

[Blumlein 88]

Yeah, those were some amazing amps, still way over my paygrade at the time. How did you land up listening to all of these great and expensive amps?

Back in those days I had a circle of audio friends who introduced me to their circle of audio friends and we often got together for listening and socializing sessions. Plus I became friends with an owner of a local high end emporium. He would sometimes loan me traded in gear. Some of the friends were pretty heavy into DIY gear, some in vintage, some in the latest and greatest. Plus I was an audiophile nerd I suppose.

As one of those friends used to say, "hey all of us together can put together a pretty good sounding system". We often took gear from one place to another involving pretty much everything other than speakers. Sometimes if we had something really impressive, once the new wore off, we might loan it to one another for a couple weeks at a time. Seems to me that was more prevalent in years past or at least it was for me.

 

[Blumlein 88]

Can you elaborate further?

Yes it sounded very slightly dark, rather than see through transparent.

It also had a very slightly down response in the upper octave. I've noticed with microphone preamps and such, a surprisingly small tilt in response with careful comparisons can seem a little lighter or darker than accurate. It also had a rising output impedance at higher frequencies. The two go together somewhat. With ribbons tweeters, and ESL (usually what I had), lower impedance in the treble would depress the response in the upper octave a little more. So it likely was audible even if tested blind. Though I didn't have a way to do that at the time.

 

[Wombat]

I propose a new rule. anyone who makes a subjective slip, gets a "closet subjectivist" banner under their monkier.

You are only saying that because you will get the most banners.

 

[Hayabusa]

So I've temporarily and inadvertently hijacked a couple of threads, so I thought I'd start a new thread to get some input. I'm ampless right now, so I need to order something soon. I'm driving Magnepan 3.7i.

Candidates:
Benchmark AHB2 (190 clean watts in to 4 Ohm, max 29A/channel)
Apollon's Purifi (275 or so clean watts into 4 Ohm, max 25A/channel)
Apollon's Hypex NC1200 (500+ clean watts into 4 Ohm, 38A/channel)
All good with 2 Ohm loads, the NC1200 even more so.

From the 3.7i manual:

Caution
The terminal plate states a maximum fuse value of 5 amps Type 3AG ("normal" or
"fast blow") for the midrange and 2 1/2 amps for the tweeter.

Seems all amplifiers you mention can easily blow the fuses for mid/high

 

[DonH56]

Good grief.

There are a lot of things on the Magnepan website that I do not fully agree with, ranging from outdated experiences to technical explanations more marketing than engineering. But it's a really cool company, you get to talk to key players if you give them a call, and I like their sound.

Twenty years ago, and even ten, class D amplifiers had a lot more issues with low-impedance and reactive loads than they do these days and a number of them measured and sounded worse than their AB competition. That is hardly true today; essentially only the cheapies that are poorly designed have issues. And Maggies are a low but relatively benign load. The problem I see more often is AVRs that cannot sustain the power needed to play them very loudly in a large'ish room.

The ribbon tweeter in particular dips low in impedance but all the plots of Maggie impedance for all models over many years has been similar. Some dips around the crossover(s) with relatively broad and mild phase variation. As for experience, I first heard them in 1978, got my first pair in 1979, upgraded in 1988, listened to many along the way and since then. I worked for a couple of Magnepan dealers, helped install them, test them, mod them, repair them, etc. I have heard them with dozens of different amplifiers, tubes, SS, class A, AB, G, H, and a few class D, and did not notice any significant difference in sound with any of the newer crop of class D amplifiers compared to other SS amps. Bass sounds better to me and highs essentially unchanged.

ESLs are a much bigger issue as the impedance dips at HF and has a high phase angle. But a lot of conventional designs are as bad or worse, particularly in terms of the range of impedance magnitude which is often enough 4:1 to 10:1 or more.

As for blowing fuses, many have done it (and with many a speaker), but there is normally far less power in the midrange and treble region, so unless you are very exuberant fuses should not blow. You need all that power for the bass region which can easily demand 10x to 100x the power of the midrange to sound the same. If you are worried about sending all the amplifier's power to the tweeter then do not buy more than say a 12 W amplifier but don't complain to me about the lack of bass and volume.

FWIWFM - Don

 

[DonH56]

Yeah, being a nominal 4 Ohm load, they're only 83db/W/m efficient, so they need some juice.

Magnepan specs 83 dB/m but using 2.83 Vrms (they also spec it at 500 Hz instead of the more common 1 kHz) and not 1 W. Note 2.83 Vrms is actually 2 W into 4 ohms; they claim the directivity of the dipole design gets you that 3 dB back. I do not really disagree with that, but rating the sensitivity that way makes them look better compared to other speakers -- 80 dB/W/m is getting down there. Note 3 dB is a doubling in power.

 

[tensor9]

Magnepan specs 83 dB/m but using 2.83 Vrms (they also spec it at 500 Hz instead of the more common 1 kHz) and not 1 W. Note 2.83 Vrms is actually 2 W into 4 ohms; they claim the directivity of the dipole design gets you that 3 dB back. I do not really disagree with that, but rating the sensitivity that way makes them look better compared to other speakers -- 80 dB/W/m is getting down there. Note 3 dB is a doubling in power.

They are actually specced at 86dB/2.83V/m. At 4 Ohm nominal, that puts them at about 83dB/W/m.

The main guidance I wanted was with respect to power. When I had 1.7i, in had a 300 W ICE based amp. I upgraded to the M700 monoblocks and noticed a significant improvement in bass. This experience leads me to want to stay with higher powered amps even though I would love the better measuring ones. The NC1200 module is no slouch, but there are better...

 

[maty]

They are actually specced at 86dB/2.63V/m. At 4 Ohm nominal, that puts them at about 83dB/W/m...

It is right. Sensitivity is always at 8 Ohms. That is why it is so important to know the impedance / phase graph, its minimum impedance and where it occurs. When estimating the necessary power, it must be taken into account to never fall short of power without falling into exaggeration.

Here we can estimate: https://www.doctorproaudio.com/content.php?2273-calculators-proaudio-sound-dmx&langid=1#calc_spl

But it is only with 8 Ohms speaker. We need to double the power required if the speaker is really 4 Ohms. And double again if it has a minimum of 2 Ohms (woofer band).

More power -> more current -> more heat to dissipate, specially some SMPS. Fans.

 

[DonH56]

They are actually specced at 86dB/2.63V/m. At 4 Ohm nominal, that puts them at about 83dB/W/m.

The main guidance I wanted was with respect to power. When I had 1.7i, in had a 300 W ICE based amp. I upgraded to the M700 monoblocks and noticed a significant improvement in bass. This experience leads me to want to stay with higher powered amps even though I would love the better measuring ones. The NC1200 module is no slouch, but there are better...

Technically 2.83 V, not 2.63 V unless they made a typo. I just used the number you provided (83 dB/W/m); AFAIK they are honest in using xx dB/2.83 V/m and not specifying xx dB/W/m. Whatever.

 

[Deleted member 2944]

They are actually specced at 86dB/2.63V/m. At 4 Ohm nominal, that puts them at about 83dB/W/m.

The main guidance I wanted was with respect to power. When I had 1.7i, in had a 300 W ICE based amp. I upgraded to the M700 monoblocks and noticed a significant improvement in bass. This experience leads me to want to stay with higher powered amps even though I would love the better measuring ones. The NC1200 module is no slouch, but there are better...

It's probably worth running an impedance sweep on the speakers so you know. The plot you posted is, I believe, a simulated one based on second-hand descriptions of the speaker crossover network and transducer resistance.
If you're not aware, all of the recent X.7 Magnepan speakers switched to a series crossover network vice the older parallel networks. The impedance magnitudes are still pretty low, but the phase angle is now somewhat more benign.

I'm not sure why your PSAudio ICE amplifiers wouldn't work okay with these speakers. The 2 ohm portion of the impedance plot is in a narrow range, I'm sure. These are still nominal 4 ohm speakers.

Dave.

 

[tensor9]

Technically 2.83 V, not 2.63 V unless they made a typo. I just used the number you provided (83 dB/W/m); AFAIK they are honest in using xx dB/2.83 V/m and not specifying xx dB/W/m. Whatever.

2.83, typo on my part

 

[Frank Dernie]

I propose a new rule. anyone who makes a subjective slip, gets a "closet subjectivist" banner under their monkier.

Obvious trolling is obvious. Obviously.

 

[Ratatoskr]

If a Pass Labs X250.8 is not affordable and you are open to Class D maybe try a pair of D-Sonic M3a-1500M monoblocks. They have a 30 day in home trial. You can read a review of the predecessor M2-1500M model at 6moons here.

 

[raindance]

I'll admit that I haven't tried a lot of class D amps on my Maggies (.7 and 1.6), but I've tried the Crown XLS series units and the ClassDAudio CDA254. Both sounded truncated, rolled off and thick in the treble with poor cymbal decay. My ancient Adcom GFA5400 solidly trounces both and has great treble detail (it is known for being dark sounding, but this not so with the Maggies) and my old Parasound HCA1500A has the most balanced sound overall with better controlled lows. So I'd probably recommend the Parasound A21, seeing that it is a newer incarnation of what I have.

 

[tensor9]

It's probably worth running an impedance sweep on the speakers so you know. The plot you posted is, I believe, a simulated one based on second-hand descriptions of the speaker crossover network and transducer resistance.
If you're not aware, all of the recent X.7 Magnepan speakers switched to a series crossover network vice the older parallel networks. The impedance magnitudes are still pretty low, but the phase angle is now somewhat more benign.

I'm not sure why your PSAudio ICE amplifiers wouldn't work okay with these speakers. The 2 ohm portion of the impedance plot is in a narrow range, I'm sure. These are still nominal 4 ohm speakers.

Dave.

They were fine actually. I’m just selling off my PS Audio stuff, so I need another amp.

 

[Burning Sounds]

Good grief.

As for experience, I first heard them in 1978, got my first pair in 1979, upgraded in 1988, listened to many along the way and since then. I worked for a couple of Magnepan dealers, helped install them, test them, mod them, repair them, etc. I have heard them with dozens of different amplifiers, tubes, SS, class A, AB, G, H, and a few class D, and did not notice any significant difference in sound with any of the newer crop of class D amplifiers compared to other SS amps. Bass sounds better to me and highs essentially unchanged.

FWIWFM - Don

Wow, Don - my history with Maggies is so similar - bought my first pair in 1979 (still have them), my MG2.5rs were built in 1988 although I bought them used in the 90s. I've driven them with tubes (Beard P100), Class A (Denon, can't remember the model; Mosfet (Nikko Alpha III - remember them?), QSC pro amps Class G or H I think, class AB - Audiolab and Nakamichi (Emotiva) and most recently class D (Apollon Hypex). I've repaired them (including ribbon replacement), biamped them, reframed them. Although they are no longer my main speakers I still have a soft spot for Maggies.

Your description is spot-on and characterises them perfectly IME.