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Harshness in upper frequencies in my Maggie 3.7s

67.161.34.228
Posted on December 5, 2016 at 10:29:41
TGR
Audiophile

Posts: 3002
Location: No. California
Joined: March 22, 2004
 I have had my Maggie 3.7s for at least 4 years - maybe 5. (I keep think about upgrading them to 3.7i's but haven't gotten around to it).

For the past 2.5 years they have been driven by a Classe SA5300. (I started with a Simaudio I7, but when I moved and then went to a multichannel system I went to the Classe).

The Classe has twice been back to the factory for blown channels. Fortunately under warrant, and in fact Classe has extended the warranty, although the reason for the blown channels has never really been proven.

The first time this happened, basically the amp just stopped working. But the second time a large amount of high frequency noise went through the Maggies. It was ugly, truly ugly, to hear this.

Well, they still work, and the Classe is back - but there is a harshness in the upper frequencies that just wasn't there before. The harshness is apparent with louder sounds - choral music, large orchestral, even when someone is playing piano chords at forte sounds. There is a kind of sandpapery quality to the sound, if you know what I mean. This happens with multiple sources - both LP and SACD/CD.

The dealer suggest that I replace the fuses, which apparently degrade over time - I did that, and actually it was a little better - but still noticeable.

Would it be possible for the tweeters to still work, but be slightly damaged? I guess this could be amp break-in too, but it really wasn't like this the first time a channel blew, so I am thinking there is a speaker issue.



 

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RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 5, 2016 at 12:19:18
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 What changed was the amp so where the problem is is probably the amp. The high freq edge can't be produced so much by a damaged tweeter unless you managed to tear its suspension without tearing the ribbon (not that common- the ribbon normally goes along and breaks too) - in which case you should readily see it as a swirly tweeter ribbon loose in its "cage".

The amp may have had signal path components replaced, like output transistors. Those will start out sounding overly bright. But in this design the amps should start sounding normal within 100 hrs.

The amp does not have a rating into 4 ohms and no current peak spec (the one derived from voltage may not hold into lower loads) - while I am sure it can do something like 600W at 4 ohms, I think that if it could sustain that without thermal overload and damage then they would have provided a spec for it on the spec sheet.
If you want Classe sound then you can us a pair of bridged DR-9 or model 10 or 25.. Those ancient amps were built to withstand very low loads in a unique bridging topology for the time.

The other thing is that if they spotted thermal damage then they may have turned down the class A bias of the amp, in which case it would be operating in class B from much lower volume levels, which would sound precisely like what you describe.

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 5, 2016 at 12:32:01
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 I think the problem lies with the amplifer (CA5300, not SA ?) not being a good match for the speakers. The MG-3.7 has an impedance dip around 450 hz going down to 2 ohms (refer to solid blue line).

This is probably why your amp went ka-pooey - most likely related to the volume and source at the time. The manufacturer gives this warning "Specifications for output into 4 ohms are omitted because the AC Mains/power supply cannot support all channels driven simultaneously at this level, which would require over 5,000W and only occur under a special test condition. The amplifier easily drives lower impedance loads." If the amp cannot support 4 ohms, it certainly will have problems at 2 ohms.
The harshness is probably clipping.
The tweeter for the 3.7 and 3.7i is identical - in fact the innards of both speakers is the same -- so "upgrading" to the 3.7i will not solve the issue.




"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

Hi Satie!, posted on December 5, 2016 at 12:36:21
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 Obviously neither of us has anything meaningful to do, other than hang out on the forum. We both posted the same thing at the same time.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Hi Satie!, posted on December 5, 2016 at 13:22:58
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Yes, stuck in the WC for a while. Nothing better to do under the circumstances.

 

Thanks, but I don't think you guys took everything into account, posted on December 5, 2016 at 14:03:25
TGR
Audiophile

Posts: 3002
Location: No. California
Joined: March 22, 2004
 First, I have been running the Classe amp and Maggies together for almost 3 years. I have never heard this sound before, not until the Classe went back into my system - about a month or so ago.

Secondly, I had extensive discussions with Classe and the dealer on compatibility. Not once did Classe indicate that the speakers might be at fault for the fact that the Classe blew (they did want to know more about the speaker cable, but finally signed off on that-Classe's conclusion was that either the cables weren't properly mounted or that I simply play music too loudly (seems odd when you have 300 watts per channel, in a normal sized room).

Third, my dealer, who is the only Maggie dealer in the SF Bay Area, sells a lot of Classe/Maggie combos. In fact, when I auditioned the Maggies, the amp was a Classe, and I would have never purchased the Maggies if I had heard this sound.

Of all of this, the most important is that for the three years I have been running this to now, I have never heard this kind of sound. The only variables could be:

1. They somehow changed the amp; or
2. There is now a problem with the Maggies.


 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 5, 2016 at 15:08:12
grantv
Manufacturer

Posts: 7724
Location: B.C.
Joined: January 15, 2002
 My guess is the amp caused some damage to the speaker. Easy to find out; swap in another amp and try.

 

RE: Thanks, but I don't think you guys took everything into account, posted on December 5, 2016 at 16:47:14
DrChaos
Audiophile

Posts: 2063
Location: San Diego
Joined: July 13, 2009
 There's another possibility---when the amp blew it damaged another electronic component in your system. Or even, there is some other component which is at fault for blowing the amps and is continuing to act-up.

It's not really evident how such a problem would manifest itself in the speaker like you hear it, though blowing the crossover is possibility it seems very unlikely. It seems as though the speaker fuses would have certainly blown in that event.

Is it in both speakers? Both channels?

Try different sources. Try something going straight into amplifier with minimal processing other than maybe passive volume.

 

RE: Thanks, but I don't think you guys took everything into account, posted on December 5, 2016 at 17:10:53
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 The next step is to try another amp - either another Classe or a different amp altogether with sufficient power and rated at 4 ohm. I would ask your dealer for a loaner (I miss having a brick and mortar audiophile store near me).





"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 5, 2016 at 19:22:49
Utley1
Audiophile

Posts: 1609
Location: NYC
Joined: July 30, 2010
 Are these the Classe products now made in China? Also try an inductor 3555 which many us use. But it is the amp. on my 1.7's(no ribbon tweeter) I too can get harshness in choral recordings reprocessed digital that were made before the 1990s I use solid state equipment. I believe Grant's stands would also make an impact if you have the space.

 

RE: Thanks, but I don't think you guys took everything into account, posted on December 5, 2016 at 20:29:15
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Considering the history I think your amp has been overdriven for too long and has suffered heat damage that require further repair. That, or they lowered the bias current to avoid further problems and thus degraded the sound of the amp. Tell them and ask for them to have it repaired further.

You should just face the fact that one of two things has been going on
1. You have been playing louder than you think, and routinely driving the amp to its thermal dissipation limits. Playing a 3.7 loud in an average room requires ALLOT of power. I usually suggest something rated for 1kw at 4 ohms and stable into 2 ohms. I suspect the amp is just not quite right for the speaker. It would have been good if you were using 4 channels to biamp (not possible with a stock 3.7). But the reality is that it is an (very) insensitive speaker and yet capable of going very loud. So you are unlikely to tell that you are straining your amp till it goes up in smoke.
2. The particular amp you got was a dud - in any case, if it wasn't it is one now after another round of repairs.

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 6, 2016 at 00:21:44
JBen
Audiophile

Posts: 3082
Location: South FL
Joined: May 18, 2008
Contributor
  Since: July 26, 2010
 In the old days when fine audiophile stores still survived in some suburbs, ending circa 2008, there was one that carried Classe nearby. Something scared that dealer and he dropped the line in 2007. The impression I got was that he primarily was no longer liking their repair services.

I think that a problem which many high-end "honest" factory repair shops have, is finding the original replacement parts. For example, some power transistor are almost custom-made, or at least are batch-produced for given amplifiers. Often, only finite amounts of these are kept for replacements along the years. Furthermore, in many cases these transistors need to be closely pair-matched for top performance. In such dearth, whatever can be found will have to do; unfortunate thing as it is.

I've seen cases of this issue in other fine brands. Thus, it would not be too surprising if Classe is no longer being able to bring your amp to its full original glory. In fact, your description "kind of sandpapery quality to the sound" was exactly right in a couple of cases I've heard. And no amount of warming up time would really fix it.

So, among the other great suggestions, keep in mind the ones that encourage you to haul in a borrowed amp to test with.

Then again, I've used SACD 1812 cannons to make the xover caps in some old Maggies sound "ugly, truly ugly, to hear"...but let's be positive :)

Good luck!

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 6, 2016 at 10:48:07
Norman M
 I never gave a second thought to playing Telarc's first 1812 cannons really loud, even on LP before the CD was available. I used an Adcom GFA-555 to drive Tympani 1Cs (I owned two 555s, so I often bridged them to provide two monoblocks). IAE a flame, smoke and smell came out from one of them. Adcom repaired it free of charge, as I never admitted to my foolishness. Thereafter I never played those cannon shots loud again. After repair the 555 was as good as new, I think most likely they junked the entire chassis and put a new 555 into the original case. I enjoyed those Adcoms in a number of applications, even using a pair of bridged 555s to drive a Tympani IV-A. Yet I replaced them with a pair of Bryston 7B-STs and learned that the Adcoms weren't far behind in their performance. I still have and use those same bridged 555s to driving MMGs in a HT set-up. They have stood the test of time, and not looking for trouble I never did anything to restore them.

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 6, 2016 at 22:23:42
Roger Gustavsson
Audiophile

Posts: 2054
Location: Huskvarna
Joined: February 12, 2010
 neolith,

What speaker is the dotted line in your graph?

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 7, 2016 at 08:10:32
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 The dotted lines are my attempt at an equivalent parallel crossover for the 3.7. Not too shabby. Unfortunately the accompanying Bode diagram has a broad rise from 100 to 1000 hz peaking to +6db around the bass-mid crossover point (400 hz) despite close matching of the individual filters. I have mention this before and find it very frustrating and it has turned me away from biamping my 3.7i.
The solution might be either to use an equalizer or perhaps to go to the digital realm with a DSP - neither of which appeal to me.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 7, 2016 at 10:34:06
Roger Gustavsson
Audiophile

Posts: 2054
Location: Huskvarna
Joined: February 12, 2010
 What about that additional capacitor shown in some schematics of 3.7i, is it there or not?

 

RE: Harshness in upper frequencies in my Maggie 3.7s, posted on December 7, 2016 at 20:52:04
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 Someone else in Sweden asked me about it. I examined my 3.7i before publishing the schematic. What's in the speaker is what's in the schematic - no extra cap that I know of.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

borrow a different amp. That is the only way you can find out if it is the amp. , posted on December 13, 2016 at 17:48:46
Smelly_Socks
 Since you have listened to the combo for years, and now it is a problem..
It could be something in the amp.
The only way to be sure is to borrow a different amp.
Odd if it is BOTH CHANNELS.
Is it? or just one channel?
Both speakers? Or jut one speaker.

If it is both channels, I would suspect power, AC power.
Anything change in your AC lines? or in the neighborhood?

When I bought my Magnepan 3.6 I wanted a Classe amp too. My dealer sold Bryston and Classe, but he was yelling at me to NOT buy a Classe.
(I had known him a long time 30 years... He said repair is a PITA with Classe, vs easy with Bryton. I bought the Bryston.???)

 

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