Hello from Georgia

[thomas_tran]

Hi everyone. I'm Thomas from GA. I own a pair of ML Mosaic 6 months ago from a seller. I'm loving this pair and impressed by their sound quality.

I sign up for this site for better understanding about my speakers. Actually, I have a issue with my speakers and seek for the solution in this site.

Nice to join and meet you guys.

 

[twich54]

Welcome Tom, what's the issue with your speakers ?

 

[Jazzman53]

Welcome Tom,
I'm in GA too... Savannah. What problem are you having with your speakers? I don't know much about ML's (I don't own ML's) but I'm an ESL builder with a basic knowledge of their operation. Maybe I can help.

Welcome to the forum!
Charlie

 

[thomas_tran]

Thank you for your reply and willingness to help me.

I fixed the issues already with help from ML customer service. I must say that the ML customer service is awesome. I'm surprised by their professional service even I didn't buy anything from them. 5 stars for customer service.

Anyway, I want to share my speaker issue with you in case someone faces the same one.

A binding post behind a speaker gets loose. Consequently, sound from the speaker is on and off randomly and noise comes out instead of music. I tried to to tight the loosing post but I didn't know how to. I believed I could remove the front grill and the rear grill and then tight the post from inside the cabinet.

However, the rear grill is attached to the cabinet by several hidden screws. I sent an email to ML customer service for instruction. And surprisingly, they replied and sent me a detailed instruction to handle the task. Another issue came up. I couldn't remove the woofer even I removed all its screws. I think they glued the woofer onto the cabinet. I didn't want to pry the woofer so hard. It may cause damage for either cabinet or woofer.

Another email sent, and ML told me that I can remove the base of the cabinet to tight the post from bottom. Hoorah! I made it, and the sound comes out crystal again. I'm happy now. Next time if I want to upgrade my system, ML will be the first choice.

Now, I have another question about my audio system setup.

The Mosaic specs are kind of weird.

The impedance is 5ohms and amplifier power is recommended 20-350W per channel (loud speaker with low impedance). I followed the spec printed behind the speaker (200watts/5ohms) for sure.

I figured out that it's hard to find a receiver matching this specs. I asked a question on ML fanpage on facebook. I was recommended and I decided to get a YAMAHA RX-V385 5.1-Channel.

I selected 6ohms for receiver and hooked them up (the receiver has either 8 or 6ohms only). They worked fine, but one day I played loud music and the receiver was overheated then it shut down for protection. The whole system is still working later on when receiver cools down. But I'm curious why ML Mosaic specs are so strange (loud speaker with low impedance) and where I can find a receiver which is powerful enough to drive them?

Do you have any recommendation for me?

Thank you guys, and I'm sorry for a long post.

 

[Leporello]

Many people are confused about the issue of "impedance matching". Given a source (i.e. amplifier) with a certain impedance, the maximum power that can be extracted from it is when the load impedance matches the source impedance (technically, the complex conjugate matches, but an amplifier impedance is essentially non-reactive).

A vacuum tube amplifier has a very high impedance coming from the tube plates. In order to deal with this--transfer the maximum amount of power from it--most tube amps use a matching transformer. To get maximum power transfer, and minimum power wasted across the amplifier's source impedance, you use the appropriate tap according to the speaker's "nominal impedance" (most speakers don't have a constant impedance but have a magnitude and phase of impedance all over the map--especially ESL's, which is why they are particularly unforgiving of amplifier performance. So even in that situation, selecting the right tap is at best a compromise.)

A solid state amplifier is a whole other beast. It turns out that, given a load (the loudspeaker) the optimum power transfer occurs not when the source impedance matches, but when it is essentially zero. Most modern solid state amplifiers come close to that ideal.

Adding to the confusion, though, some modern a/v receivers apparently have a switch to select your speaker impedance. I don't know this first hand because I have never owned one, but apparently the switch has nothing to do with the actual source impedance of the amplifier. Instead, it switches the power supply rail to a lower value for the lower impedance, to protect the speaker from being over-powered. Given an amplifier that behaves like an ideal voltage source (which truthfully most a/v receivers don't come close to) a 4 ohm load will suck twice as much power out of it as an 8 ohm load. From what I've read about these impedance switches--and again, I don't know this from first hand experience-- you should just go ahead and run it in the higher impedance position.

For an ESL in particular, you want an amp that behaves as much as possible like an ideal voltage source. That means if it's driven to a certain power before clipping into 8 ohms, that power should double into 4 ohms. Ideally it should double again into 2 ohms, or at least it should be capable of driving 2 ohms without damage or overheating.

So bottom line, and I believe this will be the unanimous opinion of this forum, you should as soon as finances permit get an external power amplifier for your ESL's, and use the preamp outputs of your receiver to drive it. Emotiva makes a stereo power amp for under a grand that should be adequate.

 

[JonFo]

So bottom line, and I believe this will be the unanimous opinion of this forum, you should as soon as finances permit get an external power amplifier for your ESL's, and use the preamp outputs of your receiver to drive it. Emotiva makes a stereo power amp for under a grand that should be adequate.

Great advice for ESL owners, but in this case, the Mosaic uses ATF transducers, so less of a challenge for an amp.
But I will say, even for non-ESL, an external amp of sufficient quality and power will result in better overall results.

 

[twodogs112]

My experience with receivers powering ml and other electrostatic speakers is that you need at least 100 wpc to power them. More is definitely better. The high end Sony es, denon, and Yamaha have worked ok for me. They won’t play loud, or with dynamic music. Just ok. I currently use my Yamaha rx a2000 as a preamp. I use separate amps to power the speakers. For me 200 wpc @ 8 ohms works the best. I don’t think your receiver has enough omph to get them going. Get a bit more power and they will sound great.
Till then , I agree with the previous post. Run them in the 8 ohm output on the receiver you have. Happy listening and welcome.

 

[Robert D]

Great advice for ESL owners, but in this case, the Mosaic uses ATF transducers, so less of a challenge for an amp.
But I will say, even for non-ESL, an external amp of sufficient quality and power will result in better overall results.

Two of those Emotiva monoblocks like I have for my center channel would be great.

https://emotiva.com/collections/amps/products/hc-1

 

[Leporello]

Great advice for ESL owners, but in this case, the Mosaic uses ATF transducers, so less of a challenge for an amp.

If the receiver is overheating and shutting down, though, it is being challenged.

Not sure what ATF transducer means.

 

[JonFo]

If the receiver is overheating and shutting down, though, it is being challenged.

Not sure what ATF transducer means.

Correct, it probably does not like the complex load of the 3-way crossover in the Mosaic. The impedance is listed as 5 Ohms; most receivers struggle with < 6.

ATF (Advanced Thin Film) was a planar-type driver before their switch to the Folded Motion AMT-style drivers. AMT = Air Motion Transformer, pioneered by Heil, whose patents ran out many years ago, and is now made by a bunch of third parties, including ML.

 

[Reverb]

Welcome to the forum, Tom. Enjoy!