F5 power amplifier

[udailey]

Thanks guys. I listened to the 1.7's recently. I like them a lot.
Uriah

[labjr]

I've heard that the MG 3.6s are awesome with the right amplifier, good cables & proper room treatment. You have to spend a lot to get the best sound out of them.

[a.wayne]

Originally Posted by Macronaut

It really depends on the model. Maggie relies on two basic drivers. The planar panels and the foil ribbons.

The planar panels are relatively inneficient and most people are going to want to match them with the appropriate watts for a similar SPL as they are used to. If a conventional box speaker measures about 87 db efficiency then a full sized Magnepan probably comes in at about 85 db. But that will vary wildly depending on the model. The old SMGa's were well over 90 db efficient but you had others that were more like 82 db. Or lower. Obviously the power requirements can vary greatly.

So... the kind of amplification that will suit them best will depend on the model, your preferences and the room. I very much like their speakers (hope so because I have chosen to make a project out of a pair of 2.6's) and have no problem understanding the attraction. A couple of faults that tend to be common with these speakers (all my humble opinion, of course) is poor crossover performance. And the last couple of octaves of bass is can leave something to be desired. I think that is due to the single ended magnet structure.

Another maker you might look into is Eminent Technologies. They may actually surpass Magnepan's planar drivers. Although I have not heard a set as of yet.

Agree about the planar limitations and the standard x-over is from the local dollar store. The best i have heard 1.6 is on a chip -amp, bel canto ! If setup correctly and have the x-over mods they sound pretty good , for the price a steal . I have heard the ET speakers the Mags are superior IMO ..

I have also heard the new 1.7, the demo by the dealer was just plain bad and was no where as good as the modded 1.6, so I'm not sure if it is better than the modded 1.6 ..

Originally Posted by udailey

Thanks guys. I listened to the 1.7's recently. I like them a lot.
Uriah

Well there's a vote .... now to drive them with your F5 !

[HaflerFreak]

I will most certainly be auditioning a pair of 1990 MG2.6/R's on a F5.

Rated for 87dB sensitivity and 4.7 ohms, I cannot imagine the ribbons will disappoint with an F5, I hear the top-end is supernatural on the F5 - that is also how I could describe those foil ribbons - what a match!

[jacco vermeulen]

Originally Posted by udailey

Any suggestions for a Pass amp that can really move these beasts?

Aleph Uno

[etoiledusoir]

Originally Posted by tinitus

Yes, I guess one pr device would work
But they dont seem very practical to use, with tricky mounting

HEATSINK ALUMINUM EXTRUSION 10.08 WIDE 1-12" PC. - eBay (item 170471042670 end time Apr-17-10 05:06:27 PDT)

Thanks for the tip,

I just bought one piece of the heatsink you suggested. Normally, I would need 2 pieces of those heatsink. But to cut the cost of construction down, I'm thinking to use a alumium plate (12'X10'X (1/2' or 1') ) over the heatsink with thermal grease and the 4 transistors will be installed on the aluminium plate. I can get spare pieces of aluminium at very cheap price at a shop near my home. Will this setup be enough ?

Thanks for you suggestions

[acold7dusta]

Originally Posted by etoiledusoir

Thanks for the tip,

I just bought one piece of the heatsink you suggested. Normally, I would need 2 pieces of those heatsink. But to cut the cost of construction down, I'm thinking to use a alumium plate (12'X10'X (1/2' or 1') ) over the heatsink with thermal grease and the 4 transistors will be installed on the aluminium plate. I can get spare pieces of aluminium at very cheap price at a shop near my home. Will this setup be enough ?

Thanks for you suggestions

Don't forget insulators between the transistors and sink! (mica or similar)

[bobodioulasso]

If i could get aluminium for cheap, i would make heatsinks that way:

[bear]

bobo, that will not make an efficient heatsink for a large size like is needed in this amp... posted a pic back a while in this thread (iirc) of a SE Mosfet DC coupled amp I sold around the time NP came out with the first Zen... that shows a way of DIY heatsinks out of aluminum parts that works well... Altec and Phase Linear did things similarly... fyi.

etoile, adding in a big fat backing plate will add thermal mass, and improve the thermal spread, not bad things at all, but for it to actually work the two surfaces must be flat relative to each other and also held by screws flat to each other... but over time the thermal capacity of that heatsink with a big fat plate on the back will not be significantly increased over that of the basic extrusion itself. It will just take longer to come up to temperature due to the extra aluminum.

So in ultimate terms a shorter not as thick (but as thick or thicker than the heatsink extrusion flat surface) as you propose backing plate will work about the same... all it needs to do is to transfer the heat from the mosfet to the plate to the heatsink with minimum losses...

_-_-bear

[Macronaut]

Originally Posted by a.wayne

Agree about the planar limitations and the standard x-over is from the local dollar store. The best i have heard 1.6 is on a chip -amp, bel canto ! If setup correctly and have the x-over mods they sound pretty good , for the price a steal . I have heard the ET speakers the Mags are superior IMO ..

I have also heard the new 1.7, the demo by the dealer was just plain bad and was no where as good as the modded 1.6, so I'm not sure if it is better than the modded 1.6 ..



Well there's a vote .... now to drive them with your F5 !

I just do not understand why Magnepan sets their crossovers up the way they do. They seem to favor an asymmetric step to the next driver and then flip the polarity. (???. Really?) On top of that the crossover tuning tends to be a sore spot with many of their speakers. To be fair, Magnepan has more than survived where others have long since faded away. So they have to be doing something right.

I'm not so sure that an F5 is going to be a good choice for 1.7's though. The 1.7's sensitivity is 86dB/500Hz @ 2.83v. I do not doubt that you can get some glorious sound with the power that the F5 has to offer. If it suits you then all is well. I just suspect that most 1.7 owners would end up changing out the F5 in favor of something that can push them into the 'happy' zone. Nelson never designed the F5 to compliment Magnepan's. But I do think it would be very nice with a pair of SMG's @ 90 db efficiency. Of course... YMMV.