MOSS FETT amps

amplifiers, receivers and loudspeakers
rbbugs
member
member
United States of America
Posts: 59
Joined: 29 Apr 2011 00:37
Location: Lakeside oregon

Re: MOSS FETT amps

Post by rbbugs » 18 Jul 2018 18:40

Thank you guys, I appreciate the input. Leg pulling is fun as long as you get around to the subject, rather sooner than later. As I am rebuilding my speakers it will be a while before I get to hear this amp perform.

cats squirrel
long player
long player
Great Britain
Posts: 2302
Joined: 16 Dec 2008 17:13
Location: Glorious Devon, UK

Re: MOSS FETT amps

Post by cats squirrel » 18 Jul 2018 19:01

AsOriginallyRecorded wrote:Thank you aardvarkash......it is a decent piece of audio equipment...not for the purists, but then again, purists are really chasing their own particular squirrels...
Hey, what are you saying?

I'm building what will be my last amplifier, and it is one with FET output transistors, the ones designed for audio. Design is Indian, and super symmetrical, with current feedback.

I listen mostly to classical music (well Baroque, mostly), where 'pure' is king. That is why I chose a design using Lateral MOSFET's. Two amplifier boards per stereo channel, feeding two mid range units per channel (one with a real ribbon tweeter).

justjed0001
member
member
United States of America
Posts: 122
Joined: 05 May 2018 00:37

Re: MOSS FETT amps

Post by justjed0001 » 19 Jul 2018 00:39

The two most important things in an amp are the power supply, followed the circuits. In stereo, you should have more than enough clean power for almost any reasonable pair of speakers. I'd try to stick to 8 ohm speakers, but it isn't mandatory. Other than that, have fun with it.

As I said in post #3, I like the MOSFET sound, if it's done well. I've been using a 1981 Soundcraftsmen A2502 MOSFET amp in my main system for at least 15 years, and it's the only component that hasn't changed at least twice.

Audie
senior member
senior member
Posts: 647
Joined: 17 Nov 2003 04:55
Location: Australia

Re: MOSS FETT amps

Post by Audie » 23 Jul 2018 18:06

My Perreaux PMF2150B Mosfet amp has been with me since mid 1980, and has since been reworked with premium parts. It compares very well against the best of my other 6 amps.

jusbe
senior member
senior member
Great Britain
Posts: 429
Joined: 15 Jul 2002 00:00
Location: Yorkshire.

Re: MOSS FETT amps

Post by jusbe » 24 Jul 2018 22:45

The Sirius (GamuT) D-200 is a stupendous amp. Now way out of my price range, I wish I had bought one when it first came out!

rbbugs
member
member
United States of America
Posts: 59
Joined: 29 Apr 2011 00:37
Location: Lakeside oregon

Re: MOSS FETT amps

Post by rbbugs » 23 Oct 2018 19:36

this receiver tends to run hot, the fan is controlled by the receiver and doesn't come on until it is really hot unplugging it causes the receiver to shut down so I can't bypass the plug as far as I know. Is there a way to bypass the receiver control so the fan will always run? The other option I am considering is to mount a fan or 2 to the top and power them separately.

ChrisfromRI
senior member
senior member
United States of America
Posts: 259
Joined: 13 May 2004 04:17
Location: New England

Re: MOSS FETT amps

Post by ChrisfromRI » 24 Oct 2018 05:29

Some of the best sounding amplifiers do normally run "hot". The question is just how hot is the heat sink getting, in degrees? Can you measure it with a laser temp gauge? If not, how hot is it to the touch? Can you hold your finger on it or must you pull your finger away? If it seems so hot it will burn your finger then put a drop of water on it and see if the water boils (212F). If it doesn't boil then it's under 212F or 100C which really is not too hot. If it boils it is over that and might indeed be too hot. Is there enough open clearance space for air circulation around the unit? Would adding some more open space Help it run cooler?

cafe latte
vinyl addict
vinyl addict
Australia
Posts: 10263
Joined: 11 Oct 2009 04:27
Location: Cattle property near Ravenshoe Qld Australia

Re: MOSS FETT amps

Post by cafe latte » 24 Oct 2018 07:18

http://sound.whsites.net/project101.htm
Mosfet and possibly the best amp I ever heard,
Chris

JoeE SP9
long player
long player
United States of America
Posts: 4634
Joined: 23 Feb 2009 20:20
Location: Phildelphia, Pennsylvania

Re: MOSS FETT amps

Post by JoeE SP9 » 24 Oct 2018 20:06

Any recently and competently designed MOSFET amp should not be afflicted with "MOSFET mist". Nelson Pass uses MOSFET's for Pass amplifiers. They don't have MOSFET mist.

rewfew
long player
long player
Posts: 1039
Joined: 08 Mar 2009 17:50
Location: Kansas City Missouri

Re: MOSS FETT amps

Post by rewfew » 28 Oct 2018 16:44

I've been using an early mosfet design since the mid 80's. A Hafler DH220. Look around the net, it's a well praised venerable piece of audio design. And circuit design is the key to it's validity. A nice review with gobs of test measurement on the original DH200 which the 220 improved upon. https://kenrockwell.com/audio/hafler/dh-200.htm

katana1100
senior member
senior member
Posts: 618
Joined: 14 Dec 2011 00:23

Re: MOSS FETT amps

Post by katana1100 » 28 Oct 2018 17:35

“MOSFET mist” is as real as “ clogging “ that some happens with the technics 1210 ( despite its perfect speed )
I have two mossfet amps I used sometimes
Hafler xl280 and nad 208.
The xl280 is a great amp, they can be found cheap .
The 208 is a powerhouse, can put out 1000w peak into 1ohm load.
I have acoustat 2+2, these amps can drive these with ease. Modern non mosfet amps ( like the Emotiva amps) will shut down.

gnuyork
member
member
Posts: 91
Joined: 26 Sep 2014 12:57

Re: MOSS FETT amps

Post by gnuyork » 05 Nov 2018 18:03

I use a Adcom GFA 5500 which is MOSFET I believe. I don't have much to compare with but I think it sounds fantastic since I've had it recapped. I use speakers with ribbon tweeters and an old Dual turntable with a Denon cart.

justjed0001
member
member
United States of America
Posts: 122
Joined: 05 May 2018 00:37

Re: MOSS FETT amps

Post by justjed0001 » 05 Nov 2018 23:56

Come on, guys! A MOSFET is just a transistor type. The circuit, HOW that MOSFET is used, is what makes the difference. Good MOSFET designs are quiet, fast, and reliable. So are good tube circuits. And good bipolar designs. And good chip designs, etc, etc. They all have advantages, and disadvantages. But, all you really need is a good quiet power supply, and a GOOD circuit design. Everything else is a feature.

cafe latte
vinyl addict
vinyl addict
Australia
Posts: 10263
Joined: 11 Oct 2009 04:27
Location: Cattle property near Ravenshoe Qld Australia

Re: MOSS FETT amps

Post by cafe latte » 06 Nov 2018 00:15

justjed0001 wrote:
05 Nov 2018 23:56
Come on, guys! A MOSFET is just a transistor type. The circuit, HOW that MOSFET is used, is what makes the difference. Good MOSFET designs are quiet, fast, and reliable. So are good tube circuits. And good bipolar designs. And good chip designs, etc, etc. They all have advantages, and disadvantages. But, all you really need is a good quiet power supply, and a GOOD circuit design. Everything else is a feature.
Mosfet are generally very reliable more so than transistors due to the self protecting nature of mosfets. I prefer a good mosfet design over transistors. Yes a Mosfet is a type of transistor (FET) but it behaves quite differently too.
https://en.wikipedia.org/wiki/MOSFET
Chris

justjed0001
member
member
United States of America
Posts: 122
Joined: 05 May 2018 00:37

Re: MOSS FETT amps

Post by justjed0001 » 06 Nov 2018 01:26

Just pointing out that there are many ways to build a good amplifier. I like tubes, so I have a couple of 12ax7s in my pre-amp, and I like what a good MOSFET design does with that signal. But that's just me...