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Infinity F.E.T. preamp

I am getting up in years and don't spend the time listening as much as I do playing my drums and guitars. I have an Infinity F.E.T. preamp (blue) S/N 173. It has a slight background hum and I am not inclined to put money into it. Anybody have an idea what it might be worth as is, or will it be worth getting all the bugs worked out prior to selling?  I'm torn because I have yet to hear a better preamp (yes it blew away my SP-6). I now run a Marsh Audio P2000., because of the hum issue in the FET. The Marsh is close in character, but just doesn't do the sound-stage quite as well. Now on a limited income I face reality. The Marsh is close close enough to my old ears, and I hope to pass the FET off To someone who will really appreciate it.

Thoughts?

B


machdude
12 responses Add your response
Post removed 
jperry
2,450 posts
 
Since my prior post was deleted...

The Infinity FET preamp along with its companion piece the Infinity switching power amp are real pieces of hi fi history.

I looked on ebay, kruipen.com, and hifishark.com for sales and there aren't any likely because so few were made. 

Please let me know if you list this for sale.

Jim Perry
georgehifi's avatar
georgehifi
10,312 posts
 
I am getting up in years and don’t spend the time listening as much as I do playing my drums and guitars. I have an Infinity F.E.T. preamp (blue) S/N 173. It has a slight background hum and I am not inclined to put money into it.
This is getting very old probably just a dried up cap, if you or a friend can solder, have a look at the electrolytic caps, look for bulging or dried up brow fluid leakage around them. Cap are cheap. Replace the with the same voltage and microfarad (uF)
BTW they have a polarity made sure the new one goes in the same way
I’ve posted up a picture with the caps to look at circled in red.
https://ibb.co/dwTA3o

It's easy to work on both top and bottom come off no need to take the board out to do the cap replacements.

Cheers George
roberjerman
4,319 posts
 
I saw the FET preamp and Class D amp appear - and disappear years ago (1977?)! Poor marketing? I bought my first pair of Infinity speakers that year - Monitor 1A's.
Post removed 
celander's avatar
celander
1,503 posts
 
@roberjerman
 
I seem to recall the original Infinity class D amp (SWAMP) was unstable. John Urlick of Infinity who designed it went on to form Spectron, which redefined the class D circuitry in his amplifiers with better devices. I own a Digital One amp and love it with my Dunlavy SC-IVa’s. John told me that John Dunlavy voiced his speaker designs using Spectron amps.
Post removed 
analogman70
2 posts
 

Jim,

It's been a few years since I posted this, but I haven't done anything with the preamp. I'll be pulling it out soon to sell it and wanted to offer it to you first as you requested.

 

Bob Specht

boatdrinks77's avatar
boatdrinks77
2 posts
 

Hi Bob  I would be interested in the preamp........ Dan :-)

gunderwood
3 posts
 

Hi Bob,

Did you sell the FET preamp?

Thanks, Gene

voltaicq
7 posts
 

You will definitely be hard pressed to find a preamp under $6k that can perform as well as the Infinity FET, it is still one of my favorite pieces that will always stick around in my Infinity collection (#100 here). Last I saw a couple years ago they were still selling for $2-4000 depending on condition due to rarity. The hum could be a number of things but is most likely the large can capacitor near the AC outlets. The internal speaker relay also tends to have some issues over time, but is a quick replacement. 

lafish3's avatar
lafish3
10 posts
 

I remember that preamp well. We had one at the stereo shop in L.A. where I worked in the late 70s. As I recall it sounded significantly better than anything else we had at the time. 

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