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-   -   FOSTEX 300 laboratory power amp (http://www.diyaudio.com/forums/solid-state/80712-fostex-300-laboratory-power-amp.html)

cybersniper 1st June 2006 07:25 PM

FOSTEX 300 laboratory power amp
 
Do any oif you have any information about this amp???

I just got one and need some information about it. Any source of tech specs??

Thanks

Eduardo

thejohn 2nd June 2006 05:43 AM

I asked this same question a while back regarding the Lab 600 and never got any replies. I guess these weren't all that common. I have since managed to source the service manual from our local Fostex agent and it covers the 300 as well. Try you local agent if there is one and if you don't have any success let me know and i can get you a copy.

John

cybersniper 2nd June 2006 07:29 AM

I tried the spanish fostex already
 
Thank you for your offer, it is just what I needed. I contacted the spansih fostex imported BEFORE even getting the 300 amp and they knew nothing about it.
They are only involved into digital recording and know nothing and have never imported any power amps.

Are you happy with your amp?

Can you send me a copy of the manual?
if you have any cost tell me and I will send it to you

THANK YOU VERY MUCH
Eduardo

thejohn 2nd June 2006 01:40 PM

Eduardo,

I've sent you an email...

I like this amp a lot. Haven't had it for long - I need to do some repairs to it before any critical listening - someone has replaced some components in one channel so they are not identical.
At first listen it sounds very detailed, quite bright. Serious control of the bottom end. It's really well built, 1.3KVA mains transformer!!!
Some of the transistors are obsolete but a company in USA called consolidated electronics has all of them.
It has a low level hiss which I need to cure which is audible on my 15" Tannoy's but not on less sensitive speakers.
I reckon it's worth spending some time and effort doing some minor improvements.

John

Craig405 9th June 2006 11:03 AM

Hi John,

It must be an obscure amp for noone to reply to your posts :(
Could you send me the manual too?

My address is craigfini@hotmail.co.uk

Cheers
Craig

thejohn 10th June 2006 09:50 AM

I always end up unintentionaly finding (and liking) the obscure stuff! They say you can find info on anything on the net... try googling these amps! :) There seem to be a few arround these parts - mostly out of theatres and cinemas. I was mighty suprised when the local agents said "sure we've got the manual, we'll make you a copy" Craig, I'll drop you a mail shortly. Have you got the 300 or 600?

Craig405 11th June 2006 02:00 PM

TheJohn,

The amplfiier i have is the 600 like yours, just got it off Ebay today at a pretty good price.
Yes the internet has absolutley no information on these amplifiers, its quite suprising.
Speaking as someone who has listened to the 600 how does it sound compared to other hifi amps?

Regards
Craig

thejohn 11th June 2006 04:30 PM

It's really hard to say definitively as I haven't done much side by side comparison. Until recently was running Genelec 1031's which are active. Just finished building boxes for my 15" Tannoy 3836's and suddenly I needed an amp! Used my old Lexicon (made by bryston) for a bit, then was offered a good price and sold it - borrowed my neighbour's old nad 3020i and just used the power amp section. Figured I didn't need much power as the speakers are very efficient. Was amazed at how good the nad sounded!
Got the Fostex - as I mentioned above, it's had some dodgy work done to it so I doubt it's performing optimally - but it's a different amp to the nad. More detail, cleaner tops, huge bottom end control - haven't switched the subs on for a couple of weeks now!
It's my type of amp - clean, clear, uncoloured, some might say clinical, super-detailed. I prefer this to the warm, fuzzy, feel-good amps some people claim is hi-fi. I want every component to be as revealing as posible to defects in the rest of the chain. I'm still going to do some work on the amp and clean up some of the shoddy work, clean up some of the wiring, try and quieten it down a little - joys of sensitive speakers, you can hear any little hum / hiss!
I would like to hear your thoughts once you've had a chance to listen to it... If you don't like it you can always send it to me! :D I'm building a matching 15" centre chanel and will need another amp!

Craig405 12th June 2006 10:18 AM

Im glad to hear you consider the amplifier to have a nice sound.
I really wanted an amplifier with good bass control as my speakers only have 2x8 inch bass drivers each, hopefully better curent delivery will help with their bad bass performance.

I am hoping the amplifier i purchased will be in full working order and have unaltered internals so if you need and info on its guts for your reconditioning i can provide you with it.
The amp was sold to me as untested, i am just hoping if there is a problem it hasnt blown the output transistors, theres a lot to replace!

Sure ill let you know what i think about it's sound, although im sure it will beat the cheap Hitachi HA-3 amp i was using until recently.

Regards
Craig

Craig405 23rd June 2006 09:10 AM

HI,

Ok i received my amp yesterday and have been slowly testing it since.

I have begun to bias it, although i dont trust my multimeter to be calibrated correctly ( i have 3 and they all say different things) :(.
Approximatly what position do your output bias pots sit in for
5-10mA idle current? i think mine is very much underbiased as it came with pots set to max resistance (twisted all the way to the left) and since i dont trust my multimeter im concerned about increasing it.

Just wondered if the smaller transistors ( the ones with the clip on heatsinks) on your lab 600 get quite hot to the touch after a few minutes of idleness? im trying to be very careful with this amplifier theyres too many output transistors for a cheap replacement!

Other than the bias and heat niggles it all looks good.

Regards
Craig


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