No More Semelab Audio FET's

edited March 2019 in Amplifiers
No More Semelab Audio FET's

Sorry Claymore fans, the upgraded Semelab Audio FET,s I used to replace and upgrade Inca Tech Claymore have stopped production.
I have enough to complete the upgrade of the two Claymore's that I am doing now ONLY.

The hopeful news is I think I have found another complementary pair that may work, but a few change will also have to be done to the circuit board to make them run well to my spec.

I have ordered a few of the new one to try out and will publish a good bad notice later.
Mean while all the cap upgrade can still be done.

Best Col


  • Fingers crossed for these substitutes!
  • Me I got everything cross and it ruined my calculator,
  • AntiCrap said:
    Me I got everything cross and it ruined my calculator,
    Then replace its fets!
  • A rolling FET gathers no MOS?

    I get so fetup when components are discontinued?

  • It all to do with charge, and the Miller Effect., So I use a Baker Clamp, Ted seems happy with that. But Columns for the effort, and it can make the Erg of a difference, so Faraday says.
    Maxwell go now to see Quack, going by Tesla and Newton Bus.
  • Great news, well for me the New FET.s out perform the orignals and the SEMELAB FET's.
  • ..,orderly queue begins to form...
  • What for FET,s or the Loo?
  • To tinkle or to tinker
    That is the question
  • No boom or bash is the real question
  • edited March 2019
    Hi Guys for folk like Quickie here is a link to the DATA sheet of the new FET.s

    Link to the DATA sheets for the new FET,s Oh you must change a few other bits to get them to work very well, have fun.
  • The new FET;s out perform the old one by a long way a few mods on the other component and the sound was stunning, two Inca Tech Claymore have had this new mod done and I will with luck be able to post the owners reviews.
    But for the other DIYer here is the part numbers.

    FQA 28N15 & FQA 36P15
  • From Steve on the new FET,s
    "Those of suitable years will most likely know of Colin Wonfor for his various amplifier models and cables over the past few decades. For me that started with the Inca Tech Claymore amp I bought in my early days of Hi-Fi, it replaced the also legendary NAD 3020A. At the time I was using Celestion SL6s and Linn Axis TT later an LP12.

    Back then I demo’d the Naim NAIT, Linn Intek plus something from Exposure. The Claymore blew them all away, it simply was more musical, engaging, powerful and controlled.

    Later is was used with EPOS ES14 before being retired in favour of an original Linn Kairn + LK280 Spark. An upgrade that only really worked once the later improved “Brilliant” SMPS came out for the Kairn. Maybe partly because I had done a few tweaks inside the Claymore replacing the crimp connections with solder joints that improved the refinement, smoothness and musicality to giant killing proportions.

    The Claymore was later passed to my Dad to use, (Axis and Keilidh’s) who enjoyed it for many years. After he passed away I kept it as it always was a favourite bit of kit and a “classic”. 

    Skip to the present, a few weeks ago I dug it out the cupboard as I needed to try out an LP12 I had just assembled with a MM cart. To my dismay the amp crackled from one channel and wasn’t usable. With the lid off all looked okay, so nothing damaged or leaked….yet! 

    I remember seeing post from Colin and others and having the Claymore serviced. Thankfully Colin quickly replied back to my email and after a couple phone calls my amp was on its way back to its designer for repair and upgrades, it seemed to good an opportunity to miss. 

    In went new bigger capacitors, pot, various diodes and resistors then by chance Colin had a some new bigger FETs to hand, not the one that are normally used but some “special” ones. As long as they could be made to fit and tune in they would be great. Wasn’t long before I had another call, all in and adjusted and working….”oh it’s pushing out a constant 80 watts” !!! 

    Over this time, I got to have several discussions with Colin, who is the most charming and sincere of gentlemen who could wish to chat with. The diverse and amazing projects his career has seen him involved in is mind blowing. He is a genius and has invented some amazing stuff, I’ll not divulge the details, a great biography or book is there to be written.

    Part of our discussion lead to his current amplifiers, as seen on the EWA website. Colin offered to build up the little Q20 for me and a friend to try out.

    The Q20 arrived first, so I hooked it up to run in, by a coincidence I had recently bought up a pair of Celestion SL6si, so this was trip down memory lane. Immediately it was apparent this amp was beyond its diminutive size and conservatively rated 20 watts. It had no issues taking hold of the SL6 and driving it to some serious volumes and with grip and control. That probably is what grabs you first and amazes you. How does such a little box have such big balls!! The bass is as tight and extended as pretty much anything I’ve heard under several grand. Let’s put that in perspective this amp is around £750. My “normal” amps are Linn 5125, 2250 Dynamik and Klimax Solo Dynamik. Okay the Solo are a bit special so I didn’t try or expect to compete with them.

    Next I moved the amp to my Lounge where I hooked it up to an Akurate DSM (Katalyst) and PMC Fact 8. Again it had great grip and bass control and extension. Sound was open and very detailed and revealing.

    Friend of mine came over for a listen, he uses a Majik DSM and a 5125, but only 2 channels of it. So I set mine up on the Fact 8 in 2 channel mode as reference. Then set about comparing the Q20 to the 5125 first.

    It revealed a very interesting situation. One I will say is system matching. The Q20 sounds superb, amazing for its size, power and price. That we both had no doubt. Only in comparison to the Linn did the presentation of the two become apparent. The Q20 has I guess you would say an incisive mid band, which with a very clean and some might say lean Fact 8 it perhaps was a little too much of a good thing. The 5125 had a “warmth” or softness to it that initially sounds more pleasing. For me over a longer listen I heard that more as a coloration. There is the dilemma, the Q20 for me is the better more correct amp. Revealing more of the detail in the music, the Linn did what Linn often does and gives you complete rounded performance that had a comfort to it and was also easy to listen too.

    Potential a few cable changes may have balanced it out, or of coarse different speakers. The Fact are a little unique in their presentation, stunning when well matched. That said I believe from listening from various speakers over the years the Q20 will easily match other less “specialist” speakers.

    Comparing to the 2250/D which was an £1800 amp plus a £400 power supply upgrade, it sat between the presentation style of the Q20 and 5125, balancing the incisive detail and warmth. The Q20 was in no way out place in this company, we could easily live with the Q20 amp. Using the Q20 on the Celestion or my Dynaudio Gemini the match is better and more neutral.

    Trying the Q20 on my friend’s system which has some 30-40 year old large 3 way stand mount speakers, built from a design published in magazine back then. Sort of a BBC/Rogers/Harbarth/Celestion type classic design. Again the Q20 was superb, how does some a little box sound so good, so loud, doesn’t get hot and cost what it does? The difference in presentation between the 5125 was still there, but now it was just a difference not an issue, for me was preferable. 

    It left two questions, what the heck does the EWA M50 sound like, which Colin seems very pleased with, then what would the rebuilt Claymore do?

    So back to my room with Fact 8, hooked the Claymore in and used it like a power amp by pre-setting the volume pot to 75% and using the CD in. OMG !!! F’n hell…. It’s got monster gonads !! seriously loud and powerful. Bass power and control that surpassed the Q20, but with a body and tone/warmth found slightly missing from the Q20. (With the Fact8) I found myself leaving tracks playing longer with the Claymore connected, its musical prowess still there after 30+ years, but now with added authority and grunt. As before this is an integrated amp that goes hunting in Pre-Power territories and wins. Plug the best source in you can and hook up any speakers and its going to deliver way above its vintage and price.

    Leaves me to say many thanks to Colin Wonfor, for his insight to many things, restoring an “Ultimate Claymore” and loaning some of his later work. He is a genius and such a genuine gentleman…. The Q20 is superb and a bargain."
  • It’s quite a review portfolio you’ve got these days Colin. :-)
  • It is not bad, just wish I could make better kit, for all to enjoy music as it should be heard, but I am still learning. >:)
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