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Thread: montesquieu's STA100

  1. #81
    Join Date: Mar 2016

    Location: Barnet, london UK

    Posts: 2,146
    I'm Adam.

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    Yes well said Edward. The synergy Tom has put together to get the most from the music he collects and loves is the key here. Every element is thoughtfully introduced and if it isn’t of the required standard it goes. The Radford STA100 is an endpoint for any system but for Tom’s brew it’s perfect. Perfect is a big word in this game and one should utter it with care, but in this system the word fits. I had my doubts I’d be able to really agree on the justification of extra power the STA100 delivers over the smaller stablemate, the STA25. I have the STA25 feeding Tannoy Monitor Gold 12” in RFC custom cabinets, and quite frankly it just works so well.

    The STA100 delivers music, as said by Edward, with ease and feels so effortless and in control, not that the STA25 doesn’t but this is just something else, something different which is hard to articulate. I said on the day it feels like one of those New big arsed Rolls Royce cars, classsy, big, luxurious with all that power to pull away, and plenty in reserve.
    I haven’t even touched on the looks, which are beautiful in an industrial sort of way but finished with a delicious paint job
    But looks ain’t what it’s about. It’s a special amplifier, and if you have thoughts on big Tannoy cabinets with current hungry drivers, then the STA100 should be on your radar.
    Top restoration job Will, you should be proud, Tom is!
    "lack of passion is fatal"


    Vinyl: Thorens TD-124mk2 / SME-312 Aluminium 'special' / SME M2-9R / STEREO: Etsuro Urushi Cobalt / Shure M3D / Ortofon SPU A95 / Cartridge Man Music Master / Shure - SC35C (US) / SAEC C3 MC MONO: Miyajima Zero B 0.7mil mono / Miyajima Premium 1.0 / Amps & SUTs: Radford STA25 mk3 / AD Audio 'Satchmo2' pre & LCR phono / Hashimoto HM-7 SUT / ETR-MONO SUT Digital: Audio Note 4.1 (with DAC5 upgrades) DAC / Roon / Tidal Speakers: Tannoy 12" MGs' in RFC custom 'Rutland' Cabinets with RFC crossovers / Tannoy ST-100 Super Tweeters Cables: LFD Grainless phono / RFC Mercury / Duelund DCA16GA tinned copper / Kimber 12TC / SW1X Audio Design USB-SPdif / Duelund DCA20GA interconnects / SW1X Audio SPDIF Aero 6 / Mains Power Conditioner / Box Furniture rack / Audiodesk Systeme Vinyl Cleaner / a very beautiful & understanding Wife!

  2. #82
    montesquieu Guest

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    Quote Originally Posted by WESTLOWER View Post
    Yes well said Edward. The synergy Tom has put together to get the most from the music he collects and loves is the key here. Every element is thoughtfully introduced and if it isn’t of the required standard it goes. The Radford STA100 is an endpoint for any system but for Tom’s brew it’s perfect. Perfect is a big word in this game and one should utter it with care, but in this system the word fits. I had my doubts I’d be able to really agree on the justification of extra power the STA100 delivers over the smaller stablemate, the STA25. I have the STA25 feeding Tannoy Monitor Gold 12” in RFC custom cabinets, and quite frankly it just works so well.

    The STA100 delivers music, as said by Edward, with ease and feels so effortless and in control, not that the STA25 doesn’t but this is just something else, something different which is hard to articulate. I said on the day it feels like one of those New big arsed Rolls Royce cars, classsy, big, luxurious with all that power to pull away, and plenty in reserve.
    I haven’t even touched on the looks, which are beautiful in an industrial sort of way but finished with a delicious paint job
    But looks ain’t what it’s about. It’s a special amplifier, and if you have thoughts on big Tannoy cabinets with current hungry drivers, then the STA100 should be on your radar.
    Top restoration job Will, you should be proud, Tom is!

    Thanks Adam, yes with the benefit of a bit of miles on the clock the grin on my face just gets bigger ... in so many ways it's the same amp that was send down for restoration, the sound is still as clean and powerful and 'right' as it was before. And yet the improvement is palpable, the atmospherics are something else, the bass just that bit more defined, the detail that bit more perceptible, all without losing that relaxed effortlessness and snappy agility when it comes to timing.

    Indeed - very happy.

  3. #83
    Join Date: Dec 2018

    Location: Danmark

    Posts: 5
    I'm Torben.

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    Hi.

    I realize this is an old thread, but I have a question:
    Is the restored STA100 still running the output valves in Ultra Linear mode at 600 Volts?

    Torben

  4. #84
    Join Date: Oct 2016

    Location: London

    Posts: 313
    I'm David.

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    The answer is yes. If you look at the TT100 restoration thread you will see that KR100s wouldn't work with the same anode / screen volts whilst Genalex and GE ones were perfectly happy. But why the question?

    Sent from my ONEPLUS A5000 using Tapatalk

  5. #85
    Join Date: Dec 2018

    Location: Danmark

    Posts: 5
    I'm Torben.

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    I am interested because I own an STA100. I got it from my teenage brother in 1982. It destroyed Gold Lions one after another until I set the current a lot lower and used GE6550A's instead. It has stayed in service with another family member for nearly 30 years but is now back with me. I was told, that it had started to distort (that is all I know so I will have to take a look at it). I would feel more comfortable with a somewhat lower B+. These valves are quite expensive.
    I will have a look at the TT100 thread. Thanks.

  6. #86
    montesquieu Guest

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    Quote Originally Posted by Herrmann View Post
    I am interested because I own an STA100. I got it from my teenage brother in 1982. It destroyed Gold Lions one after another until I set the current a lot lower and used GE6550A's instead. It has stayed in service with another family member for nearly 30 years but is now back with me. I was told, that it had started to distort (that is all I know so I will have to take a look at it). I would feel more comfortable with a somewhat lower B+. These valves are quite expensive.
    I will have a look at the TT100 thread. Thanks.
    Yes the STA100 was known for putting stress on KT88s especially modern ones. But I ran mine very happily unmodified with KT90s for several years before it went to Will for restoration - prior to that it had only had some fresh wiring in a couple of key places, a few electrolytics changed, and the big caps carefully reformed after some years of reuse. It ran fine at the full voltage. There are some tricks getting the splitters balanced though.

    Talk to Will at Radford revival he may be able to bring yours back to life he has just completed ground up restoration of five of these including mine and I’m sure would turn yours around quickly. It cost me £100 shipped from Finland on a pallet when I first got it so in the grand scheme shipping isn’t a barrier.

  7. #87
    Join Date: Oct 2016

    Location: London

    Posts: 313
    I'm David.

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    Hi Hermann
    Out of interest what did you lower the bias to? The standard setting of 2v or 60ma is not unusual for modern kt88s.My Leben runs KR88s at the same bias point and the Cannonball amps I build run them harder in Class A. When you change tubes on the Radford you should rebalance the output tubes with the internal pot for each channel. It's not that difficult if you've got an oscilloscope and dummy load, but if you're not teccy of course it's a bit complex and you need to take the bottom cover off, exposing high voltages.
    Cheers
    David

    Sent from my ONEPLUS A5000 using Tapatalk

  8. #88
    Join Date: Dec 2018

    Location: Danmark

    Posts: 5
    I'm Torben.

    Default

    Hi
    I lowered the current to 50 mA corresponding to a total dissipation of 30 W.

    I know the purpose of the balance pots, and I do have access to all the necessary equipment.
    When I get the time (may be a while) I will power it up carefully. I am not convinced there is anything wrong with it at all.

    Torben

  9. #89
    Join Date: Oct 2016

    Location: London

    Posts: 313
    I'm David.

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    I'm sure it's not the overall dissipation at 60ma that's the issue. I think it's the high screen voltage. If it was my amp I would do two things:
    1. Add the choke in as per the tt100 power supply which will lower HT slightly
    2. Add an additional heater supply for two of the output valves and run the higher rated (and to my ears sweeter sounding) KT120s (or even kt150s if they'll fit!)

    I've never tried kt90s but from the spec are higher rated and would do the job very well. The Radford design tends to minimise the impact of the tube sound anyway.

    Happy Christmas!
    David


    Sent from my ONEPLUS A5000 using Tapatalk
    Last edited by AD Audio; 25-12-2018 at 11:11.

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