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The Elekit TU 8500 Valve Preamp - A Knockout In Value and Sound Quality!


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*** AN UPDATE to the performance of the phono stage is written by me several postings below here: ie, further on in this particular post, not in a separate one. 

 

Hi all, I just wanted to share my latest project, something I've been saving for and wanting to build for some 18 months. It's an Elekit TU 8500 valve preamp, direct from Japan, complete with all assembly instructions in Japanese! Fortunately, the instruction sheets are so beautifully put together from beginning to end, as well as the fact that I've been building kits on and off for decades, that I had no issues with the build as such. It did mean I had to double check some items for orientation, but that was no big challenge at all, really just precautionary. It's certainly not a kit I would recommend to beginners, but if you have good soldering skills and can at least follow picture directions, then you should have little problem with this one. 

 The sheer quality of the boards and casework is truly admirable, as everything aligned to perfection and once I fired it up and checked the 140V and 12V+- test points all was well. This preamp is SILENT(!), thanks to a classy R-Core transformer often found in much more high end gear and a comprehensive DC power supply. Even the phono stage needs full volume through headphones to hear even the slightest of noise at a very very low level, the line stage is for all intents and purposes completely silent.

** This TU 8500 preamp is far quieter than a $3700NZ TRI KT88SE Integrated amplifier that I owned and loved for five years! 

 

Board layout is exemplary and I had a great time being a bit OCD in aligning all my components in straight lines and resistor values facing the same direction .. unless they were mirrored :)  I even went to the extent of filing down the board joins, as they all come connected together and require breaking off, sort of like breaking tiles, not as nerve-wracking as you might think, as they snap off easily. The solder flowed effortlessly with every joint and I double checked each one to make sure it was shiny and perfect. 

 Some weeks before receiving the kit in the mail, I had bought up both the upgrade op-amps for the phono stage and from Parts Connexion, the upgrade Amtrans resistor kit and two Mundorf Evo capacitors, supposedly for the phono stage coupling to the line stage .... until after ordering them, found out that I also needed two more for the line stage itself, DOH! I umm'd and ahh'd a bit, before remembering that I had some high grade polypropylene caps (630V) that I had bought for a Trevor Lees preamp some years back, so I used two of these in the phono stage and the Mundorf Evo's in the line stage. You can see them easily in the pictures below. I also replaced the stock 0.1uF caps in the phono stage with two Black Gate 0.1uF NP caps, something I've done with other amps to very good effect, these tiny capacitors are super clean and transparent and are brilliant as power supply bypass caps in the right circuits, as Martin Collums discovered to his great delight when reviewing a series of these brilliant high quality capacitors several years ago. The kit also comes with quite a number of quality low ESR capacitors for use outside of the power supply. Great stuff. 

 The TU 8500 lit up from first switch-on and has functioned perfectly ever since, a week later. I've already put some 30-40 hours on it and the bass has most certainly filled out in the last 10 hours or so, taut, dynamic and organically alive. I'm also very impressed with the phono stage, very clean, quiet and detailed, with excellent dynamics as well, although the Black Gate caps will take quite some further time to run in, as usual, as well as the big polypropylene caps. The upgrade op-amps also seem excellent, OPA2227P x 2. 

 Initially, I used the stock supplied Chinese 12AU7s and had an absolute ball listening through headphones to hours of an iTunes downloads folder! So much fun and even though the preamp was brand new and there was some extra warmth from the stock 12AU7s, I could imagine that many folks would be happy just to leave them in there and listen to music, particularly with Mp3's and AAC tracks. 

Still, I was keen to hear how my top grade Psvane 12AU7-T's sounded in here, so the next day in they went. Yes, well, this is why we pay extra for top class bottles! Transparency and speed, extension top and bottom, openness and 3D space. Highly recommended! The Ziggy Stardust and the Spiders From Mars Live soundtrack album has never sounded this good! 

 I did pop in a couple of Mullard valves that I thought were of the right species (the preamp can accomodate both 12AU7 types and the lower MU 12AT7s), but it turns out I had mislabelled the ECC88s as 12AT7s ... they are not! No wonder they glowed very brightly (see pics below)! They were a bit soft and warm anyway and once I'd realised my mistake, I replaced them with the Psvanes and all was well, no harm done. 12V into a 6V heater may not have gone so well.  Last task is to find a cable tie that will stick to the base for the main's cables from the transformer. 

 I bought my TU 8500 from an eBay site, it shipped on Dec 22nd, suggesting it could be late Jan/early Feb before it arrived and instead it sped here in four days (after clearing their store) and took another five or six days to get to my PO, including redirection (we'd moved house). No issues over freight speed! The Parts Connexion also posted free of charge for the resistor kit and caps, well done them, about 10 days arrival time. 

 If you'd prefer to buy in Australia, there is a Gumtree site that will post from WA for $65, bringing the price to around $740AU, minus the upgraded parts which they don't keep in stock; Hammersley, Sterling Area. That would take you up to around the $800/820 mark including the upgrades. 

 The eBay site I bought from was here and included a voucher code for some $40AU off the list price: japanmegamall (4167)

 All in all, a very highly recommended 'kit' that performs way above it's station and price range. I am extremely happy with my TU 8500 and would now really love to build the TU 8200 headphone/speaker amp this year, with it's upgraded parts. 

 

Sorry about the bluish/green light in some of the pics.

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Edited by Lightstream
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3 minutes ago, Rhythm Willie said:

How much was the kit?

 

Initial purchase including GST (yes, the buggers got me!), a 5% discount voucher and shipping, $680AU. Add another $36US for the resistor kit plus Mundorf caps and I'm not sure what the op-amps were, all up around $750/760AU. It's regularly rated in reviews as being right up there with $1500-$2000US preamps, possibly even a little better with the upgrades. 

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I am deeply impressed with it! Well worth the time to put it together. It also has a Zero Gain bypass switch on the back panel, but most folks find it sounds preferable with gain switched in. 

 I run a Questyle QP1R DAP via optical out into a Schiit Audio Multibit (Mimby) DAC and the superb Slinkylinks pure silver ICs into the preamp. Even my spare Technics SL-BD20 turntable with a brand new LP Gear stylus sounds terrific into the phono stage. The Direct Drive SL1900 and EEI 500 Parabolic (again with a new LP Gear replacement stylus) hasn't had playtime with it yet. 

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I'm actually rather astonished at the sheer openness and size of the soundstage, maybe the stock preamp is not quite as expansive as mine currently is. Depth perception may not be as cavernous as the very best, yet the size of the stage on say, Bowie's Live Ziggy & TSFMars double album is really quite something, the Sennheiser HD540 Reference headphones (Mogami cable and pleather pads) and the bones of my head doing a big vanishing act, even more so than usual with the Mimby/Magni 3 combo. The latter has a purer high treble and is drier overall, though is incredibly quiet and dark in the ambient spaces, allowing the tiniest of sounds to appear with great precision. The TU 8500, linked with White Zombie's La Cacanya pure silver ICS to a very highly upgraded headphone amp from Silicon Chip (dual OPA627BP op-amps - or audioGD HDAM, Black Gate and  Nichicon Muse caps/Dale resistors with an audioGD class A power supply) has a huge soundstage and full, taut and organically detailed bass that is quite addictive, the drum kit on the Ziggy album is fantastic, complete with it's own ambient space on the stage that varies quite noticeably between tracks, recorded on different nights, I believe. Dynamics are naturally fast and with a 3D density to them, the latter also being a fine feature of the HD540s, giving them a natural organic aliveness that seems to evade many of the much newer cans I either own or have heard over the years. Still a true reference in so many ways and while not being as hyper-detailed as so many of the newer so-called High End cans are, they have a balance that is almost second to none overall, as I have them here. The slightest change in dynamics, clarity, soundstage and vocal alacrity will immediately available, it's why they are still my most musical goto headphones over the last 30 years now :) They tell me that somewhere in the chain, I can get even better pure and extended treble. Not even the HE400S (Focus A pads) can hold a candle to the sheer openness of the HD540 Ref1s. I won't even go there with some of the other modern designs I've heard. 

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Lovely work on your part. Those kits sound amazing and sound way above their price point, easily rubbing shoulders with preamps that cost 5x as much. How hot do the 12AT7s get? They're pretty close to your Mundorf caps there. Most preamp tubes run at about 70-80 degrees and those caps are rated to 85 only. Do you have an IR thermometer? If not, I highly recommend getting one as a valve user! They only cost $20 from ebay.

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19 minutes ago, Ittaku said:

Lovely work on your part. Those kits sound amazing and sound way above their price point, easily rubbing shoulders with preamps that cost 5x as much. How hot do the 12AT7s get? They're pretty close to your Mundorf caps there. Most preamp tubes run at about 70-80 degrees and those caps are rated to 85 only. Do you have an IR thermometer? If not, I highly recommend getting one as a valve user! They only cost $20 from ebay.

Thank you for your kind words on my preamp creation, I had a ball putting it together and took my time making sure everything was spot on. Around 7 - 7 1/2 hours all up. Upon going over the circuit in a final pre-switch on check, I discovered that one of the Amtrans resistors was the wrong value, 120k ohms instead of 100k and although it probably wouldn't have made a lot of difference in the power supply, I decided to put the correct value in anyway, so I had to disassemble the preamp again to do the re-soldering. 

The Psvane 12AU7s don't run that hot, the Mullards ECC88s I accidentally put in there for a day or so ... wowza! The case only gets mildly warm over quite some hours. The Psvanes have probably quite a few hours on them now, I'd imagine half their lifespan, I bought them in late 2012 and they had a lot of regular use for three years. It would be interesting to try a new set and maybe a pair of 12AT7s as well, maybe even RCA Cleartops, I hear they're rather fine in this preamp. 

 Good to hear about the IR device, especially as I'd like to get another valve power amp again, preferably that Elekit TU 8200 with headphone jack! 

Edited by Lightstream
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AN UPDATE: 

 I have had some time this afternoon to plug in the Technics SL1900 Direct Drive t/t into the MM input of the phono stage, initially with the EEI 500 cartridge with a new LP Gear stylus, who's basic sound sig is a punchy, dynamically weighty and well focused sound that has a slightly rolled top end that ultimately lacks really fine detail. It's a fun and very playful cart nevertheless. Since I have three different cartridges all lined up on their own headshells ready to go, I used three live albums and Supertramp's 1985 Brother Where You Bound studio recording. 

Live albums are: my original 1972 copy of Neil Diamond's Hot August Night; Fleetwood Mac-Live, specifically the very telling track by Lindsay Buckingham, Never Going Back Again; Genesis' Seconds Out, Firth Of Fifth and the aforementioned Brother Where You Bound. Live albums not only bring me into the audience if they're well reproduced, but also the sense of sheer space on stage and from the audience. They can often have a huge range of dynamic colours and shapes. 

 The other two cartridges were the Ortofon OM20E (new stylus with maybe 10 hours on it) and a Stanton 681EEE that has seen some hours. 

 All of them are quite different and the TU 8500's phono stage very easily gave an all access pass to the variations in performance. The EEI 500 is as described above, tracks well, handled the high strings without screech as the Prologue at the beginning of Hot August Night builds, then kicks butt on the weight of drums on the intro to Crunchy Granola. Good fun, but the very telling spoken intro and following audience backchat before Solitary Man are not as clearly available as I know they can be (an older Supex SD1000 MC cart on a previously owned Technics SL1210 MkII was far superior). The same tracks with the OM20E was, well, Ortofon pristine in it's clarity, effortlessly tracking the strings, crystal clear vocals and the audience backchat, yet lacking in the dynamic clout of the drums and guitars. It was like listening to a very clean and well ordered copy of a performance that was a bit sat-upon and lacking any real involvement. Superb tracking though. 

 Lastly, was the Stanton 681EEE. The bass was back, immediately heard in the audience ambient space and around the stage, a weight of the air, almost. I was almost amazed at the way it sailed through the rising in level of the bright string section, still easy to hear the tone of the strings and the body of the basses. The the drums come into play and the attack and weight of them was exciting! NOW I am at a real live concert! I'm feeling like I'm actually participating, the strings, guitars, bass and Neil's voice all have energy and life, everything has life! The 681EEE has the dynamic weight of the EEI 500 and the (almost, it's much more 'used') easy clarity of the OM20E's top end, but adds so much more in the sheer organic life to the performers, dynamic accents and scales. I was quite astonished to hear such a performance lift. So, onto the Buckingham track, the easy speed and metallic detail in the guitar strings were pure delight, Lindsay's voice full of expression and the puffs of air as he loudly whispers, "I'm never going back again ... " are so tangible. 

  The Supertramp, BWYB album is dynamic and clean. No problems here either and I enjoyed it so much I ended up listening to the whole side until other chores called me away. What a surprise .. again ... this cart has kinda shocked me before some years back with the fabulous Deep Purple Live in Japan album on the SL1210 MkII, but it's been packed away since then. It really has quite a wonderful dynamic alacrity that allows for truly natural and effortless performances to get lost in, a way of lifelike expression that just draws me right in, even more so than the EEI 500, my previous favourite. It deserves a new stylus and I'm considering a fine JICO, although since height adjustment on the SL1900's arm isn't available, I may not be able to get the very best out of the fine Shibata diamond. LP Gear have an excellent replacement, regardless. 

 Have I gone a bit overboard with this little review? Maybe, but it really shows me how good this phono stage on the TU 8500 truly is and it's been well worth the 18 month wait to at last have it in my home. For now, the Stanton 681EEE rules the roost for sheer musicality. 

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  • 1 year later...

I have also built one of these pre amps, however the only extra parts I have are a couple of  JJ ECC82 valves, which I still have to fit at some point.

This was my first DIY valve pre, very easy to build with the supplied instruction manual.

As has been pointed out above it is a very good piece of gear, I use it to power my DIY Nelson Pass First Watt M2X.

This combination has replaced the Copland CSA29 in my main system, I like it that much!

 

If anyone was looking at a complete kit for a pre of any breed (Valve or SS) I would seriously suggest this one.

 

The only downside I can think of is that the label for the front panel controls are on the lid. But are pretty self evident.

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@Lightstream, i have the Elekit TU-8200R tube amp, built by Chamila of RF Waves in WA, my first tube amp and couldn't be happier, i do not have the skills to complete this sort of project. There are  few WA SNA members who have extolled the tech virtues of Chamila, so i have no doubt of the build quality of my amp. Sold my keeper amp, Exposure 2010, after a couple of weeks of listening to the Elekit, outstanding value for sound/money. Chamila put the labels for the controls under the controls. There have been very few days that it doesnt get listened to. My second system with a Quasimodo gets minimal use at present as well, you will not be disappointed with the 8200

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1 hour ago, wen said:

@Lightstream, i have the Elekit TU-8200R tube amp, built by Chamila of RF Waves in WA, my first tube amp and couldn't be happier, i do not have the skills to complete this sort of project. There are  few WA SNA members who have extolled the tech virtues of Chamila, so i have no doubt of the build quality of my amp. Sold my keeper amp, Exposure 2010, after a couple of weeks of listening to the Elekit, outstanding value for sound/money. Chamila put the labels for the controls under the controls. There have been very few days that it doesnt get listened to. My second system with a Quasimodo gets minimal use at present as well, you will not be disappointed with the 8200

I would love to build my own TU-8200 some time this year. I am listening to the TU-8500 right at this minute, running into my homebuilt version of the old DIGI 125 amp and extremely efficient 1968 Sansui SP300 speakers (around 104dB, quoted), sounds magnificent! If your TU-8200 runs anything like as efficiently, quiet and reliably as the pre-amp, then you have years of joy ahead of you. I do run Psvane's top of the line 12AU7-T valves and they too have run magnificently for years, though I am considering a new set some time soon, considering they also saw fine service for a few years in a TRI TRV-88SE integrated amp. My absolute favourite valves in this pre-amp, utterly transparent from top to bottom, neutral and silent. 

 I can recommend the various resistor and cap upgrades if you so desire at a later stage. It's terrific that you are getting so much joy from your amp, do you use head[phones with it too? One reviewer was ecstatic running h/phones from that amp. 

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@Lightstream, i have Monitor Audio RS6 speakers, 91db/w/m, 6ohm. Recently had a fellow SNAer over who believed 8wpc was only good enough for headphones, played No-Man, Love you to bits, seeing his jaw drop more than once at the volume and impact of sound was priceless. With your 104db speakers, the neighbours need to be prepared for thunder

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My speakers are 92dB/w/m 8ohm. Admittedly I use a 25w/ch power amp. M2X. but yes I have driven them with the Pass ACA at 8W/ch and it is gooooood.

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? Actually, the horn speakers are so efficient, yet do so with such ease and communication without strain that the room is filled with music without edge or the pushy mids that are typical of so many horns. I am still stunned every time at how the drivers load the very air in a way that is totally unlike drivers that direct sound at you. The SP300's are keepers even if I had to move into a caravan! The Elekit pre-amp barely gets over 7-8 o'clock on the dial, 9 with the turntable input. 

Many folks don't understand that most amplifiers are only working on a few watts with reasonably efficient speakers. I recently restored a Japanese 2W Peak amplifier from the mid 60's that easily drove the SP300s and Onkyo Radians at around 90-92dB true efficiency and did it with grace and superb transparency. 

 Thunder with the SP300's is easy :) Though never sloppy! Those 12" bass drivers have 8 big Alnico magnets each and terrific electrical dampening, they actually take a good half and hour to really loosen up and become truly lucid, but when they do, oooh the organic, taut fluidity, very natural. Fast too. The cabinets also play little part in the proceedings, they weigh 36kg each. Even the mid horns have eight Alnico magnets each and the waist of each one is U-bolted to a solid cross brace. I'll just bet your system sounds wonderful!

 

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16 minutes ago, Batty said:

My speakers are 92dB/w/m 8ohm. Admittedly I use a 25w/ch power amp. M2X. but yes I have driven them with the Pass ACA at 8W/ch and it is gooooood.

I reckon real efficiency is underrated, there are so many really good low wattage amps out there and fortunately there is a bit of a resurgence of efficient speakers, to have music play with utterly no stress at good volume with only a few well designed watts can be a revelation to the ears. I admit to not having heard a good low wattage Pass Labs amp ...  although I have made a Zen pre-amp that needs more work. 

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If you are ever down this way, pop in, the ACA is good, runs off a SMPS too.

Pure class A, gets to about 60 degrees C :) that is hotter than the 25 watter.

I was surprised by it, had no probs with a pair of KEF Ref 104aB either, I must admit I have not tried it with the Usher S-520s. They are in the shed being driven by a MF A1.

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Thanks for the generous offer, Batty, I lived in SA for 7 years after leaving NZ in 91, I knew I was home before I even stepped off the plane, have loved the place like 'Country' since that time. Always look forward to going back there. 

 

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Thank you, much appreciated! I'd love to drop in on a fellow hifi/music buff and have a listen and a chat. Shared passion for a great 'hobby'. 

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On 10/04/2020 at 11:34 PM, Batty said:

Our music tastes may be different though.

Of course, all part of the fun exploring new musical adventures. 

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  • 4 months later...

Anyone have any idea on the output impedence on the elekit 8500? Unable to find anything online. I have had a couple misses with tube pres to match with the Yamaha B2 which has an input of just 25k ohms. thanks!

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6 hours ago, thejt said:

Anyone have any idea on the output impedence on the elekit 8500? Unable to find anything online. I have had a couple misses with tube pres to match with the Yamaha B2 which has an input of just 25k ohms. thanks!

Unfortunately not even the official website has specs for it, even in the Japanese version.

https://www.elekit.co.jp/product/TU-8500

It's a fair bet that an affordable valve preamp will have relatively high output impedance. My guess would be in the 1-2kOhm range.

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On 28/08/2020 at 12:37 AM, thejt said:

Anyone have any idea on the output impedence on the elekit 8500? Unable to find anything online. I have had a couple misses with tube pres to match with the Yamaha B2 which has an input of just 25k ohms. thanks!

I would try contacting this person :

https://tubesoundaudio.com.au/pages/contact-us

 

very nice and knowledge lad.

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  • 5 months later...

Don‘t know who told you the T7 was a low mu version of the U7, but it actually has about 3 x the gain. It is a totally different animal, a lot more like a 5965, and not a direct sub for a U7. Due to this characteristic, T7’s were more often assigned to phono duties while U7’s looked after the line.

 

I saw another review of this pre where a guy subbed in a T7 simply stating it was a lower noise version of a U7. This is utter nonsense. Moreover, it is highly unlikely that this tube’s bias points would have been optimised after simply plugging it in. Output impedance would also have increased (which may or may not be significant). Both these issues lead me to seriously question his credibility as a reviewer. All 12A variants would work in that socket, but.......

.

Personally, i would stick to U7’s from a reputable source. Your Psvane's sound like a really good option.

Hope this helps.

Edited by mach1
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Hi thejt,

I have a very strong suspicion there is a low impedance mosfet follower output stage on the right hand board (the signal would go through just this when gain = zero), otherwise you are looking at an unbuffered 7K anode follower output impedance, which I don’t think is possible (ie it’s a hybrid linestage). This would drive just about any amp with contemptuous ease.

Edited by mach1
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On 19/02/2021 at 11:51 PM, mach1 said:

Hi thejt,

I have a very strong suspicion there is a low impedance mosfet follower output stage on the right hand board (the signal would go through just this when gain = zero), otherwise you are looking at an unbuffered 7K anode follower output impedance, which I don’t think is possible (ie it’s a hybrid linestage). This would drive just about any amp with contemptuous ease.

As far as I'm aware, there is no MOSFET buffering at all, the RH board at the front is all power supply and the phono stage at the rear. I have no problem powering any amp in my stable, loads of output ... but looking over my pics again, I see no FETs anywhere .... unless I am very much mistaken. Main power amp in the system is a modded DIGI 125 amp, with all POOGE-style mods Litz wiring for the PS throughout. Runs beautifully. Great transparency and speed. Alive. I will be sticking with the Psvane 12AU7-T2's when I place the valves,  just so transparent from top to bottom. I may consider a set of matched RCA Black Plates as an option, I hear they are rather good, but have no idea if they have the overall transparency of the Psvanes. 

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  • 1 month later...
Posted (edited)
On 19/02/2021 at 11:51 PM, mach1 said:

Hi thejt,

I have a very strong suspicion there is a low impedance mosfet follower output stage on the right hand board (the signal would go through just this when gain = zero), otherwise you are looking at an unbuffered 7K anode follower output impedance, which I don’t think is possible (ie it’s a hybrid linestage). This would drive just about any amp with contemptuous ease.

Here is the circuit diagram, the only FET is in the power supply as a ripple filter, no other buffering. This pre-amp still runs as quiet as the day I put it together, the Psvane 12AU7-Ts as well; they've had several years of use now, 2 1/4 yrs in this pre-amp and another 3 or so in my TRI TRV-88SE integrated amp. It hasn't been a constant thrashing, as such, but no doubt a good couple of thousand hours + all up. 

 I may consider upgrading a few parts yet, possibly the power supply caps for Nichicon KG Gold Tune versions, or similar (they have been stunning in my restored 1977 Perreaux SP100 pre-amp, dropping the noise floor to so low it's not worth even listening for it at full volume and allowing for a new level of bass depth and impact, as well as a more 3D sound stage and dimensional vocals with a new silence around them).

In the Elekit TU8500, I have Mundorf polypropylene caps in the Line stage and  good quality polyester caps from from output of the phono stage, so I may move the line stage caps to the phono output and replace them with higher level Mundorfs. Just a thought at this stage. As a pre-amp to the hotrodded Silicon Chip headphone amp - with other mods in-between - the results are superb with the venerable Sennheiser HD540 Reference 600 ohm headphones, which have their own upgrades in Mogami cable and pleather pads. 

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Edited by Lightstream
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From the diagram, the FET is used as a constant current source for regulation on that supply line for 140V 

 

Like the way it uses OP amps for MC/MM 

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