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We have Lux. The manual not quite finished but we've built a few sets and can do custom builds now.
The linked page gives the pricing and description. Starts at 900USD for the base kit.
It's been playing and impressing in our system for a few weeks now. We built two, one with film caps and one with standard ecaps. Once run in, there is no contest. The film capped supply is better in every way.
The circuit is Thorsten's. We will call it: reactive interstage.
Regards
brian
Take control! DIY.
Follow Ups:
Earlier Thorsten said he wished (little confused as thought he had a major role in the design) for
-WE sockets
-10v heater windings
-310a/b for gainstage
-311a/b for interstag
-274 rectifiers
Also just below Gordon Rankin had his own suggestions.
Would any of these be an improvement and make more sense to the early current design?
Brian,
Someone familar with my work emailed about this.
I have been doing this for years on all my SET Guitar Amplifiers. Basically I call it reactor follower. The pick is of my 25W single 6550 guitar amp in use with the Bears.
It's not an interstage as you do not have a transformer.
A few things I would change in your circuit is the following:
1) The input impedance of dual 5687 is too low for EF86.
2) The swing of the choke is too low for the 300B.
What I would do is swap out the 5687 with a 12B4 and use a choke between 4k and 5k dcr so you get a swing of 2-3x what the 5687 can do. Also you can up the resistor into the 12B4 to 680k or more and it would be killer.
Thanks
Gordon
J. Gordon Rankin
.
Take control! DIY.
HI Brian:
The CJE film cap for B+ supply available for sale separately?? If yes, how much for each??
Hercules
Hercules:
I need to check on this.
Brian
Take control! DIY.
NT
A little easier to read.
Brian
Take control! DIY.
Folks,I am quite busy on other things, but I'll try "putting out the fire with gasoline" (David Bowie - Cat People).
For a long time I have been in two minds about Penthode drivers and High Mu, low output Impedance Triode drivers. I always liked both, but for different reasons and which was the "right" one dependend upon context, but invariably what one gained over the other in one area, it lost elsewhere. Brians summary is concise and good, it always was a choice of compromise, depending on many factors.
The topology used in the Lux, which was BTB originally dubbed "Bushido" by me (in both a transparent pun and as program - Brian suggested it was "counterpunnable") aims at bridging the gap.
The "reactive interstage" part between output stage and driver acts basically as "turbo charger", producing the more graceful overload and quicker, much easier overload behaviour of a gridchoke (or interstage transformer) loaded triode driver and then some, but without the interstage transformers often way too obvious bandwidth limitations and even better drive and overload recovery/overdrivability as triode & gridchoke.
Loading the cathode follower with a choke removes almost all of the objectionable sonic charateristics of a cathode followe (I hasten to add loading with a nice CCS does so too, but requires an extra negative supply of a good few volts AND chokes still sound a little more organic) and is nowadays easy to do, with a proliferation in available loading chokes (back when I did most of my work on SE Amp's the only choice was Tango TC-160-15 and importing these from Japan made some expensive interstages look like a good choice, gridchokes where also basically nada).
The actual voltage gain and thus the whole harmonic behaviour comes from the pentode driver stage, which Yamamoto San has championed for many years (even though only his most recent and somewhat cut down products achieved significant recognition, like the A-08 Amp driven by a WE 717), as well as Jean Hiraga and many others (I'll happily add my voice to this chorus).
So, bottom line, if you want the macrodynamic abilities and easy overdrive of the Triode & Interstage Transformer or Gridchoke drive combined with the finesse, delicacy and tonal colours of a 91 (or my earlier C3m/EL84 Legacy), have your cake AND eat it.
There will be cases where the Lux will be possibly even marginally worse than a LD91+, on detail retrieval and delicacy (only VERY MARGINALLY though), I would put these cases in the use of 103db/W/m or above efficient speakers (and we talk real not paper efficiency which cuts numbers right down and readily excludes most Lowthers, all Tannoys and Altec Coaxial and anything from Fostex's full range series) in normal sized rooms, where you rarely exceed the first watt.
So all of you with Avant Garde's, Beauhorn Virtuosos, Klipschorns or Oris Horns (et al) and LD91's can sleep well. The rest, well, if you never play Mahler, Ravel/Mussorsky, LedZed, Bela Fleck or Moloko and similar SPL intensive stuff, sleep well too, the rest I suggest may face sleepless nights. If the speaker is more like a real 95db/W/m (or lower) AND you like to handle things more complex than "Girl and Guitar" I would now recommend the Lux, basically cojones like the Castro Brothers, giving the one fingered victory salute to the worlds richest and most powerfull nation for almost five decades!
I hope that puts things into context and I actually would consider the Lux still "two stage" in terms of gain structure.
Now, how can I get Brian to make a version that has old WE Style socktes for both the input and interstage position AND 10V heater windings, so I can make one with a 310A Gainstage and a 311B Interstage (plus 274A rectifiers and real 300B's of course, me being a bit snobbish)?
Kind regards Thorsten
PS, for a lovely CD, try "Iz - Facing Future", not neccesarily audiophile and some tracks have some major mike overload, but boy has this guy a voice, awsome!
Hi,
What is your recommendation? Lux or LD91? I have a Marantz CD player (with valve output), a Django preamp and a Bastanis Prometheus II loudspeakers (~100dB).
I like “world music”, voices and instrumentals and jazz. So, no too much complex music (I sink!)
What is the differences (Lux and LD91)? Sonority? Power to drive the Prometheus? Ambiance? Image?
Thanks for opinion!
> Now, how can I get Brian to make a version that has old WE Style socktes for both the input and > interstage position AND 10V heater windings, so I can make one with a 310A Gainstage and a > 311B Interstage (plus 274A rectifiers and real 300B's of course, me being a bit snobbish)?
You mean something like this (Or the first stage in pentode mode)?
Raymond
Hi,
> You mean something like this (Or the first stage in pentode mode)?
No, not at all, I mean the exact circuit here:
Except a 310A/B instead of EF86 (and adjusted values where required) and a 311A/B instead of the 5687 and of course used as full pentode.
So, nothing like that, except for same tube numbers.... ;-)
Ciao T
Thorsten
I have genuine appreciation for you taking time out of your busy schedule to discuss the topic - your reference to different speakers and music is most instructive.
Keep well
Raymond
T
thanks for that.
Brian
Take control! DIY.
Hi Thorsten,
I'm interested in the kit, but I hope those 12 Watts have got "Cojones" more in the way the Christian martyrs faced the lions without abjuring their faith, Churchill defied Hitler or Mandela the Apartheid than in the way two murderous tyrants "show the one-fingered salute" to the USA using as weapon the suffering, hunger, humiliation of their people while they pile up millions in their well provided bank accounts in the Caiman Islands. There's no bravery in that, but Tyrany.
Regards,
Raul
Will the Lux take well to different output tubes ?
Suppose that 12W is too much (how do you get 12W from a 300B ?), and something low powered like a 2a3 or 45 is more appropriate (or maybe you just want to fiddle), will there need to be much to fiddle with, besides filament and B+ supplies?
Hi Michael
The power transformer has all the taps for 2A3/45 etc B+ and filament. The only thing is there would be some tweeking of voltages on the interstage section to adjust the bias on the grid of the power tube to maintain operating points. Also the WE connection caps would have to be adjusted to match the gain of the power.
12W: Most of the hi-eff speakers I know can handle > 20w. A little extra power just means more headroom. The 300B itself is run quite conservatively : anode to cathode is about 350v x 80ma = ~28w.
The 12w comes from the way the reactive interstage works. Usually when the 300B runs out of steam the wave form flattens and more input doesn't give much more. The Lux starts to flatten out much more gently and is pretty linear up to about 12.65watts. Subjectively it gives more dynamic headroom; it can be heard.
Regards
Brian
Take control! DIY.
Thanks for the info.
I guess the big question though, is this better than the ladyday WE91 ? Is there any reason why one would chose one over the other ?
... and that $900 entry point is REALLY tempting !!!
Hi Michael
We have done some limited head-to-head comparison between the 91 and Lux. I would characterize it this way: the 91 has its trademark ripe (not over-ripe) singing tone that it is known for. It's hard to beat on that count. Where the Lux excels is the way it 'hangs together' with no smearing or loss of coherence when the music gets loud and complex. That quality makes it sound much more powerful. Thorsten has also suggested we can up the operating points and get ~18w on musical peaks, so we may be able to get even more of that quality. Also the film caps in the power supply really give the Lux an edge in transparency.
Brian
Take control! DIY.
I have the luxury to AB compare the LD WE91 and the Lux in Brian's new office. My impression is the Lux definitely has more drive and punch. The WE91 may excel a little bit in the tone, but not much. Either way, both are excellent choices. Given that the Lux puts out 50% more power, it may be slightly better in driving more difficult loads.
Too bad because I am induling myself in the listening, I got a parking ticket. For those who are not aware like me, the road when Brian's new office is do have cops dishing out parking tickets, so beware.
I would like to try the Lux in my own listening environment.
Raymond
rtsang, I am sorry about your parking ticket.
Thanks a lot for sharing your impression of the Lux as compared to the LD '91. I would really appreciate if you could provide us with some more information about the rest of the system you listened to. I am especially interested in the speakers and the pre-amp.
Thanks and regards,
- josi
The source are Bix with LCR Cole or the Tentabs CD player.
Preamp is the new Django TVC (without remote).
Speakers are some clone of Tannoy built in China.
You have to ask Brian for the details.
I am really looking forward to listening the Lux at home.
Raymond.
Thanks for the information, Raymond. Do you know if Brian sells the Tannoy clones?
Good luck with testing the Lux in your home. Please, do not forget to post your impressions here! Is it correct that you have the Dragonfly speakers? If so, I am really eager to hear your results.
Thanks and regards,
- Joe
Raymond, Sorry to read about the parking ticket. I'll have to research where people park their cars in our area. As I ride my bicycle to work I don't pay attention to this.
We can arrange for you to try out a Lux soon as I get a couple built up units on the shelf.
BTW, we may be the only shop in Hong Kong that allows home trials of our finished kits.
Brian
Take control! DIY.
According to the 'disussion' of the benefits of the design, the newer amp's driver stage should be superior. From the site:> > > choice #1: pentode. offers necessary single stage gain but high output Z. tendency for highs/lows to be bandwidth limited. Clipping: not nice. Sound is delicate, immediate and pleasant 'bouquet of tone'. Fast! and retrieves the finest details as it sweeps the sonic landscape. Can swing the necessary voltage but but don't ask it to lift heavy objects. the DHT needs more muscle.
choice #2: triode. gain-challenged, needs more than one stage. (Hi gain versions sound like solid state). Low output impedance, wide bandwidth, great slam and dynamics. can be used with a grid choke for greater perceived power. Muscular, but lacks the refinement and delicacy of the best pentodes; leaves behind some of the fine details.
choice #3: re-active interstage. pentode on the input. paralleled sections of a triode with a choke loaded cathode. direct couple to the grid of the DHT.
the DHT gets what it likes: lots of swinging volts and iron fist control, even when driving the grid positve. This is Lux.the pentode does what it does best: gives tons of voltage gain driving the undemanding load of the re-active tube interstage. The interstage is loaded only with the following grid and cathode choke so bandwidth approaches DC to light and is sonically neutral, no cap coupling to the DHT. The DHT thinks the choke of the interstage is it's very own grid choke. And we still have our pentode! < < <
Seems Thorsten, after many years of arguing (in a technical sense) that single-stage drivers were the way to go, has perhaps changed his views. Or perhaps the discussion on the site refers to tubes that are readily available and of low cost to fit a price-point, rather than in the absolutes that it implies?
Anyhow, I can imagine the amp is a fine performer and will be suited to many a music-lover's tastes and systems - and is available at what seems a nice price.
Cheers
RaymondEdit: Minor changes to improve intelligibility.
Hi Raymond
Thanks for commenting. Thorsten has, surprisingly, answered for himself.
For me, I don't think there are absolutes, just different solutions, each with their own set of efficiencies.
I guess a single tube spud amp would be the ultimate in direct sound but very limited otherwise. Next would be a single high gain triode or pentode to drive the power tube, with all the oft-discussed challenges to implement each with its own tradeoff. Most common is the dual triode 6SN7/6SL7 etc which is really two stages in one bottle and these can sound very good as well but it's a balancing act of gain vs drive. The Lux parallels the two halves of the 5687 in the gain-neural interstage so it acts like one tube, and with a little circuit trickery, dispenses with the coupling cap that would normally be on the grid of the 300b, as well the choke adds the turbocharging effect Thorsten describes. Subjectively the package is very transparent and direct sounding.
My descriptions were just an attempt to put into words what i hear subjectively together with Thorsten's explanation of what happens in the circuit.
The beauty AND the beast.
Regards
Brian
Take control! DIY.
Brian, what EF86 tubes will you supply? I presume not Mullard NOS. Thanks.
Dean
Yes you presume correctly.
We will supply the Russian 6*32. They are quite OK. I've got various Mullard, Siemens, Amperex, solid gray, shiny solid and mesh of many types. They all sound good but different and can be used to tune the sound to the romantic or aggressive, depending on taste.
Brian
Take control! DIY.
You guys even got a choke to fit in the power supply final version! This really does appear to be "beauty and the beast".I can't wait to get mine.
Seems to be great stuff, but why the capacitor peep -show?
It makes me nervous to look at, I would prefer a closed cabinet for the caps.
Any pics from the inside?
Cheers,
Juergen
Hi Juergen
A full cover would mean mounting from below. We may cover the caps with black shrink.
You are thinking of safety?
There are no voltages at the top side.
Regards
brian
Take control! DIY.
Hi Brian,
no, its just the look.
I imagine one big cover for the caps and the chokes beside.
But black caps would be better already.
And thanks for your work again, it looks like a light in the dark world of high end madness. Good components, good circuit, nice cabinets ( mostly ))) and, almost unbelievable, even I can afford them!
Very tempting, although I'm happy with my LD....
Ciao,
Juergen
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