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statman

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statman last won the day on October 2 2014

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  1. No they are not substitutes at all, completely different tubes.
  2. I'm always wary of the fine line between posting and self advertising , so I tend to let my blog do the talking, but as I've been invited........ Yes almost all of the work is sold in the US . I have US dollar prices on my web site as the higher AUD can be confusing to them. I always like to instigate an email conversation with potential customers, in order to establish a clear idea of exactly want they want in a product, and if you twist my arm....... In regard to feedback , the amp has no feedback at all, neither global or local. Not that's there anything wrong with feedback- in the right format and amount it can be very useful. As pointed out it helps with damping factor and provides better linearity with difficult speakers. In previous power amps I provided adjustable feedback , from zero to quite a good amount of damping, and even positive feedback for very low output impedance. And feedback is very useful for minimising hum and noise with less than ideal power supplies and earthing. And as also pointed out, too much feedback can be very harmful to the phasing effects- imaging, soundstaging, etc. There is something quite pleasant and enjoyable about a zero feedback power amp , AudioNote UK made a big deal out of it in their early days . Of course you need a relatively easy speaker load to get a flat monitor like frequency response, but in real life there's no such thing as perfect response, in fact the more "flat" the response , the more uninteresting the sound can become, I think we all tend to like a bit of coloration , to our taste. I tried this no feedback amp with quite a range of conventional and non conventional speakers and I found it enjoyable with all of them. Of course i didn't even attempt it with my "difficult" speakers - some speakers just need lots of power ( and the compromises that can come with that) With this no feedback amp, having a quad of power tubes helps , along with a good output transformer to give a reasonable damping factor that will drive most speakers . There might be a bit of coloration , but the openness and vividness of the amp would appeal to those looking for a bit of tube euphonics. The driver stage is very strong and contributes to a very clean output right up to and beyond its power rating. A lot of high power tube amps these days can be very tiring when they get close to their rated power , and rely on feedback to minimise noise and strident clipping. So I decided to leave the feedback out. If someone asked for a "stronger" amp I would probably put a bit of local feedback in it, with maybe a higher power output. Sound quality is all important, but I do like to build gear that is going to last , is well engineered and devoid of gimmicks and useless gadgets. A lot of power amps these days have inbuilt obsolescence with so much gadgetry , complex bias arrangements, digital readouts and protection circuits - something will eventually fail. I have 4 sets of Trimax monobloc tube power amps. Built in Melbourne in 1956 - a bit ugly but beautifully engineered - good design, very well built transformers . I replaced a few caps in them, but they are basically unchanged from the day they were built , and still sound very good. Tube design has come on from then, but the durability and engineering is an inspiration to me and I build the Suprateks to be used in 50 years time - although the audio world might be a lot more different than it was 50 years ago. Probably have emotional inducing full surround AI controlled music in our heads with not a piece of equipment to be seen.
  3. Pretty much the same at 20Hz as 1000hz. I put quite a lot of explanation into the reading of specs in the article, but its easy enough to build a preamp with extraordinary specs that sounds quite horrible. Phase coherence is the big one when it comes to determining the difference between a great and middling preamp, but thats for another day.
  4. I've done a very extensive and detailed guide to previewing tube preamps. Its on my blog www.supratekaudio.blogspot.com.au If moderators wont allow the link I'll paste it here as text.
  5. No i didnt. Call me tomorrow xxxxxx or email xxxxxxxxxx
  6. Item: Acoustat 2+2 Electrostatic speakers + 2 Carver Sunfire Amplifiers. Location: Margaret River WA Price: $5000 Item Condition: Very Good Reason for selling: need room. Payment Method: Pickup - Cash, Paypal, COD Only Extra Info: I never thought I would ever sell my 2+2's , but the time has come to finish off my listening room, and these big boys have to go. The 2+2 are quite well known on Stereonet, do a search on them and you will find how highly regarded they are. Personally , I think they are the finest electrostatic speakers ever made , and are still unrivalled . Whilst every other stat I've heard has a "stat" sound the 2+2 are incredibly natural sounding. Nothing else comes close to the sound of voice and piano like the 2+2. Trumpets and other horn instruments are so lifelike . Nearly 8 foot tall and a true line source , they sound the same at any vertical position. They have a soundstage that is scarily wide and deep and very realistic. The Acoustat are renowned for durability and very long life- the panels are bombproof and virtually indestructible. 20+ years and still SOTA for electrostatic design. I imported these from the US about 5 years ago- they have rebuilt/restored crossovers and HT bias and have split crossover/transformer so can be bi-amped . Like all stats they thrive on big power and an amp that is load tolerant . I found the Bob Carver Sunfire amps to be perfect for them- they can manage close to 1000 watts into 1 ohm , but at the same time sound as sweet and wholesome as a good tube amp. Do a search on Reg on Audio for a review that considers the Sunfire as good as you can get. http://www.regonaudio.com/Sunfire.html I consider the Acoustat/Sunfire combination a necessity to get the finest sound, so I'm including the two Sunfire amps in the sale. You could spend a vast amount of money on speakers and amps and not get close to the sound of the 2+2's. You'll need a big room with nearly 8 foot ceilings , or a man cave . I had a music professor come and listen to these one day, that extended well into the night. He couldn't believe how detailed, yet still so very musical they are. Will deliver to Perth , anywhere else pack and send, wont be cheap, but buyer will have the finest electrostatic sound you can buy at any price. I cant believe I'm selling them, but my horn system takes up a lot more room, and I need the space. Also have spare interfaces. Pictures:
  7. I put this article in my blog , but think it will be interesting to some here. A great Australian design that perhaps doesn't have the recognition that it deserves. " Over the years I've had a few of Martin Seddon's Azura horns. They are tremendously impressive - there's nothing else like a horn for dynamics and "you are there" sound quality. But I've never been able to live with them for long term. I need speakers that are accurate, and whilst its possible to use all sorts of implementation to get anything accurate these days, it isn't always agreeable. Horns do have a "horn" sound - some call it a "honk" or "quack", but its just a slight tinge to the midrange that cuts a little naturalness from the response. Or at least that is the impression I've always had. My Supravox 215 field coils in a large OB (see previous blogs) are the most natural and musical speakers I have , amongst my 4 systems set up in my (big) listening room. All the previous horn systems I've had used bass reflex, Onkens or sealed enclosures for the bass frequencies. I've never had a full horn system where the bass is also produced by a horn. The reason for this is that bass horns that can go down to the necessary 40 or 50Hz are BIG - they need a lot of floor space and dedication to own. However I've always wondered if a horn system really needed to be a complete horn package , where bass, mid and treble are all covered by dedicated horns, and the resultant synergy produces a sound without compromise and weakness's. Listening to Martins all horn system piqued my interest and for too many years now I've had a set of his 160Hz Azuras , with the intent to build his matching 50Hz bass horn. Martin uses the Line Magnetic LM555 field coil compression driver in his 160Hz horn. Its not cheap at $US5000 a pair. Its a direct copy of the very famous and desirable Western Electric 555. The Atlas PV5-HD costs about a tenth of the price and is reported to have been based on the WE 555, with some compromises, a phenolic diaphragm, alnico magnet etc. Martin suggested that it could be quite good in the 160 so I ordered a pair and we did some measurements that were very encouraging. But this time I definitely wanted a full range horn system, and the picture you see here is the result of a very intense week of woodworking. The bass horn is time consuming to cut out, and surprisingly quick to assemble. Its a L shaped horn, which gives the horn length in a reasonably compact shape (and appealing to a Ducati L-twin owner!) Cut off is 50 hz, and simulation looked very good. The driver is a Supravox 285 RTF , courtesy of my friend BobM , and ideal for this situation. At this stage there is no enclosure behind bass driver, but building that soon. It can be used with or without enclosure. With Enclosure Without Enclosure The 160Hz horn is mounted above the bass with wooden supports , and the treble tweeter is between the two. The tweeter is a Yamaha horn with JA4281 compression driver- fairly common but it does the job. The crossovers are something I just cobbled together out of my junk box to get it going - simple 6dB slopes with an inductor on bass, and caps on mid and treble for crossover points at 300Hz and 2KHz. Martin has a lot of experience with some sophisticated lower order crossovers (?) and I'll be investigating these soon. Seperate amps for all horns, so 6 tube amps, all with level controls for very fine adjustment of tone. Its consuming, but active/passive gets the results I require. So how does it sound? Well if you've only heard horns with non-horn bass , you haven't heard a horn system!! The most obvious thing is the very low levels of distortion, bass is very clean and defined , quite different from conventional moving coil drivers and just so involving to listen to. As is the midrange , that "honk" is virtually gone, and I think further work with crossovers/amps/adjustment will eliminate it completely. I get tired of trying to describe sound , so I'm just going to say its as good as I've heard. It takes a little re-conditioning of the mind , as there is so much that is so different , that you wonder if it is "too good" , but it soon becomes obvious that this is what it actually does sound like. Then I just put record on after record, as if hearing them for the first time, and its only early days for this system! I'ts a shame most won't get to hear something like this, let alone have the space (and dedication to fine music) to actually build it. http://www.azurahorn.com/index.html
  8. Ooops I meant JRiver, dont use computer much these days. I'll leave it at Steve's next time I'm up there. Yes it has AO.
  9. Had this PC server built a few years ago now, back then it was SOTA, but probably not now. Has a SOTM usb driver card which I think is playing up. JPlayer shows playback but no digital signal coming to Amanero usb-i2s . Its running Server2012. Anyone in Perth able to have a look at it for me?
  10. No problem, I just wanted to set the record straight.
  11. As the owner of Supratek, I think its a bit unfair to compare this very amateurish attempt at a power amp to one of my products. I know my practice of direct wiring in a seemingly act of randomness freaks out the anal types , who think that wires all bunched together and arranged in a 90 or 180 degree grid pattern is the sign of good sound. Fair enough were all entitled to our opinion, no matter how misguided or biased. I've never really bothered to put my side of the story, as it's mostly pointless trying to reason with the anal retentives, but this comparism is just too cruel. Hers a pix of the insides of my latest preamp, a LCR phono stage with matching line stage. Yes the wiring does look messy, but every one of those wires is in the best position to do its job, with the shortest amount of wire , in the best position to be un-influenced by other wires or components. Yes bunched wires all tied together look nice, but theres a price to pay in capacitive effects, and earthing issues, amongst many other things. The point to point wiring is rugged , easy to decipher, and does a far better job than a track on a pcb board . This is , afaik, the only moving coil cartridge capable LCR phono in the world . Getting a tube phono with such high gain to be quiet is a real task, and there's a lot of work and experience in the earthing arrangement - its also a complex and innovative circuit that is cutting edge technology . It would be a hell of a lot easier to just design a printed circuit board to mount everything on, but been there, done that, and there's no joy in that approach for me. PCB's are fine for non-critical tasks- you can see I've designed and used some in this pre, but i'd never do any of the critical signal wiring on a pcb. Also note the quality of components, there's no cheap junk and only 6 Silmic electro's, compared to just about any other preamp which will have up to a hundred cheap crappy electros in it. The chassis is made out of 1.2mm solid copper. So many tube preamps on the market these days are simple one stage , high output impedance pieces of crap. Open the bonnet and they may look nice, but you can be sure that profit is the main design criteria. I guess the gurus will come out again and say how bad this is, but i'd encourage a bit more open-mindness - its about the sound , not how neat the wiring is. And who's going to say the exterior is untidy?
  12. Just did a story on a dirt cheap server for around $100 -$200 on my blog www.supratekaudio.blogspot.com.au
  13. Yeah well the designer isnt exactly "conventional" either!
  14. I've seen the Melquiades circuit, looks quite interesting.
  15. Ok I dont come here too often, mostly because there are too many damn gurus here, but I can share what I do know about the 6C33C-B having used it for at least 20 years. Its a great tube, mostly because of its low plate resistance , much lower than a 300B , which means it needs a less complex output transformer and is capable of low output impedance, which gives it more oomph and results in a more linear frequency response into a speaker load. So it doesn't have the excessive midband accentuation common to non feedback 300B designs. This results in a clean , reasonably accurate sound not typical of your usual SET design. It can be undone by a less than capable driver stage as it does take a bit of power to drive it properly. The 300B actually makes a great driver stage for it. With a good driver stage it can put out a meaty 18 watts SE , quite a bit more than the 300B's 8 watts. Negatives- its hard to get matched pairs , they vary quite a bit from tube to tube, and consistency isn't great. They get bloody hot . They're hard to keep in bias, however a mixture of fixed and auto bias seems to tame that problem. I dont believe they're being made anymore, although I could be wrong. Plitron made some awesome output and interstage transformers for them years ago that could be used to make an extraordinary, and expensive SE amp, unfortunately no longer available , wish I still had some of them. Sowter make a good set of push pull outputs - built a 6C33C-B amp using them that made a great amp, and room heater. All in all, a damn good tube that does require some dedication to get the best out of it. The 300B is a lot friendlier in use , although its "romantic" sound when used full range can be polarising, which is subjective of course.
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