arco

Thanks both Mobile and Mdneen, As the former owner-modifier of this design, I could not have said it more extensively! Just one comment: I have very quickly discovered that this 4uF output capacitor selection was kind of a joke. The only think it did was to "muddy" things up. From previous experience, I know that each and every preamplifier circuit favours a particular value of output cap and, this, regardless of the power amp that it drives. With an AUDIO NOTE M7, for example, I know that the problems begin to get serious if you go past 0.22uF (Manufacturer's spec. and best choice: 0.1 uF). To cut a long story short, I stripped out the 4uF caps (the other ones, as well...) and - after experimentation - I chose to use 0.47uF VTV silver caps as my main choice (in and Hovlands of the same value in position A (very nice for rock-electric jazz). So, dear Max, the differences you are hearing have only to do with the different sonic characteristics of the output caps, not their different values. Aristidis www.aca.gr/pop_coumpas.htm

Mike, To reply to your main question: The first thing you look at is that the input impedance of your power amps is (at least...) 10 times higher than the output impedance of the preamp. This is the electrical side of things. Dont take it for granted, though, that two items that mate electrically will automatically play well (i.e. synergistically) together. To discover what really happens, here, there is only one method: Try the combination at home! I do not really believe that balanced connections have something particular to offer in a home environment. Moreover, there are very few really balanced (i.e. built that way...) components out there. The rest, just offers this type of connection, by using unbalanced to balanced transformers or other methods. One should keep in mind nevertheless that, in this marketing oriented hobby, a number of manufacturers actually "make" their equipment sound better, when this type of connection is used! As Mobile says, you are not near in finding a tube preamp with balanced connections in your price bracket. No big problem, but if you want to find out if the SM-70 likes better the balanced mode, you have to address yourself to the professional market and try to borrow a good quality unbalanced to balanced converter. SYMETRIX has a cheap and very good quality one (in blue, hope you like the color!). Aristidis www.aca.gr/pop_coumpas.htm

Horned, The particular cat, named Ponpon, sends you her photo and her love, asking me to tell you that she's so much addicted to her perfumed cat litter, that she would never ever dream using a vibration dampening device for other purposes! You can read the article by clicking on its description... Cheers, Aristidis www.aca.gr/pop_coumpas.htm

Horned: Bad taste the sandboxes? Arcici used to make sanbox stands for the notorious B&W 801's and they worked wonders. Thanks for reminding me! Fortunately, my 7 year old cat is Hi-Fi trained and - normally - wouldn't touch any piece of gear. I say normally, because once she jumped on my turntable while I was testing a Clearaudio Accurate cartridge. Murphy's law and the famous exception to the rule combined, but the Allmighty had mercy on me that night, as the cartridge (which was not mine!) came out unscathed... Ah, what an interesting hobby this is!!! Aristidis www.aca.gr/pop_coumpas.htm P.S. Mobile and the other guys:It goes without saying that you shouldn't miss to E-mail, before coming to this part of the world. All sybaritic pleasures, guaranteed (combined or not)!

Hi Max! Thanks for the hospitality and I must confess I am as happy as you with the results we had yesterday. Still, there is big room for improvement part of which can be attained with better amps as well as source components and another part, through a well thought out tuning of the system (like putting your equipment on inert bases and the like). It will be of course your responsability to decide where cost-effective upgrades stop and "diminished returns" start but - after what I saw last night - I can surely say I can trust you on this one. I mean that you let your ears (and only...) take the decisions, something not so common within the Hi-Fi afficionados. Many people, for example, would basically choose a component not on its sound merits alone, but because it is built like the proverbial brickhouse. Just one of the reasons why people prefer big chuncky transistor amps, over the more "frail" tubed ones, of the SE triode persuasion (wait till you see the VT52 1.3W/ch monster, I'm actually building!). Triodes and vinyl, you said? Here's what we will do: I will arrange a proper "soiree" with the necessary trimmings and you do the same, centered on SACD multichannel. Very interested to discover, if the main dish will be as good as the hors d' oeuvre I've already heard! Aristidis www.aca.gr/pop_coumpas.htm

Yep, Rebuilding with utmost care such a nice piece of equipment, just to install the lot in a rust pitted chassis is - in my humble opinion - like eating a lovingly cooked meal in take away cartons. The taste might be there, but half of the pleasure is gone! Don't get me wrong, though: I am actually myself in a building spree (again...) and I just get crazy seeing the costs pile up! I reckon this is a very personal decision, but I think you will not regret a nicely made chassis for your project. Aristidis www.aca.gr/pop_coumpas.htm

Justin, Just in case you find another gem in your garage... http://www.classic-audio.com/marantz/mindex.html Cheers, Aristidis www.aca.gr/pop_coumpas.htm

Hi there, If you need a new ***** and span chassis for your project, you might want to visit: http://cf.geocities.com/qltysnd/pages/frameset.html You then go to "Our products" and "ST-70 Dynakit" Have a good day, Aristidis www.aca.gr/pop_coumpas.htm This message has been edited by arco on 03-01-2002 at 02:34 AM

maxg, I have two items for sale that could be of interest to you: 1) My version of Doc Bottlehead's "Foreplay" preamp with constant current source upgrade, Sowter 230V transformer with electrostatic screen, Hovland caps and Noble potentiometers and 2) A DECWARE ZTPRE with beefed-up 500VA power supply, DACT stepped potentiometers and VTV silver output capacitors. You can have a first look at those by visiting www.bottlehead.com and www.decware.com Aristidis www.aca.gr/pop_coumpas.htm This message has been edited by arco on 02-27-2002 at 03:51 AM

Mobile is correct... Just keep in mind that some 300B tubes (WE included) need more than 200 hrs to sound their best! If you ever decide to "shorten" the break-in time by leaving the amp playing continuously, just remember to shut it off from time to time. Tubes also need a number of complete thermal cycles to properly set-in. Aristidis www.aca.gr/pop_coumpas.htm

Nice post Mobile! If you still want to use the SM-70 with your tubed preamp, I believe you could insert a good quality 33k resistor (say, a Caddock) in line with the signal and shunt to ground with a 10k resistor of the same kind. You will have no loss in quality whatsoever, although you can always play with resistor values to exactly match the gain of your preamp with the input sensitivity of the SM-70. Nevertheless, I have found those values to work well in many different cases... Happy listening, Aristidis www.aca.gr/pop_coumpas.htm

quote: Originally posted by edster00: On the subject of tubes, does anyone have any experience with "TJ Full Music mesh plate" tubes? These are being offered on AudiogoN and through Sophia Electric . I am particularly interested in the 274B tube that is supposed to be a direct replacement for the 5U4GB, 5AR4, and 5R4 rectifier tube. Any advice/information? TIA! Edster, The original WE274B is scarce and extremely expensive (up to USD 600/tube). WE plans to manufacture it again but I wonder when and it will still be expensive...VAIC also offers a 4pin 274B replacemant. I have not heard any of these tubes, but I do own chinese made replicas (the ones you have been offered...). My humble opinion is that they are nothing special compared to good quality US made rectifiers like, for example, Tungsol 5U4G's. Still, I think the Mullards are the best of all and very reliable too. Try them and you won't be sorry! Aristidis www.aca.gr/pop_coumpas.htm

For some reason, the file did not upload in the previous post. This time I might be luckier! A.

Hi, The attached file is from the "Kenyon Engineering News" November 1936, and shows that the Blue Glow question has been around for a long time. Aristidis www.aca.gr/pop_coumpas.htm This message has been edited by arco on 01-30-2002 at 03:13 AM

Hi everybody, O.K. so you have convinced your wife (or significant other self) to accept the big boxes in your everyday environment, but what about her also agreeing to the purchase of those uh rather expensive tube monoblocs you fancy? Well, if the difficulties seem unsurmountable, the French real masters in wife persuasion have just produced the MOZART monoblocs! Not cheap @ 1142 Euros/piece but they seem to be a well thought out and serious piece of work. No idea on how they sound, athough they should be practically noiseless, given the specs below Technical specs: Chassis: Specially made from brass and heat resistant glass. Power trans under the handle! Dimensions / Weight: 180x180 mm / 8,5 kg each Operation: Class A SE, no NFB Tubes: 6C41C Triode (output), EC86 and 5965 (input) Power/8 Ohm: 15W S/N (unweighted): 93dB Input sensitivity: 2,2V/full power Power Supply: With 2 Pi filters and 1800uF filtering capacity Have a nice day, Aristidis www.aca.gr/pop_coumpas.htm

Mobile, You cannot find the link because thesite has since changed its contents. But I discovered I had kept this text in my files. Here it is: Short Question -------------- What is the best biasing for KR 2A3s? Long Version ------------ I have built a pair of Paraglows with KR2A3s. They were built with the "snubbers" circuit either side of the rectifiers and had an extra LC stage (7H & 470uF) to the PSU. The result was a low supply of 380V, 372V at the 2A3s anode and a poor sound (IMHO). I then changed the 2.5k cathode resistor for the 3K one that comes with the kit for use with the standard 2A3s and shorted the additional PSU choke, keeping the additional C. The result was a higher supply of 395V, 377 at the anode, 235V anode-cathode, -39V grid-cathode on the 2A3 and a waay better sound. I am now wondering if by increasing the supply even more the KR 2A3s could be better biased and if so what I should be aiming to get. I have gathered that the "classic" 2A3 bias point is 250V anode-cathode and -45V grid-cathode but as the kit supplies a lower cathode resistor for the KR2A3s (2.5k instead of 3k) I'm presuming the biasing for the KR valves is different, in which case what is it? TIA, Neil (J Mackie). Aristidis www.aca.gr/pop_coumpas.htm

JBryan, Thanks for your input. I believe the SUN might be noisy because of its very high input sensitivity of 0.2V (and also apparent high gain). This combined with the KH's 104dB and a preamplifier with gain can break havoc indeed! With my previous preamp (chosen ad hoc), a DECWARE ZTPRE, I had no noise problems at all. With my current Hovland, I have built an input attenuator using Caddock resistors, with the same results and no loss in quality. I myself very much like SET amps and I will continue using them. What I tried to pass as a message is that for someone like me (big room, many different kinds of music...) the T16 is the best allround amp (i.e. the most versatile) for my tastes and needs. Its, in fact, the amp I would take with me in the proverbial island! But you should take this only as an academic assessment. Perfection is not of this world and I am not at all ready to dump all my other amps for the T16! Aristidis www.aca.gr/pop_coumpas.htm

Mobile, Being quite sure that I read about my mod in DocB's site, I took out a Ron Welborne catalogue from the time he was the US KR representative. Apart the understandable commercial bla-bla (The KR is by far the best etc...) he also refers to your mod. Well, I'm no tech, but I can surely understand that the removal of R13 augments the plate voltage to take into account the better ruggedness of the KR tube. Hence the increase in output, as the OT is driven harder. And, yes, if you play a normal tube under this stress, its life should be rather shortened... What I was talking about was a modification of the value of the cathode resistor which, by the way, is always shunted to ground (in our case the R10). And here we have the enormous problem with the so called "boutique tubes", which are sold as direct 2A3 or 300B replacements but, in fact, they are not. And their manufacturers say nothing about it. Against their interests, I believe. Anyhow, I already told you that before the mod I also found the KR lacking in more than one domains...Not after. I will concead that we are not talking here about the most romantic of tubes, but in no way I would call it soulless. I will try to find a pair of Sovteks to see better what you mean... Aristidis www.aca.gr/pop_coumpas.htm

Audry, I am a tube guy myself, but I do accept the fact that there are some very good transistor amps out there... But I digresss...Your problem is not really a tube vs transistor issue. You could in fact hear both and take a decision based on a mix of different factors(sound, practicality, price, opinions) etc. The real problem is that - whichever the amplifier technology chosen - your system must function properly, as a whole! And the best judge for that are your own ears, i.e. you must really like the end result. System matching is indeed a very complicated issue, but your ears will never lie to you. Trust them and you won't be sorry! Those are my two cents... Aristidis www.aca.gr/pop_coumpas.htm

quote: Originally posted by JohnR: 6C19pi can be obtained from Europe for $3 each. You can't post this information on Rozenblit's forum because he deletes it. JohnR JohnR, Why don't you share that info here? From my own (nonexhaustive) research, it appears that the European retail price is a little less than USD 9/piece. I have also discovered some russian sites with better prices, but then one must buy at least 100 tubes at a time (would consider, if I had to retube a SILVAWELD 150!)...But USD 3/piece retail, appears to me as an "out of this world" price, unless if we are talking factory seconds, here. And I wouldn't like to install this kind of tubes in an OTL (or any other...) amp! Aristidis www.aca.gr/pop_coumpas.htm

quote: Originally posted by mobile homeless: The KR is the most unmusical 2A3 I have ever heard. Quiet as a tomb...but as soulless as a loaf of Sunbeam bread. kh Mobile, Quiet as a tomb it is...but soulless? Well - using the KR as a direct 2A3 replacement - I had exactly the same opinion as you. Until I discovered in the Bottlehead site (they were then selling those tubes...) that - for cathode bias amps - the value of the cathode resistor should be changed (from 2 to 3k, if memory serves me well...) for this tube to perform properly. So I did change the value and that made all the difference. In my other amps where the bias is set manually, this particular problem is nonexistent. All one has to do is to set the bias in such a way, as to find the "sweet spot" of the tube. No problems, thereafter... If you performed this mod and you still found the tube to be soulless, then I might have not stated boldly enough that the synergy factor in our hobby, is more crucial that one might think. I do not have extensive experience with many different types of 2A3's but, extrapolating from the implementation of other tube types, I do know that some tubes work wonders in some circuits and almost crap in others... But, then, this is why hi-end audio is so interesting! Aristidis www.aca.gr/pop_coumpas.htm

Hi Tony, Here's the amps FYI: 1) SUN AUDIO SV2A3 with KR output tubes, Sylvania brown base 6SN7's and Tungsol 5U4GB rectifier. 2) SUN AUDIO 300BTE monoblocs with JJ 300B's, Mazda 6V6's, RCA black base 6SN7's and RCA 5U4G rectifiers. 3) Home made 2A3/300B monoblocks with VAIC VV30B output tubes, Western Electric 2C51 drivers and Mullard GZ33 rectifiers. 4) Yves Cochet ALS2 6L6 PP amp with GE output tubes, Tesla ECC82 drivers and Brimar ECC81 phase splitters 5) Plinius SA-100 MKII class A transistor amp. All the above driven by a Hovland HP-100 preamp. Cables are Nordost SPM and Clearaudio Clearline (speaker cable) Aristidis www.aca.gr/pop_coumpas.htm

Mobile, I was thinking exactly like you but, for some time now, something also "told me" I absolutely had to try that thing...Specific system synergies aside, the T16 hit the sweet spot with me, because it plays music with refinement and aplomb at the same time. And this, never trespassing the borders between analysis and musicality, if you see what I mean. Just imagine a 2A3 amp with balls! According to the manufacturer, the output tubes should last for thousands of hours (we will see!). Anyhow, the replacement cost is not that prohibitive, taking into account that a 6C19P costs about USD 9. To drive the lot, finally, I am using a Mullard CV4004 (12AX7 eq.) followed by a Philips ECG 12AT7 and a Sylvania 6189 (12AU7 eq.)x2. The Philips tubes were provided by TS, but not the rest of them. Those included were chinese 12AU7's and EI 12AX7's. Have a nice day, Aristidis www.aca.gr/pop_coumpas.htm

Hi Everybody, Sometime ago, I posted a topic asking if someone had any experience on Klipsch speakers and TS amps... Well, nobody could help on that matter. So (driven by an irresistible instinct!) I decided to take the plunge and be the first...guinea pig, building their USD 1099 (+USD 60 for the low-noise mod), 2x15W T16 OTL kit. I still can't believe my ears, because this might be the all time best-overall amp my Klipschorns have ever met! And this is what one should call a "documented" opinion, as I have compared on the spot the T16 with my other amps, which range from 2A3/300B SE to tube push-pull and transistor Class A. Very good amps as they all are, the T16 proved the only one able to combine this "inner lighting" and clarity SE triodes give to reproduced music, with the guts and utter control which are the realm of good transistor amps...And all this without sounding a bit clinical, mechanical or whatever you may call it. In other words, its a beautiful music making machine. And it sounds good right out of the bench, although it really comes into its own after about 50-60 hours of break-in. And I should not forget to tell you that, yes, it is silent...as a tomb! Last but not least, the kit is very well thought out and rather easy to build, even for the less experienced amateur. You can always buy it factory-built, if you so desire. That'it...If you are in the market for a good amp dont forget to check out this one by visiting www.transcendentsound.com Aristidis www.aca.gr/pop_coumpas.htm

I would tend to agree with Mobile on compression issues regarding most music played by today's FM stations. Soundwise, CD is much better and if one has to listen to the radio just to pass time or for informational purposes, he can do so with a very cheap tuner + int. antenna. BUT: The real sport, here, is to find stations that transmit live musical events directly. I myself am a tuner fanatic for that reason and only (own a MR71 a Revox B261 and a Sony ST770ES)and I can assure you that once you hear such an event on a good machine, CD is pale in comparison... You can, of course, always record it on DAT or CD for repeating the pleasure! Is the cost for indulging in such a pleasure high? Well, yes and no...If you want to buy the best in actual production tuners, then yes the cost could be high! Do not forget, though, that some of the best machines ever built are the analog tuners of yore: McIntoshes, Heathkits, Scotts not to mention well regarded items from European or Japanese manufacturers. Many of these tuners you can buy for a song, provided you know a dependable tech who can upgrade and align them correctly. The cost, finally, for a good (eventually directional...) antenna might be on the highish side, but then again that will depend on your geographical location vs the stations you are interested in... Those are my two cents... Aristidis www.aca.gr/pop_coumpas.htm