arco

Hi, Some years ago I had a correspondence on 6SN7 tubes with Dennis Boyle of Chimera Labs. He has sent me an interesting analysis (attached for your info...). Owning myself 4 of his references, can't say I agree 100% with his findings, but then the sound characteristics of a particular tube usually vary according to the circuit as well as the rest of the system... 6SN7 Sound Perfomance.txt

Well, until you train her accordingly (i.e. never to touch dad's KT88's and Hi-Fi gear in general...), you can always put in front of the rack a nice wiremesh (you know, the kind people put in front of their fireplaces!). Of course, your wife might not be 100% happy with the proposed decorative solution, but you can't have your pie and eat it too! Unless she buys that this hum lowers alarmingly your testosterone levels... Another solution is to dump the Tsakiridis amps and buy gear with shielded transformers. It will work but, this time, you pay the price!

When you are done with all that and still have problems, you might also want to try Mr. Sakuma's solution: You use two earth points on the chassis, i.e. one to ground the AC (better through a 10 Ohm / 2W resistor) and power supply grounds and the other for the signal grounds.

Put the TV on a proper stand with a shelf and place the two monoblocks underneath...

**** happens!

Dubai, If you go for a blind purchase, at least see that the chosen unit offers you some flexibility in altering input resistance and (less important...) capacitance. Last but not least, why not try the DACT CT-100 (www.dact.com)? I own it, so I can certify it's an excellent phono stage with maximum flexibility and costing a pittance! Of course, you have also to build (or buy...) a power supply for it and also put it in a box. Whatever...It will still cost a pittance compared to the competition and this, without performance compromises. Just see the "ABSOLUTE SOUND" test - among others - in their site, to be convinced.

Dubai, The T30 is obviously a good piece of work to which, one could add - among others - items made both by DENON and LUNDAHL (in Sweden...). But in this "trickiest" form of Hi-Fi synergy a good transfo is the one that best mates both with your cartridge and your phono stage. Just to give you an example, I once heard the really excellent results the DENON DL-103 cartridge (which is low output indeed...)could give, mated with a transformer DENON used to make specially for that model. Being myself a DL-103 owner at that time, I quickly bought the trans which in my system, combined with my phono stage, almost "robbed" the music of its dynamics!!! That's what I call "Money down the drain"... To cut a long story short, I would strongly recommend that you let your dealer do the job for you, until you are happy with the end result. You can then pay the asking price, knowing that it will anyhow be lower than the cost of doing the job yourself. And, best of all, without the psychological strain implied by this kind of adventure!

Dubai, Transformers can be made flexible (as some AN models) but this is a question of multiple primary windings and not resistors. Given this fact, apparently your supplier wants to introduce resistance between the first gain stage (i.e. the transformer) and the second (i.e. the tubed phono preamp...I have never personally tried this solution but I know from experience, that correctly mating a MC cartridge to a step-up transformer can be a very tedious job. So, I believe that if your supplier's solution does not give you full satisfaction, you might keep the second gain stage and try other step-up solutions (transformers or active ones). Good luck,

Nice work Dean! Carl Marchisotto should be more than happy if he ever saw these pictures...

Hi Max and many many thanks for being such a good host! What happened (finally...) to the food stock and all these beers?

test

Edster, Here's a site where you can find many BRIMARS... http://www.watfordvalves.com/mainindex.htm

There's another thing, one should consider when bridging amps, i.e. that the bridged amp becomes very dependent on the impedance curve of the loudspeaker. For most bridged amps, each time the impedance goes lower than 8 ohms the sound quality gets a serious kick! Too bad, as there are very few speakers out there (yes, even 8 Ohm ones...) that do not dip lower than that in some parts of the spectrum. Even if they dip down to 6 Ohm, they are still considered - by general acceptance - as 8 Ohm speakers. So, you might well quadruple the per-channel power of a stereo amp if you bridge it, but at a price! I would personally opt for a real monoblock amp, specially built to drive HT channels. Marantz makes such monoblocks. Cheap and cheerful (especially if you find a used one...) and not bad at all sonically speaking.

Yes I did... As I reported in another topic, my specimen worked flawlessly without buzzes or other irritating noises and the sound was indeed amazing for an amp that cost so little in its time. Amazing in the sense that it had this typical EL84 bite in the bass and was very balanced throughout the spectrum, although with a slight veiling in the upper mids and highs. I did not have the time to measure the tubes (all Mullards...) yet, but my instinct tells me that if I clean it up well and I do a step by step restoring, I might well be in front of a big surprise. I intend also to see if the preamp circuit can be bypassed so I can also use it as a power amp. As I am now fine-tuning the 45 amp, I think that the HF-81 will receive my attention during the forthcoming winter. Then I will surely come back...

CV4004 is the British military designation for the 12AX7 tube. You can go on and substitute your tubes without worry...

Max, Unfortunately, there are no 300B monos in there. Most of this equipement was made at a time when power triodes were considered rather obsolete and pentodes ruled. My former proposition to organize a 300B demo at your place, still holds if you are interested.

NOS 440, Thanks for that bit of info! I was looking for ages for a HK Citation II power amp and this guy has two of those...Let's now see what the final cost would be for one of these beauties to land safely in Athens, Greece (Brrrr!)

Max, After what happened with Tony's Accuphase, I am still more adamant on my belief that the only worth-to-have jap equipment is of the SET persuasion!! Good gracious me, I'm only joking...But I would have to win the Lotto to be able to buy an A50V 2x50W Class A behemoth for my KH's. But, then, what a perfect synergy... See you on Sunday,

And the expensive solution! Buy a used Nakamichi TX1000 record player which has a self centering record mechanism (photo attached) Cheers,

Max, You said it yourself:"Properly done...". Now, this - apparently simple -"Properly done..." is not simple at all! 1)Even easy to drive speakers can be very selective as to the rest of the set-up and the room and 2)You can create a technically correct (i.e. balanced...) stereo system and still not like the end result...Why? Because you cannot really communicate with music through it. To cut a long story short, my humble opinion is that to reach audio nirvana takes time and - unfortunately - there are no ready made recipies that apply. On the contrary, reading or exchanging views on the subject is very helpful in determining one's criteria i.e. what to try and what to avoid.

Audioreality, The only thing that could support the theory of the "stronger" tube watt, is that tubes have much smoother clipping characteristics than transistors. That said, you can overdrive (whithin reason!) a tube amp, without great sonic penalty...

Methinks I had a technical problem! Here's the reply: Max, You always need to double amp power for a 3dB increase in SPL and this, regardless of speaker technology or sensitivity. If, for example, you need 0.25W for a given SPL, at a certain point, with a sensitive speaker, then for SPL+3dB you will need 0.5W. With a less sensitive speaker, you might need 40&80W for the same result. So much with the theory... Yes, but of which speaker are we talking about? Because, you may have a, say, 91dB/W/m speaker with such a complex impedance profile (i.e. strong phase shifts, goes down to 1Ohm in critical parts of the spectrum etc) that no tube amp, which is essentially what we call a "voltage amplifier", will be ever be capable to do it full justice. Here, you absolutely need a transistor amp able to deliver high current into low impedances and - believe me - only some of those have the necessary capabilities. I have seen a 2x250W Rotel Michi power amp unable to drive a pair of Apogee Ribbons. Something an YBA2 HC did easily with only 2x50W! I could go on and on... It is, indeed, a very complicated world! That's why "Try before you buy" is still the best advice one could give for all things audio. I surely intend to visit you on Oct. 20. But please give the vinyl to Tony, as I would like to give it a listen on his system. Thanks!

---------------- On 10/10/2002 2:48:55 AM maxg wrote: Yes - a lot off questions - and it is a bit difficult to answer them all. I suppose the best place to start is how watts translate into db. The basics are that for every 3dB jump in volume you need to double the power. Starting with your speakers as the basis (99 dB/w/m): 99 dB - 1 watt 102 dB - 2 watts 105 dB - 4 watts 108 dB - 8 watts 111 dB - 16 watts 114 dB - 32 watts 117 dB - 64 watts 120 dB - 128 watts From memory your speakers in common with most Klipsch models can handle upto 100 watts continuous / 400 watts peak. Therefore the maximum continuous volume your system is capable of producing is theoretically about 118-119 dB which is ear damagingly loud for exposures beyond about 10 minutes. I should add that these are the ratings in an anechoic chamber at a distance of 1 metre. For every metre further away you can reduce the dB by 6. Therefore if you are sitting 3 metres from your speakers with 32 watts comming from your amp you should be listening to music at something around 102 dB or thereabouts. In my language 102 dB is plenty loud - far louder in fact than I would ever listen to music. The highest figure (continuous) in my listening position I use is about 90dB and then only when the wife and baby are out and only for rock music. (Note - there are others on this forum that will laugh out loud at that figure but I am keen on retaining my hearing for the foreseeable future and imho they are taking a risk). As most of my listening is done at about 84 dB, even taking into account I am 3 metres from my speakers you can see that with your speakers I will be running at 96 dB from a distance of 1 metre or 0.1 watts from the amp. This is where the advantage of tubes comes in. At outputs of less than 1 watt it is generally accepted that tubes are less distorting than SS amplification. The issue is not that a 3 watt tube amp will play louder than a 3 watt SS amp (if such a thing existed) but that for the majority of normal listening the tube amp will suffer less distortion that the SS amp. I should add that some makes are notorious for over-stating their outputs. Just because a given make of receiver is declared to be 100 watts does not mean that it actually is. There appear to be a variety of tricks the manufacturers use to make these numbers look bigger as watts sell amps. In summary a 3 watt tube amp will not play louder than a genuine say 30 to 70 watt SS amp. At 104 dB it will probably clip like the devil on the peaks, but, at levels of, say 95 dB it should sound gloriously better. ---------------- Nice analysis, Max, only you tend to forget two important things:1) Speakers (yes, even the most sensitive ones...) transform the bigger part of amplifier power into heat! 2) That said, one should also add that an important part of - almost any - music are transients. And correct reproduction of these transients demands huge amounts of power for very short periods of time. Hence the "school of thought", recommending the use of sensitive loudspeakers with powerful amps, for best reproduction of music in the home. Of course, like in every thing Hi-Fi, what you choose to drive your speakers is (and, I am afraid, it will always be...) a matter of personal tastes and priorities. An 250W/ch transistor amp coupled to a pair of KH's, will never have the magic and "inner light" of a small SET, although it could be expected to do bass and dynamics better, than its smaller sibling. And, of course, there are innumerable "middle of the road" solutions out there. Last but not least, sensitive loudspeakers in addition of having a big headroom combined with low distortion, offer their proponents the flexibility of being able to audition, say, Shirley Horn on a 45 amp and Mahler's symphony of the thousand on a x100 more powerful amp. That's exactly what I do! But I digress: Just put a dB meter in your listening position and try the music you like best, played by different amplifiers. You will quickly discover that the amp finally chosen (if only one!), will be the one which most satisfies your personal criteria. Not the theory! At the same time, another person will very probably choose an amp with quite different characteristics and be as happy. See you next week,