maxg Posted April 27, 2004 Share Posted April 27, 2004 BACKGROUND Well I have just got back from Tsakiridis again - with the amp now perfectly setup and awaiting re-installation in my system. Why another visit? Did I fail in my attempts to bias the amps? Well - kind of.... With little trepidation I set about the job of installing the new tubes (Svetlana 6550C) to replace the EH EL34's. I removed the amp from its usual hidden location behind the TV and set it up, upside down in my office - with power supply, meter, screw drivers and tubes at the ready. Removing the bottom metal plate revealed in the innards to me - and I took a pic or two but havent got my camera with me - so you will have to wait for pics. Anyway just as I was about to start biasing away I noticed that the socket that had contained the failed tube was blackened, as was all the wood around it. Uh Oh. Quick call to Odyseus - we measured a few things - should be OK for a quick play - but bring it in tomorrow for a proper going over. So I closed the box - re-re-installed it in the system and fired her up. MUSIC After packing off the family to varous parts of the house and giving the amp time to warm up I listened to some old favorites to see if there was a difference from the EL34. First up the Rachmaninoff 3rd piano. Big. Very very big. Huge. Tangible mass to the piano and the bassy parts that I have never heard before - even with a sub. There is a lot to be said for 100 wpc but subtly isn't one of them. A completely differnt portrayal of the music. This is Wagner Vs. Strauss. Not necessarily better at this stage - but very very different. Switched to Beethoven 5th Symphony. Real mass to the orchestra. The music has weight and size aplenty, but the strings are a bit resessed compared to the El34's. Switch again - to a string only piece (Schubert). Sounds wonderful but with possibly slightly less air than the EL's made up for by the menace of the double bass. Opera - Rossini - Barber of Seville - similar experience with a couple of additional elements. Big girl that Soprano - I can tell - I couldn't before - I can detect her chins wobbling!! I suppose the summary would be the music is fatter in that there is a leaness to the EL34 portrayal that I would never have contemplated except in comparison to these. Sometimes that is a good thing, sometimes not. FIXING Anyway this morning I packed the lot in the car and headed to Tsakiridis' emporium. Damn that man is good. He changed out about a dozen items before I had had chance to remove my jacket. Snip, snip, solder, solder - test - reject - snip - solder - fix - test - accept. Nice!!! Then he biased the amp - roughly - checked some more stuff - then biased the amp again - accurately this time, waited 5 minutes and checked the bias again. Having done the job he put the amp into his system for a proper test. Sounded great - no hiss (first time for ages) but that may be the low sensitivity of the speakers - I will see tonight. Anyway I'll do another test tonight to see if the sound has improved over last night - I think it will have done. Whether it will address the issues in comparison to the EL34's remains to be seen. OF WATTS 70 or 100 - we are in the big league now - will have to decide which way to go, but not before I sample Tony's latest purchase. Yup - he bought the Yamaha 500 wpc digital amp. Hopefully we will have it by the weekend to play with. Should make an interesting comparison!!! Of course it may not be the ideal choice for those of you with 104 db/w/m sensitivity, but then again you are all so insane.... Quote Link to comment Share on other sites More sharing options...
maxg Posted April 27, 2004 Author Share Posted April 27, 2004 Just to add the details to what Tony is getting: http://www.yamaha.com/yec/products/components/mxd1.htm Doesn't look like much does it? That is an amp? With 500 wpc?? My god!! Quote Link to comment Share on other sites More sharing options...
Piranha Posted April 27, 2004 Share Posted April 27, 2004 And an MSRP of $4999.99. WOW!! Quote Link to comment Share on other sites More sharing options...
Parrot Posted April 27, 2004 Share Posted April 27, 2004 You could have had a catastrophe there, Max. A good anecdote about the perils of leaving amps on 24/7. Quote Link to comment Share on other sites More sharing options...
maxg Posted April 27, 2004 Author Share Posted April 27, 2004 MDeneen, I think you are right, but dont stop there. In theory there is no reason why you couldnt download playback profiles into a digital amp to make it sound like any amp out there. You could have 2A3 sound for example - but with 500 watts instead of 3.5... Piranha, I wouldnt worry about that retail price. Tony got the demo unit for 2000 euros - about $2500. It is a Yamaha after all!! Paul, Dont I know it. That is the formal end of leaving the amp on for me - although Odyseus swears blind it would have burnt though the electrical connections before a fire had a chance to start - he says it is designed that way (but he would). Having said that he doesnt recommend leaving amps on anyway, and if that is what the manufacturer says I will take his word for it. Quote Link to comment Share on other sites More sharing options...
Piranha Posted April 27, 2004 Share Posted April 27, 2004 I am looking forward to your reviews of the 500wpc digital monster Max Quote Link to comment Share on other sites More sharing options...
maxg Posted April 27, 2004 Author Share Posted April 27, 2004 ---------------- On 4/27/2004 8:41:50 AM mdeneen wrote: "In theory there is no reason why you couldnt download playback profiles into a digital amp" ---------- Right. This concept has been available even in analog guitar amplifiers for many years. "Modelling amps" can be set to mimic all the popular amps of history. Everything from the VOX to the Plexi to the Bassman and in between. If you merge about three ideas, you have it. The acceptance of downloadable .mpx music, the development of efficient digital amplifiers, and the computer as an 'entertainment hub" you have the whole future in a nutshell. I think that is the wrong way around. The entertainment hub is a computer. Actually it largely is already - just not using a standard operating platform. My DVD player plays MP3 from a CD reading it in the same way my computer does (displaying a listing of the files - even the directory structure) My iMac already has the TriPath amp in it, and access to iTunes. So, make the amp bigger, make it 5.1 or 7.1 or whatever all that is about, add "modelling" software, add wireless speakers all over, and voila, you point-pick-pay-customize and play whatever you want. For 90% of the public, this will be far better than stacks of cheap receivers and wires and records and CDs. Tri-path on your computer - wow!! I had no idea - have you played with it? How does it sound? Wireless speakers is not quite the panacea you might think. Remove the signal wire and you will need a power wire instead, which is probably going to be the amp - which messes things up a bit, even if it is digital. In all honesty I have no idea how far this all might go. I think this is potentially a bright future but the source material is more worrying - unless they move DVDa and SACD to "soft media" and we get the bandwidth to download them in real time. Right now the real interest is to see how this amp sounds. Tony is going nuts over it reckoning it will be the new standard of neutrality by which all others are measured. That seems to be their aim at the moment - but downloading different identities would be really fun. You could even make it behave like a 3.5 watter - clipping and all, then extend its range ever higher - till it successfully drives your 84 db/w/m speakers to 111 dB!! Quote Link to comment Share on other sites More sharing options...
dubai2000 Posted April 27, 2004 Share Posted April 27, 2004 Max, I am sure you must be glad that your amps are back and you know they have been brought up to specs again. BTW: among some of the tube gurus over here there is a saying that the sound you get corresponds to the looks of a tube, i.e. EL34 vs 6550 = slim vs fat....it seems your listening experience seems to support this view. I once had borrowed an Audion amp ready to accept both tubes. I cannnot remember which brand of EL34 were used, but I found there was 'something' in those GE 6550. The amp didn't stay long enough with me for a detailed comparison, so I cannot tell which I would have preferred in this particular amp. I think you'll have fun comparing those....and Tony's Yamaha. Wolfram Quote Link to comment Share on other sites More sharing options...
NOSValves Posted April 27, 2004 Share Posted April 27, 2004 Max, Glad you took the amp in and had it straightened out smart move and your supplier must be a top notch guy. I'll be very interested in all your testing and listening. Keep it coming !! Craig Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted April 27, 2004 Share Posted April 27, 2004 ---------------- On 4/27/2004 11:16:42 AM mdeneen wrote: Perhaps this is also an argument for not building tube amps in wooden boxes? mdeneen ---------------- ...or use resistors as fuses in a circuit, or put 4.5W on a 5 W resistor, or use resistors that are not flame proof. Or see it as an argument for using self bias. Quote Link to comment Share on other sites More sharing options...
maxg Posted April 27, 2004 Author Share Posted April 27, 2004 ---------------- On 4/27/2004 11:16:42 AM mdeneen wrote: Perhaps this is also an argument for not building tube amps in wooden boxes? mdeneen ---------------- Or for not building Tube amps at all. I am starting to realise quite how dangerous these things can be. Looking at it wood probably doesnt seem like the ideal material to bass an amp on - and it is noticable the newer designs are moving to metal chassis with wood relegated to decorative touches. The thing that surprises me most is that there are 3 fuses visible on the outside of the box - and who knows what on the inside - and yet it still burned (well singed more properly). Maybe the risk of fire was not as great as it appears on first site. I am not one to pass judgement too quickly - but if a digital amp comes out with tubie sound.....I am there! Quote Link to comment Share on other sites More sharing options...
maxg Posted April 28, 2004 Author Share Posted April 28, 2004 This is the interior shot of the powerhouse that I have promised months ago. I thought I would post it here rather than in a new thread - hopefully people will find it and be able to comment. You can clearly see the burned area - so judge for yourselves. It does look a lot better now - but still singed. As it happens I connected the amp up yet again last night and it sounds totally different. I'll hold fire on a comparison review but most, if not all, of that flabbiness has now gone. There is a lot to be said for ensuring your amp is properly setup and balanced, biased and the rest. On the subject of setup Odyseus set the bias on the tubes to what he says is a rather high 250 mV. According to him this means that the amp will operate longer in class A. Anyone care to explain what that? I didn't quite understand why. Whatever it means the amp sounds good. The verdict on whether it is ultimately better than the EL34's is still pending. It seems .... what .... less coloured? Quote Link to comment Share on other sites More sharing options...
maxg Posted April 28, 2004 Author Share Posted April 28, 2004 Thanks MD, I understood bits of that. If we add what I understood from you to what I learned from Odyseus I am now in a position to be very dangerous (little knowledge and all that).. I am puzzled by something though. Odyseus implied that the higher the voltage we were setting the longer we would stay in class A. If this voltage is resultant from the Bias shouldnt a higher voltage mean a lower number of amps (assuming the watts are constant). If so does that mean we stay in class A longer or the opposite? Confused! Quote Link to comment Share on other sites More sharing options...
maxg Posted April 28, 2004 Author Share Posted April 28, 2004 "So, clearly, the "higher" the reference voltage across the cathode sense resistor, the more bias, the longer you will be in CLass A." Got it - thanks. That is exactly what we were measuring. The 8 little plastic screw things in the middle of the picture are what we turned to adjust the bias - raising and lowering the bias current and, in turn, the voltage across the cathode sense resistor. Yippee!! Another one nailed!! Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted April 28, 2004 Share Posted April 28, 2004 This looks like art.....especially the coil windings.... K6 Quote Link to comment Share on other sites More sharing options...
KungFuNat Posted April 28, 2004 Share Posted April 28, 2004 mdeneen, please explain "tri-path" in your imac... amp modeling is one thing, tri-path is completely different. quite frankly this doesnt make much sence... Quote Link to comment Share on other sites More sharing options...
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