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My post about replacing the 6DJ8 cascode tubes has met with an undeniable truth....I am blaming the wrong tube.Currently I am running 4 Golden Dragon 12AX7 tubes which really are great all around performers. But in my preamp they give me a warm euphonic midrange, medium crisp bass and great highs.
I am seeking a dry and airy 12AX7 tube to see how that rolls....
Any suggestions on which brands I might roll?
Cheers.
Follow Ups:
Hi.Tube rolling is one 'passive' way to change the overall sonics of your rig. At the end of the day, you may end up with plenty redundant tubes in your waste bin, & getting the sound somewhat but not exactly what you want after spendimg a bundle. Do I sound like a wet blanket ?
My make of AX7 may sound totally something else when put into your amp. So much variables involved there. Who knows the right answer?
But who wants to trial & error without knowing the proper direction?I suggest you post your schematic & let us have a close look at it to see if something can be done in the circuitry to change the sound that way you like.
Let me quote you my experience.
Just like what inmate ShiFtY1000 posted below, the 50-year-young Telefunkun AX7s (ribbed plate with a square embossed at the tube bottom) in my upgraded PAS-2 phonostage sound very much what you like: airy, 'crispy', virbant, transparemt. lacking the 'warm' euphonic colouration, but pretty fluid, not 'dry' at all.
But before I upgraded my preamp, the tubes sounded 'aweful' to me: 'smoggy', slow, life-lacking, 'warm' & detail lacking. Totally 'out to lunch'.
Knowing it was the design issue, I did bypassing the entire input rotary switch, bypassing the entire tone-control linestage, & tapped the phono signal directly out from the RIAA O/P end.
Believe it or not, the original vintage TFK 'AX7 tubes sound totally
'something else' as what I described above - that is exactly what I love.Sonics depends on the cirucuit design so much.....
Good listening
cheap-Jack
June 20, 2005.
Yikes.....Last night I pulled out every 12AX7 I have in my miserable domicile, actually my place is very nice, but the miserable domicile description lends my apartment some ambiance....
I came up with 4 National branded tubes, 4 Precision Fidelity tubes which are the GE Gray Long plates with 4 holes, and 4 Golden Dragons.
The first stage of my Cascode preamp runs 2 6DJ8 tubes and these appear to be National brands but I am not sure. I took photos and will try to get an answer.
First I ran 4 Golden Dragon 12AX7's.
The sound is very lush and full. The GD tubes are copies of the Mullard 12AX7's and as such are designed to give that fat, full bodied sound to instruments in the midrange. However the bass is a bit plump and round. Too much of a good thing. And overall the sound just seems to be "compressed" so the height, width, and depth of the soundfield is all between my speakers. This is the sound field I expect from transistor preamps. So the GD's get my recommendation for awesome timbral accuracy and poor for 3 D soundfield reproduction.
Next I ran all GE long plates with 4 holes. These are private labeled Precision Fidelity tubes and I cannot remember if they came from the front end of my M7A Dual-Mono Amplifiers or if they came from the C7.
Wow.....When I asked for a Dry and Airy tube to roll one respondent mentioned this tube as a good prospect. Dang this tube is hot and fast. This is like Star Wars or Star Trek...like going from regular speed to warp speed. Midrange goes wide and deep and the highs are blazing.
Problem is that the timbral accuracy just implodes. It is as if you have an awesome sounding system with a subwoofer, and someone turns off the frequencies below 200 hz. Too bad for me. Here was the dry and Airy quality I was after, but it shifted the sound way out of spectrum.
Next I tried 4 National brand 12AX7 tubes. Interestingly this tube did nothing wrong, but very little right. Get it? It was like midway between the GD tube in bass, and midway between the GE tube in highs. However the sound was just blah.... The best description for the tube, it likes being midway.....
Now comes the fun stuff. I tried variants on a theme. I tried the GD's stage one and GE's stage two, Then the GE's stage one and the GD's stage two. Then I substituted the Nationals with the GE's and the Nationals with the GD's.
I rolled thes ol tubes ....4 hours or so.
My favorite combination for dark sounding LP's is the GD stage one and the GE stage two. This gives me timbral accuracy in the midrange and razor fast transients in the midrange and highs. But way too hot for a quick record.
My favorite combination for hot sounding LP's is the GD stage one and the National stage two. This gave me timbral accuracy with a less aggressive mid and treble range to help calm those pesky bright albums.
You guys have ruined me....
I still do not have the sound perfectly tuned. I need some tubes that have the timbral accuracy of the GD's but without the compressed soundstage. And I need a Dry and Airy tube that is not as shrill as the GE.
So now it is time to break out the check book and buy some more tubes.
I guess I will have to try to find some Siemens Teles, Telsas and Amperex to see if I can coax out a more perfect sound.
Such agony, such pain, and such pleasure when you know you are getting OH SO CLOSE to audio nirvana.
Thanks for all the great suggestions.
"Dang this tube is hot and fast. This is like Star Wars or Star Trek...like going from regular speed to warp speed. Midrange goes wide and deep and the highs are blazing."
I mentioned this tube, because it is one of the best 12AX7 made ever. But, if you compared this sort of sound to the real live performance, you would have to consider that this tube sound wouldn't be airy enough!
Why do I think so? I have visited more than 200 orchestral performances over the last ten years. I was shocked every time , when I came home and ran my amps after live concert. Dull, boring, slow. The real thing was fast, dry airy, explosive... E.g. you can't hear bass, mid frequencies and highs divided from each other. The real thing is one part. Much more airy than you could imagine.
You could save a lot of money: Visit a live performance with a not amplified big band or orchestra. Take front seats, because the microphones are very close to the musicians. Then go home and listen to your system. You will be shocked, I promise you. And you will love your GE tubes and search for much more airy tubes.
You are a man after my own heart.....I am a musician first and foremost. I have played Piano, Clarinet, Violin, and Viola since I was 5 and that was 43 years ago. I know the sound of live music. Right in the pit of the orchestra. I also know the sound of live music as a listener in the audience.
I so totally agree with you. Live music is so much different from audio that we spend time and money to perfect.
I did love the detail and magic of the GE's. I can see why Precision Fidelity choose them as their tubes in this preamp. But all my modifications have been in silver. And pure silver is 30% more conductive than copper. I think the brightness and shrieky detail I heard were the effects of this detail exaggerated by the conductive qualities of the silver I run throughout my system.
Another asylum member has suggested that I pitch the National or Unknown 6DJ8 tubes and replace them with a known world class performing 6DJ8 and then listen again.
I whole hearily concurr.
The GE's are just really great at the speed, the naturalness, and the immediacy of live music.
They just lack the meat on the bone in my system because of the silver interconnects and internal silver wiring. So I need a better 6DJ8 and a better first stage 12AX7 and then with the GE in the final stage I should have the sound that I long for.
I really appreciate your responses. They are predicated on your knowledge of how sound is at a live event, and how the electronics reproduces it in audio gear.
Kudos to you. You are the best friend a fellow asylum could ask for in his quest to obtain audio nirvana.
Happy Fathers Day!
It is a pleasure to hear from you!
I am honoured by your appreciation.Is your silver wire solid core or not? Which sort of insulation does it provide? To my ears a thin silver solid core wire with teflon insulation shows the best results.
I have already given you a list of small signal triods which are very fine. I would like to add that this list results not only from my listening experience, but from my measurements as well.I am a little bit proud that after five years of study I can match my impressions from listing with measurements.
I am also very glad that you as a musician have the same goals in home reproduction as me. According to my experience there are many people who perceive tube amps in contrast to transistor amps and consider the weaknesses of tubes as their strength.
Now I would like to ask some questions:
At the moment I am evalutaion output tubes: I can observe some similarities to small signal tubes, but it is not all the same. I know very well the following tubes: KT66 GEC, 6550 ECG, 6L6 Viseraux, KT88 JJ, KT88 Chinese, 6550 Svet, 6F6 unknown, 6L6GC Tesla, all EL34 NOS and nearly all EL34 of current production, some 6V6 KT63, and last but not least German EL156 and F2A11.
I like most the Chinese KT88 within the range of beam power tubes and the Chinese EL34 and metal base EL34 Valvo within the range of the pentodes. Do you know I should consider?If you want to modify your circuit, I would be happy to calculate the correct values you need. Do not hesitate to give me a short notice.
I purchase my solid core silver wire from A-M Systems in the state of Washington. (www.a-msystems.com) This is medical grade wire for electrode use. It is drawn and double polished to be percectly round, smooth and stress resistant. It is annealed for flexibility. It comes either bare or teflon coated. The teflon coating is extremely thin.For interconnects and within the preamp I use .o25 inch wire. I use the teflon coated wire only if I am inside a preamp. Otherwise I purchase bare wire and place it in a teflon tube 3X the diameter of the wire so that air becomes the dielectric.
This sounds awesome and requires very little break in time to sound awesome.
For a tonearm, I use .015 inch wire with teflon coating. The wire and coating ends up .019 inch. It dramatically improved the sound of my modified Rega 250 arm. I removed its black carbon paint, mounted a Michell Technoweight, and place it in the awesome Peter Riggle VTAF. This stands for vertical tracking angle on the fly. So when I am playing any album I can listen for the point where the VTA is perfect. I am amazed that just a fraction of a degree can be the difference between magic and bland sound.
I will be drawing out the schematics the best way I can on my preamp since I cannot seem to find a manual for the C7A preamp. More to follow.
As for power tubes, my Precision Fidelity runs 4 EL34 Pentodes at an extra high plate voltage with current limiters set to 20 microseconds so the amp can deliver 400 watt peaks for 20 microseconds, enough for a cymbal strike. A kick drum, or whatever is presented. I am running 100 watts per channel strapped in mono.
The amps are tubed with Golden Dragon 12AX7's and Golden Dragon EL34's. The sound is gutsy, clean and clear since the M7A amps are hybrid. I like the hybrid amp because it is so fast in the detail department. The sound is very clear and very real. I also like Audio Research hybrids, but they seem to have an upper midrange emphasis that I never hear in live music, so I grow to dislike them in short order.
I have not tried much Tube rolling in the PF Amps. Just Teles and Telsa's.
I really like the sound of SET triodes. I have heard several models that I think are outstanding. But they require horn speakers to play at the volumes I sometimes reach. And horns are a real mixed bag.
My Cremona Auditor Wanna Be DIY speakers sound amazingly close to the Sonus Faber Guarnari speaker. I run two 12 inch sub woofers that sound very much like REL's but with more authority and more crispness. Bass should growl not moan.
Thanks again for the great postings! You are a credit to the asylum and I hope you can help me achieve the most out of this circuit that I can.
Cheers
Thanks very much for your informative answer. I do not see any necessity to roll the output tubes. The source of your silver wires is very interesting to me. I am using the REGA 250, too, and it provides outstanding sound quality together with Denon DL103. Compare my message above.Frank
On the 6DJ8 front, the only current production tube to consider (IMO) is the JJ E88CC. The JJ's sound is close to that of the W. European NOS that so MANY "inmates" favor. The JJ easily wins the price/performance battle, as W. European NOS 6DJ8 family tubes sell at very high prices.
Eli D.
You are right, Eli. Also my measurements indicate this as a matter of fact. My listening experience also conforms to this. However, I can bear a E88CC in a cascode stage, if so after all. It is constructed to reach up to 80MHz. That means that transconductance in relation to current is very high, but also the frame grid construction is not able to avoid a bad electron optics. This results in relatively high mu distortions. As the distance between plate and grid is small, the space charge is so, too. Therefore directly reflected electrons are not suppressed leading to a fine structure in the distortion pattern. Definetely not as high as in beam power tetrods, but still enough to be recognised as somewhat dark and back stage sounding.
If you do not need the low impedance of a E88CC cascode as the next stage does not have a high input capacity, a fine audio tube like 6 CG7 or the Chinese triple mica 12AU7 would be a better choice. In a first trial you could make a direct replacement of E88CC and 6CG7 because they are pin compatible.
Today I purchased some Amperex Buggle Boy 6DJ8 tubes and some Siemens 6DJ8 tubes to roll next. I am not sure about the Amperex but I hear the Siemens is very neutral and somewhat more linear than other brands. If I cannot get the sound I am after, then it is time to make sure my cartridge is loaded optimally.I am very intrigued about the 12AU7 tubes. 30% less power than the 12AX7. But I hear they may make a nice cascode preamp circuit. I have heard others comment about the 6CG7 as well. I do not know if this would require extensive reworking of my preamp or not....
I also purchased 4 12BZ7 tubes, GE Models. The seller says these are up to 30% more power than the 12AX7 so I may be willing to modify my circuit to get the higher gain. Then I can buy a low powered moving coil cartridge which is my future plan, and run it without a step up converter.
Here is the description of the 12BZ7's....
"From an audiophile's private collection, here is a remarkable NOS NIB matched QUAD of GE LONG CURVED BLACK PLATE 12BZ7 preamp and guitar amp tubes MADE IN USA in the 1950's or '60's. These are direct plug-in "big brother" replacements for the venerable 12AX7's. Three are labeled/boxed "GE" and the fourth is labeled/boxed "Zenith". It was actually made by GE (common practice back in the good old tube days). They have the SAME amplification factor (100), higher plate power dissipation ratings, can handle more power and therefore can be run at a lower percentage of their full capability which means their dynamic range is significantly better than 12AX7's in a similar circuit. My SAMS tube substitution handbook says that 12BZ7’s are great substitutes for 12AX7’s! All tested EXCELLENT on a TV-7B/U military tube tester."
I am hoping these will sound nice, if not, I will provide them to one of my Guitar playing buddies.....
Cheers.
They are not interchangeable with 12AX7- same mu, but half the rp, double the gm. Double the heater current, too. And much higher distortion, and high-order distortion it is.Give them to a guitarist- they don't belong in a hifi system.
"I am very intrigued about the 12AU7 tubes. 30% less power than the 12AX7."
The 12AU7 has got a maximum plate dissipation of 2.75Watts per section. A 12AX7 has got only 1Watt!
But I could only give a recomendation for the triple mica Chinese 12AU7. All others I know are not airy sounding.
Frank
Some tube families are easy and one can use any number of brands and get good sound. On the other hand some tube families are a pain with only a couple of companies getting it right. I consider the 6dj8 family to be a pain. So I would encourage you to start with having a known good tube is this location so as to be able to properly judge the 12ax7s. There is a FAQ section here with good info on the 6dj8 family. Personally I would go with a real Amperex or maybe a Siemens and wouldn't bother with any other brand to start with. Buy from someone good and stay away from places like richardson and national. Pay the bucks and get the real deal. It will save you time, money, and aggravation down the road. Beforewarned that they are many fakes floating around so again I caution you to buy from someone good. For something on the lighter side without being "warp speed" bulge boys should be a good, sound, all around safe choice. I think the siemens tend towards the faster side.With a good 6dj8 in place then you can move towards the 12ax7s with confidence that you are hearing them and not a crappy 6dj8. Telefunkens and Mullards have to be considered the top 12ax7s and are priced accordingly (but used). An older RCA blackplate is a very nice tube also. The best newer tube I have found is an Ei from a couple/few years ago but the current ones are very iffy.
I am sure some will take exception to what I say. There are a number of good tubes out there but when you are looking for the best then a few names emerge. IMHO you will have a much easier time finding a less than famous name 12ax7 that sounds okay but you won't have a lot of luck with second tier 6dj8's.
The above assumes you are looking for top sound. If you can't or don't want to spend as much for the 6dj8's and are willing to move down in sound quality I'd buy the EH6922. If looking to spend less on the 12ax7s seek out the older Ei.
Russ
I have purchased a pair of Siemens 6DB8's and a pair of Buggle Boy Orange tubes to try.Thanks for the recommendations!
I see both GE gray and Black plate triple mica and RCA black plate 12AX7's. Do you prefer one to the other?
This will be fun.
Cheers
Dang... I love this s t u f f....You have to love engineering and electronics to want to tweek in the audio arena.
I do love this so. Like Patton loved a battle. Like Einstein loved to inquire. Like Darwin loved to describe what he saw in nature.
Gray long tube GE's are just so awesome at detail I could not believe it. Really world class detail. Unfortunately I run silver solid core wire in my tonearm leads to preamp, throughout my preamp, and in all my interconnects. So any high frequency shift is now recreated as a high frequency nightmare. If I was all copper, who knows I might be a fat and happy pig right now......LOL
So the GE's sound so supreme but lose the timbral accuracy all together.
I totally agree with you that I need to start with the best 6DJ8 I can obtain. Cost is not an object here. I have over a grand invested in the preamp. And it sounds better than any Krell, Levinson or Classe Pre Amp I sold at thousands more. So what is a hundred or two to get this right.
I think your feelings are dead on accurate. Get the 6DJ8 settled and then listen again and make some final tube rolling changes.
I guess I was not expecting the variation on the sound I experienced last night. Such a stark and completely different sound was expressed by each of the three manufacturer's tubes I had on hand to evalutate. Mitigated of course by the contribution, or lack of, from the questionable 6DJ8 tube I am running up front.
This really is so much fun. The agony and the ecstasy is just a way to communicate how close I am to having it all. Great timbral accuracy. Detailed bass, midrange and upper mid range and crystal clear highs. When I have it all then I will be satisfied. Until then I am having fun doing all the ABX stuff to achieve nirvana.
Cheers!
By the way I think your responses to my posts have been AWESOME! Thanks for the fellowship!
Any old telefunken ecc83/12AX7. These have a very nice crisp sound, very accurate and not overtly warm. Probably exactly what you need. Don't be too afraid to buy used, these last forever...
Try a couple 12AX7LPS Sovtek. You've gotten a bunch of suggestions in both forums you posted this in, but all are pretty pricey and/or hard to find. You might be very happy with a set of Sovteks! For $25.00 you can hardly go wrong.
Other than the Sovtek 'LPS, the JJ "copy" of the TFK ECC803S is the only tube CURRENTLY being produced worth trying. The JJ is a TAD bright, maybe that would be good for you.IF (very big if) you can be ABSOLUTELY sure you are buying tubes made before the Q/C mess started, the EI ECC83 is an option. When they are made right, the EI tubes are a GOOD sounding close "copy" of the TFK ECC83.
If you are LUCKY, your equipment energizes the 'X7 heaters with "12" V. Should that be the case, then you have a highly affordable NOS option. GE built 7058s sell for under $10/tube. RCA 7058s will cost you more, but are still not priced very high. If you can use the 7058, do so. It's hard to argue about GOOD American NOS at prices that are highly competitive with current production.
Eli D.
Try the GE 12AX7 long plates with four holes in each side of the plate. They, the old Tesla E83CC yellow label and almost all of the 5751 triple mica tubes are producing the sound you want. I was looking for the same sound last two years.
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