AudioCircle
Industry Circles => Audio by Van Alstine => Topic started by: avahifi on 27 Feb 2012, 02:50 pm
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Our new Fet Valve 600R amplifier is in the review process by a major audio magazine.
The reviewer has asked me if we have any favorite old new stock 12AT7 tubes we would recommend for this amp.
I can't answer this question myself.
So I am asking you owners to let me know which tube you like best in this great amplifier.
I will forward your responses on to the reviewer.
Thanks,
Frank Van Alstine
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Frank, I don't have a 600 but I do have an Ultra+ 550. I like Telefunken, I have both ECC81 and ECC801s they sound the same to me so I am running ECC81 they cost a little less.
:smoke:
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The best (in my view) is the Sylvania 6201 gold pin. Hard to find, however.
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Depending on the rest of the setup (speakers etc), TFK ECC801S, Valvo 6201 Blue labels, Siemens E81CC triple micas (may be a little too energetic depending on the speakers), Sylvainia GB 6201 - two or three mica (IMO three mica sounds a bit nicer).
Highly system dependent as I would hope the reviewer knows, although even I will admit the FetValve design shows less of a hot-cold change with tubes, compared to other tube amp designs. Still, different tubes will make a change which may be important to some listeners.
My personal choice with full frequency standard driver (cone, dome) speakers is the TFK 801S and the Valvo 6201 Blues - although since the Blues are pretty much unobtainium he/she should go for the TFKs first. In my system the TFKs provide the right compromise between transparency, extension, soundstage size, depth, and musical smootness. If the reviewer's speakers are a bit zippy or thin, the Sylvania 12AT7WA triple mica black plates might be better. Affordable too. If the speakers are a bit mellow and slow, I'd go with the Siemens E81CC.
The Sylvania GB 6201 is a fine all around choice.
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I'm bumping this back to the front in hopes of a few more comments.
The reviewer for TAS wants to know what are the best 12AT7/ECC81 tubes you have tried in an AVA hybrid power amp.
I would appreciate your comments.
Thanks,
Frank Van Alstine
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The reviewer for TAS wants to know what are the best 12AT7/ECC81 tubes you have tried in an AVA hybrid power amp.
No one else out there with experience in this area? We want to make sure Frank's amp gets the best opportunity for this review.
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Frank, ask the reviewer if he has any of the above tubes. If not, I can supply a pair of 6201 gold pin.
Regards
Aln
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The best (in my view) is the Sylvania 6201 gold pin. Hard to find, however.
I used 12AT7 tubes in a pair of VTL MB100 monos and the Sylvania 6201 gold pins were the best 12AT7's that i tried in that circuit. they are excellent US made tubes :drool:
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IME the great 6201's, e.g. Sylvania, Valvo, have a special, refined, finely-grained warmth which will fit many/most systems well. I personally prefer the Siemens EC81CC triple mica, which is not particularly "warm" nor "sweet" but extremely transparent with bristling microdynamic life that can sound so real it's scary at times.
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JJ 12AT7. I don't have AVA's best amp, but the JJ 12AT7 sound better than my vintage well known 12AT7 in my Ultra 550, probably because the amp has been designed around the JJ tubes.
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I tried the Telefunken ECC81 in my 400R, and compared to the stock JJ, I was not that impressed. The TFKs seem to mellow out the amp. The highs have less shimmer and detail and the sound sage narrowed. Just sounded dull to me. Much better with the JJ and the differences were quite noticeable after I reinserted the stock tubes. My pre is the Avastar using RCA Clear Tops.
The new PSVANE 12AT7s seem to have favorable on-line reviews. Any one try them?
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I have a Double 550+ and the NOS 1967 TELEFUNKEN ECC801S were quite a step up over the JJ's. My second choice was 1966 NOS SIEMENS E81CC and third were Triple mica Brimars from the '60's.
In my DAC and T8 I tried quite a few NOS 6CG7's including NOS RCA Clear Tops and eventually went back to the current production EH.
Interesting........
I saw that a PSVANE tube was preferred to the stock tube in a DAC that was very popular last year.
Good luck on your quest. 8)
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In my DAC and T8 I tried quite a few NOS 6CG7's including NOS RCA Clear Tops and eventually went back to the current production EH.
Interesting........
Hello Audio Experts!
Interesting indeed! And then we have this opinion on the 6cg7 EH tubes from one of the big dogs here (Ultra Pre):
"They had no sonically redeeming qualities in my system. They were way too bright with irritating sharp harsh treble and they lacked bass. Vocals sounded less natural and the midrange sounded dead. They were also very ssssibilant."
He liked the RCA better!
Well, I've had my T8+ for about a month now, so it's time to change the tubes, right? :green: I am noticing a little sibilance with the stock EH tubes. Has anyone tried the Cryo Gold Pin EH tubes yet? Or have an opinion on cryo tubes in general?
http://www.cryoset.com/catalog/product_info.php?products_id=344&osCsid=dd8178d27d2d09e4169f89088813be8e
Decisions, decisions.... :scratch:
Murf
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Brimar Yellow "T's". Hard to find, usually priced to high, but man are they good. Detailed, smooth, they just sound right to me.
JCarney
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Hello Audio Experts!
Interesting indeed! And then we have this opinion on the 6cg7 EH tubes from one of the big dogs here (Ultra Pre):
"They had no sonically redeeming qualities in my system. They were way too bright with irritating sharp harsh treble and they lacked bass. Vocals sounded less natural and the midrange sounded dead. They were also very ssssibilant."
He liked the RCA better!
Well, I've had my T8+ for about a month now, so it's time to change the tubes, right? :green: I am noticing a little sibilance with the stock EH tubes. Has anyone tried the Cryo Gold Pin EH tubes yet? Or have an opinion on cryo tubes in general?
http://www.cryoset.com/catalog/product_info.php?products_id=344&osCsid=dd8178d27d2d09e4169f89088813be8e
Decisions, decisions.... :scratch:
Murf
I was very surprised with what happened with the EH's because until that point I ALWAYS preferred NOS to current production. I'm pretty sure you are quoting Larry who I sold a pair of the RCA clear tops to. They worked really well for him. So many variables, all AVA gear but different models and combinations, and different speakers and rooms and ears.
There are plenty of folks on AC that swear by cryo'ing. Most likely there are many AVA Circle folks that have the opposite opinion. I've never tried any. Let us know how they sound if you try them.
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Hi Marty,
"Big Dog" = "Greyhound". :lol:
Murf
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Hi Marty,
"Big Dog" = "Greyhound". :lol:
Murf
:lol: Yep, that's Larry. 8)
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I vote for Sylvania Gold Brand 6201's too. I used them in VTL monoblocks and also in my VTL 5.5 preamp. They have a very crystal clear bell-like tone to them similar to the Amperex Bugle Boy sound.
steve
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murf, see this discussion concerning 6CG7: http://www.audiocircle.com/index.php?topic=84682.0
I'm using RCA Clear Tops and like the sound. MY Avastar is a hybrid pre-amp, not and an all tube T8+. I'm not sure if rolling tubes in my hybrid will make that dramatic difference. As far as sibilance with the stock EH tubes, what is your source feeding your preamp?
steve, do you have a reliable vendor for the Sylvania Gold 6201s?
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I am currently using Raytheon and Sylvania Black plate tubes from the late 1950's in my Ultra II DAC and Ultra II Preamp. They have a warmer side with deeper bass and wider sound stage and lack the sibilance that I got from the stock EH's, RCA Clear tops, Tung Sol Grey plates. The mid range is more liquid and there is greater depth to the music with an overall better musicality. The trade off is that there is just a hint of loss of high freq detail but it is worth it.
Larry
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steve, do you have a reliable vendor for the Sylvania Gold 6201s?
Upscale Audio
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The Genalex Gold Lion cryo 12at7's beat every thing I threw at my 350 and 600R. Before that the '60s Mullard gray plates worked best in my systems. Anyone else tried the Genalex?
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Hydro,
I have an AVA 600R amp, and have order a matched pair of the Genalex Gold Lion Cryo 12AT7's. Should get them tomorrow, I will spends some time listening and let you know what they do compared to the original tubes that came with the amp.
System
DAC: AVA FET Valve Hybrid
Pre: AVA FET Valve Hybrid
Amp: AVA FET Valve Hybrid 600R
Speakers: Salk HT3's
TT: VPI Traveler
Room has a bunch of acoustic dampening
Kyle
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Hydro,
Thank you for the good recommendation. I received the Genalex Gold Lion Cryo 12AT7's (matching pair) and replace the stock tubes in my FET Valve Hybrid 600R amp. I let the system warm up about 30 minutes before I played anything. Then I started listened to digital music (FET Valve Hybrid DAC) and all I can say is WOW!!!!!!!! Compared to the stock tubes these Genalex are a GREAT improvement. There is a wider soundstage, cleaner, more colorful, more resolute, and sweeter sound that is more life like - realistic. The tonal quality is truly a magnitude better than stock. Horns, piano, drums, symbols, voices sound even more life like than before. I only have a few hours of runtime now and having a hard time turning it off, so far so good.
When I first turned the amp on was worried because these Genalex tubes don't glow and I thought something was wrong. So I double check all switches and connections and then tried some source music and the WOW began.
Frank,
If you have not heard your FET Valve Hybrid 600R with these tubes then you really should treat yourself. I can definitely recommend them for this amp.
Kyle
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Kyle, I noticed you have the same Salk speakers I have. Man do those image. The Genalex tubes are the only tubes that get the air and phasing right guitar pedal effects, have a real sound rather than a tube sound. I have to say they were a bigger upgrade for my Soundlab A-1 system than going from the ultra double 350 to the new 600R. Glad to hear someone else hears the difference I did.
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One other thing about the Genalex, I tried them in my AVA dac and they didn't sound nearly as good as Telefunken's. They were brand new then, but I find that cryo tubes don't seem to have much of a burn in time. I'll shut up now.
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Kyle and Hydro,
Thanks a lot guys for feeding my addiction! I convinced myself that spending $40+ per tube on Genalex tubes would not be worth it. Now because of you two I think I have got to try them. :lol:
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Thank you about your experiences with the Genalex Gold Lion cryo 12at7s. I think I'll pick up a pair for my 400R.
What on-line store did you purchase them?
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let us know what you think once you've tried them!
part number: Gold Lion ECC81 / 12AT7 Gold Pin Cryo Matched Pair
at the following link:
http://www.cryoset.com/catalog/product_info.php?products_id=304&osCsid=8769dcc99aee530cd2c7700172a54373
enjoy :D
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Hydro,
My AVA Dac uses 6CG7 tubes. I can't find Genalex Gold Lion tubes in this size. Did you use the cryo Electro Harmonix brand?
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Actually Dean Barnell sneaked a set of Gold Lion 12AT7 tubes into my shop Fet Valve amplifier a while back while I was out for lunch. I never noticed any difference at all.
Our ABX box does not let one get away with fooling themselves! Perhaps I simply need to cryo the ABX box. :)
Regards,
Frank Van Alstine
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Nightfall, My dac is an older AVA that uses 12at7's. As far as hearing a difference in the tubes, I find that all A/B boxes affect the sound, and there is no really good way to instantly compare two componets. It is more, close your eyes, listen to the music and see how much emotion it evolks and how interesting the sound field is. Does my mind wander to other things? or am I transfixed by the preformance. Also, time and again, I find that friends hear imaging differently. I have rolled a lot of tubes and they all sound different.
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Couple of things:
1) Let me make this unquestionably clear: On my system the Gold Lion ECC81 / 12AT7 Gold Pin Cryo Matched Pair, made a night and day difference. This a factual statement. I will not replace them back to the original tube condition. This was the only change made to my system in this trial.
DAC: AVA FET Valve Hybrid (stock tubes)
Pre: AVA FET Valve Hybrid (stock tubes)
Amp: AVA FET Valve Hybrid 600R (Gold Lion ECC81 / 12AT7 Gold Pin Cryo Matched Pair)
Speakers: Salk HT3's
Room: Very Acoustically Dampened (many acoustic panels and bass traps)
It could be that my system combination is different than others which may explain differing results. Frank, I can't imagine that your system isn't already dialed into the max with so many improvement tweaks that a normal person couldn't keep track of the improvments.
2) I have purchase a pair of EH Gold 6CG7 tubes that i will receive on Monday and will try them in my FET Valve Hybrid Preamp. I will report back on the results. Below is the link to the specific 6CG7 tube pair that I have coming.
http://www.cryoset.com/catalog/advanced_search_result.php?keywords=EH+Gold+6CG7+&search_in_description=1&osCsid=96646e8182ef8a9d8c24ee40e2a0fb40&x=6&y=10
I Love my 2 channel system
Kyle
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Couple of things:
1) Let me make this unquestionably clear: On my system the Gold Lion ECC81 / 12AT7 Gold Pin Cryo Matched Pair, made a night and day difference. This a factual statement. I will not replace them back to the original tube condition. This was the only change made to my system in this trial.
DAC: AVA FET Valve Hybrid (stock tubes)
Pre: AVA FET Valve Hybrid (stock tubes)
Amp: AVA FET Valve Hybrid 600R (Gold Lion ECC81 / 12AT7 Gold Pin Cryo Matched Pair)
Speakers: Salk HT3's
Room: Very Acustically dampend (many acustic panels and bass traps)
It could be that my system combination is different than others which may explain differing results. Frank, I can't imagine that your system isn't already dialed into the max with so many improvement tweaks that a normal person couldn't keep track of the improvments.
2) I have purchase a pair of EH Gold 6CG7 tubes that i will receive on Monday and will try them in my FET Valve Hybrid Preamp. I will report back on the results. Below is the link to the specific 6CG7 tube pair that I have coming.
http://www.cryoset.com/catalog/advanced_search_result.php?keywords=EH+Gold+6CG7+&search_in_description=1&osCsid=96646e8182ef8a9d8c24ee40e2a0fb40&x=6&y=10
I Love my 2 channel system
Kyle
Hey Kyle, looking forward to your impressions. I have the last generation AVA gear with the HT3's and am running the stock EH tubes. 8)
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Martyo,
Will do, might be late monday or tuesday before I have any experiences to share.
Kyle
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Kwebb, I just got the Gold Lion cryo ECC81s and have been listening to them tonight in my 400R. Right out of the box they sound fantastic. I think they blow away the Telefunkens. All of your comments hold true to my system as well (Avastar Preamp and Zu Audio Soul Superflys). I really can hear an improvement no matter what type of music. They are keepers. By the way, the FET Valves are great with rock and electronic music!
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Trackball02,
Yes, they are a good set of tubes! I am very glad that you are enjoying them as well. Its like all my whole collection of music is all new again and I am listening to it all again for the first time.
Kyle :D
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Glad you guys are enjoying the Gold Lions. The really good thing about them is that they are in current production and you know you are getting a fresh set of matched tubes and can have some spares. I have been running mine for a couple of years in three FetValve amps and they still sound fantastic. I use an AVA Super Pas with Telefunken's as a preamp on my Soundlab system and the combination is magic. Audio Note preamp with 60' SQ Amperex tubes in my Salk HT-3 studio system, incredible. So many stereo's, so little time.....
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Martyo,
Just a quick follow up on the Electro-Harmonix 6CG7 match cryo pair tube set. I received the tubes yesterday and put them in my FET VALVE Hybrid preamp. They replaced the factory install non-cryo-ed Electro-Harmonix counter part. The difference in sound was slight but noticable. I was able to distiquish a little bit better clarity in details such as brush cymbals and original recording studio echos. The difference was an improvement but not earth shaking in magnitude.
I have ordered a matched balance pair of RCA Clear Top 6CG7's (non-cryo-ed) that i will try in this same preamp. If they provide are a significant improvement then will leave the Clear Tops in the preamp and move the Electro-Harmonix 6CG7 match cryo pair tube set to my FET VALVE Hybrid DAC and see how that works.
Tube rolling is fun!
Kyle
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Martyo,
Just a quick follow up on the Electro-Harmonix 6CG7 match cryo pair tube set. I received the tubes yesterday and put them in my FET VALVE Hybrid preamp. They replaced the factory install non-cryo-ed Electro-Harmonix counter part. The difference in sound was slight but noticable. I was able to distiquish a little bit better clarity in details such as brush cymbals and original recording studio echos. The difference was an improvement but not earth shaking in magnitude.
I have ordered a matched balance pair of RCA Clear Top 6CG7's (non-cryo-ed) that i will try in this same preamp. If they provide are a significant improvement then will leave the Clear Tops in the preamp and move the Electro-Harmonix 6CG7 match cryo pair tube set to my FET VALVE Hybrid DAC and see how that works.
Tube rolling is fun!
Kyle
Thanks Kyle. I may have to check out a pair. Inexpensive improvement is always good. 8)
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Kyle, Hydro and all other members,
I received my Cryo Gold Lion 12AT7 tubes today. I replaced the stock JJ tubes in my AVA 400R. I did an A/B comparison using Led Zeppelin's "Stairway to Heaven" from my CD of IV. I WANTED there to be no difference. Then I could forget about spending any more money upgrading tubes in my other AVA components. OMG! The GL blew away the JJs. It was not even close. The GLs gave the music a whole new level of REAL! Everything sounded better! EVERYTHING! I had to turn the volume down three times! It is something that one must experience to believe. Now I will be buying more to try in my preamp and dac. I had no interest in "tube rolling" at all before this and I do not care about "voodoo" audio tweaks. This upgrade is for real.
Thank you both for helping me make my system that much better!
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Nightfall,
Tube rolling is a good thing. The Cryo Gold Lion 12AT7 tubes are the real deal and there is no way would i pull them out of their sockets. Hydro turned me onto them. Here is what else i have done:
1) Replace the stock tubes in my FET Valve Preamp with the Gold Electro-Harmonix 6CG7 match cryo pair tube set. This produce a slight but noticeable improvement (5% to 10% sweater).
2) Replace the stock tubes in my FET Valve DAC with RCA Clear Top 6CG7 NOS (new old stock). This is a bigger improvement over the stock Electro-Harmonix 6CG7 (15% to 20% improvement). Better, deeper, clearer base, better over all resolution and liquidity.
I am really happy with these changes and i am glad to be able to share with all.
Kyle
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Glad others are hearing the same thing I did. Don't forget tube dampers, another cheap tweek. Not on the same scale as tube rolling but worth the few $ they cost. I have found the Red Silicone o-rings are about as good as any. Put them where the mica supports touch the glass. Good listening everyone.
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Kyle, I'm pretty much running the same combination as you: Cryo Gold Lion 12AT7 in my 400R and RCA Clear Tops NOS in my Avastar. Great combination and I also do not see any reason to change the tubes. I am also re-visiting my music collection. 8)
If you get bored, buy an Ultravalve, like I did, for more tube rolling fun!
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Trackball02,
Thank you for you inputs. This is a great hobby. I was kind of itching for a T8 preamp just to hear how different it is. Was also thinking of getting the source switching box and a Humdinger to polish things off. My problem is my wife, who is already on to my addiction, is making me slow down. So i will take the steady easy goes it path and spread out the purchase of new toys over a longer period of time.
Kyle
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Kyle, Hydro and all other members,
Update: I received my cryo treated tubes today for my AVA Fet Valve Preamp (Gold Lion 12AT7s) and AVA Fet Valve Dac (EH 6CG7 gold pin). There was an improvement over the stock tubes but not as much a difference as upgrading the AVA Fet Valve 400R tubes. I think they sound clearer, quieter and more detailed. Not night and day but maybe a 10% improvement (hard to describe). There was the least change with the DAC. Very glad that I tried them. I hear things that I never noticed before. I think my system sounds better than it ever has. Anyone willing to try out the cryo treated interconnect? It makes me wonder.
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Nightfall, Have you tried Telefunken 12AT7's in your preamp? They really make my AVA modded Dynaco Super Pas sing. You can have them cryo'd for 10$ each. If you would like to try some before buying, I have an spare pair you could try. Just pay shipping both ways.
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Nightfall, just remembered my spare pair of Telefunkens are 12ax7's. I have quite a few different 12at7's though. The Siemens 801S's are best in my AVA Ultra DAC and Sylvania tripple mica's work well in recording preamps.
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Hydro,
thank you so much for the offer to try other tubes but I am not really interested in further "tube rolling". I only tried it this time because you guys said it made an improvement. I really don't like removing my covers for fear that I will strip the screws or screw something up inside. I think this was definitely a worthwile upgrade, but I like to leave my stuff alone and not tweak things too often. The next thing I might give a try ($ permitting) would be a Magnepan DWM. Thank you and Kyle for helping make my system sound better than it ever has. I got goosebumps listening to RUSH "Vital Signs" last night! I can believe how 3 dimensional it sounded!
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Hydro,
thank you so much for the offer to try other tubes but I am not really interested in further "tube rolling". I only tried it this time because you guys said it made an improvement. I really don't like removing my covers for fear that I will strip the screws or screw something up inside. I think this was definitely a worthwile upgrade, but I like to leave my stuff alone and not tweak things too often. The next thing I might give a try ($ permitting) would be a Magnepan DWM. Thank you and Kyle for helping make my system sound better than it ever has. I got goosebumps listening to RUSH "Vital Signs" last night! I can believe how 3 dimensional it sounded!
Hey. So you would run the bass panels with your 1.7's? That should be fun. :eyebrows:
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I have a 600R and Fet Valve DAC coming next week. I went ahead and ordered a pair of the Gold Lions for the amp. Is the consensus the stock tubes are best for the DAC?
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I know this is a very old thread, but I wanted to post my experiences regarding tube rolling.
I picked up a 350EXR off usaudiomart that came with Sylvania 12AT7WA tubes with green lettering. They are very dynamic and musical with good highs and lows, and a very nice midrange that presents the soundstage a bit more forward than I'm used to. For all previous tube gear I had been running the re-issue Genalex Gold Lion tubes. Gear that I have used the Genalex tubes with are Decware CSP2+, TAD 150 Signature and Doge 8. Since I had a spare set of Genalex I installed them into the 350EXR thinking they would better the Sylvania 12AT7WA. I think the Genalex 12AT7's that I installed into the 350EXR must be bad because the soundstage shrank and moved back a bit behind the speakers. Additionally, the bass was really lightweight compared to what I'm used to with the Genalex. The decrease in bass was as if the speakers were hooked up out of phase. Double-checking the speaker cables confirmed they were wired properly.
I'm considering ordering another pair of Genalex Gold Lion 12AT7 to see if the spare tubes have simply gone bad. Overall I'm really happy with the amp, though the heatsink fins on the back of the unit do get extremely warm. I'd estimate they're over 130° F.
Equipment = NAD M51 --> Doge 8 (4x Genalex 12AT7) --> 350EXR (2x Sylvania 12AT7WA) --> PMC OB1
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If the heat fins are getting too warm in normal use at idle, then the bias adjustment is set too high.
This can be just a case that the tubes in use are far different than the JJ ECC81/12AT7 we supply, or possibly someone has messed with the setting.
Bias current is measured with an ammeter replacing the internal V+ fuse for the channel under test. It should be about 100 mA. It is difficult and can be hazardous to attempt to measure or adjust bias yourself. You might want to have us do it if a new set of tubes don’t help.
Call us at 651-330-9871 for more help.
Frank
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Mullard gold pin 6201 is the best 12AT7 I've ever tried.Just saying
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Frank - Thanks for the feedback. I do have a multimeter that can be used as an ammeter so I can perform the biasing myself. I'll give you a call later this week. I'm going to install another pair of Genalex 12AT7 that I know are good (they were purchased from Cryoset last year) and see if those work better than the pair that sounded off.
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See if you can find an audio circuit board part number so I can dig it out of archives here to better advise you of the tricky and dangerous bias set task. Be very careful of the big vertical board in front of the audio boards. There is 330V dc on the black heat fins.
The board will be labeled PC-xxxx. Something
Frank
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The serial number of the 350EXR is 062804a if that helps. Regarding the shock warning, I read through various threads and read the documentation that was provided with the amp so I'm well aware of the dangers of working inside the chassis and will be picking up a pair of thick rubber gloves from the store to prevent contact with the heatsinks.
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Assuming that your amp has our PC-704 single sided audio circuit boards, the bias adjust trim pot is located near the bottom of the circuit board, straight down from the tube socket.
Small tweets of the pot make obvious bias current changes. Don't over adjust.
Frank
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Thank you Frank. A pair of fresh Genalex 12AT7 are on the way from Cryoset and I'll report back after testing.
Regarding the sound of the amp, it easily betters every single amp I've ever owned. I will definitely recommend your gear to others. If I had the budget I would spring for a 400r, but I am more than satisfied at the moment. It's been a long, long time since music has been this enjoyable to listen to. Thank you thank you thank you.
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After installing a fresh new set of Genalex 12AT7 from Cryoset into the 350EXR.........the sound returned to what I was expecting. Compared to the Sylvania 12ATWA (green lettering), the Genalex are less lush and more solid state sounding, which is exactly how they should sound.
The bias pots are directly below the tube sockets as you had suggested Frank, and I'd hate to have to adjust the bias on the left channel because there's not much room to work on that side.
Thanks again.
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The trick to access bias pot is to remove the 5 screws attaching back panel to main chassis on the bottom of chassis so you can tip back panel back.
Did new tubes deal with excess heat issue?
Frank
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Changing the tubes out did not have any effect on the temperature of the heatsinks. It is still extremely warm to the touch. I can only keep my fingers on the heatsink for 5 seconds or so.
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I have a 350, 400and 600, the 350 runs much hotter than the new generation amps.
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The amps from the EXR series on have regulated output transistor power supplies.
In them, the bias current is adjusted from the regulated power supplies, not from the higher raw supplies. Thus they produce less heat at the same bias current settings and run cooler.
Frank
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The amps from the EXR series on have regulated output transistor power supplies.
In them, the bias current is adjusted from the regulated power supplies, not from the higher raw supplies. Thus they produce less heat at the same bias current settings and run cooler.
Your amplifier should not be running that hot. The bias setting is probably way too high.
Frank
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Following up on my earlier report...
It turns out the pair of Genalex Gold Lion 12AT7 that were purchased from Cryoset were no good. I've purchased a few sets from them and this pair just did not sound right even when tested in my Doge 8 preamp. They sounded very thin and were lacking in the low end. They've since been swapped out for a pair of NOS Sylvania JHS 12AT7 black triple mica and the sound is fantastic. In my experience, tube rolling changes are very apparent and dramatic. So far I've tested with the following:
Genalex Gold Lion 12AT7 (cryo)
Genalex Gold Lion 12AT7 (non-cryo) - Sounded like what you would expect from the Gold Lion series. Well balanced across the frequency spectrum. More hi-fi sounding than tube when compared to NOS tubes.
Sylvania 12ATWA (green label) - Very warm and lush midrange. Rolled off pretty severely on the high end giving a darker tone (this may be due to the tubes age as the previous owner did not specify how many hours were on these).
Sylvania JHS 12AT7 (green label) - These are supposedly similar to the Sylvania Gold Brand 6201 gold pin. I'd say they're about a 95% match for the sound of the 6201's. The Gold Brand 6201 are regarded as some of the best 12AT7's and these are no exception. Very good extension top to bottom, with a pronounced midrange that makes for great imaging and a wide soundstage. These and the 6201 are my favorite.
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Any 12AT7 with a rich warmish tone. RCA, Mullard, Amperex in that order.
charles