Eight, count them, eight beautiful NOS Mullard EL34 tubes

Discussion in 'Audio Hardware' started by ggergm, Jul 20, 2017.

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  1. ggergm

    ggergm another spring another baseball season Thread Starter

    Location:
    Minnesota
    I've been working on a deal with @indy mike for tubes for my Primaluna Dialogue Premium HP integrated amp. I've been quite pleased with the KT150 tubes I've been using, enjoying the extra power and the improved bass and high end over the stock EL34 tubes. But still, I had to know. What would NOS tubes sound like?

    I will soon find out. It took a while but indy mike found eight Mullard made NOS XF2 single halo getter tubes in terrific shape. They are now mine.

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    The date codes say the Amperex tubes were made in May 1973, near the end of the XF2 run. The Philips tubes are not as well marked but the date code on one plus the fact they have brown bases with a single getter mean they are from 1969.

    All eight tubes look great but the Amperex tubes are expecially amazing. The boxes are extra crisp, the writing on the tubes is strong and there are no indications on their pins that they have ever been in an amp. If ever 44 year old tubes are really New Old Stock, these are them. The Philips aren't as pristine but the boxes are strong with the seal still on the top and the proper tissue paper and cardboard around the tubes. They all checked out well with Mike's tester.

    So I plugged them in my PrimaLuna, let them warm up a bit, and then cued up a LP. And the tubes sounded...

    ...terrible. The music was thin and edgy. They sounded exactly like tubes which need to be broken in. More than ever I'm convinced the Amperex tubes actually are new. Those getters also may have a big job that will take a while to accomplish, restoring the vacuum within the tubes. There has to be some leakage over the decades. I think I'll leave the amp on for a couple of days.

    I'll let you know how things develop but I'm expecting to be in hog heaven soon, maybe even by tonight. It's been my experience as tubes burn in, it's not that their sound changes as much as they get to their best sound sooner. Fully burned in tubes can sound their best after being switched on for just an hour. New tubes take hours to get there. As they break in, the wait for them to sound great takes less and less.

    I have patience. It's only been 44 years.
     
    Last edited: Jul 20, 2017
  2. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    Congrats. I recently bought a quad of Mullard XF2 brown base double-getters from my dude EUROKLANG on ebay, and they're head and shoulders above any other EL34 I've used.
     
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  3. chervokas

    chervokas Senior Member

    Strange. "Thin and edgy" are the opposite of how those tubes should sound. I used only old XF1 and XF2's for years until my supply just got too weak, noisy or unmatchable and the cost of acquiring new ones or good used pulls got well beyond my means. I've never heard another EL34 like 'em. The legendary palpable midrange presence and almost tactile timbres they deliver coupled with an amazing upper frequency ease, are just one of a kind. Not the ultimate in frequency extension at either extreme. But the magic is real.

    Thin and edgy -- I've heard that from New Sensor Electro Harmonix EL34s, but not Blackburn Mullards.

    Personally I'm not a big believer in tube burn in -- after a couple of hours of run-in at voltage to weed out early failures, a tube should only need to come up to bias and thermal stability when to turn it on to sound it's best and it's only going to get weaker and worse and noisier over time.
     
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  4. SandAndGlass

    SandAndGlass Twilight Forum Resident

    I have an EL34 amp, a Decware Torii Jr. It is running four modern day Tung Sol and it sounds really nice and clean, no harshness at all. All of the tube was magic, but there was no extra magical midrange.

    The amp really took me back, as I hadn't expected this good of sound, coming from modern EL34's.

    I have a couple of quads of "UK" type of new EL84's that are supposed to sound like the old Mullard EL34's. I put them in the Rogue M-150 monoblocks for a while. Did they sound nice? I guess they did. Was there nice midrange? I would say yes. Was the midrange "magic", not really.

    While they hint at being like NOS Mullard's, made in the United Kingdom, way back when, they are not.

    I know that EL34's don't have the bass of a KT88, I figured that would not be a problem, since I have a good size commercial subwoofer next to the A7's. The EL34's had nice sounding bass, but not DEEP base. I had the sub going all the time, no problem.

    When I decided to switch back to the KT88's, I could not believe the difference! The bass was huge! Since the subs are set up to be a sub, they don't walk all over the regular bass. With the KT88's back in, the normal bass was much stronger, in a good way.

    One way to place emphasis on the midrange, is to cut the bass. FWIW

    The base on the EL34 based Decware is excellent, as is the bass on the original Mullard's. Little different sound, old vs. new, but both are still nice.

    I do have a small PrimaLuna KT88 based amp. I can use other tubes in it. One day I will try a swap of the UK-EL34's to see how they sound in that amp. The Rogue amps are a bit too powerful for EL34's.

    I have a couple of Quads of PrimaLuna's EL34's, that I bought to try in the Prologue Five.
     
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  5. Strat-Mangler

    Strat-Mangler Personal Survival Daily Record-Breaker

    Location:
    Toronto
    As somebody who's dealt with tubes in guitar amps for a long while, I don't believe at all in tube burn-in. Complete and utter myth, IMHO.

    Hope you end up liking the combination but I'd get myself a tube tester to look into which tube(s) is/are causing the problem.
     
    ggergm likes this.
  6. ggergm

    ggergm another spring another baseball season Thread Starter

    Location:
    Minnesota
    In the past I have found tube burn-in to be real so I'm holding the course. The amp sounds better this afternoon than it did this morning. Frankly, what do I have to lose by leaving the amp on for a few days and hearing what happens?

    I wonder if I'm onto something, saying the getters have a lot of work to do. First, over 44 years, a certain amount of the atmosphere has to leak into the tubes. Nature abhors a vacuum, right? Second, I may have found evidence to that effect. These tubes have less gain than the factory EL34 tubes. If there is gas in the tube, that should reduce their efficiency. Electrons traveling from the cathode to the plate are absorbed by gas particles along the way and the tube doesn't work as well. It would explain the lower gain. It isn't a lot, and it's equal in both channels, so it doesn't seem to be a bad tube. Plus these were just benched by @indy mike and checked out fine.

    I appreciate your comments. Let's have a healthy discussion. But for now I think I'm going to do what I believe is best and that's leave well enough alone. I'm going to run my amp. Atomic batteries to power. Turbines to speed.
     
    Last edited: Jul 20, 2017
  7. MichaelXX2

    MichaelXX2 Dictator perpetuo

    Location:
    United States
    You might find that, for whatever reason, XF2 Mullards don't do a good job in your particular circuit. I have to admit though, I'm super jealous! I was eyeing an octet of Mullards for my Jolida 1000p, but I settled on the RFT Siemens EL34 tubes for half the price. I have found that letting a NOS tube burn in will have an appreciable effect. Don't delude yourself if it doesn't work out, however. I'm sure you can get your money back, and then some for those beauties...

    :love:
     
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  8. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    I'll tell you, I don't think preamp tubes burn in, and can't think of any reason why a tube would need to burn in beyond the "make sure it isn't faulty" stage, but when I tried out JJ KT77s, for the first hour or so it sounded like a vintage amp with bad caps, that sort of ultra-romantic distorted sound that some people associate with tubes but those in the know would call "broken". They definitely didn't sound like that after an hour or so, and the sound evolved in that period. Note I'd had them on for 30 minutes before I biased them and put on music. I've never had this experience with any other tube, however.
     
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  9. Strat-Mangler

    Strat-Mangler Personal Survival Daily Record-Breaker

    Location:
    Toronto
    Don't think you'd need to waste dozens of hours of their lifetime to see whether the tone changes but it's up to you to do so.

    Things can happen during shipping. All it might take is for one tube to be defective for everything to sound terrible.
     
  10. indy mike

    indy mike Forum Pest

    The tubes were all checked on my Jim McShane calibrated B&K 747B tester for life/shorts/grid emissions; the B&K tester doesn't run EL34s at 400 volts on the plates like an amplifier would, so they were then all checked on my Maximatcher II tester running the tubes at 400 volts on the plates and -36 volts bias per the Maximatcher EL34 settings with about a 15 minute warm-up per tube. The tubes were then matched to approximately 5% or better per pair, and all were run in my pair of Dynakit MK IV amps for listening at high volumes. The bias was initially set and then checked after 30 minutes running time - the bias held steady, and then several extended listening sessions per pair with the volume cranked were performed to make sure the tubes weren't noisy. Dynas run tubes fairly hard, and those Mullards were made to be run to spec - it was a treat to have tubes Dyna regularly used in their amplifiers. It is possible something may have happened during shipping, but I'm very careful to make sure the possibility for damage during shipping is minimized.
     
    Last edited: Jul 20, 2017
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  11. Strat-Mangler

    Strat-Mangler Personal Survival Daily Record-Breaker

    Location:
    Toronto
    Nobody was accusing you of anything. Like I insinuated with my last sentence, there's a possibility the combination isn't appealing to the OP in which case, that is nobody's fault. Or that something occurred during shipping.

    Hopefully, the OP will be happy in the end. If he doesn't like the sound, he could easily sell them on eBay or on guitar msg boards like TGP for the same amount he paid for. These are heavily coveted for Marshalls.
     
  12. ggergm

    ggergm another spring another baseball season Thread Starter

    Location:
    Minnesota
    Yes, I do. It's how I saved $1,100 on this PrimaLuna amp when I bought it.

    Last fall I heard about a troubled amp. It was owned by a man who had used it for 50 hours and hated it. He liked his old solid state amp better, a really great Pass Labs piece. Because of his family situation, his listening sessions were short, only a couple of hours long, and I wondered if the tubes were truly broken in. He sold it to me for $3,300, when retail is $4,400 and generally commands it. The PrimaLuna Dialogue Premium HP Integrated has been Class A Recommended Component from Stereophile for a couple of years. It's hot right now.

    When I got it home I plugged the PrimaLuna in and after a couple of hours of warm-up, was beginning to think the previous owner was smarter than me. My Plinius 9200 solid state amp, also highly regarded, especially when it came out 15 years ago, sounded better than this tube amp. I sent a note to the previous owner saying maybe the PrimaLuna amp had a real problem. But before giving up on the amp, I kept it turned on. After 18 hours of being on, it started to come into its own. By the next day it sounded better than my Plinius. I contacted the previous owner again to ask him if he'd ever kept the amp turned on for a day. He said, no. I continued running the amp hard. A week or two later, I was totally in love with the PrimaLuna and understood why it was rated Class A. Since then my Plinius has stayed, unloved, on a shelf in my basement.

    I went through a similar learning curve, although not as dramatic, when I changed out the stock EL34 tubes for KT150s. When I installed the KT150s, the amp's sound definitely took a hit and took a few days for it to sound really good again.

    Strat-Mangler, I understand you don't believe in tube break-in. I do. I have experienced it. It has saved me money. I'm not wasting my time here. I am convinced I am instead making the tubes sound their best.
     
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  13. indy mike

    indy mike Forum Pest

    I just wanted folks to know that I do have test gear and make sure that tubes I obtain are tested, and whenever possible used in gear to see how they work in real life situations. I'm puzzled about the initial impression the tubes made - in my Dyna amps they sound great. There are so many variables involved when running tubes, especially in an amp that can run a wide variety of them. While I can run either EL34s or 6L6GCs in my Dynakit MK IV, the Prima Luna can use tubes that would cause the transformers in my Dyna MK IVs to die a pretty quick and ugly death. I don't know what those KT-150s sound like, and unless I find someone with an amp that can run them properly I won't have a clue how they fare when compared to EL34s.
     
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  14. Strat-Mangler

    Strat-Mangler Personal Survival Daily Record-Breaker

    Location:
    Toronto
    Your 200 feedback rating at 100% satisfaction should be indicative enough to the fact that you stand by what you sell. Don't believe anybody would ever think otherwise. :)
     
  15. Strat-Mangler

    Strat-Mangler Personal Survival Daily Record-Breaker

    Location:
    Toronto
    You could be right or you could simply have adapted to the sound signature of the PrimaLuna over time. It'd be interesting to have you do an objective comparison between the two, now.

    Equipment burn-in is one of those processes which require some faith. Some believe in it while others don't.

    Either way, I sincerely wish you the best. Either a tube is defective or you're not a Mullard guy. If the tubes are fine but not your cup of tea, what's Plan B? Another brand or putting back the tubes you had before?
     
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  16. indy mike

    indy mike Forum Pest

    I enjoy the hunt for tubes and do my best to make sure they work properly - if a tube doesn't work the way it should I do what I can to take care of the problem. :cheers:
     
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  17. ggergm

    ggergm another spring another baseball season Thread Starter

    Location:
    Minnesota
    Thank you, as I wish you. This is a discussion forum. This kind of conversation keeps this place alive. I'm glad we are having it. :)
    I'll put the KT150s back in the amp. They sounded great.

    Actually, I'm hoping to switch back and forth between the two sets of tubes, depending on the season. These tubes run significantly cooler than the KT150s. Maybe the Mullards will be my spring/summer tubes. In the fall and winter, I'll let the KT150s help keep my house warm.
     
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  18. indy mike

    indy mike Forum Pest

    RFT made EL34s are unfortunately starting to creep up in price; they are a fine choice if Mullards aren't in the budget (that would be me most of the time, although I have started to salt away some NOS EL34s for occasional test drives). :cool:
     
  19. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    I wonder if all the fancy auto-bias technology in the Primaluna amps impacts the sound signature one gets from the tubes?
     
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  20. ggergm

    ggergm another spring another baseball season Thread Starter

    Location:
    Minnesota
    I've wondered about that, too. Their Adaptive AutoBias circuitry is dynamic in its operation, looking at each tube individually and adjusting the amp to make that tube perform its best.

    Link: PrimaLuna Dialogue Premium HP Integrated Amp webpage

    As the tube is used, it will change, as will its bias needs. Just the tube getting hotter alone will change its electrical response and force the Adaptive AutoBias circuit to adjust.

    I speculated upthread over the getters having tough work to do at this moment. If my theory is correct, the tubes running cooler and less efficiently right now could cause the poor sound all by itself, thanks to the Adaptive AutoBias circuit. Let the amp get really hot - we know how tube amps like to run hot - and it might sound golden just because of that.

    Ah, shucks. This means I have to leave the amp on and listen to it over the course of a few days. Being an audiophile is a tough job! :nyah:
     
    Last edited: Jul 20, 2017
  21. Strat-Mangler

    Strat-Mangler Personal Survival Daily Record-Breaker

    Location:
    Toronto
    No way to override that?

    I know in guitar amps, running tubes hotter usually yields better results.
     
  22. Pinknik

    Pinknik Senior Member

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  23. ggergm

    ggergm another spring another baseball season Thread Starter

    Location:
    Minnesota
    Nope.
     
  24. chervokas

    chervokas Senior Member

    Personally I would never intentionally leave a tube amp on unattended. I've see tubes just decide to draw too much current, or resistors fail or wall voltages spike and in some of those scenarios the best case scenario is a fuse blows before a transformer is taken out, in the worst case, fire.
     
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  25. ggergm

    ggergm another spring another baseball season Thread Starter

    Location:
    Minnesota
    In general we are in agreement, chervokas. In the late '80s I tried to get a pair of Futtermans, one of the original OTL amps, to work. Instead, they'd decide to blow up simply because the day happened to end in a "y." I would never have left them turned on and alone even in a concrete bunker.

    PrimaLuna is different. There is individual protection on each output tube. I know as I've activated it when my tone arm has accidentally jumped across the record at high volumes. Making a super reliable amp, using appropriate modern electronic circuits, is one of PrimaLuna's hallmarks. Solid state reliability with tube sound is a stated design goal. I'll rely on the amp's protection to save me from a bad tube.

    I listened to a couple of record sides this morning. The amp still doesn't sound great but it no longer sounds bad. Things are moving in the right direction. I've turned the amp off and unplugged it from the wall for an hour. Normally I wouldn't cycle a tube amp this way but I want to reset its fancy-dancy electronics, including the Adaptive AutoBias circuit. I plan to keep this 23 hours on/1 hour off schedule for another few days. As things improve, and I'm sure they will, folks here will be the first to know.
     
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