12au7 Tubes

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scubalab
scubalab Posts: 3,101
in Wanted (WTB) Classifieds
Full disclosure here - I’m fairly inexperienced when it comes to tubes!

I have a Triode TRV-88ser integrated that I purchased from Skip about a year or so ago. Unfortunately it hasn’t seen much use in the time I’ve had it. A few months ago, I switched speakers back and forth comparing two different pairs and noticed that the sound was muddy in one speaker. I did the usual - reconnect cables, swap L/R speakers, etc., and could not resolve. So, I reached out to Skip and he said it’s likely a bad tube or two. I finally got around to trying some of his suggestions. At first the music sounded pretty good, but as things warmed up, I definitely noticed the sound was more pronounced from the right speaker. The first thing I did was switch the preamp tubes and sure enough, the problem followed the tubes - now the left speaker is louder.

This amp has the original stock tubes. So, I’d like to upgrade while addressing the issue. Looking for a recommendation on a matched pair of 12au7 tubes. I could also use a single 12ax7 for the input. Eventually, I’ll be looking to upgrade the Quad set of KT88 tubes, but can’t swing that right now.

I know there are some tubes in the FM. Any other options? Anyone have some good tubes they’re willing to part with that you think would be a good choice to try? Or, I’m open to recommendations on what to look for.

Thanks - Al
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  • Clipdat
    Clipdat Posts: 12,599
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    New production Tung Sol a safe bet.
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  • audioluvr
    audioluvr Posts: 5,432
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    I have a few good sets I'm not using.
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)

    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
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  • mhardy6647
    mhardy6647 Posts: 33,030
    edited October 2020
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    The nice thing about 12AU7s is that there are still reasonably priced vintage Amurrican variants on the open market. There are, of course, boutique variants, too, but there are good old meat and potatoes tubes that won't break the bank. :)

    http://www.audiotubes.com/12au7.htm
    https://www.tubesandmore.com/search/node/12au7 (some NOS variants down at the bottom of the page)
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  • pitdogg2
    pitdogg2 Posts: 24,559
    edited October 2020
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    The tall bottle 6085's are worth looking into Al. They are not cheap but they are rated at 10,000 hours. They are either made in Holland (amperex) or Hungary (tungsram). Only two plants made them so no matter the name on the side 6085 gold pins Holland, regular pins Hungary
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  • scubalab
    scubalab Posts: 3,101
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    Thanks for all the advice thus far! I'll do a little research and post back with any questions.

    @audioluvr shoot me a PM with what you have!

    Ivan @pitdogg2 , other than long life, do the 6085's generally increase the gain of a 12au7?
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  • mhardy6647
    mhardy6647 Posts: 33,030
    edited October 2020
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    scubalab wrote: »
    Thanks for all the advice thus far! I'll do a little research and post back with any questions.

    @audioluvr shoot me a PM with what you have!

    Ivan @pitdogg2 , other than long life, do the 6085's generally increase the gain of a 12au7?

    I'm not @pitdogg2, but I play him on television in some of @Hermitism's mashups B)

    I was gonna say "no, the gain's the same"... but I looked 'em up @ TDSL
    http://tdsl.duncanamps.com/tubesearch.php

    6085 has an amplification factor (each triode) of 30 per
    https://frank.pocnet.net/sheets/201/6/6085.pdf

    12AU7A has amplification factors of 19.5 and 17 (triode 1 and triode 2, respectively) per http://www.tubebooks.org/tubedata/HB-3/Receiving_Tubes_Part_2/12AU7-A.PDF

    So... yeah, a wee bit, apparently. :|

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  • pitdogg2
    pitdogg2 Posts: 24,559
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    here you go AL I find them to be very 3d'ish

    Since this tube has a much higher Gm and Mu factor than a 12AU7, the gain is going to be greater and this tube will give a more forward presentation. Awesome in phase splitter applications. If in doubt, check with your amp or preamp manufacturer to see if this tube will work OK in your application. This tube is also about twice as tall as a 12AU7, so installation space in your chassis is a consideration as well.


    https://www.effectrode.com/knowledge-base/the-12au7-tube/
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  • scubalab
    scubalab Posts: 3,101
    edited October 2020
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    Mark - as always, thanks for the comprehensive (educational) advice!

    Drew - I looked a bit into the Tung Sol's. Any particular ones you'd recommend for best bang for the buck?

    Rob - Let me know what you've got (or are willing to let go)!

    Ivan - The 6085's sound interesting. Height shouldn't be an issue as I keep the 'cage' off the amp; plus with the size of the KT88 tubes, I'd think clearance will be maintained even if I do put the cage back on. Do I really need to "check with your amp or preamp manufacturer"? I know that came from the article and not necessarily you. I don't think Triode Corporation is very responsive... It's a cool amp, but literature and support is slim to none.

    Here's a little more detail on my setup:
    • Integrated - Triode Corporation TRV-88ser. I think it's rated at 45 WPC which makes sense with the KT88 tubes. (purchased from Skip.)
    • Turntable - Fluance RT85 with the Ortofon Blue cart (purchased new from Fluance).
    • Phono pre - Lounge LCR MkIII (purchased from Zach @stangman67).
    • Speakers (Primary) - Polk Monitor 11 (RTA-11) (purchased from Jesse @F1nut)
    • Speakers (Secondary) - Polk LSiM703 (purchased new from Adorama)
    • Power Center - Monster HTS-2600 (karma from Joe @joecoulson :) )
    • Speaker Cables - Zu Audio Libtec (purchased new from Zu)
    • ICs - Wireworld Oasis and BJC LC1 (purchased from Zach @stangman67).
    Forgot to mention the "karma" rack from Zach @stangman67 for being a 'repeat' customer of his B)

    Photos:

    r8mguacoa6x1.jpeg
    d6g0ux9g6gz3.jpeg
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  • pitdogg2
    pitdogg2 Posts: 24,559
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    I didn't check, I also tried 12at7's in the AU spot I knew right away they would not work. I do not get the SHHHHH with the 6085's like I got with the AT's. The 6085's are dead quite in my pre-amp.
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  • Clipdat
    Clipdat Posts: 12,599
    edited October 2020
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    scubalab wrote: »
    Drew - I looked a bit into the Tung Sol's. Any particular ones you'd recommend for best bang for the buck?

    https://www.thetubestore.com/tung-sol-12au7w-6189?quantity=1&additional_options=3

    This is what I was thinking. I realize it won't have the performance of the nicer NOS options, but it could be a quick and easy way to get back up and running with a minimal expenditure.
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  • audioluvr
    audioluvr Posts: 5,432
    edited October 2020
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    These are what I'm using in my pre. I've bought 3 matched pairs because I like them so much and surprisingly they all sound the same.
    https://www.ebay.com/itm/163533485479
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)

    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
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  • scubalab
    scubalab Posts: 3,101
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    Thanks to everyone who reached out in this thread and via PM. Very early on, Bruce (@Faustin) reached out to me with some suggestions including the Raytheon (made for Baldwin) tubes. I decided to give them a try. I got them today and had a couple minutes at lunch to try them out. I’m thrilled to say I’m back in business!

    I’m not one who can hear the improvements some things (like cables) can bring, but these tubes... WOW! I’ve now got a soundstage that expands not only from speaker TO speaker, but beyond them (left, right, front, and back). I also immediately noticed fuller bass, more balanced, warmer mids, and pleasant highs. Next to adding a separate amp on my home theater, these tubes (over the stock tubes) have been the most impressive audio improvement I’ve experienced.

    Both sets of speakers (the Monitor 11s and the LSiM703s) sound incredible. Maybe the 703s are finally breaking in, but these little speakers present way bigger than they are!

    Thank you Bruce for reaching out and for the great tubes.

    Rob, I’m still considering giving the RCA clear tops you have a try as well. I’ll keep you posted.

    Thanks again everyone
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  • Clipdat
    Clipdat Posts: 12,599
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    Very nice.
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  • Faustin
    Faustin Posts: 1,149
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    @scubalab

    My pleasure!
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  • Clipdat
    Clipdat Posts: 12,599
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    audioluvr wrote: »
    These are what I'm using in my pre. I've bought 3 matched pairs because I like them so much and surprisingly they all sound the same.
    https://www.ebay.com/itm/163533485479

    @audioluvr The link doesn't load anymore. What kind were these?
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  • pitdogg2
    pitdogg2 Posts: 24,559
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    Knowing Rob I'm guessing some Raytheon black plate 12au7 organ tubes. In the past he has mentioned he really liked them.
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  • Clipdat
    Clipdat Posts: 12,599
    edited January 24
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    Oh ok interesting. I was trying to look into some balanced triode 12au7 tube pairs for my new ST-70.
    b2ommqrtsjse.png

    Supposedly rolling the rectifier can also improve things. Not in a big hurry though it still only has 3hrs play time.

    Edit: Also for anyone reading that's interested, this is the for sale ad where I purchased it: https://www.usaudiomart.com/details/650058317-dynaco-st-70-brand-new-custom-build-beautiful/

    Highly recommend this seller. Class act all the way.
    Post edited by Clipdat on
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  • pitdogg2
    pitdogg2 Posts: 24,559
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    https://www.ebay.com/itm/265322627696?

    Keep an eye open for some RFT 12au7 tubes. They can have many names on them and still be made by RFT. Earlier the better some very nice tubes. Hard to get, can be very pricey, boy will your ears thank you.
    5AR4 rectifier? Fat bottle Sylvania's and Mullard are the best.
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  • Clipdat
    Clipdat Posts: 12,599
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    Just link me Ivan, I'm ready to buy! TELL ME WHAT TO DO!
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  • pitdogg2
    pitdogg2 Posts: 24,559
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    I gave you a link :D:D
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  • Clipdat
    Clipdat Posts: 12,599
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    MOAR LINKS!
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  • bcwsrt
    bcwsrt Posts: 1,591
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    The man knows his tubes!!

    Brian

    One-owner Polk Audio RTA 15TL speakers refreshed w/ Sonicap, Vishay/Mills and Cardas components by "pitdogg2," "xschop" billet tweeter plates and BH5 | Stereo REL Acoustics T/5x subwoofers w/ Bassline Blue cables | Rogue Audio Cronus Magnum III integrated tube amp | Technics SL-1210G turntable w/ Ortofon 2M Black LVB 250 MM cart | Sony CDP-508ESD CD player (as a transport) | LampizatOr Baltic 4 tube DAC | Nordost & DH Labs cables/interconnects | APC H15 Power Conditioner | GIK Acoustics room treatments | Degritter RCM
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  • Clipdat
    Clipdat Posts: 12,599
    edited January 24
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    I'm stupid. On the link you provided it states:

    "Matched tested NOS pair of RFT 12AU7 tubes

    Tester mutual conductance: 2200/2200

    Tubes tested: 2350/2500, 2350/2200"

    Which of these number sets refer to the triode balance?
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  • pitdogg2
    pitdogg2 Posts: 24,559
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    Clipdat wrote: »
    I'm stupid. On the link you provided it states:

    "Matched tested NOS pair of RFT 12AU7 tubes

    Tester mutual conductance: 2200/2200

    Tubes tested: 2350/2500, 2350/2200"

    Which of these number sets refer to the triode balance?


    Tester mutual conductance: 2200/2200 < NOS would be this

    These tubes tested above NOS with the exception of one triode that tested AT NOS, tubes tested: 2350/2500, 2350/2200.

    They are very strong tubes. I have them in my watch list and If you do not I will buy them.


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  • pitdogg2
    pitdogg2 Posts: 24,559
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    https://www.ebay.com/itm/235221863064?

    https://www.ebay.com/itm/285653553623?

    https://www.ebay.com/itm/175837062765?

    https://www.ebay.com/itm/256388124281?

    https://www.ebay.com/itm/116048987511?

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  • Clipdat
    Clipdat Posts: 12,599
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    pitdogg2 wrote: »
    They are very strong tubes. I have them in my watch list and If you do not I will buy them.

    Ok ok I bought them!
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  • marvda1
    marvda1 Posts: 4,871
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    I was going to show you these, nice sounding tubes.
    https://upscaleaudio.com/products/ge-12au7-6189w?variant=37476278304952
    Amplifiers: Norma IPA 140, MasterSound Compact 845, Ayre v6xe, Consonance Cyber 800
    Preamp: deHavilland Ultraverve 3
    Dac: Sonnet Morpheus 2, Musical Paradise mp-d2 mkIII
    Transport: Jay's Audio CDT2 mk2, Lumin U1 mini
    Speakers: Rosso Fiorentino Volterra II
    Speaker Cables: Organic Audio Organic Reference 2
    Interconnects: Argento Organic Reference 2, Argento Organic 2
    Power Cables: Argento Organic Reference, Synergistic Research Foundation 10 and 12 ga.
    Puritan PSM156
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  • Clipdat
    Clipdat Posts: 12,599
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    Nice, I'd be down to get them from somewhere other than Upscale.
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  • Kex
    Kex Posts: 4,928
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    I thought Upscale were a reputable outfit. Is this not the case?
    Alea jacta est!
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  • Viking64
    Viking64 Posts: 6,679
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    Kex wrote: »
    I thought Upscale were a reputable outfit. Is this not the case?

    I took a wild guess and checked to see if this is the company with the guy some people tend to strongly dislike. Mind you, this memory was from something I briefly read/saw here maybe 5 years ago.

    Sure enough, I search for "upscale audio" and who do I see but Kevin Deal. I have no personal experience with this guy, but I recall him to be rather . . . polarizing. :D
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