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    Octal driver for M125

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    cci1492

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    Re: Octal driver for M125

    Post by cci1492 on Wed Apr 26, 2017 10:07 pm

    Thank you Kentley! So should the BH7 be installed on the front?
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    Kentley

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    Re: Octal driver for M125

    Post by Kentley on Wed Apr 26, 2017 10:18 pm

    I suggest you try it in the front. This one tube could be the most crucial for overall tone. Or two tubes, one in each monoblock.
    My experiences with 12BH7s in my ST-120 were generally quite good. And there's a ton of possibilities on the market. RCAs I found to be creamy and mellow, GEs sharper, but my faves are vintage TungSols. Strong and clean.
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    cci1492

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    Re: Octal driver for M125

    Post by cci1492 on Wed Apr 26, 2017 10:25 pm

    Done, thanks again.
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    deepee99

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    Re: Octal driver for M125

    Post by deepee99 on Thu Apr 27, 2017 1:12 am

    Kentley wrote:
    cci1492 wrote:From the info I gathered from this thread, I pulled the RCA 5963s from the rear part of the driver board of the M125s and replaced with GE 12BH7As from a sleeve of 5 purchased last year that I never used. They still sound incredible, have not heard enough to tell a difference. Didn't realize they are a little taller too. Will be interesting to see what dog has to say about a 6SN7 instead in that spot. So on the M125 the front 12AU7A is an inverter and does not have to match the rear?

    It's the other way around. The front tube is the volt-amp, the rear is the phase inverter. Most of us agree that the front tube will have the most influence on the sound. That said, the importance of a well-functioning and nicely balanced dual-triode in the inverter position should not be underestimated. Cheers. drunken

    Yeah, what Kently said. Don't neglect the back toobs, but put your best out front of the M-125s or mid-position in the ST-120s.
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    cci1492

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    Re: Octal driver for M125

    Post by cci1492 on Thu Apr 27, 2017 8:34 am

    deepee, I miss understood this line:
    Kentley wrote:Side drivers on the ST-120, rear driver in the M-125 - no conceivable reason to make the switch.
    but now i got it, youz guyz are great!
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    cci1492

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    Re: Octal driver for M125

    Post by cci1492 on Fri Apr 28, 2017 12:48 pm

    I ordered a couple of the adapters that Kenley had suggested to go from the 9 pin to the 8. So now I'm looking at some 6sn7s on ebay. There are a lot of junk collectors selling toobz! Does this seem like the kind of stuff to look for?
    http://www.ebay.com/itm/192029678079?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
    I'm going to wait until I have the adapters before ordering so I can test them right away, but to get an idea. Thanks.

    Dogstar

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    Re: Octal driver for M125

    Post by Dogstar on Fri Apr 28, 2017 3:24 pm

    I'm skeptical of any eBay seller nowadays.
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    cci1492

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    Re: Octal driver for M125

    Post by cci1492 on Fri Apr 28, 2017 3:54 pm

    I was burned on a dewalt sliding compound miter saw few years ago ($460). I had to wait almost 3 months to get my dough back from ebay. Many crooks out there.
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    Kentley

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    Re: Octal driver for M125

    Post by Kentley on Fri Apr 28, 2017 3:55 pm

    eBay is a crapshoot for sure. I've gotten great deals and junk - sometimes from the same seller.
    Here's a great place to start. This guy knows his tubes - and he's what you might term a "real character" to boot:
    http://vintagetubeservices.com/octal-tubes/
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    cci1492

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    Re: Octal driver for M125

    Post by cci1492 on Fri Apr 28, 2017 4:09 pm

    Kentley thanks again! What does he mean by "Moving-Mag, Super-Line, & Line" I have to assume quality as the price drops as you look down the list. drunken again, no too early!
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    deepee99

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    Re: Octal driver for M125

    Post by deepee99 on Fri Apr 28, 2017 4:14 pm

    Never been burned by Andy Bowman at http://vintagetubeservices.com/octal-tubes/
    And as Kentley sez, a conversation with Andy is always fun. A caveat: Do not email him and expect a reply within the next millennium or two. A phone call is all ya need.
    For new reissue tubes, Jim McShane is your man. There are a couple of very decent re-sellers in China and Turkey for NOS stock as well.


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    deepee99

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    Re: Octal driver for M125

    Post by deepee99 on Fri Apr 28, 2017 4:20 pm

    cci1492 wrote:Kentley thanks again! What does he mean by "Moving-Mag, Super-Line, & Line" I have to assume quality as the price drops as you look down the list. drunken again, no too early!
    Moving magnet and moving coils are phono pre-amp related, depends on your cartridge. MCs are very low output and need the greatest amplification. So they've got to be extremely quiet and upper and lower triode matched carefully.
    Most tubes that aren't grunty or microphonic will work OK in a line pre-amp. Then you open a whole can of worms asking which are best in which slots.

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    cci1492

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    Re: Octal driver for M125

    Post by cci1492 on Fri Apr 28, 2017 4:27 pm

    ah, ok, that makes sense, just never heard of a TT pre-amp that uses an octal.

    eickmewg

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    Re: Octal driver for M125

    Post by eickmewg on Fri Apr 28, 2017 7:12 pm

    Over on Audio Karma, I got some great 6SN7 tubes from user HyKlas. Snagged a quad of matched Sylvania 6SN7GTB's for $30. Dead quiet tubes. I think he has many more for sale. Perhaps a PM to him might yield some great tubes for little money.

    Bill
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    skriefal

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    Re: Octal driver for M125

    Post by skriefal on Fri Apr 28, 2017 10:36 pm

    Most tubed phono pre-amps do use the smaller tubes -- 12AX7, 12AU7, and 6DJ8/6922 being the most common.  A couple that do use octals are the Tavish stage (uses 6SL7s), and Mapletree's Phono 3C (uses 12SN7).  I don't recall seeing any that use 6SN7s - but there's probably something out there.

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