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    Mullard KT88

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    DavidR

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    Mullard KT88

    Post by DavidR on Tue Oct 31, 2017 6:44 pm

    Has anyone used the Mullard KT88 in a ST-120. Curious as to the sound, etc.
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    peterh

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    Re: Mullard KT88

    Post by peterh on Tue Oct 31, 2017 7:03 pm

    DavidR wrote:Has anyone used the Mullard KT88 in a ST-120. Curious as to the sound, etc.
    Mullard never made kt-88. ( the dutch/english company Mullard)
    Sovtek that bought the brand name mullard does however make kt-88 and sells them
    under the name Mullard. Confusing ?

    If they are properly made ( which they are supposed to ) they should sound like any
    other kt-88

    The question is similar to asking "what brand of lightbulb is best in my desklamp ?"
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    sKiZo

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    Re: Mullard KT88

    Post by sKiZo on Tue Oct 31, 2017 7:29 pm

    Of the new production tubes I've tried, I'm kinda sorta partial to the TAD KT88STR. Supposed to be an exact clone of the vaunted MOV - heavy glass and evarthang. They DO take a while to break in properly,but they're worth the wait.

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    deepee99

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    Re: Mullard KT88

    Post by deepee99 on Wed Nov 01, 2017 1:32 pm

    Who builds the TADs? I've heard so many different answers I can't suss it.

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    Dave_in_Va

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    Re: Mullard KT88

    Post by Dave_in_Va on Wed Nov 01, 2017 3:58 pm

    I've always read (on guitar gear head sites) that TAD sold in the USA are Chinese tubes but the situation may be different in Europe.
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    sKiZo

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    Re: Mullard KT88

    Post by sKiZo on Wed Nov 01, 2017 5:46 pm

    Yup on the Chinese. Last I heard, Shuguang was their go to supplier.

    But ...

    The tubes are produced to TAD's specs, AND they do a full test and burn in once they get em. Rumor has it they reject a LOT of tubes before putting their brand on the bottle. I imagine those end up going back to the factory and resold under another label.

    Also had the same question, and here's the factory response:

    The KT88-STR have exceptional stability in electrical specs. This results from superior material purity we selected for its design, the extended factory burn-in and our rigid testing here in Germany. The KT88-STr is the only KT88 on market with consistently low Ig1 < 200nA at 500V Ua and Ug2 operating. The Premium Matching (RT89 part number) includes the matching for dynamic parameters which results in the “perfect” sonical performance.


    PS - their US supplier is MojoTone, but I got mine direct from Germany.

    ** I also have a full complement of their tubes in my Eico mono - also quite nice.

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    Dave_in_Va

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    Re: Mullard KT88

    Post by Dave_in_Va on Wed Nov 01, 2017 6:04 pm

    "The tubes are produced to TAD's specs, AND they do a full test and burn in once they get em."

    Yeah, maybe.
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    DavidR

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    Re: Mullard KT88

    Post by DavidR on Fri Nov 03, 2017 4:18 pm

    [quote="peterh"]
    DavidR wrote:..............................................................

    If they are properly made ( which they are supposed to ) they should sound like any
    other kt-88

    The question is similar to asking "what brand of lightbulb is  best in my desklamp ?"


    Some people think all amplifiers sound a like. NOT.
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    DavidR

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    Re: Mullard KT88

    Post by DavidR on Fri Nov 03, 2017 4:21 pm

    I'll try again. I have an ST-120 with Sovtek 6550 output tubes. I am happy with the sound BUT I'd like to try something else. I like good bass and detail in the treble. Any recommendations?
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    Bob Latino
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    Re: Mullard KT88

    Post by Bob Latino on Fri Nov 03, 2017 8:06 pm

    DavidR wrote:I'll try again. I have an ST-120 with Sovtek 6550 output tubes. I am happy with the sound BUT I'd like to try something else. I like good bass and detail in the treble. Any recommendations?

    First off the Sovtek 6550WE output tubes are excellent well balanced tubes for the money. If you feel that you need maybe just a slight more top end, you might try a matched quad of of the Gold Lion KT88's. Note > If your amp is new, you should really let all the tubes break in for at least 100 hours or so before making tube changes. After 100+ hours, the tubes should be fully broken in and the sound of the amp should stabilize.

    A less expensive way to alter the sound of the amp is to try different center driver tubes. The center (voltage amplifier tube) has a lot of influence on the sound of the amp and affects BOTH channels. There are MANY tubes to try here. You can use any 12AU7, 12BH7 or the military/industrial versions of the 12AU7 > the 5963, 5814, 6189 and the CV4003. These tubes can be found at reasonable prices except for the CV4003 which is a Mullard made tube and commands high prices ($50+ USD each). It's a lot easier on your wallet to replace a $12 - $20 12AU7 type tube than to commit $200 USD for a matched quad of Gold Lion KT88's.

    Bob
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    DavidR

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    Re: Mullard KT88

    Post by DavidR on Fri Nov 03, 2017 9:38 pm

    Thank you Bob for the very well stated and complete answer. The amp is broken in. Many people have said that you get a lot of bang for the buck with the Sovtek 6550 tubes. Bass is very good and treble detail is good. I'm currently running RCA 6680/12AU7A on the 2 outside tubes and an RCA 12BH7A in the center. I have picked up pair of GE 12AU7A and a Tung-Sol 12BH7A, a pair of Tung-Sol 12AU7W and a Gold Lion GZ34 rectifier. I ran them a limited amount of time and found the Tung-Sol very sweet. I just got a Mullard CV4003 today but have not tried it yet. I'm not planning on tube rolling but rather just prepared with spare tubes. Several people have stated the Gold Lion KT88 tubes have a SS sound and not very tubey. Perhaps the Sovtek are the best for me but just wondering about others. So opinions and experiences on alternate output tubes would be great.

    tubed1

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    Re: Mullard KT88

    Post by tubed1 on Fri Nov 03, 2017 11:17 pm

    Russia-made Electro-Harmonix 6550 output tubes float my boat.  although, I have not heard these in the VTA125 or ST-120.
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    sKiZo

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    Re: Mullard KT88

    Post by sKiZo on Fri Nov 03, 2017 11:32 pm

    Agreed - center driver is the BIG one for altering the sound of these amps, but ...

    ... let's not discount the difference the power tubes can make. Bass is noticeably more detailed and pronounced with my KT120's in the ST120, but the TADs have a better defined midrange. Kind of a carp shoot which is more important to me, mostly depending on what I'm listening to.
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    DavidR

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    Re: Mullard KT88

    Post by DavidR on Sat Nov 04, 2017 6:42 pm

    I tried the Mullard today in the center driver position. Ooohhhh................nice.
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    ArlanB

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    Re: Mullard KT88

    Post by ArlanB on Sun Nov 05, 2017 12:34 am

    I have one of the first VTA ST120 kits from Bob that has the high gain board using 12AT7's,  I have a set of Mullard CV4024's that have been in service in the amp for 9 and a half years and are still going strong.  Can't say the same for the power tubes.  Went through 4 different sets of quads of KT88's from the eastern block countries in two years, then tried a quad of Penta Labs KT88SC from the Shuguang Factory that lasted over 6 years before on red plated last November.  Unfortunately Penta stopped marketing their KT88.  So I found that The Tube Store is marketing the same tube under their lable. I replaced the Pentas with the Tube Store KT88's.  They look to be exactly the same as the Pentas and am very happy with their sound.
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    DavidR

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    Re: Mullard KT88

    Post by DavidR on Sun Nov 05, 2017 10:01 am

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    deepee99

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    Re: Mullard KT88

    Post by deepee99 on Mon Nov 06, 2017 2:25 pm

    Has anyone tried the EAT KT-88s yet? A bit out of our budget but I'd be tempted, tempted, tempted . . .
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    sKiZo

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    Re: Mullard KT88

    Post by sKiZo on Mon Nov 06, 2017 3:33 pm

    EAT what?

    clown

    I'm also a fan of being able to control the line levels throughout the audio chain. My system's adjustable at each step, and that can make a significant difference in SQ.
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    Kentley

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    Re: Mullard KT88

    Post by Kentley on Mon Nov 06, 2017 6:56 pm

    sKiZo - "I'm also a fan of being able to control the line levels throughout the audio chain. My system's adjustable at each step, and that can make a significant difference in SQ."

    I totally agree with you. An added benefit of this practice is the ability to maximize S/N ratio.

    Dogstar

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    Re: Mullard KT88

    Post by Dogstar on Tue Nov 07, 2017 1:29 am

    ArlanB wrote:I have one of the first VTA ST120 kits from Bob that has the high gain board using 12AT7's,  I have a set of Mullard CV4024's that have been in service in the amp for 9 and a half years and are still going strong.  Can't say the same for the power tubes.  Went through 4 different sets of quads of KT88's from the eastern block countries in two years, then tried a quad of Penta Labs KT88SC from the Shuguang Factory that lasted over 6 years before on red plated last November.  Unfortunately Penta stopped marketing their KT88.  So I found that The Tube Store is marketing the same tube under their lable. I replaced the Pentas with the Tube Store KT88's.  They look to be exactly the same as the Pentas and am very happy with their sound.

    I did not realize there are three driver boards now as it seems from what I'm reading here.
    The first being the original which uses novel socket board that uses 12AU7's, the second being the octal socket board that uses 6SN7 and now the third which is also a novel socket board that uses 12AT7's. Is the true?

    So if it is what is the differences between them as far as sonic characteristics and output. To use the term sonic quality probably shouldn't be used since it's really a matter of personal preference?

    Does the 12AT7 board draw more current than the 6SN7 board? I imagine the transformers in the VTA ST-120 are more than capable of handling the differences as well. Is the correct too?
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    DavidR

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    Re: Mullard KT88

    Post by DavidR on Tue Nov 07, 2017 12:44 pm

    Dogstar wrote:
    ArlanB wrote:I have one of the first VTA ST120 kits from Bob that has the high gain board using 12AT7's,  I have a set of Mullard CV4024's that have been in service in the amp for 9 and a half years and are still going strong.  Can't say the same for the power tubes.  Went through 4 different sets of quads of KT88's from the eastern block countries in two years, then tried a quad of Penta Labs KT88SC from the Shuguang Factory that lasted over 6 years before on red plated last November.  Unfortunately Penta stopped marketing their KT88.  So I found that The Tube Store is marketing the same tube under their lable. I replaced the Pentas with the Tube Store KT88's.  They look to be exactly the same as the Pentas and am very happy with their sound.

    I did not realize there are three driver boards now as it seems from what I'm reading here.
    The first being the original which uses novel socket board that uses 12AU7's, the second being the octal socket board that uses 6SN7 and now the third which is also a novel socket board that uses 12AT7's. Is the true?

    So if it is what is the differences between them as far as sonic characteristics and output. To use the term sonic quality probably shouldn't be used since it's really a matter of personal preference?

    Does the 12AT7 board draw more current than the 6SN7 board? I imagine the transformers in the VTA ST-120 are more than capable of handling the differences as well. Is the correct too?

    You might want to make this a separate thread. A search might not find it.
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    DavidR

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    Re: Mullard KT88

    Post by DavidR on Tue Nov 07, 2017 12:45 pm

    Well, I'm going to go with the Tung-Sol 6550 or the Mullard KT88 just to try something different. I might end up flipping a coin to decide.
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    Dave_in_Va

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    Re: Mullard KT88

    Post by Dave_in_Va on Tue Nov 07, 2017 12:52 pm

    "I did not realize there are three driver boards now as it seems from what I'm reading here.
    The first being the original which uses novel socket board that uses 12AU7's, the second being the octal socket board that uses 6SN7 and now the third which is also a novel socket board that uses 12AT7's. Is the true?"


    The 12AT7 board is an older one. The current one is the 12AU7 board.
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    ArlanB

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    Re: Mullard KT88

    Post by ArlanB on Tue Nov 07, 2017 6:56 pm

    Yes the driver board with the 12AT7's was the original driver board supplied with the VTA ST120.  In 2008 when I purchased my VTA ST120 the high gain board using 12AT7's was what was supplied with the kit.  About 2012 Roy canged the driver board to use 12AU7's for a lower gain and this became the standard board supplied with Bob's kits.  The 12AT7 works well for me, they sound great and are very durable.  The set in my amp are Mullard CV4024/12AT7 and are the original triplit that I installed.  They are now 9 years old and still going strong.  I have 8 more in my spair tube kit and at the present rate of failure they will out last me.
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    GreggW

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    Re: Mullard KT88

    Post by GreggW on Wed Nov 08, 2017 3:17 am

    My 120 has the high gain board, JAN Philips 12AT7s on the outboards and a Mullard CV 4024 in the center. This combo sounds so good I won't change it. I was gifted a set of EH6550s last year; I like them too...

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