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Topic: Steel Guitar Black Box and New Tube... |
Marlin Smoot
From:
Kansas
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Posted 1 Jul 2007 7:17 pm |
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| I've had my SSGB for the last 3 years and decided to change the tube. I went with the Groove Tubes Gold Series (GT-12AX7-M) and had excellent results. It's a Mullard spec tube according to the Groove Tube website. |
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Billy Murdoch
From:
Glasgow, Scotland, U.K.
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Posted 1 Jul 2007 11:16 pm
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Hi Marlin,
I too have a Black Box and would be interested to know if you NEEDED to change the tube.Had the sound deteriorated noticibly in order to prompt the change.
If your answer was that you changed only because of the length of time it had been in use could you say there was much of a change in performance.
Many thanks
Billy |
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Marlin Smoot
From:
Kansas
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Posted 1 Jul 2007 11:42 pm
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Billy,
My Black Box gets a lot of weekend use and has over the last 3 years. I wouldn't say it needed a change as it still sounded really good - however, I know tubes can make a difference and weaken over time so I decided to make a change.
The change I made did make a difference in the overall tone of the BB and brought back the nice low end and chimey highs, much like when it was new. I'm sure the old tube would have been ok for a good while, I felt the unit has been working hard over a long period of time, that I would see if a new tube would make a difference... and to me it did.
First I tried an Electro-Harmonix 12AU7A/ECC82EH as Brad suggested but I found it did not give me the 'edge' I liked, it was a very smooth sounding tube but I felt it lacked the magic (power?) I was looking for. The aforementioned tube I used (GT-12AX7-M) put the snap/edge back into the unit.
It's not something that will hit you hard, much like the BB, it will be very understated until you find the magic that the unit produces, but I think you'll begin to hear what the new tube does in short order as BB owners know what to listen for.
Hope this information helps... |
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Billy Murdoch
From:
Glasgow, Scotland, U.K.
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Posted 1 Jul 2007 11:48 pm
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Marlin,
Thanks for getting back so quick.
I bought a new tube from Brad when I was in Dallas in March and I WILlL install it now.
Best regards
Billy |
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Al Sato
From:
Texas Hill Country
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Posted 3 Jul 2007 6:22 am
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Thanks - this is quite a timely thread for me. I emailed Brad about it but I think my emails are getting blocked. I have well over 1000 hours on my BB with the original tube. I think I'll go change mine now.
Al
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So many stringed instruments, so little time... |
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Jamie Lennon
From:
Nashville, TN
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Posted 3 Jul 2007 6:23 am
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what is a black box ???
_________________
Mullen Guitars, Little Walter Amps, Benado Effects, D'Addario Strings
www.georgettejones.net |
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Jim Bob Sedgwick
From:
Clinton, Missouri USA
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Posted 3 Jul 2007 6:36 am
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| Jamie Lennon wrote: |
| what is a black box ??? |
Jamie... Go to links above... Manufacturers... related products. Brad Sarno's black box is listed under steel guitar black box. The website will explain it correctly.
It basically is a buffer preamp using a tube. The guitar plugs into the black box so that the pickup "sees" a tube before being routed into the amplifier. It adds a very slight amount of harmonic distortion, making a transistor amp have more of a tube vibe (warmer sound). I have one and it is well worth the investment. The unit is NOT a distortion device. Hope this helps. |
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Billy Murdoch
From:
Glasgow, Scotland, U.K.
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 9 Jul 2007 9:45 am
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I'm a bit surprised you would like a 12AX7, which has a nominal gain of 100, in the SGBB. The unit is specifically designed for a 12AU7 tube, which has a nominal gain of 20 - for example, see this recent thread with Brad's response: http://bb.steelguitarforum.com/viewtopic.php?t=108564
Although I'm entirely happy with the 12AU7 here, I was thinking about experimenting with different tube types, as well as some NOS 12AU7 tubes. I would be interested to hear what Brad has to say about this. |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 9 Jul 2007 10:07 am
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The BB is running a 12AU7 dual triode in two different stages. The input stage has a bit of gain (and color) which is then brought back down to unity. The second stage is a clean, unity-gain, 'follower' circuit which gives low-Z and a lot of current drive capability. If you use a 12AX7 in there, you will get a bit more gain in the front stage, but you'll also be operating that 12AX7 outside of its ideal range by pulling a bit too much current thru it. The circuit is definitely biased for a 12AU7. It probably sounds lively, but the 12AX7 may not last nearly as long as a 12AU7. You may lose a bit of clean headroom, but it may not be a problem with steel guitar causing clipping.
Also the output stage of the tube will not quite have the same current drive ability, but that's much less of a big deal since we're typically loading the BB down by a 500k to 1Meg volume pedal.
So really, go ahead and try it, but don't be surprised if the tube burns itself out a bit prematurely.
My favorite way to tweak a BB is to try the various 12AU7's and its actual substitutes. GE's and Sylvanias sound nice. RCA's are a bit hard and bright in there. I often use a GE 5814 which can easily be found as NOS. Go nuts and try a Brimar, Mullard, or Telefunken.
Brad |
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