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Discussion in 'Amps and Cabs [BG]' started by sdguyman, Mar 19, 2006.

  1. sdguyman


    Jan 31, 2003
    San Diego

    I was hoping that someone can help me out as far as the tube placement in the SVP PRO. I recently bought the SVP PRO from EBay and the guy shipped the preamp and tubes separately. Problem is he didn't realize that there is 1 12AU7 tube in there. He does not know where this tube goes. Can anyone help me out in placing the correct tubes back in the appropriate order?

    If you are facing the front of the preamp (were the knobs are) can you tell me what order they should be installed 1-5 left to right? (for example 1-12ax7 or ax for short 2-ax, 3-ax, 4-au, 5-ax)

    Thank you ahead of time for the info.
  2. brothernewt

    brothernewt Some people call me the stormtrooper of love...

    Apr 13, 2004
    Happyrock, OR
    pretty sure you put your example in the correct order. :eyebrow:
  3. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    That's it. The fun begins when you start thinking about what brands of tubes you want in each slot. :bassist:
  4. sdguyman


    Jan 31, 2003
    San Diego
    I'm thinking about buying Electro-Harmonix tubes. Anyone have any opinions on tubes?

  5. Ive never used them, i use JJ's in my SVT-II's preamp and love them :)

    www.eurotubes.com is a good place to order from

    Never used EH ones, just my $0.02 as you americans say ;)

    - Will
  6. I have an SVP Pro which came with Electro Harmonix tubes in it. I tried them for a month before deciding to see if I could get a better sound.

    This is Just my humble opinion but I found if I pushed the SVP with EH's even a little I started to get the bottoms drop off. Kind of like if you compressed the crap out of it, like it was kinda still there but all the fatness had gone. Also I noticed that the high end hiss that you will most definitely read about in these units suddenly appears. Then If I stop playing it continues to hiss. If I turn the unit off, suddenly no more hiss untill I drive it hard again.

    I had a techo mate loan me a set of JJ 12AX7C4's and a Nos Philips Miniwatt (Mullard) 12AU7A and I gotta say it improved by at least 20% in overall sound plus no hiss and the bottoms now dont fade out.

    I have just this moment put a set of 4 Ruby 12AX7C5's into the SVP and kept the Nos Philips (Mullard). The Rubys (so I'm told) are JJ's that Ruby select and test before relabeling them. I should be receiving one Nos Telefunken smooth plate 12AU7 and one Nos Telefunken Ribbed plate 12AU7 in a few days time. I need to do a few shows with the Rubys to make sure that I'm happy with them. Once thats decided I will swap and change between the TF Smooth, Ribbed and the Philips before making a final decision. (I'm told the TF Smooth is gonna win this race but we shall see.)

    After a few months of talking to other players and researching the web I have realised that you always need to ask one question before getting advice from other people regarding the SVP, "Does your playing style lean towards the Jazz end of the musical spectrum or the Rock end."

    I play no Jazz and almost all Rock of one kind or another. From what I have read of other peoples opinions this makes a huge difference to how players hear and regard the SVP

    Again, in my opinion, the SVP is mainly a Rock players style of preamp.
    I love it, it gives me all the tone, balls and cut that I have ever wanted.

    Finally I must agree with "i_got_a_mohawk" the JJ's are a safe bet. Lots of good feedback from different players on different forums. My recomendation for the 12AU7 is to get a Nos tube. Give me a few weeks of shows and I will be happy to give you my opinion between the TF's and the Philips/Mullard.

    Good luck

  7. sdguyman


    Jan 31, 2003
    San Diego
    I received the Electro Harmonix tubes yesterday and tested them out. I didn't experience the bottom drop off as you explained above. It could be that those tubes were old??? I don't know, the tubes that came with the SVP said that they were Chinese tubes and that is exactly what was happening. The other thing that happened with the old tube was once the peak indicator came on that was it it never turned off and the signal weakened. (In all honesty I thought I got a broken unit because I've never had this happen before with other pre-amps)

    The new tubes work great, no noise that everyone complains about these preamps. I'm using the preamp in a sort of non-conventional way, I'm plugging the output of the SVP Pro into the return of my GK700RB II, this way I can still use the bi-amp feature since I'm also using GK cabinets.

    The one feature I'm really starting to like is the boost on the head it give it a little more grind which is a beautiful thing. Now I have the option to choose between SS or Tubed.

    As far as style of music, I play jazz in a small group and the SVP Pro works great, tone-wise. Like you said Tone is subjective.
  8. Yep sdguyman, it is a definite possibility that the EH's in my SVP are old. And your description about the red led peak indicator is exactly what is happening. I would also not be surprised if the top end hiss that seems to only occur when pushed is directly related to the tubes being old as well. The Rubys that I received were unfortunately the 12AX7AC (Chinese) tubes not the Ruby JJ/Tesla 12AX7CZ's that I was expecting. I did a short review after trying them out which was posted in the 12AX7 thread here. I cant wait for the new Ruby/JJ's to arrive.
  9. bakus


    Feb 10, 2007
    hi sdguyman
    when you face your preamp you must place the tubes like this:

    12ax7 12ax7 12ax7 12au7 12ax7

    about the tubes you can choose "groove tubes"

    gt12ax7 & gt12au7

    eh's are also good but may be more destinated to hi-fi

    if you can read french,try the link underneath


  10. zippydog

    zippydog Supporting Member

    Dec 28, 2006
    I've been messing around with a number of tubes for my newly acquired used (ebay) SVP PRO.

    I'll spare you how I got there, but the config. I seem to like is as follows:

    V1-V3 Tung Sol 12AX7's
    V4 Amperex NOS 12AU7
    V5 The EH 12AU7 that came with the unit in V4

    I had a lot of hum noise with a 12AU7 in the V4 slot. Moving it to V5 helped a great deal to drive down buzz and hiss. Adding another 12AU7 to V4 helped a little more, but still getting a bit of noise.

    Other tubes I tried in every possible configuration were:
    JJ/Tesla 12AU7
    Sovtek 12AX7.


    I'll follow this thread with real interest - I had no idea before I got into this the difference a tube can make.

    There's another thread here that chronicles my journey in more detail. Here's the link:



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