AB pedal switching between preamps

Discussion in 'Amps and Cabs [BG]' started by Stewart13, Jul 27, 2019.

  1. Stewart13

    Stewart13 Supporting Member

    Jan 8, 2016
    Medford, Oregon
    to make a long story short, I’m wondering if I can use a Morley AB switcher to switch between preamps. I have a rackmounted Hellborg pre and a SansAmp. I’m plugged into the front of the Hellborg coming from the tuner which comes from my wireless. How I’m envisioning it is Hellborg pre out to A of Morley Sansamp pre out to B or Morley and output to my Hellborg power amp. Would this work? If anyone has any experience using an AB to switch between preamps let me know!! Thanks.
     
    Last edited: Jul 28, 2019
  2. Stewart13

    Stewart13 Supporting Member

    Jan 8, 2016
    Medford, Oregon
    Bumppppp
     
  3. Wasnex

    Wasnex

    Dec 25, 2011

    I know you could run the Morley in front of the preamps, but I am not certain it would be suitable after the preamps. The difference is the signal level. The owner's manual does not say what level the Morley can handle, but it does have warning: "DO NOT USE THE ABY ON A POWERED SPEAKER LINE! YOU WILL DAMAGE THE ABY, THE AMP AND THE SPEAKER(S)." This suggests it is not suitable for use with a line level signal. It's possible I am misinterpreting the warning.

    Edit I had originally proposed a Radial Twin City, but it is active so it only works Y to AB and not ABY.
    Not the right tool:bag:.
     
    Last edited: Jul 28, 2019
    Stewart13 likes this.
  4. Stewart13

    Stewart13 Supporting Member

    Jan 8, 2016
    Medford, Oregon
    Thanks for the reply. I’m not sure what they mean by powered speaker line either. Would probably help to be a little more specific on their end. Maybe I’ll give the Radial Twin City a shot.
     
    Wasnex likes this.
  5. Wasnex

    Wasnex

    Dec 25, 2011
    Okay I am striking out. I can't find a reverse ABY pedal that I can confirm will handle a line level signal.

    You could use a regular passive ABY like the Morley in front of the preamps so the bass is routed to one preamp or the other. Then the output of the preamps could be combined using something like a Radial Mix-Blender which drives the power amp. The problem with this solution is you would have the circuit noise from both preamps all the time. Another concern is making sure you have enough signal to drive the Hellborg power amp. The manual lists the sensitivity of the MP250, MP500, and SP250 as 0dBu, so that is probably not much of a problem

    If you don't need to control switching with your feet, perhaps a compact mixer with mute buttons or mic/line switching would work. Unfortunately none of the compact mixers I have found have these features.

    Another thing you could try is to use the effects loop on the Hellborg Preamp along with a regular passive ABY like the Morley before the preamps. This will work because the Hellborg has a parallel effects loop with a blend control. This means the loop can be setup so that it can receive an input from the effects return without bypassing the preamp. In other words you should be able to use the Effects Balance control to essentially mix the Hellborg preamp and the Sansamp. Also, the loop is switchable between -10dB to +4dB so it will handle either instrument level or line level signals. To try it out, plug your Sansamp into the Effects return, set the level to match the output of your Sansamp, and adjust the blend.
     
  6. Stewart13

    Stewart13 Supporting Member

    Jan 8, 2016
    Medford, Oregon
    A366013B-9532-4FA0-9FD0-E7C56072C020.jpeg So where does the ABY box go in this equation? I also use a wireless system just to let you know.
     
    Last edited: Jul 28, 2019
  7. Wasnex

    Wasnex

    Dec 25, 2011

    If you want to try running the Sansamp into the effects return the ABY goes between the wireless and the preamps. Before buying the ABY, I suggest connecting the Sansamp to the Effects Return and seeing if you can set all the levels so that you can use both preamps with good tone and volume and acceptable noise. Just manually patch your wireless from one preamp to the other.

    If it works well enough with manual switching, I think an active reverse ABY (amp switcher) like the Radial Twin City is probably a better choice than a passive ABY. Passive ABYs are likely to have switching noise and may have no means of dealing with ground loops. The down sides I can think of is the Twin City must be powered (9V), and it will cost a bit more.