SET Asylum

RE: how to multiamp a SET

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Valvulator

A

In Reply to: RE: how to multiamp a SET posted by Saturntube on April 30, 2012 at 14:48:30

Thanks Saturntube,

So I guess than using a SET for the low frecuency is not a foolish thing (i dont reach much info on the net about 4 SET monoblocks to attack a passive filter on 2 way speakers)

Merlins have a Zobel net set (one for hight freq. other for low freq.) At the moment I only used Zobel for the high freq.) I may change my needs if I decide using 4 SET amps configuration. Is than someting similar to PLLXO (resistor an a cap) that you propose? Zobel is made of something that looks like a Hovland Cap and other ting that looks like a transistor??: http://www.merlinmusic.com/howto_sglwrg.htm

Thanks again...

Follow Ups:

RE: how to multiamp a SET - Saturntube 07:15:19 05/01/12 (0)
Hello Valvulator,

I dont know about the particular design of the Merlin and its zobel network, but it is there to correct the drivers response, so try to leave it on. When you multiamp hook the zobel to just one set of binding posts, either the top or the bottom one, try it both ways and without, see what you like better.

You should always try to respect the designers xover, if he is any good, he spent a long time setting it! What you do with the Passive Line Level Xover is unload the frequencies which the amp is not working at so it is less stressed. You should know the Xover point, the frequency in which the original Xover is set so you can make the PLLXO accordingly. Maybe send an email to Merlin and have the designer tell you how to hook up the Zobel and the Xover points.

Sets for bass is a great luxury, I am mutliamping and sadly I have to use SS for bass, and had to adjust my bass system to that.
RE: how to multiamp a SET - Valvulator 04:52:04 05/01/12 (3)
I see Merlin Zobel net provided is a RC net consiting on a Hovland cap and a resistor; yes.

One thing I love single ended triodes for theyr pure sound. Putting 4 amps would change this, will this sume the valve errors as in a Parallel Single Ended disign??

Thoughts on this??
- RE: how to multiamp a SET - Saturntube 07:20:25 05/01/12 (2)
  What amps are you using?
  
  Mono amps are the same as stereo amps, but with a power supply for each channel, this helps on better separation betweena the channels and less setressed power supply... two monos equals one streo amp.
  
  No this wont be at all as Parallel Single ended.
  
  If you use 4 Stereo amps and parallel the outputs of both channels on the stereo amp to one output, then it would be like a P-SET.
  - RE: how to multiamp a SET - Valvulator 11:35:18 05/01/12 (1)
    My amps are mono; Unison Research Smart 845's.
    
    I'm happy to read that 4 mono amps is not like parallel single ended.
    
    I have tested the 4 on my speakers but resoults is bad, there may be different reasons, amps are the same but there are some mods made:
    
    .output valves; 845B aprox. 22w. vs. and 845M aprox. 20w.
    .driver valves; ecc99 vs. e80cc
    .6bd's negative Feedback vs. no NFB
    .different signal coupling caps; polypropilen vs. teflon.
    .resistor on the electrolitics vs. FREDS (fast recovery diodes)
    
    ...
    
    May this make such a huge difference to make them incompatible??? What Ive heard sais YES...
    
    What do you think??
    - RE: how to multiamp a SET - Saturntube 08:18:43 05/03/12 (0)
      Well what you hear is what matters!
      
      Have you tired them using the two identical monos on one side? maybe that can help.
      
      When multiamping doesnt work it is awful! but sometimes it takes a little time to notice, since you will be amazed by the nice effects you get, the you realize all else is messed up.
      
      If you are up for it, try a Line level xover, sometimes the overlap between the two drivers is big and that makes the differences in amps more noticeable. It can be active or passive. Try Marchand audio, they carry both PLLXO and active.
      You will need to know the Xover frequency, ask the designer.
      
      Maybe it wont work with this amps, but if you make it work, you will be very happy with the results!

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