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K&K Audio / Lundahl Transformers

OPT for SE84CS Monoblock Upgrade

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I am tri-amping my system with Decware SE84CS's. I am thinking of replacing the two OPT in my selects with one Lundahl for the woofer driver for better bass extension. I'll run both SV83's in parallel through a single OPT. The LL1620-80mA seems the best choice (running at 11.5K primary to keep the same sonic signature as the other two SE84CS's running my mids and tweeters). I just hope that the 80mA limitation isn't too low for two SV83's in parallel.
Any opinions or other options?
Thanks
DanL

Follow Ups:

Re: OPT for SE84CS Monoblock Upgrade - KevinC 05:45:21 08/09/03 (1)
Well, it should be possible to do what you describe. Since the SV83 is used strapped for triode and seems rather similar to a 6BQ5, a reasonable plate impedance load for a single tube is perhaps 6K. That would argue for a reasonable load for two tubes in parallel SE of 3K. This is at odds with your idea presented above, so let me ask a couple of questions. What is the primary impedance of the stock output transformer? What is the voltage drop across the SV83 cathode resistor? With these questions answered we can get to the bottom of this issue.

Kevin Carter
K&K Audio
www.kandkaudio.com
- Re: OPT for SE84CS Monoblock Upgrade - danlaudionut 15:14:28 08/09/03 (0)
  Kevin C
  I haven't bought them yet as I'm waiting for my family's estate to be settled (10 months and counting), but their OPT is 9.8K/6 ohm. They recommend that you bridge them in series for better bass response, so the OPT would then be 19.6K. I was thinking that 11.5K would be in between the two. I could tune it to the best point with different output configurations. The idea is that you have lower distortion with a higher impedance OPT and greater low impedance drive therefore better cone control and more headroom, but giving up gain. I've read that C-core OPT have the best bass that is why I'm thinking Lundahl. So I guess I'll have to wait to assemble one to get more of the specifics on their operating point before I can choose the right OPT.
  I'm also thinking of choke loading their 6N1P (resistive loading is stock) to get a little more gain out of it (2V for rated output) since I'm going to be using a tube buffered passive pre/crossover (Steve Bench design with 6DJ8 cathode followers) with my DAC output of only 2.5V (Sonic Frontiers SFD-1 MKII). How much inductance do you recommend - the more the better? Maybe use their stock OPT as the choke loads or try different chokes for the tweeter's amp, mid's amp and woofer's amp?
  Crossover frequencies are 400 and 5K.
  Tweeter Dynaudio D260
  (simply awesome when used above 5K)
  Midrange Focal 5K4411
  (5" Kevlar w 1.5" VC and phase plug)
  Woofer HiVi D10G
  (10" paper/Kevlar w 4"VC and Neodynium Magnets)
  Thanks
  DanL

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