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12-05-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,540
Joined on 05-28-2004

Post #: 1
Post ID: 6057
Reply to: 6057
Super Melquiades, Macondo and Class A2

I do not know why people go into low-sensitive loudspeaker and they go crazy in order push the last drop out of the class A2 operation. From a different perspective the Macondo’s woofer towers with 97.5dB sensitivity are low low-sensitive loudspeakers – so how Super Milq’s low frequency channel behaves when it drives 6C33C into A2? Armed with Dima’s lecture about details of A2 operation I desired to measure it in my own setup. At Super Melquiades full power, max preamp output (unity gain) and playing regular symphonic repertoire I was able to develop at the very stressful orchestral moment no more than 30V AC on the 6C33C’s grid. Considering the minus 92V of 6C33C bias the Milq is far from A2.  Well, I need higher stress I figured and I employed the contemporary loud, compressed, electronic music. I took Leonard Cohen’s album “Ten New Songs”, the beginning of the cut “In my Secret Life”. When I maxed out my preamp, I was forced to stay dos one channels as it was imposable to stay in the room – it was VERY loud. I was playing right channel and measuring the proximity of   6C33C’s grid AC voltage to bias voltage. At a few peaks the stage did entered into A2 and the peaks were clipped quite aggressively and 6E5P has preassembly no current to drive it. However, I was not able to do it for a long time as it is cool in Boston, the window are closed and I was afraid that bass could break the windows in my home – it was intolerably and earsplittingly loud.

I set the preamp at a few dB down and set the volume to very loud, I would say 10-12dB louder then I would normally listed this music. Then I monitored the 6C33C’s grid AC voltage – it did not enter the class A2. Below is a photograph made with exposure of 8 seconds. It is 10V/div, with one channel (top line) set the bias voltage (-92V) and “0” volts at 9 division down – one division above. I think the commentaries are not necessary. With Classical music I was getting even less AC voltage swing….

Rgs, Romy the caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
Page 1 of 1 (1 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  The 6E5P tube data...  Bartola Valves: 6e5p beam tetrode SPICE model...  Melquiades Amplifier  Forum     44  322633  07-23-2007
  »  New  The Melquiades bass channels: the coupling capacitor...  bias continued...  Melquiades Amplifier  Forum     11  84184  08-13-2007
  »  New  Small SET’s bass, besides everything- is it about power..  Importance of OPT and type of tube for SET amp bass per...  Audio Discussions  Forum     4  61407  01-12-2009
  »  New  The low-power SET and dead speakers..  Expiring Cygnets (Back to Bass-ics)...  Audio Discussions  Forum     2  21798  01-18-2009
  »  New  More power from Melquiades? More powerful tube?..  A new Icon Audio's MB81 Mono Blocks...  Melquiades Amplifier  Forum     19  174351  09-01-2007
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