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In Reply to: Re: Cascode -vs- No-Cascode posted by Paul Speltz on June 15, 2001 at 15:28:55:
This weekend I doubled the current through the gain stage by adding a parallel 38k resistor across the existing 38k current set resistor on the cathode of V3, the CCS tube. I also added a parallel 100k resistor across each of the two existing 100k plate resistors, thus making them 50K ohms. This doubles the current through the tubes without altering the plate voltage.The sound of the no-cascode (V2 removed and bypassed) improved some with twice the current.
The sound with the cascode improved nicely. It pulls the music into a sharper focus. The benefits are similar to the no-cascode tweak but without losing so much gain. It also reminded me of the benefits I got when I added the SLCF. I didn't notice any loss of "jump" either. Try it..you will like it. If you don't like it, take two minute and cut the resistors out.
Today I took the amps into the lab, and Ralph was right. Looking at the Cascode and doubling the current I saw:
1) The gain dropped by 2.4dB
2) Bandwidth increased by about 35%
3) The linear region is reduced from 180 V p-p to 125 V p-p. This may not be noticeable. I'm not sure how much voltage swing is needed on a stock amp at full power.
This is such an easy tweak, and so easy to reverse that you should give it a try. But don't listen to what I say, trust your ears and tell us what you hear in your system. Results may vary.
Paul Speltz
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Follow Ups
- Re: Double Cascode Current Results - Paul Speltz 21:22:19 06/17/01 (3)
- Re: Double Cascode Current Results - Barry Landis 19:32:52 06/18/01 (1)
- Re: Double Cascode Current Results - Paul Speltz 08:22:46 06/19/01 (0)
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