herf
Junior Member
Posts: 80
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Post by herf on Apr 9, 2007 22:48:55 GMT -7
Is the Route 66 a class A or AB amp?
I'm going to put in new JJ KT-66's into my Route 66. Calculations for biasing on Ted Weber's site are different depnding on whether or not the amp is class A or AB.
I'll let you all know how it goes. Especially any tone changes.
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Post by John on Apr 10, 2007 3:29:14 GMT -7
None of the Doc's amps are true Class A. Several are 'cathode biased' which is often confused as Class A. But the Route 66 is Class AB.
Myles Rose of Groove Tubes and resident expert in this forum says the Route 66 should be biased at about 36 ma.
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Post by iggs on Apr 10, 2007 6:44:47 GMT -7
Is the Route 66 a class A or AB amp? I'm going to put in new JJ KT-66's into my Route 66. Calculations for biasing on Ted Weber's site are different depnding on whether or not the amp is class A or AB. I'll let you all know how it goes. Especially any tone changes. Class AB ... please let us know how those JJ's work in RT66. Fingers crossed you don't see the fireworks like with the Tung-Sol KT66.
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herf
Junior Member
Posts: 80
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Post by herf on Apr 10, 2007 6:57:38 GMT -7
They do not have the metallic base like the Tung Sols and Bob at Eurotubes assured me they would work fine in a R66.
Note: the base on these is wider so the standard bear trap style tube retainers have to be removed (or flattened).
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Post by Hohn on Apr 11, 2007 23:31:31 GMT -7
Class of operation is related to where the amp is biased. You can operate a class AB amp VERY close to A or very far away. The higher the idle current, the closer to Class A. The lower it is, the closer to Class B. Class B is NO idle current, which is quite efficient but generates a lot of switching noise as the waveform swings from positive to negative.
Things also change with state of operation. Some amps can be class A when clean, and AB when overdriven (or was it vice versa?)
Anyway, the "class of operation" has also to do with circumstance (overdriven vs clean) and settings (bias) not just design parameters.
Justin
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Post by Phil (aka Phil) on Apr 18, 2007 6:05:51 GMT -7
None of the Doc's amps are true Class A. Several are 'cathode biased' which is often confused as Class A. But the Route 66 is Class AB. Myles Rose of Groove Tubes and resident expert in this forum says the Route 66 should be biased at about 36 ma. The Dr. Z Mini is (was) true Class A operation. PDW
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Post by John on Apr 18, 2007 7:51:14 GMT -7
Ah, PDW is right, the Mini is (was) true class A
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