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Post by myles on Sept 17, 2008 15:51:46 GMT -7
This is a copy of what I just finished as a test report. If you wish a copy of the test report in detail please email me at myles@65amps.comHere is a copy of the results from the JJ 803S testing. Briefly, the gain on these tubes in closer in design spec than anything else on the market currently in production. The same sort of spec is also held by the JJ ECC83S in regard to gain. Most current production tubes have a typical true gain of 80-85 at best. The average plate resistance of 60.2k is far better than current industry production averages. 62.5k is the spec and most tubes fall below 50k. This proper plate resistance spec is one reason the JJ tubes have gain that is better than any Sovtek or China offering as a general rule. The transconductance and plate current output vary widely off spec but the gain range is within a very nice range. You may want to send a copy of this to JJ as perhaps they can become even more consistent if they addressed the plate current and transconductance issues. These particular tubes were some of the finest current production types I have tested. Myles
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Post by (8^D) on Sept 17, 2008 17:14:49 GMT -7
Cool! Thanks for posting the results/comments!
Dan
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Post by asattwanger on Sept 17, 2008 17:55:34 GMT -7
yeah, I put a set of those things in my Mesa head for the clean channel and one of them is highly microphonic.
Matter of fact the 803's 6v6's & 6l6's developed a rattle issue and none of them have seen that much play. I'm seriously bummed with my last JJ buy. At least all 8 of the El-84 were good.
Good lesson. Don't ever re tube amps and let them sit. Ride them hard for the amount of time they are under warranty and if they are good then let it sit.
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Post by myles on Sept 17, 2008 18:20:46 GMT -7
yeah, I put a set of those things in my Mesa head for the clean channel and one of them is highly microphonic. Matter of fact the 803's 6v6's & 6l6's developed a rattle issue and none of them have seen that much play. I'm seriously bummed with my last JJ buy. At least all 8 of the El-84 were good. Good lesson. Don't ever re tube amps and let them sit. Ride them hard for the amount of time they are under warranty and if they are good then let it sit. Part of the reason they may be more prone to physical microphonics is because they have higher gain than other production tubes. This was also a Telefunken and Ei long smooth plate issue.
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