JapanAxe Posted October 18, 2013 Share Posted October 18, 2013 (edited) I have just bought some NOS Sylvania 12AX7WA valves to use in the preamp of my Streamliner 900 (thanks walbassist!). However, before installing them I just wanted to check that I'm not going to trash them in short order. The reasons for my caution are: (1)I have just measured the plate voltages in the Streamliner with reference to chassis ground, and they are: V1 206V & 209V V2 321V & 323V V3 199V & 320V (2) Max plate voltage in the [url="http://www.mif.pg.gda.pl/homepages/frank/sheets/137/1/12AX7.pdf"]Sylvania spec sheet[/url] is 300V. (3) When I first got the amp (used), V2 and V3 were out of spec according to my Orange valve tester. Does anyone have useful comments on this? Mr Foxen perhaps? EDIT for screwed up MS Word table! Edited October 18, 2013 by JapanAxe Quote Link to comment Share on other sites More sharing options...
Guest Posted October 18, 2013 Share Posted October 18, 2013 Hi Bud, I got one the same as yours from Gareth. I assume then that it will be fine in V1, that's where I was planning to fit it anyhoo. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 18, 2013 Author Share Posted October 18, 2013 Already got a JJ in V1, which has the lower plate voltages. Might try one Sylvania in V1 and the other one in my guitar amp, which has JJs throughout. Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted October 18, 2013 Share Posted October 18, 2013 Those the voltages without any valves in? It drops when you are running some. Cheapy valves sometimes start dying pretty soon, had a lot of 'working' amps where the valves don't test great. The orange tester give you any clue what was wrong? Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 19, 2013 Author Share Posted October 19, 2013 [quote name='Mr. Foxen' timestamp='1382138681' post='2248695'] Those the voltages without any valves in? It drops when you are running some. Cheapy valves sometimes start dying pretty soon, had a lot of 'working' amps where the valves don't test great. The orange tester give you any clue what was wrong? [/quote] Those were the voltages with valves in place (and warmed up), input muted. There appears to be no 'standby' mode in the sense of turning the HT off. The Orange tester gave the following matching values on Orange's proprietary scale: V1 (JJ) GOOD 11 & 13 V2 (Ruby) FAIL 3 & 14 V3 (Ruby) FAIL 8 & 14 It doesn't tell you why they've failed, but there is a list of all the tests it does [url="http://www.orangeamps.com/products/accessories/amplifier-management/vt1000/"]here[/url]. V2 scored a matching value of 3 (on a scale of 1 to 15) which Orange rate as WORN, so I guess V3 must have failed on something else. Although on one hand it wouldn't help to know the failure mode (as obviously you can't fix a broken valve!), on the other it might help to diagnose an amp fault. Genz-Benz's [url="http://www.genzbenz.com/?fa=detail&mid=2663&sid=675&cid=95"]online blurb[/url] describes the pre-amp as '300 volt' but that could just be a round figure to impress potential buyers! Actually I think I'll email them.Watch this space! Quote Link to comment Share on other sites More sharing options...
Guest Posted October 19, 2013 Share Posted October 19, 2013 What about PM'ing Aged Horse on TB. You might get a quicker response rather than waiting for Fender to get back to you. I had cause to email them over my recent STM900 purchase and waited nearly a week. Just thinking out loud ........ Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 19, 2013 Author Share Posted October 19, 2013 [quote name='Mr. Foxen' timestamp='1382138681' post='2248695'] had a lot of 'working' amps where the valves don't test great. [/quote] Yes the amp was working before I swapped the valves. [quote name='kennyrodg' timestamp='1382173890' post='2248853'] What about PM'ing Aged Horse on TB. You might get a quicker response rather than waiting for Fender to get back to you. I had cause to email them over my recent STM900 purchase and waited nearly a week. Just thinking out loud ........ [/quote] I'm not on Talkbass! Quote Link to comment Share on other sites More sharing options...
paul_5 Posted October 19, 2013 Share Posted October 19, 2013 Or give Derek at Watford Valves a call - I seriously doubt that there's nothing he doesn't know about valves. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 20, 2013 Author Share Posted October 20, 2013 (edited) I have just re-tested the old Peavey valves that I used in V2 and V3 positions. The 'before' test was after a long working life in the front end of a Peavey Duel; the 'after' test was following some home use, a jam, and a gig in the Streamliner. The figures are Orange's 'matching values': V2 before 9/9 GOOD - after 9/15 FAIL V3 before 8/10 GOOD - after 8/15 FAIL The Orange manual states: 'if two matching values are apart by more than 6 values the VT1000 will fail the valve', so that [i]could[/i] be the only reason. Bizarrely, the matching value (basically an indicator of the gain) of triode B in each valve has [i]increased[/i] after use in the Streamliner. So is the Streamliner messing with the valves? And is excessive plate voltage the reason? The valves still work, as did the Ruby Tubes that I took out from those positions. Looking back at their matching values, one triode is definitely below par (score 3) and both pairs are 6 or more apart in value, which the Orange would class as a fail. Now I'm thoroughly confused! Although I carry spare valves, I don't want to have a mid-gig fail for obvious reasons, especially if it's preventable. I'll wait and see what Genz Benz (i.e. Fender) say, but in the meantime any more words of wisdom on this thread will be appreciated! Edited October 20, 2013 by JapanAxe Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 22, 2013 Author Share Posted October 22, 2013 (edited) [i][color=#0000cd][b][size=8]D'oh![/size][/b][/color][/i] What a doofus! The figures I quoted at the start of the thread were measured against chassis ground, but what [i]really[/i] matters is the potential difference between the plate and the cathode. I actually measured the PD between the cathode and ground when I first took my readings. Subtracting these, I find the plate-to-cathode PDs are all in the range 197V-212V, well within the recommended and design maxima (300V and 330V as far as I can tell). I also got a very prompt email reply from Fender, who kindly sent me the schematics for the pre-amp board and the back panel PSU. The latter is a completely conventional step-down transformer, followed by a full-wave rectifier and a simple LP filter for smoothing. The output of this is marked as 315V DC, but that is with a primary voltage of 230V AC. UK mains voltage is required by law to be 230V (+10%/-6%), i.e. 216V-253V. It is typically 240V, and I measured ours (with the same uncalibrated meter) as 242V. Therefore the nominal 315V DC supply should actually be 315V*242V/230V = 331.4V. I measured it and got a reading of 336V, only 1% difference! Genz-Benz will have been well aware of these tolerances when designing for the various markets. So - I am no longer worried that the amp is frying my tubes. However, I do wonder why the change in performance of the old Peavey tubes. It could well be that (a) they are cheapos, and ( they had an easier life before I put them in the Streamliner. EDIT: It appears that the letter b followed by a closing parenthesis is interpreted as an emoticon! Next step will be to fit a NOS Sylvania in V1, then try JJs in V2 and V3. I will be monitoring their condition closely, and this brings me to my final observation, one I am reluctant to make after dropping £349 to own it - [i]the Orange valve tester might not be all that![/i] Edited October 22, 2013 by JapanAxe Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted October 22, 2013 Share Posted October 22, 2013 [quote name='JapanAxe' timestamp='1382470579' post='2252628'] Next step will be to fit a NOS Sylvania in V1, then try JJs in V2 and V3. I will be monitoring their condition closely, and this brings me to my final observation, one I am reluctant to make after dropping £349 to own it - [i]the Orange valve tester might not be all that![/i] [/quote] If you are Bristol way, can come try them in my tester with actual buttons and levers and suchlike. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 23, 2013 Author Share Posted October 23, 2013 [quote name='Mr. Foxen' timestamp='1382480660' post='2252819'] If you are Bristol way, can come try them in my tester with actual buttons and levers and suchlike. [/quote] Thank you kindly Mr F, I may well take you up on that! Quote Link to comment Share on other sites More sharing options...
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