BATMAQN Posted November 15, 2019 Share Posted November 15, 2019 Hi guys Noob query sorry Have some tubes that I got spare with an amp I bought ages ago they have the same bottom plate configuration as an EL34 but they are missing 2 pins not damaged they are all the same, anyone please? Cheers Link to comment Share on other sites More sharing options...
klackto Posted November 15, 2019 Share Posted November 15, 2019 Rectifiers? Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 15, 2019 Share Posted November 15, 2019 Maybe if you post some pics of said tubes it may help Link to comment Share on other sites More sharing options...
RoHo Posted November 15, 2019 Share Posted November 15, 2019 The EL34 uses the "octal" socket as did a bucket-load of other tubes. Sometimes unused pins were left off. Your spare tubes could be anything. Is the type number still visible anywhere on the tube? 1 Link to comment Share on other sites More sharing options...
BATMAQN Posted November 15, 2019 Author Share Posted November 15, 2019 Hi Guys Thanks for the replies I'll do some pics when I get home a bit later. Cheers Link to comment Share on other sites More sharing options...
BATMAQN Posted November 15, 2019 Author Share Posted November 15, 2019 (edited) Ok so here are some pics hope they are clear enough. First 2 are the ones I’m asking about I think this one is from a guitar amp. second 2 are the 6CA7 cheers Actually the photos didn't load as I thought the 2 middle photos go together Edited November 15, 2019 by BATMAQN Link to comment Share on other sites More sharing options...
BATMAQN Posted November 15, 2019 Author Share Posted November 15, 2019 The EL34 Mullards also have a pin missing I'm presuming now that this is normal practise depending on the type of tube. I presume most valve amps if they use the octet valve seat should be fine with these varying tube pins bit noobish I know but oh well. Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 16, 2019 Share Posted November 16, 2019 (edited) @BATMAQNThey are marked with what tubes they are. The first can't see due to the pic, but the designation is there on the EH tube. The second a Sovtek 5881, so similar to 6L6 Check the data sheets for the EH tube to check if they should only have 6 pins. Edited November 16, 2019 by Muon N' Link to comment Share on other sites More sharing options...
ophool Posted November 16, 2019 Share Posted November 16, 2019 1 hour ago, BATMAQN said: I presume most valve amps if they use the octet valve seat should be fine with these varying tube pins Not an assumption I would be prepared to make given the wide variety of valve types and pinouts using the octal arrangement. Using a pentode in place of a rectifier (or vice versa) might create more excitement than would be wanted. Even amongst the pentodes, checking the list of substitutes for the 6L6 shows many having varying pinouts which would therefore not be "drop in" replacements. From what I can find, a 5881 is a pentode that should have 7 connected pins as also is the 6L6, the EL34 is also a pentode having 7 connected pins so the missing one on your Mullards is fine. 6 pins on a 5881 does not compute. 1 Link to comment Share on other sites More sharing options...
BATMAQN Posted November 16, 2019 Author Share Posted November 16, 2019 41 minutes ago, ophool said: Not an assumption I would be prepared to make given the wide variety of valve types and pinouts using the octal arrangement. Using a pentode in place of a rectifier (or vice versa) might create more excitement than would be wanted. Even amongst the pentodes, checking the list of substitutes for the 6L6 shows many having varying pinouts which would therefore not be "drop in" replacements. From what I can find, a 5881 is a pentode that should have 7 connected pins as also is the 6L6, the EL34 is also a pentode having 7 connected pins so the missing one on your Mullards is fine. 6 pins on a 5881 does not compute. Yep I do agree hence why I put the question out I find the whole thing a bit confusing. Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 16, 2019 Share Posted November 16, 2019 1 hour ago, ophool said: 6 pins on a 5881 does not compute Yes, as it appears that the Sovtek 5881 has 7 pins in that last shot, the EH tube where we can't make out the designation in that pic seems to have 6 pins in It's second pic. Link to comment Share on other sites More sharing options...
bob_m_54 Posted November 16, 2019 Share Posted November 16, 2019 6L6GC? 1 Link to comment Share on other sites More sharing options...
ophool Posted November 16, 2019 Share Posted November 16, 2019 3 hours ago, BATMAQN said: Actually the photos didn't load as I thought the 2 middle photos go together Reading this I took pics to be (numbering from top down) 1 & 4 the EH 6CA7, 2 & 3 the Sovtek 5881/6L6WGC 1 Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 16, 2019 Share Posted November 16, 2019 3 hours ago, BATMAQN said: I presume most valve amps if they use the octet valve seat should be fine with these varying tube pins bit noobish I know but oh well. Definitely no, far from it. You need to know what the valve is, and even if pin compatible it may still not be a compatible substitute electrically. Lots of valves are octal base like these, lots of varying power tubes, some compatible some not, twin triode signal tubes of many types, and rectifiers and other tube types. Link to comment Share on other sites More sharing options...
BATMAQN Posted November 16, 2019 Author Share Posted November 16, 2019 Ok all good thanks guys I'm not messing with my amps I'm just curious about the varying pins on tubes, so what would the 6pin 5881 tube be for anyone hazard a guess? Link to comment Share on other sites More sharing options...
RoHo Posted November 16, 2019 Share Posted November 16, 2019 (edited) 1 hour ago, BATMAQN said: Ok all good thanks guys I'm not messing with my amps I'm just curious about the varying pins on tubes, so what would the 6pin 5881 tube be for anyone hazard a guess? It's just a normal 5881. See the 6L6 diagram posted above by bob. The 3rd grid is connected To the cathode inside the tube. So it has 7 "connections" but only 6 are external. That means two unused pins, one or both of these may be left out. Edited November 16, 2019 by RoHo 1 Link to comment Share on other sites More sharing options...
BATMAQN Posted November 16, 2019 Author Share Posted November 16, 2019 2 minutes ago, RoHo said: It's just a normal 5881. See the 6L6 diagram posted above by bob. The 3rd grid is connected To the cathode inside the tube. So it has 7 "connections" but only 6 are external Thank you, it's what I suspected but I'm not too up with tube knowledge trying to learn from the more experienced guys. Cheers Link to comment Share on other sites More sharing options...
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