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BATMAQN

Valve pins

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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

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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?

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Hi Guys

 

Thanks for the replies I'll do some pics when I get home a bit later.

 

Cheers

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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
 

 

BF5486E5-9AC0-4A9A-9EC5-459EE06E9945.jpeg

847BC703-3B7E-4F1D-B20A-C1DA89B42F16.jpeg

5D227097-80C3-4554-B8CA-5CE18D8C26C4.jpeg

64F24344-9ED3-44D3-BFFF-3BB2E3E337F5.jpeg

Edited by BATMAQN

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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.

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@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 by Muon N'

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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.

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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.

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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.

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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

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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.

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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?

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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 by RoHo

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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

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