Converting tube types.
Apr 22, 2013 at 11:10 AM Thread Starter Post #1 of 36

ilikepooters

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Yes i've ordered some tubes which are incompatible with my Lyr and i want to figure out how to convert them into compatible ones 
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Basically i've ordered some E80CC's which are both 12v and 6v, the problem is with one of the pins, pin 9 on the E80CC is HCT (heater center tap), whereas pin 9 on ECC88/E88CC and it's analogues is a ground for the shield.
 
Any way i can modify some cheap chinese socket savers to use E80CC in place of ECC88? I'm aware of the greater heater current demand and that's a non-issue, just want to get these pin-compatible.
 
Apr 22, 2013 at 4:02 PM Post #3 of 36

nikongod

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Why not just return them? 
 
No, it is not as simple as cutting off a pin. At a minimum you need to make an adapter socket thingy. I have not checked the datasheet, so that may not even work.
 
Apr 22, 2013 at 4:10 PM Post #4 of 36

ilikepooters

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Apr 22, 2013 at 4:34 PM Post #5 of 36

nikongod

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Quote:
E80CC data sheet: http://www.r-type.org/pdfs/e80cc.pdf
E88CC data sheet for comparison: http://www.r-type.org/pdfs/e88cc.pdf
 
Ideally i'd like to find a way to get them working because E80CC are a super high-end tube, great for audio.

 
e88cc is a super high end tube too.
 
Which is better? 
This is an interesting question, and IME the sound you get from a given tube depends as much on the circuit its in as the actual tube. If you get really lucky you find designs that only work with specific samples of 6sn7, where other amps work great with the 6sn7 you cant use. 
 
An "even better tube" in a circuit designed for an e80cc is probably going to sound like garbage. Considering the trends in tube audio design it will probably be a hit. 
 
Send them back. If you cant send them back design an amp around them or buy an amp to use them with. 
 
Apr 22, 2013 at 4:49 PM Post #6 of 36

dsavitsk

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Super high end tubes :rolleyes: whatever that means, does not mean that they are suitable for this circuit. Specs are not even close -- rp of the 6922 is 2K5 while the E80CC is 10K, and Gm of the 6922 is 5x higher. I don't know the circuit here, but it is almost a certainty that they will not operate in a way to justify their use.

That said, it is certainty possible that cutting the trace to one of the heater pins (4 or 5), rewiring it to connect to the CT (9), and connecting 4 and 5 together will solve the heater problem. But this is like chopping off the fender of a muscle car to fit Prius engine in -- the Prius engine is great for what it does, but it is likely not appropriate here.
 
Apr 22, 2013 at 6:13 PM Post #7 of 36

duncan1

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ILIKEPOOTERS-Those valves with a CT can be connected heater wise either in series or parallel
          For series and current halved  connection the voltage is doubled[12V] 
              DSAVITSK is right shorting pins 4/5 together and putting the other heater lead on 9 will work
                    Some systems I have come across used only one heater lead and the other earthed. If that is the case and pin9 goes to earth as a screen[on the base] you wouldnt have to remove it. 
 
Apr 22, 2013 at 6:29 PM Post #8 of 36

ilikepooters

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The way i'm going to do it is to re-wire a socket saver, so to get this straight in my head, i can wire pins 4 and 5 together and connect them to pin 4 in the socket saver so they both together become pin 4, and pin 9 i can connect to the now spare pin 5 in the socket saver?
 
Or in simpler/clearer terms, pin 4 and 5 on the tube need to share a heater lead, with pin 9 being connected to the remaining heater lead?
 
I'm very much a novice but i can use a soldering iron, so layman's terms are probably best for me 
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Even if it sounds crap at least i've learned something 
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Many thanks for everyones input, it's really very appreciated 
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Apr 23, 2013 at 7:22 AM Post #10 of 36

duncan1

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Nikongod has got me worried a bit-So I checked LYRS web-site the design is a tube/mos-fet hybrid  Is the heater voltage -AC or DC-I just assumed it was AC
                      If DC then you would have to make sure that the NEG. DC was attached to the earth-thats pre supposing the heater voltage isnt "floating" but referenced to earth.               I didnt know you were a novice -your second paragraph is correct in simpler terms.
                          If it is DC---be careful ---very careful! you could blow something. 
                             Have you a link to a circuit diagram?
 
Apr 23, 2013 at 10:22 AM Post #12 of 36

duncan1

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Settle down! I was talking about your post made me think of the above problems that could occur. NOT I am worried by you.Look at it positively.
             I am NOT disagreeing with you  in the sense that what he is doing is "the right way" to go about it.
                But if he had sufficient Technical knowledge  he could make the changes to make the tubes work in his amp.
                     I fully realize that this would be against the manufacturers advice / but look how many modified amps appear on Head-FI-
                        1000s.   If it were not feasible and totally wrong from a DIY point of view then okay but you don't want to put everybody off that is trying to advance their knowledge of audio electronics. 
 
Apr 24, 2013 at 8:21 AM Post #13 of 36

duncan1

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Audio tubes make up only a small part of the tube range . IN tube radio repair there are literally 10000s of types worldwide.  
                    From the early radio era of the 20 s onwards both Europe and the US made their own types and bases many non-compatible with each other in terms of bases.
                         I have converted 100s of tube bases because the tubes that were low  emission were obsolete.
                           for later ones that were approx the same spec. changing maybe the cathode bias resistor or plate feed resistor/screen grid resistor.
                              to make it operate correctly under the same conditions .
                                  Your "tube rolling" doesn't mention changing any of those even though many audio tubes wont perform at their peak unless those are changed.
                                      Tubes aren't "universal" would you put a Ford part into a GMC truck?
                                          So all those tubes will behave differently when plugged into a tube base that was designed for another tube.
                                             Please note-- I am talking about electrical compatibility NOT the different tube base connections.
                                                Using the old tube--- [not all glass construction of more modern ones] smash the glass and using  the bottom
                                                     solder thick copper wire into the pins --attach to new  tube base -plug new tube into that base--That's how it was done before the era of
                                                       commercially  available  converters.
                                                          I did the same to my tube tester for newer type tubes. 
 
Apr 25, 2013 at 5:52 AM Post #14 of 36

ilikepooters

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I can confirm Lyr is 6.3v AC, tested with multi-meter.
 
So just to clarify, i need to wire heater pins 4 and 5 on the tube together, and connect to either 4 or 5 in the socket, lets say i choose 4, then i need to connect pin 9 (heater center tap) to the remaining pin 5 in the socket.
 
And this would have the tube heaters running in parallel at 6.3v?
 
I am aware of other parameters being different, like anode voltage is 250v in E80CC vs 100v in E88CC, but i'm currently using ECC85 which is also 250v and they're the best tubes i've ever heard in Lyr, they're closer in spec to E80CC than they are to E88CC, ECC85 are my best sounding tubes by far.
 
For now i'm wanting to learn how to get them pin compatible with Lyr so i don't blow it up before i complicate things with other parameters.
 
Everyone's gotta learn somewhere right? And i'm hoping i'm being responsible by seeking guidance as i do things instead of leaping in feet first and blowing Schiit up (pun intended)
 
I do plan on doing a whole lot of reading as well as building many hobby kits to get a better understanding of electronics, in the end i'm hoping to build my own headphone amp and possibly even a DAC, would give me a real sense of achievement.
 
Many thanks for everyones input, you are wonderful guys 
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Apr 25, 2013 at 6:42 AM Post #15 of 36

duncan1

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That simplifies it if it is 6.3 AC-Just remove  the connection on the base thats connected to pin 9-as It will probably be connected to earth as it is designated screen[protection from radiated interference] and exactly as you say--4+5 TOGETHER--ONE HEATER LEAD---9-the OTHER HEATER LEAD.
                 Your also right[imo] that the ECC85 is a good tube- The ones with the CC at the end were specified  for government/armed forces etc use-some having higher gain etc. were called SQ[special quality]-
                     And you are right again -wired like this they run in PARALLEL -series-12 V. You can actually run only one triode at a time by feeding either 4 or 5 singly.    
 

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