Using JJ ECC99 in place of 5687 tubes
Posted 25 September 2009 - 06:14 PM
I am not knowledgeable in electronics and I would appreciate your help since I would like to use the JJ ECC99 tube in a Singlepower MPX3 as an output tube. Yes I know, Mikhail has made some horrible amps and has stolen a lot of money from many. However I already own the amp (bought it from Tyrion) and w/ Dr. Gilmore's help I replaced the diodes, verified the transformer is acceptable, and installed a couple of resistors to bleed the large power caps.
I first came across the JJ ECC99 tube in a headphone amp by Dr. Lloyd of Mapletreee Audio. Recently I read the JJ ECC99 could be used in place of the 5687 provided a base is made to properly account for the difference in pin location. I would appreciate it if someone could help me by first verifying the JJ ECC99 can indeed be used in place of the 5687. Then I would like to know if could find an interested builder so I could commission two bases to adapt the JJ ECC99 to the 6SN7 bases in the Singlepower MPX3.
Posted 25 September 2009 - 06:23 PM
Posted 25 September 2009 - 06:26 PM
Edited by luvdunhill, 25 September 2009 - 06:28 PM.
Posted 25 September 2009 - 07:37 PM
For a given bias and current, the ecc99 runs at a higher plate voltage than the 5687 -- typically ~20% higher I'd say. This means that with a fixed plate voltage, the bias and current will run lower than on the 5687. Not knowing the circuit, I have no idea if this makes any difference, but probably not.
However, 5687's are linear, plentiful, and relatively cheap, so I don't think you are gaining anything by using the other tube. I agree with Marc that I'd leave it as is and save your pennies.
Posted 26 September 2009 - 12:52 AM
As I replied you at Auriculares.org, I don't think it's a great idea to use a 5687 --worse an ECC99 which is not direct 5687 replacement-- on a circuit designed around the 6SN7 if you cannot change plate voltage, bias current and other parameters to take the tube to its specified performance. Moreover, knowing how Mikhail worked on his amps, I'm not very sure the amp will stand working flawlessly for much time if you start swapping tube types.
In any case you may wish to try a search at Ebay, there are many tube adapters over there. At this moment no 5687 to 6SN7 available, but you might contact any of the sellers (most are chinese), eventually one could make the adapter for you. Otherwise one may appear in the future.
Posted 26 September 2009 - 04:50 AM
Posted 26 September 2009 - 05:35 AM
I'd contact JJ to see if they can direct you to some manufacturer making such adapters. Good luck.
Posted 26 September 2009 - 07:29 AM
Unless Im mistaken,the ECC99 fits what singlepower called the ECC-1 adapter. Same adapter as for the 12a*7 & 12bh7
The MPX3 puts about 160V on the plate of the "bottom" triode in the WCF, which looks like a nice voltage for the ECC99 BUT! I would note that the ECC99 will draw about twice as much current as 6sn7 in an MPX3 (about 25mA vs 8-12mA depending on exactly how the amp was built) This puts you very close to the maximum plate dissipation on the ecc99. If your amp can run 6BL7/6BX7 for sure it can handle the current, but the tube will be running just short of its power limit. If your amp has the high-voltage switch DO NOT use high voltage with this tube.
imagine you were a can opener, you accidently open a can of woop ass and the next thing you know, the peas are mushed, the beans are baked, the fruit is sliced and everything gets OWNED
If you dont stir the pot from time to time the bottom burns.
Posted 26 September 2009 - 07:37 AM
According to the Hammond site ( Hammond Mfg. - Universal Primary - "Classic" Power Transformers ) the specs of the 372BX are:
600V C.T. @ 115ma.
5V C.T. @ 2A
6.3V C.T. @ 3A
The inside of the amp before I replaced the diodes looks like ...
Here is a picture of the replaced diodes ...
Does this information help in any way? Thanks.
Posted 06 October 2009 - 02:35 AM
The JJ ECC99 is a nice tube- relative to other current production tubes, that is. I have a couple of them, and also some Svetlana versions of the same. The JJ is better than the older Svetlana tubes, but the 5687 is notably sweeter.
Looks like your former bridge was working pretty hard.
Posted 06 October 2009 - 04:20 PM
voodoochile, you are correct. The diodes were burning up the board, I have since cleaned up my work and re-flowed the solder joints. They are much better now.
Posted 06 October 2009 - 05:11 PM
Thanks again guys, I am going to give it a try so I ordered tube bases and will see how it comes out. I may even post pics of my newbie work.
One thing -- these are high Gm tubes, and they can and will oscillate without some care. And, the long leads necessary to build an adapter can act as antennae. To that end, stoppers on all the pins (of the 9 pin socket), except the heaters, would be prudent. I'd maybe put 1K resistors on the grid pins, and 10 to 20 ohm resistors on the cathode and plate pins. The best resistors to use would be SMDs, but if that presents too much of a soldering challenge, some sort of carbon film or comps would be fine. Just get them as close to the tube pins as possible.
Also, keep in mind that oscillation is not necessarilly obvious -- sometimes it will just manifest itself as a bit of hardness, or glare, or jut lack of midrange clarity. Indeed, ECC99's have a reputation of being hard sounding, and I wouldn't be at all surprised if it isn't just a tendency to oscillate at HF.
Posted 07 October 2009 - 02:30 PM
Posted 17 October 2009 - 07:01 AM
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