Quote:
Originally Posted by Cableguy
Thanks for the info sacdlover. Interesting choice of output tubes. The same tubes are used for output in my Modwright Sony 999es. What made you decide on these and do you think the sound signature would be similar to the 6922's? Thanks.
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The answer starts with the high cost of 6sn7's in my singlepower mpx3. I much prefer the sound of the better nos tubes but I cant afford nor routinely find the ones I wanted. Therefore, I started looking for high quality but low cost alternatives. I set up a criteria of focusing on sound quality, availability, reliability and low cost. The first tube I settled on.... the 12sn7, was a home run. I am getting the best 6sn7 equivalents for pennies on the dollar charged for 6sn7's. The 12sn7 is the identical tube it just uses a different heater voltage.
Now curious, I started researching other tubes and came upon 7n7's, 5687's and another tube I dont want to mention yet (until I get my lifetime supply). The 5687 is inexpensive (I bought many of mine for <$4-7), available, highly reliable, (being a military tube designed to operate in stessful environments) and the tube sounds very,very good. The 5687 is also a very high output tube, being capable of up to 2.5x the peak output of a 6sn7; making it highly desireable as an output tube for headphone applications.
I then managed to talk Mikhail into building me an amp using the 5687 as the output tubes. I ended up using a 6cg7 as the driver because I needed the tube sockets to be the same size as the 9 pin mini sockets the 5687 uses. I originally wanted to use a 12sn7 for gain because th 5687's can be wired to run with a 12 volt heater. But this would have required a custom chassis, a 12 volt transformer etc. so I went with the 6cg7 and the standard ppx3 chassis. Fortunately,the 6cg7 pairing with the 5687 was another home run. The 6cg7/5687 combination is more open and dimensional with an extremely powerful bass register. I always liked the ppx3-6cg7 but this tube combo is much better to me.
As for your question about the 6922, I like the 6cg7/ 5687 much better than the 6922's(or 6bz7/6dj8) driving a 6as7 in my Woo 3. The 5687 used as the output tubes sounds nothing like the 6922 used as an input/gain tube. Whats hard to say is what each tube really sounds like on its own, since they are mated to another tube to complete the amplification chain.
Now... I couldnt resist, so I picked up a mpx3-6cg7 and I am modding the amp to use all 5687's, so I will know about the 5687. I have high expectations because the 5687 added a good amount of openess and dimensionality to the 6cg7/ 5687. The tube is clean, clear and very powerful sounding. The 6cg7/5687 amp has so much more control than the standard ppx3. This amp starts and stops like my tube rectified supra 6cg7 and the mid-bass is awesome. I guess you can tell I am a big fan of this tube.
) to build me a ppx3 type amp with 5687 outputs for some time. Once he built mine, he liked it so well, he decided to do a production version. The SLAM is going to be debuting at the upcoming Maryland meet from my understanding. I know the prototype/ production version will be a little different than my amp. He probably just hasnt had time to update his website.
