I have greatly reduced the 6V6 tubes' microphonics by adding these high temperature silicone rubber o-rings. There are places on line that sell the exact same "damping" rings for $5 each. I got these from McMaster-Carr... package of 10 for $6.69
And even if they had no effect at reducing microphonics at all, those red rubber O-rings look just plain cool. Well worth the 5 bucks!!
Raising an old thread of mine from the dead (I can do that, right?)
Sitting at breakfast Saturday morning in Ankeny, IA with some friends of mine I stated that I was done building tube projects. I even offered to sell my stuff to Bill. After seeing Ani's "new toy" thread and digging through my tube stock I got bit by the tube bug yet again and decided to revisit this 6V6 tube preamp project. I never was really happy with the overall sound of this preamp. The first try was a simple grounded cathode topology that had WAY to much gain and was terribly microphonic. The next rewire was a cathode follower circuit that has zero gain, still somewhat microphonic, but no dynamic "sound" at all.
Anyone who has built a tube project knows that the largest amount of labor and cost of building these tube projects is making a nice looking hardwood case and top plate, and the parts for the power supply (power transformers and high voltage caps get pricey).
Guess what, I already have a nice looking finished case and top plate, and a very well filtered power supply. So my next step is to try another tube type and circuit topology. Probably something like the 6SN7 tube in a CCDA circuit. There is no deadline for this project. I don't have any NOS 6SN7 tubes in my stock. I'll probably buy some cheap chinese or russian tubes to play with first. I'll try to update the project when I make any progress.
I have read good things about the Aikido linestage. I'm pretty sure that uses the 6SN7 and other close cousin octals. Let me know if you need anything.
Tom, My very first project with tubes was an Aikido cathode follower preamp, using 6DJ8's that you were kind enough to gift me in that care package you sent about 9 years ago. It has been in my system continuously for that long because it sounds so good. I direct copied the main circuit topology from TubeCad's website then scratch designed my own tube rectified power supply. That's why I was asking if you had anymore NOS 6DJ8's
Ahhh - either I didn't know or had forgotten you had built that design. My memory sure isn't my strongest asset these days! I'm guessing the Aikido is a better linestage than my little SRPP 6BH7. I might have to build one for myself now.
9 years ago? Has it been that long? Man, time flies! I do have a bunch of those 6DJ8s - not NOS, but they tested fine. Do you need a quad?
Good to hear. Look forward to seeing more of your excellent point to point wiring technique. Now that you are back into tubes, you will have give your industrial TV-7 the "self-calibration" treatment. Which reminds me, I still have to "self-calibrate" my Heath-Kit TT1. Then I can start running up matched pairs of power output tubes taking actual transconductance (gm) measurements, and comparing them to the published figures in the RCA receiving tube manuals.
I've decided to add a small 12.6 volt filament transformer to this project so that I can use 12SN7 and 12SX7 tubes instead of the 6 volt 6SN7 tubes. Cost wise the 12 volt filament tubes are a fraction of the cost for NOS tubes. Like $6 per tube vs $50 to the moon!
Craig - Do you just need a pair of 6SN7's? $50 is ridiculous! There are tons of NOS 6SN7s around. Somebody is seriously hyping these things up just to raise prices. I can sure send you a few of those. Heck, I have a small stack of NOS on the shelf right next me. If you want 12SN7s, I'm pretty sure I have a few of those, but they might not be cosmetic matches.
I think you need a tube care package - xSN7s & 6DJ8s! I'll see if I still have your address.
I started reading that CCDA article. Interesting stuff - I might be able to convert my little VTV 6SN7 linestage to that topology. I'll have to see if I can get a B+ of 200v with the PT on that chassis. I never loved the VTV circuit - at least not my build of it.
Comments
And even if they had no effect at reducing microphonics at all, those red rubber O-rings look just plain cool.
Sitting at breakfast Saturday morning in Ankeny, IA with some friends of mine I stated that I was done building tube projects. I even offered to sell my stuff to Bill. After seeing Ani's "new toy" thread and digging through my tube stock I got bit by the tube bug yet again and decided to revisit this 6V6 tube preamp project. I never was really happy with the overall sound of this preamp. The first try was a simple grounded cathode topology that had WAY to much gain and was terribly microphonic. The next rewire was a cathode follower circuit that has zero gain, still somewhat microphonic, but no dynamic "sound" at all.
Anyone who has built a tube project knows that the largest amount of labor and cost of building these tube projects is making a nice looking hardwood case and top plate, and the parts for the power supply (power transformers and high voltage caps get pricey).
Guess what, I already have a nice looking finished case and top plate, and a very well filtered power supply. So my next step is to try another tube type and circuit topology. Probably something like the 6SN7 tube in a CCDA circuit. There is no deadline for this project. I don't have any NOS 6SN7 tubes in my stock. I'll probably buy some cheap chinese or russian tubes to play with first. I'll try to update the project when I make any progress.
I have read good things about the Aikido linestage. I'm pretty sure that uses the 6SN7 and other close cousin octals. Let me know if you need anything.
My very first project with tubes was an Aikido cathode follower preamp, using 6DJ8's that you were kind enough to gift me in that care package you sent about 9 years ago. It has been in my system continuously for that long because it sounds so good. I direct copied the main circuit topology from TubeCad's website then scratch designed my own tube rectified power supply. That's why I was asking if you had anymore NOS 6DJ8's
9 years ago? Has it been that long? Man, time flies! I do have a bunch of those 6DJ8s - not NOS, but they tested fine. Do you need a quad?
I think you need a tube care package - xSN7s & 6DJ8s! I'll see if I still have your address.
I started reading that CCDA article. Interesting stuff - I might be able to convert my little VTV 6SN7 linestage to that topology. I'll have to see if I can get a B+ of 200v with the PT on that chassis. I never loved the VTV circuit - at least not my build of it.
any details on these or opinions?