Ef86 Rocket

[Clyde]

Here's a few shots of my latest baby, a take on the Rocket and AC30,
normal channel EF86 sans tone control, top boost channel has the first triode running parallel. MM power TX 280-0-280 and choke, Moose's OPT. The amp wouldn't "settle" until I changed the OPT and now sounds spectacular through a Weber Blue Dog alnico and Silver Bell ceramic, gone first audition.
http://www3.telus.net/bgill1/IMG_3093.JPG

[M Fowler]

Looking good clyde, Made in Canda, aye, nice. Those boards would come in handy for some builds but that yellow get to me.
Now you said no tone control for EF86? Any problems with noise with EF86?

Mark

[soma_hero]

what did you change to OPT to?

[Clyde]

Hi Mark,
That's right, no tone controls, just the presence (cut). By judicious use of bypass cap, amongst others, you can shape the tone and it's super fat and thick. I did use a 100pf cap on the volume control for a little added sparkle and straight on into the PI.
Soma, the OPT was originally an MM AC30 clone and the amp never quite had it. With the upped impedance of the Toneslut, it's all cool. Thanks for your interest, great bunch here. Oh, and no noise with the (almost) NOS
winged C EF86. I have a handful of Mullards but....

[Structo]

Interesting build.

How is the noise factor.
I notice you tied your preamp buss wire to your power supply ground.

Do you get much buzz?

[Clyde]

There is no buzz or noise. I've developed this grounding system over numerous builds and had very good luck with it. Essentially grounding starts with the jack and increases in current flow down the line, ending with PT CT
and 1st power supply cap grounded together and in this case, power tube cathode resistor-I cheated a bit on second and third cap as you can see, got away lucky.

[M Fowler]

Clyde,

I've seen that type of grounding on 18watt.com and the guy had no issues either. Not sure why I asked about noise with the EF86 since my Stangray is also EF86 and as quiet as a church mouse. But there has been a lot of talk lately about noise with these tubes.

Mark

[jumpbluesdude]

I have read about that also. I think it is more of a persistant rattle that people have complained about with those - almost microphonic, but different. I have been curious to give them a try, but have been put off because of those complaints. Good to know that there are some sucessful builds with them also. Makes me more willing to give it a try.

[briane]

I've had a lot of experience with the ef86.

Yes, they can go microphonic, and a large percentage do. The quality of tubes seems a lot more unreliable than in the 12ax7 world.

Apparently the microphonic issues can be alleviated by
1) shrink wrapping or suspension mounting the tube socket
2) a good solid long warm up time the first time turned on (say an hour). This allows the parts to expand, rather than going through a repeated expand/compression prior to the first large expansion.

I dont suspension mount, do shrink wrap or use tube grommets, and have an extended first time warm up period. I've been told a suspension mount willl get you around all issues.

its a great tube, lottsa different than 12ax7. Should give it a try. For me this was a critical aspect of my SSS derivative clone.

That said due to is dicey characteristics, would never use an ef86 where a 12ax7 would do, but for clean tones the 12ax always has a bit of grit compared to the ef86.

[M Fowler]

Braine are you going to help us with our quest to build some SSS now that we have face plates and chassis done?
Not much out there on building the SSS.

https://tubeamparchive.com/viewtopic.php?t=7972

Mark

[Clyde]

I do suspension mounts-rubber o-rings between socket and chassis and screw head and socket.

[briane]

Braine are you going to help us with our quest to build some SSS now that we have face plates and chassis done?
Not much out there on building the SSS.

Well my take is the SSS is a quest, not a build. I spent almost 2 years ripping apart circuits before I was happy. its known that the SSS had many derivatives, I think one of the biggest questions to answer first is what is your approach, and specifically what tube compliment/path you wish to follow. I put a bunch of details in that clean monster thread.

for me, ef86 & 12ax7 paralleled (for clean), moded dumbleator for drive channel, dual 12ax7 pi, aka simple svt style, and dual 6550.

I've figured out the filters (mostly) though not the values (yet). Though have not put them in.

You cant shoot me a pm, but it really is a journey, and you just cant farm out the battle wounds.

[Normster]

...it really is a journey, and you just cant farm out the battle wounds.

Amen to that!