EF86s Are Weird | Amp Design & Pricing Considerations

[@shanedolman1368]

I love the sound of an EF86 but they are so problematic nowadays and that's what made me switch to cascodes. Yes I know they dont sound quite the same but they give a flavour, besides I have a stick of mullard E88CC! Lyle dont know about you thanking us for watching, as far as I'm concerned it's a privilege and an utter pleasure to be allowed to watch your progress with this amp design just as it is with all your videos. Thank you sir👍😀

[@mikeh892]

I've got a whole handful of 12au7s in the stash. Gotta try the cascode thing.

[@shanedolman1368]

@@mikeh892 I use the grid leak biased version it gives some of the screen compression effect you see in pentodes.

[@jasonstone1046]

Loving the detailed chime on that baby. Beautiful.

[@TheAxe4Ever]

Bro. That’s not being snobbish, elitist or egotistical. That’s just making sure something is right. Dear old dad always told me any job you do is worth doing right. There is correct and there’s incorrect. There is no “good enough”. Always strive for “correct”. That shows you care about your work AND your future customers. Keep up the great work! By the way, you mentioned Ceriatone. What are your thoughts on those amps? I almost pulled the trigger on one. That is until I saw you are designing amps. I figured I’ll just wait.

[@Satchmoeddie]

Backorders are killing me on EVERYTHING from guitar parts, to car parts to amp parts etc.

[@chokkan7]

You have a long row to hoe, but you're correct in sourcing from Japan wherever possible; their attention to detail is unrivaled. I lived there for over a decade some time back, and I still have boxes of parts (tubes, tantalum resistors, etc.) from weekend trips to the flea markets in Akihabara. My wife went back for a visit last year, and I gave her a wish list; she returned with two beautiful 12AX7s and the news that the flea market is now one small stall...

[@OpSic66]

I've been an electronics tinkering person for over a decade. I hear you all on this. I've got a few items that were on my bench, that have now moved into storage bins as the items I've got ordered for them, have been on back order since January 2021!

[@LPCustom3]

Having had EF86 amps over the years(Vox mainly). The old Mullard’s with the screen inside sounds the best!

[@matthewf1979]

Best of luck with the parts shortage! Losing Classictone still hurts me.

[@chipsterb4946]

I know what you mean. A good source for transformers no doubt.

[@leiferickson3183]

Yeah that one was bad.

[@mattjohnson6916]

Ditto... I've got one PT and one OT by them left for my Bassman build, then I'll have to decide on what manufacturer to go with for some future stuff I have in the works. :(

[@kbkman7742]

What's everyone's thoughts on Hammond? Those are available where I live, they seem to make a transformer for just about every fender I could think of. I am shopping for a new bassman pt at the moment. The only issue I seem to find searching on the net is high filament voltage

[@chipsterb4946]

@@mattjohnson6916 I completely forgot a PT/OT set from ClassicTone that’s supposed to go into a single ended build some day 😜. They’re around here somewhere… along with the schematic and a partial layout.

[@averagenetfool]

The old Akai M8 tape recorder amp has a separate 5.7 volt filament winding for the 6267 tube. It seems even in the old days, the 6267 needed special treatment.

[@williambock1821]

I just got 2 Akai M8’s 4 amps altogether. Probably gonna make them into AC-4’s since everything is pretty rough looking inside. Hopefully the transformers and tubes are ok. Glad I noticed your comment! I haven’t started excavation yet.

[@onewireman]

Thank you for your wonderful channel. I have a beautiful pair of NOS EF86 Amperex tubes in the box I'll never use. Will gladly gift (UPS) them to you.

[@PsionicAudio]

I appreciate that, but that would be a $200 gift. I can't accept that. Very kind of you to offer, but sell those bad boys!

[@oldguy5381]

Ahh, consistency that’s a balancing act worthy of the Ed Sullivan show. There that dates me. Good luck

[@TheAxe4Ever]

Well, wasn’t it Ed Sullivan that said “If you do a good job for others, you heal yourself at the same time, because a dose of joy is a spiritual cure. It transcends all barriers.”

[@oldguy5381]

@@TheAxe4Ever not sure if that’s so, but I do remember a crazy man spinning plates on a stick. 😂

[@benlogan430]

It’s almost impossible to run a business these days. You can’t get a reliable supply chain for anything lately. Prices are up and down and the labor market is the same. Good luck with this sweet product!

[@Jonathan_Doe_]

US made subminiature valves sound fantastic, and there’s a huge NOS supply due to the military demand at the time (The Sylvania’s are rated for 80’000 feet!). 6021’s sound good but obviously you’d probably need two to get pentode levels of gain.

[@RodVonLongrod]

A quality amp built to high standards, using quality components, by a knowledgeable builder is worth the price.

[@sjolsen]

I doubt this will be much help at this point and I'm no expert on the subject to begin with, but it's an interesting problem and I figure what the hell, might as well share my thought process. The AC15 EF86 circuit (or what's being presented as such online) already derives the screen current from the DC component of the anode current. Ideally that would be enough to establish a fixed ratio, but I'm guessing the source impedance presented by the 1M resistor is just too high to accommodate tube variations. That 1M is important though, because it prevents the screen from dragging down the plate voltage. What do you use when you need to connect a high-impedance source to a low-impedance load? An amplifier! There are a couple of ways to do this depending on whether you want a fixed voltage or current ratio, but I think the simplest is this: remove the 1M resistor and connect the gate of a suitably rated P-channel FET to the low side of the 22k anode resistor (call that Ra). Connect the drain to the screen and connect the source to B+ through a resistor (Rs). Taken as a source follower, this sets the voltage across Rs equal to the voltage across Ra (ignoring Vgs), which makes the screen current proportional to the plate current with ratio Ra/Rs. Does this circuit work? Does it sound right? Will it turn a perfectly good amplifier into a makeshift fireworks display? Your guess is as good as mine.

[@Tecniconta]

El VOX AC15 tiene dos tubos EL84, creo que el antiguo VOX tenía dos EF86, encontré este juego de esos tubos 2 X EF86 MULLARD TUBE. Década de 1960 MAZDA PROD. MESH PLATE, ¿crees que marcaría una gran diferencia en el tono? porque como es de stock no me gusta y estoy pensando en venderlo

[@LosFicosMusic]

Still making boxes? I need a Amp 2 EF86’s. Two inputs two outs (LiNE) and can you throw in a tube mix/dry knob?

[@simonkormendy849]

I've read online that the EF86 has some reliability issues when used in guitar amps.

[@edwardhannigan6324]

Nice Lyle, what an amp..!

[@dan_perry]

Considering the variations between current production and NOS EF86's, I think that I might of added some trimmers to that stage just to dial it in perfectly. Edit: That might be to much to ask of a end user...umm, maybe a zener regulated supply?

[@kengevers8738]

Lyle, have you ever tried the 5879? You may be pleasantly surprised. 😀

[@PsionicAudio]

Many times. It's a backup plan for this, in case reliable EF96s get more difficult to source. Notice the front panel says Pentode. Not EF86.

[@MarySmith-bw5xm]

V1 in se Amp bias hotter than Gibson circuit

[@stevehead365]

If the (modern) EF86 proves intractable there is the SRPP circuit www.tubecad.com/may2000/page1.html. I have been experimenting with a fixed bias JFET version and the bias can easily be set for even clipping or not, as you wish. A 12AX7 SRPP would probably not give as much gain as an EF86. Excellent build, one of the best I have seen. I hope you resolve the modern EF86 issues. Steve.

[@BenState]

Hey Lyle, do you ever go to the trouble to test capacitors before installation for polarity?

[@David.S.]

what's your opinion on dampers (e.g. rubber o-rings, shock mount socket) for the ef86, necessary? I saw a video of someone wrapping the entire ef86 in a rubber sheet, and holding it with a hose clamp. Seems a little excessive..

[@PsionicAudio]

Maybe o-rings help a little. Don't pay audiofool prices for them - most car supply places sell .75" high temp silicon o-rings for very little money. I shock mount the sockets which definitely helps.

[@tedmich]

Have 6 stacked turret boards, one for each current EF86 available, and switch between them! Where did I see that 48P6T rotary switch?

[@vernonchelski7385]

There's a lot of NOS subminiature tubes available including pentodes. Maybe there's some that sound like a NOS EF86. Look what you can do with subminis. od.lk/s/OV8xODgyMTQxOTFf/Raytheon-dual-triode.JPG od.lk/s/OV8xODgyMTQyNzNf/submini-c.jpg BTW, My favorite 6267 was National brand (made in USSR). I used the 6267 in a stereo phono preamp.

[@JR-to8sn]

Have your ever tried the EF806S? Thoughts?

[@markarita3]

V1 pin 9, just curious...why is all that outer jacket missing? That's REALLY not your style. I'm guessing there's a very valid reason...sounds awesome btw.

[@PsionicAudio]

Because there is nothing noisy next to it and it slightly decreases the weight/pressure on the pin (which can make the EF86 mechanically less rigid/prone to microphonics). IOW, it's fine.

[@chipsterb4946]

It may be that current production “EF86s” are too different from old stock, similar to current 5Y3GT rectifiers which aren’t the same tube at all. That new tube doesn’t sound as good as the NOS EF86. Not bad, but you had the NOS tube singing.

[@ajhnubia]

The EF86 is a low noise pentode my 1958 Quad amp uses them in the power amp inputs. They were also used in tape recorders but I would say its not all that good for guitar amps. When designing amps you must be aware of ageing, thus biasing etc must be set to alow for 50% reduction in gain, other wise you will be replacing valves every year

[@antonix_81]

is the 6j32p any good? i would like to try it, some says it's horrible...

[@edwardcarbonaro8920]

This means that you are going out of the repair business?

[@r.weaver3769]

Off subject, sorta, you mentioned a better sounding EL34 than JJs, what might those be?

[@PsionicAudio]

Of current production 34s I like Mullard RIs.

[@Satchmoeddie]

JJ makes an EF86, and Electro-Harmonix also makes an EF86. Those are the two modern production choices available right now. I have Mullard UK, Brimar UK, Tesla Czechoslovakia (NOT JJ), Tungsram Hungary, Telefunken W German and Philips Amperex Holland, EF86s, but I very much prefer to use JJs or Electrohrmonix so the customers can easily find replacement tubes.

[@PsionicAudio]

I forgot about JJ because they name it slightly differently.

[@Satchmoeddie]

@@PsionicAudio EF806.

[@Satchmoeddie]

Like it's a German made Telefunken. (rolling my eyes)

[@Satchmoeddie]

The old Winged C Svetlana Soviet (St Petersburg not Saratov) EF86s were not too bad, and 12 or 15 years ago they were pretty darned cheap too. The plates were made with a matrix of tiny pyramids with a dimple in the middle each one making the plates very rigid and somewhat more resistant to becoming microphonic. The Chinese copied that Winged C EF86 tube under ?? brand. (Shugrang?) Not nearly as well made. An extremely poor attempt was made at copying that plate structure. I need to unearth my 1984 Soviet vacuum tube book. (With a forward by George Orwell)

[@garretthead]

If the modern "ef86" doesn't operate with the characteristics of actual ef86 tubes, it just isn't an ef86... What you describe is a radically different operating point...

[@JR-to8sn]

Current EF86's production these days don't meet spec, in fact I don't think any of the new tubes meet original specs. Based on the costs of the new production tubes, I buy a few NOS/pulled tubes that meet spec, built better and will last a lot longer. New tubes work fine, but I just don't think they're all that great.

[@edwardcarbonaro8920]

Wish all amplifier came with a voltage conditioner, no matter what ac in amp gets constance voltage in without having to have a external conditioner

[@jonathanhorne6503]

I have Atleast a half dozen various brands I’d loan out to you. Seimens, RFT, real Tesla, Mullards etc. no Telefunkens.

[@estring69]

Amazing how that death star tremolo Vox turned into a nice 2 acre plot neighborhood without the trem circuits.

[@Burgschall]

That will be a real puristic killer amp...

[@richardlynch5632]

😎👍❤🖖

[@vucinicbozo]

Ei Yugoslavia, also

[@elwrongo]

Not bad? I thought it sounded aces. Great breakup.

[@MarySmith-bw5xm]

5879 much better.v1 in 2 of my se kt66 amps .Gibson circuit but cathode resistor value in half

[@SGspecial84]

holy salesman alert.

[@ebeep]

I'm gonna say it: EF86 isn't worth the trouble.

[@PsionicAudio]

Ok. But I'm at least showing people what you mean by "trouble." ;)

[@MarySmith-bw5xm]

Been there

[@simonkormendy849]

I've read online that the EF86 has some reliability issues when used in guitar amps.