Ef86 to 6SH7 adapter (matchless clubman

[toner]

hi, I've got a matchless clubman with EF86, the original circuit had octal 6SH7 in that spot… i was curious to try the original octal tube and want to use an adapter to try it… but i only have a 12ax7 to octal adapter… I'm not sure if the pinout of the octal adapter is the same for 12ax7 and ef86 to octal…. you think it will work with that adapter, or will it hurt to try?
thanks!
bry

[matt h]

(deleted)

[rp]

^!!!

Do not swap any tubes if you don't know what you are doing or have an ok from a tech or at minimum from someone that's gotten away with it already. But you sort of know that, which is why you are here. You could wind up with something like a plate to ground - poof. If you are lucky the fuse pops but usually it's smoke and a toasted resistor first. If you can't fix it yourself you're out $150.

It's odd people who never think of opening their disposable $20 clock radio and swapping transistors but will swap tubes in $2K amps that have a $100 bench charge. I guess 'cause you can easily swap tubes people think they are all interchangeable. Wonder if peeps did that in the 1920-1960s too or if some common knowledge has vanished with the marginalization of tube tech.

I wouldn't bother with the Matchless I really doubt it's a big enough difference. I could see trying to make a crappy amp better but it's chasing your tail trying to make a great amp better. Be happy play the sh!t out of it.

[JMFahey]

Fully agree.

Didn't know there was an EF86 version, I only knew and worked with the 6SH7 version, go figure.

There may be a slight difference using one or the other, it absolutely won't change amp sound per se, at most one will have a little more or less gain than the other, say like going from 6 to 6.5 setting on the volume pot, or viceversa; basic sound will stay the same, so even if you had both sockets factory wired and side by side (it's technically possible), on a blind test you wouldn't be able to pick which is which.

That said, the amp is killer, use it as is and be happy.

[martin manning]

There is a large difference in transconductance- 6SH7 is 2x EF86. Comparing the two circuits (as found on the web...) the plate load is 330k for EF86 vs. 220k for 6SH7, and the screen grid resistor is 2M2 vs. 1M. Not plug-and-play even if the pins were connected correctly, IMO.

[rp]

Interesting. So, I went and checked the Clubman schematic to see how Matchless handled it, but there's only the early 6SH7 one out there. Anyone got the latter EF86 Clubman schematic, or a link?

[tsutt]

One of my guitar instructors has one that he sent in for something else and the tech misunderstood and converted it to the ef86 and when he got it back he said they pretty much ruined it. it lost its sweet tone. he was really upset and still is.

[Phil_S]

One of my guitar instructors has one that he sent in for something else and the tech misunderstood and converted it to the ef86 and when he got it back he said they pretty much ruined it. it lost its sweet tone. he was really upset and still is.

Might it be the actual tube and not the tube type swap? What's stopping him from converting it back?

[rp]

Did Matchless themselves do it? Otherwise maybe it was done wrong, some tech just swapped the ef86 in without Martin to steer him right.

Tell teacher to have it converted back, the octal hole is already there, shouldn't be much time/labor involved if the socket isn't too buried in PTP hell. Find a good tech and ~$150 for re-found happiness sounds worth it. Hopefully Matchless gave him back his old 6SH7 but they're plenty and cheap.

I always wanted to build a Clubman clone. I'll have to read up if this is an other one of those endless "the original was better" stories.

edit: Phil beat me too it!

[tsutt]

Yep it was tube type swap while whats his name was there samson? it turned into some kind of problem wasnt able to send it back, then samson left and he didnt trust anyone. its a great sounding amp as is but he said it was quit a bit better before. i dont know if they gave him the original parts or not.

[xtian]

Hey, rp, you can see the EF86 Clubman schematic in the first post of my thread:

https://tubeamparchive.com/viewtopic.php?t=20741

I built this circuit. Even with the EF86 as the second stage following losses from the tone stack, it doesn't distort at all, even hitting the input hard. I found it doesn't really add any color to the circuit. Though, I had trouble finding an EF86 that functioned like I was expecting. The JJ was a bust, and I ended up with a Russian variant. A strong tube, but I don't know if it's a valid alternative to vintage.

Bottom line, the amp sounds great, and the owner loves it, but I don't think the EF86 contributed anything worthwhile.

[rp]

Thanks, the ef86 schematic doesn't want to google easy. I'm curious about the Clubman, I have a single 6SH7 in my stash, so whether I want to or not, before I die I will be forced to build a Clubman. There also a chance I'll be cured, but it's a slim chance at this point.

[rp]

Got this img off Xtian's build post. Way buried under PTP hell, lotsa work. Wonder whatever drove them the change it, misunderstanding or not you'd think they would have tried to talk the client out of it.

[tsutt]

My understanding they (matchless) was doing this to all they came in it wasnt wanted. he sent it in for something else.

[rp]

I can see that, it's an obsolete tube, can't expect (normal non amp dork) customers to go searching for NOS tubes, and internet and ebay were in their infancy in 1995. Bet swapping all the Clubmans made them rethink the wisdom of building ptp. Your friend should switch it back just to be ornery!