What's the deal with EL86 amps - Lafayette 250A etc?

[loomis]

I just picked up at an estate sale a Lafayette 250A integrated amp for fifty bucks. I have no clue how people determine if it's a KT-250A or an LA-250A. It doesn't say. Is this Japanese or US-built?

Anyhow, it's an EL86 Mullard amp with 7199's. What's the deal with EL86 / 6CW5 amps? Why weren't more made? Seems kinda odd.

And what is the consensus with swapping out the 7199's with 6GH8A's? I see adaptors on ebay. Yes I read the thread here about a seemingly failed attempt to swap to a 6U8, and that was just sorta unresolved...

Curious to know about this amp other that the couple old threads on here. Thanks.

 

[gadget73]

The 6GH8 and 6U8 are approximately similar designs to the 7199, being a pentode/triode tube with similar characteristics. 7199's are expensive compared to either of the other two so some folks modify things to take a much cheaper tube.

Only thing I've ever seen with an EL86 is my Norelco tabletop radio. it uses an EL84/EL86 pair in a strange cathode follower configuration along with no output transformer, a big coupling cap, and 800 ohm speakers. I've never run across anything that used them for output tubes in the more conventional sense. I believe Phillips was the only outfit that made a lot of OTL designs that used the EL84/EL86 pairing in that way.

 

[loomis]

Wonder why the EL86 wasn't used more? It seems like a good performer.

And why haven't 7199's been remanufactured exactly?

 

[Tom Bavis]

6CW5s can actually deliver more power than 6BQ5s, but it would take class AB with fixed bias, and ideally a regulated screen supply. I think the simplicity of 6BQ5 cathode bias won...

As for the 7199, I've converted several amps successfully to 6U8 or 6GH8, and have more in the wings... my Stromberg ASR-880 may keep the original 719s, probably nothing else will. I have heard that the Russian 7199s (now obsolete...) were repinned 6BL8s - another 6U8 sub.

 

[radioactive]

. I have no clue how people determine if it's a KT-250A or an LA-250A. It doesn't say. Is this Japanese or US-built?*

Kt would be a kit and la would be factory assembled. Tell tale signs would be rivited sockets for the factory assembled but is not a gaurentee.

 

[byoungman1]

Yeah, Sovtek offered 7199's for a while. Probably quit making them because no current-production equip. uses that tube.

 

[peterh]

Yeah, Sovtek offered 7199's for a while. Probably quit making them because no current-production equip. uses that tube.

No they did not offer 7199. They offered a different tube with the same name.