New EF 86 any winners.

[drtool]

Well after 2 years on spare time, I finished one HF22. Tube joy for 5 min., then all hell broke lose. Bottom line, after checking my work for Hr. on end. The EF86 was on it's last legs. Checked fine. Changed to the only spare I had. Presto back in business. But wait... the sound. I look at it this way. I have a nice test tube.

So any winners in the new crop. Thanks Wayne.

 

[drtool]

Machine washer worthy, I hope.

 

[thorpej]

The JJ EF86s are pretty good.

 

[vaathi]

Good looking HF-22. I recently got one and I think I should look for a mate soon.

 

[drtool]

Thanks. I want one more for mono system #2.

 

[maxhifi]

The Svetlana EF86 is pretty good. You can get them on eBay pretty reasonably.

 

[dcgillespie]

In my experience, I've found the new manufacture EF86 tubes to have significantly different characteristics that will definitely upset the Eico circuit, and in particular, the HF-22 -- but they will still test just fine in a tube tester. The circuit was designed around the original British piece, which produced about 60 volts on the plate when operating in the HF-22. The new tubes however typically produce a much lower plate voltage, and also display higher gain as well. At the very least, this upsets the operation of the phase inverter stage. Therefore, to properly accommodate the new manufacture tubes, the B+ divider string usually needs to be altered to restore the proper B+ voltages to the driver and at the plate of the EF86. But doing this (i.e., restoring the driver stage operating point) then brings in all the extra gain the modern EF86 tubes produce, which then upsets the stability of the NFB network. Therefore, the NFB divider resistor usually needs to be reduced to maintain the specified 20 db of NFB as well. If you are using the stock circuit and new manufacture EF86 tubes and the sound was off, then I would bet this could be at the root of the problem. Either use good old stock tubes in your 22, or check that the front end operating parameters are as intended for the design when using modern manufactured ones.

That's a good looking 22! It does the washing machine proud!

Dave

 

[drtool]

Thanks Dave. The first tube was a screen Mullard. The 2nd was a newer, old stock Mullard I believe. But with plates and no screen. Pics to follow. I could not believe how much one tube change can make. A lot of the magic with my La Scalla was mia. I am learning a lot. Stock circuit.

 

[kvflyer]

You can get NOS EF-86 tubes from this vendor in Florida. $18 for I suspect USA and $24 for European tubes. I would call and see where in Europe. Could be Great Britain or a former eastern block country. Not necessarily a bad thing.

http://www.esrcvacuumtubes.com/vacuumtubes_tubelist_tubes_A24A6-ZM1032.html

I have purchased this tube from them in the past. It was not Mullard but it was vintage and good.

(No affiliation)

 

[drtool]

Thanks flyer. This was Holy Mooly.

 

[drtool]

Gordon W said to check out 6L6 Ruby. So I did Bought a match set of 4 for $52.00 shipped. Way good, right out of the box. Thanks Gordon. Figured if I fry the output tubes. I would rather lose one of them rather then the 5881 I bought of Bryce Youngman.

 

[s-petersen]

I use Valvo in many of my pieces, they seem to work well,

 

[dcgillespie]

Dr -- If you get a chance, post some voltage readings for the EF86 position with the two different tubes installed. The tube with the screen mesh shield is the classic Mullard tube that was always supplied with the Eico kits, and always works great.

Dave

 

[drtool]

Will do Dave. This is the stand I built. Satin paint does not repair like clear paint so this keeps the opt from touching any thing while in the operating room. I was told the Eico opt's were satin paint.

 

[Salectric]

I used a pair of HF-22 monos for a year or so back in the early 2000s. In my opinion you should get a nice set of old Mullards. They sounded the best of the several NOS EF86s I tried. The only modern version I tried was Electro Harmonix and it wasn't in the same league at all. Plus the EH had a little hum due I was told to some diffeeent shielding inside the tube. All of the vintage tubes were dead quiet.

 

[drtool]

Thanks Sal, that is the plan.

 

[Lavane]

Well, add this tube to my "don't buy new stock" tube list. Nice amp drtool!

 

[drtool]

Thanks Lavane. For the first time at this rodeo, I am super happy. I might try changing some R's, and seeing if I can get it to play nice with new gen. tubes.