EF86 replacement. Advice please

[Tone]

Hi all

I've been having an intermittent problem with my AC15 Heritage. When using the EF86 channel, every so often there will be a sudden volume drop as if it's gone from Pentode to Triode mode. and, indeed, if I jiggle the little Pentode/Trode switch it will come back to normal although sometimes (but not very often) it will do it of its own accord. I thought it was a faulty switch and I've just had it replaced but the problem is still there although inevitably it didn't show itself in the shop (like the rattle in your car which disappears when you take it to the garage).

I wondered if any other Heritage owners have experienced the same problem and, if so, what the solution was.

Meanwhile, the technician suggested that if it happened again I should replace the EF86 valve so I guess that's the next step. I know from previous threads that Watford Valves seem to be recommended but I've had a look at their website and there are loads of EF86 valves. Which one should I go for?

All advice appreciated.

Cheers.

Tony

[keithmantle]

Hi Tony, At the last Hankies Dan (Malcolm) Martins Heri was sounding off, and today my own was playing up sounded like the sound was breaking up at a certain volume and was also very 'Tinny', I think mine will be paying a visit to Amanda

[Amanda]

Hi Tone,

I've used Electro Harmonix EF86's and they seem a good valve,
I've had no problems with them.

There's some on ebay: item: 230402266469

They are cheaper than Watford I think as well!

Regards

Amanda

[Olsson]

Hello
I had the same problem with mine. I think thay are supplyed whit bad quality EF86. It has worked fine with a new valve.

/Bertil

[Tone]

Thanks for your advice, Amanda and Bertil. I'll go ahead.

Cheers.

Tony

[keithmantle]

Hi tony i think Vox say do not switch from triode to pentode while amp is switched on, Just bought 2 using Amandas ebay item number. Keith

[Amanda]

Hi Keith,

The piece about switching from triode to pentode and vice versa
referred to the EL84's although it's not in the latest versions
of the user manual. Whatever you do don't switch off, switch from triode
to pentode and then switch on straight away unless you want a blown rectifier!

It shouldn't make any difference switching the EF86 mode although you will get a "thump" in the speaker!