EF86 issue in Morgan AC20 Deluxe

ryanverbena

Hi all. 

Today I replaced what was already an old microphonic ef86 in my Morgan AC20 purchased from the forum a few months ago. It seemed like a decent choice but upon arrival today it has shown to be microphonic as soon as I tried it. After messaging the seller he wrote back right away and said  "There may be some incompatibility with your amp / guitar. This is not a reflection on your amp / guitar, just possibly an incompatibility issue".

I'm not very technically minded in this area, so could anyone point me in the right direction to find a "compatible" tube for my amp? I understand that ef86's are notoriously unreliable, but hoping to purchase the right tube to get this glorious channel up and running again. 

Here is a link to the tube in question btw:

https://www.ebay.co.uk/itm/194040585934

Cheers!

Winny_Pooh

Only one I found not to be microphone (vs 2x new production and a vintage telefunken) was a certain old Mullard. I may still have it somewhere if you are interested to buy a known good one. 

Technically speaking that valve you bought will test fine, it's just microphonic so not suitable for a guitar amp. Return it.

Ef86 are notorious for being sensitive like this. It's been more commonly used in mics (like the Neumann U67) and pres which have way less physical vibration than a combo guitar amp.  

djspecialist

I recently replaced a slightly microphonic EF86 in my Bad Cat Cub with a Dario Miniwatt from Watford Valves. No microphony and it sounds great.

ICBM

I have never understood why EF86s have become desirable for guitar amps again. They stopped being used in the 1960s because they’re more expensive, often microphonic, and have less available gain* and flexibility in use than an ECC83. Those things are all still true today.

(*More than *each half* of a twin triode, but a lot less than both together.)

That said I had a few of them and most weren’t microphonic. I think I’ve sold most of them now but I may have one or two left if you can’t get a good one elsewhere.

I don’t like the sound of them in guitar amps either, personally...

Modulus_Amps

ICBM said:

I have never understood why EF86s have become desirable for guitar amps again. 

Me too, maybe ok for guys that are building there own amps and are happy to work through rubbish valves, but not for mass produced products

ryanverbena

Thanks for the advice guys - think I will return the valve in question. @Winny_Pooh - PM incoming  

I'd never owned an ef86 amp before this and given what I'd heard about the unreliability of the valve (as summed up above), I doubt I would have purchased an amplifier that relied solely on an ef86 in V1. But the Morgan having two different preamp channels was too good of an offer to pass up. 

FWIW - I love both channels on this amp, but there really is something amazing about the ef86 channel. I've done blind tests, brought them both up to same volume/gain levels, etc - and I always find there is something in the ef86 that is missing from the 12ax7. At first I thought this could have been explained by the brand of valve used, but I've now tried a bunch of NOS (Brimar, Mullard, GEC, Svetlana, JJ), and whatever the difference is definitely between the ef86 and the 12ax7 type rather than the brand of valve. 

That said, I think the amp is ace and if the ef86 channel stopped working completely I'd still keep it just for the 12ax7 channel. 

ToneControl

in my experience most of them are very microphonic, even the brand new, cryo-treated ones I tried

I bought a job lot of old used ones and just used the quietest one that sounded decent.
AFAIK they have a long lifespan in use, I've been using that tube for a very long time now

ToneControl

Modulus_Amps said:

ICBM said:

I have never understood why EF86s have become desirable for guitar amps again. 

Me too, maybe ok for guys that are building there own amps and are happy to work through rubbish valves, but not for mass produced products

there's a lovely shimmer in the treble frequencies that I have only heard on EF86 amps, very noticeable with single coils
e.g. I only use the ef86 channel on my DC30

I'd be happy to try alternative amp designs, I think the cleans on the Matchless Independence were close

ICBM

ToneControl said:

there's a lovely shimmer in the treble frequencies that I have only heard on EF86 amps, very noticeable with single coils

One man's lovely treble shimmer is another man's overly hi-fi clean and slightly metallic overtone .

ryanverbena

ToneControl said:

Modulus_Amps said:

ICBM said:

I have never understood why EF86s have become desirable for guitar amps again. 

Me too, maybe ok for guys that are building there own amps and are happy to work through rubbish valves, but not for mass produced products

there's a lovely shimmer in the treble frequencies that I have only heard on EF86 amps, very noticeable with single coils
e.g. I only use the ef86 channel on my DC30

I'd be happy to try alternative amp designs, I think the cleans on the Matchless Independence were close

I agree with the shimmer description - I described it to a friend as a more textured high end, almost like a soft reverb decay. I do play this channel on the edge of breakup clean btw, middle pickup on a les paul and use the tone knobs to balance the pickups.

I find the ef86 channel pulls the bridge pickup out of the mix and gives a stereo like quality. I'm aware that sounds a bit wanky, but that's how I'd describe what I'm hearing. 

maw4neu

I've got a couple if your stuck . . both were fine from memory but I bought a NOS Mullard for a small fortune and I put these two away in a "safe place" . .  Too "safe" as it turned out as I actually lost them for nearly a year . .  I did have one or two more but they are either "lost in the attic" or gone with one of the Artisans I've owned . . . 

hywelg

Modulus_Amps said:

ICBM said:

I have never understood why EF86s have become desirable for guitar amps again. 

Me too, maybe ok for guys that are building there own amps and are happy to work through rubbish valves, but not for mass produced products

Because Matchless.........


Mullard EF86's didn't used to be that dear. And I found that they work very well 

ryanverbena

maw4neu said:

I've got a couple if your stuck . . both were fine from memory but I bought a NOS Mullard for a small fortune and I put these two away in a "safe place" . .  Too "safe" as it turned out as I actually lost them for nearly a year . .  I did have one or two more but they are either "lost in the attic" or gone with one of the Artisans I've owned . . . 

Thanks for the offer mate but I already took @Winny_Pooh up on his offer! Cheers 

Dominic

Hi Ryan
I know the amp well ....it was a Mullard in it If I remember correctly .......Ihad originally tried about 4 different valves and the Mullard was by far the best but I had a previous EF86 amp too and I find the whole EF86 issue a pain because that was the same.

Moe_Zambeek

Add me to the ‘prefer ECC83’ camp. I disliked the ef86 channel in my dc30 - clanky metallic harsh top end, especially when driven hard, restricted EQ, tube sensitivity... I just never used it. 

I have a few ef86s here that worked well with it but I felt that needing a hoard of ‘special’ tubes just to keep it working wasn’t really a great idea.

ToneControl

Moe_Zambeek said:

Add me to the ‘prefer ECC83’ camp. I disliked the ef86 channel in my dc30 - clanky metallic harsh top end, especially when driven hard, restricted EQ, tube sensitivity... I just never used it. 

I have a few ef86s here that worked well with it but I felt that needing a hoard of ‘special’ tubes just to keep it working wasn’t really a great idea.

interesting:
like @ryanverbena , I wouldn't go beyond mild saturation on that channel

for full-on OD, I'd be using ecc83/12ax7 in a different amp

Moe_Zambeek

Welll yes...all is relative though - I mean driven hard in a DC30, which means fairly mild overdrive really. Any more than 12 o clock and the noise would be excessive. 

Dodge

Moe_Zambeek said:

Add me to the ‘prefer ECC83’ camp. I disliked the ef86 channel in my dc30 - clanky metallic harsh top end, especially when driven hard, restricted EQ, tube sensitivity... I just never used it. 

And me. I did once play an old AC30 that someone had added an EF86 to via a kit. It did sound good clean, just not as good as the stock top boost channel when pushed. The kit was velcroed to the inside back panel which apparently helped lower the microphonic tendancy of the valve. Not sure about that, but anyway....

I didn't use the EF86 channel at all on my DC30. It's a shame they didn't do something else with that channel really. For what was a pretty decent sounding amp, that channel wasn't even average. I found it very fatiguing.

ryanverbena

Dominic said:

Hi Ryan
I know the amp well ....it was a Mullard in it If I remember correctly .......Ihad originally tried about 4 different valves and the Mullard was by far the best but I had a previous EF86 amp too and I find the whole EF86 issue a pain because that was the same.

Yes correct, it was a Mullard Dom. I tried a few others with no luck but hopefully sort that out soon with one incoming from the forum. In any case, absolutely love the amp on either channel 

ryanverbena

Agree with all of the above, edge of break up with the guitar volume rolled off is as far as she goes.

I find it too loose when it overdrives, almost like a fuzz pedal starved of voltage (and not in a nice way).

So +1 in the camp of 12ax7 for dirty tones