Marshall ecl86 13watter (similar to 18 watt schematic)?

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zaphod_phil
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Post by zaphod_phil »

I think there must be something else going on in your amp. My 13W Lite IIb has a classic 18W tone to die for - both crisp and crunchy, yet creamy smooth- and it's running the ECL86s at 300V. :) I've had both Tungsram and Mullard EVL86 valves in the amp too.

What screen and cathode resistor values are you using? What cathode cap value?

I did have to put in the Paul Ruby 18W buzz fix in this amp BTW.
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Post by katopan »

myamplifier wrote:Thanks for your help in this matter - I like the look of Doug Hammonds 10 watter
Just out of interest do you have a link for that? Searching didn't find it.
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Post by Jaicen »

Try searching for Doug Hammond Cirrus, I think that's what he called it.
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Post by zaphod_phil »

I know that amp pretty well, and was involved in some of the discussion on AX84.com when Doug was designing it. He wanted it to be kind of an AC15 derivative, with a few extra tweaks. You could likewise do a 10W Lite IIb with 6BM8 / ECL82 tubes, but you just need to bear in mind that they have less gain than the 6GW8 / ECL86 or 12AX7/EL84 combination.
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Post by Snapcase »

Not a bad idea using ECL82s for a 10 watter. They have lower gain than ECL86 but sound good. I don't have a wide experience with them but the later and more common version of the Dynacord KV10 has a couple with a ECC83 front end and it's a great little amp.
Last edited by Snapcase on Thu 03/04/10 12:46 am, edited 1 time in total.
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Post by katopan »

Thanks for the link. I have a couple of ECL82s out of an old 8W P.A. but had read (I think here) that they didn't sound that good (different distortion as well as lower gain) for an 18W sort of amp compared to ECL86s?
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Post by zaphod_phil »

Doug's Vox-inspired ECL82 amp sounds pretty good by all accounts, and there are some clips of it around as well. So I don't think an ECL82 version of an 18W would sound bad as such, but the lack of gain would be a bit of a handicap.
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Post by wombaticus »

zaphod_phil wrote:I think there must be something else going on in your amp. My 13W Lite IIb has a classic 18W tone to die for - both crisp and crunchy, yet creamy smooth, like melted butter - and it's running the ECL86s at 300V. :) I've had both Tungsram and Mullard valves in the amp too.

What screen and cathode resistor values are you using? What cathode cap value?

I did have to put in the Paul Ruby 18W buzz fix in this amp BTW.
Well, to be fair, my amp is a distant cousin of the 18/13W. But I was running it originally at 300V plate, maybe 295V Screen, Rk = 130R shared and 100uF of cap. Very hard sounding there. I have a custom 20W PP OT that I had Heyboer wind that can do 7.5, 9, 10.5 and 12K, which I have on a switch, but the sound of these tubes seems remarkably consistent over a wide range of impedences. Then dropped the screens to ~250V and saw a slight improvement. Dropping the plate to 280V helped even more, as did warming it up with a 110R resistor. But am currently running with plates just above 250V and screens just below, and this is the best yet, although I plan to drop the Rk further to 90R... these little buggers seem to like lots of current.

What's Ruby's 18W buzz fix? I'm new here.
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Post by zaphod_phil »

Still doesn't equate with what I've got. I'm running the ECL86s in my 13W at 300V with a 180 ohm cathode resistor, and individual 1k3 screen resistors. There's nothing special about that last value - they were just handy at the time in the right wattage. I've had a 63uF cathode cap, but am now running the amp with a 1000uF cap now for tighter bass. I'm using an 18W clone OT with 8k primary impedance. This is a real go-to amp for me. Very warm and mellow, with plenty of crisp definition at the same time. Since we run EL84s at 340V in a regular 18W, 300V should be no sweat for the mini EL84s inside ECL86s. I wonder if your harshness problem doesn't lie more in the preamp or PI.....
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Post by zaphod_phil »

wombaticus wrote:
Tue 03/02/10 1:16 pm
I recently completed an ECL86 based build, and I can report that the ECL86 at 300V sounded yuck, very harsh indeed. I would strongly recommend dropping plate voltage down to about 250V - it's quite nice there. This was observed with two separate pair of tubes from different makers.
I really don't understand why that would be. My own 13W, runs its power stage at 300V with a 180 ohm cathode resistor, and the breakup is beautifully creamy. I've had several other guitarists comment on how they love the warm tones of that amp. I've also used two different brands of NOS ECL86 valves.
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Re: Marshall ecl86 13watter (similar to 18 watt schematic)?

Post by zaphod_phil »

I thought I had already replied to this, but my response seems to have been sucked away somehow 8O :|

What I had said was that my own experience does not correspond at all with wombaticus' My own 13W Lie IIb runs its ECL86 pentodes at 300V, with 180 ohm cathode resistor +1000uF Cap. It is one of the sweetest sounding 18W style amps I have ever heard, with a very creamy breakup. Several other guitarists have also remarked how much they love this amp's tone. I've used both Mullard and Tungsram ECL86s in it, and the OT is a very accurate RS reproduction, built by Ingo Gorges.
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