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Hot Rod Deville 410 with JJ 6v6s

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  • 14-08-2009 1:37pm
    #1
    fistikuffs
    Closed Accounts Posts: 32 ✭


    Hey there, I just recently bought a second hand HRDv 410. It's my first tube amp so I'm loving the sound of it compared to my Marshall 150 AVT but like all the reviews I read before buying it said, it's too damn loud.
    First band practice the amp never went above two and didn't sound very special at all. I felt like crying:(

    So as opposed to going down the attenuator route or selling the amp I decide to go with the JJ 6V6s retube kit from Eurotubes. Swapped the tubes out yesterday and set the bias to 38mv and so far so good. The volume, on the clean channel at least, is much more manageble, pretty comfortable around 3-4 and so far I really like the sound of the JJs. In fairness though I'm only comparing it to what was in it which was 2 mesa 6L6s, 1 electro harmonix and 1 stock 12AX7 and a JJ EC88s and I don't know how old they were.

    Anyway has anyone else tried this option? How did it work for you? I've read that if you're going to consider this as a permanent option you might want to change the screen resistors and the output transformer. So maybe it's going to be a different amp after all.:(
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    #2
    Paolo_M
    Registered Users Posts: 880 ✭✭✭Paolo_M


    fistikuffs wrote: »
    Hey there, I just recently bought a second hand HRDv 410. It's my first tube amp so I'm loving the sound of it compared to my Marshall 150 AVT but like all the reviews I read before buying it said, it's too damn loud.
    First band practice the amp never went above two and didn't sound very special at all. I felt like crying:(

    So as opposed to going down the attenuator route or selling the amp I decide to go with the JJ 6V6s retube kit from Eurotubes. Swapped the tubes out yesterday and set the bias to 38mv and so far so good. The volume, on the clean channel at least, is much more manageble, pretty comfortable around 3-4 and so far I really like the sound of the JJs. In fairness though I'm only comparing it to what was in it which was 2 mesa 6L6s, 1 electro harmonix and 1 stock 12AX7 and a JJ EC88s and I don't know how old they were.

    Anyway has anyone else tried this option? How did it work for you? I've read that if you're going to consider this as a permanent option you might want to change the screen resistors and the output transformer. So maybe it's going to be a different amp after all.:(

    Screen resistors are predominantly present to protect the valves screen from burning up uynder large signals.
    If your ear is pretty well tuned then you'll notice a bit more compression in the tone as you use larger values of this resistor.

    You need to measure B+ and the corresponding screen voltage and compare it to the JJ 6V6 spec sheet.
    The screen is particularily important, but if it's within the value on the spec sheet then you're good to go.
    I'm in Thailand at the moment and I'm not sad enough to know the value is off the top of my head (though it's somewhere in the 400Vdc region). The screen is pin 4.
    Of course you'll need a multi meter to check this, but because you can adjust the bias, I'll assume you have one.

    I'm pretty sure that a pair of 6V6s ideally need to see twice the load of a pair of 6L6s. You don't need to replace the OT for this. Using a 16 ohm speaker into the 8 ohm setting on the amp (or similar) will do just fine. I can't remember if the Deville has the built in speaker or not. Either way using a higher ohm value speaker will be cheaper, and be easier to revert back to original than replacing the OT.


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    #3
    fistikuffs
    Closed Accounts Posts: 32 ✭fistikuffs


    Paolo_M wrote: »
    Screen resistors are predominantly present to protect the valves screen from burning up uynder large signals.
    If your ear is pretty well tuned then you'll notice a bit more compression in the tone as you use larger values of this resistor.

    You need to measure B+ and the corresponding screen voltage and compare it to the JJ 6V6 spec sheet.
    The screen is particularily important, but if it's within the value on the spec sheet then you're good to go.
    I'm in Thailand at the moment and I'm not sad enough to know the value is off the top of my head (though it's somewhere in the 400Vdc region). The screen is pin 4.
    Of course you'll need a multi meter to check this, but because you can adjust the bias, I'll assume you have one.

    I'm pretty sure that a pair of 6V6s ideally need to see twice the load of a pair of 6L6s. You don't need to replace the OT for this. Using a 16 ohm speaker into the 8 ohm setting on the amp (or similar) will do just fine. I can't remember if the Deville has the built in speaker or not. Either way using a higher ohm value speaker will be cheaper, and be easier to revert back to original than replacing the OT.

    Hi Paolo, thanks for the reply. It's a little over my head but I do have an idea of what you are talking about. With regards to the screens and resistors I take it that the screens are in the tube and the resistors on the pcb? I've read a little about this before mainly on Justin Houltons site but i'll have to get an electrician friend to help me with this. So what i need to do is get both those measurements compare with the spec sheet set the bias for 70% dissipation and if that's all ok i should be good to go?


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