AD30 Plate Voltage

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Farrerdale Records
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AD30 Plate Voltage

Post by Farrerdale Records » Sat May 19, 2018 4:42 am

Hey Folks,

I fell down the rabbit hole of looking at tube specs and noticed that two EL84 in push pull, like the AD30, have a max plate voltage of 300V. What's the plate voltage of the AD30?

Thanks

Jondog
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Re: AD30 Plate Voltage

Post by Jondog » Sat May 19, 2018 2:31 pm

Not sure of exactly how high, but it's more than 300 vdc. I may be corrected, but I think it's the current that is the bigger issue. It's limiting value according to JJ data is 300v at 65mA. You'll see on the graph, less current with more voltage. I'd guess the AD30 is around 330-350vdc on the plates and somewhere around 35-45mA depending on actual wattage.
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Re: AD30 Plate Voltage

Post by Farrerdale Records » Sat May 19, 2018 3:59 pm

Thanks Jon, and I'm guessing it's 335V but like you said, the current would be lower to compensate. After I posted I looked up the data sheets for the 6V6-GT I have in my Deluxe Reverb and for 70% dissipation at 425V plate, the current is 19mA-ish, when the tube is rated for 35mA @ 315V (92mA @ 285V for push pull, two tube class A operation).

I originally tripped on this when rethinking the PI slot, the design is for a 12AX7 which has a low current (1mA) and transconductance (1.6), and therefore 1W plate dissipation, while the 12AT7 has high current (10mA), transconductance (4.5), and 3W dissipation. I wondered what effect the higher current draw in that circuit would do compared to a 12AY7, which is listed with 3mA current, 1.7 transconductance, and 1.67W, thinking I could get higher output/headroom with 12AY7 with less current than the 12AT7, meaning the components aren't working as hard for close to the same effect.

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Re: AD30 Plate Voltage

Post by Jondog » Sat May 19, 2018 5:43 pm

Gain factor is another thing to consider.
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Re: AD30 Plate Voltage

Post by fiveightandten » Sun May 20, 2018 1:50 am

AD30 plate voltage spec is 340VDC. I've seen it as low as 300V and as high as 360V in the AD30's I've owned. Mind you, this is with consistent mains voltage.

You really have to take the whole operation of the tube into consideration. I wouldn't fixate on plate voltage alone. You should also look at screen grid voltage. However, the most important thing, IMO, is to ensure the plate dissipation is within spec. You can push the plate voltage, and to an extent the screen grid voltage, as long as the dissipation isn't too high. That's when you start chewing tubes up and having early failures.

I haven't had an issue with an AD30 eating tubes, and the one I use the most is running WAY hotter than spec. It's the one with 360 VDC on the plates, and the dissipation is running way hotter than spec as well. It's the best sounding AD30 I've heard, and the EL-84's have been fine in it. Actually, the hotter power transformer sounded so much better than I swapped it from my combo to my head, because I wanted to use a head for convenience, but the lower voltage PT in that amp just didn't sound as good.

Anyways. Long story short, I'd load tubes into the amp, make sure they're not red plating, and just use the thing. If you want to get into finer detail, you really have to measure your own AD30 and compare that to the spec for the tubes you're actually using. There's a fair bit of variance going on between units and tube sets.
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Re: AD30 Plate Voltage

Post by Farrerdale Records » Sun May 20, 2018 4:30 am

Thanks, I really appreciate the information!

I have an older AD30, I got it around 02 or 03, are there better PT and OT that people have found over the years?

I just generally love learning about and using the amp and it's components more and more.

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Re: AD30 Plate Voltage

Post by fiveightandten » Mon May 21, 2018 2:16 am

Farrerdale Records wrote:
Sun May 20, 2018 4:30 am
Thanks, I really appreciate the information!

I have an older AD30, I got it around 02 or 03, are there better PT and OT that people have found over the years?

I just generally love learning about and using the amp and it's components more and more.
IMO the Demeter OT's used in the later (2006 and on, I believe) AD30's sound better than the OT in the earlier heads. I have a Mercury Magnetics OT in my TC head, and that's a nice sounding iron.

All 3 OT's sound a little different. The Demeter OT is like $80 direct from Orange, and IMO it's worth the money too upgrade over the earlier iron. The Demeter sounds a bit clearer and more defined, IMO. It's more musical and has better note definition.

The Mercury OT is expensive, so you'd have to be looking specially for the sound it gives to justify the cost. It's noticeably fatter sounding, and has a more pleasing tone. It's tough to describe, but the harmonic content when overdriven just sounds more aligned. The stock Orange OT's make the amp more finicky with pitch. If you have a discerning ear, you'll hear that the guitar needs to be tuned VERY well, and notes need to be played without pulling the strings out of perfect alignment with each other. Otherwise, the pleasant overdrive character is replaced by messy sounding odd order harmonic content.

The MM OT eliminates that. The amp is more musical sounding, and doesn't overdrive into odd order messy sounding saturation when your notes are out of perfect tonal alignment. The downside to the MM is that you really have to keep the bass knob in check, or the low end can overpower things. Also, the sound is more polite. So if you're looking for a raunchy overdrive, I'd go with a Demeter. The note definition of the MM OT is a bit better as well, but not enough to outweigh the difference in harmonic alignment and the difference in the low end response. Those are the more notable differences, IMO.

Mercury Magentics - If you want the fattest sound. If you want the most musical and pleasing sounding overdrive. If you want sweet sounding overdrive without worrying about perfect intonation and technique.

Demeter - If you want better clarity and note definition than the older iron. If you want a raw sound and the ability for a more aggressive, raunchy overdrive, at the expense of the amp being more finicky with intonation and pitch alignment.

Stock OT - If you don't play the amp past 50% on the master volumes, if you largely play clean, or if you're not concerned with the attributes mentioned above that the other OT's provide.


In terms of PT's, I've only really just heard the variance from different stock PT's. I have not used a MM PT. Higher B+ voltage makes the amp sound brighter, less gainy, louder, and more aggressive. Lower voltages yield more pre-amp gain, more low end, less top end, and a darker more saturated sound.

The AD30 is a nice sounding circuit, built to a price point, and revised a few times. They had transformers spec'd by at least 2 different suppliers, as the amp went through some revisions over the years. There's some variance, and therefore some room for preference between units. I took my AD30s apart and swapped parts to get one that I liked best. I now use a 2011 head with a 2006 PT, and the MM OT in it. I preferred that PT, as it's putting out pretty hot (over spec) B+ voltage, and to me it sounds best. I also changed the slop resistor value for the channel 2 tone stack, to lower the mid hump a bit. I prefer the MM OT for what I do.

FWIW, the tone difference between the stock amps that I have was larger than the difference from swapping different OT's. The B+ voltage variation between the PTs was huge, and yielded most of the tone difference between amps. Hope that helps.

-Nick
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Re: AD30 Plate Voltage

Post by Stymie13 » Tue May 22, 2018 4:39 am

Great post, thanks for sharing.
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Re: AD30 Plate Voltage

Post by Farrerdale Records » Tue May 22, 2018 5:01 am

After reading the comments on the OT, and doing more research on the tubes, 15W on an EL84 is the max power potential than can be achieved before failure, with voltage and current ratings inverse to accomplish the desired results, as long as the equation does not exceed 15W per tube.

Which led me to believe that it's really the OT that is responsible for the final power RMS rating of 22W clean for the AD30, even though there is a quartet of 15W tubes with 60W of total potential.

Is that a fair assumption? It seems the OT can have a incredible impact on the sound.

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Re: AD30 Plate Voltage

Post by Les Paul Lover » Tue May 22, 2018 7:51 am

In terms of power valves, you can also look into replacing the EL84 with Russian NOS 6P14P EV valves.

The EV part is important as it designates military grade valves. They can take up to 500v and higher plate dissipation, and are designed for 5000 to 10000h use- 10 times more than regular EL84.

They cost about the same as a regular set of EL84 too.
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Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5


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Re: AD30 Plate Voltage

Post by Farrerdale Records » Thu May 24, 2018 11:44 pm

Though it doesn't seem worth it in terms of volume and complication, accruing knowledge for knowledge sake, would it be possible to to reduce the output wattage like the Tiny Terrors do? How would that work?

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Re: AD30 Plate Voltage

Post by Les Paul Lover » Fri May 25, 2018 12:02 am

Farrerdale Records wrote:
Thu May 24, 2018 11:44 pm
Though it doesn't seem worth it in terms of volume and complication, accruing knowledge for knowledge sake, would it be possible to to reduce the output wattage like the Tiny Terrors do? How would that work?
It becomes complicated. The PCB isn't designed for that.
You could try EL844, lower output EL84.

Instead, I'd recommend tracking down an AD15, or a Genz Benz Black Pearl 30. The latter isn't miles away from the AD30 (Still different, a little less gain overall), but it can switch from 7 to 15 to 30w.
Ant

Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5


Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute

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Re: AD30 Plate Voltage

Post by Jondog » Fri May 25, 2018 1:01 am

You could pull two tubes. Just match tbe impedance.
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Re: AD30 Plate Voltage

Post by fiveightandten » Sat May 26, 2018 8:45 pm

Jondog wrote:
Fri May 25, 2018 1:01 am
You could pull two tubes. Just match tbe impedance.
What about the remaining tubes running off 150 ohm cathode resistors as singles (doubling the dissipation)?
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Re: AD30 Plate Voltage

Post by Jondog » Sun May 27, 2018 1:40 am

fiveightandten wrote:
Sat May 26, 2018 8:45 pm
Jondog wrote:
Fri May 25, 2018 1:01 am
You could pull two tubes. Just match tbe impedance.
What about the remaining tubes running off 150 ohm cathode resistors as singles (doubling the dissipation)?
I put could in italics because it’ll work, but best with mods to the bias as well. I was partly thinking of the Dual Terror, although it’s bias resistors (150ohm/two tubes), but it is wired differently. One resistor/two tubes in push pull configuration. Best to do it right. I would mod the amp if I were to do that.
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