Orange Dual Terror choke addition

[ReginaldBisquet]

Been rocking out with the Dual Terror for several months now and enjoying every bit of tone it delivers. While having lunch with a good friend, he mentioned how the Dual Terror really needs a choke for better performance/longevity.

I opened up the chassis of the amp to see if I could find the resistor where the choke would be inserted:


... and got distracted by checking out this little feature at RV7:



Did some digging around and came up with this explanation from the Orange forum:

What it (most likely) is, is a 100 ohm or so pot across the heater filament taps with the wiper going to ground. This creates an artificial centre tap. You adjust the pot until the winding are balanced across the pot. This point gives minimum hum.

Why it reduces hum is because it creates two 3.15 voltages 180 degrees out of phase that when combined to run the heaters cancel any ac hum you normally get. Basically in the same manner as a humbucker pickup works.

You can set the pot while the amp is on, that's really the best way to hear what you're adjusting it. It still might not get rid of all the hum if you have noise on your line or a ground loop with a pedal or something like that.

Interesting! I'll have to give that a try sometime.

Anyway - sorry for the tangent - if anyone has added a choke or even upgraded the transformers of a Dual Terror, please let me know.

[lowell]

Check out these 2 threads.

http://music-electronics-forum.com/t...ighlight=choke

http://music-electronics-forum.com/t...ighlight=choke

[lowell]

Check out these 2 threads.

http://music-electronics-forum.com/t...ighlight=choke

http://music-electronics-forum.com/t...ighlight=choke

[Chuck H]

The hum balance control has been around as long as tube amps have. But I guess it's the silver face Fenders (64 to 8?) that were first to use them in guitar amps. The prallel out of phase thing is correct, but not exactly as it was explained. Sometimes dual triodes or AB power tubes have an imbalance in gain or filament characteristics. In a perfect world they would balance on their own since both halves of the filament winding (if there is a CT) or the false CT (usually a pair of 100ohm resistors) are also balanced. If everything is balanced you would indeed have dual out of phase hum on either winding lead, but... It's because nothing is ever balanced as it should be that the "hum balance" control works. Sometimes they need to be adjusted quite out of balance to equate the hum level on either end of the wind. So in the end it's the same result, but the pot is there to provide the neeeded imbalance rather than balance.

FWIW an elevated DC bias for the filament CT is a better way to cancel hum. It's a simple circuit and has been covered here ad nausium. A search should provide any info if your interested.

P.S. I got to put my own amp up against the Dual Terror at the 2009 Winter NAMM show in so cal. It's a great sounding and versitile design that was almost as good as my "boutique" amp. Probably as good in any way that counts. A very humble moment for me. Why would you want to change it with a choke. Is it under performing??? Is there something about the envelope/attack that you want to change???

[Steve Conner]

+1. I'll bet it doesn't "need" a choke. It might give a tiny reduction in hum and half a watt more output, or something, but to install it you'd have to hack up that nice brand-new amp and drill holes in it. I'd say nuh-uh.

Your friend didn't work for Mercury Magnetics by any chance?

[ReginaldBisquet]

True, true. I was told by my friend that any guitar amp over 15 watts needs a choke. And since he's a trusted friend, I started looking into the idea. I tend to run my amps at full throttle (no pedals) with the guitar volume doing the overdrive work... and I think this is why he recommended I look into a choke.

I've been more than happy with the performance and tone from amp since I bought it on Craigslist earlier this year (July). Played several gigs along with hours of rehearsal and home noodling... no complaints.

Steve Conner's sig ("I'd probably modify anything I bought, no matter what it did." - R.G.) sums up my outlook on gear very neatly.

[Tom Phillips]

... any guitar amp over 15 watts needs a choke....

Such absolute statements are not absolute truth. It simply depends on the overall design and the result that you desire.
Cheers,
Tom

[lowell]

Yes if you're running your amps at full tilt and you get your overdrive from the amp itself, then it's very likely a choke is counterintuitive for your setup and sound. That being said you can still get "sag" AND use a choke via other means/mods.

[ReginaldBisquet]

Gigged last night... another successful performance from the Orange!



I was thinking after I struck the first chord, any change I make to this amp will be negated once the rest of the band kicks in. I'm leaving well enough alone with this amp.

Thanks for the insight!

[Chuck H]

Wow that Jaguar in all black with chrome looks tre' cool. Where's your neck pickup? Otherwise thats a lot of wasted switches, right?

I'm glad your leaving the amp alone. I really thought the Dual Terror was a good design. Much better than a Tiny Terror X 2 if you get my meaning. And the TT is a good amp. The DT is going to be one of those amps you read about having been used on a bunch of recordings some fifteen years from now and then everyone will want one and Orange will "re-issue" it...

[ReginaldBisquet]

Thanks Chuck! It's a 2005 Japanese crafted. I completely gutted the guitar when I "rescued" it from Craigslist. It was a bad shape with divots on the fret board, dents in the frets, the body was scratched and dinged up - and I found dirt and dead bugs in the cavity!

Went out and picked up parts at Darren Riley's Web shop and installed a TV Jones Classic Plus along with a stainless steel Compton bridge. Nice growl and sustaining kerrrang! It’s also a one volume control guitar now - installed a treble bleed circuit (a la Seymour Duncan) so it stays clear when turned down. I may re-install the high-pass filter one day - but I seriously doubt I will ever re-install the neck pickup control function. Just too fussy for what I need out of the instrument.

Ironically, soon after I bought this guitar, the Blacktop series started coming out. Oy vey!