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Orange TubeSync DIVO OV4 -Biasing Kit-

#5
Well, the Bassman 300 has a trim adjustment on the back that made biasing rather easy for me in the past. I personally have never had a problem with it there and haven't heard of someone getting shocked from it there ( not saying it isn't possible).

I completely understand keeping the less informed dirty fingers off of a amp, but would be nice for the well informed.


BassmanPaul said:
Why?? If they existed, someone would just HAVE to mess with them. I prefer bias pots inside the amp - they're safer that way.
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#7
As much as I will disagree, I'll agree regarding DIY'ers doing their own stuff.

I don't want to hijack my own thread, haha, but there are a lot of risks out there that can destroy a amp that would be user error besides biasing. So, there is some knowledge out there to maintaining your gear properly. Biasing is another one of those things that if you mess up..... well it can cost you extra money.

I'm a huge DIY'er, as a lot of TB members here. So I enjoy seeing new products and ideas. I enjoy doing the research, taking care of my own gear, and knowing how to maintain it as well.

Anyways, whether there should be a biasing pot or not would be pure opinion, I suppose. Because some companies have them and some do not. I believe there should and you believe they shouldn't... No right or wrong answer there.






BassmanPaul said:
I'm less concerned about electrocussion than an uninformed user "fixing" the bias on an amplifier that is working perfectly.
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#8
I am posting in the hope of reviving this thread. I called Orange today to see if this device can accomodate amps that use four KT88 power tubes. The rep I spoke with was courteous but really only told me as much as was written in the user's manual, which I (of course) had downloaded and read before calling Orange. The literature states that it can be used with KT88 tubes, and with amps that have four power tubes, but the literature also only makes reference to using the OV4 in 50 and 100 Watt amps. No mention of using this in a 200 Watt, 4 x KT88, amp is made, despite the fact that Orange produces a 4 x KT88 amp in the AD200B.

So, after hanging up with Orange, I emailed TubeSync in the UK, who is the producer and designer of these units for Orange. They sell their own versions as well, including kits to hardwire their tech into existing amps. I'm hoping to get a more definitive answer directly from those who designed this device. This seems like some very thoughtful technology, and I am impressed by the concept. The idea of being able to roll power tubes at ease, and the ability to cut to half-power/100 Watts, seems great ..... useful. The ability of the unit to test and bias the tubes at every power-up, as well as to manage how the tubes receive power at start up, and when idling, seems like a very logical/practical advancement.

>> http://www.tubesync.co.uk/
 
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#9
Sorry it's been three years since I last posted in this thread. I have forgotten what this device is and the original link is toast.

Is your amplifier working properly as it should? If yes leave the thing alone and play. If not take it to a knowledgable tube tech and get it fixed.

A tube amp is dangerous to folk who are not accustomed to working with high voltages. Amps in this and higher wattages can be deadly to unknowing hands.
 
#10
My amp works great and is properly biased with matched pairs of JJ KT88s. I have knowing hands, or at least 'knowing enough not to kill myself' hands. I like to tweak all of my gizmos when I am able, be they cars, bicycles, sailboats or tube amps. One of my pet peeves in general is the evolution (de-volution) of non-user friendly/serviceable devices, especially cars. It drives me insane that I cannot fix a modern vehicle, the way I could fix just about anything that burned gas when I was younger. Those signs that say, "No User Serviceable Parts" make me breathe fire. I despise planned obsolescence!

The antidote for this poisonous assault on my sensibilities lies in playing through hard wired tube heads and driving old cars :thumbsup:

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CIMG0657-1.jpg


But also, this device really impresses me because it does not involve exposing oneself to anything dangerous for installation. The Orange video on this unit says that a tech is needed for installation anyway. The OV4 is a totally non-destructive, easily removable, modification, which is a real plus with vintage amps that lose value when not kept all-original spec. I am interested in improved tube protection, maintaining proper biasing over time as power tubes drift/wear, the ability to easily roll different power tubes (even unmatched sets, so they claim) without having to pull the chassis and get out a multimeter and consider potentially risky voltages, and the feature of being able to go with half-power. My tube amps work great as they are, but this device, if it does as stated, will make my amps work even better.
 
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#11
The video that was (dead) linked above is here, and it does actually use the AD200B as an example of a head that the OV4 can be used with. Oddly, the Orange rep on the phone today was unaware of this. Hopefully the definitive answer will come from TubeSync.

 
#13
BassmanPaul said:
And how does this device deal with the inherent problem created by switching a pair of tubes out of the circuit? The output is no longer matched to the plate to plate load of the output tubes. This results in stress to those tubes thus shorter life span.
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Good question that I don't know the answer to. I'll ask them, if they reply to my email.
 
#14
BassmanPaul said:
And how does this device deal with the inherent problem created by switching a pair of tubes out of the circuit? The output is no longer matched to the plate to plate load of the output tubes. This results in stress to those tubes thus shorter life span.
Click to expand...

I don't believe there is any additional stress.

Tubes are transconductance devices, ie, the output is a current that is proportional
to an input voltage. They behave like current sources.

The output stage simply loses the contribution of the pair of tubes that was removed.
The remaining pair do not try to make up the missing current.

The impedance mismatch is also such that the load impedance is too low. So there is also
no danger of the excessive voltage that occurs in the opposite condition, when the load
impedance is too high.

(edited)
But yes, the impedance match does need to be restored somehow.

-
 
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#15
megafiddle said:
The impedance mismatch is also such that the load impedance is too low. So there is also
no danger of the excessive voltage that occurs in the opposite condition, when the load
impedance is too high.

-
Click to expand...

So this would be similar in theory to running a 4 Ohm cab with an amp with its OT tap set to 8 Ohms? The mismatch causes no damage to amp or power tubes, but does cause a decrease in power output (aside from the halving of power from cutting out a pair of tubes). Correct?

Seems to make sense as I recall a guitar player who had a Hiwatt 100 watt head that he had pulled one pair of tubes on, to get earlier sag/breakup at lower volume. His cabinet was a 16 Ohm 4x12, and he turned his OT tap setting from 16 to 8 Ohms, to compensate for the changes from going with half the tubes. Hope I am remembering that correctly. :laugh:

I definitely remember that the difference between 50 and 100 watts with that Hiwatt was a lot less than I had anticipated. Either way, that amp played very loud without much breakup (with guitar, not bass). It really seemed almost no different with half the tubes removed.
 
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#16
Boot Soul said:
So this would be similar in theory to running a 4 Ohm cab with an amp with its OT tap set to 8 Ohms? The mismatch causes no damage to amp or power tubes, but does cause a decrease in power output (aside from the halving of power from cutting out a pair of tubes). Correct?
Click to expand...

Not exactly the same. In the first case, with a tube pair removed, the speaker
and transformer secondary current does not increase.

When you lower the speaker impedance, the secondary current will increase.
That means more heat in the transformer. The output power is still less though,
because of the decrease in voltage.

That doesn't happen when you pull a pair of tubes, because nothing is changing
in the load circuit (the transformer secondary and speaker). The mismatch in this
case is between the tubes and transformer primary.

The output transformer secondary looks more like a voltage source. If the load
impedance decreases, the secondary current increases. Tubes are more like a
current source. If the tube impedance load decreases, the plate current doesn't
change.

Boot Soul said:
Seems to make sense as I recall a guitar player who had a Hiwatt 100 watt head that he had pulled one pair of tubes on, to get earlier sag/breakup at lower volume. His cabinet was a 16 Ohm 4x12, and he turned his OT tap setting from 16 to 8 Ohms, to compensate for the changes from going with half the tubes. Hope I am remembering that correctly. :laugh:

I definitely remember that the difference between 50 and 100 watts with that Hiwatt was a lot less than I had anticipated. Either way, that amp played very loud without much breakup (with guitar, not bass).
Click to expand...

Yes, you do get an impedance mismatch when you pull tubes and lose potential power.
Lowering the tap impedance by 1/2 or raising the speaker impedance by 2 restores the
impedance match.

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#17
I run the ad200 into two orange 410 cabs and I can confirm that using the divo ov4 with the ad200 works. I been using it for about a year and I have had zero problems. The half power mode works with the ad200 as well, but you need to buy a special pedal that is sold separately from the divo ov4. Let me know if you have any questions.
 
#18
Wow, without quoting you guys, there is some great info coming through here. Thanks for the clear explanation, megafiddle.

And Devin, that is good news to my ears since the device should work well with my Simms-Watts, which is also 4 x KT88. Did you need to have a tech install the device, as Orange recommended, or were you able to install this yourself?
 
#19
I did it my self as a dumb 19 yr old and it was very easy. The hardest part is actually putting the tubes back inside the chassis of the amp because the divo ov4 adds about an inch of height to the sockets. It's a tight fit and I shattered a tube on accident. If you ever get it, I can take a picture so you can exactly how it goes
 

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