Orange's New Valve Testing and Biasing Units

[P-oddz]

It seems to me that its niche is not necessarily for people who don't know how to operate tube amps, but rather give a tool for people into tube amps (who don't understand the exact minutia of their guts) allowing them more control over certain aspects of the amp (tube swapping and biasing in particular)- rather than having to rely on an amp tech for everything regarding the amp's upkeep.

Obviously, as mentioned before, one should DEFINITELY be knowledgeable to a certain extent as there are life threatening voltages at play when messing around with the guts of an amp. And in no way does this replace the good ole' amp tech, but I can speak personally as a new tube amp owner (yes, an Orange AD200B) - that a tool that would be available to help me self-service my own regular maintenance issues (tube replacement and biasing) while hypothetically lessening the tube replacement cost, could be extremely useful. Not to mention if you don't know any "guys" that work on amps locally, the thought of finding someone for a routine maintenance issue seems like a complete headache.

At least that's how I'm understanding the product... maybe I'm wrong(?)

[MAMMOTHvolume]

Originally Posted by B-string

The problem is the gain measured at a relatively low plate voltage may be meaningless at full plate voltage which also varies with design. If they managed to get even 100 VDC from the 19 VDC supply, it could mean little in the amp running at 600 VDC on the plate supply.

You could get 1000v from a 1v input if you wanted. It's better to test valves at a comparative REGULATED voltage to establish a baseline. There is little to be gained at testing at higher voltages.

[seamonkey]

Originally Posted by P-oddz

Are there actually still tube diagnostic machine manufacturers for Orange to put out of business? Every machine I see available on the interwebs appears to be decades old.

No.

There's the Orange is Kiosk like testing.

Here's what Hodgy at Ampeg mentioned he uses:
http://www.maximatcher.com/maxipreamp.html
http://www.maximatcher.com/maximatcher.html
These are on a much different level

[P-oddz]

After finding more info on it, it appears that an amp tech needs to install the OV4 system and you don't really have much control over its adjustments, as those are made on the service tech's side (preventing noobs like myself from making power biasing errors that would be detrimental to the functionality of the amp). From what I gather, it regulates tube use and biasing (for the user) and also serves as a sort of diagnostic for the tech.

[B-string]

Originally Posted by MAMMOTHvolume

You could get 1000v from a 1v input if you wanted. It's better to test valves at a comparative REGULATED voltage to establish a baseline. There is little to be gained at testing at higher voltages.

It is nice we disagree.

[mjac28]

Originally Posted by JimmyM

I miss the days when every drug store had a tube tester. And tubes.

+1 I forgot about that they needed them for all of those old tv's and radio's.

[B-string]

Originally Posted by mjac28

+1 I forgot about that they needed them for all of those old tv's and radio's.

They were only simple emission testers but the stock beneath them was real convenient

[beans-on-toast]

The DIVO OV4 bias system has been around for a couple of years. Yes, it has to be set up by a tech and leaves little control for the user. It is a lot more cost effective to keep a supply of matched tubes on hand rather than pay for a computer to monitor it and tweak the amp on the fly. It looks good in principle but hasn't really caught on. Maybe because of the expense. It's way overpriced.


Here is another currently available tube tester, the AT1000.

[Mr. Foxen]

Originally Posted by P-oddz

From what I gather, it regulates tube use and biasing (for the user) and also serves as a sort of diagnostic for the tech.

Orange amps are so simple that needing a diagnostics package would give me severe doubts about the tech.

[P-oddz]

Originally Posted by Mr. Foxen

Orange amps are so simple that needing a diagnostics package would give me severe doubts about the tech.

Originally Posted by beans-on-toast

It is a lot more cost effective to keep a supply of matched tubes on hand rather than pay for a computer to monitor it and tweak the amp on the fly. It looks good in principle but hasn't really caught on. Maybe because of the expense. It's way overpriced.

I get what you're saying, guys. Humor me another question (as I'm really trying to increase my knowledge of this topic).

When you replace tubes, don't you still need to have them biased?

It is my understanding that a bias is necessary with tube replacement. So doesn't the OV4 hypothetically cut down on the cost and time away from your amp (the time it would take for a tech to actually get to replacing tubes among his current workload, and biasing them, plus the expense for his time)? Maybe this wouldn't really pay for itself (to Beans' comment on expense) within a tube replacement or two, but after that, wouldn't it be sort of cost effective? Especially if it helps to prolong the life of your current set?

But to that point, Foxen do you mean that it's so simple that any amp maintenance on the Orange is so low in cost (because of its simplicity)? And Beans, is that what you're saying about the cost effectiveness of matched tubes. Do you not have to bias because they are claimed to be matched tubes?

Thanks for any responses guys, it's helping me to understand things better.

[Mr. Foxen]

Originally Posted by P-oddz

I get what you're saying, guys. Humor me another question (as I'm really trying to increase my knowledge of this topic).

When you replace tubes, don't you still need to have them biased?

It is my understanding that a bias is necessary with tube replacement. So doesn't the OV4 hypothetically cut down on the cost and time away from your amp (the time it would take for a tech to actually get to replacing tubes among his current workload, and biasing them, plus the expense for his time)? Maybe this wouldn't really pay for itself (to Beans' comment on expense) within a tube replacement or two, but after that, wouldn't it be sort of cost effective? Especially if it helps to prolong the life of your current set?

But to that point, Foxen do you mean that it's so simple that any amp maintenance on the Orange is so low in cost (because of its simplicity)? And Beans, is that what you're saying about the cost effectiveness of matched tubes. Do you not have to bias because they are claimed to be matched tubes?

Thanks for any responses guys, it's helping me to understand things better.

Ashdown made an amp you could bias yourself, the Peacemaker series all used the trademark VU meter as a bias meter, and each valve had its own bias, so you didn't need to match them. It isn't a complicated procedure if the amp is made to have it done easily. Some Peaveys like the 5150 mkii have contacts you put a voltmeter into to set the bias, as does my Matamp, its a case of turning a knob until the meter says when is generally printed on the amp. Don't need a complex device for it, just an allowance for doing it in the design of the amp.

Problem finding in an Orange should be easy because its a very simple circuit, but fixing it is harder than it could be due to the cheap construction. Matched tubes still need to be biased, just as long as they are actually matched for the conditions in the amp, its only one adjustment rather than one for each tube.

Hiwatt amps had no bias adjustment because if you had a Hiwatt, you'd be using decent valves, and decent valves were consistent, the whole mathcing thing is a result of the quality drop when they became obsolete.

[P-oddz]

Thanks for the info, Foxen

[beans-on-toast]

There is a lot of misconceptions about matched tubes and biasing. First of all tubes are not matched the same way. Unfortunately, there isn't a standard that everyone follows. Resellers do whatever they want and call that matching. Ideally, you want the tubes matched at the plate voltage that the amp operates at. A tube set that is matched at one voltage, may not be matched at another. Tubes are non linear devices. When you test and match a tube, there are a number of different tests that can be performed. I would want tubes matched at the plate voltage of the amp, with the bias type, be it cathode or fixed bias, and then matched for transconductance and current draw. Most resellers do not go to this extent. A lot of them claim that they are selling matched and tested tubes when they aren't. Some will gladly take the tubes back if there are issues but depend on you to weed out the bad ones. With equipment you can test this but you aren't paying to have to do this. Finding a reliable seller that you trust is important.

You can buy tube sets that are both matched and optimized to run at the bias that is set within the amp. That is what I was referring to above.

In the old days you bought a set of tubes and they were all within a close tolerance that nothing needed to be done. The amp's performance can be optimized by adjusting the bias. A properly biased amp will sound better. But it doesn't need to have the bias set exactly the same for all the tubes. Nor do the tubes have to be exactly matched. I would argue that this can add character to the tone of a musical instrument amp. So one question to consider is, will the amp sound better with an OV-4 in place?

As was mentioned, some amps like the SVT, have test points and pots on the chassis. You plug a voltmeter in and adjust the pot. Biasing is easy. On other amps, it isn't so easy.

With a fixed bias amp, the bias voltage is dependent on the wall voltage. Bias the amp at one location where the wall voltage is 120V, go somewhere else where it is lower (because the wiring is dodgy) or higher and your bias is going to be different. Your amp is going to sound a bit different that night. Bias also changes as the tube ages. I like to check it once a year.

I think that the OV4 could be a useful tool. It monitors current flow and biases the amp on the fly keeping things as close to perfect as possible. If a tube shuts down, it compensates. It allows you to mix different tubes and optimizes the bias. All good things. I'm just saying that at the price, it is a hard sell. Players that are into high technology will like it and will gladly pay for it.

A set of power tubes can last years. I see forty year old plus amps that still have their original tubes in them and they are doing fine. People who gig their amps regularly as well as those who use their gear less often still need to have regular maintenance performed on their amps. Checking the bias while this is being done is not a big deal. So if you don't change your tubes that often, it will take a longer time to justify the cost of the unit.

This is what I envision for the future. Have a small low cost micro-controller board in the amp. It has a USB interface, better yet a mode of wireless communication. The board monitors tube current draw. An app on a computer or smartphone that allows you to set parameters on the board. The technology is available, it is fairly simple to implement, and it can be done at a reasonable cost.

[P-oddz]

Thanks for the response, Beans. This is all very helpful information as I try to understand (at least) the basics of tube amps.

[beans-on-toast]

You might find this short tutorial on bias of interest.

[P-oddz]

Thanks a lot for the link- I appreciate all the help!
I will definitely give it a read.