Interesting new valve amp product.

[jpfamps]

I've just been alerted to this product:

www.tubesync.co.uk

Any thoughts?

[Dmoney]

having a quick read. I don't really get it.

It's an on-the-fly auto bias adjust box of logic with some kind of circuit protection to save the amp in the event of an output valve failure?

some people like to bias their valves various ways... I didn't read a feature that describes being able to interface with that box to set a bias level.
I imagine it must get the various voltages needed to do a bias calculation into it, plus some juice to power whatever is in that box.
And this "valves up to temperature right from power up"... how is that possible! does it super heat them to a given point and then let your filament circuit do its job? surely that can't be good! I don't see how you can get around waiting a while for the filaments to be warmed up fully. Surely that is just physics, right?

Installing this into a PCB based amp doesn't look like fun. I would imagine you'll have to get rid of the usual bias circuit and install this thing. How do you effect what bias range it has to play with, say if you have an amp that can run anything from 5881 to KT88? I think most of the material about it suggests designing an amp that uses this as the bias system right off the bat, or adding into a turret/eyelet design.

would I really want a box to choose a bias level? would I want it to make little changes while I play to extend the life of my valves...meh. how much drift happens to the bias of output tubes over time anyway? a few miliamps?

could be a snazzy feature if someone built it into a new amp, but I don't think it is something that would mean that much to me if someone was trying to sell me an amp with it installed.

[gordiji]

sounds like a jolly good idea, if it works as it says.i'm in the process of educating and equiping myself to bias my own
amp though, so too late for me!

[Denim n Leather]

some people like to bias their valves various ways... I didn't read a feature that describes being able to interface with that box to set a bias level.

You can't:

"Amplifier configuration and tube type must be specified by the end user to allow the device to be configured accordingly "

[Dmoney]

i think if you can maintain your own amp etc... in terms of bias then this thing is kind of unnecessary.

if you use good valves, your bias won't really change that much for a good period of use.

you MIGHT at some point want to try a hotter or colder bias, and this thing doesn't look like it offers that... it just says it keeps your valves at an optimum level...
how does it find that? clever maths with reference voltages into it plus a memory of what 70% dissipation for a given tube type?

do you have to buy different units for different tube types?

installing something that can adjust the bias of each individual valve MUST be more complex than just swapping the bias pot in the average amp for this thing... as you probably know, the bias pot usually sets the bias of all your output tubes. In some amps you have split adjustable bias for each tube. Randall RM100 (i think) and some Egnater amps have that feature... as well as a lot more. if you have an amp with external bias test points, it's not a big job to check how things are running.

without know how to wire it up, im not sure how it would protect an OT from valve failure... arc detection? disconnecting a pair of tubes inc the faulty tube? the Orange Thunderverb has some kind of failure condition protection, where it can use 2 tubes as the backup for the others. not sure how that works though!


I just think, if you can bias your own amp easily, this thing (as cool as it may be) just isn't essential. If you have an amp with external bias points and individual bias for each valve, then... same again! that gets rid of the need for matched valves, and you can still check how things are biased easily. Then you're not trusting a little box to do it all by itself. In fact in a new amp, the cost of this unit may even outweigh the cost of designing a bias circuit as mentioned above.

how much does it cost anyway?

some people like to bias their valves various ways... I didn't read a feature that describes being able to interface with that box to set a bias level.

You can't:

"Amplifier configuration and tube type must be specified by the end user to allow the device to be configured accordingly "

Just read this... so yes, you have to specify, which i guess is fine, but then you're potentially loosing some flexibility once it is installed. Also, would you have to buy similarly rated valves from that point on? Maybe not, If it has a the reference voltages it needs to work out a preset idle current level for a given valve type.

[hunter]

Seems to do the same as Hughes & Kettner have in their new amps (you can mix any four octal base tubes and press a button and the amp will adjust/bias itself to it).

Seems quite handy and nice.

On the other hand, I wonder if it'll sound the same as a properly biased quad in a classical tube amp?

[HTH AMPS]

these guys are basically on my doorstep, like 15 minutes away - I'm gonna call and see if I can drop by to see this thing in action and get a better understanding of what it is.  if all it's doing is keeping the valves correctly biased and acting as a protection system, it seems a bit (lot) OTT.

[Dmoney]

Seems to do the same as Hughes & Kettner have in their new amps (you can mix any four octal base tubes and press a button and the amp will adjust/bias itself to it).

Seems quite handy and nice.

On the other hand, I wonder if it'll sound the same as a properly biased quad in a classical tube amp?

that sounds clever
however, this can only bias 1 type of valve within a given preset of parameters.
I imagine if you had this thing set up for EL34's and you swapped to 6L6 without changing the unit, you might have an issue.

28pins?
must be enough to give it plate voltage, bias voltage, idle current inputs and outputs (in the combination needed) for some gubbins internally to say "the user has EL34's and preferred Idle Current of X... Plate voltage is Y... EL34's currently at 24mA Idle... adjust bias voltage to make idle current = Z" (or it uses a more accurate system)

I dunno. It's automating something pretty simple right?
still. would I trust a machine to do it? I dunno, I would probably steer clear of an amp that had it inside. I'd still prefer individually biased valves, or split bias to bias in pairs. I think the robustness of valves is a bigger issue than constantly maintaining bias at 'micro' levels.

I guess the benefit of this and what Hunter mentioned is making things easier for everyone to maintain their amps and use tech's less, probably a better approach to the Peavey 5150 system. (fix the bias with the tubes really cold so that even a set of 6L6's that are naturally hot won't over stretch the amp ever)

speaking of mixed outputs...
http://www.youtube.com/watch?v=rEhFg1_JmjM
2xEL34 + 2x6550


hey!
this is also handy if you get music shop advice like i got down denmark street...
"matched valves are a myth, just get any type of tube you like and put it in your amp, you can mix types too, it doesn't matter. The difference makes it sound better..." cheers!

[Denim n Leather]

This is definitely one of the dumber things I've seen in my lifetime.

What will they think of next? Electronic guitar tuners?! PDT_008

[Dmoney]

hahaha

if by electric tuners you mean...
making a guitar and string that is pretty stable, and doesn't really go out of tune that much over time...
then making a system of tuners and such (a la robot guitar) to keep your guitar in tune while you play using mirco adjustment at the tuning pegs, however you can only ever use one kind of tuning and the same kind of strings to replace the old ones.

thats similar right?

H&K claim their system is the only one that lets you use multiple valves types, if that's true then whatever they made is a little better, and although not generally available it renders this device second best (at best) to their setup.


for me, depending on how it is wired, I wouldn't want a calculator plugged into the HV in my amp adjusting bias on the fly. I just like a simple amp, easy to maintain, as few parts to go wrong as possible. I'd have to add it to the list of stuff which is a good idea but probably won't end up in common use.

I'll concede that it is clever though

[Ratrod]

An auto bias system does sound like a good idea. But do you have to commit to one type of tube?

Lets say I have an amp with 6L6GC tubes, does that mean I can't install 6L6WGC tubes? Or 5881's?

[jpfamps]

I concur with most of the views expressed above.

Some of the newer Traynor amps have a "automatic" bias servo on them so you don't need to rebias (ie something similar to this). I suspect this has some sort of PIC control in it.

I can imagine a retro fit being quite interesting in some amps.....

[Dmoney]

An auto bias system does sound like a good idea. But do you have to commit to one type of tube?

Lets say I have an amp with 6L6GC tubes, does that mean I can't install 6L6WGC tubes? Or 5881's?

maybe that would work. I doubt it would bias anything accurately other than specified tube type and bias point.

if you use an online bias calc, you can easily see how the 70% dissipation idle current point with a given plate voltage changes for each tube (6L6, 6L6GC, 6L6WGC and 5881).

for example
6L6GC with an amp plate voltage of 475V has a suggested idle current of 44.2mA for 70% dissipation.
a 5881 in the same amp has a suggested idle current of 38.3mA
(http://www.webervst.com/tubes1/calcbias.htm)

If you wanted to use 5881, and changed to 6L6GC, I imagine the 6L6 would be biased colder.
the danger would be specifying a tube and bias point that could lead to an overly hot biased tube if you change tube type.
sticking with 6L6 types probably reduces the risk, but you wouldn't be able to adjust the bias point even if you wanted to.

the H&K thing is better as it allows any kind of octal base tube to be biased continually, it doesn't seem as limited.

It's probably a good thing it has some protection built into it as if its so new it may not have a track record for reliability, and since it is actively maintaining a very important part of your amp, if it did have some wild failure condition, you wouldn't want it to totally cut the bias to your tubes or something.

I just don't really see the need. It's clever... sure! but external bias points and test points and a multimeter will have you biased up an ready to go in a second. And I don't think 'micro-adjustments' while I play would make a difference to tone.
I think there are more reliable safety measures you could use to protect your amp also.
AND this 'tubes up to temperature from power on' thing I read, HOW DOES THAT WORK! the only thing I can think is you have the amp, totally unplugged and cold, you put in your power lead, plug it into a cab, turn in on ...this gadget super heats the filaments to get the tubes to an ideal temperature in the time it takes you to move your finger from the 'power' to the 'standby' switch.
rapid heating of tubes to get them to an operational temperature doesn't seem like a good idea me me. but then tubes can handle bigger filament voltages than 6.3V. so maybe a higher voltage is fine and heats the tube quicker. I'd like to know more about that aspect.

[Dmoney]

I concur with most of the views expressed above.

Some of the newer Traynor amps have a "automatic" bias servo on them so you don't need to rebias (ie something similar to this). I suspect this has some sort of PIC control in it.

I can imagine a retro fit being quite interesting in some amps.....

http://tubesync.co.uk/images/W210011.pdf

retrofiting this would indeed be interesting! especially in an amp with PCB mounted power valves
I guess the bias voltage is output from the unit on those pins G1 to G4
The calculation needed to work out how much bias voltage is needed is probably done using K1 to K4
not sure about the bottom right. diodes and 'aux' switches... interesting!