Anyone have Archon tube info?

[elvis]

Does anyone know what the recommended replacement tubes (pre and output) and bias currents are for the Archon 100 with 6L6?

Does anyone have a tube chart with function vs. location?

The Archon is a great amp, but the manual is not useful.

EDIT: The location and bias information is posted in one of the replies...

 

[HANGAR18]

I feel your pain. I had to contact the PTC to get the bias settings for my Archon when I switched from 6L6's to EL34's. The voltage for the 6L6's seems to be a lot lower than the voltage for the EL34's because I had to raise it quite a bit when I made the swap. All I got from them was the voltage for the EL34's so maybe you can post their answer here after you contact them. Then we'll both know.

 

[dsenoj]

Did they recommend 30mv for the bias setting for the EL34's? I think it will be the same setting for the 6L6, you just have to make a fairly large adjustment to get the same reading with different tubes.

But double check with PRS, don't take my word for it.

 

[Deleted member 5962]

Have you looked inside the amp? I asked that when I got my Custom 50. Asked PRS customer service and they answered quickly.... so I took the back of the amp off to swap one and every tube was labeled on the inside of the amp. If I had looked inside, it was all there. Try there first, and if it's not there PRS customer service will let you know.

Meanwhile, I got some questions for you.

 

[Dusty Chalk]

Yes, that is correct -- it's 30mV irrespective of the tube, that's how you adjust the amp for a different tube type. Did you get a different answer, Hangar18? It is a range -- you can set them as high as 32mV or as low as 28mV, but that's not a function of the tube, that's a function of whether you want to run it hotter than normal or cooler than normal. You should set them all the same (I'm making the actual numbers up, but I don't think it's much more than that).

I'm not a professional, so you should verify everything I say.

 

[bodia]

I had kind of the same question for an HXDA. Iwas asking what NOS tubes they would recommend. Emailed customer service ([email protected]) and had answer back the next afternoon (I emailed after hours). And DTR is correct, they are clearly labeled on the inside. In my case it was a sticker on the right side with positions listed and hand written tube types listed.

 

[elvis]

Thanks for the replies! I pulled the back cover and did a thorough inspection and nothing was labeled anywhere in the cabinet. The power tubes have a hand-wrtten number (like 27), but I think that is from bulk testing for matching.

I checked the existing bias as a baseline. I got 30, 29, 30, 30. So that corroborates those who weighed in.

 

[elvis]

As a matter of interest, if you put the amp in 50W mode, the outer tubes remain on, with a bias current of 34mA (regardless of whether I change the impedance setting as the manual recommends) and the inner tubes are 0mA.

 

[jc986]

All the stock preamp tubes used are JJ, and the stock power tubes are Ruby 6L6GC-MSTR (which are Chinese Shuguang).

 

[Boogie]

The bias adjust control on PRS amps is a balance control, not necessarily a current value adjustment. The tubes draw the current they want and you control the flow so that values are as close together as possible. That actual value isn't as important.

 

[elvis]

Got this from PRS. Ruby power tubes and JJ preamp tubes. And 30mA is the recommended 6L6 bias.

 

[Dusty Chalk]

The bias adjust control on PRS amps is a balance control, not necessarily a current value adjustment.

I thought that the way to switch tubes was with a current adjustment...?

 

[elvis]

The bias adjust control on PRS amps is a balance control, not necessarily a current value adjustment. The tubes draw the current they want and you control the flow so that values are as close together as possible. That actual value isn't as important.

I don't think this is accurate. Changing the bias trim changes bias of ALL the output tubes, and it can go way beyond the narrow range of appropriate bias, such that it can be rebiased for EL34. You have to buy matched tubes to get matched bias.

I can't imagine how you would balance bias of 4 mismatched tubes, in any possible combination of mismatch, with a single bias control.

 

[Boogie]

Pull out a VOM and check for yourself. I've swapped a bunch of power tubes on my Super Dallas and know the routine pretty well. There are two sets of probe ports on the 100w and one set in the 50w amps. But not all amps are built alike so yours may differ. But the HXDA and variants have this setup. Setting the bias, for me, involves obtaining the closest readings between the two tubes. This is also why you buy matched pairs and quads. Check your manual.

If you have 4 mismatched tubes, you made a mistake.

 

[elvis]

I've biased amps for years. I suspect we are essentially saying the same thing, but in different terms. In my experience, you set the bias up for the correct current (in the case of the Archon, it's 30mA, or 30mV via the test points) and the last thing you do is tweak it so that the majority of tubes are as close the to the right number as you can. You can balance to a degree, such that if one tube reads 28 and one reads 30, you can set them around 30, such that one reads 29 and the other, 31. But you can't get them to be any closer to each other, thus, the matched sets. But you can also set them to 15, or 40. These would be inappropriate, but my point is that the bias control sets the absolute value, not the matching. I've never seen an amp that works in a way that is different from this, but YMMV.

It's possible I am misinterpreting your use of "balance".

 

[Boogie]

I suspect we are essentially saying the same thing...

Me too.

Yeah, your description is absolutely accurate. The "difference" between the tubes is inherent in the selection process. As you twist the bias adjustment pot you are striving for the smallest differential, closest to the target setting, 30mV. I was spoiled by Mesa/Boogie for so many years where they did the heavy lifting for their customers. Fixed bias designs are stupid-simple for maintenance. My old Fenders didn't have squat (except for a paultry "Hum Balance" control) and required much more work...especially Twins...the exact opposite. Having probe ports readily accessible on these old school amps is a huge convenience. And not having to replace resistors or install a potentiometer is fantastic, too.

 

[bodia]

Does anyone know what the recommended replacement tubes (pre and output) and bias currents are for the Archon 100 with 6L6?

Does anyone have a tube chart with function vs. location?

The Archon is a great amp, but the manual is not useful.

EDIT: The location and bias information is posted in one of the replies...

Just curious if you put new (or nos) tubes in your Archon? If so, what did you go with, and what were the results?

 

[elvis]

I was spoiled by Mesa/Boogie for so many years where they did the heavy lifting for their customers. Fixed bias designs are stupid-simple for maintenance. My old Fenders didn't have squat (except for a paultry "Hum Balance" control) and required much more work...especially Twins...the exact opposite. Having probe ports readily accessible on these old school amps is a huge convenience. And not having to replace resistors or install a potentiometer is fantastic, too.

Agreed. I had to pull the chassis to bias my Shiva, by comparison the Archon will be SO EASY to set up. I've also been spoiled by Mesa amps and fixed bias, but I like that I can adjust as the tubes age now. The bias ports are the greatest.

 

[elvis]

Just curious if you put new (or nos) tubes in your Archon? If so, what did you go with, and what were the results?

I'm just getting spare tubes for now. I'm not much of a tube-roller and I don't ever buy NOS. For preamp tubes, I've never been particular enough, and for power tubes it's not worth the expense to me, as I have to change them every 1-2 years.

 

[Ascension]

Got this from PRS. Ruby power tubes and JJ preamp tubes. And 30mA is the recommended 6L6 bias.

Thanks so the pre amp configuration is really exactly the same as it is with the MT 15 except they reverse what they call V 5 and V6 between the 2 amps and that's what I suspected it to be.Still in the same physical slots though but on the MT 15 the effects driver at the end of the front row is labeled V 5 and the PI behind is labeled as V 6 the opposite in what they label the same slots on the Archon. Why who knows?? At least now I know for sure what tube does what function. Own both a MT 15 and a Archon 50 head.