spaceatl

Sure. Happy to share what I do, but keep in mind that I do NOT speak for Line 6 and if you want to learn about taking care of a tube amp, there is plenty of good information on the web...Lots of good how to's about setting the bias on a tube amp...I would never discourage someone from wanting to learn this stuff...Just keep in mind that the voltages are dangerous...THEY CAN KILL YOU...However, there are safe procedures anyone can follow and learn how to do it safely. the bias adjustments only apply to the Class AB Mode...You would actually figure this out pretty quickly when you meter read zero on the test points in Class A. Master Vol all the way down....After all, adjusting bias is about the "idle" state....If you put the amp on standby, you will have no readings...It becomes pretty clear once you are into doing it...You are just taking measurements... One note is that you do not need to let the amp warm up to measure the plate voltage....You can simple take out the tubes, power up and measure it fro mthe tube socket...This can give you decent starting place for calculating safe bias level (in my DT25 case 414 volt plate; 70% of 12 watts = 20.4mv bias target) My own procedure for adjustment with new tubes is to: remove the old tubes with the power UNPLUGGED FROM THE WALL. turn the bias adjustment(s) fully counter clockwise. (All the way down) power on for 5 minutes on standby Set as CLASS AB power up off standby and take measurements immediately....bias should be very low... Switch to CLASS A let them cook for 5 or 10 minutes Switch to CLASS AB start adjust the pot(s) up slowly until I hit the target. Let it cook for another 15 minutes check again and adjust play on it for a couple of days check and adjust as needed The voicings and pentode/triode do not change the plate voltage at all. I measured the plate voltage in each state in case an average would be needed.... I have my amp set Class AB/Pentode with Master down...NFL made no difference to the bias that I could measure...

both

Phil, I need a beer for each time you have answered this one...check you contract... :D http://line6.com/supportarchivenew/thread/86741/

thanks man...That was my impression that its purpose was directed as a live capture interface...I'm waiting on one to arrive and am very excited to get going with it...It's seems exactly perfect for what I need right now...16 discrete tracks of live capture with a few monitors mixes for the takes....no computer needed...This is will be a serious burden lifted for my workflow...

As I recall, the DT25 is using something like a FET buffer to hit the inverter tube...Certainly it I would think it was a somewhat evolved design...But it is also a different design with different concerns in terms of the power tubes...EL34s are a different animal...a whole lot of power there... I think dropping one tube has everything to do with heat and insuring the EL84s stay stable...ALL EL84 amplifers run very hot and designing this one to run plates at over 400 volts, stay stable and switch modes in a small form factor might have been just enough for them to go for Class A solid-state buffer to feed the inverter over a 4th tube...EL84 amps are hotrods...I think this one is extremely innovative design that looks to me like it might be built to last...

weird...So it doesn't work as the Advanced Manual describes? Input Streaming Configuration The M20d streams 20 inputs to your computer and a stereo stream back to the M20d as follows: • Channels 1-16: M20d Mic/Line Inputs 1-16, pre-processing / pre fader • Channels 17-18: M20d stereo Aux Input, pre-processing / pre-fader • Channels 19-20: M20d stereo Main Outs, post-processing / post-fader USB Stereo Return Stream: The stereo return is streamed to the M20d’s stereo Aux Input (channels 17/18). Note: In order to hear the stereo return, a Stage Icon Preset must be assigned to the Aux Input using the M20d touchscreen UI. The Laptop preset is ideally suited for this purpose, and can be found in the Stage Icon Gallery. For USB audio streaming, you must download and install the Line 6 StageScape M20d Driver at http://line6.com/software. On that page you will find 3 drop down menus. On the All Products drop down menu select StageScape M20d. On the All Software drop down menu select Drivers. Select the OS of the computer you wish to use with your M20d. Once the download has completed, find and run the StageScape M20d Drivers Installer, following the onscreen instructions. In your DAW you will need to change your audio interface to ASIO StageScape M20d. Then create new audio tracks in your DAW with inputs that correspond to the inputs on the M20d. Note: If you are using the StageScape DX/MME driver, make sure that StageScape is selected as the default audio device in Windows. Also, know that you will only get audio from inputs 1-2 if you are recording with DX/MME. The Windows StageScape M20d USB 2.0 audio driver uses WDM and ASIO, supported on 32 and 64 bit OS configurations. The Mac OS X StageScape M20d USB 2.0 audio driver uses Core Audio, supported on 32 and 64 bit OS configurations.

I listened to the clip...If that is really HD500, guitar and cans...that's sounds like a bad wiring job in that guitar or you are using a defective cable or even perhaps a speaker cable (no twisted pair)... Outside this being a crummy cable, the first thing that comes to mind is that none of the wires in this guitar are utilizing twisted pair...This is actually extremely important in a passive guitar...And if you want to do it perfect, it is a royal pain in the arse to dress it out properly twisted...Properly twisted means that "every" hot gets a ground from the star in every switch position, runs are twisted as tight as possible with as many twists as you can get and the NUMBER of twists in EACH run is an even number... It's an art...But when you do it, electromagnetic noise will cancel...Shielding does NOTHING for an electromagnetic buzz, that only helps with electrostatic noise (this guitar has a lot of that too)...Most of the time when I have re-wired a guitar that sounds like this one it turns out that there are multiple ground paths in the scheme that were done out of convenience without insuring that ground it twisted around every hot and that the ground is conductive...The more switches an pots you have, the more difficult this becomes logistically...

This is not as mystical as it is being made out to be...Unfortunately, getting a bad tube happens more often now than it did in the past. As the inventories drop, the will continue to be the case. I think these days, the Russian tubes tends to be reliable...I tend to stick with Russian on power....12AX7s you can do what you like...just stay away from the long plates... I am about to order new power tubes for my DT-25...I really want to try a nice pair of 7189s in this amp....but those things are $$...hard to find real ones...

I have been told by Line 6 from the beginning to use short plate 12AX7s in the Bogner amps....SVs too...In the DT25 there is only one 12AX7 and it is an inverter...part of the power amp....

Yes, tubes last a little longer in any AB tube amp running 70% vs 83%...But tone can get cold also....So there is an ear component to this as well...Mine sounds great to me, so I leave it at the typical 70%...Always a compromise between stability and finding the magic happy place....70% is very typical...and economical... Tubes are tubes....Not many factories left, so It's all about the curve trace matching and the traces themselves...A nice matched set at 10 grid bias intervals works fine for me...There is a difference in terms of the curve response the designer wants in terms of obtaining the aural vision and the technically tolerances that will function just fine. The notion of designing a tube amplifier to a very specific tube curve trace with extremely tight tolerances is a throwback to 40 years ago....There simply is not enough tube stock to select from to build amps like that anymore....Back then, fixed bias meant fixed bias...you did not put pots on it, you used resistors...and you have the curves for your amp and you replaced the tubes with a close a match as you could find...If this were really true, certainly RB would have insisted on the curves being in the manual...

We have not been able to get much in terms of answers about target bias % on a DT-25. So I pulled some of my notes from 2-3 years ago the last time I measured my DT-25 and I have gone ahead and done some measurements on my DT-25 head tonight...Just in case this was bothering anyone else as much as it was bothering me. Keep in mind that I am not am employee of Line 6. I wanted to know what the Line 6's bias target % for my amp so I can at least have it operate in a safe range if I have to change tubes at a gig quickly. Needless to say, my queries went un answered. EL84 tubes are pretty notorious for thermal runaway (red plating)...In a typical amp that experiences a run away tube, this would means checking the filter caps, grid resistors (AB) and/or the cathode resistor (A). But these amps have some digital stuff and heat and extra current draw is not good thing around that stuff anyway. So what's the deal? Transformers for power means everything is relative to the input voltage and could vary by 5% in multiple spots along the way. So your amp might slightly different... house voltage:120.8 volts AC Class A plate voltage: 404 volts DC Class AB plate voltage: 414 volts DC So this is that basic information we need to make an "informed" bias calculation for AB Mode. No Need to worry about Class A, that's a Cathode resistor and basically the mode is safer than fixed bias where the grid resistors run much hotter. What Line 6 states: 25 mv (+- 3 mv) Well, my amp has never been biased that high. However, if I were to set my bias to 25mv, with my plate voltage being 414 volts, then I am looking at 83%...If you are up around 420, then 25 mv puts you at 90%...Why does an AC30 keep flashing thru my brain?...Why even change modes? anyhoo... What I am doing: I have been running this amp at 70% bias since it arrived... 20.29 mv would be perfect...I am right around there...I have had this DT-25 since before they were released and I have been using it regularly (once a week for 2-3 hours). Much heavier the first year...One tube change right around the time they were released (amp was 3 or 4 months old at that point). Stock tubes are fine and are in the gig bag for spares... Anyway, this is what I know about the DT-25....DT-50 is way overdue for a tube change and I am doing a bias mod to that amp...I will post my findings on that amp at a later time...hope this helps at a few of us that know this stuff isn't as much voodoo as has been made out.

Sorry, I did NOT ask for the bias or the plate voltage values....just what you think the bias % target is for Class AB Mode...

:wacko: --- And the plate voltage is? Without revealing anything...Can you tell me your bias percentage target? Is it typical 70%...That's really all I would like to know...

This is what I use now....Sorry, not sure what a good Euro product would be.... http://www.tripplite.com/line-conditioner-1200w-avr-system-automatic-voltage-regulator-power-conditioner-ac-surge-protector~LC1200/ In the past when I toured in Europe, I used a Furman AR-15. Basically, my gear is US (all 110v) so I would just use a step down tranny in front of my AVR.

Power Conditioning and Surge Protection only offer partial protection and can do little about a ground loop... My suggestion would be to get a power isolation transformer....You can kill three birds with one shot by getting a transformer based AVR (Automatic Voltage Regulator)...switching type (non-transformer) AVRs are NOT the same thing. Something like a Tripp Lite LCR1200 will give you stable regulated voltage, power conditioning and isolation...It's the isolation property of a transformer that can be most helpful...Ground loops will not go thru a transformer since there is no physical connection.... Here's a good paper on the subject... http://web.mit.edu/jhawk/www/tmp/p/EST016_Ground_Loops_handout.pdf

some more specific information would be helpful... screenshots or something....What messages are being show to you?

B has two outputs...So what you want is an 8 ohm cab if you want to use it with your internal speaker... So yes, you can move the internal speaker from the 8 ohm out to one of the 4 ohm outs...plug your 8 ohm cab in the other and you should be good to go...

Maybe check out an ENGL 850/100...

I guess you could...might need an adapter...Seems like you could use the left line input on the back...set it to -10 db and save using an adapter...

There is no magic setting for leveling the relative volume of patches....No other way than setting the master and leaving it, then going thru the patches and adjusting the channel volume only...

sarcasm....Syndrome was the bad guy Joe....but I guess it pulled your string...

You can use a conventional mic cable...high quality and up to around 20' max length is what I would suggest if you go that route.... An AES/EBU is actually the proper cable...A DMX rated cable will work well also....

A Weber MASS is a speaker you ninny muggins :P ....pretty sure speakers have always been reactive loads...But if you don't think so, that's fine...enjoy!

In terms of alternatives, I think there are many....I would probably start with the Slo Clean model, even one of the bass amps might get you there for the Super Clean....I would suggest the PRE versions of the models since you are coming from X3...No need to get all complicated with the FULL amp model(power section) as it might color things too much for what you want in terms of replicating this patch...but lots of option to try... For the direct chain, I think I would leave an second amp block empty and perhaps put a Vintage Pre on the second chain...Pre isn't in the Amps, it's an FX block...Spring verb for sure....you have 8 blocks to play with...I am pretty certain you can spin up a new patch that would do as well or better than your X3 does...There are some X3/XT models on the way in the form of the announced 2.6 update and the coming model packs...not sure if Super Clean is there or not, but there will be some more options for the platform pretty soon... In the end you probably will not get it exactly like your X3, but dynamic range is better in HD...models have 10x resolution...FX are much higher quality than the XT/X3 FX...So I think you likely could end up in good place...

If modelling managed to replace analog completely, it would be like Syndrome said; "...'everyone' can have powers. 'Everyone' can be super! And when everyone is super...'no one' will be."