spaceatl

I like cost effective....I would suggest a Peavey IPR 2000....My cabinets already have Speakons.... Stereo Class D....370 watts @ 8 ohms per channel. weighs 8 lbs....Costs $400....

regardless of what amp you choose, I would say shoot the amp with the NO CAB Option first....This might help find out the flatest amp model....you could opt for the flattest mic you find at this point...probably need to settle on a mic so this doesn't take you a million years as there are so many permutations... Although I have never measured it, The Hiwatt seems the least colorful amp to my ears.... PRE models would be a lot cleaner, but you would likely then figure out that the cab models are a little bit different for the PRE models even though they have the same name...

I have both amps....DT50 112 and a DT25 head/cab... The amp models in both amps change to using FULL models when in LVM mode....So you basically have a typlical POD HD direct out in LVM mode....When LVM mode is OFF, the direct out signal comes from the output transformer on the power amp, along with some cab and mic love and does NOT work on standby...By far LVM off is the better sounding (feeling) option IMHO....But standby direct sounds quite nice too... DT50 did not have this feature of getting direct out in standby....This was added in a firmware update. You pull the Master Volume for LVM on a DT50... DT25 always had this feature...LVM switch is on the back near to the IEC power jack.

I think they turned that feature on in the DT50 with the 2.0 firmware....Originally, DT50s did not have output on the Direct out in standby...

If you want a solid-state amplifier that will reproduce the same fast dynamic transients as a 100 watt tube power amp (typical 4x 6L6), then you need to look for a power amp that is rated 400 watts @ 8 ohms or higher. That's the trick.... Tubes can exceed their rating by upwards of 4 times in fast transients, so if you match that to a solid-state peak rating, you can get closer to the same feel...I say go for a Class D amp....You get high power and they are much lighter weight...

Well, it's an EH12AX7 in the DT50....CHINA 12AX7 in the Spider Valves and DT-25....DT50 was so noisey with the stock EH 12AX7s....I changed them within a couple of days of it's arrival...

I have 6 EH 12AX7s that are all pretty crummy...All are a bit noisy...only two came out of Line 6 gear...Two are OEM from other gear and I bought two on my own...

You mean these guys? Solid-State Tubes....Power tubes are on the way. http://amtelectronics.com/products/warmstone-tubes-solidstate-analogs/12ax7ws-warmstone-12ax7-tubes-solid-state-equivalents/

people have been tweaking bias to their liking for 50 years or more....This is nothing new...sure you can do it...With a conventional amp you run the risk of burning some grid resistors...with a hybrid, you run the risk of damaging other things too...But a tube can fail at anytime and that risk is always there....running hot bias just increases this perceived risk...A tube could blow running cold bias...you never get rid of this risk... but then this amp runs in the "non-linear" regions.... :rolleyes: low bias on an AB tube amp makes your power tubes last longer because they idle cooler....technically, better for any class AB amp because you generate less idle heat...This is true for any class AB tube amplifier...

No worries, my posts are nothing more than my opinion...take them with a grain of salt...Others might have different approaches like lighting incense and scented candles and adjusting the bias in the nude exactly 15 feet from the power source using a 7.25987 Ohm dummy load... You can check plate voltage with the tubes removed...it is a little safer to probe the tube pin from the top of the socket IMHO...

technically, a headphone amplifier is a stereo audio power amplifier....So there is nothing to stop you from connecting your cabinet assuming that you have a stereo cabinet...You would likely hear some sound too...thin sound...if you run it too hard you risk blowing the headphone amp...definitely not something I would recommend... probably better to just get some powered computer speakers or some cans...

Don't bias with a bad tube....Those guidelines are general and nothing but my own approach I take with "most" fixed-bias tube amplifiers...Certainly, one would take out the bad tubes and put in the new ones whilst powered down....These are NOT instructions, just a quick listing of the steps I take...IF you choose to follow them, I make no warranty...You do this at your own risk...and please don't kill yourself...it can certainly be learned...but don't do it using instructions from a forum...electrical safety is PARAMOUNT in this procedure...DT-25 is > 400 volt amp that can kill you dead... Since there is a single bias adjustment in the DT25, a slightly different approach could be warranted...turning down fully clockwise might not be the best idea...better to measure and see what the effect is in very small increments on BOTH tubes...If you are not sure, get a tech to do it for you...

Did you know that EH, JJ, Tungsol, Mullard, Sovteks and other brands are actually branded and re-sold by a company called New Sensor (they own the brands)....Most all New Sensor brands of new Russian tubes are made in the Reflektor factory...I would tend to believe that EH is the better matched pair/quad brand out of the New Sensor brands for power tubes...New Sensor pretty much owns the tube market now...and the Reflektor factory...

Check it with a meter....set meter to resistance....reading shoudl be within an ohm or so of how it's wired (ie: 4 ohm cab might read 3-5 ohms range)....

Here's an idea... Pay a tech to mod your amp...Get test points mounted on the back with a bias pot...Then you can bias your own amp safely...It's literally about $5 worth in parts to do it...One hour of labor is all a mod like that costs...It's a common mod...Then you can change tubes all you like safely and keep your bias in check any time you feel like it...

tube heaters lighting up does not mean anything other than the heaters are working....complete lose of volume with some residual signal makes me think that perhaps you have a bad tube...I would start with the 12AX7s and then try the new power tubes....How old are the tubes?

A always wears tubes faster than AB...if you are running ab mode loud then it doesn't make any difference.

You can power amp in into either DT....The DT50 has a level on the power amp input that acts as a Master...But there is no analog presence like the SVs...The Master on the DT is very different because of the class switching.....

Let's see...I am getting a little confused remembering what the stock speaker was...I have the DT50112 and the DT25 head and cab...I think it was the DT25 cab that had the OEM GH90 in it...DT50 was a Vintage 30...The DT50 412 is crossloaded with these two speakers types....I have to say using the two speakers together does sound pretty good. For my personal taste, I the Vintage 30 is a harsh speaker. I have 4 different ones and I have done all the break in stuff....I think what I really don't like is the Ice Pick peak....To harsh...The GH90 is actually a pretty decent speaker. If I were to choose, I would use a GH90 over a V30...but the reality for me is I don't much like them for myself...GH90, just is not clean enough for me...still has a Celestion flavor to it...just not into that for myself. I have some older Madison 212 cabinets that I use with my combo amps...I have always liked EV12Ls...Years ago I settled on Madison Minstrels...They are about the same rating and the breakup is similar as there not very much...I also have some Madison Symphonies...Similar, but a little lower rating...I have around 2 of each of the Line 6 stock speakers dating back to the AX2. I have some Eminence PA speakers that came out of a Yamaha PA system...They are also a bit like the 12L vibe....I do not have an EV12L right now...I like how they sound, but they are just too heavy for me...Last is the Jenson Jet I mentioned... Speakers are almost always weak links in amplifiers/cabs for me....Sorta like guitar pickups....I like to taylor the input and output source of my tone to my own taste. I can work with anything, but to get the gear to where I really like it, I end up changing quite a few things...

ease up man...I do not know this for sure, but I think actual Line 6 employees cannot give any public DIY advice in regards to technical procedures or IP. He is saying all that he is allowed to say. If what he says scares you, then you should take your amp to a shop...It means you don't know enough yet to do it properly and safely...THESE THINGS CAN KILL YOU....It would not be cool to get killed by your amp while working on it....

The watts (in this case 12) is the maximum dissipation of the tube itself. Max Dissipation of an EL84 is 12 watts (This is on the datasheet) ((Max Dissipation / Plate Voltage) * 0.7) * 1000 = bias mv So you take any tube, find the max dissipation on the datasheet..measure your plate voltage on the amp...plug in the numbers and that gives you the safe bias value to start with for a Class AB tube amp

If this confusing to you, then you might need to read up a little more and perhaps get some assistance from someone who knows how to do it safely....tubes are ALWAYS removed when the amp is powered OFF and the tubes are COOL....Removing the tubes is an easier way to measure the plate voltage in the head...does not apply to the combo...

It might not be clear, but I have the DT-25 head....So there isn't an easy way to get at the back of the tube sockets to measure the plate voltage with the tubes in...It's a logistics thing....Easier for me to yank the tubes, measure the plate voltage, power off and put the tubes back in....The tubes have nothing to do with the plate voltage reading....So certainly the tube are in when you are adjusting bias...On the combo, you can more likely get to the plate socket pin with the tube in and do it all at once...

I like saving weight on the amps too....I tried every speaker you can imagine in my DT50 and DT25 and I found one that is one of the best guitar speakers i have ever heard....and the weight is 4.5 lbs...It might be too clean for some folks, but it does NOT sound like a Neo at all... http://www.jensentone.com/jet_series/tornado_12

So you would not blink if I told you I was going to put the tubes in mineral oil cans and run the plates at a 1000 volts?