Dt25 Lost Signficant Volume

[grandinq]

Hi everyone,

 

I went to jam with some friends today, and I really wanted to show off my cool DT25 to a friend of mine.  However, things turned into a nightmare.  While my tones out of the DT25 sounded accurate, there was hardly any volume.  Usually when I jam in the basement with friends, I keep the volume at about 3.  Today I had it at 8 and the other guys said they couldn't hear me (and I couldn't hear myself well either).  I had never turned this thing up to 8 in my life, as I thought it would melt my ears.

 

My first thought was that it had somehow got into Low Volume Mode, but that was not the case.

 

So something is very wrong here.  I use a Pod HD500 with it, but it's not the Pod, as I tried just plugging a guitar straight into the DT25 and the low volume issue was still there.  

 

Does anyone know what this could be?  I don't move it much, and I've only owned it since March, thought I bought it second hand.  Still, it's played like a dream up until now.  I'm thinking I maybe have to do a ticket or something.

 

Thanks for any advice!

[Brazzy]

How much time do you have on it? Maybe the 12AX7 in there is shot out.

[grandinq]

How much time do you have on it? Maybe the 12AX7 in there is shot out.

[grandinq]

By "how much time" I have on it, do you mean how much use the amp has had? It is about a year old and I have had it for 8 months. I have on average played it about once or twice a week.

 

If a tube has gone bad, how would I know whether it is the 12ax7 or the el34 tubes?

[Brazzy]

I take it the tubes life is determined by the amount of time put on them, also how hot they run has a detrimental affect. I read in the forum archives that someone with a DT25 had this problem and it was that 12AX7 tube, but they went and did all the tubes. I'm gearing up to be able to service the tubes in my DT50 Head by getting a Bias testing tool and spare tubes. It was suggested that I get a Quartet of power tubes and set the amp up to run them so in case I have a problem I should be able to just exchange power tubes and the bias would ok, but I'm going to check that out later when I finally get what I need. Also I need to have spare fuses. These are fairly easy things to fix on the fly if you get yourself set-up right. When you run an amp with tubes in it you have to expect to do maintenance. I also heard that after about 2 years expect tube failures although I don't know how many hours of actual playing causes them to deteriorate and then there's the chance of the tube just being bad quality.

 

I forgot to mention you may need to re-flash the firmware. Also you could try resetting it. See the picture attached.

 

 

 

DT25/DT50 FIRMWARE INSTALLATION INSTRUCTIONS

NEEDED:

• A MIDI interface that connects to your computer via USB (download the current Driver for it if you don't have it installed)
• 2 MIDI cables (or a MIDI interface such as the M-Audio Uno that comes with attached MIDI cables)

NOTE: Line 6 recommends a name brand USB to MIDI interface produced by an audio company that supports/updates their drivers. Good choices include: M-Audio, Edirol, E-Mu and MOTU. These interfaces have proven to be more robust and reliable when it comes to large MIDI transfers such as the DT25 and DT50 update.

• Latest version of Line 6 Monkey installed. Download and install the Line 6 Monkey software here.

Procedure

• Connect your MIDI interface to your computer via USB cable.
• Connect the DT25/DT50 MIDI Out to your MIDI interface In, and connect the DT25/DT50 MIDI In to your MIDI interface Out.
• Launch the Line 6 Monkey with the DT25/DT50 connected via the MIDI interface and powered on.
• Select the Flash Memory line item and click the Update Selection button to install the flash memory update into the DT25/DT50.
• The device will receive the firmware data and the unit will be updated to the latest Firmware.

***If the firmware update fails and you are having trouble reconnecting to Line 6 Monkey, please try putting the unit into SAFE MODE before starting up and connecting to the Line 6 Monkey software. To do this, hold the channel select switch down to 'Channel B' and power on the DT amplifier while holding this switch down. Let go of the switch after 10 seconds or so, then re-start Line 6 Monkey and follow the steps above to update/re-install the flash memory.                                                                                                                                                                                                                                                                                                                                                                                                        

[leegoodrick]

Try taking a 1/4 out from the pod and setting it to output line level and feed this into the effect return of your dt25 (the master volume on your POD should now control the overall volume (effectively bypassing the pre-amp section of the DT25). If the volume seems ok then its sounds like the pre-amp part of the DT25 is faulty and the power amp and the valves are ok. Try plugging the guitar directly into the effect return of the DT25, turning the volume knob on the guitar down first, and slowly turning it up just to verify that the power amp is working ok.

 

I had this problem and despite being returned to Line 6 service twice for repair, it was never resolved until they gave me a replacement and it's been trouble-free ever since.

[Brazzy]

That sounds like a good idea leegoodrick, but isn't the preamp modeled on the DT25 and DT50? I mean I keep hearing that all the tubes in these things are power section and the preamp section is modeled.

[grandinq]

 

Brazzy, I thought the same thing about the preamp but according to this specs page there is a 12ax7 in the preamp;

 

http://line6.com/dt25/specs.html

 

I will give this a try.

[radatats]

the 12ax7 is NOT in the preamp, it is the phase inverter for the power amp and is almost certainly not the problem.  

 

Try leegoodrick's idea with guitar into FX return and see what happens.  If it is still weak output, it is in the power amp, probably a power tube.  If that sounds OK then go to the amp input and try again.  Cycle through both channels A and B and all 4 topologies for each channel.  

 

Do those things and let us know what happens.

[Brazzy]

Here's an example of what I was reading: Check out the rest of the thread if ya have time. Please don't misunderstand me I really like the DT50 & DT25, It really has great tones. At least I'm having liking it. I also know eventually I will have to work on it to keep it sounding good.

 

Re: DT25 preamp tube
by gareee on 2011-12-28 13:59:06

I'm not understanding this.  Is the 12AX7 preamp tube not part of the preamp, since the preamp is modeled?

Is the distortion all based on modeling? In the models on the edit software, you create the distortion using the preamps. I assume that any distortion that is created comes from this modeling stage - then is fed through some  tubes in difference configurations based on the topology setting.  So  this topology thing is just a tube circuit to feed the preamp models through, right? As in, it's not creating the distortion, just colouring it in a consistent pattern for each topology, colouring clean sounds and distorted sounds in the same way.

Strange beast, this is.  I'm planning on getting one, but would like to understand it before making the purchase.  It would be nice if there were a way to generate tube-based distortion.

 

Re: DT25 preamp tube
by hollis1003 on 2011-12-29 05:33:22

Seems like you are understanding it correctly.  Marshall has a series of amps that do the same thing but all in the amp itself.  It's called the JMD series:

http://marshallamps.com/product_range.asp?productRangeId=31

Theyhave finally discovered that they can better model the preamp section of an amp than the power amp section.

Anyway, I have been using the POD HD 500 with a DT-50 head and a Line 6 4x12 with V30s for a few months now and I love it.  I used to have the HD147 (all digital with a solid state power amp) and it was OK but nothing like the DT-50.  The power amp section really makes a difference and the POD HD technology is very good, much better than the last generation.

The only thing I can say is to try it out for yourself.  If there is no store in your area ask for members of this forum in your area that have one.  I would let people test out my set up if they were interested.

 

Re: DT25 preamp tube
by Line6Don on 2012-01-04 09:59:42

+1 to hollis1003.

The answers are on the threads that he provided to you above:

"The two 12AX7/ECC83  tubes are not pre-amp tubes in the traditional sense.  They are both part of the power amp section. 

One boosts the overall level of the pre-amp output to drive the EL34's and the other is used as an inverter."

Therefore the DT series amp include 4 different preamp models to choose from, when using in combination with one our HD series POD's, more preamp models from the POD can be used in place of the 4 internal preamp models of the DT.

[MartinDorr]

I am a little confused about the point of your quotes (the second 2 do not apply to DT25s). I have a DT25 and there is only 1 12AX7 and it serves as a phase inverter and not as a preamp stage.

I believe in the DT50 there are 2 of those tubes and one serves the same purpose while the other one is used as a boost stage in the poweramp section (the boost does not exist in the DT25 and there is no MIDI control for it either).

In regard to the source of amp generated distortion you need to consider the amp type. Some get their distortion from the preamp section and others do get it from the power amp section. In other words, some will get it from the modelled preamp and others from the reamp power tube amp section. I believe Twins and Lux's get it from the preamp and they tend to sound pretty harsh when driven hard for this reason. Note, the reason is the preamp distortion and not the fact that the preamp is modeled. Haven't played much with real Fender amps, but I believe they do the same thing (modelled or not).

As far as the original problem goes I think the provided advice should help pinpointing the source of the trouble. Unless grandinq hit the LVM switch by accident something seems broke.

[Brazzy]

The point I'm trying to make is that by better understanding what other people have already dealt with it makes easier for me/us to work on my own equipment when it malfunctions, which it (devices) will eventually. This idea has saved me $1000's over a period of time (my life). I was taught when I was very young that by learning from other peoples mistakes I would make fewer mistakes. This does indeed work as by making fewer mistakes advances are made quicker. The forum here and the archives are for that very purpose, take advantage of them. We all know you can't believe everything you read on the internet, but when smart people talk they make sense.

 

The point of my previous post's is to help get the thought processes going, which raises questions which leads to better understanding and eventually an answer.

 

Sorry for the confusion, I probably should have added part of this thread to the previous threads or maybe I'll add part of it to my signature.

[grandinq]

Update!

 

It seems to be working again.

 

I first cycled through each channel and each topology within each channel; all low in volume.

 

I did a rest, and I updated the flash memory to 2.0, and now it seems restored, although in stand alone mode, Topology I sounds not only quiet (I know it's the quietest of the four) but it also sounds like there's more overdrive/gain in it.  Maybe it defaulted to one of the other models present in the 2.0?

 

Great troubleshooting ideas on here; I will make a note of them (using the fx return etc.)

 

I just wish I knew what had gone wrong in the first place.  I know there was a threat awhile ago on this, but the whole experience just gave me this really helpless feeling that when something digital goes wrong, it's hard to fix.  I feel like I lucked out, but I also feel like I was **this** close to having a useless, expensive thing on my hands.

 

Thanks again for all the tips -- these are great forums!

[radatats]

Glad it worked!  good job... :)

[Brazzy]

Great, Thanks for the feedback. Maybe you had a blip in the power and it messed with the programming. Whatever happened move on and chalk off as another learning experience.

[TheRealZap]

late to the party... but a quick reset shall you need it... is to pinch the topo switch down and the pentode switch up while powering on, hold while lights flash, you should be able to tell when to release.

this will of course lose any of the topo settings you changed etc and restore the amp to its defaults.

[nikoniablue]

Uberguru - does a reset restore the original v1 firmware or just reset the presets to the original ones?   Thanks in advance

[Brazzy]

Reset, as TheRealZap stated above, does not restore firmware to V1. It only resets to the factory presets. I do resets regularly, lol.

[nikoniablue]

thanks - sorry - should have spotted it.  New to this forum (though older hand on HD500 and Variax).  Cheers.

[saTa]

I have the same problem and resets don't fix it. Used to have it at 3 in the rehearsal room and couldn't hear myself at 10 today. However, I did install the new 2.20 HD500 flash memory and am thinking that that might have messed it up as well. Will do some more testing tomorrow. :(