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DT50/DT25: FAQ

dt25 dt50 topology dt_faq amplifier bogner tube pentode triode midi

Please read through the DT50/DT25 Terminology FAQ first, to familiarize yourself with the terms that will be referenced here.

Q: Are there any presets on the DT50/DT25 amplifier in the manner of previous Line 6 amps?
A: No. The DT50/DT25 behaves like a traditional amp where the user simply dials in a tone to the WYSIWYG (what you see is what you get) functionality.

Q: Are the DT50/DT25 amplifiers Mono(phonic)?
A: As with most tube amplifiers, yes.

Q: Which type of amp modeling is using with the DT50/DT25?
A: Line 6's newest HD amp models (same as our new POD HD).

Q: How does the power amp tubes contribute to the DT50/DT25's sound?
A: The EL34's (DT50) or EL84's (DT25) are the main source of distortion in the amp. The guitar signal is actually being amplified at every progressive stage in the circuit, but the power tubes are the first to truly "clip" and provide the distortion that most tube amp devotees desire.

Q: How does the modeling of the DT50/DT25 contribute to the overall tone?
A: In the DT50/DT25's "normal mode", the modeling performs the function of the preamp: mating the digital preamp with the analog power amp so the whole system creates the sound of the amp modeled. This is different than our previous Spider Valve amps, where we modelled the entire amp model (pre-amp and power amp) and then fed that signal through the output tube power section.

In "low power mode" (pulling the master volume switch out on the DT50 or on the DT25 flipping the switch on the back panel), the digital modeling section will assume duties for the power amp section and the Master Volume has been scaled so that you can have the sound of a driven power amp at lower monitoring volume levels. If you turn the master volume knob all the way up in this mode, you will have Spider Valve-like tones behavior (where the pre and power amp software modeling signal is pushing the EL34 or EL84 tubes).

In both Normal and Low Power modes, cabinet modeling is applied to the output signal fed to the power tubes. When using a POD HD device connected via L6 Link, you must use the default cabinet model that is recalled on the POD HD 'pre' amp model when using the L6 Link connection with the DT amp to get the same type of sound as using the DT amplifier by itself with the same amp model.

Lastly, when using Low Volume Mode on the DT amp with a POD HD connected via L6 Link, the sound of a 'Pre' amp model selected on the POD preset will sound slightly different if an identical amp model is selected on the DT amplifier (on Channel B ). This is because when using the Low Volume Mode on the DT amp with L6 Link, Channel A on the DT amp with the POD modeling is still using the just the PRE amp model with the scaled Master Volume knob, whereas Channel B on the DT amp uses the preamp AND power amp modeling with the scaled Master Volume. The inclusion of the power modeling is what makes it sound differently.
Q: What is the difference between the DT25 and the DT50 amplifier?
A: The DT25 operates at 25 watts maximum output using two (2) EL84 power tubes vs. the EL34's found in our DT50's. Otherwise, it is essentially the same as its big-brother, the DT50. For more info, please check the new product page for the DT25 here.

DT50/DT25 Voicings Switch

I – Negative Feedback Loop (NFL) setting is high; channel control behavior much like that of a West Coast American amp of the 1960’s.
Recommended settings: Class AB & Pentode.

II – NFL is medium; channel control behavior much like that of a classic British amp of the 1960’s known for it's "glassy" yet warm tones.
Recommended settings: Class AB & Pentode.

III – Zero Negative Feedback Loop operation (a very open/dynamic feeling amp); channel control behavior much like that of a “chime-like toned” British amp of the 1960’s.
Recommended settings: Class A & Pentode (clean) or switch to Triode (for rounder, more vintage feel).

IV – NFL is low in value, with an added low frequency resonance ideally suited for modern high-gain voicing; channel control behavior much like that of a more recent West Coast American amp of the 1990's.
Recommended settings: Class AB & Pentode.

Class A & Class AB Switch

Class A: Cathode biased. Provides the player with more dynamic with touch sensitivity. DT50 operates at 25 watts. DT25 operates at 10 watts.

Class AB: Fixed biased. Provides greater headroom and power than Class A. DT50 operates at 50 watts. DT25 operates at 25 watts.

Pentode & Triode Switch

Pentode: Clearer tone and more headroom.

Triode: Rounder tone, less output and more vintage feel.

L6 Link

L6 LINK is a proprietary Digital Audio connection developed for exclusive connection between the POD HD series modeling processors and the DT50/DT25 amplifier(s). Do NOT connect any other sort of analog audio device that appears to have a standard 3-pin (XLR) connector to the L6 LINK, as damage will occur.

Connect a digital XLR cable (AES/EBU cable) from the POD HD L6 LINK jack directly to the DT amp’s L6 LINK IN jack. Most XLR cables should provide sufficient performance, but use a digital XLR (AES/EBU) cable for best performance and signal to noise ratio.


DT50 Specifications
DT25 Specifications

Q: Is there a chart for the amp models of the DT series amps and the POD HD series?
A: Yes, there is a .pdf document with this information here.

*Please note, most of the amp models on the DT series are only accessible via MIDI. Please reference the following document for information on accessing these models:

Using MIDI to Change Amp Settings on the DT50/DT25 Amplifiers

Q: What speakers are used the DT50/DT25 amps?
A: DT50/DT25 112 Combo has the Celestion custom G12H90 12” speaker. DT50 212 Combo has a Celestion custom G12H90 12” and a Celestion Vintage 30 12” speaker.

Q: What tubes ship in the DT50/DT25 amps?

DT50: Electro-Harmonix 12AX7 preamps tubes (2) and Electro-Harmonix EL34 power tubes (2).

DT25: Chinese-branded 12AX7 preamp tube (1) and Sovtek EL84 power tubes (2).

Q: What is the Bias Spec on the DT50's EL34 power tubes?
A: 36 mV +/- 1 mV.

Q: What is the Bias Spec on the DT25's EL84 power tubes?
A: 25 mV +/- 3 mV.

Q: What Line 6 controllers work with the DT50/DT25?
A: Any of the POD HD series units. They utilize the new proprietary L6 Link (3-pin) digital connection to control amp topology settings in Channel A to whatever parameters are set in the active POD HD patch.

There is a jack labelled for "Footswitch" on the back of the amp to allow for switching between Channel A and B. Please use a "tip-sleeve" (mono 1/4") latching-type footswitch to use this feature.

DT50 & POD HD Connectivity Video

Q: Is there a headphone output on the DT50/DT25 series?
A: No.

Q: Is there a bias switch to change the power tubes to 6L6’s or other tube types?
A: No, the DT50/DT25 series do not offer bias-switchable options and were designed to operate with the EL34 (DT50) or EL84 (DT25) power output tubes.

Q: Can I run my DT50/DT25 without a speaker load?
A: No! You should always run a tube amplifier with a speaker load present. Please follow the properly load connection requirements as silkscreened on the back of the amplifier chassis.

Q: Will installing casters on a DT50/DT25 112 or 212 combo chassis void my warranty?
A: No, correctly installed casters will not void the warranty. However, if you are not 100% sure on how to correctly install casters, please take your amp to a qualified amp/service technician and have them install the hardware. We do NOT cover damage caused to the amplifier from an incorrect installation!

*** Here is a link to one of our Forum Members (MDinice) who was kind enough to share a template for Ernie Ball type casters: http://line6.com/com.../57744?tstart=0 (the template is also available at the bottom of this document). Known-Issues
12AX7 Preamp Tube Swapping: If you decide to swap out different 12AX7 preamp tubes, do NOT use anything labeled “LP” (Long Plate) for the first preamp tube stage (labeled as V3), as “LP” labeled tubes are extremely microphonic.

Q: How do I control the v2.0 update features of the DT25/DT50 amplifier using MIDI?
A: We have created a document to help with sending MIDI to your DT amplifier to control the various additional features of the v2.0 update. Please see the following document for these instructions:

Using MIDI to Change Amp Settings on the DT50/DT25 Amplifiers

Also, here is a link with information on troubleshooting tube amplifiers:
Troubleshooting Your Tube Amp