Remove One Power Tube

[Melissiah]

Can I remove one el84 on DT25 to cut wattage by 2?

 

Ex: in a mesa dual rectifier if you remove 2 of the 4 6l6 you drop from 100w to 50w. It wasn't cutting the power by half but help a bit to keep volume without exploding my head...

[TheRealZap]

I don't think you can do that... (be happy to be corrected though if i'm wrong)

 

I do think you can run these though: http://www.thetubestore.com/Tubes/EL84-6BQ5-Tube-Types/JJ-EL844-low-power-EL84

not exactly 50% power reduction... more like 25%

[Melissiah]

Yeah I installed em yesterday but bias is weiird I can't go more than 16 and the dt25 need 25 +-3

 

They sound awsome but I'd like a little less power again lol

[MGblade]

had the same problem with my el844's i could go no higher than 12, sounded great anyway

[chrishlp]

Hi Melissiah,

 

I don't think taking one tube out is a good idea, you may cause damage to your amp and that would be an expensive repair! 

 

Further more, if you read the Line 6 Connectivity Guide it tells you that for Class A/B it uses both tubes, so as a minimum you won't be able to use that topology.

 

If you are trying to get low volume power amp sag and distortion, then use the Low Volume setting and edit the parameters.  If you are linking a POD HD, then you have the option to use either normal power or Low Volume with a full amp model, the only difference will be a different response to the Master Volume.

 

Have fun!

[geppert]

There is always the Power Attenuator (Speaker attenuator) route to consider …. few on the forum are fans of LVM.

[Melissiah]

I'm not convince that LVM is still a tube amp so for now I stay away from it. When I tried it all my patchs volumes went crazy.

 

Power attenuator: I tried many of them and every time I feel a big lost in brightness even with some who have a treble pot to compensate.

 

Anyway the next step if I drop volume again is that the speaker won't work enough and the cab won't vibrate so I'll just lower all my patches I guess and forget about natural tube distortion to preserve my ears...

[Rowbi]

As I recall it, LVM is still a tube amp (there's no SS amp in there to use as an alternative), but as part of the volume drop it means there wouldn't be as much power tube distortion. So the amp switches to using full amp models instead of preamp models from DSP.

 

Is there an issue with the sound when on LVM to make you want to try changing tubes to get lower power?

[chrishlp]

The LVM still uses the tube power amp stage but with a reconfigured volume taper. It does not reduce the overall volume of the amp.

 

Use LVM when plugged direct into your DT and it uses full amp modelling. Use LVM with a POD HD connected and you will need to use the full amp modelling (not preamp) to get the right tone. If you then crank the DT master volume you will add Power amp distortion to modelled power amp distortion.

 

A lot of users seem to get confused by the DT amps, treating them as if they are solidstate amps where the level of distortion is set by the gain pot and the mater volume only adjusts overall volume. The DT should be treated as a true valve amp where overall distortion is determined by a combination of preamp and power amp gain.

[MartinDorr]

 

The LVM still uses the tube power amp stage but with a reconfigured volume taper. It does not reduce the overall volume of the amp.

I would be interested where you read or heard that info. Can yo recall?

[chrishlp]

Hi,  I got this from the DT50/DT25 Knowledge Base FAQ on the lIne 6 site.  I've reporduced it below, hope this helps. Have a go at crnking low volume mode with the same model setting and it is still very loud, there is no power amp in the DT25 so it is using the tubes. 

 

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. You therefore are better off using full amp models at low volumes and it does not matter if you are using Normal or LVM as in both the power valves are not working hard enough to get real power amp distortion and sag as well as speaker distortion.

[MartinDorr]

Thanks for pulling this info in and it makes total sense that even in LVM the power amp is used (otherwise there would be nothing coming out of the speaker).

I have more doubts about your second sentence 'It does not reduce the overall volume of the amp'.

The DTs may still get pretty loud if you push them with LVM, but not as loud as if LVM is just off due to the scaled Master Volume.

Appreciate the FAQ extract. I really should reread all the info available from Line 6.

[chrishlp]

Thanks MartinDorr,

 

There is a lot of info in the FAQ and the various manuals, I had to read them all before I started t understand how the amp works.  I am currently playing around with using the POD HD amp model master volume (not the POD MV) to get different tones and dynamics.  I'm finding this a really good way of matching the amp sim to my different guitars.