DT50 Master Volume & Noise Floor

[sorcerer532]

I'm wondering if the master volume on my DT50 is behaving normally. I am using an EMG81 active pickup plugged into the LOW input.

 

I have the amp on topology IV and have the channel volume all the way up.

 

When I slowly increase the master volume, I have to bring it up a bit before I suddenly get a loud signal. Before that threshold there is no signal (relative silence with no guitar signal).

 

I turn the channel volume down and noticed the curve of the master volume's behavior is somewhat the same. I take it past the same (or very close) threshold and suddenly there is a healthy dose of volume.

 

Is that normal behavior for everybody else's amp?

[psarkissian]

In topology IV,... sounds about right. It is one of the more loud, higher gain topologies.

Check the manuals for info on gain topologies.

 

[sorcerer532]

47 minutes ago, psarkissian said:

In topology IV,... sounds about right. It is one of the more loud, higher gain topologies.

Check the manuals for info on gain topologies.

 

Thanks!

[sorcerer532]

8 hours ago, psarkissian said:

In topology IV,... sounds about right. It is one of the more loud, higher gain topologies.

Check the manuals for info on gain topologies.

 

psarkissian--another question--I've noticed that the noise floor on the amp is really quite loud, even when nothing is connected to either of the inputs on the front panel.

 

The level of the noise seems to be dependent on topology. 

 

I read one review that mentioned this behavior, but I find myself wondering if it might be time for new tubes.

 

...because the level of the noise seems dependent on topology, does it mean it might be coming from the power section?

 

Note that I have not put a noise gate before the amp or in the effects loop yet*

[psarkissian]

With higher gain loops being engaged, all amplitudes are higher, including the noise.

Gain topologies and and the digital processing are designed to bring out the classic tube

sounds of the 1960's and 70's tube amps.

 

And the DT-50 212 having two 12" speakers, everything is louder than the DT-50 112, with 

one 12" speaker. One of the things that Steve Howe (of Yes) and Roland Orzabal (Tears For Fears)

like about the DT-50 212. Had the pleasure of servicing both of their amps (each having two of them).

 

Rheinhold Bogner's tube amp designs are also goes back to that earlier time of tube amp.

It's what Bogner is known for. Interesting fellow with some really good tube amp designs.

 

New Tubes? How long has it been since the last tube replacement?

 

Check the recommendations for how often to change them out and which tubes to use.

It's more than just tube swap and bias. There is a procedure for the tech to do,... bias, warm up,

signal tests, let it run, then post test bias. So any tube replacement needs to be done by a

Line 6 authorized service centers to be done correctly.

 

[sorcerer532]

1 hour ago, psarkissian said:

New Tubes? How long has it been since the last tube replacement?

 

I have only had the amp for a few days and I really don't have any type of tube history.

 

Both the preamp and power tubes are the Electro-Harmonix branded EH tubes. 

 

I would have to take a closer look to verify, but the previous owner told me that the EL34's are marked 10 02 and 09 11, while the two 12AX7's are marked 09 07. I'm not sure if those markings are dates.

 

Here are pictures I received of the tubes:

[psarkissian]

Specified tubes. Very good.

The markings are the manufacture date, not how long they have been used.

 

Those look okay for now, but the inner coating (getter flesh) is looking a bit dark.

Might want to take it to a Line 6 authorized service center for a check-up.