Community: Message List - DT50 high noise floor (hiss) solutions

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Sat, 08 Dec 2012 05:38:23 GMT

Glad that you are enjoying the amp. It is great!

I thought I would share with you the recording post pream tube change to a TungSol one. Conditions of the recording were the same (Typology III, Class A, Pentode, Gain at 20%, Volume at 50%, Master pulled out at 50%, recorded with a crap cheap computer mic). I didn't trim the beggining of the audio file so you guys can hear how quiet it is even without playing.

Let me know what you think.

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Fri, 07 Dec 2012 06:06:09 GMT

Hi,

I just got my DT50 212. I noticed the the noise issue. #3 is the louder. When nothing is connected to the amp the noise is higher. When the HD500 is connected the noise is reduced. I've updated the firmware and the noise was reduced a little more. it sill there but is better now (3 is still the noiser). At very low gain (practically listen the string from my electric guitar) the noise kind of bother me, but i just play at that volumne when my little one are sleeping. With a no so low volumne, the noise is ok, even for quiet riffs is ok. Using my HD500, some of the effects cut any remain noise. The only thing that having crazy is when I change a present from high to low gain in my pod it makes me jump from my stool (that happened also with my normal amps, but this is worst). Overall, I'm happy with the quality and sound and the noise doesn't bother me too much to don't recommend it (I'm not so picky)

So summary: I think I reduced some noise with the update of the firmware and with pod in low gain effects (the high gain covers the noise, so is not a problem ).

I'm not a tube expert, it's just my experience.

BTW, the audio you uploaded Hugo, sounds louder than my noise in possition #3.

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Thu, 29 Nov 2012 04:17:47 GMT

Sorry that replacing the 12AX7s did not make a difference to you. I have only tried with the TungSol ones so I can not confirm how noisy are the Mesa ones compared to the EH originals. Let us know how the JJ's go.

On my case it was a big difference. Still not quiet by any standards, but it is at least usable. Meanwhile my support ticket got escalated today... Not sure what that means, but maybe Line 6 is looking into it... fingers crossed....

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Tue, 27 Nov 2012 15:07:31 GMT

Just thought that I would reply with my findings:

I have had a DT50 now for a couple of weeks, and noticed, like many of you, that the noise floor was quite high.

Based on my readings, I replaced the 12AX7's with Mesa SP12AX7's, and while it did take some of the noise out, it was not a huge difference.

I am going to try some JJ Gold's, and will reply back with those findings, but unfortunately, not a huge difference with the SP12AX7's .

Like many: voicing 3 is the most noisy.

NOTE: I have also updated to 2.0 (reflashed a couple of times just to be sure), as well as try the factory reset thing. Now, I find that it is usable, but my other tube amps are more quiet that this thing. But it really does sound great, really great in fact. Just too bad about the noise.

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Thu, 22 Nov 2012 11:59:09 GMT

Great sugestion. Another thing that people can try...

Meanwhile I received a pair of TungSol 12AX7s and unfortunately one of them is microphonic. BUT here is the interesting thing. I used the other one to replace one of the original tubes and the noise was cut by half at least!! So definitely something for people having this issue to try. You should have spare tubes anyway so you don't lose anything by trying some new tubes out!.

I do have to confirm that as warned by Line6 suppor there was a loss in overall volume of about 5% and the tone changed ever so slightly (for the better for me since it gained clarity)..

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Wed, 21 Nov 2012 11:48:32 GMT

I manage to decrease the hiss of Voicing III on my DT50 212 Combo. I reseted (I don't know if this is the right word for it) the DT50 and that did the trick. Voicing III is still the loudest one, but much quieter now.

Here's what i did:

1. Push DT50/25 voicing knob DOWN. Now, at the same time push the Pentode/Triode knob UP. Keep them pushed at these positions.

2. Now Power up the DT50/25 and keep the knobs pushed. First all the lights on DT50/25 will be on, then some of them will go off.

3. After view seconds Channel A, Triode, Voicing I and Class A/B lights will go on.

4. Release the knobs. DT50/25 has been reseted to factory setup.

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Tue, 20 Nov 2012 07:16:01 GMT

Update from my ticket with Line6 support:

Hi,

I can understand that hearing the noise floor change on the amp can be a bit jarring at first but I really don't hear anything from the recording that leads me to believe anything is wrong with the amp.

For instance high gain amps such as the Mesa Dual rectifier and even the Bogner Alchemist that we used to manufacture have a similar noise floor. It's a byproduct of the power and preamp tubes being pushed hard to produce the gain levels in the amplifiers.

Understand I am not trying to be difficult, I would just hate to send you to a tech that will charge a fee to look at the amp when I don't believe anything is wrong.

People on the forums have commented but in order to do the things that the DT50 does there is going to be a drastic difference in noise floor in some instances. This is not really something that can be overcome on the technical side. In short, tubes hiss.

You can hear this on many modern metal recordings:

http://www.youtube.com/watch?v=eebzVpqm7-s&feature=related

This song was recorded with a Dual Rectifier check out the noise floor at the first of the song.

Definitely noticeable when not playing. On a lot of records this is gated or trimmed out in the recording software but this is a good example of a raw recording of this type of amp.

You could put different power tubes in the amp but if you found a quieter set you are going to loose some gain and the amp will not have the same kind of breakup.

Thanks,

David

And my reply:

Hi David,

Thank you for your reply and for looking into this.

I understand your point of about how different settings (in this case changing the amount of feedback that goes into the power amp valves) is going to have an effect on the amount of noise. But if the amount of noise would be related to how hard we are pushing the valves, shouldn't it increase/decrease with increasing/decreasing the volume/gain?

Also since the DT50 with the master volume knob pulled out and turned low is basically just using the power tubes to "warm" up the tone, they shouldn't be pushed hard enough on this mode to create the hiss.

I am no audiophile in the sense that I can't almost distinguish the tone differences between two valve brands of the same type. I listened to the link you gave me and I swear I can't almost hear any hiss.

To put this in perspective to you, if I am having a normal conversation in my room with somebody and I turn the amp on on type III (again with all controls at 0 and nothing connected to the amp) we have to raise our voices to continue! It is literally like listening to an old FM radio tuned in-between stations.

If replacing the valves with a less noisier brand will reduce the noise, even losing some of the gain/breakage when pushed/tone might be a solution, I will give it a try. I need spares anyway... I have a pair of TungSol 12AX7s on the way and will get a pair of EL34s to see if there is any difference.

I know you are not trying to be difficult and believe me I am not also. As I said I love the sound and the flexibility of the amp. If not for the noise it would be the perfect amp and I would recommend it to anybody.

Hopefully we can find a workaround and me and a lot of other users can be happy.

Cheers,

Hugo Fonseca

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Sat, 17 Nov 2012 11:48:53 GMT

Troubleshooting basics:

Here is a list of basic traoubleshooting tips that might fix your specific noise issues with the unit.

1 - Reinstall firmware / Install the latest firmware / Install a different vesrion of the firmware.

This are all possible solutions to your problem. The DT series amps do a lot processing of the sound in software. They "model" the sounds of the amps in this process, including some noise properties. Trying different versions of the firmware or reinstalling a "faulty" one might have some positive impact on the noise level.

2 - Reseat the valves / Swap valve positions / Clean valve contacts

During transport your amp is shaken all over. It is possible that your amps's valves have rattled out of position and they are not seated properly. Removing them and placing them back on (after clenaing the contact with some electronic contact cleaner) might solve your issue.

No two valves (tubes) are the same, no mather how good is quality control. It is just the nature of they are made. Plus they all have the tendency to become microphonic with usage. If one of your valves is noisier than the other, swapping their position might have some positive effect on the overall noise level.

3 - Change valves / Rebias the power amp

Again your tubes might be faulty or they might just be noisy. Different brands of tubes have different noise levels (among all the other different properties), so changing valves might fix your noise problems. There are a few reports of fixed hiss problems by swapping the "preamp" (not really preamp) tubes for TungSol 12AX7's. You should always keep some spare valves, so it is worth a shot.

If you swap your power amp tubes (EL34's) it is always good practice to rebias your power amp section. Probably a good idea to pay an amp tech to do it unless you know what your doing. While it is there why don't ask hime if he has any ideas about reducing the noise levels. Maybe he will come up with something and you can share it with the community...

4 - Try a power conditioner / Voltage regulator

Unfortunately most of our hoses's electrical lines are terrible. That is a simple fact.

Test for ground in your wall socket. If your ground is not properly connected, you will have a lot of hum.

Changes in current/voltage will prevent your amp from performing at its best. Also spikes might even burn the fuse out in extreme events. A power conditioner and/or a voltage regulator will have prevent this and keep a nice steady feed to your amp. This may also improve noise issues.

5 - If the noise only happens when a guitar/pedals/effects racks/whatever are connected the problem is in your chain and not in the amp. Start eliminating things from the chain one at a time until you find the problem.

I think this will cover most common troubleshooting scenarios. If after doing any of this things your noise went away let us know so others can try it also.

Good luck.

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Fri, 16 Nov 2012 13:03:28 GMT

I hear the voices of the dead thru mine. Guess I better not do what they keep telling me to do, tho, huh?

Re: DT50 high noise floor (hiss) solutions

support@line6.com — Fri, 16 Nov 2012 11:38:56 GMT

Well, from reading the other threads, some users have had some success resolving the issue one way or another. Hopefully we can narrow down a solution to the issue, or/and Line6 can help us out providing a workaround/fix.

It is an amazing sounding amp that is a shame that something like this prevent it from being used in low volume/mic'd scenarios.

I am hoping that the rest of the DT owners will join their voices here so together we can work this out and maybe put some pressure to Line6. Unfortunately some of the previous owners of the amp were not so persistent and have already given up on it...