Interesting observation about DT25/HD500 Combo

[the29band]

I noticed today that if I switch from patch A to patch B using the HD500 and the patch is already saved on the HD500, it doesn't make any popping noise. However, if I create the same 2 exact patches and save them as a set and then open them using 'Open Set' via EDIT, the switching always creates a popping noise.

 

Is this because the patches are not saved on the POD and it's reading from the EDIT? 

[drschultz]

When I hear to popping sounds from the DT25 it is always from the class mode or topology mode changing.  If you have the same amp setup on two different patches then you should not hear anything. 

When using the EDIT program you have to remember that if you change something ( and not save ) then the EDIT will update the HD500 and the HD500 will update the DT25. 

 

Hope that helps.

[the29band]

I knew about the popping sound because of the class/topology changing. So are you saying that it is NOT normal for the popping sound when changing patches via EDIT (if topology/class are the same)? 

[MartinDorr]

I don't remember popping sounds w/o changing topology/class/tube type, but I do know that changing the preamp on my DT25 (while keeping topology/class/tube same) will change some additional behaviors in the power amp stage. For one, it seems the that the Presence setting will have an impact and that different preamps select different baseline attenuation levels for the power amp stage.

 

You can check this out by putting the a preamp into path A and nothing into path B. Then set the mixer of path A to Mute and Path B to 0dB center. Now you should hear a pure power amp stage amplification of your input signal going through the HD w/o any processing through path B.

 

Start with a Type I, A/B, Pentode preamp. Chaning any of the Drive, Bass, Mid, Trebble, Channel Volume dials will have no effect, but Presence does. Raises your level about 3dB and changes frequency content, i.e., Presence is used in the power amp stage.

 

Now try different Type I, A/B preamps. You will find output level changes of about 8dB from the lowest (I think FlipTop) to the higest (Hiway). I have not dug deeper into whether after you adjust for the volume differences (via mixer) that there may also be significant tone changes. I'd guess at least minor changes because the RMS level do not track the peak level differences, i.e., there is some harmonic content added or removed when selecting to different preamps. But remeber, this experimental patch does not use any preamp model. Neither in the HD500 nor in the DT25.

 

Back to the popping. I don't remeber hearing poping when I experimented with all the above, but I may just not remember and things do change in the DT power amp stage even if you stay with a fixed class/topology when you change preamps. Also, I was using the HD to experiment and not the edit SW.

 

I may be able to dig up an old list of measurements and can post level differences if you are interrested. Not sure whether that translates between DTs as I guess tubes and biasing may have impact on the magnitude of differences.

 

Martin

[stumblinman]

I remember reading somewhere that changing patches on the 500 while connected to Edit causes very slow patch change response times. This may affect the power section of the DT in a negative way if it is receiving class and topology information in a delayed fashion. I never use Edit as I find it much easier to work with the Pod itself so I can't give firsthand experience on that. I usually use the same topology for all my patches just to minimize the chance for unwanted noises.

 

In short: I'm guessing it's a communication delay issue.

[the29band]

Thanks, that's what I was thinking too. Either way, as long as the popping doesn't occur while changing patches from the POD because in a live situation, there will be no EDIT.