martin manning wrote: ↑Wed Jan 15, 2020 11:05 am
What I'm suggesting above is to rotate the pan 90 degrees in-plane (keeping it flat) so that just the output end is inside the head box. Most of it will be sticking out the back. This would be the equivalent of rotating the PT 90 degrees in plane.
Hi Martin, thanks, yes this is exactly one of the tests I did, placing the pan 90degrees to the PT (flat as it usually is inside the box, with half of it sticking our from the front as I removed the grill) with the output (red) side underneath the PT I have a lot of hum, if I place the input side (black) I have hum but less strong, If I place it vertical as of it was my grill cloths I have no hum at all.
martin manning wrote: ↑Wed Jan 15, 2020 11:05 am
What I'm suggesting above is to rotate the pan 90 degrees in-plane (keeping it flat) so that just the output end is inside the head box. Most of it will be sticking out the back. This would be the equivalent of rotating the PT 90 degrees in plane.
Hi Martin, thanks, yes this is exactly one of the tests I did, placing the pan 90degrees to the PT (flat as it usually is inside the box, with half of it sticking our from the front as I removed the grill) with the output (red) side underneath the PT I have a lot of hum, if I place the input side (black) I have hum but less strong, If I place it vertical as of it was my grill cloths I have no hum at all.
The Two Rock is laydown similar to mine.
then can't you screw it to the front panel then? I think fender used to do that in their heads. if your front panel has cut outs and the pan doesn't look good there then make a new solid one like the Dumble amp heads.
martin manning wrote: ↑Wed Jan 15, 2020 11:05 am
What I'm suggesting above is to rotate the pan 90 degrees in-plane (keeping it flat) so that just the output end is inside the head box. Most of it will be sticking out the back. This would be the equivalent of rotating the PT 90 degrees in plane.
Hi Martin, thanks, yes this is exactly one of the tests I did, placing the pan 90degrees to the PT (flat as it usually is inside the box, with half of it sticking our from the front as I removed the grill) with the output (red) side underneath the PT I have a lot of hum, if I place the input side (black) I have hum but less strong, If I place it vertical as of it was my grill cloths I have no hum at all.
The Two Rock is laydown similar to mine.
then can't you screw it to the front panel then? I think fender used to do that in their heads. if your front panel has cut outs and the pan doesn't look good there then make a new solid one like the Dumble amp heads.
M
I tried Marcus, but unfortunately there is no space. The Pan is too deep and touches the transformers. The gap between the grill and the transformers is very thin.
So to recap:
Stand up power transformer with a horizontal pan or;
Lay down transformer with a vertical pan.
Mumetal or other shielding doesn’t really help, so construction is the way to go.
FWIW: I have zero hum issues in my amp with standup pt and horizontal pan.
FWIW 2: I have read more comments about reverb hum in Two Rock amps. Don’t remember the source of these comments anymore though.
Now, how will you solve your hum problem? Combo? New end bells from classic tone to mount your pt upright? Outboard tank? Remounting the pt and Covering the existing hole in the chassis with a small piece of metal seems like the obvious solution to me, but that’s me.
also, can you hear your power transformer hum when it's on? I've used hammond transformers for my first build and you could hear them hum when they were on. When I got my first InMadOut transformers i thought they were broken because they were competently silent.
norburybrook wrote: ↑Wed Jan 15, 2020 2:59 pm
also, can you hear your power transformer hum when it's on? I've used hammond transformers for my first build and you could hear them hum when they were on. When I got my first InMadOut transformers i thought they were broken because they were competently silent.
Just a thought.
M
I use classic tone and indeed can hear a hum when it's on, on both my 50W and my 100W.
Point taken, will surely look at their products next time around
rootz wrote: ↑Wed Jan 15, 2020 12:44 pm
So to recap:
Stand up power transformer with a horizontal pan or;
Lay down transformer with a vertical pan.
Not necessarily. Reorienting the lay-down PT may solve it. Two-Rock seems to make it work.
Martin,
Hold on a second here. Raphael referenced an article (https://www.thegearpage.net/board/index ... g.1332229/) in a previous post that seems to have contribution from Two Rock personnel themselves stating that they have *not* solved the problem of electromagnetic interference with the reverb.
rootz wrote: ↑Wed Jan 15, 2020 12:44 pm
So to recap:
Stand up power transformer with a horizontal pan or;
Lay down transformer with a vertical pan.
Not necessarily. Reorienting the lay-down PT may solve it. Two-Rock seems to make it work.
Martin,
Hold on a second here. Raphael referenced an article (https://www.thegearpage.net/board/index ... g.1332229/) in a previous post that seems to have contribution from Two Rock personnel themselves stating that they have *not* solved the problem of electromagnetic interference with the reverb.
-jack
Hi Jack, thanks for the comment, I think this was relating to the early amps from 2013/2014. The more recent amps don't seem to have the same issue...so somehow they managed to sort it...
Something from their FAQ which may help? And and additional info, my reverb pan was inherited from a Custom Reverb Signature from 2017, as found on their amps
All of our amps that have reverb have a reverse phased output section. What this means is that the signal is in the negative swing as it leaves the amplifier. Traditional wiring of speakers takes the “+” positive terminal and connects it to the tip of the speaker jack, and the “-“ negative terminal and connects it to the sleeve of the speaker jack. When the speaker gets the signal in this configuration the speaker will push first and the pull. If the wiring of the cabinet is “Out of Phase” with the amp then the speaker will pull first and then push. We wire all our cabinets and combos that pair with our reverb amps with the “-“ speaker terminal going to the tip of the speaker jack and the “+” positive going to the sleeve. This way the signal that is in the negative swing as it leaves the amp see a negative polarity at the speaker. Causing it to push first and then pull. Making sure that the amplifier matches the cabinet will result in the amp/speakers working together. This will increase the dynamic range and tone of the system. It will not hurt the amp to have the speaker running in an opposite polarity then the amp. It will just sound slightly muffled and not have the headroom. Amplifiers that have no reverb will want to be wired in the traditional manner.
What if you try a shorter pan (8-type)? Will remove the pan input coil further away from the PT.
Otherwise I still believe that a high pass filter (270-470p/1M to gnd) between output of the pan and grid(stopper) of the recovery stage might help to reduce hum.
Just my 2c.
Markus
Hi Jack, thanks for the comment, I think this was relating to the early amps from 2013/2014. The more recent amps don't seem to have the same issue...so somehow they managed to sort it...
Something from their FAQ which may help? And and additional info, my reverb pan was inherited from a Custom Reverb Signature from 2017, as found on their amps
All of our amps that have reverb have a reverse phased output section. What this means is that the signal is in the negative swing as it leaves the amplifier. Traditional wiring of speakers takes the “+” positive terminal and connects it to the tip of the speaker jack, and the “-“ negative terminal and connects it to the sleeve of the speaker jack. When the speaker gets the signal in this configuration the speaker will push first and the pull. If the wiring of the cabinet is “Out of Phase” with the amp then the speaker will pull first and then push. We wire all our cabinets and combos that pair with our reverb amps with the “-“ speaker terminal going to the tip of the speaker jack and the “+” positive going to the sleeve. This way the signal that is in the negative swing as it leaves the amp see a negative polarity at the speaker. Causing it to push first and then pull. Making sure that the amplifier matches the cabinet will result in the amp/speakers working together. This will increase the dynamic range and tone of the system. It will not hurt the amp to have the speaker running in an opposite polarity then the amp. It will just sound slightly muffled and not have the headroom. Amplifiers that have no reverb will want to be wired in the traditional manner.
Interesting about the phase reversal with the reverb. I wonder if the layout/schematic should be updated to show this. i.e. the tip of the speaker jack should be negative and the ground positive.
I might try swapping this on my amp to see if it is indeed true it makes a tonal difference, I've not heard of this before...anyone?
