Anyone know how Morgan lower the hum of single coil?

[Alan0354]

I tested a Morgan Amp and the single coil strat was quieter. I had another amp to compare and it's obvious. It's not as quiet as hb, but it's close to Lace Sensors. Anyone know how they do it?

[big_teee]

Is it a head amp?
Head tube amps are usually a bit quieter with SC Pickups.
Most hum in a tube amp comes from the PT.
Maybe the PT is further from the front of the amp, or the amp uses more shielding.

[Alan0354]

Is it a head amp?
Head tube amps are usually a bit quieter with SC Pickups.
Most hum in a tube amp comes from the PT.
Maybe the PT is further from the front of the amp, or the amp uses more shielding.

It's a 50W combo with power scaling.

[tedmich]

The Morgan heads I've seen do not seem to be very "high gain" in the modern parlance, so it's much easier to give them a lower noise floor; what amp were you comparing to it? A 5150? A 3 tube preamp is almost never going to be nosier than a 5-6 tube preamp.

The gut shots I have seen seem to have std. good practice on the input lead, ie shielded input cable laid close to chassis ground plane, and he likely uses nice quiet metal film resistors (unless he's bought into the magic of CC). Better quality tubes would help too! More negative feedback can also clean up the signal...

[Chuck H]

As far as I can figure there is nothing as yet known in a guitar amp that can reduce the amount of noise the pickup is feeding into it. The amp hears anything a pickup says as signal. That's it. It's possible that the gain characteristics of the compared amps weren't comparable. On a long shot it's also possible that the Morgan amp is using some sort of noise gate? Perhaps even a frequency specific noise gate to minimize switching noise. But I'll tell you what...

Take both amps you were comparing and inject a 200mV signal into the input. Now turn the amps up until they just begin to flatten the wave form. Are the amps both making the same power? If not you need to adjust one or the other so that both amps make the same power at the point of clipping with the same input signal. When you have done this you can move to the next step...

Place the amps side by side. Place your guitar on a stand fifteen feet away. Jam a rag between the strings and the fingerboard to mute the strings. Now plug the guitar into amp A and note the amount of noise. Now plug into amp B and note the amount of noise.

They will both be the same.

There are A LOT of posts where people complain about the noise level of a particular amp only to be frustrated and blocked by the realization that they have no understanding of how to compare one amp to another WRT gain structures and noise levels.

[Chuck H]

The Morgan heads I've seen do not seem to be very "high gain" in the modern parlance, so it's much easier to give them a lower noise floor; what amp were you comparing to it? A 5150? A 3 tube preamp is almost never going to be nosier than a 5-6 tube preamp.

The gut shots I have seen seem to have std. good practice on the input lead, ie shielded input cable laid close to chassis ground plane, and he likely uses nice quiet metal film resistors (unless he's bought into the magic of CC). Better quality tubes would help too! More negative feedback can also clean up the signal, UL OT etc etc.

The rub is that he wants to know how the Morgan amps reduce the noise caused by single coil pickups. Not general amp noise.

[Alan0354]

No, I use my amp which is a standard Fender type amp, no high gain. I design noise cancellation, that's why I know about single coil noise. We are comparing clean to clean. As I explained in the other post about DC filament, I have a room that I can control the amount of hum by switching lights on and off. I can make so much noise even using low gain setting.

It is amazing the Morgan is a lot quieter. I absolutely do not believe it's the shielding practice inside the Morgan that do the job. Single coil pup is a multi turn loop antenna and I know the noise source is from my house wiring that I can control. The pup acts as an antenna. No shielding inside the amp......or matter of fact, no shielding of the guitar cavity can improve any of that.

Only way to shield the noise is to use thick ferro magnetic conductor material that is thicker than the skin depth of 60Hz. I suspect that's what Lace sensors do, they encase the coil in a thick metal tube that shield 5 out of 6 sides of the coil. The coil only receive EM signal on the top, so you can find a quiet spot much easier. But if you stand at the wrong position, Lace can hum as loud as any single coil, just because of the shielding of 5 sides. you can find a quiet spot much easier.

[Alan0354]

As far as I can figure there is nothing as yet known in a guitar amp that can reduce the amount of noise the pickup is feeding into it. The amp hears anything a pickup says as signal. That's it. It's possible that the gain characteristics of the compared amps weren't comparable. On a long shot it's also possible that the Morgan amp is using some sort of noise gate? Perhaps even a frequency specific noise gate to minimize switching noise. But I'll tell you what...

Take both amps you were comparing and inject a 200mV signal into the input. Now turn the amps up until they just begin to flatten the wave form. Are the amps both making the same power? If not you need to adjust one or the other so that both amps make the same power at the point of clipping with the same input signal. When you have done this you can move to the next step...

Place the amps side by side. Place your guitar on a stand fifteen feet away. Jam a rag between the strings and the fingerboard to mute the strings. Now plug the guitar into amp A and note the amount of noise. Now plug into amp B and note the amount of noise.

They will both be the same.

There are A LOT of posts where people complain about the noise level of a particular amp only to be frustrated and blocked by the realization that they have no understanding of how to compare one amp to another WRT gain structures and noise levels.

Too bad the amp belong to a friend of my friend that I really don't know well. They brought the amp over to test the pedals I designed. At the process, I just realize that his amp is a lot quieter. As I said, I design noise cancellation, so I know exactly how single coil pickup noise and I know the source of noise in my room is from the wiring of the house. That's the reason it's so amazing to me as I cannot see how.

I don't believe there is noise gate as Morgan is a very basic amp known for the sweet sound and touch sensitive with power scaling, this does not go in line with noise gate. In fact I don't even know how noise gate can work well as you put a threshold where you attenuate the signal that is lower than the threshold. That fundamentally changes the sound!!! I designed low level discrimination circuit that is similar, I dismissed this out right for high quality sound. Not to mention it's going to be very hard to implement with tubes.

[g1]

So aside from the pickup noise, the amps were identical tonally and volume wise?
I would think you would need to do frequency response analysis to properly compare the two amps.

[Alan0354]

Well, we set the tone to get the best guitar sound, but nobody really pay attention on the setting. I can say the guitar was played at the exactly same position. To me that is of most important as where the pickup position is very important. AND the guitar is a few feet away from the amp so I don't believe the pickup is picking up the emission of the power transformer of the the amp. Besides both amp are on at the same time all the time.

[g1]

So one amp could be boosting the frequency of the noise, while the other could be cutting that frequency.
Not paying attention to the tone settings is hardly a proper comparison. I'm sure you are aware of scientific method, we can't just ignore it when it doesn't suit our purposes.

[Alan0354]

So one amp could be boosting the frequency of the noise, while the other could be cutting that frequency.
Not paying attention to the tone settings is hardly a proper comparison. I'm sure you are aware of scientific method, we can't just ignore it when it doesn't suit our purposes.

No, particular my amp had low bass response, if anything, hum should be worst with the Morgan. As I said, I know noise cancellation and how hum is, it has 60, 120 and higher frequencies into KHz. You don't band stop certain frequency without severely impeding the sound quality. It just doesn't work that way.

[g1]

Well, you can't take out the noise from a pickup without cutting the noise frequencies. It just doesn't work that way.
If it is indeed pickup noise as you have said, then it is going in to both amplifiers. One amp is amplifying the noise more than the other amp is.

If the noise is all from the pickup, it should be very quiet when you shut off the guitar volume control. Otherwise we are talking about amp noise, not pickups.

[Alan0354]

I don't remember we shut off the guitar volume, it's not amp noise as all the amps a quiet without the guitar or with the PRS hb guitar. I have to mention, the Morgan amp is very full, rich and with big bottom compare with mine. This characteristic that will amplify the hum a lot more, but it didn't.

I know, I was and still amazed. I gave it a lot of thoughts on this, I started out thinking they shield the PT, but that won't do anything about the pickup hum. I just don't have any idea.

[Chuck H]

Take both amps you were comparing and inject a 200mV signal into the input. Now turn the amps up until they just begin to flatten the wave form. Are the amps both making the same power? If not you need to adjust one or the other so that both amps make the same power at the point of clipping with the same input signal. When you have done this you can move to the next step

Until this is done there is NO basis for comparison.