Presence response of an HXDA

[John F]

The Presence knob on the HXDA doesn’t seem to affect the tone no matter what I set it to. I’ve swept it end to end in HX positions, and in DA positions, with various tone settings and volume and I can’t hear any difference. I’m now wondering if the amp has a fault. I’m looking for some help from HX/DA owners for their experiences. Does it seem my amp needs repair? What sound differences should I expect the Presence knob to make on the HXDA? Is there anything I should do to check it out?

Thanks in advance

 

[ViperDoc]

Could be a bad component, solder joint or ground. You’d have to pull the chassis, drain the power supply capacitors properly so you don’t get electrocuted and then test the presence circuit. Call your local amp tech.

 

[RickP]

Keep in mind that a Presence control is much less apparent than the treble pot, and affects a narrower, higher section of the guitar range. I’ll check mine tomorrow and see how apparent it is at extreme settings. As I recall, mine is normally in the 10-2 o’clock area of the dial, depending on guitar or cab used.

 

[DISTORT6]

Try turning the treble completely off and then turn the presence up and down.
That should tell you if it’s actually functioning or not.

 

[RickP]

Just spent some time playing one of my HX/DAs, and the Presence control functions as expected. Again, it is targeted at the upper treble range, so that’s where you hear it. And like any high end signal, it’s less apparent the more the amp is overdriven. I keep mine in a place where it has a nice rock grind but cleans up with the guitar’s volume rolled back, and the effect of the Presence control is noticeable but acceptable across its entire range of settings.

If you hear no effect at all, something is wrong. If the difference in the upper frequencies (the sparkly highs, some call them) is there, but is not pronounced unless going from 1-10 on the control, I dare say it’s working as intended.

 

[John F]

Thanks Rick. I’ll check mine again.

 

[László]

The presence control on mine works as expected, as Rick says.

 

[John F]

Thank you Les. Not sure my problem is the amp or my hearing aids. Could be both. More testing required.

 

[Deleted member 5962]

Thank you Les. Not sure my problem is the amp or my hearing aids. Could be both. More testing required.

I’m not sure if you’re joking or not about hearing aids… if you are not, record a quick clip even if it’s with your phone. We should be able to hear if it’s working or not even with a phone recording.

 

[John F]

Yes, I’m serious about wearing hearing aids.

I just worked the amp over for about an hour with the gain low and master volume high to get a clean tone. I can hear all the notes up the neck just fine. I tried all combinations of the 3 tone knobs while turning presence from full ccw to full cw and I can’t hear anything more than a slight difference in sound from the presence knob. My Marshall 5 watt and my PRS Custom 20 both have presence knobs and I can plainly hear even small changes in the setting. I really think the amp has a fault. Anyone have a schematic?

 

[László]

Unfortunately, PRS didn't publish a schematic that I'm aware of.

Were you able to reach them by phone? They might be able to walk you through troubleshooting it.

 

[John F]

I didn’t try to contact the company. I’m in a holding pattern at the moment, enjoying the amp anyway. Thanks for the follow-up.