• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

HTP-1 & Buckeye Volume Issues?

ericmp1989

New Member
Joined
Feb 4, 2025
Messages
4
Likes
3
I also posted this in the HTP-1 group on AVS, but since there’s a lot of Class D amp expertise here, I figured I’d ask.

I recently bought an HTP-1 and two Buckeye Hypex NC502MP 6-channel amps. Coming from a Denon 8500, a 2x4HD, and Audyssey MultEQ-X, the learning curve has been steep. I successfully ran Dirac, followed the procedure to ensure no clipping, and (or so I thought) set the trims to 75dB. I used the "THX-like" tone in the HTP-1 for calibration and verified the levels with both the REW SPL meter and a handheld meter.

Here’s where my issue starts: The volume keeps changing. I should also note that it doesn't matter if Dirac is on or off.

Yesterday, I had everything perfectly calibrated at 75dB. This morning, I put on a demo, and something felt off. I checked with the REW SPL meter and a second handheld meter—both were now reading around 72–73dB for every channel.

To be sure, I reset the HTP-1, ran Dirac from scratch, and again landed at 72–73dB. I figured that was still plenty loud, so I set the trims accordingly and moved on.

I didn’t change a thing—my mics never left their spot. After a trip to the eye doctor, I came home, put on RP1, and suddenly, it sounded like some speaker trims were higher than others. Running the THX-like noise test again, I was now getting 76–78dB per channel.

I once again set everything back to 75dB, went to eat dinner, came back 20 minutes later, and now every channel is reading 63–68dB—without touching a thing. The main volume was still at 0dB.

What am I missing here?
 
Update:

I've had a slight ground loop since moving into this house and have tried everything to get rid of it—even hiring an electrician last year to replace every outlet and install a new breaker box. Since my subwoofer amps are in the basement while everything else is in the living room, I figured I’d just have to live with it. I should note that it got much worse when I replaced the Denon with the htp-1.

I actually asked ChatGPT and linked this thread, and it suggested checking my outlets for proper grounding. Turns out, when my first electrician installed a new outlet for my TV, he tied the ground to the neutral of the existing outlet. Once I fixed that, the hum from my subs and speakers completely disappeared!
 
Not sure what you are saying with the volume changing.

If you are playing different programme material the volume will change depending on the level in the recording. Or are you measuring the volume with a consistent test signal?
 
What are the speaker trims? (I guess a setting in the HTP-1). Are these changing. Is the volume on the HTP-1 changing?

I don't think this is an issue with the amp unless it has a fault.

I'm guessing the issue is more likely to be with HTP-1 settings, but I have no knowledge of this device, so I don't think I can help further.

The only thing I could suggest would be to reset it to factory state, and leave it there for a while without running any calibration or anything, to see if the volume still changes.
 
Turns out, when my first electrician installed a new outlet for my TV, he tied the ground to the neutral of the existing outlet. Once I fixed that, the hum from my subs and speakers completely disappeared!
Wait what. Was there a ground there that you were able to correctly wire to the outlet, or does this mean the outlet has no ground?
 
Wait what. Was there a ground there that you were able to correctly wire to the outlet, or does this mean the outlet has no ground?
In Illinois we use conduit. When the outlet is screwed into the metal box it grounds the outlet. For whatever reason my first electrician ran a physical ground wire on one outlet to the common on another outlet. I'm very happy to report that my system is silent now.

I just had something interesting happen. While watching a movie I opened Dirac, Checked something with my curve, And then went back to my movie. I changed nothing and did not upload a new file. When I closed out and went back to my movie i lost 10db across every speaker/subwoofer (measured with rew). I restarted my unit and the volume was back to normal. I was able to repeat this over and over. Is this a bug or something to get used to with Dirac?
 
In Illinois we use conduit. When the outlet is screwed into the metal box it grounds the outlet. For whatever reason my first electrician ran a physical ground wire on one outlet to the common on another outlet. I'm very happy to report that my system is silent now.
Okay so the conduit is used for ground (and presumably is grounded at the point-of-entry). Phew. In my neck of the woods, conduit is pretty much never used in residential construction (and even where it is used there's still a ground wire) so my eyebrows immediately went up.
I just had something interesting happen. While watching a movie I opened Dirac, Checked something with my curve, And then went back to my movie. I changed nothing and did not upload a new file. When I closed out and went back to my movie i lost 10db across every speaker/subwoofer (measured with rew). I restarted my unit and the volume was back to normal. I was able to repeat this over and over. Is this a bug or something to get used to with Dirac?
That definitely does not sound normal. Either something is wonky with your setup, or it's a bug. You might want to try engaging Dirac support, or perhaps @Flak could help out.
 
While watching a movie I opened Dirac,
Opening Dirac is risky. (Even if you don’t save )

The software was created to measure and calibrate systems. One of the very first steps is adjusting the speaker trims. No matter what your avr is set to, Dirac will set the master volume to something crazy low, before you get to that page. Its not a part of the save file, its a (current) master volume change.

I’ve seen this behavior on minidsp, Audiocontrol and Storm units. When l go back in to check something, it turns it down, and l just turn the volume back up afterwards.

In practice though. Before l finish a calibration l take a series of screenshots so that l don’t have to go back in.
 
Back
Top Bottom