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A/C vs Amp?

1598 Views 34 Replies 13 Participants Last post by dsmith901, Mar 1, 2005

Halfrican

Discussion Starter · Feb 28, 2005

Hello all,

I am the up until recently happy owner of an Integra DTA-9.4 Multi Channel Amplifier. I purchased this unit new from a local B&M store along with the matching pre-amp (DTC-9.4).

According to Integra, the amp was built from the ground up to meet the demands of todays current hungry speakers. I used the unit for one year with a set of 8 ohm Polk Audio Speakers without incident, unit performed flawlesly with seemingly unlimited power reserves.

Recently (Oct 04) moved to a new construction home, and suddenly the problems started to appear. My new environment appears to have changed the perfomance of my amp for the worse. I now find that even though I am in a CONSIDERABLY smaller room than before, I am no longer able to playback most soundtracks at anywhere near reference level. At levels above -20db THX levels I am experiencing what I would describe as clipping (never head this amp clip before, so I can only assume that is the sound I am hearing). The distortion only occurs during soundtrack peaks, and often when there are large quantities of bass.

The reason I am speculating that the issue I am having may have to do with the A/C of the new house is that the line voltage appears to be on the low side (around 115 to 110 depeding on time of day). My previous residence had a steady 120 available all day long. Could this lack of voltage be causing issues with the amp?

I already had the borough electric company verify that my wiring was good to the house and that it passed a load test.

I had two dedicated 20 amp circuits installed in the HT room

I have also done exhaustive trial and error on routing of cables

Recently purchased new speakers, issue still exists.

Considering trying a different amplifier, but I am likely to take a drastic loss, and am doubtful that it will resolve the issue since the Integra did so well in the previous home.

Would a product like the Monster Cable AVS2000 (voltage stabilizer) likely help my issue? Is there something else I should be asking of my Electric Company or Electric Contractor?

Sorry to be so long winded, but I have been trying to resolve this issue since Oct 2004, and am running out of ideas...

Thanks,

Mark

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1 - 20 of 35 Posts

DonoMan

· #2 · Feb 28, 2005

A few suggestions:

1) If you have a multimeter, measure your mains voltage for a few minutes and see if the value varies by more than a couple volts...

2) See if you can arrange an in-home trial for a power conditioner. I doubt it will help, though. Use as a last resort.

3) Consider that something may have gotten damaged during the move(unlikely), or some setting or wire got moved.

RCbridge

· #3 · Feb 28, 2005

You mentioned you are now in a smaller room, are you sure nothing in it is vibrating during those peaks?

Does it sound like the distortion is everywhere or can you pinpoint it?

(Trying to rule out a damaged speaker, loose grilll).

Do you own a DVM if so when you experience those distortions connect the DVM (and cover your ears) as close to the amp outlet as possible and look for a voltage drop (if the meter will react that quickly).

Last if all else fails turn it down a notch!!

Kevin. W

· #4 · Feb 28, 2005

Quote:

Originally posted by Halfrican
Hello all,

I am the up until recently happy owner of an Integra DTA-9.4 Multi Channel Amplifier. I purchased this unit new from a local B&M store along with the matching pre-amp (DTC-9.4).

According to Integra, the amp was built from the ground up to meet the demands of todays current hungry speakers. I used the unit for one year with a set of 8 ohm Polk Audio Speakers without incident, unit performed flawlesly with seemingly unlimited power reserves.

Recently (Oct 04) moved to a new construction home, and suddenly the problems started to appear. My new environment appears to have changed the perfomance of my amp for the worse. I now find that even though I am in a CONSIDERABLY smaller room than before, I am no longer able to playback most soundtracks at anywhere near reference level. At levels above -20db THX levels I am experiencing what I would describe as clipping (never head this amp clip before, so I can only assume that is the sound I am hearing). The distortion only occurs during soundtrack peaks, and often when there are large quantities of bass.

The reason I am speculating that the issue I am having may have to do with the A/C of the new house is that the line voltage appears to be on the low side (around 115 to 110 depeding on time of day). My previous residence had a steady 120 available all day long. Could this lack of voltage be causing issues with the amp?

I already had the borough electric company verify that my wiring was good to the house and that it passed a load test.

I had two dedicated 20 amp circuits installed in the HT room

I have also done exhaustive trial and error on routing of cables

Recently purchased new speakers, issue still exists.

Considering trying a different amplifier, but I am likely to take a drastic loss, and am doubtful that it will resolve the issue since the Integra did so well in the previous home.

Would a product like the Monster Cable AVS2000 (voltage stabilizer) likely help my issue? Is there something else I should be asking of my Electric Company or Electric Contractor?

Sorry to be so long winded, but I have been trying to resolve this issue since Oct 2004, and am running out of ideas...

Thanks,

Mark

I have a feeling that its the room and not the equipment. I'd look first at taming the room acoustics before moving onto voltage regulation. How different are size and shape of the room? What about items in the room.

Kevin

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DMF

· #5 · Feb 28, 2005

I agree with Kevin. I don't think the line voltage has anything to do with it.

I bet you don't have an SPL meter.

blazar

· #6 · Feb 28, 2005

I'f there is a HUGE difference it's likely not simply a broken room either. I still vote for damage to the amp itself as a possiblity. Do you have in a setting where it is drastically overheating or anything?

Halfrican

Discussion Starter · #7 · Feb 28, 2005

Thanks for all your replys,

I do have both a Digital Voltage meter, and a SPL Meter (DMF), this system has a total value in excess of $25,000 I have definitely taken the time to make sure that the setup was done properly, I am an extremely detail oriented person (a.k.a. anal retentive).

The system has been calibrated using both the internal test tones of the pre-amp as wells as Avia Guide to Home Theater.

I seriously doubt that I am experiencing some kind of room noise, as the room is dedicated to just the home theater equipment, and I have literally nothing but the equipment, couch, and dvd racks in the room.

The speakers that I am currently using were purchased new about one month ago, they are in perfect working order as far as I can tell. The noise existed prior to the purchase of these speakers as mentioned in my original post.

As far as damage to my equipment in the move is concerned, I personally packed the equipment in the original boxes and transported it in my personal vehicle (my spouse thought I was nuts) so the movers never got their hands on them. Amp is definitely not over heating, I have tried using the equipment with and without a A/C power conditioner, just not the Voltage Stabilizer.

I will double check any possible room vibration issues, but the sound that I'm hearing is more like a "crackle" during the peaks, again usually when there is also a substanial bass peak also. I am hard pressed to figure out what items in the room resonating, might make this kind of noise.

Thanks again for all your input...

half

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Halfrican

Discussion Starter · #8 · Feb 28, 2005

Quote:

Originally posted by DonoMan
A few suggestions:

1) If you have a multimeter, measure your mains voltage for a few minutes and see if the value varies by more than a couple volts...

2) See if you can arrange an in-home trial for a power conditioner. I doubt it will help, though. Use as a last resort.

3) Consider that something may have gotten damaged during the move(unlikely), or some setting or wire got moved.

Donoman,

Yes I have a multimeter, but I am not an expert on A/C. When you say measure the voltage of the mains, where would I do this? Sorry if that sound liek a dumb question.

I will contact the dealer where I purchased equipment to discuss an in-home trial of the Voltage Stabilizer, however they charge a serious premium (over retail) for the unit and I likely won't purchase it from them. Most of the equipment they price at M.S.R.P. but this item is several hundred over for some reason. I could purchase from Crutchfiled since they have a 30 day trial and free shipping both ways.

Half

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DonoMan

· #9 · Feb 28, 2005

Plug the red lead into the short pole and the black into the tall poll. Make sure your meter is set for the 200VAC scale.

Halfrican

Discussion Starter · #10 · Feb 28, 2005

Quote:

Originally posted by DonoMan
Plug the red lead into the short pole and the black into the tall poll. Make sure your meter is set for the 200VAC scale.

Sorry for the dumb question, unit is now reading between 119.8 and 118.9 but I am not running the system hard. It's still morning here, my spouse will kick my butt if I wake her up with the opening seen of Episode II (hehehe).

I will keep an eye on the DMM to see what happens over a days time, then let you know. The problem seems to manifest itself more in the evening, however, it may just an issue of when I get to listen to my system.

Thanks again DonoMan....

Half

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Kevin. W

· #11 · Feb 28, 2005

Quote:

Originally posted by Halfrican
Thanks for all your replys,

I seriously doubt that I am experiencing some kind of room noise, as the room is dedicated to just the home theater equipment, and I have literally nothing but the equipment, couch, and dvd racks in the room.

How does this compare to the room it is was in previously. Did you have any other stuff in the old room that could have been obsorbing the sound. What was the shape of the old room compared to the new?

Quote:

As far as damage to my equipment in the move is concerned, I personally packed the equipment in the original boxes and transported it in my personal vehicle (my spouse thought I was nuts) so the movers never got their hands on them.

Your not the only one. Did the same thing the last time I moved.

Quote:

I will double check any possible room vibration issues, but the sound that I'm hearing is more like a "crackle" during the peaks, again usually when there is also a substanial bass peak also. I am hard pressed to figure out what items in the room resonating, might make this kind of noise.

Try inroducing some more sound damping items to room and see if it works

Kevin

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Halfrican

Discussion Starter · #12 · Feb 28, 2005

Quote:

Originally posted by Kevin. W
How does this compare to the room it is was in previously. Did you have any other stuff in the old room that could have been obsorbing the sound. What was the shape of the old room compared to the new?

Your not the only one. Did the same thing the last time I moved.

Try inroducing some more sound damping items to room and see if it works

Kevin

Old room was a semi-rectangular "great room" with openings hallways to other levels of the house, and lots of windows (not ideal). New room is a "bonus room" over garage. 13' wide x 21' long, tapered ceiling, about 9' tall at the peak. Room has door seperating it from other rooms of house.

Thanks for your input

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Dave W

· #13 · Feb 28, 2005

Quote:

As far as damage to my equipment in the move is concerned, I personally packed the equipment in the original boxes and transported it in my personal vehicle (my spouse thought I was nuts) so the movers never got their hands on them.

I've done the same thing each time I've moved.

As far as the distortion you're hearing, like the others here, I'm wondering about room vibration. I've always been amazed at how much something vibrating in the room can sound like bad distortion. Once I thought for sure my sub was broken, then I looked behind it and saw a magazine had fallen behind the sub against the wall. Whenever a strong bass passage came on, that paper buzzed and rattled like a broken driver cone. It was amazing how loud it was. Some THX DVDs have bass ramp test on them which is excellent for check room vibration. It starts above 100 Hz and slowly ramps down to 20 Hz. If something in the room is resonating at a particular frequency, this test will show it. You can also try the individual bass test tones available on some discs, like the Stereophile test CDs. Play each tone at high volume, and listen for room vibration.

Dave

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Halfrican

Discussion Starter · #14 · Feb 28, 2005

Quote:

Originally posted by Dave W
I've done the same thing each time I've moved.

As far as the distortion you're hearing, like the others here, I'm wondering about room vibration. I've always been amazed at how much something vibrating in the room can sound like bad distortion. Once I thought for sure my sub was broken, then I looked behind it and saw a magazine had fallen behind the sub against the wall. Whenever a strong bass passage came on, that paper buzzed and rattled like a broken driver cone. It was amazing how loud it was. Some THX DVDs have bass ramp test on them which is excellent for check room vibration. It starts above 100 Hz and slowly ramps down to 20 Hz. If something in the room is resonating at a particular frequency, this test will show it. You can also try the individual bass test tones available on some discs, like the Stereophile test CDs. Play each tone at high volume, and listen for room vibration.

Dave

Point taken, I once was sure something was distorting when actually it was a picture banging against a wall like a piece of paper fluttering in the wind! Unfortunately, the new room has nothing hanging on the wall except the surround side/surround back speakers.

half

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DMF

· #15 · Feb 28, 2005

Try feeding discrete tones to the sub, or use one of the really slow bass sweeps on the disk (I think they (Avia and DVE) both have one). Turn that sucker up loud. You will hear any rattling or excitation pretty clearly as you hit the resonant frequency.

However, the suggestions about the room were not based on noise, but on nulls. You could indeed be clipping because you have the gain (or the EQ) way up trying to overpower a room null. A null is like a black hole. It will eat any amp in existence.

blazar

· #16 · Feb 28, 2005

are the crackles dependent on the volume you run the amp at?

try the amp in a different room or in a different building altogether. Or run a power cord out into another room and see if there is a difference.

Lastly, I guess you are sure this is not a pre-amp or source problem of some kind?

Halfrican

Discussion Starter · #17 · Feb 28, 2005

Quote:

Originally posted by DMF
Try feeding discrete tones to the sub, or use one of the really slow bass sweeps on the disk (I think they (Avia and DVE) both have one). Turn that sucker up loud. You will hear any rattling or excitation pretty clearly as you hit the resonant frequency.

However, the suggestions about the room were not based on noise, but on nulls. You could indeed be clipping because you have the gain (or the EQ) way up trying to overpower a room null. A null is like a black hole. It will eat any amp in existence.

No EQ's in system, and the gain's on the pre-amp are all at less than "0" no boost at all.

Still going to work on the "room" issues to see if there is something that I can pinpoint.

half

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DanFrancis

· #18 · Feb 28, 2005

Where are the seats located?

With dimensions of 13x21 your first axial modes for length and width will be at 6.5' from the side walls and 10.5-11.5' from the front wall. You'll also experience nulls at 1/4, 3/4 room length and width (for different bass frequencies). Here's the deal; your last room was basically the entire house (acoustically anyway)- that would qualify as a large room, your new room qualifies as a small-room acoustically. Small room acoustics are more difficult to optimize because you can move one step (roughly 2.5 feet) in any direction and the sound changes drastically. what you might want to try (for gits and shiggles) is move the SPL meter one step in any direction from the "sweet spot" and go through setting your levels and distances again, you may want to make sure that everything is in phase as well (not just through the wiring either). See if just moving the step makes a difference for you and your rattle, indeed it sounds like you're pushing the sub too hard- so try that and see what happens, since the symptoms point to you sitting in a null.

Dan

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Kevin. W

· #19 · Mar 1, 2005

Quote:

Originally posted by Halfrican
Sorry for the dumb question, unit is now reading between 119.8 and 118.9 but I am not running the system hard. It's still morning here, my spouse will kick my butt if I wake her up with the opening seen of Episode II (hehehe).

I will keep an eye on the DMM to see what happens over a days time, then let you know. The problem seems to manifest itself more in the evening, however, it may just an issue of when I get to listen to my system.

Thanks again DonoMan....

Half

Have you taken a reading this evening to see what it is? I just figured out how to use my multimeter. This afternoon it read 114-115v and this evening I'm getting 110v.

Kevin

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DonoMan

· #20 · Mar 1, 2005

I'd say anywhere from 110 to 120 is fine... It's okay if it varies like that over hours or longer, though if it was constantly going between 110 and 120, then I'd get an online UPS (a UPS where the load is always connected through the UPS circuitry... I recommend Liebert brand for this) as you can find them cheaper than a power conditioner and they're better.

120 is better than 110, though.

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