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Re: VP150
hawk1061 #359708 11/29/11 07:35 PM
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Originally Posted By: hawk1061
FYI, replacement drivers are $46USD each, so at this point in time I believe that I will take the two step approach:

1) Replace the 3 drivers in the VP150
2) Use the feature on the HK 7200 which limits the volume.

Only question is, how do I know what to set the upper limit at? Is there some physical way to know just by listening? Or would I need an oscope?

BTW, I did not have the receiver set to "Loud", it was on "Soft"


Having the volume limit set on the receiver is always a good idea no matter what. This will prevent your speakers from any damage in the future from your wife or guests, but the reason why your wife turned up the volume so loud was to get sound across the house and even OUTSIDE mind you. That is the big problem you have to solve. This is an unreasonable and ridiculous application to begin with and now adding a volume limiter to get reasonable volumes of music through multiple rooms and outside from a distant room won't work very well IMO.




I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne
Re: VP150
BlueJays1 #359711 11/29/11 08:15 PM
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I can recall once when I did not have the volume limit set and my remote control went batshit and pegged the volume on my 7200. My ears rang for quite a spell after I changed my shorts.

No Tom, and no Chess.... None of my failed receivers ever caught fire....smartasses. smile They just decided to not work. I did however have a stinking .50 cent fuse blow on the 7200. Cost me $100 service charge to fix..

Re: VP150
michael_d #359715 11/29/11 09:40 PM
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BlueJays1,

I agree with you, it's not reasonable. However, stuff like this does happen from time to time (not with regularity or it probably would have destroyed the drivers earlier).

Besides, I purchased the system and gave it to her for her birthday, so technically it's her's to do with as she wishes.

However, after I explained last night that blasting the volume so she could hear outside the house is what most likely caused the failure, she does understand. To be certain it does not recurr, I will activate the volume limiter

The volume scale on the HK 7200 goes from maybe -60 (lowest) up to maybe +5 (highest) in the display, not sure why it starts at a negative number. Typically I would set it at -15 for great audio movies like Master and Commander or Star Trek, hopefully that keeps it out of the clipping range.

Is there a way to test it? Would I need to hook up an oscope to view the waveform coming out in order to determine the exact clipping point? Also, will clipping vary with ambient room temperature and the temperature of the equipment (hotter making clipping occur lower on the volume scale)?

Re: VP150
hawk1061 #359717 11/29/11 10:22 PM
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you could very well check it on a scope, it will always show you clipping even if it's happening by only a small amount.

i don't know what other piece of equipment (that gives good results) you could get for that.

others will tell you more. :-)

Re: VP150
J. B. #359719 11/29/11 10:55 PM
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There really isn't another piece of test equipment that will tell you if you are driving the amp to hard. Yes clipping will vary with the ambient temperature, like i said earlier, the whole point is to keep the transistors cool.. search the online pdf version of your receiver, there may be a "clipping" indicator. On the amp i have in the bedroom, each channel has a clipping LED indicator, that will light up if a channel is being driven into the clipping region, i don't know if this is an option that receivers have or not.

When i would tell you to set the max volume maybe 5-10% higher than your "reference" level, which for you would be your movie level. See how everything works at the max setting, and go from there, But keep in mind, if your wife has another party, and one of her friends does turn it up, they may reach the max setting, and the system may be left there for an extended period of time, so keep this in mind.

Unfortunately, this is one of those topics that is a grey area, there is no quantitative answer that we can provide you. One option would be to call the manufacture, and talk to a technician, they will have MUCH more information on what a safe level for extended use would be.

Re: VP150
hawk1061 #359728 11/30/11 03:28 AM
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Steve, small amounts of clipping are harmless and generally inaudible. Yes, other than hearing the distorted sound if it was heavy and prolonged, examining the waveform on an oscilloscope is the way to detect flattening of the wave tops.

As a practical matter, as Mike pointed out above, you're not going to have significant clipping taking place with an amplifier as powerful as the one in the 7200 if the sound level isn't dangerously high. Again, using an SPL meter, such as the digital model from RadioShack, is a good way to monitor actual sound levels which are experienced at the listening position.


-----------------------------------

Enjoy the music, not the equipment.


Re: VP150
JohnK #359729 11/30/11 03:45 AM
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Hawk also if you are a user of either iPad or iPhone there is a free SPL app that will be sufficient for monitoring the pressure levels your system is putting out, for calibration purposes I'd recommend the Radio Shack meter but for monitoring loudness levels the i apps will be perfectly fine.


Rick
Our Room

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Re: VP150
hawk1061 #359746 11/30/11 11:14 AM
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Hawk, your H/K volume indicatorn (like my H/K and many other receivers) is calibrated in decibels (dB). For your purposes, you can assume that "0 dB" on the H/K readout is at or approaching the maximum output of the amplifier, so avoida that level and keep your playback levels to a max of -10 dB. My H/K's settings are very similar to yours. Loud movie playback is a -15 db. Music in DD 5.1 or DPLII is around =20 to -25 dB. The latter will vary depending on how "hot" the CD or source recorded level is, which also affects clipping.

There are no accessory clipping indicators, and the complexity of the music will also affect clipping, so it's impossible to determine an exact clipping point. Just stay away from the 0 dB point on the H/K and you'll be fine.

Regards,
Alan


Alan Lofft,
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Re: VP150
alan #359747 11/30/11 11:26 AM
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There is some info about accessory peak reading meters here:
http://forum.qscaudio.com/forum/viewtopi...24931420dd51d3c

Too costly for my use, i did not buy one; but the info could be useful for others.

Re: VP150
hawk1061 #359748 11/30/11 11:53 AM
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Hawk, if you want to understand the decibel, here's a link to an article of mine in the Axiom articles archive:

http://www.axiomaudio.com/understandingdb.html

Just remember, as the negative numbers get smaller, the power output of your H/K amplifier increases--gets louder. Over 0 dB, the number turn positive and puts you in the region of distortion and clipping. The relationship of dB and loudness levels on the H/K is accurate, so if you increase your volume level from -23 dB to -20 dB, an increase of 3 dB, the music will get "somewhat louder", but will require the H/K amp to produce twice as much power in watts for that slight increase in listening volume. To make music subjectively "twice as loud" will require ten times as much power from the amp.

Alan


Alan Lofft,
Axiom Resident Expert (Retired)
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