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#1
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Bose 901 EQ distortion
Hello all,
First, I like my 901s regardless so no flaming please. I need help with this condition: I have two sets of 901's. One pair of series IV and one pair of series VI, both with the matching Bose EQ. My problem is that some CD,s and even some passages on soother CD's cause distortion when using the EQ. This can be at any volume level. I have only had this problem with recent CDs. (Diana Krawl, Chris Botti) All my older CD's and the radio plays fine and loud. I have tried different recievers, CD decks and even replaced all the caps in one of the EQs. Anyone else having issues or know where I can find a service manual for these EQ's? Really appreciate the help |
#2
Posted to rec.audio.tech
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Bose 901 EQ distortion
wrote in message ... Hello all, First, I like my 901s regardless so no flaming please. I need help with this condition: I have two sets of 901's. One pair of series IV and one pair of series VI, both with the matching Bose EQ. My problem is that some CD,s and even some passages on soother CD's cause distortion when using the EQ. This can be at any volume level. I have only had this problem with recent CDs. (Diana Krawl, Chris Botti) All my older CD's and the radio plays fine and loud. I have tried different recievers, CD decks and even replaced all the caps in one of the EQs. Anyone else having issues or know where I can find a service manual for these EQ's? Really appreciate the help Many recent vintage CD's are mastered LOUD and compressed. May be a maxxed out, clipped signal being fed to the EQ, or the EQ may be running out of headroom, again because of the nature of the signal itself. One would need to look at the signal with an oscilloscope at the input of the EQ, at various points inside (at the output pins of the various op-amps inside for example) and at the output of the EQ itself. If the signal is reaching the box that way, you may need a different source unit since the clipping may be occurring there or for that matter might be coming out of your CD player that way. Mark Z. |
#3
Posted to rec.audio.tech
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Bose 901 EQ distortion
On Tue, 4 Dec 2007 18:06:04 -0800 (PST), wrote:
Hello all, First, I like my 901s regardless so no flaming please. I need help with this condition: I'm sorry, but if you are going to leave a hat lying on the road, I'm gonna kick it. I agree wholeheartedly with your statement above. d -- Pearce Consulting http://www.pearce.uk.com |
#4
Posted to rec.audio.tech
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Bose 901 EQ distortion
"Mark D. Zacharias" wrote in message
. net... wrote in message ... Hello all, First, I like my 901s regardless so no flaming please. I need help with this condition: I have two sets of 901's. One pair of series IV and one pair of series VI, both with the matching Bose EQ. My problem is that some CD,s and even some passages on soother CD's cause distortion when using the EQ. This can be at any volume level. I have only had this problem with recent CDs. (Diana Krawl, Chris Botti) All my older CD's and the radio plays fine and loud. I have tried different recievers, CD decks and even replaced all the caps in one of the EQs. Anyone else having issues or know where I can find a service manual for these EQ's? Really appreciate the help Many recent vintage CD's are mastered LOUD and compressed. May be a maxxed out, clipped signal being fed to the EQ, or the EQ may be running out of headroom, again because of the nature of the signal itself. One would need to look at the signal with an oscilloscope at the input of the EQ, at various points inside (at the output pins of the various op-amps inside for example) and at the output of the EQ itself. If the signal is reaching the box that way, you may need a different source unit since the clipping may be occurring there or for that matter might be coming out of your CD player that way. Mark Z. Indeed. I have known some early CD players that would clip by 0dBFS. This wasn't that much of an issue in the early days of CD when mastering actually left some headroom, but with recent CDs which hit 0dBFS pretty frequently, this could be what you're hearing. I have checked one or two of my Diana Krall CDs and they *are* taken to 0dBFS frequently. Recent CD players shouldn't do this, but then again, they might. S. -- http://audiopages.googlepages.com |
#6
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Bose 901 EQ distortion
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#7
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Bose 901 EQ distortion
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#8
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Bose 901 EQ distortion
On Dec 5, 2:22 pm, Chris Morriss wrote:
In message , writes Hello all, First, I like my 901s regardless so no flaming please. I need help with this condition: I have two sets of 901's. One pair of series IV and one pair of series VI, both with the matching Bose EQ. My problem is that some CD,s and even some passages on soother CD's cause distortion when using the EQ. This can be at any volume level. I have only had this problem with recent CDs. (Diana Krall, Chris Botti) All my older CD's and the radio plays fine and loud. I have tried different recievers, CD decks and even replaced all the caps in one of the EQs. Anyone else having issues or know where I can find a service manual for these EQ's? Really appreciate the help Perhaps the high output signal is overloading the input on the equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors in an 'L' network for each channel)? This may drop the signal enough. What is the input spec for the equaliser? Modern highly-compressed CDs may be putting out 2V rms or so and that may be the problem. -- Chris Morriss Thanks for the help folks. Yes the problem seems to be on both channels and I have tryed it on two different systems. I was thinking to try attenuation as well. I have tried different CD players and even drove the eq's input off of a portable cd deck headphone jack with varied volume output and could detect the distortion at very low levels. Does the RMS voltage value remain constant on a headphone channel? I don't know the input spec on the bose Eq but would apprecieate it anyone has that information or a link to a service manual. I can't belive that I am the only person haveing these issues or that I have aquired two systems with the same problem. A call to Bose says they will check out the EQ for 60 dollars. I assume new systems they are selling have upgraded EQs. What are they doing or changing? Love the "hat" comment. I deserve it. Thanks again, Any other comments? |
#9
Posted to rec.audio.tech
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Bose 901 EQ distortion
wrote in message
On Dec 5, 2:22 pm, Chris Morriss wrote: In message , writes Hello all, First, I like my 901s regardless so no flaming please. I need help with this condition: I have two sets of 901's. One pair of series IV and one pair of series VI, both with the matching Bose EQ. My problem is that some CD,s and even some passages on soother CD's cause distortion when using the EQ. This can be at any volume level. I have only had this problem with recent CDs. (Diana Krall, Chris Botti) All my older CD's and the radio plays fine and loud. I have tried different recievers, CD decks and even replaced all the caps in one of the EQs. Anyone else having issues or know where I can find a service manual for these EQ's? Really appreciate the help Perhaps the high output signal is overloading the input on the equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors in an 'L' network for each channel)? This may drop the signal enough. What is the input spec for the equaliser? Modern highly-compressed CDs may be putting out 2V rms or so and that may be the problem. -- Chris Morriss Thanks for the help folks. Yes the problem seems to be on both channels and I have tryed it on two different systems. I was thinking to try attenuation as well. I have tried different CD players and even drove the eq's input off of a portable cd deck headphone jack with varied volume output and could detect the distortion at very low levels. Distortion at low levels could be due to corroded contacts. Does the RMS voltage value remain constant on a headphone channel? No. The sound level in your earphones changes, right? I don't know the input spec on the bose Eq but would apprecieate it anyone has that information or a link to a service manual. It is probable that your equipment isn't meeting spec. IOW, it has failed to operate properly. I can't belive that I am the only person haveing these issues or that I have aquired two systems with the same problem. Both samples could be failing the same if it is due to something like electrolytic caps failing, or problems with a common power supply... A call to Bose says they will check out the EQ for 60 dollars. Typical. I assume new systems they are selling have upgraded EQs. What are they doing or changing? The eqs are designed to match the speakers, and newer models of the speakers no doubt need different eq. There will also be some changes due parts from the old eqs no longer being available. |
#11
Posted to rec.audio.tech
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Bose 901 EQ distortion
On Dec 6, 12:24 pm, (GregS) wrote:
In article , wrote: On Dec 5, 2:22 pm, Chris Morriss wrote: In message , writes Hello all, First, I like my 901s regardless so no flaming please. I need help with this condition: I have two sets of 901's. One pair of series IV and one pair of series VI, both with the matching Bose EQ. My problem is that some CD,s and even some passages on soother CD's cause distortion when using the EQ. This can be at any volume level. I have only had this problem with recent CDs. (Diana Krall, Chris Botti) All my older CD's and the radio plays fine and loud. I have tried different recievers, CD decks and even replaced all the caps in one of the EQs. Anyone else having issues or know where I can find a service manual for these EQ's? Really appreciate the help Perhaps the high output signal is overloading the input on the equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors in an 'L' network for each channel)? This may drop the signal enough. What is the input spec for the equaliser? Modern highly-compressed CDs may be putting out 2V rms or so and that may be the problem. -- Chris Morriss Thanks for the help folks. Yes the problem seems to be on both channels and I have tryed it on two different systems. I was thinking to try attenuation as well. I have tried different CD players and even drove the eq's input off of a portable cd deck headphone jack with varied volume output and could detect the distortion at very low levels. Does the RMS voltage value remain constant on a headphone channel? I don't know the input spec on the bose Eq but would apprecieate it anyone has that information or a link to a service manual. I can't belive that I am the only person haveing these issues or that I have aquired two systems with the same problem. A call to Bose says they will check out the EQ for 60 dollars. I assume new systems they are selling have upgraded EQs. What are they doing or changing? Love the "hat" comment. I deserve it. Thanks again, Any other comments? I would check the supply on the opamp pins. You need a diagram of the specific chip. The should be at least 15 volts minimum between plus and minus up to about 30 volts which is normally used. If you have a scope look for ripple. If I recall the series 3 EQ I replaced the caps in it had opamps, don't remember which chip. I will check the voltage available on the plus pins I have seen a couple of models of the equalizer. Some seem outlandish in their opperation. One, I could not reduce the treble enough. The orginal model came out and the second model, a fully transistorized unit had a little more selection than the first. After that they were chip opamps, typically using TLO74's or TLO72's, can't remember. The first models escentially mimicked the orginal, with even more boost selection, some uncontrolable. After that, it seemed they were less concerned with the boost, but added a type of midrange control. If you suck out the low mids, it would appear to do the same thing as boost the treble and bass. Bose always says they make improvements, like over a hundred improvements, more like 100 cost saving features. greg- Hide quoted text - - Show quoted text - Still looking. Anyone else have this experience? Bose is playing ignorant "never heard of anything like that before". Two totally different systems with the same problem. Thanks for the help. |
#12
Posted to rec.audio.tech
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Bose 901 EQ distortion
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#13
Posted to rec.audio.tech
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Bose 901 EQ distortion
wrote in message
Still looking. Anyone else have this experience? Bose is playing ignorant "never heard of anything like that before". Maybe the person you're talking to is a new hire. Two totally different systems with the same problem. Here's a radical solution - get two channels of parametric equalizer and dial in the frequency response of your dreams. |
#14
Posted to rec.audio.tech
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Bose 901 EQ distortion
On Dec 6, 7:54 pm, "Arny Krueger" wrote:
wrote in message Still looking. Anyone else have this experience? Bose is playing ignorant "never heard of anything like that before". Maybe the person you're talking to is a new hire. Two totally different systems with the same problem. Here's a radical solution - get two channels of parametric equalizer and dial in the frequency response of your dreams. Called Bose agan. Got a different guy who said to send the eq back and they will have a look gratis. (Still says they have never heard of anything like this. The price is right so it's going back. Thanks to all |
#15
Posted to rec.audio.tech
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Bose 901 EQ distortion
Arny Krueger wrote:
Here's a radical solution - get two channels of parametric equalizer and dial in the frequency response of your dreams. Wasn't it the DEQ 2496 that was mentioned in a similar context in a nearby newsgroup? Kind regards Peter Larsen |
#16
Posted to rec.audio.tech
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Bose 901 EQ distortion
"Peter Larsen" wrote in message
Arny Krueger wrote: Here's a radical solution - get two channels of parametric equalizer and dial in the frequency response of your dreams. Wasn't it the DEQ 2496 that was mentioned in a similar context in a nearby newsgroup? Could be. I've never had one to play with, but lots of people seem to like 'em. A digital parametric like the DEQ is a better choice for eq newbies if it has a real-time frequency response display. Helps people match up what they are doing with what they are hearing. |
#17
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Bose 901 EQ distortion
"Arny Krueger" wrote ...
"Peter Larsen" wrote Arny Krueger wrote: Here's a radical solution - get two channels of parametric equalizer and dial in the frequency response of your dreams. Wasn't it the DEQ 2496 that was mentioned in a similar context in a nearby newsgroup? Could be. I've never had one to play with, but lots of people seem to like 'em. A digital parametric like the DEQ is a better choice for eq newbies if it has a real-time frequency response display. Helps people match up what they are doing with what they are hearing. Is the curve of the Bose EQ box published anywhere? |
#18
Posted to rec.audio.tech
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Bose 901 EQ distortion
In article , "Richard Crowley" wrote:
"Arny Krueger" wrote ... "Peter Larsen" wrote Arny Krueger wrote: Here's a radical solution - get two channels of parametric equalizer and dial in the frequency response of your dreams. Wasn't it the DEQ 2496 that was mentioned in a similar context in a nearby newsgroup? Could be. I've never had one to play with, but lots of people seem to like 'em. A digital parametric like the DEQ is a better choice for eq newbies if it has a real-time frequency response display. Helps people match up what they are doing with what they are hearing. Is the curve of the Bose EQ box published anywhere? I think I saw it on the patent. Anyway, its flat from 100 to about 2 kHz. There is up to an 18 dB peak at 30 Hz, and a 12 dB peak at 12 kHz. Essentially, most everything is lost above 12 kHz. greg |
#19
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Bose 901 EQ distortion
"GregS" wrote...
"Richard Crowley" wrote: Is the curve of the Bose EQ box published anywhere? I think I saw it on the patent. Anyway, its flat from 100 to about 2 kHz. There is up to an 18 dB peak at 30 Hz, and a 12 dB peak at 12 kHz. Essentially, most everything is lost above 12 kHz. That would make a bullhorn or a telephone sound good! :-) |
#20
Posted to rec.audio.tech
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Bose 901 EQ distortion
Richard Crowley wrote:
Is the curve of the Bose EQ box published anywhere? It looks like the image of a gletcher valley cross-section ... Someone over in a.a.p.l-s linked to an image of an analysis of it, i have it somewhere on some harddisk, mostly I think it was about the 802's ... but in case of the deq one just needs a measuring microphone and to aim for the b&k living room reference curve, the simplified version is flat up to 200 Hz and then drops smoothly to -6 dB at 20 kHz, aiming for perfection at the extremes is folly. The OP should remember that while there are many frequency analysis displays that can be used with a pc most of them display white noise as a horisontal line and pink noise as a line that slopes with -3 dB pr. octave. It may be unwise to measure loudspeakers with white noise .... I haven't got a DEQ, but I think it has measurement analysis built in, other folks know a lot more about it. The extra AD-DA conversion may be unattracive .... but it may also be avoidable, depending on actual context. Kind regards Peter Larsen |
#21
Posted to rec.audio.tech
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Bose 901 EQ distortion
Richard Crowley wrote:
"GregS" wrote... "Richard Crowley" wrote: Is the curve of the Bose EQ box published anywhere? I think I saw it on the patent. Anyway, its flat from 100 to about 2 kHz. There is up to an 18 dB peak at 30 Hz, and a 12 dB peak at 12 kHz. Essentially, most everything is lost above 12 kHz. Studio sound mentioned 22 dB of eq, which lead to it being impossible for Hugh Ford to measure on the eq version they tested because 1 volt input at 20 kHz caused clipping. I can't get into detail, the paper the print was on has been recycled long time ago. That would make a bullhorn or a telephone sound good! :-) We have to take this in stages, first we teach him what a good EQ is, next he begins to wonder - like everybody else - about the wisdom of using midrange units for full range audio. It is no good to just flame the boseaholics, they need to be taught. It is of course cheaper to just replace the loudspeakers without getting another eq or getting the broken one fixed, except that Bose reportedly will take a look on the actual eq box and fix it if broken. In the real life, outside the world of the brochures, many loudspeaker-room combinations will benefit from eq, but as a general guideline something is broken or ill applied if more than 6 dB boost is relevant, narrow 8 db cuts may be very relevant in the low range in rooms that have no low range acoustics regulation, ie. bass traps. Kind regards Peter Larsen |
#22
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Bose 901 EQ distortion
I have 33 Bose 102 ceiling speakers installed as under-balcony delay in the
theater where I work. It had a 102 system processor and analog eq/delay units when originally installed. When the processing was replaced with a BSS minidrive, the guy who eventually RTA'ed the room said he took a sample of the 102's EQ pattern by sending a pink noise signal through it and analyzed the output signal to see what kind of curve the processor provided and used this as the basis for the minidrives programming "flatline" and then correcting for room response with the rta. Could you take a new "DSP box" and analyzer and make your own "901 EQ"? Chris "Peter Larsen" wrote in message ... Richard Crowley wrote: Is the curve of the Bose EQ box published anywhere? It looks like the image of a gletcher valley cross-section ... Someone over in a.a.p.l-s linked to an image of an analysis of it, i have it somewhere on some harddisk, mostly I think it was about the 802's ... but in case of the deq one just needs a measuring microphone and to aim for the b&k living room reference curve, the simplified version is flat up to 200 Hz and then drops smoothly to -6 dB at 20 kHz, aiming for perfection at the extremes is folly. The OP should remember that while there are many frequency analysis displays that can be used with a pc most of them display white noise as a horisontal line and pink noise as a line that slopes with -3 dB pr. octave. It may be unwise to measure loudspeakers with white noise .... I haven't got a DEQ, but I think it has measurement analysis built in, other folks know a lot more about it. The extra AD-DA conversion may be unattracive .... but it may also be avoidable, depending on actual context. Kind regards Peter Larsen |
#23
Posted to rec.audio.tech
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Bose 901 EQ distortion
"Chris Kidd" wrote in ...
I have 33 Bose 102 ceiling speakers installed as under-balcony delay in the theater where I work. It had a 102 system processor and analog eq/delay units when originally installed. When the processing was replaced with a BSS minidrive, the guy who eventually RTA'ed the room said he took a sample of the 102's EQ pattern by sending a pink noise signal through it and analyzed the output signal to see what kind of curve the processor provided and used this as the basis for the minidrives programming "flatline" and then correcting for room response with the rta. Could you take a new "DSP box" and analyzer and make your own "901 EQ"? Dunno why not. A speaker is a speaker, whether it says Bose on it or not. The bottom line is what it sounds like in the audience area, so RTA'ing the room may be a good solution to dealing with whatever wierdness of Bose drivers. |
#24
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#26
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Quote:
I got bad issues because of that, yeah you are right i think new CD players shouldn't do this |
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