Distortion and other faults - audio system
#1
09-24-2018, 07:50 AM
Distortion and other faults - audio system
Hi,
I am a new member and am experiencing some faults with the Radio/Cassette/CD system in my 1996 Convertible XK8:
The audio system in my car is the Hartman Kardon premium system. with boot mounted 6 disc changer and amplifier. A few weeks ago I noticed distortion of the treble frequencies on the right (driver’s) door tweeter which is concealed inside and behind a triangular trim piece which covers the door mirror fixing which is sometimes known as the “cheater trim”. I purchased a replacement secondhand trim and tweeter assembly, and although this initially appeared to cure the fault, The distortion reappeared a day later. I substituted the original tweeter which again cured the fault temporarily. I then purchased a miniature tweeter and filter capacitor and installed this and the distortion persisted, I then disconnected the tweeter and found the distortion still occurring (right front channel only) - and - even more curiously - treble frequencies (distorted) were appearing to emanate from what was now meant to be acting as a woofer only speaker.
in addition to this, the volume level (on all 4 channels simultaneously) increases and decreases as if an invisible finger was gently raising then lowering the volume level by three or four notches.
Any suggestions?
I am a new member and am experiencing some faults with the Radio/Cassette/CD system in my 1996 Convertible XK8:
The audio system in my car is the Hartman Kardon premium system. with boot mounted 6 disc changer and amplifier. A few weeks ago I noticed distortion of the treble frequencies on the right (driver’s) door tweeter which is concealed inside and behind a triangular trim piece which covers the door mirror fixing which is sometimes known as the “cheater trim”. I purchased a replacement secondhand trim and tweeter assembly, and although this initially appeared to cure the fault, The distortion reappeared a day later. I substituted the original tweeter which again cured the fault temporarily. I then purchased a miniature tweeter and filter capacitor and installed this and the distortion persisted, I then disconnected the tweeter and found the distortion still occurring (right front channel only) - and - even more curiously - treble frequencies (distorted) were appearing to emanate from what was now meant to be acting as a woofer only speaker.
in addition to this, the volume level (on all 4 channels simultaneously) increases and decreases as if an invisible finger was gently raising then lowering the volume level by three or four notches.
Any suggestions?
#2
09-24-2018, 09:09 AM
Veteran Member
I've got to think about this one. I'm really surprised you can hear so much from the sail speaker you mentioned. Its a tiny speaker, only plays frequencies from about 6khz and above.
here's another twist. The sail speaker is in parallel with the dashboard speaker, whose sound is much more prominent. Does that one sound ok? If yes the amp and radio would not appear to be suspect, yet that's my first choice of a problem source.
just reread. When you mention acting as a woofer you don't specify which driver you mean. Bottom of door?
John
here's another twist. The sail speaker is in parallel with the dashboard speaker, whose sound is much more prominent. Does that one sound ok? If yes the amp and radio would not appear to be suspect, yet that's my first choice of a problem source.
just reread. When you mention acting as a woofer you don't specify which driver you mean. Bottom of door?
John
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Marqymarquis (09-26-2018)
#3
09-24-2018, 09:32 AM
Audio Distortion
Hi John,
Thanks for your prompt reply.
i assume by “sail speaker” you mean the 25mm approx. diameter tweeter with 3.3uF capacitor in Series with the + wire behind the trim piece which conceals the bolt that holds the door mirror in place? If so, it’s a much more descriptive term than “Door mirror cheater trim” which is what it’s called in a very popular online auction/sales site.Having just checked the wiring diagram in the WSM (CD version) I do note that the squawker In The Top Of The dashboard is parallelled with the “sail speaker” tweeter. As I am 61 years old my high frequency hearing has deteriorated this May be from where I’m hearing the distortion. I will have to listen to it again and post a reply. Yes, the woofer to which I refer is mounted in the door.=Johnken;1966299]I've got to think about this one. I'm really surprised you can hear so much from the sail speaker you mentioned. Its a tiny speaker, only plays frequencies from about 6khz and above.
here's another twist. The sail speaker is in parallel with the dashboard speaker, whose sound is much more prominent. Does that one sound ok? If yes the amp and radio would not appear to be suspect, yet that's my first choice of a problem source.
just reread. When you mention acting as a woofer you don't specify which driver you mean. Bottom of door?
John[/QUOTE]
Thanks for your prompt reply.
i assume by “sail speaker” you mean the 25mm approx. diameter tweeter with 3.3uF capacitor in Series with the + wire behind the trim piece which conceals the bolt that holds the door mirror in place? If so, it’s a much more descriptive term than “Door mirror cheater trim” which is what it’s called in a very popular online auction/sales site.Having just checked the wiring diagram in the WSM (CD version) I do note that the squawker In The Top Of The dashboard is parallelled with the “sail speaker” tweeter. As I am 61 years old my high frequency hearing has deteriorated this May be from where I’m hearing the distortion. I will have to listen to it again and post a reply. Yes, the woofer to which I refer is mounted in the door.=Johnken;1966299]I've got to think about this one. I'm really surprised you can hear so much from the sail speaker you mentioned. Its a tiny speaker, only plays frequencies from about 6khz and above.
here's another twist. The sail speaker is in parallel with the dashboard speaker, whose sound is much more prominent. Does that one sound ok? If yes the amp and radio would not appear to be suspect, yet that's my first choice of a problem source.
just reread. When you mention acting as a woofer you don't specify which driver you mean. Bottom of door?
John[/QUOTE]
#4
09-24-2018, 10:18 AM
Further to reply from Johnken
Hi again John,
Further investigation by disconnection of the dashboard squawker does indeed prove the right door woofer in my car IS only transponding bass frequencies; and reconnection of the “sail speaker” confirms what you say that it is not the source of the distortion as it is barely audible (at least to me)
Although a certain amount of “tizzing” resonance was audible from the squawker; the distortion and volume increase/decrease issues only normally present themselves after at least twenty minutes’ use, I will therefore leave the dashboard squawker in a position that it can be quickly disconnected the next time the faults present themselves.
Thanks again.
Mark
Further investigation by disconnection of the dashboard squawker does indeed prove the right door woofer in my car IS only transponding bass frequencies; and reconnection of the “sail speaker” confirms what you say that it is not the source of the distortion as it is barely audible (at least to me)
Although a certain amount of “tizzing” resonance was audible from the squawker; the distortion and volume increase/decrease issues only normally present themselves after at least twenty minutes’ use, I will therefore leave the dashboard squawker in a position that it can be quickly disconnected the next time the faults present themselves.
Thanks again.
Mark
#5
09-24-2018, 04:08 PM
Veteran Member
Mark, great feedback. I bet the in dash speaker is worn out, maybe speaker surround is crumbling or something.
you made me smile when you mentioned how little sound comes from the sail (named after its shape) speaker. I almost asked you if you were 20 years old in the initial response -).
glad the door speaker works as it should.
I believe the grill over the dash speaker just prys up and off. Probably hard to repair, but others here may have done so it replaced It?
may we assume you feel that you've narrowed it down to a defective dash speaker?
John
you made me smile when you mentioned how little sound comes from the sail (named after its shape) speaker. I almost asked you if you were 20 years old in the initial response -).
glad the door speaker works as it should.
I believe the grill over the dash speaker just prys up and off. Probably hard to repair, but others here may have done so it replaced It?
may we assume you feel that you've narrowed it down to a defective dash speaker?
John
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Marqymarquis (09-26-2018)
#6
09-24-2018, 04:10 PM
Veteran Member
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Marqymarquis (09-26-2018)
#7
09-24-2018, 04:38 PM
Reply#2 to Johnken
Hello again Johnken and thanks for your further reply.
I was able to pry the in-dash mounted squawker out very easily and examine it - certainly no visible damage. As the distortion only sets in after the stystem’s been in use for twenty minutes or so and gets progressively worse the longer it’s used for, I will have to wait and “road test” it, then disconnect the speaker when the distortion sets it.
I’m sincerely hoping this is the faulty component, as a pair of secondhand replacements with the grilles are a relatively reasonable Ł50.
As to the “Phantom Volume Adjustment”, once again this only seems to occur when the system’s been in use for at least 45 minutes; I don’t think it’s a speaker or speakers cutting in and out, as that would present itself as dramatic increases and decreases in volume; and as it’s occurred three or four times I’m fairly sure I’m not operating the steering wheel volume control inadvertently.
My worst fear is it’s the head unit at fault - awkward to remove and very expensive (if available at all) to replace.
I was able to pry the in-dash mounted squawker out very easily and examine it - certainly no visible damage. As the distortion only sets in after the stystem’s been in use for twenty minutes or so and gets progressively worse the longer it’s used for, I will have to wait and “road test” it, then disconnect the speaker when the distortion sets it.
I’m sincerely hoping this is the faulty component, as a pair of secondhand replacements with the grilles are a relatively reasonable Ł50.
As to the “Phantom Volume Adjustment”, once again this only seems to occur when the system’s been in use for at least 45 minutes; I don’t think it’s a speaker or speakers cutting in and out, as that would present itself as dramatic increases and decreases in volume; and as it’s occurred three or four times I’m fairly sure I’m not operating the steering wheel volume control inadvertently.
My worst fear is it’s the head unit at fault - awkward to remove and very expensive (if available at all) to replace.
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#8
09-25-2018, 04:37 AM
XK8 - Distortion and Phantom Volume Alterations
A test this morning of about 20 minutes’ revealed distortion from right AND left fascia/dashboard squawker speakers - although the distortion previously APPEARED to me to be on the right channel, this will probably have been because my high frequency hearing in my left ear is far worse than my right.
My plan is to change both the in-dash squawkers and go from there.
My plan is to change both the in-dash squawkers and go from there.
#9
09-25-2018, 08:50 AM
Veteran Member
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Marqymarquis (09-26-2018)
#10
09-26-2018, 10:47 AM
Audio distortion and Phantom Volume Alteration
[QUOTE=Johnken;1966812]Sounds like a good plan.
Further thoughts, observations and questions:
I read a series of posts by another member whose name I cannot remember who appears to have suffered distortion of the fascia mounted squawker (mid range) speakers. Based on their position in the vehicle, I contend that voice coil overheating is likely - I live in the South East of England, and noted that the fascia speaker was very warm when I removed it two days ago - this in a climate which is mild at best. I’m guessing by the text of the other person who suffered this problem that he is in America. I note he had to source alternative aftermarket speakers to replace the Harman Kardons.
My next contention is that the distortion from which my system is suffering is unlikely to be from the head unit (meaning the in-dash radio/cassette unit) because the audio output emanating from this is as a composite signal; i.e. not filtered into bass/mid/treble components - this filtering (or crossover networks) is accomplished within the power amp; and as my distortion is only occurring in the mid range frequencies this points to it being speakers or power amp.
Further thoughts, observations and questions:
I read a series of posts by another member whose name I cannot remember who appears to have suffered distortion of the fascia mounted squawker (mid range) speakers. Based on their position in the vehicle, I contend that voice coil overheating is likely - I live in the South East of England, and noted that the fascia speaker was very warm when I removed it two days ago - this in a climate which is mild at best. I’m guessing by the text of the other person who suffered this problem that he is in America. I note he had to source alternative aftermarket speakers to replace the Harman Kardons.
My next contention is that the distortion from which my system is suffering is unlikely to be from the head unit (meaning the in-dash radio/cassette unit) because the audio output emanating from this is as a composite signal; i.e. not filtered into bass/mid/treble components - this filtering (or crossover networks) is accomplished within the power amp; and as my distortion is only occurring in the mid range frequencies this points to it being speakers or power amp.
#11
09-26-2018, 01:38 PM
Veteran Member
You know irs probably easy enough to connect a known good driver (speaker) to either the squawker connection, or even easier- to the sail speaker on the amp side of the capacitor. That'll give you everything the in dash speaker is seeing.
you know what, just connect to the sail with capacitor out of signal path.
if it sounds good = defective in dash driver. If distortion = amp or head unit issue. Let's start there.
just checking, you are listening at normal volume levels without boosting treble all the way right?
john
you know what, just connect to the sail with capacitor out of signal path.
if it sounds good = defective in dash driver. If distortion = amp or head unit issue. Let's start there.
just checking, you are listening at normal volume levels without boosting treble all the way right?
john
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Marqymarquis (09-26-2018)
#12
09-26-2018, 03:06 PM
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Marqymarquis (09-26-2018)
#13
09-26-2018, 07:17 PM
Distortion and Phantom Volume Alterations
Substitution is what I would normally try, but sad to say I don’t have a known good speaker spare for the task. The replacements I have ordered should arrive soon.
There is a suitable amp for my car available for Ł50.
On another matter, how does one start a new thread on this site?
#14
09-26-2018, 07:26 PM
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09-27-2018, 12:49 PM
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09-27-2018, 01:33 PM
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09-27-2018, 04:58 PM
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