the jbl 600.1 has an input sensitivity of 250mv-4v if I have a HU that has 5V preamp out puts, does that matter?
Replies (15)
uochronos on 04/24/2004 05:11:01
i have a hu with i believe its a 5 or 6v preamp out puts and my amp has 250-4v and i have never ahd a problem. i myself am still a bit fuzzy about where it should be set in this situation but i know it well work.
Tinker18 on 04/24/2004 11:40:38
i wasnt sure whether or not it will affect it but i was curious. SWEZ, if your reading this please answer it.
swez on 04/24/2004 19:54:12
Set your gain at 4 volts and see how well the sub(s) perform at that gain setting.
The HU will not actually reach a full 5.0 volts until your HU volume is about 60-75% of MAX. (depends on how much bass boost is used on your HU as well.
Swez
Tinker18 on 04/24/2004 20:32:54
ok, but what happens after i turn it up that loud? clipping? what something. if the hu is putting out 5v of signal and the amp only responds to 4?
swez on 04/25/2004 12:19:30
Yes, if you have the amp gain set at 4.0 volts and try to feed it 5 or more volts, the amp will begin to clip as the input preamp is being overdriven. If this becomes a real noticable problem and the amp is clipping a lot, you can buy and install a -3dB input attenuator module between HU and amp input.
A -3dB attenuator will knock down your input voltafe from 5.0 volts to ~ 2.5 volts to amp. Readjust your input gain and you are good to go.
Harrison Labs: http://www.thezeb.com/detail.aspx?ID=1698
Swez
cybersailor420 on 04/25/2004 13:01:52
hey swez, i'm still a little confused on this issue. first of all, where do you measure what your gain is set at?
as you mentioned above, it is not good to send more volts through the inputs than what your gian is set at. Can you leave your gain set a little higher? For example, couldn't Tinker just leave his gain set at 5 volts, and then he wouldn't have to worry about clipping when he turned the volume up?
this is one area i have never been very clear on. hopefully you can change that. thanx again.
-Ian-
Tinker18 on 04/25/2004 13:08:38
im not very clear on that issue either, thanks lan, you read my mind, but this is something i have yet to understand. if i get a HU that only sends a 4v preamp signal, would that be better? seing as how i havent bought the HU yet?br
swez on 04/26/2004 11:54:24
The JBL Power Valve series has a gain control that is adjustable between 250mV (1/4 volt) to 4.0 volts. There are markings on the gain adjustment knob/pot that give a reference number for setup. Midpoint is about 2.0 volts.
The gain control is not a volume control per-se. It is an input voltage regulator that helps set the amp power to optimal output, based on input signal levels from the source. (HU, CD or MP3 player) Most HU's will have an RCA output voltage reference between 1-6 volts. But the maximum voltage specified,will not be attained until the HU is running at ~60-70% of max output.
For the most part, this is all done by "feel and listening" carefully for distortion in subs as the power at HU is increased. Most folks don't have a dual channel O-scope to measure input signal voltage to amp on one channel & amp output waveforms. So, tuning by ear, is your only recourse.
Basically, you want to match your gain setting to the HU output voltage. If amp gain is set too low, (1.0 volt) and you feed the amp 4 volts, the amp will reach full output at 1 volt and clip above ~1.0 volts input. It may sound louder, but much more distortion is hear from subs.
Does that help answer your questions?
Swez
PS For this sub amp, try to use a HU with RCA output voltage between 2.0 - 4.0 volts if possible
devastating12s on 04/26/2004 14:57:12
I have a question about this..
say for instance your HU puts out 2V and you set the amp gain to 2v.
now what if another HU has an output of say.. 4v and you appropriately set the amp gain to 4v.
which scenario would yield more clean power from the amps to the subs? Or are they both the same? Or am I totally off?
Tinker18 on 04/26/2004 18:00:00
well, one thing I know about that, is that, the higher the preamp voltage on the HU the cleaner the signal is. I was originally going to buy an Kenwood HU with 5v pre amps, but now i have changed my mind to the Alpine CDA-9833 which is normally around 450-500 bucks, but i am going to get it at stereo-fx for 300 flat. good deal eh?
saintanddolphin on 04/26/2004 21:33:15
Hi Mike,
Thanks for your inquiry to us. If your head units maximum output voltage
is 5 volts, I would highly recommend that you keep the voltage settings
for sensitivity at its minimum. By doing this you will reduce the chance
of over driving the input due to high signal level input. Ultimately,
the best way to balance the amplifier input sensitivity is the use a
signal generator or test cd with frequency data, a digital volt/ohm
meter and an oscilloscope. With these tools you will be able to balance
the amplifier to the signal output of your head unit and therefore never
subject your system to signal overload conditions.
Best Regards,
Ed Carter, Jr.
Web Support Specialist HK / JBL / Infinity
I e-mailed JBL about the 600.1 specifically and this was there response.I did not post right away because a Gold was addressing it.(Swez)
I am posting it now because of the response to this post and the intrest of it.Its a great technical topic.
JBL isnt saying anything different than Swez but just thought I would throw it in.
Mike
cybersailor420 on 04/26/2004 22:13:29
so basically, unless you have professional tools, or have a professional do it for you, there is no real precise way to match the amp gain to the voltage on the pre-outs? just do it by listening...
-Ian-
swez on 04/26/2004 23:34:18
I was going to post in more detail on testing your system for precise gain settings... but since most guys do not have that kind of test equipment lying around, tuning by ear is an acceptable fall back position.
Of coarse, that assumes one has a well tuned ear and can detect an amp that is in the clipping mode on a regular basis. I can do that as I have been at this a long time... but some of our readers don't have that experience yet. But if you are a careful listener... it it definitely noticable when the amp begins to clip... be it full range or sub applications.
For Dev12: The net result is the same as long as the gain settings match the HU output. A 4 volt HU will deliver more signal and less noise to the amp. That's the main advantage of higher output HU's. But if you have a 2 volt HU, setting the amp gains at 2 volts will net the same output power from the amp. That why most amp have variable gain controls... to accomodate the vast array of HU's that are out there today.
Hope this answers the issues that cloud our understanding on this subject. Saint's response from JBL Tech is right on target. Unfortunately, most of us don't have that kind of test gear at hand.
Swez
PS I wish I knew the input impedance of a JBL amp. Then a voltmeter and resistors can be used to tweak our amps more precisely. It could be anywhere between 10Kohms and up???
cplkittle on 04/27/2004 09:01:14
One other thing to consider..
Most head units advertise the combined output voltage of all RCA preouts. There are only two that I know of that distinctly say #V preout per channel. So if your HU says 6v preout, and you have 6 RCA outputs, more than likely you have 1V each. While it is considered optimum to match input sensitivity with preout voltage, most of the time this results in overwhelming volume. I see alot of high dollar amplifiers (JL, Diamond) that don't even have voltage markings on the sensitivity adjustment. If you can't access or afford to have your equiptment tested with the proper equiptment, your best bet is to do it by ear, or have someone that does it for a living adjust it for you. We adjust amps by ear all the time for free. believe it or not there are alot of people that install their own stuff and bring it by here to be adjusted. The only thing you need to listen for is clipping. Normal listening volume should be equal to 25% of the HU's maximum volume range. ie if your HU volume goes up to 60, set the volume on 15 and adjust the gain to what you consider normal volume. This should shift most of the load to the amplifier and reduce the chances of sending a clipped signal from the HU to the amplifier.
I know this is echoing alot of what Swez has already said, but I had to put it all together to include my 2 cents :)
swez on 04/27/2004 15:21:02
Good summary there Kit & Saint... I hope this post is more helpful than confusing to the readers.
Train your ears or take it to one that has that knowlede for you. If one is super SQ minded, have a Pro do the whole setup with an O-Scope and meter. Ask to watch if possible as you will see the process in action and also hear an optimized system at the same time.
Swez COFFEE
Replies (15)
uochronos on 04/24/2004 05:11:01
i have a hu with i believe its a 5 or 6v preamp out puts and my amp has 250-4v and i have never ahd a problem. i myself am still a bit fuzzy about where it should be set in this situation but i know it well work.
Tinker18 on 04/24/2004 11:40:38
i wasnt sure whether or not it will affect it but i was curious. SWEZ, if your reading this please answer it.
swez on 04/24/2004 19:54:12
Set your gain at 4 volts and see how well the sub(s) perform at that gain setting.
The HU will not actually reach a full 5.0 volts until your HU volume is about 60-75% of MAX. (depends on how much bass boost is used on your HU as well.
Swez
Tinker18 on 04/24/2004 20:32:54
ok, but what happens after i turn it up that loud? clipping? what something. if the hu is putting out 5v of signal and the amp only responds to 4?
swez on 04/25/2004 12:19:30
Yes, if you have the amp gain set at 4.0 volts and try to feed it 5 or more volts, the amp will begin to clip as the input preamp is being overdriven. If this becomes a real noticable problem and the amp is clipping a lot, you can buy and install a -3dB input attenuator module between HU and amp input.
A -3dB attenuator will knock down your input voltafe from 5.0 volts to ~ 2.5 volts to amp. Readjust your input gain and you are good to go.
Harrison Labs: http://www.thezeb.com/detail.aspx?ID=1698
Swez
cybersailor420 on 04/25/2004 13:01:52
hey swez, i'm still a little confused on this issue. first of all, where do you measure what your gain is set at?
as you mentioned above, it is not good to send more volts through the inputs than what your gian is set at. Can you leave your gain set a little higher? For example, couldn't Tinker just leave his gain set at 5 volts, and then he wouldn't have to worry about clipping when he turned the volume up?
this is one area i have never been very clear on. hopefully you can change that. thanx again.
-Ian-
Tinker18 on 04/25/2004 13:08:38
im not very clear on that issue either, thanks lan, you read my mind, but this is something i have yet to understand. if i get a HU that only sends a 4v preamp signal, would that be better? seing as how i havent bought the HU yet?br
swez on 04/26/2004 11:54:24
The JBL Power Valve series has a gain control that is adjustable between 250mV (1/4 volt) to 4.0 volts. There are markings on the gain adjustment knob/pot that give a reference number for setup. Midpoint is about 2.0 volts.
The gain control is not a volume control per-se. It is an input voltage regulator that helps set the amp power to optimal output, based on input signal levels from the source. (HU, CD or MP3 player) Most HU's will have an RCA output voltage reference between 1-6 volts. But the maximum voltage specified,will not be attained until the HU is running at ~60-70% of max output.
For the most part, this is all done by "feel and listening" carefully for distortion in subs as the power at HU is increased. Most folks don't have a dual channel O-scope to measure input signal voltage to amp on one channel & amp output waveforms. So, tuning by ear, is your only recourse.
Basically, you want to match your gain setting to the HU output voltage. If amp gain is set too low, (1.0 volt) and you feed the amp 4 volts, the amp will reach full output at 1 volt and clip above ~1.0 volts input. It may sound louder, but much more distortion is hear from subs.
Does that help answer your questions?
Swez
PS For this sub amp, try to use a HU with RCA output voltage between 2.0 - 4.0 volts if possible
devastating12s on 04/26/2004 14:57:12
I have a question about this..
say for instance your HU puts out 2V and you set the amp gain to 2v.
now what if another HU has an output of say.. 4v and you appropriately set the amp gain to 4v.
which scenario would yield more clean power from the amps to the subs? Or are they both the same? Or am I totally off?
Tinker18 on 04/26/2004 18:00:00
well, one thing I know about that, is that, the higher the preamp voltage on the HU the cleaner the signal is. I was originally going to buy an Kenwood HU with 5v pre amps, but now i have changed my mind to the Alpine CDA-9833 which is normally around 450-500 bucks, but i am going to get it at stereo-fx for 300 flat. good deal eh?
saintanddolphin on 04/26/2004 21:33:15
Hi Mike,
Thanks for your inquiry to us. If your head units maximum output voltage
is 5 volts, I would highly recommend that you keep the voltage settings
for sensitivity at its minimum. By doing this you will reduce the chance
of over driving the input due to high signal level input. Ultimately,
the best way to balance the amplifier input sensitivity is the use a
signal generator or test cd with frequency data, a digital volt/ohm
meter and an oscilloscope. With these tools you will be able to balance
the amplifier to the signal output of your head unit and therefore never
subject your system to signal overload conditions.
Best Regards,
Ed Carter, Jr.
Web Support Specialist HK / JBL / Infinity
I e-mailed JBL about the 600.1 specifically and this was there response.I did not post right away because a Gold was addressing it.(Swez)
I am posting it now because of the response to this post and the intrest of it.Its a great technical topic.
JBL isnt saying anything different than Swez but just thought I would throw it in.
Mike
cybersailor420 on 04/26/2004 22:13:29
so basically, unless you have professional tools, or have a professional do it for you, there is no real precise way to match the amp gain to the voltage on the pre-outs? just do it by listening...
-Ian-
swez on 04/26/2004 23:34:18
I was going to post in more detail on testing your system for precise gain settings... but since most guys do not have that kind of test equipment lying around, tuning by ear is an acceptable fall back position.
Of coarse, that assumes one has a well tuned ear and can detect an amp that is in the clipping mode on a regular basis. I can do that as I have been at this a long time... but some of our readers don't have that experience yet. But if you are a careful listener... it it definitely noticable when the amp begins to clip... be it full range or sub applications.
For Dev12: The net result is the same as long as the gain settings match the HU output. A 4 volt HU will deliver more signal and less noise to the amp. That's the main advantage of higher output HU's. But if you have a 2 volt HU, setting the amp gains at 2 volts will net the same output power from the amp. That why most amp have variable gain controls... to accomodate the vast array of HU's that are out there today.
Hope this answers the issues that cloud our understanding on this subject. Saint's response from JBL Tech is right on target. Unfortunately, most of us don't have that kind of test gear at hand.
Swez
PS I wish I knew the input impedance of a JBL amp. Then a voltmeter and resistors can be used to tweak our amps more precisely. It could be anywhere between 10Kohms and up???
cplkittle on 04/27/2004 09:01:14
One other thing to consider..
Most head units advertise the combined output voltage of all RCA preouts. There are only two that I know of that distinctly say #V preout per channel. So if your HU says 6v preout, and you have 6 RCA outputs, more than likely you have 1V each. While it is considered optimum to match input sensitivity with preout voltage, most of the time this results in overwhelming volume. I see alot of high dollar amplifiers (JL, Diamond) that don't even have voltage markings on the sensitivity adjustment. If you can't access or afford to have your equiptment tested with the proper equiptment, your best bet is to do it by ear, or have someone that does it for a living adjust it for you. We adjust amps by ear all the time for free. believe it or not there are alot of people that install their own stuff and bring it by here to be adjusted. The only thing you need to listen for is clipping. Normal listening volume should be equal to 25% of the HU's maximum volume range. ie if your HU volume goes up to 60, set the volume on 15 and adjust the gain to what you consider normal volume. This should shift most of the load to the amplifier and reduce the chances of sending a clipped signal from the HU to the amplifier.
I know this is echoing alot of what Swez has already said, but I had to put it all together to include my 2 cents :)
swez on 04/27/2004 15:21:02
Good summary there Kit & Saint... I hope this post is more helpful than confusing to the readers.
Train your ears or take it to one that has that knowlede for you. If one is super SQ minded, have a Pro do the whole setup with an O-Scope and meter. Ask to watch if possible as you will see the process in action and also hear an optimized system at the same time.
Swez COFFEE
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