hi there swez ..... i hav this amp which you already reviewed in the topic "help pls....underpowered amp". ive a follow up question about its bass boost. it is a dial type and ranges 0 - 18db. as i rotate the dial (clockwise), i noticed that i dont hear any boost from 0 to its halfway point (12o'clock). the bass only starts to get louder past half the dial. could it be then that 0 db is set at its half way point? i hope you could giv me an idea here cause i dont know where in the dial is 3db, 6db etc.... it just ses 0db-18db.
Replies (15)
Ash on 07/19/2006 21:14:14
Where the dial sits does not really matter as the markings aren't usually acccurate. What is important that it is set to where satisfactory results are attained without over stressing the amp or sub.
Normally, no more than + 3-6 db boost should be used. If you require more than that the sub/box combo should be re-evaluated to maximize low end output. Using too much boost can cause a peak in response around the centered frequency with less output above & below it, thus resulting in a undesirable "one note bass".
swez on 07/19/2006 23:01:53
Could not have said it better there Ash! ;-)
Most amps have the Bass Boost centered at 45 Hz. If you cannot hear much difference between 0 - midpoint when using the boost feature, it probably has more to do with low quality filters and preamps in that circuit.
As Ash puts it so well, if you want more low end bump, we need to look more closely at the sub, its enclosure aspects and the amp used.
Swez
PS Give us more details about the amp, sub and enclosure used. I looked at you previous postings and did not see any brands, model #'s or other key details about your gear. Thanks!
sentradzl on 07/20/2006 00:49:47
i think the amp is generic...it doesnt hav a brand.
MGT POWER
ptr-2200 RMS 50w x 2
fuse is 25 amperes
here's the measurement. it might give you an idea of the circuitry inside. ( i just thought, the bigger the amp, the higher the power it gives :) ) 9in. x 7in. x 2 in.
12 inch sub is dvc 400w @ 4 ohms each voice coil....
box is 1 cu ft sealed
Ash on 07/20/2006 20:36:59
I ran a decent search on any brand possibly with that name. Chances are this is a company that doesn't list for various reasons. With a 25 amp fuse, you would think it could have at least some mediocre output. Size of the heatsink or weight is not necessarily a factor.
Either way, with that sub, I doubt very seriously that it can run it being that it would have to be 2 ohm stable bridged. You may have to ditch that amp and revamp your setup to attain good results. What sub are you running?
MrBrownstone on 07/21/2006 05:11:17
A little side note on those bass boosts...the reason you don't notice much difference when you rotate the knob from 0-6 dB or so is that there really isn't that much information below 45Hz...AND, you get a good idea just how little double & quadruple the power really is to a system.
Also, keep in mind, if there's no information at or around 45Hz, then you won't notice ZERO being amplified to 4 X ZERO
Generic Amp? Must be an Anaba or Audiobahn product :-)
swez on 07/21/2006 13:19:30
If this amp has a High Pass Filter network, it may be useful to power front speakers. The power this amp is likely to deliver breaks down like this:
1. 50 watts RMS x 2 @ 4 ohms per channel
2. 100 watts RMS x 2 @ 2 ohms per channel
2. Bridged Mono, 200 watts RMS @ 4 ohms x 1 channel
If you used 2 ohm full range speakers up front, this amp should be adequate to power them well enough.
For your sub, what brand and model number is it? Knowing that, we can give you some ideas on what amps will give you some nice bump for reasonable prices.
Swez
PS What version Sentra is this? Hatchback, Sport Coupe, Sedan or Station wagon? Also, what HU are you using at the moment? (Stock or Aftermarket?) If an Aftermarket HU, make and model please.
sentradzl on 07/25/2006 19:56:17
car is a nissan sentra sedan type. single sub on a sealed box firing backwards/ upwards(?) 45 degrees angle
the HU is KENWOOD RX-380 fm/cassette player w/ separate cd player w/c is KENWOOD RD-380 there you go....:)
as of now, my front speakers are wired directly to the head unit leaving the amp powering solely the sub. still, those front speakers play loud enough. im planning now to wire my sub in mono 2ohms and get that 200 watts but set it to full range. but would that be a too much load for my "tiny" amp? im not gonna be playing this system too much loud anyway....
here's what's written on the sub's package...
KONZERT KW-3000M
* 30 hz. - 2000 hz. frequency response
* max. 400 watts
* 93 db SPL
* dual impedance
* high damping rubber surround
* 50 mm high temperature pasv voice coil
* 50 oz. magnet
Ash on 07/25/2006 20:53:30
It is not the volume that will present a problem, it is the resistance the 2 ohm load will have on the amp. Even full range will not help. In fact, it will worsen as power will be spread out over a broad range, thus making the amp work harder.
I've continued looking up these brands that your'e using. Seems like they are made overseas (China) with use as such. I can't say for a fact that they aren't up to par, for no specs can be found. This just makes it hard to say what these products can do. For all we know, the box may not even be right for the sub.
If you want real control over the use of equipment, I suggest you choose something that at least provides true specs (theile/small parameters). Then it will be easier to see what is possible.
swez on 07/26/2006 09:45:14
Thanks for the product info. I did find an install/spec manual for this HU, but it's in Japanese. I cannot read Japanese. However, the pictures in the manual provide enough detail, (and humorous pics) to make it worth reviewing in anyway.
http://www.kenwood-service.com/imdl/car/B64-1829-00.pdf
Best I can tell, this HU has some pretty decent features and typical specs. It looks like only 1 RCA pair are used in this HU and the RCA ouput voltage is very low at that. (1.8 Volts @ 10KOhms or about 1.0 volts @ 20KOhms)
If you want to use that 2 channel amp for your sub, the safest route is to use 1 channel per coil. DO NOT BRIDGE THIS AMP & RUN IT AT 2 OHMS !!! (This will heat the amp up and probably fry it)
Again, if you want to get the most form this system, get a Class D sub amp for the sub. (200 -250 RMS is adequate for this one) Then, use the 2 channel for powering your front speakers. This plan should give you more clean power to the front speakers and adequate power for the sub as well.
NOTE: Since this HU only has 1 pair of RCA's, (Confirm that one please) you can run your sub amp off rear speaker lines, using an amp that has a dual input feature. (RCA or Speaker level inputs)
Swez
sentradzl on 07/26/2006 12:52:12
yes it has only 1 pair of RCA's....i guess im enlightened..and praises to you guys ,....thanks/
swez on 07/26/2006 14:57:23
CLAP
There are a few work-a-round options here. If you want more ideas, just ask.
Swez
sentradzl on 07/26/2006 22:29:50
HU RCA output very low? then running my sub amp off rear speaker lines , i get better results? yes, my amp has a dual input feature.
(additional info) RCA output is controlled by fader. signal comes from rear only.
i wanna get the best out of this system w/out adding another amp. car's battery and alternator are stock. this car is a daily driver. additional unit/s to my system would mean more work for my bat and alternator, right? not to mention, im much too low budgetwise. i really am stucked with this "small" system. :)
swez on 07/27/2006 12:10:22
The HU RCA signal is a bit low, but most amps can compensate by matching the amps' gain settings to whatever the HU RCA's can deliver. In this case, your amp gain sensitivity settings will need to be adjusted in a range between 1.0 - 2.0 volts. Most amps can handle as low as 1/4 volts, (250 milli-volts) to 4-6 volts of input to the RCA's.
If using the high signal input side of the amp, the amplifer will accept 8-10 volts input off the rear speakers and bring that voltage down to a managable level. Again, the amp gain control feature is the proper tool to balance sub output to the full range speakers.
Since this HU has only 1 pair of RCA's and they are fade controlled off the rear channels, they can be used for a sub, amplifying rear stage speakers or both. If you desired to amp the front speakers later, (highly recommended when budget permits) come back and ask about Tri-mode amplification, "passive" woofer filtering and using a "Line Out Convertor" (LOC).
Yes, this all sounds very technical and such, but we'll break things down in easily managable terms you will understand. ;-)
Swez
sentradzl on 07/27/2006 16:34:49
when you say gain sensitivity range between 1.0 - 2.0 volts, visually, where would that be in my dial? 1/4? 1/2?...3/4?
as for latest settings in my system, here's what i did...
* no bass boost
* gain is at 1/2
* filter set to full range....<<<< made vocals richer compared to if set to low pass (something to do with the in-car environment, maybe). also added some tightness in the bass ( have had a hard time where to set the frequency range when set to low pass :) ). i dont know, maybe ill stick to this for a while if you say a "go" to this. if this can be ok, i need your suggestion on where the gain should be set to....
swez on 07/27/2006 20:39:50
Amp gain settings can be done by ear for the most part, or use an AC Voltmeter to measure amp output to sub directly off the amp output lugs. The goal is to have clean, natural and un-distorted audio signals from the speakers or sub used.
Gain Control Settings:
Most amps have a variable gain setting knob or screw head. The Minimum sensitivity setting, (quietest setting) is usually about 4-6 volts. (7:00 position on most amps) The Maximum sensitivity setting, (loudest setting) is usually under 1/2 volts. (5:00 position on most amps) Midpoint is usually about 2-3 volts. (This will vary from one amp maker to another)
NOTE:
1. Set amp gain control to 12:00 position initially
2. Drop in your fav CD with lots of bass in it
3. Set HU volume to 3/4 of max volume
4. Set all HU tone controls to "0" (No cut/No boost)
5. Set the amp gain at the 12:00 position initially. Then, gradually tweak it toward the 5:00 position. The amp will play louder as you adjust the dial clockwise. When you begin to hear distortions, go counter-clockwise a few degrees until everything sounds clean and crisp.
6. Now go back and reset your tone controls for best performance
7. If you hear the amped speakers/sub getting highly distorted audio signals, back off on the amp gain a wee-bit more until everything is clean and balanced
For more information on setting amp gains, look here:
1. http://www.clubknowledge.com/Car_Audio_FAQ/?t20
2. http://www.clubknowledge.com/Car_Audio_FAQ/?t3
3. http://akamaipix.crutchfield.com/Manuals/489/489AP400.PDF (pg. 14)
Item #3 shows an amp that is probably very similar to yours. The layout may be a bit different, but the features and general concepts are the same.
Filter settings:
HPF = High pass filter: This filters out the lows to mids/highs. It is usually a variable adjustment that goes from ~60 Hz., - over 1KHz. This is best used for mids and highs only. (Typical settings here are about 80 - 120 Hz.)
LPF = Low pass filter: This blocks mids and highs to the sub. It too is adjustable and typically goes from 40 Hz., - 250 Hz. This selector is used only for subwoofer applications. (Typical setting is 80-100 Hz.)
Bass Boost: Set this at "0) initially. If Bass is weak off the amp, use minimal bass boost to bring up the lows at ~45 Hz. (If you are using the HPF and it's set above 50 Hz., there will be little or no change in bass output until you get up to +12dB or more bass boost)
OK, got all that?
Swez
Replies (15)
Ash on 07/19/2006 21:14:14
Where the dial sits does not really matter as the markings aren't usually acccurate. What is important that it is set to where satisfactory results are attained without over stressing the amp or sub.
Normally, no more than + 3-6 db boost should be used. If you require more than that the sub/box combo should be re-evaluated to maximize low end output. Using too much boost can cause a peak in response around the centered frequency with less output above & below it, thus resulting in a undesirable "one note bass".
swez on 07/19/2006 23:01:53
Could not have said it better there Ash! ;-)
Most amps have the Bass Boost centered at 45 Hz. If you cannot hear much difference between 0 - midpoint when using the boost feature, it probably has more to do with low quality filters and preamps in that circuit.
As Ash puts it so well, if you want more low end bump, we need to look more closely at the sub, its enclosure aspects and the amp used.
Swez
PS Give us more details about the amp, sub and enclosure used. I looked at you previous postings and did not see any brands, model #'s or other key details about your gear. Thanks!
sentradzl on 07/20/2006 00:49:47
i think the amp is generic...it doesnt hav a brand.
MGT POWER
ptr-2200 RMS 50w x 2
fuse is 25 amperes
here's the measurement. it might give you an idea of the circuitry inside. ( i just thought, the bigger the amp, the higher the power it gives :) ) 9in. x 7in. x 2 in.
12 inch sub is dvc 400w @ 4 ohms each voice coil....
box is 1 cu ft sealed
Ash on 07/20/2006 20:36:59
I ran a decent search on any brand possibly with that name. Chances are this is a company that doesn't list for various reasons. With a 25 amp fuse, you would think it could have at least some mediocre output. Size of the heatsink or weight is not necessarily a factor.
Either way, with that sub, I doubt very seriously that it can run it being that it would have to be 2 ohm stable bridged. You may have to ditch that amp and revamp your setup to attain good results. What sub are you running?
MrBrownstone on 07/21/2006 05:11:17
A little side note on those bass boosts...the reason you don't notice much difference when you rotate the knob from 0-6 dB or so is that there really isn't that much information below 45Hz...AND, you get a good idea just how little double & quadruple the power really is to a system.
Also, keep in mind, if there's no information at or around 45Hz, then you won't notice ZERO being amplified to 4 X ZERO
Generic Amp? Must be an Anaba or Audiobahn product :-)
swez on 07/21/2006 13:19:30
If this amp has a High Pass Filter network, it may be useful to power front speakers. The power this amp is likely to deliver breaks down like this:
1. 50 watts RMS x 2 @ 4 ohms per channel
2. 100 watts RMS x 2 @ 2 ohms per channel
2. Bridged Mono, 200 watts RMS @ 4 ohms x 1 channel
If you used 2 ohm full range speakers up front, this amp should be adequate to power them well enough.
For your sub, what brand and model number is it? Knowing that, we can give you some ideas on what amps will give you some nice bump for reasonable prices.
Swez
PS What version Sentra is this? Hatchback, Sport Coupe, Sedan or Station wagon? Also, what HU are you using at the moment? (Stock or Aftermarket?) If an Aftermarket HU, make and model please.
sentradzl on 07/25/2006 19:56:17
car is a nissan sentra sedan type. single sub on a sealed box firing backwards/ upwards(?) 45 degrees angle
the HU is KENWOOD RX-380 fm/cassette player w/ separate cd player w/c is KENWOOD RD-380 there you go....:)
as of now, my front speakers are wired directly to the head unit leaving the amp powering solely the sub. still, those front speakers play loud enough. im planning now to wire my sub in mono 2ohms and get that 200 watts but set it to full range. but would that be a too much load for my "tiny" amp? im not gonna be playing this system too much loud anyway....
here's what's written on the sub's package...
KONZERT KW-3000M
* 30 hz. - 2000 hz. frequency response
* max. 400 watts
* 93 db SPL
* dual impedance
* high damping rubber surround
* 50 mm high temperature pasv voice coil
* 50 oz. magnet
Ash on 07/25/2006 20:53:30
It is not the volume that will present a problem, it is the resistance the 2 ohm load will have on the amp. Even full range will not help. In fact, it will worsen as power will be spread out over a broad range, thus making the amp work harder.
I've continued looking up these brands that your'e using. Seems like they are made overseas (China) with use as such. I can't say for a fact that they aren't up to par, for no specs can be found. This just makes it hard to say what these products can do. For all we know, the box may not even be right for the sub.
If you want real control over the use of equipment, I suggest you choose something that at least provides true specs (theile/small parameters). Then it will be easier to see what is possible.
swez on 07/26/2006 09:45:14
Thanks for the product info. I did find an install/spec manual for this HU, but it's in Japanese. I cannot read Japanese. However, the pictures in the manual provide enough detail, (and humorous pics) to make it worth reviewing in anyway.
http://www.kenwood-service.com/imdl/car/B64-1829-00.pdf
Best I can tell, this HU has some pretty decent features and typical specs. It looks like only 1 RCA pair are used in this HU and the RCA ouput voltage is very low at that. (1.8 Volts @ 10KOhms or about 1.0 volts @ 20KOhms)
If you want to use that 2 channel amp for your sub, the safest route is to use 1 channel per coil. DO NOT BRIDGE THIS AMP & RUN IT AT 2 OHMS !!! (This will heat the amp up and probably fry it)
Again, if you want to get the most form this system, get a Class D sub amp for the sub. (200 -250 RMS is adequate for this one) Then, use the 2 channel for powering your front speakers. This plan should give you more clean power to the front speakers and adequate power for the sub as well.
NOTE: Since this HU only has 1 pair of RCA's, (Confirm that one please) you can run your sub amp off rear speaker lines, using an amp that has a dual input feature. (RCA or Speaker level inputs)
Swez
sentradzl on 07/26/2006 12:52:12
yes it has only 1 pair of RCA's....i guess im enlightened..and praises to you guys ,....thanks/
swez on 07/26/2006 14:57:23
CLAP
There are a few work-a-round options here. If you want more ideas, just ask.
Swez
sentradzl on 07/26/2006 22:29:50
HU RCA output very low? then running my sub amp off rear speaker lines , i get better results? yes, my amp has a dual input feature.
(additional info) RCA output is controlled by fader. signal comes from rear only.
i wanna get the best out of this system w/out adding another amp. car's battery and alternator are stock. this car is a daily driver. additional unit/s to my system would mean more work for my bat and alternator, right? not to mention, im much too low budgetwise. i really am stucked with this "small" system. :)
swez on 07/27/2006 12:10:22
The HU RCA signal is a bit low, but most amps can compensate by matching the amps' gain settings to whatever the HU RCA's can deliver. In this case, your amp gain sensitivity settings will need to be adjusted in a range between 1.0 - 2.0 volts. Most amps can handle as low as 1/4 volts, (250 milli-volts) to 4-6 volts of input to the RCA's.
If using the high signal input side of the amp, the amplifer will accept 8-10 volts input off the rear speakers and bring that voltage down to a managable level. Again, the amp gain control feature is the proper tool to balance sub output to the full range speakers.
Since this HU has only 1 pair of RCA's and they are fade controlled off the rear channels, they can be used for a sub, amplifying rear stage speakers or both. If you desired to amp the front speakers later, (highly recommended when budget permits) come back and ask about Tri-mode amplification, "passive" woofer filtering and using a "Line Out Convertor" (LOC).
Yes, this all sounds very technical and such, but we'll break things down in easily managable terms you will understand. ;-)
Swez
sentradzl on 07/27/2006 16:34:49
when you say gain sensitivity range between 1.0 - 2.0 volts, visually, where would that be in my dial? 1/4? 1/2?...3/4?
as for latest settings in my system, here's what i did...
* no bass boost
* gain is at 1/2
* filter set to full range....<<<< made vocals richer compared to if set to low pass (something to do with the in-car environment, maybe). also added some tightness in the bass ( have had a hard time where to set the frequency range when set to low pass :) ). i dont know, maybe ill stick to this for a while if you say a "go" to this. if this can be ok, i need your suggestion on where the gain should be set to....
swez on 07/27/2006 20:39:50
Amp gain settings can be done by ear for the most part, or use an AC Voltmeter to measure amp output to sub directly off the amp output lugs. The goal is to have clean, natural and un-distorted audio signals from the speakers or sub used.
Gain Control Settings:
Most amps have a variable gain setting knob or screw head. The Minimum sensitivity setting, (quietest setting) is usually about 4-6 volts. (7:00 position on most amps) The Maximum sensitivity setting, (loudest setting) is usually under 1/2 volts. (5:00 position on most amps) Midpoint is usually about 2-3 volts. (This will vary from one amp maker to another)
NOTE:
1. Set amp gain control to 12:00 position initially
2. Drop in your fav CD with lots of bass in it
3. Set HU volume to 3/4 of max volume
4. Set all HU tone controls to "0" (No cut/No boost)
5. Set the amp gain at the 12:00 position initially. Then, gradually tweak it toward the 5:00 position. The amp will play louder as you adjust the dial clockwise. When you begin to hear distortions, go counter-clockwise a few degrees until everything sounds clean and crisp.
6. Now go back and reset your tone controls for best performance
7. If you hear the amped speakers/sub getting highly distorted audio signals, back off on the amp gain a wee-bit more until everything is clean and balanced
For more information on setting amp gains, look here:
1. http://www.clubknowledge.com/Car_Audio_FAQ/?t20
2. http://www.clubknowledge.com/Car_Audio_FAQ/?t3
3. http://akamaipix.crutchfield.com/Manuals/489/489AP400.PDF (pg. 14)
Item #3 shows an amp that is probably very similar to yours. The layout may be a bit different, but the features and general concepts are the same.
Filter settings:
HPF = High pass filter: This filters out the lows to mids/highs. It is usually a variable adjustment that goes from ~60 Hz., - over 1KHz. This is best used for mids and highs only. (Typical settings here are about 80 - 120 Hz.)
LPF = Low pass filter: This blocks mids and highs to the sub. It too is adjustable and typically goes from 40 Hz., - 250 Hz. This selector is used only for subwoofer applications. (Typical setting is 80-100 Hz.)
Bass Boost: Set this at "0) initially. If Bass is weak off the amp, use minimal bass boost to bring up the lows at ~45 Hz. (If you are using the HPF and it's set above 50 Hz., there will be little or no change in bass output until you get up to +12dB or more bass boost)
OK, got all that?
Swez
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