Hertz or JL DSP?

JoeCarSeller · 01-07-2019, 06:53 PM

I'm getting close to a full Bose replacement. I have the PAC interface and plan on using toslink optical for output to be able to run this speaker setup:

Front doors 6.5" components with 1" tweeters in the dash
Rear panels 6.5" two way speakers
Rear Deck 6x9 3 ways
Sub 12L7 in sealed box

After searching half the day I came up with the Hertz H8 DSP/DTA, or the JL Twk D8. The JL looks to be better for having time alignment, but the Hertz looks to have more tuning for eQ options, but I'm not sure which would be best. I'm not going full audiophile on this, just using Polk MM components and speakers, and my sub isn't the sound quality sub either, but should be fine in the small sealed box.

Also, is there another way to get the extra rear channel? The PAC interface only gives front, rear, and sub for outputs. I would be open to running it that way to save on some cash now and decide on a DSP in the future. I have an Alpine PDX digital 5 channel amp, an extra JL 4 channel amp, and a PPI sub amp all sitting around collecting dust.

Lastly, when you guys redo the system like this do you disconnect the factory center channel? How much worse would it sound to not use a DSP and just run the stock bose 6x9 with all the other speakers being upgraded?

Thanks!

SilverCamaroVert · 01-07-2019, 07:01 PM

Why not pick one or the other for rear speakers? Do you have passengers back there much?

I'm leaning towards eliminating my rear speakers during my upgrade but I never have rear passengers and don't care about audio for them if I did anyway as we would be talking.

JaxChris · 01-07-2019, 11:28 PM

Without a center channel, you will only be able to set time alignment for a single position. With a center channel, you can align both of the front seats for an equal experience of the vocal and instrumental stages. Bass is difficult to time align anyhow because it is felt as much as it is perceived, so in a full center stage system you will feel and by subconscious association hear the bass from the closest woofers.

If you don't care about any seating position except the driver, then you can eliminate the center channel and set alignment of all speakers on you. The music will sound a little out of phase for the passenger seat.

If this is really a budget system, skip the external DSP. The PAC will give you a good flat output on its' RCA's. Take the rear RCA's and run them to an amp with input selection. You could get an 8 channel amp and use just 5 channels of input.

Each pole (2 channels) on the amp of an appropriate amp will have a switch that you set which input you want to be used on that output. Set channels 5-8 to use inputs 5/6, set your front component crossover to use channel 3/4 on input 3/4 and place your center channel on channel 1 on input 1/2. Do not plug anything into ch2 input or output. Run your sub connection to a separate amp for the sub(s).

The PAC can set some bandpass values to trim the outer reaches. With the amp filters you can do a little extra tweaking just before amplification if you want the rear seats to have different ranges.

Example would be something like the Kicker KXMA800.8. It's 8x50w. Turn off fader on Amp3/4 to share the 5/6 input with 7/8. Use the 10x button to set a large LP filter on the rears that you don't want excessive tweeter on. The rest of your channels should be shaped by the PAC before it reaches the amp.

It's up to you, but on a budget system that isn't going 3-way active, I wouldn't go sinking money into a large DSP unless you plan to make up for it by budgeting cheap, dumb amps. But good luck cramming all of that under the trunk. Cheap dumb amps are usually large A/B's. Invisible systems today are either 1200$ on the budget side or 2000$+ on the medium side. If you want SQ and SPL audiophile, then you're looking at 4k+ because those uber sensitive speakers with reinforced paper cones are big money. You'll spend 1500-2000 on speakers alone before you get to the 600-800 for DSP, still be using the same integration unit to get your clean outputs without making a mess of the harness, and compact super amps plus cap and distribution equipment tacking on another 1500. Don't forget your matting, rings, box, stuffing, speed wire, felt tape, loom, etc.

JoeCarSeller · 01-08-2019, 02:47 PM

Quote:

Originally Posted by JaxChris

Without a center channel, you will only be able to set time alignment for a single position. With a center channel, you can align both of the front seats for an equal experience of the vocal and instrumental stages. Bass is difficult to time align anyhow because it is felt as much as it is perceived, so in a full center stage system you will feel and by subconscious association hear the bass from the closest woofers.

If you don't care about any seating position except the driver, then you can eliminate the center channel and set alignment of all speakers on you. The music will sound a little out of phase for the passenger seat.

If this is really a budget system, skip the external DSP. The PAC will give you a good flat output on its' RCA's. Take the rear RCA's and run them to an amp with input selection. You could get an 8 channel amp and use just 5 channels of input.

Each pole (2 channels) on the amp of an appropriate amp will have a switch that you set which input you want to be used on that output. Set channels 5-8 to use inputs 5/6, set your front component crossover to use channel 3/4 on input 3/4 and place your center channel on channel 1 on input 1/2. Do not plug anything into ch2 input or output. Run your sub connection to a separate amp for the sub(s).

The PAC can set some bandpass values to trim the outer reaches. With the amp filters you can do a little extra tweaking just before amplification if you want the rear seats to have different ranges.

Example would be something like the Kicker KXMA800.8. It's 8x50w. Turn off fader on Amp3/4 to share the 5/6 input with 7/8. Use the 10x button to set a large LP filter on the rears that you don't want excessive tweeter on. The rest of your channels should be shaped by the PAC before it reaches the amp.

It's up to you, but on a budget system that isn't going 3-way active, I wouldn't go sinking money into a large DSP unless you plan to make up for it by budgeting cheap, dumb amps. But good luck cramming all of that under the trunk. Cheap dumb amps are usually large A/B's. Invisible systems today are either 1200$ on the budget side or 2000$+ on the medium side. If you want SQ and SPL audiophile, then you're looking at 4k+ because those uber sensitive speakers with reinforced paper cones are big money. You'll spend 1500-2000 on speakers alone before you get to the 600-800 for DSP, still be using the same integration unit to get your clean outputs without making a mess of the harness, and compact super amps plus cap and distribution equipment tacking on another 1500. Don't forget your matting, rings, box, stuffing, speed wire, felt tape, loom, etc.

Thanks for the input. I already have an alpine PDX 5 Channel that runs 4x100 plus 1x250 for the sub. I also have a spare JL 4 channel amp sitting around, along with an old school PPI amp that’s huge but slams the sub. I’m wanting to use what I already have for amps. I just am not sure I want to get the last set of 6x9 for the rear deck since I already have 4 channels worth of speaker setups. Just wondering if I should disconnect the bose 6x9 or leave them hooked up and use just the alpine amp with 4 channels. I’ve heard the 6x9 in the deck also would be a large improvement. I might just hook it up with the 4 channels I have now and see how it sounds. I’ve just been thinking of doing it once and being done though. I do have 60 sq ft of butyl sound mat.

JaxChris · 01-08-2019, 08:25 PM

You don't need 3-way's in the back shelf. You'll have a bitch of a time centering the vocals with rear super tweeters in the mix. A 2-way coax should be fine there as well.

Is it the Alpine PDX-V9? If so, set the 3/4 input switch to 1/2 and only provide 1 pair of RCA's to input 1/2. You didn't mention the JL amp model, but if it doesn't have a similar input or fader on/off switch, you can just grab RCA 1 female to 2 male splitters to duplicate the single pair of RCA's. If you want some pseudo active behavior without using the passive crossover blocks, use the amp filters and stick inline filters on the tweeters that roll over LP at 4k-5k hz. Use a splitter as well to make the single mono sub RCA a dual mono pair to connect to 5/6 on the Alpine.

The PAC module creates the center channel the same way the Bose amp does -- using the LF and RF channels from the input harness. If you rob those inputs for the PAC, the factory amp isn't getting anything to create the center channel with. Might as well pull the factory amp. If you hook up just the LR and RR to the PAC, then you'll only get the rear and sub channels on the PAC. Then you would need some help from an external DSP because because the full range is on the front channels. Also, the factory amp may burn up from having inputs plugged into the front channels but no speakers connected to them. If you put something in the input, you must hook something up to the matching output.

Hope this answers everything. If not, please continue posting.

01-07-2019, 06:53 PM	#1
JoeCarSeller Drives: 17 Camaro 2ss Join Date: Jun 2018 Location: Saginaw, MI Posts: 12	Hertz or JL DSP? I'm getting close to a full Bose replacement. I have the PAC interface and plan on using toslink optical for output to be able to run this speaker setup: Front doors 6.5" components with 1" tweeters in the dash Rear panels 6.5" two way speakers Rear Deck 6x9 3 ways Sub 12L7 in sealed box After searching half the day I came up with the Hertz H8 DSP/DTA, or the JL Twk D8. The JL looks to be better for having time alignment, but the Hertz looks to have more tuning for eQ options, but I'm not sure which would be best. I'm not going full audiophile on this, just using Polk MM components and speakers, and my sub isn't the sound quality sub either, but should be fine in the small sealed box. Also, is there another way to get the extra rear channel? The PAC interface only gives front, rear, and sub for outputs. I would be open to running it that way to save on some cash now and decide on a DSP in the future. I have an Alpine PDX digital 5 channel amp, an extra JL 4 channel amp, and a PPI sub amp all sitting around collecting dust. Lastly, when you guys redo the system like this do you disconnect the factory center channel? How much worse would it sound to not use a DSP and just run the stock bose 6x9 with all the other speakers being upgraded? Thanks!

01-07-2019, 07:01 PM	#2
SilverCamaroVert Drives: 2019 LT3 RS Convertible Join Date: Sep 2018 Location: New Hampshire Posts: 126	Why not pick one or the other for rear speakers? Do you have passengers back there much? I'm leaning towards eliminating my rear speakers during my upgrade but I never have rear passengers and don't care about audio for them if I did anyway as we would be talking.

01-07-2019, 11:28 PM	#3
JaxChris Drives: '16 2SS GD1 MX0 NPP F55 IO6 Join Date: Jun 2013 Location: Florida Posts: 1,298	Without a center channel, you will only be able to set time alignment for a single position. With a center channel, you can align both of the front seats for an equal experience of the vocal and instrumental stages. Bass is difficult to time align anyhow because it is felt as much as it is perceived, so in a full center stage system you will feel and by subconscious association hear the bass from the closest woofers. If you don't care about any seating position except the driver, then you can eliminate the center channel and set alignment of all speakers on you. The music will sound a little out of phase for the passenger seat. If this is really a budget system, skip the external DSP. The PAC will give you a good flat output on its' RCA's. Take the rear RCA's and run them to an amp with input selection. You could get an 8 channel amp and use just 5 channels of input. Each pole (2 channels) on the amp of an appropriate amp will have a switch that you set which input you want to be used on that output. Set channels 5-8 to use inputs 5/6, set your front component crossover to use channel 3/4 on input 3/4 and place your center channel on channel 1 on input 1/2. Do not plug anything into ch2 input or output. Run your sub connection to a separate amp for the sub(s). The PAC can set some bandpass values to trim the outer reaches. With the amp filters you can do a little extra tweaking just before amplification if you want the rear seats to have different ranges. Example would be something like the Kicker KXMA800.8. It's 8x50w. Turn off fader on Amp3/4 to share the 5/6 input with 7/8. Use the 10x button to set a large LP filter on the rears that you don't want excessive tweeter on. The rest of your channels should be shaped by the PAC before it reaches the amp. It's up to you, but on a budget system that isn't going 3-way active, I wouldn't go sinking money into a large DSP unless you plan to make up for it by budgeting cheap, dumb amps. But good luck cramming all of that under the trunk. Cheap dumb amps are usually large A/B's. Invisible systems today are either 1200$ on the budget side or 2000$+ on the medium side. If you want SQ and SPL audiophile, then you're looking at 4k+ because those uber sensitive speakers with reinforced paper cones are big money. You'll spend 1500-2000 on speakers alone before you get to the 600-800 for DSP, still be using the same integration unit to get your clean outputs without making a mess of the harness, and compact super amps plus cap and distribution equipment tacking on another 1500. Don't forget your matting, rings, box, stuffing, speed wire, felt tape, loom, etc.

01-08-2019, 08:25 PM	#5
JaxChris Drives: '16 2SS GD1 MX0 NPP F55 IO6 Join Date: Jun 2013 Location: Florida Posts: 1,298	You don't need 3-way's in the back shelf. You'll have a bitch of a time centering the vocals with rear super tweeters in the mix. A 2-way coax should be fine there as well. Is it the Alpine PDX-V9? If so, set the 3/4 input switch to 1/2 and only provide 1 pair of RCA's to input 1/2. You didn't mention the JL amp model, but if it doesn't have a similar input or fader on/off switch, you can just grab RCA 1 female to 2 male splitters to duplicate the single pair of RCA's. If you want some pseudo active behavior without using the passive crossover blocks, use the amp filters and stick inline filters on the tweeters that roll over LP at 4k-5k hz. Use a splitter as well to make the single mono sub RCA a dual mono pair to connect to 5/6 on the Alpine. The PAC module creates the center channel the same way the Bose amp does -- using the LF and RF channels from the input harness. If you rob those inputs for the PAC, the factory amp isn't getting anything to create the center channel with. Might as well pull the factory amp. If you hook up just the LR and RR to the PAC, then you'll only get the rear and sub channels on the PAC. Then you would need some help from an external DSP because because the full range is on the front channels. Also, the factory amp may burn up from having inputs plugged into the front channels but no speakers connected to them. If you put something in the input, you must hook something up to the matching output. Hope this answers everything. If not, please continue posting.

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