Adding 4 channel amp to base non Boston mylink system

[Snoman]

Originally Posted by fif_gen_powa

Great post snoman, that Alpine amp looks nice. Buying it from an authorized retailer is out of my budget for now. But something to consider down the road.

I settled on one of the middle of the line new infinity ref amps, able to stack two coupons and got it for $255 shipped. Sonic does 60 day return if I'm not happy with it and they're an authorized dealer so get a 1yr warranty too https://www.sonicelectronix.com/item...REF-4555A.html

Any thoughts on these subs, killer deal buy one get one free https://www.sonicelectronix.com/item...odp=gbmv7uh9d5

There are reputable Alpine resellers on Amazon, albeit going that route does introduce risks that many are not comfortable with. I personally use an Infinity Kappa Reference 4ch A/B amp that is amazing and going strong even after 10 years, hopefully their new line is as good. I had reservations using it, but the HK group basically gave it to me for free.

The NVX subs are complete trash, you won't be happy with them as they only tune to 60hz. If $200 is "in budget", then I would suggest a pair of RF-P2s or the Polk Audio MM1240svc. The Polks are 92db/1m, tune to 42hz and only require 1.3cuft to achieve the fabled perfect Qts of 0.707. You can always start with 1 sub and add another later if you need more bass. There might be an available 12" that tunes lower with comparable specs (doubt it), but all I've seen require substantially more money or larger box size. The Fabled Morel Titanium-4 for example, tunes to 37hz, but costs over $1,000 (only weighs 15lbs though) and while the JL 12W6v3-D4 is a nice compromise, costs $500 and offers significantly lower output (85db) for negligible performance. If any know of any, I'm happy to add them to my database and take a look.

Your target box size for the Polk MM1240svc will be approximately 1.2-1.3.

Qtc Vb Fb F3
0.707 1.301 42.42 42.43
0.725 1.179 43.50 42.45
0.750 1.040 45.00 42.57

Basically, build or purchase a 1.1-1.2 ft^3 / speaker box, add 1 lb of poly fill, drop your speaker in and enjoy. Don't forget, all speakers require "burn in", generally 40 hrs, so be patient after you start up your system.

[fif_gen_powa]

Got the amp installed yesterday, Infinity REF-4555A 5 channel just running the front channel to a set of Infinity 60.11cs components for now. Happy with the sound with minimal tweaking so far. Got a sub on the way and will be adding some rear fill.

Install was a breeze used the PAC harness behind the radio, removed the loc and cut the front channel wires, split them up as one pair from radio, one pair to front speakers, than ran a "9 wire" back to amp. 4 wires for front speaker level input for the amp and the other four wires go from output of amp to the front speakers. Very easy and no loc hidden behind the radio

Originally Posted by Snoman

Your target box size for the Polk MM1240svc will be approximately 1.2-1.3.

Qtc Vb Fb F3
0.707 1.301 42.42 42.43
0.725 1.179 43.50 42.45
0.750 1.040 45.00 42.57

Basically, build or purchase a 1.1-1.2 ft^3 / speaker box, add 1 lb of poly fill, drop your speaker in and enjoy. Don't forget, all speakers require "burn in", generally 40 hrs, so be patient after you start up your system.

Ordered a mm1240d. Polk recommends a .88 cu/ft sealed as "ideal size" which is what I've got coming a cheap one off amazon for now. I'll build a better one when I get a chance. I got the dvc version, the mm1240d I've noticed some of the specs are different what do the calcs show for that sub?

[Snoman]

Originally Posted by fif_gen_powa

...
Ordered a mm1240d. Polk recommends a .88 cu/ft sealed as "ideal size" which is what I've got coming a cheap one off amazon for now. I'll build a better one when I get a chance. I got the dvc version, the mm1240d I've noticed some of the specs are different what do the calcs show for that sub?

"[Insert manufacture] recommends..."

^^^ This is and nearly always has been pure snake oil. Talk to a custom installer, people with experience or break out your own Thiel Small parameters and you will discover they are misleading you or flat out lying through their teeth. Unfortunately and depending on your particular viewpoint and respect for sound quality, there is a deep argument that states they are correct. Generally speaking, you'll need to decide for yourself. You haven't done "bad" with the off the shelf box and while the manufactures "recommendation" is not technically "wrong", this sub requires 1.3 cu ft before you will begin to see its maximum potential.


"dvc" subs by their very nature generally require more air and more power. I tend to shy away from them because in many cases, you can purchase two svc subs, build a slightly larger box and outperform the single dvc.

These are the tuning specs for the PA MM1240dvc;



Qtc Vb Fb F3
0.946 0.876 47.28 38.18 <--- your box. tuned @ 47hz, -3db usable @ 38hz
0.900 1.040 45.00 37.33 <--- Choice A
0.850 1.291 42.50 36.52 <--- Target. tuned @ 42.5hz with -3db usable @ 36.5hz
0.800 1.671 40.00 35.89 <--- Using a lower Qts than 0.85 produces negligible performance returns for this sub

Vb = net internal box size in cu ft
Fb = tuned box frequency
F3 = -3db frequency of box

[fif_gen_powa]

Originally Posted by Snoman

"[Insert manufacture] recommends..."

^^^ This is and nearly always has been pure snake oil. Talk to a custom installer, people with experience or break out your own Thiel Small parameters and you will discover they are misleading you or flat out lying through their teeth. Unfortunately and depending on your particular viewpoint and respect for sound quality, there is a deep argument that states they are correct. Generally speaking, you'll need to decide for yourself. You haven't done "bad" with the off the shelf box and while the manufactures "recommendation" is not technically "wrong", this sub requires 1.3 cu ft before you will begin to see its maximum potential.


"dvc" subs by their very nature generally require more air and more power. I tend to shy away from them because in many cases, you can purchase two svc subs, build a slightly larger box and outperform the single dvc.

These are the tuning specs for the PA MM1240dvc;



Qtc Vb Fb F3
0.946 0.876 47.28 38.18 <--- your box. tuned @ 47hz, -3db usable @ 38hz
0.900 1.040 45.00 37.33 <--- Choice A
0.850 1.291 42.50 36.52 <--- Target. tuned @ 42.5hz with -3db usable @ 36.5hz
0.800 1.671 40.00 35.89 <--- Using a lower Qts than 0.85 produces negligible performance returns for this sub

Vb = net internal box size in cu ft
Fb = tuned box frequency
F3 = -3db frequency of box

Ok so you opened my eyes to a lot, been playing with box building programs and putting in the specs for this sub and one on the diyma site is showing like 3+ cu/ft sealed boxes, whoa.

Didn't realize SVC and dvc can play that big of a roll in the same speaker. So looks like your min being 1.0 cu/ft and max 1.7 cu/ft with optimum size at 1.3 cu/ft. I just don't understand why they would recommend a size drastically smaller? I'm going to build another​ box when I get a chance curious to see the difference it makes.

Thank you snoman, good stuff as always. I'm not sure of any reputable shops in my area, Pompano Beach, Florida 33060 but if there are any I'd love to check them out

[Leo72793]

Originally Posted by fif_gen_powa

Ok so you opened my eyes to a lot, been playing with box building programs and putting in the specs for this sub and one on the diyma site is showing like 3+ cu/ft sealed boxes, whoa.

Didn't realize SVC and dvc can play that big of a roll in the same speaker. So looks like your min being 1.0 cu/ft and max 1.7 cu/ft with optimum size at 1.3 cu/ft. I just don't understand why they would recommend a size drastically smaller? I'm going to build another​ box when I get a chance curious to see the difference it makes.

Thank you snoman, good stuff as always. I'm not sure of any reputable shops in my area, Pompano Beach, Florida 33060 but if there are any I'd love to check them out

Sadly not too many good ones out there. im in jax fl and very few are decent. went to one and watched them CUT the factory plug and solder so they have to come back to their shop. I left sideways with smoke before they could damage my car

[Jazzzed]

Originally Posted by Snoman

I love the Kappas as absolutely nothing beats them on price except the subs, nothing. The Polk Audio MM series subs have higher SQ and better specs, albeit sealed. I've never been a fan of ported, only to point to the Rockford Fosgate P2s, but the P2s have lower specs across the board compared to these 120.9w. The kappas should do extremely nicely and the only sub better in that scenario is going to cost $500+ each easily.

I haven't been a fan of Sony/JVC/Pioneer (entry level) amplifiers since well, ever actually. I knew friends that bought them growing up and they immediately replaced them. My first amps I owned and installed were Alpine, Rockford Fosgate Punch and PPI (when they were still good). Manufactures at entry level leave out components or use cheaper quality to achieve these price levels that frankly, I could never justify. The list of potential problems are endless, lack of power, faulty power rails, fried components, potential line noise to name a few and I would rather purchase a quality amp the first time. If you need something and can't wait then I suppose it will have to do though at a minimum I would suggest a high quality 5-channel from alpine, JL, RF-Punch through ebay, craigslist, diyaudio.com, etc.

Off the shelf, the "lowest quality" single amplifier (5-channel) I'll recommend for our vehicle is the Alpine PDX-V9. There is absolutely nothing that comes close to the sound quality of Alpine, power availability for it's street price of $425. If you can find a nice one used, I would pay no more than $300 for it. Comparing amps in the used market is a grey area I simply don't enter as there are too many variables. Just make sure it's a quality amp, buy local or with a guarantee that it works and you should be fine.

Think of your amplifier as the engine powering your Saturn V Rocket, one simply doesn't install a tractor motor when you can have the Rocketdyne F-1 for relatively the same price.

I can appreciate this post since I too had Alpine and PPI back in the day. MB Quart too when they were still good. Alpine definately did have their own sound going all the way back to the cassette days. They also owned Luxman, and the Luxman home stereos had the Alpine sound as well. I still have one of those to this day and love it.

[Snoman]

Originally Posted by fif_gen_powa

Ok so you opened my eyes to a lot, been playing with box building programs and putting in the specs for this sub and one on the diyma site is showing like 3+ cu/ft sealed boxes, whoa.

Didn't realize SVC and dvc can play that big of a roll in the same speaker. So looks like your min being 1.0 cu/ft and max 1.7 cu/ft with optimum size at 1.3 cu/ft. I just don't understand why they would recommend a size drastically smaller? I'm going to build another​ box when I get a chance curious to see the difference it makes.

Thank you snoman, good stuff as always. I'm not sure of any reputable shops in my area, Pompano Beach, Florida 33060 but if there are any I'd love to check them out

The best way to describe the difference between SVC and DVC is to take two SVC speakers, then cut the cone out of one and melt the magnet into the other. It's like combining two SVC speakers into one, sorta, but this is a high level view of the result. It will handle more power and the physics will change requiring more air than a simple SVC, but it should tune slightly lower as well.

Manufactures recommend enclosure sizes to push sales, pure and simple. Vehicle trunk space is limited but if presented a pair of 12" to you and stated one requires 1.5cuft and the other requires 0.75 cuft (both from reputable names), which one would you lean towards?


Most of the quality shops in Florida are in the Tampa/Orlando area, however these two are in your neck of the woods;

Weir, Sage Sounds Good Stereo Miami, FL
Mangs, Tom Serious Autosport West Palm Beach, FL

[Snoman]

Originally Posted by Leo72793

Sadly not too many good ones out there. im in jax fl and very few are decent. went to one and watched them CUT the factory plug and solder so they have to come back to their shop. I left sideways with smoke before they could damage my car

Not defending their reasons or the exact scenario you witnessed, but soldering is in fact the most professional and respected method within our industry to splice into wires. Tapping and taping is proven to lead to oxidation which is 100% guaranteed to break down the splice within a few years causing complete rework. That is of course if simply doesn't fall apart from road vibration within 12 months like they normally do.

Originally Posted by Jazzzed

I can appreciate this post since I too had Alpine and PPI back in the day. MB Quart too when they were still good. Alpine definately did have their own sound going all the way back to the cassette days. They also owned Luxman, and the Luxman home stereos had the Alpine sound as well. I still have one of those to this day and love it.

[Sounds Good Stereo]

Thanks for the recommendation @Snoman.

We have always took the opposite approach to subwoofer packages. We first decide on these factors & then choose the best subwoofer to match.

- Space the customer is willing to take up
- Level of sound quality & tonality
- The amount of output while retaining above SQ
- Available budget for subwoofer package

Once we understand these, we then model several subwoofers to decide which will provide the best response in that airspace. Once we narrow down these options, we use our experience working with sound quality systems to decide which will provide us the best tonality.

I know this is a older post, but wanted to add this mindset to the post so others can get a better understanding when shopping for subwoofer systems.

If anyone has any additional questions, you can give us a call at the shop 305-576-4665. Also, if you want to see some cool cars, check out our car audio installation portfolio here

Originally Posted by Snoman

The best way to describe the difference between SVC and DVC is to take two SVC speakers, then cut the cone out of one and melt the magnet into the other. It's like combining two SVC speakers into one, sorta, but this is a high level view of the result. It will handle more power and the physics will change requiring more air than a simple SVC, but it should tune slightly lower as well.

Manufactures recommend enclosure sizes to push sales, pure and simple. Vehicle trunk space is limited but if presented a pair of 12" to you and stated one requires 1.5cuft and the other requires 0.75 cuft (both from reputable names), which one would you lean towards?


Most of the quality shops in Florida are in the Tampa/Orlando area, however these two are in your neck of the woods;

Weir, Sage Sounds Good Stereo Miami, FL
Mangs, Tom Serious Autosport West Palm Beach, FL

[Snoman]

Originally Posted by Sounds Good Stereo

Thanks for the recommendation @Snoman.