Amplifier under seat? Audio advice needed

[jdoug]

I'm no audio expert but am trying to plan stereo install in 63 coupe.
I want to hide speakers as much as possible and I think my upholsterer can deal with most anything.

So, thinking something like this:

Retrosound head unit
Dual channel speaker that I can put in dash. has to be small. retrosound again?
If I could fit them then 2 small kick panel front speakers
4 channel amp that i would prefer not be visible - under passenger seat?
2 larger speakers for rear quarter panels.
hidden powered sub - under back seat?

A reasonable plan? Any feedback? Any suggestion on brands and models?

[O2COOLED]

[jdoug]

[craigolio1]

Hello!

Finally a thread I can contribute to as back in the day I was a car stereo installer.

If you want stealth, here is what I would do. Mount a head unit of your choice in the glove box using one of these:

https://www2.cip1.com/ProductDetails.asp?ProductCode=C13-3033

This way you get much more choice in what you can use. It can be controlled with Bluetooth or an IR remote if you like.




Mount the largest speakers you can in some prefab front kick panels like these:

http://www.jbugs.com/product/331-003-GHIA.html?Category_Code=vw-karmann-ghia-speakers-panels-trays

I'm pretty sure there are others too. I just found those quickly.





Put a 5 channel amp under the seat. Something Class D would be good as they generate less heat and have a smaller foot print. Something like this would work. It's about 9"W x 9"L x 2.5"H, is 40w RMS x 4 and 150w x 1 RMS for the sub, and has all of your built in cross overs:

http://alpine-usa.com/product/view/mrv-v500/



Using a self powered sub really limits you as far as flexibility, replacement/repairs, and complicates the wiring as it has to be treated like you have two separate amps. For the sub, build a custom enclosure for a woofer that requires a small enclosure and put it behind the back seat. I don't know your taste but a single 10" or 12" would be good for most. you may only be able to fit a 10" back there. Something like this would work. :

http://www.jlaudio.ca/10w0v3-4-car-audio-w0v3-subwoofer-drivers-92165

The 10" only requires .65 cuft which is very small and can be fit into small spaces



For speakers I would forget about using the dash location. That speaker from Retrosound only handles 25w which is not much at all. Your system will be limited to the weakest link which in this case, would be that speaker. You'll try to turn it up so you can hear it with the window down and all you'll hear is it bottoming out.

If you are using a sub then there is no reason to make the back speakers larger. The sub will make up for any bass/mid-bass you need. By matching your 4 speakers you ensure they all perform equally. If you put say, 4" in the kicks, and 6" in the rear, your system would be held back by the 4", same as it would with the smaller dash speaker. That's very much an over generalization as a lot can be tweaked by changing cross over points etc, but its still best to match them if you can. For added stealth, ditch the trashy looking speaker grills and replace them with plainer looking ones painted to match the carpet, or cover them in speaker grill fabric for a classy custom/stock look/

Kick panels are a great place to put speakers. The sound travels the farthest distance before reaching your ears so you get a fully developed sound and better imaging (the sense of separate left and right, another reason to not use the single speaker in the dash - it produces both channels but coming from the same spot so you don't really hear it AS two channels).

You could fit 6" in the kicks and the rear quarters and they can play low enough to transition nicely the sub. With the cross over set just right they will sing!

Just some food for thought. My advise is just my personal opinion. YMMV.

When it comes time to wire it up fell free to PM me if you need advice.

Craig

edit:

For some good inspiration check out Car Stereo Review from Jan/Feb 1997.

http://www.caraudiojunkies.com/showthread.php?1369-Frederick-Collazo-1974-VW-Karmann-Ghia-1997-CSR

It was very tastefully done and except for the head unit, is very stealthy. Pay particular attention to the kick panels and the two 10" JLs behind the back seat. It's a convertible. You have much more room!
_________________
I'm the new guy. Thanks for your patience.
1970 Ghia Convertable - Restoration in progress.

Link to my build thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=637602

Located in the Toronto area.

[jdoug]

Awesome! Exactly the kind of information I am looking for.

I think I still want to use the retrosound head. Don't want to deal with glovebox.

Do speakers and amps come with mounting hardware? What is best way to mount the speakers? Do you need enclosures?

I'm need to do this now. I'm doing body off resto. Body is painted and I'm just about finished rewiring it before I put it back on chassis and then it's off to upholstery shop.

If you're into it please give me some recommendations via PM or here. For example components I could get on Amazon.

P.S. My car didn't come with a radio so I have no antenna and don't really want to add one. Do these hidden ones work and where would I mount it?
Thanks!

[craigolio1]

I'm happy to help.

If you're getting the Retrosound radio, then be sure to get one of the models that has the subwoofer outputs. I couldn't find it on their site but usually if a head unit has a separate subwoofer out, then it also has a subwoofer volume which really helps tune the sound nicely, as you can increase just the sub, vs. the bass to every speaker which can cause distortion in smaller speakers.

Speakers and amps don't usually come with much. Speakers may come with some cheapy wire but it's not worth using. Get some 16awg or 14 awg oxygen free speaker wire, brand is irrelevant in my opinion, to wire your speakers.

Amps don't come with anything either. You'll need a power wire, ground wire, fuse at the battery and a turn on lead to run to the head unit. The power and ground gauge is determined by the current draw and the length of the run but you should be fine with a 10awg. The fuse at the battery is to protect the wire and so it can be larger than that on the amp but to be safe you usually just make it slightly larger than the amp. You'll also need three sets of RCA cables to go from the head unit to the amp. Twisted pair are the best but they are more expensive.

To prevent possible ground loops, the head unit should share the same power and ground as the amplifier. The constant power fed from the battery to the amp is used to power the radio and then the IGN 12v+ is used with a relay to trigger this power and turn the radio on and off with the key.

All grounds should be to one central point like a seat belt bolt or even right back to the battery. A good option for us considering the battery may be very close if it's under the back seat.

I know VWs came with a generator. I believe to properly feed an audio system you should likely upgrade that to an alternator but maybe someone here can confirm that. I'm not sure. With a small system and only one amp, you wouldn't need a high output alternator.

The subwoofer needs an enclosure and the specs are in the box or on line. The enclosure should be built for the specific woofer. There are lots of free programs on line to design enclosures.

The other speakers are usually a "infinite baffle", or "free air" design which means they use the volume of the door, or what ever, as the enclosure. The key here is to make sure that the back of the speaker is completely isolated from the front so that the rear wave doesn't meet the front wave and cancel each other out, taking away all of your low end. In the case of kick panels, you would make a fiber glass and MDF back for the prefab kick to attach to , thus creating that separation. Fiber glass and ABS plastic are notoriously thin and they vibrate reducing your sound quality. To combat this you need to add mass to the baffle (what the speaker is attached to), and the enclosure. This can be done by packing the corners and inside surfaces with clay, or using multiple layers of sound deadening material like Dynomat (you can a cheap substitute in the form of water proof asphalt roofing membrane in 50ft rolls at the hardware store, enough for your whole car). For the kick panels, because you have essentially created a small enclosure, you can pack the cavity behind the speaker with quilting or some such fill. Heavy fill tricks the speaker into thinking the enclosure is much larger thus restoring the "infinite baffle".

For the antenna, you can run a long wire, about 30" long out of the back and tuck it under your carpet. You'll get decent FM but likely crap AM. You would get better reception on both if you use a proper antenna out side the car because the body of the car acts like a shield. We have the benefit of the engine being at the other end of the car, reduces interference.

As far as recommending equipment, i have been out of touch with the car audio game for a while and I'm not up on whats good these days. 20 years ago we were all about Soundstream, Precision Power, HiFonics, Rockford Fosgate, Phoenix Gold, etc. I presume they are still power players in car audio but what to buy is a mystery to me unfortunately. You should check out a car audio forum. One I used to frequent is DIY Mobile Audio. You'll get lots of recommendations there.

When your ready to wire let me know and I can email a wiring diagram to follow. Just know that if not done properly you can damage your gear, your car, or worse, burn your vehicle to the ground. If this stuff is foreign to you, you should bring in a pro.

Craig
_________________
I'm the new guy. Thanks for your patience.
1970 Ghia Convertable - Restoration in progress.

Link to my build thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=637602

Located in the Toronto area.

[SirNickity]

I'm from the old school as well. I still have a couple Precision Power and Phoenix Gold amps hanging around. That brings back memories.

Unfortunately PPI has changed hands a few times and no longer quite the example of engineering prowess they used to be, or so I'm told.

TBH, these days, everything is a switch mode supply followed by a PWM driver into an inductor, using the same chipsets designed by Tripath or Texas Instruments or whatever, so it's not like the Class AB days where you had these finely tuned linear amplifiers using proprietary tricks to optimize for low crossover distortion or lower noise or higher power handling, etc. In less egghead speak, it doesn't matter so much anymore. An off-the-shelf Pioneer or similar will do just fine.

I would hesitate to go under the seat because there's not much room there. Try to avoid mounting anything to the pan. Moisture flows along the pans when the rain leaks in or your shoes are wet. The rear seat/bench is a decent spot, as you can mount an amp to the underside and it will hover over the pan on either side of the tunnel.

In a coupe, there's some room behind the rear seat for a sub enclosure. In a convertible, you don't have quite as much space to work with. In this case, Parts Express carries raw drivers from Tang Band that I'm fond of. I have a few of the 6 1/2" neodymium subs - one in a tapped horn I use for my office computer speakers, and another test box I made, which is about 0.6ft3 ported, tuned to about 30Hz. It's not particularly loud but the depth is incredible.

For grins, I tested the ported box in my Ghia with a portable 40W Class D amp. It sounded nice, with useable extension to around 28Hz, but it wouldn't compete with highway noise. Instead, I'm planning a box for my vert that will use 2 of the TB 8" neo subs in slightly larger volume, tuned to 24Hz. It will -just- fit in the area behind the rear glass when the top is down, about 36x10x8 with a bit of an outward slope toward the bottom. I'll have to get creative with the port location - a pair of rectangular channels about 34" long with 4x1.5 area IIRC. I'm toying with the idea of rolling my own amp since I'll have an electric motor with its own 120VDC supply to tap into. Should be fun! ^_^

Sorry, I get carried away sometimes.
_________________
1970 KG Coupe
1974 KG Convertible (EV conversion underway)

[craigolio1]

I love the old school amps. I just sold my collection of HiFonics Series VII amps last summer so I could buy carbon fibre wheels for my tri bike.

When it comes time in my Ghia, I'll likely go old school again. Maybe some nice PPI Art Series , or Phoenix Gold M series amps. Those are two that I've admired but as of yet have not owned. My vision of my dream Ghia had a McIntosh MC4000M in the trunk to run everything but at 48". Wide I don't even know if it would fit in the trunk!

Craig
_________________
I'm the new guy. Thanks for your patience.
1970 Ghia Convertable - Restoration in progress.

Link to my build thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=637602

Located in the Toronto area.

[FRNKNSTNGHIA]

A lot of very good information has been provided in this thread. I am not a car stereo installer but have installed a few car audio systems in previous vehicles I have owned.

I am completely restoring a 70 Ghia Coupe and wanted something that I could enjoy on long drives but keep overall car audio budget to less than $500 total.

As my car is not going to be an original restoration but more of a resto-mod, I am running a custom fiberglass dash from Glass Action. I will not be running a head unit of any kind.

I will be using a Power Acoustik PWM-70 7-Band Equalizer that will send signal to a MB Quart Reference Series RA400.2 100W RMS x 2 channel amp. This amp will feed its power to MB Quart Premium PVM216 6.5" Components. All wiring will be oxygen-free copper wiring. Signal will be from my Iphone to RCA input. Components will mounted in prefab kick panels. The majority of vehicle will be lined with Sound deadening material.

The components are rated for 75w RMS and 150w Peak, so this will allow me to run the amp at less gain and still have plenty of power to push these speakers to the limit.

Most of these items are discontinued and hard to find, but I found them all new in the box at great prices.

[craigolio1]

That sounds like it'll be nice. It's distortion that blows speakers more often than over powering them. As long as your signal is clean (high res tracks on your phone, gains set appropriately - low like you say is even better!) and you set a high pass cross over to cut all of the bass out that your speakers can't play anyway, (maybe 60hz? You'll have to experiment)you should be fine. If your amp doesn't have a high pass filter that goes that low I can help you out. I have an Audio Control HPX that I don't need. You can program the cross over to any frequency you want with resistors. It has an RCA and a 3.5mm headphone input, and speaker level inputs if you want to connect your factory radio (if it's in the car). It is perfect for your application and much higher quality than your EQ. If that could help you out PM me. Maybe we could trade something.

I love MB Quart. Have had several sets.

Craig
_________________
I'm the new guy. Thanks for your patience.
1970 Ghia Convertable - Restoration in progress.

Link to my build thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=637602

Located in the Toronto area.

[craigolio1]

[SoCalJes]

Have you considered if you have enough in your alternator to push what ever you have + a 4 channel amplifier and the additional one in the woofer?
_________________
Jesse
71 Ghia
______________________________________
Just because it didn't come that way, doesn't mean it shouldn't have.

[craigolio1]

Indeed that is a good question. That Alpine amp I linked to for example has 60A of fusing so in theory, it could draw up to that amount. In reality it never will, except maybe in a split second burst during a perfect storm where every channel is maxed out, but still. This is important to consider.

Perhaps others can chime in with VW alternator experience.

Craig
_________________
I'm the new guy. Thanks for your patience.
1970 Ghia Convertable - Restoration in progress.

Link to my build thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=637602

Located in the Toronto area.

[swavananda]

I found the stock 55 amp alternator to be fine from my experience. A generator ,not so much. I run 2 amps, 4- 3way componet speakers and a 10'' sub.All Eclipse brand, about 15 years of use(Deck is newer) I forget the total watts of the set up,.I don't run it crazy loud but plenty enjoyable with top down on the highway. I also use a deep cycle optima battery. Lights do not fluctuate at all with bass hits.

Having a amp under the seats in a Vw sound like trouble to me.

[SirNickity]

[craigolio1]

Well there you go. I stand corrected. Thanks for joining in and clearing that up. Correct knowledge is always preferred.

What's your take on too much power vs too little? I've experienced that people are going to attempt to achieve the volume they want whether the power is there to do it or not.

Craig
_________________
I'm the new guy. Thanks for your patience.
1970 Ghia Convertable - Restoration in progress.

Link to my build thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=637602

Located in the Toronto area.

[TMI Products]

I just finished piecing components together for my other car which is similar to my T3 install. I didn't want to use a radio since I use my phone for Pandora or stored music, so I used a iSimple Bluetooth receiver into a Powerbass 9 band EQ to a Powerbass mini 5 channel amp. For the speakers I used Phoenix Gold components in the kick panels and 2 shallow mount 10s in a sealed enclosure with about 1.2 cu ft. (each sub needs about .4 cut ft). I worked for AAMP for about 9 years (which owns iSimple and PG as well as 9 other brands) so I knew the products and what was good and not so good. The amp, a friend worked at Powerbass and verified it was good quality. The small size will fit under a seat and its very efficient yet pushes the 3 10"s with ease. It has a low current draw so its not killing my 55A alternator. no rear speakers yet and I don't really have a need for them.

_________________
Mario De Leon
1965 Turbo Mustang Fastback
1966 Type 3 Fastback
VW Division Sales Manager
[email protected]

TMI Products
1493 Bentley Dr.
Corona Ca, 92879
1-800-624-7960
951-272-1584 FAX

[SoCalJes]

[SirNickity]

I'm not sure I see the difference. Distortion generated anywhere within the signal chain (to include the source material) has the same net effect, provided the amplifier reproduces the distortion.

That bit about holding the cone at a DC voltage has been circulated for a long time, but think about that as well: If your amp COULD have produced those peaks, the voltage wouldn't have stayed at DC, it would have kept going UP (or down, if it's in a negative swing.) How would a VC held at 22VDC heat up more than one that kept climbing to 26VPk? Doesn't make sense.

You could say it's because the VC isn't moving - no airflow. But that doesn't really make sense either. Clipping is only going to produce DC for very short periods. 1ms or less. The cone has inertia so it won't stop moving instantly anyway - no speaker can actually produce a square wave intact. By the time it settles, the lost transient has passed and you're on the descent again.

For there to be significant time in DC, the distortion would have to be extreme to the point the music was no longer discernible. It sounds plausible at first because applying DC to a VC (like connecting a car battery to the terminals) can quickly destroy a speaker - but again, it's just heat that does it. You're pushing 12.5VDC through 4 ohms (more like 3.2 ohms DCR) at 100% duty cycle. That's about 50W with no air circulation and no rest period. You've created a light bulb that no one will see. OTOH, hold an AA batt to a good subwoofer and it'll hold the cone at 1.5V until the battery dies. Not a problem.

I like to size my amp so it hits the rail voltage exactly at xmax of the driver. If the rails can't produce voltage beyond the lowest xmax frequency in the passband, you will not destroy the driver physically. (This is VITAL for bandpass and horn designs where the driver's cries of anguish will be filtered acoustically.) Likewise, many good drivers tend to reach thermal max at around the same power as xmax - otherwise what's the point? Something was over-engineered. In that case, a right-sized amp can do no harm to the driver.

The 10-20% headroom thing sounds like it originated by amp salesmen. Now you CAN thermally overdrive a speaker for a short time, since it has thermal mass and will not fail instantly, but repeated over excursion is bad. So I think if you need that +20% power, you should probably have bought a +20% driver to go with it.
_________________
1970 KG Coupe
1974 KG Convertible (EV conversion underway)

[bluedot]

I have a nice install that rocks - and I'm pretty picky cuz I produce music.

NO HEAD UNIT. Why when we do everything digital now thru an iPod?

iPod to Amp, directly. iPod in glovebox. Bluetooth control for the ipod via remote with magnet on the back to stick to dash.

That's plugged into a 2 way crossover. To the front speakers, and the sub in the back.

Sound Ordinance amp to run the front 2 way Morels in fiberglass kick panels.

8" Bazooka in the luggage compartment.