New generation Digital Amp + MB Quart ...Distortion

 

New member
Username: Saint_wrath

Post Number: 2
Registered: Mar-04
Hi, this is pretty frustrating. I'm a total newbi when it comes to car audio, and I just did a self install with a new JVC KD-AR8500, which as the new generation D-Amp 70wX4. Supposingly giving out sweet tight sound while archeiving 90% efficiency.

I used Cascade Audio VBlok VB-2HD for both front door(BTW, these sucker are thick, on japanese car dun try it, took me two days to do), install the speakers MB Quart PCE-216 at the front.

The back is a pair of cheap KENWOOD KFC-1679ie. NOW this is another mystery.....Now I got three sets of speakers for the rear when I was doing the install (the other two are coaxial Rockford T162C, and component Polk DB6500), and I compare them all right on spot with the head (use stinger 18G wire), guess what, the cheapest pair Kenwood win. The Rockford is so harsh mid and high, it has some metal feel. And looking at the cone material it is. The DB6500 has absolutely no midbass; mid yes, midbass no. For rear I just need super warm mid/midbass. The kenwood is acceptable until I find another pair of mid.

Now comes the Sherlock Holms question. I've been using them all for a month now (no sub yet, will install infinity Basslink...so the complete package would have NO amp visible at all). And even with the Head being 70RMS (advertised), Volumn at 60% already th eMAX the MB Quart can handle. I mean the adviced power range for them is 60-130. I'm driving it w/ Digital amp in the JVC head unit and it distort right at 60%. Okay the car is a 2 seater, so the Fade is like 75% to the front, but still, WTF, shouldn't it handle all the way. And the actual sound output is not that loud, just a hard-to-talk level.

If this doesn't improve I will have to sell this set and find another pair. But the thing is I've already search for so long to find this pair. With the tweeter inside, the sound stage is decent for a 2 seater already. It's just power level.

If some experts, especially someone has experience w/ this type of head unit. (Panasonic has one simliar, the top model), and MB Quart, please shy some light on this newbie.
 

New member
Username: Saint_wrath

Post Number: 3
Registered: Mar-04
BTW, The head unit is actually 70W max, 39 RMS. So I'm just baffled at the MB Quart's inability to handle the watt, w/ the doors fully dampened.

BTW, tested the rear kenwood as well, it distorts at the same vol. So how can a $200+ component distort at same vol as the $35 coaxial?
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 1966
Registered: May-05
it's late and i didn't really get the whole post. but if i understand the gist, you are underpowering your comps with your hu and clipping the signals. you will eventually damage them if you refuse to use an amp.
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 1967
Registered: May-05
give them as close to their rms as possible, if not an additional 50% for headroom.
 

New member
Username: Saint_wrath

Post Number: 4
Registered: Mar-04
Thank you....Yes I am a newbie, and an idiot. If I do the math, it'd make sense. The RMS is at around 60-70% of the speakers' recommanded level. So I can't really push it all the way.

Anyway, so now the question is, since I'm not gonna drive around pumpin out sound the next four lanes' cars can hear. Maybe just at 50% vol, at this there are no clipping, would I be safe in the long run for the speakers?

Because if I add an amp (myabe A JL 300:-)), I would just ebay this HU, since the only reason I get this unit is for the 4.1 channels time alighment and it's high power....I just dun wanna go through all the trouble.
 

Silver Member
Username: Tjmutlow

Post Number: 998
Registered: Sep-05
and a radio that is turned up that high is sending distorted power anyway.
 

New member
Username: Saint_wrath

Post Number: 5
Registered: Mar-04
There are not many review for the HU, and the digital amp (not MOSFET) it uses. But it should be pretty clean.

I know it's not running the speakers full potential, but the question is would I damage my speakers if I just run off the HU w/ 35-39 RMS at vol 40-50%, no clipping heard?

Just installed the infinity basslink today, it complement the sound well. But I have to use the EQ to tone the high 1 unit down to lessen the high.
 

Silver Member
Username: N2audio

Lawrence, Ks USA

Post Number: 293
Registered: Mar-04
you'd have to intentionally blast it cause any damage.

I doubt an HU rated at 39 rms (I saw no CEA2006 identification) could damage a decent 70w speaker even while being horribly clipped.

There are some small amps out there that can provide a good amount of power.

The older Blaupunkt PA series for example. Hard to find them anywhere other than ebay, but the pa275 is <7" x <6" x <2" and does 75x2 rms. The PA100 lists the same dimensions and is 100x2.
 

Silver Member
Username: Lbeckner

Tulsa, Ok Usa

Post Number: 470
Registered: Oct-04
I doubt that the head unit even puts out that much power. Get an amp.
 

Gold Member
Username: Mikechec9

Http://www.cardomain.c...

Post Number: 1980
Registered: May-05
no. there is no danger of damaging your drivers so long as you don't push them into distortion. the problem is your ears get more and more adjusted to the music.
most have a tendency to inch that vol up more and more to get the sound your after.
and then: *crackle* or *...*
but like opti said, so long as you don't push them to distortion, you're absolutely fine.
 

New member
Username: Saint_wrath

Post Number: 6
Registered: Mar-04
Thank you you all for giving this newbie a crash course. And yes I'm searching for an amp, Alphine MRV-F345(Saw reviews are good, plus SMALL SIZE), what do you guys think??? Does it eat lots of power?

I've been looking for and wondering about the Blaupunkt PA series, It looks good on paper, class D+A/B efficient, small. But what happened to it, why discontinued and no new model come out. If there are technical issue, it could be solved by now (Tripath got some spotlight in CES2006 w/ bunch of new products using their chips). If its no market, then why the new products(include highend HDTV w/ tripath, and new Texas Instrument(yes they make amp chipset this year)) using this technology. I mean I for one would use it.

The reason why I try to do without one is my car is a 1993 del sol, a light small two seater. And unless I relocate the battery(currently a Hawker PC680, a deep-cycle MOTOCYCLE Battery), I was afraid the small battery in it wouldn't hold (a 200w infinity basslink is already in there).


I mean I am a programmer, doing bits and bytes all days. And it's 2006 already, why can't we do full digital processing all the way to the speakers, including amp?! I know it's required to have all the headroom for the sound, but the heat coming from a bigass amp is not helping the gas mileage/electrical system, nor is it helping to maintain the true sound from the source. ($0.02)



The new Alpine PDX line looks incredible on paper. Does anyone knows what technology goes in the amp? There are shop producing digital amp chips, Tripath and Texas Instrument(new). What is in it that makes it so small and efficient.
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