Crazy Eddie

Andy
Not to burst your bubble but any head unit that has an amp in is usually low end ...
The THD is extremely high in an amp powered head units.
If you want clean undistorted power then you need to go to a pre amp out head unit
I am confused as to what you are planning ?
Are you discarding the rear panels altogether ?
regards
Ed
ps using 10 speakers is not the answer
The answer lies in the correct placement and the correct selection of speakers
matched to the very low THD amp ... When they advertise the head unit putting
out 45 watts .. then take a look at the THD at the RMS level ...
The key to a great amp is not the output, but at a given high output the music is clean and not distorted i.e. ( very low THD )

Robby

Andrew- did you look at Walt Spectors site- the link I posted? First, that factory M490 rear speaker you're showing- that's exactly what I was talking about- the little piece that covers PART of the old 4X6 hole- the rest of the 6.5 fits into the 4X6- you need to see how they shaped it in the later cars- why are you trying to mount the factory speakers anyway? Not that they are bad, but, if you ever get decent power, you will have to upgrade them. BTW- NO HU is decent power- the rated 50w/ch of good HU's is WEAK compared to the rated 50w of most amps. The RMS is what you need to be looking at anyway, & I'm sure that is what Jaak meant by O.P.(?).

Also- Eddie is correct too- btw- Eddie- what was it that you used to seal up your front plastic adapter plates with to make it sound better? I'm about to go back to using those w/5.25 components instead of the 6X8's & would like to do that.... Also, I think Andrew is replacing the old panels w/the new ones- not removing them completely...


Andrew- those panels look the same as later 951 panels- will they definately fit into the window though? I know 968's had dif windows... Last- I'm about to e-mail you a few pics showing the rear area from a Turbo S, etc....

Crazy Eddie

Also- Eddie is correct too- btw- Eddie- what was it that you used to seal up your front plastic adapter plates with to make it sound better?
Bondo

I'm about to go back to using those w/5.25 components instead of the 6X8's & would like to do that.... Also, I think Andrew is replacing the old panels w/the new ones- not removing them completely...
More confused now
regards
Ed

Robby

Eddie- Andrew has a non-turbo S w/the early 4x6 speakers in the rear- the panels that covered these were normally the type that just has the holes punched in them instead of a speaker grill. Now that he has the panels off completely, he has bought some 968 ones I believe- not sure if they are the same ones he pictured, BUT, he mentioned having 968 ones early in this post. There doesn't appear to be any dif b/t them & 951 w/M490 panels though, but, I can't tell just from pics... anyway, he does not plan to discard the panels completely- he's just trying to update the look of the car, while doing this upgrade, by adding newer panels I beleive...


As far as me going to 5.25's instead of 6X8's- that is a completely seperate matter entirely... That is why I wanted to know what you were using (Bondo) to seal the plastic adapter frames- b/c I'll be using those again, only w/aftermarket 5.25's instead of factory...

Does that clear things up? :-)

Crazy Eddie

Those panels look just like mine ... 88 TS, that's why I am confused
I don't know how different they look than the 968 ones do.

As far as me going to 5.25's instead of 6X8's- that is a completely seperate matter entirely... That is why I wanted to know what you were using (Bondo) to seal the plastic adapter frames- b/c I'll be using those again, only w/aftermarket 5.25's instead of factory...
When you say, seal it up, you mean fill in the hollow plastic to prevent them from vibrating. Like I explained to you and Andy. Correct ?

Jaak Lepson

Robby ... I don't have a spec sheet in front of me so I am going by IIRC. I believe it is the RMS power ... usually the lower wattage power (O/P = Out Put) that is constant. Most units rate themselves on Peak Power and not the minimum power O/P.

A good unit will provide a constant 25 Watts O/P with a peak of about 60 to 70 Watts. If you picked up the HU's and felt the weight, the higher O/P current unit will be heavier.

As for speakers, I look for the highest output in db at 1 watt according to the specs. Most people do not run their HU at max unless they want to fry their units. If the value is lower, you need a high current amp to drive them. JVC is one that requires a high current O/P.

Crazy Eddie

Hey Jaak and all
I did a search and this is an interesting article I found
regards
Ed

Almost every manufacturer, distributor, advertiser in the world involved in selling domestic audio equipment - and more than a few hi-fi magazines! - uses the term 'watts RMS' (incorrectly, as explained above). How did this go wrong?

What happened is that they started to use it as a short hand method of saying that the amplifier's output conformed with a now-defunct US amplifier standard known as IHF A202, which was introduced in 1978.

The idea was that the words 'watts RMS' would serve to show the continuous average power output of an amplifier had been measured correctly according to IHF A202. That is, using the correct test signal (a sine wave), the correct period of time for measurement (more than five minutes), a properly calibrated, true RMS-reading voltmeter with an accuracy of better than 1% of reading, without exceeding a specific level of distortion (0.1%) into a defined load (usually 8-ohms) with the amplifier first having been pre-conditioned by means of driving all channels simultaneously with a 1kHz sinusoidal signal to a nominal power output into the rated load equal to 33% of the rated power output for at least hour (or more if protective circuitry interfered with continuous operation).

This was misguided thinking even at the time, and it's now time to fix it!
Ruminations by Stephen Dawson
I agree entirely with the argument that RMS watts is meaningless. In fact, we use that term as an extreme shorthand for power in watts calculated from measuring the RMS voltage (RMS is validly used in this context).

Having said that, I strongly support continuing to measure and report upon 'average sine wave output power', where 'average' replaces RMS as the shorthand, measured in the traditional 'resistive load' way, despite its shortcomings in the real world.

My reason? It is a proxy measure of quality. It does not always track precisely with overall quality of course (what measure does?) But it still gives important information. For example, compare a Marantz 100 watt home theatre receiver with a Harman Kardon one. The Marantz will deliver something like 5 x 80 watts average sine wave ouput power, whereas the H/K will deliver somewhat more than 5 x 100 watts, because H/K's policy for specifications is to report with all five channels driven, whereas Marantz reports for two channels driven. In real world performance terms, this matters not at all on the face of it. But it does indicate that the H/K has a beefier power supply.

In a sense, using power measurements is a bit like reporting on how much an amplifier weighs. Weight has no direct influence on quality, but a high weight does tend to suggest more attention has been paid to quality issues. And, likewise, with power output.

Robby

Jaak- that's what I meant- for ex- my Kenwood HU is 22w RMS & 47w peak, per channel. The gneral rule seems to be t hat RMS is close to half the Peak wattage for HU's & amps- speakers seem to be a little less, like RMS is ~1/3 peak. The new Alpine units are 60w peak & they don't advertise their RMS- it's really ~27 IIRC. Some Blaupunkts are 25w RMS & only have 45w peak, so, they have more than half... Not sure how this works... I usually go by RMS- actually, I factor both into it, but, am more concerned w/RMS- I've always read it as an average, sustained, continuous wattage... not sure how to apply what Ed just wrote about it... In any event, it seems to me that as long as your comparing apples to apples, then, you'll get somewhat consistent comparisons...

Ed- yes, that is exactly what I was asking about for the bondo- wanting to seal up the empty spaces in the plastic like you had told me before...

Thanks....

Robby

Ed- also- those panels shown ARE 968's I think & yes, they DO look like the Turbo S- I'm pretty sure they were the same, although later 968 rear speakers were a lot different- they have some sort of amp connected to them- someone sent me a pic- could have been you...? Anyway, they also had a smaller mid speaker up at the front of the door where the original 4x6 had been mounted- the early 968 M490s, as well as the Turbo S M490's, had a 3.25" in front of the 5.25, that was in the same plastic adapter & all mounted under the armrest- the later ones had an oval shaped speaker- it had no 3.25" in front of the 5.25. the oval was 4x6, but, I'm almost POSITIVE it is a round 3.25 or 3.5 speaker- it's just mounted in a 4x6 frame to mount in thetraditional metal 4x6 hole that still existed in our cars & 968's, etc (although covered by the solid door panels)... Then, they made a small round grill to let the sound through. This later 968 M490 was by far the best- it had two amps & each one ran certain speakers- the 6.5's had their little amps or pre-amps, or whatever- that thing must have been a wiring nightmare w/the standard dual connectors for each positive AND negative- then, w/3-way front X-overs, etc... I'd HATE to try to figure one of those thingg out. Why Porsche did this is beyond reasonable- it goes hand in hand w/having a fu**ing electric SR that has to be manually pulled out, where the ONLY electrical part is to raise the back of it ~2.5"- this actually cut down on the total amount it could be raise- manuals can be raased higher- not to mention, they are ~4lbs lighter, plus, they lose the electrical stuff, motor, gear boxes, etc... Anyway, to make it electric was bad enough, but, to make it such a ridiculously technical thing was stupid- multiple micro-switches, etc... With all that, you'd THINK they'd give us an inside handle to pull the doors closed with, but, I guess they have to go to Japan to figure out how to do that, huh....?

NZ951

Ed,

Bubble not burst, I always planned on getting an amp. I have got the 968 rear panels and they will be installed.

The final config will be something like:

6.5 in the rear
4 x 6 in the front (fockford's and kenwood's in car now, I will put in the best set in the front)
5.25 in the under armrest panel
1" flush mount tweeters in front panel (in car now)
8" sub in the rear cubby

Plus an amp to power most of them, what amp, I dot know yet.

Robby

Andrew- do you have 968 front panels too? also- you said you planned to run most of these speakers w/an amp- obviously, you'll have to run the sub w/an amp- I guess you decided to just go the sub route instead of running larger rears, like 6x8's or 6x9's....? Anyway, you'll want to run the rear 6.5's w/an amp. Then, all that are left are the 5.25 seperates & the the 4x6's. IF you ran a 3-ch amp for the first two + sub, then, a 4-ch amp for the last 4, you would be set, OR, could get a 5-ch amp & run all but the 4x6. would you run the 4x6's off the HU while the other's are run off amp(s)? I've always wondered how that would work. I've considered doing what you're doing & adding something in the factory holes up front in my Turbo S- like running some extra 4x6's or 5.25's, or, even a small set of 4" rounds or something & powering them from the HU- THAT is why I would like to know if I could BRIDGE hte HU- some say yes, olthers say no- IF so, I would actually consider running the 5.25's I'm about to put up there w/the HU & then bridge the amp for the rear 6.5's, since, mine is a small amp... anyway, too many possibilities- just wondering if you had thought any of that out....?

Robby

Does anyone know if the 4-ch of a HU can be bridged? Sort of like an amp, but, so that one could run one pair of speakers off all 4 HU channels & then run another pair of speakers off an amp???

NZ951

I have the front under arm rest panels... thats it, and cut a hole for the tweeter above the switches.

As far as config go, I was thinking 6.5 ad 5.25 and 8" 5ch all off an amp, and the rest off the HU. Thats the plan for now...

NZ951

Update:

I just bought some Infiniti 6.5 reference speakers. They have a higher nominal rating that the Kappas (90W) and will be able to mont the tweeter in as well if it sounds ok. The hertz is around 50. So not amazingly low, but till be a good low to mid range.

Robby

That sounds goot to me on the configurations- tell me how it works- I've thought about a lot of things like that...

The 6.5 Kappa coaxes I have are 70 or 75w RMS & they go down to 44Hz I believe- I know it's at least 45Hz.... Not sure that matters 100% though b/c a lot of gurus have told me that those #'s are sometimes off by small margins...

Are your 6.5's coax or components? You said that about maybe mounting tweeters, so, I was wondering...


How did you get the 968 pockets? I assme you meant the whole pocket- all the way from back to front- did you get the plastic speaker adapter frames for them as well? Those pockets w/grills are usually ~$300ea here....- they are pricey- I got my 968 panels w/pockets & grills, speakers, all panel hardware w/inner handles, etc, for $400 total, used.... was happy w/that.....

Where did you find the rear pockets w/speakers for $100 also? Those were new weren't they? They look nice....