Yes, its the lenght of each port. Two 3" ports are almost equal to one 4" port. If you tell winisd to use a 4" port you should get about the same lenght as with two 3" ports.

itchnertamatoa wrote:
Anyway, I asked Dereck to test the amps, and take all the blame for it
I knew (and still know) what I was getting into in doing so, and if it were to be done again, I'd do it again ...

Care to share the dyno results with us?

Your sub will sound much better too, if you run it at 8ohm bridged. Especially if its ported.
No need to touch the signal cables, just put the subs coils in series and that will sum L+R channels.

Good demonstration Eric! Gain setting is almost always too difficult to get just right without test gear. ajaye wrote about gain overlap. Some decks have this "built in". I use a Kenwood KDC 6051 which reaches maximum signal level at volume setting 33/35 so there is a risk of sending a cli...

PG amps are known for headroom yes. Weird thing is I have never seen the numbers. Trust me I have searched but all you see is RMS power measurements all over the place. This is so stupid because when playing music, dynamic power is what matters, not RMS.

One way a sub can end up seized is the motor structure becoming misaligned. Sometimes the glue holding the magnet and plates together is faulty so the motor gets knocked or vibrated out of alignment. You don't always notice this because the magnet holds everything tightly together.

When will we see the full review? Looking forward yo it

Why did you have the subsonic on and set to 55Hz? Thats just blocking your 55Hz test tone by several dB.

I dont mean CCA. CCA is much lighter than copper and you can see the aluminum colour at the cut end of the cable. This stuff I mentioned is probably some junk heavy metal with some copper for colour. Its a crime if you ask me to sell junk as power wire.

I have seen cables that look like copper and are heavy like copper but measure three times the resistance of copper. I don't know what they put into these cheap crap cables, but they can be dangerous because they can't take as much current as you assume.

ZX450 should do about 4x110W @4ohm

Here's a link to some amp power tests: http://amp-performance.de/487-Phoenix-Gold.html The numbers are very similar to what zeropoint quoted. But remember these are RMS power figures and in addition to being underrated PG amps have lots of headroom. If only someone tested dynamic power then PG amps ...

Link or it didn't happen. As far as I'm concerned a MS-275 does 275W rms bridged at 4ohm.

PG amps aren't class A amps either. Class AB with triple darlington is what they are. But for me too, it's the gold that sold me in the beginning. I think the first PG amps I ever laid my eyes on were the M-series. They have the beautiful combination of white and gold on the outside and the wonderfu...

It will be fine unless the weather (and car interior) gets very hot. I have an M50 running components and its installed under a false floor in the trunk. Theres no air circulation around the amp. Most of the year the weather is not hot here in Finland. In the summer on a hot day if I play the stereo...

Here's some measurements of lots of amps including PG. They haven't measured any ZPAs but you can find efficiency of some old PG amps:

http://amp-performance.de/106-von-Alpine-bis-Zapco.html

It will work fine. You will have to listen a little bit quieter than with the 1200.1 at full blast. About 4dB quieter. If you can manage that then go for it.

I know the ZPA 0.5 is legendary and all, but lets do the math. It has 50V rail caps so that limits the rail voltage and theoretical maximum power to about 1200W at 4ohms bridged.
I finally found pics of ZPA 0.5 guts without heatsinks and was wowed to find out it has 12 output drivers per channel!

When you send power to a speaker, that power turns 99% into heat. A sub can disspiate some heat through the cone, but most of it through the backside. Thats where all the cooling vents are. If the back is snugly wrapped in polyfill, then all that heat just builds up in the subs motor and basket. Pla...

Uhhhh, what? Are we having a spinal tap moment or what?

I think it is pretty straightforward that required port area is determined by power level. The figures I quoted are just a rough guideline some SPL guys have figured out in practise. If you build a box for two 10" or 12" or 15" or whatever size drivers which can only handle say 500W r...

One 6" aeroport is good up to about 2kW. If you plan on using all that Elite.1 power then use a pair of 6" or one 8" port.

SF302 and SF302A are rectifiers in the power supply section, not transistors.

Even if it makes same power at 1ohm & 4ohm there may be quite a noticeable difference in ouput. This may be actually just a sound quality issue. At 1 ohm the damping factor is just a quarter compared to 4ohm and the amp won't control the subs as well. This causes more boomy and muddy bass which ...

I figure its about 4kHz and the slope 12dB/oct. The actual slope depends on many variables unknown here so this is just a rough estimate. Component speakers usually have a crossover point around 3-5kHz with 12dB/oct slope so the xenon seems quite normal. Whats unusual is the RLC-circuit in the middl...