70 replies to this topic

[Ruckus]

I would ALWAYS go for control first then volume.

If you want SPL and do it right it will cost you.. both Space and Money.

[MGBailey007]

looking good mate

[freshairmini]

Thanks!

(null)

[freshairmini]

Little bIt of an unpdate. Spent a bit more time after work fiddling with the gains. Managed to get the sub (rear channel) gains set about right. Made the sub more noticeable and louder with out being overly loud and overpowering. Basically bass when bass is needed.

Had a little go on the front gains, but no luck. I set the HU volume at just over three quarters as I wouldn't go near that volume usually, so my maximum, and turned the gains slowly up. Apart from getting pretty sound I couldn't hear and distortion or clipping. Which is weird considering the speakers are rated at 80watts rms and 150watts peak, and the gains can go all the way up to 8volts (HU outputs 2volts max).

So... Who knows. I have seen these little mp3 player sized oscilloscope's on eBay which could help/make it a lot easier and more accurately set up, at around £40-£50 not sure whether it's worth doing.

But it's progress none the less!

[Ruckus]

Whats the amps output again ?

Edited by Ruckus, 07 March 2012 - 12:16 PM.

[freshairmini]

Whats the amps output again ?

100watts rms, if what PG says is correct. But from what I've read about PG they used to be good for there RMS figures. Whether my amp is one of the good ones Who knows.

[Brams96]

One thing I would say is good on you mate for making your own stuff! Be careful of those battery terminals though as you don't want a big positive terminal coming into contact with the body . . . spark, Boooom!

[freshairmini]

One thing I would say is good on you mate for making your own stuff! Be careful of those battery terminals though as you don't want a big positive terminal coming into contact with the body . . . spark, Boooom!

Indeed , I'll have them pointing inwards towards the battery so shouldn't be an problems!

Edited by freshairmini, 08 March 2012 - 10:08 AM.

[freshairmini]

Update:

After struggling with the gains for the front OZ speakers I thought I would try and find a cheap oscilloscope. You can get these £50 ones that I think are built into a cheap mp3 player case from china. They are supposed to be pretty good, if a little complicated to use, seen as the instructions are useless.

Also I wanted to see if I could get one cheaper... And I can at £17 (+£3 for delivery) its pretty cheap! It looks like this:


It has a maximum input voltage of 5volts which for a larger install wouldn't be enough. But for me its fine, and someone suggested building into my install somehow which could look quite cool!

So in a weeks time I should be able to test it out!

Edited by freshairmini, 08 March 2012 - 10:09 AM.

[Ruckus]

Link please.... me want ;)

[Ruckus]

Just a thought... 100watts RMS with a 4 ohm speaker is 20 Volts... i'm not sure this unit will be able to handle the voltage without going bang!



Voltage = square route (100W X 4 ohms)
Voltage = square route (400W*ohms)
Voltage = 20V


RMS power of the amplifiers output by the impedance of the Driver/s.
The square root of that figure = Voltage.

Edited by Ruckus, 08 March 2012 - 11:43 AM.

[freshairmini]

balls! really, I didn't think of that!

here's a link to it anyway: http://bit.ly/yDrOc7

I guess it would be OK for looking at where the HU clips, but not the amp?

[Ruckus]

balls! really, I didn't think of that!

here's a link to it anyway: http://bit.ly/yDrOc7

I guess it would be OK for looking at where the HU clips, but not the amp?

Yes it would be perfect, its funny that the guys on TA did not point this out?!

anyway to help with the amp/speaker set up do the following:

This is a copy paste, not my words as I don't have the time to write my own guide at the moment ;)

To set the gain(s), you need two things:
1. A DMM (digital multi-meter) that is capable of measuring AC voltage (needs to be able to measure up to a range of 200V).
2. A test tone CD to use to set the gains at the correct setting.
Now, to set the gain(s):

• 1. Start the vehicle, and pop the test tone CD in the head unit.
  2. DO NOT hook up the sub(s) or speaker(s) to the amplifier while doing this, just leave the outputs unused at this time.
  3. Now, time to set up the head unit.
• 
  
  a. If the loudest you listen to your music at on a regular basis is 22/35 with bass @ +3 and treble @ 0 with MX (or any other sound processor) on, use those settings. NEVER turn the headunit above 3/4 of the maximum volume.
  b. Remember to have the car turned on.
  c. If you want to use bass boost on a sub amp, set it prior to setting the gains on the amp and use the center frequency of the bass boost (45 Hz for most amps) as your test tone.
  d. Please remember that if you have a subwoofer volume control on the headunit and/or a bass knob for the amplifier, set it to the maximum before you set the gains on the sub amp.

4. Take the leads from the DMM and but them on the outputs from the amp.
5. Set the gain so that the outputs of the amplifier equal the voltage you found above**. This is a MUST.
**For 100 watts RMS at 4 Ohms you are looking for 20 volt AC

UnClipped = Correct Voltage of the output = square route(RMS Power X impedance of the speaker)

Edited by Ruckus, 08 March 2012 - 03:50 PM.

[freshairmini]

That helps alot, Thanks.

Just got to find out if the AC works on my MM as the DC has packed up last time I used it!

[freshairmini]

Bit of a disappointing update:

So I was hoping that I could show you a picture of my new acquisition for my car audio system, in the form of one of (hopefully) two genesis profile 2 amps. But the guy I bought it from off eBay thought it would be a good idea to send it in just two, yes two, layers of bubble wrap. He obviously thought that was OK for a sensitive piece of audio equipment. moron.

So I have one damaged genesis profile 2 amp. LAME!