sicilianoNYC

I have had this head unit for 2 months, and my old 9853 did this too. The problem is that the volume should go from 0-35, but mine stops actually getting louder around 24 or 25, from 25-35 there is no change when you try to turn it up. I have focal k2p components and a JL 300/2 amp, I set the gain on the amp to about 55-60%. I only want to turn the volume up a bit more, but I also dont want to turn the gain on the amp up anymore because this is not the correct way to tune the system. Help??

Paul350Z

iTrader: (1)

The only way to be sure of what's happening with your headend and amplifier's gain is with some test equipment.

Ideally you'd play a reference CD pink or white noise signal and use a volt meter to watch the amplitude of the signal going up and down. To check for clipping (which is WAY common in the systems that I have heard) you'd need to play back a test tone and then observe the amplifier's output on an oscillosope or use a microphone feeding a pre-amp and oscilloscope to again make a check that the sine waves are in fact sine waves with no clipping.

Depending on the design of your amplifier it may be already being driven to the limit prior to your volume control running out of rotation. Headends put out different peak volume voltages with 1V, 4 volts, and some above that being common. The amplifer has to be able to work with all of those common outputs and therefore the gain control built in to your amplifier.

I set my system up similar to a home theater where you take a test CD with pink noise recorded and adjust the volume control to some level - I used -3 dB - and then crank the gain up to match a volume level. I used the THX standard of 85 dB in the house and set the car for 100 dB (too loud!). Here I'm peaking in some frequencies at +105 dB before turning the system down further and adjusting the equalizer.



I then played back individual sine ways looking for clipping and distortion using an acoustic analyzer (TrueRTA.com) looking for any odd ordered hamonics which "spout" like weeds when the amplifiers/speakers aren't linear.

james840a

iTrader: (7)

Paul350z, Nice break out box, whats that for?

16psibrick

iTrader: (10)

paul, how about you take a drive up norcal or let me rent the rta for a week when i am done with my car?

Paul350Z

iTrader: (1)

That black box to the right of the laptop is a phantom power supply which sends 48 VDC to the lab microphone - it's a condenser type and needs a professional type power supply to get it running.

The TrueRTA software is only $99 for the 1/24th octave version, the microphone and power supply were less than $80 together and the Avia test signal disk is $40. Using the RTA software you can burn your own test CDs with a desktop computer (which I plan to do).

If you really want to see a neat toy Google a PAA3 - a personal audio assistant. The thing is the size of an iPod and has a little analyzer display built-in. Mucho cool.

sicilianoNYC

thanks for hijacking my thread boys!

james840a

iTrader: (7)

already got the PAA3

james840a

iTrader: (7)

As for me, i have been a alpine lover for many years now. I use to have the 9855 and didnt have any proplems. Paul350z is right on, check the gains on the amp. If your not sure on how to set the gains correctly to match the head you, you may want to take it to a proffetional audio shop that has an RTA and other equipment.

Paul350Z

iTrader: (1)

You're the one who got me to buy the TrueRTA program!

james840a

iTrader: (7)

true true, i think we both got great products

jdohman

iTrader: (1)

if the system does not get any louder it is because you do not have enough power or you should maybee look into sound dampining. Tuning up the gain will not work in your scenario. The system has allready reached its max

james840a

iTrader: (7)

Hows this going, any news?