Proposed Setup, tell me what you think

[winkychevelle 10+ year member]

Line driver question:
I have read that one use of a line driver is to boost signal thereby not making it necessary to increase the gains to the point of introducing additional noise. I am looking at miniDSP's which are reported to have low voltage output and so I am considering using a line driver if it will mean less distortion.

Assuming this is true, how is this possible? If a line driver boosts the voltage wouldn't that make it an amp? and wouldn't it introduce noise that would get amplified resulting in no net change?

It just seems that a line driver will also "drive" existing noise as well, introduce its own noise, and submit the final product for further amplification... thereby invalidating its implementation as a means to use less gain and get less noise. Or to say it differently its a pre-gain gain. Is not all gain created equal, or are line drivers a lesser of gain evils?

Thank you

line drivers are generally used to boost voltage on the long runs of the rcas this raise in voltage can block external electrical noise from entering through the un-shielded rcas. this rise in voltage also allows you to keep the gains down on the amp but this doesnt mean the amp wont have to work as hard to make the same wattage. most people think that lower gains mean lower distortion rates but this is dependent on matching the gain to the input voltage on the amp. this is were overhead comes in handy

say u have an amp that makes 1000w for an input voltage of 4v at 1%thd if you needed say 750w you might only need to give this amp 3v input and recieve .75%thd due to the amp only pushing 3/4 of its possible power this is all theoretic though. the only way to know 100% for sure is to test and test and test some more.

though boosting the rca voltage with in the range of the amps handling can rejest external noise which would be better for sq. hope this answers your question

 

[BnGRacing 10+ year member]

Using a line driver with the miniDSP is a bad-bad-bad idea.

Those things have problems accepting high voltage inputs and you may need to use one of those RCA level controls to lower the voltage so you don't clip the input side of the mini DSP.

Any THD figure you'll see will be "A-weighted". That's kind of a bogus way to fluff the specs as A-weighted figures are taken at very high frequencies and low power levels.

 

[musical_high 10+ year member]

@winkychevelle I think I understand. The signal to noise ratio would be greater with greater voltage since much of the noise will enter AFTER the line driver. The distortion from unshielded rca's will be less. Is a line driver an amp or does it boost voltage some other way? It seems that's all the line driver would be good for, reducing noise after the fact.

But do they reduce noise that is already present in the line driver inputs? (Not directly but through the process you explained) I understand that they don't actually reduce noise, but that is the net effect.

@BnGRacing I came across a review that claimed the power dropped by 4 db across the mini-dsp, and suggested use of a line-driver to drive the minidsp outputs so that less gain would be needed. However in his setup the minidsp was adjacent to his amp and unless the line driver was mounted right on the minidsp the length of cable running between the dsp and line driver would be equal to the length of cable between the dsp and his amp. Therefore still having the same length of, to simplify, "not line-driver shielded" cable. Weighing the merits of driving the outputs and if it need be done what some high quality line drivers might be?

Does the cea-2006 thing I see next to amps require manufacturers not to a-weight?

 

[winkychevelle 10+ year member]

@winkychevelle I think I understand. The signal to noise ratio would be greater with greater voltage since much of the noise will enter AFTER the line driver. The distortion from unshielded rca's will be less. Is a line driver an amp or does it boost voltage some other way? It seems that's all the line driver would be good for, reducing noise after the fact.
But do they reduce noise that is already present in the line driver inputs? (Not directly but through the process you explained) I understand that they don't actually reduce noise, but that is the net effect.

the line drive is an amp of sorts it does not normally add a perceptible amount of noise but it will to a very slight ex-stint add noise. the advantages of the line driver is when u raise the voltage, noise after the driver itself is rejected at a much higher rate than lower voltages. it causes the rca to reject interference from other electronics in the vehicle. and if your amp doesnt havethe range to pick upthe low voltage rca signal u can boost or cut the voltage to put it in range.

a line driver is normally not required in most any install and i would avoid one unless you start having problems with clipping the amp at higher gain levels. some amps do not like to be played with the gain wide open were as others dont like really low gain settings. this is dependent on the particular amp being used

 

[musical_high 10+ year member]

At this stage I am considering focal's polyglass 165 vrs x 4. They max at 60 rms, is this too low? I only need enough volume for happiness, also while my hearing is not extremely sensitive(no spidey senses) my pain threshold is low when it comes to sound. I put tissue in my ears at concerts or anywhere loudspeakers are speaking. I cover my ears for sirens... so.. The 165 vr's have good reviews.. no reviews on the vrs's.

If I know the speakers will kick *** I can adjust the rest of my project. Does anyone here run focal polyglass?

Are component wattages the sum of the tweets and midrange drivers rms wattage?

Thanks in advance

 

[musical_high 10+ year member]

Rethought things. Passive for now.

Gonna get focal polyglass x 4 component set.

JL HD 900/5 amp.

Used HU

Audio Control DQS for eq

Rethinking the sub. I want sq but I don't mind arrhythmias either. I'm just not sure what to get. heading out tomorrow to check out different subs.