pretty interesting results from a thorough bench test of my pioneer 7800:

[frankiebones 10+ year member]

i used two test tones, both at 0dB, one 50 Hz, the other 60 Hz. i did 2 trials for each, one with the HPF set at 80Hz, and the other with the HPF set to pass through since i didnt feel like putting the DMM to the subwoofer output since the RCAs are tucked deep in the trunk. with the HFP on the front output turned off, the preamp voltage readings i got from the front output will be identical to those i wouldve gotten from the subwoofer output.

the specs for my HU claim to be 5V preamp outs. i called pioneer and asked a tech support guy to inform me of which volume level the cleanest ouput signal could be achieved. he did not know, but he did tell me that the max unclipped output is 5V, and that anything under 5V should be clean.

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i got the following voltage readings with all the processing I use turned on, including my EQ settings and BBE levels (i'm only providing the relevant ones, i.e., the ones up to and including the clipped output levels).

PLEASE TAKE A LOOK AT THIS GRAPH!! it took a long time to make:

http://i39.photobucket.com/albums/e164/fcelau1/graphofpreampvoltages.jpg

50 Hz / HPF On:

vol. / voltage

37- 0.395

38- 0.443

39- 0.497

40- 0.557

41- 0.625

42- 0.701

43- 0.7865

44- 0.881

45- 0.988

46- 1.107

47- 1.241

48- 1.391

49- 1.56

50- 1.75

51- 1.962

52- 2.2

53- 2.47

54- 2.76

55- 3.16

56- 3.475

57- 3.9

58- 4.37

59- 4.88

60- 5.24

61- 5.73

62- 6.08

50 Hz / HPF Off:

37- 1.049

38- 1.177

39- 1.32

40- 1.481

41- 1.661

42- 1.8635

43- 2.1

44- 2.345

45- 2.63

46- 2.95

47- 3.3

48- 3.7

49- 4.15

50- 4.65

51- 5.09

60 Hz / HPF On

37- 0.431

38- 0.483

39- 0.542

40- 0.6085

41- 0.682

42- 0.765

43- 0.857

44- 0.96

45- 1.077

46- 1.207

47- 1.351

48- 1.515

49- 1.698

50- 1.905

51- 2.14

52- 2.4

53- 2.68

54- 3

55- 3.37

56- 3.78

57- 4.24

58- 4.75

59- 5.17

60 Hz / HPF Off

43 1.76

44 1.982

45 2.22

46 2.48

47 2.79

48 3.12

49 3.51

50 3.94

51 4.41

52 4.92

53 5.28

These measurements were all taken using 50 and 60 Hz test tones. After I took these measurements, I put in the "Explosive Car Tuning CD #9", which is recorded very close to 0dB. At the levels I was going over 5V (i.e., clipping the preamp output), I still didnt come anywhere close to 5V. i think the closest i came to was 2.9V.

what do you guys think is the last unclipped volume level i should set my sub and component amps to?

again, PLEASE TAKE A LOOK AT THIS GRAPH!! it took a long time to make:

http://i39.photobucket.com/albums/e164/fcelau1/graphofpreampvoltages.jpg

Click to read more...

 

[frankiebones 10+ year member]

i also noticed some interesting things about the way engaging diff sound processors impacts the preamp voltage, good read i think. in all the experiments conducted below, everything except the factor being changed was kept constant, including test tone frequency being used, all other processing not mentioned, all EQ bands, all crossover points and slopes, etc.

keeping volume at 45, the test tone, here are the voltage outputs as the differed from one pre-made EQ band to the next:

flat - 1.61 V

super bass - 4.81 V!!!

powerful - 2.31 V.

natural - .84 V.

vocal - .78 V

my own EQ setting - 2.75 V.

--

playing enter sandman at volume 60/62 with all the processing that i used when making all the above readings, the highest the preamp output got was to 2.07 V.

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with a 50 Hz test tone, the volume at 48/62 I got the following reading while messing with the slope of the HPF while it was set at 80 Hz:

slope set to -12 dB/octave - 1.39 V.

slope set to -6 dB/octave - 1.97 V.

slope to to 0 dB/octave (pass thru) - 3.70 V.

--

BBE Processing Test

volume at 54,

BBE off: .94

BBE -4: 1.43

BBE -3: 1.59

BBE -2: 1.77

BBE -1: 1.98

BBE 0 (diff than BBE OFF): 2.21

BBE +1: 2.47

BBE +2: 2.75

BBE +3: 3.09

BBE +4: 3.46

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Equalizer Test was weird, I knew that low end frequencies would impact preamp V. much more than higher since they require the HU to exert much more energy, but i didnt think that the voltage would be the same no matter how much i cut or boosted the high and mid EQ bands. i did all these with the volume at 44, and prior to testing the next EQ band, i put the one being tested back to flat.

12.5 KHz: (barely seemed to notice, althought the SQ was hugely affected)

-6 dB: 1.24 V.

-3 dB: 1.24 V.

+3 dB: 1.24 V.

+6 dB: 1.25 V.

200 Hz: (little movement, nothing like 2-3 bands down)

-6 dB: 1.21 V.

+1 dB: 1.24 V.

+3 dB: 1.24 V.

+6 dB: 1.26V.

125 Hz: (lil somethin something)

-6 dB: 1.13 V.

+1 dB: 1.24 V.

+6 dB: 1.31V.

80 Hz:

-6 dB: .92 V.

+/- 0 dB: 1.24 V.

+1 dB: 1.25

+6 dB: 1.55V

50 Hz:

+2 dB: 1.24 V

+6 dB: 2.63 V.

-----

Crossover Pt test:

Volume @ 47:

HPF @ 63 Hz: 1.69 V.

@ 80 Hz: 1.24 V.

@ 100 Hz: .77 V.

----

Compression/BMX test

I thought this one was pretty interesting bc i have not used this function much since i got the HU less than a month ago and i feel like it may have shed some light as to what its about:

volume and all other variables held constant:

COMP/BMX OFF: 1.86 V.

COMP 1: 1.57 v.

COMP 2: 1.86 v.

BMX 1: 1.86 V.

BMX 2: 1.78 V.

anyways, hopefully this has been interesting, maybe even informative. i have gotten a lot of advice on these boards since i joined and have yet to be in a position where i am knowledgeable to give any out so hopefully this will be good for my karma.

 

[johnecon2001 5,000+ posts]

Good test. But when you set your gains, all of that EQ and BBE crap is supposed to be off. You should try the next test with nothing else in the chain.

 

[frankiebones 10+ year member]

Good test. But when you set your gains, all of that EQ and BBE crap is supposed to be off. You should try the next test with nothing else in the chain.

i know ur supposed to set it with all the processing off but without an oscope, u run the risk of boosting ur signals past clipping once you set your gains and then add the processing.

here, since i have my processing down to a skill and do not turn things on and off from song to song, i figured the best way for me to get the maximum output out of my HU preamps was to figure out, given all the processing i use, when the HU will clip given the voltage i am asking of it.

 

[mannyb18b]

So use super bass? lol

 

[Ford302Redneck 10+ year member]

I need to take the time and do mine...

 

[blue93corsica 10+ year member]

get the matrix from audio control, that'll solve all your problems

 

[luvinthebass 5,000+ posts]

superbass eq puts a hump in the midbass response i noticed so i just use the flat and it sounds better

 

[ray@ss 10+ year member]

I'd like to "super-bass" your avatar.

 

[60ndown 10+ year member]

if it sounds distorted turn something down, if it doesnt your good. science is good an all, but in the end ......use your ears.