K-510 / K-691's ... horrible sound ... SOLVED

[babadono]

Emile, follow Chris's instructions and recommendations. That's my advice to you. After all the K510 and 691 are the hi freq section of the KPT-396s. They do not sound thin and tinny.

[Khornukopia]

1 hour ago, Emile said:

tried it without the miniDSP and all is fine

 

Can you post a screenshot of the miniDSP settings?

[Emile]

Many thanks  

 

All p-arametric eq's bypassed

Routing # 1 In to 0ut 1&3, 2 In to Out 2&4 ... 1&2 to Fortes, 3&4 to 510's

Crossover 1&2 to Fortes, 3&4 to 510's

 

Xover 2 same as above

 

Xover 4 same as above. Was playing with crossover slopes also ... 48 dB seemed worse than 24dB, worse than 12dB; no clue

 

Thanks, Emile

[PrestonTom]

Guys: i do not have this DSP box. It sounds like the OP is sending an attenuated analog signal to the DSPbox which will then perform an ADC conversion. Key question: is this DSP box "expecting" a consumer level signal (about 2 V RMS max) or is it "expecting" a Pro level signal (10-20 V RMS)?

 

Second question: Can this DSP box accept a digital signal or does it only take analog inputs? Will his source provide a digital output or is it only analog?

[Emile]

2 minutes ago, PrestonTom said:

Key question: is this DSP box "expecting" a consumer level signal (about 2 V RMS max) or is it "expecting" a Pro level signal (10-20 V RMS)?

Coming from my pre-amp ... certainly not more than 2V ... plus this miniDSP is a cheap $100 box  

[Chris A]

Tom,

 

I believe the issue is that there is no compensation for the big 1-4 kHz hump in response due to the controlled directivity horn (K-510) and 2" compression driver (k-691).  They all sound like Emile has described--until the proper flattening EQ is applied and the channel gains are matched.  Then it sounds much better.

 

For example--using the K-510 with a K-69-A driver:

 

 

Chris

[Khornukopia]

Your DSP settings look close enough for now, but the way you describe the sound, it seems as if the woofer is not getting signal. What happens when you physically bypass the miniDSP for the Forte power amp? Do not bypass the miniDSP for the tweeter circuit!

[Emile]

17 minutes ago, Khornukopia said:

What happens when you physically bypass the miniDSP for the Forte power amp? Do not bypass the miniDSP for the tweeter circuit!

Bypassing miniDSP to Forte's gives "clean" sound with miniDSP to 510's being "dirty/distorted."

Anyway I can try the 510's "direct" without blowing them up ... bass minimum on both preamp and amp????

[Chris A]

Since it seems to be so hard to measure, Emile...

 

Try the following PEQs in your miniDSP crossover, and set the channel gains of the K-510/K-691s down to -6 to start, then increment that gain towards "0" dB until it sounds about right:

 

[Khornukopia]

9 minutes ago, Emile said:

Bypassing miniDSP to Forte's gives "clean" sound with miniDSP to 510's being "dirty/distorted."

Anyway I can try the 510's "direct" without blowing them up ... bass minimum on both preamp and amp???? 

 

I would not run the K-691 tweeters without the crossover. I would leave them completely unplugged and just connect the Fortes, one as the bass unit and the other as the tweeter unit, until you figure out what is causing your condition with the miniDSP function. Have you used this exact miniDSP before with other speakers?

[Khornukopia]

19 minutes ago, Emile said:

sound with miniDSP to 510's being "dirty/distorted

 

Following Chris A's guidance posted above might be easier than my suggestion.

[PrestonTom]

I think there are two likely culprits. The most likely is what Chris has laid out. The other is what I was getting at. In consumer sound, "live level" is anywhere from 1/2 volt to 2 volts. If there is an attenuator (eg, preamp's level control) the output will be substantially less (perhaps 1/10 volt). In the world of pro sound, the levels are much, much higher (up to 15-20 volts).

 

So is the ADC on the DSP box trying to spread a tiny analogue signal over 16 bits (or more) since it "expecting" a pro level. In the worst case you would inadvertently be making the ADC in the DSP box "look" like a 6 bit converter rather than a 16 bit converter (this is why I suggested you  get familiar with the concept of "gain structure"). One way to get around this is by feeding DSP boxes a digital signal, rather than an analog signal. That is a much better way of doing things, although it makes the level control (volume knob) more involved. 

 

Certainly, follow through on Chris's strategy first. 

[Emile]

1 hour ago, Chris A said:

Try the following PEQs in your miniDSP crossover

Thank you Chris  

OK; cannot manually multiple inputs into this cheap box   Trying to import a .txt file to it with

1000   -8.3

1700   -3.4

3200   -4.9

11200  3.0

Hope I can try this later today  Haha ... test file  name is Chris_1.txt

 

Thanks, Emile

 

[Emile]

Well, that did not work   miniDSP says "Your biquad in your input file is not correctly formatted." Found another .txt file from an REW test I did with my Cornwall's ... reads as below ... no clue hoe to put Chris' numbers into this  

biquad1,
b0=0.9905020420057294,
b1=-1.9796369681078865,
b2=0.989238381654187,
a1=1.9796369681078865,
a2=-0.9797404236599164,
biquad2,
b0=1.0023540601136967,
b1=-1.9973351447848358,
b2=0.9950567601560919,
a1=1.9973351447848358,
a2=-0.9974108202697883,
biquad3,
b0=0.9760603225014789,
b1=-1.7224370293255478,
b2=0.8644258402549714,
a1=1.7224370293255478,
a2=-0.8404861627564504,
biquad4,
b0=0.9790833807883182,
b1=-1.9015934574485598,
b2=0.9423218411823171,
a1=1.9015934574485598,
a2=-0.9214052219706351,
biquad5,
b0=0.9998391405819421,
b1=-1.9988621118651455,
b2=0.9990592871108847,
a1=1.9988621118651455,
a2=-0.9988984276928269,
biquad6,
b0=1.0,
b1=0.0,
b2=0.0,
a1=0.0,
a2=0.0
 

[Chris A]

Try the following:

 

For Emile.txt

 

Chris

[Emile]

Thank you Chris ... AWESOME. Small question ... assume I put these in the Parametric EQ's (output 3&4) 

[Chris A]

Yes, it's the last option in the Filter: Tasks panel on the right hand side: "Export Filter Settings as Text"

[Chris A]

That picture actually doesn't look like the screen shot, above, from REW.

 

You can key in the values by hand from my original screen shot (reproduced again, below), as evidenced by the screen shot that you posted, just above.

 

[Emile]

OK; loaded into miniDSP channel 3&4 ... will try shortly ... have to feed my wife first  

[Chris A]

That looks much better.