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Re: Active setup help and recommendations

Reply #25
- You never said how much attenuation there is in the current passive design.  

Because I don't know, but this an original crossover from TAD made to use the woofer and compression driver that I use. Without a rotary l-pad it's ok so I guess there's a 13 db attenuation. First post I gave sensivity specs of woofer and compression drivers.

- You can't go by the raw driver specs.   The output from the compression driver will vary depending on the horn and the output from the woofer will depend on the cabinet design.

This a clone of a pioneer/TAD design. If you need more details, but I don't see what the horn has to do with gain?

http://www.geocities.jp/arai401204/Horn/A290/A290.html

- From what you've said, you are using two different amplifiers and the gains may be different.

True that's what I specified in first post. Both amp are integrated amplifiers (I gave link to specs) and I'll bypass the preamp section, so I guess no more volume pot.

Re: Active setup help and recommendations

Reply #26
Current crossover is 800hz.

Compression driver + horn are designed to go to 600hz.

Pioneer/TAD did 650hz for two models and one at 800hz but allow double woofers (using the same slopes W -36db/oct Comp D -12db/oct).

I want an active system to test at 600hz or 650hz. I don't want to spend more money than the miniDSP, that's why I listed the amplifiers I own right now.

Speakers are up ans running for 3 years now. They measure well, so as my room with treatment.

Now I just want to know what could be the issues with my plan. If it's clear that it won't work O won't buy the miniDSP. I don't need help for room treatment and measurements, no help for crossover setup.

Re: Active setup help and recommendations

Reply #27
Quote
This a clone of a pioneer/TAD design. If you need more details, but I don't see what the horn has to do with gain?
The cabinet & horn change the dB output.    So I don't trust that 13dB number.

Plus, at 16 Ohms you have half the power at the same voltage (I assume the  woofer is 8 Ohms?).   Half the power is -3dB so you'd be down to a 10dB difference (with matched amplifiers).
 
More gain = more output.  Less gain + less output.    For example, If there is really a 13dB difference and the woofer amplifier has 13dB more gain (unlikely) every everything is OK.    But, if the high-frequency amplifier  has more gain than the woofer amp, that makes things worse.

Re: Active setup help and recommendations

Reply #28
Quote
This a clone of a pioneer/TAD design. If you need more details, but I don't see what the horn has to do with gain?
The cabinet & horn change the dB output.    So I don't trust that 13dB number.

Plus, at 16 Ohms you have half the power at the same voltage (I assume the  woofer is 8 Ohms?).   Half the power is -3dB so you'd be down to a 10dB difference (with matched amplifiers).
 
More gain = more output.  Less gain + less output.    For example, If there is really a 13dB difference and the woofer amplifier has 13dB more gain (unlikely) every everything is OK.    But, if the high-frequency amplifier  has more gain than the woofer amp, that makes things worse.


Yep woofers are 8 ohm.
Cabinet
http://www.geocities.jp/arai401204/Enclosure/E170/E170.html
No amps are not matched : Pioneer 110w (8ohm) on woofer
Luxman 50w (8ohm) on comp drivers.
So I guess luxman has less gain than pioneer.
Specs are available with links from the first post.

For me going active allow me to use two different amplifiers : one more powerfull for the 16" woofer and a less powerfull amplifier with a high sensitivity comp driver. And I think that's something comon to Do? I don't see the point of using the more powerfull amp on horn.

Re: Active setup help and recommendations

Reply #29
For amplifier gain

110w @8hom with a 97db woofer = 20.4 db of gain
25w @16ohm (I halved the 50w @8ohm published by manufacturer) with a 110db CD  = 14 db of gain.

But anyway why on the hell I'll use all this amount of gain? I use fractions of a watt at normal listening level

Re: Active setup help and recommendations

Reply #30
So basically I'll have to attenuate ~7 db (if the horn or cabinet don't change the sensitivity of the drivers. I'll try to measure it for fun)?

I can do this with the miniDSP output gain or with a L-PAD right?

Re: Active setup help and recommendations

Reply #31
Quote
For amplifier gain

110w @8hom with a 97db woofer = 20.4 db of gain
25w @16ohm (I halved the 50w @8ohm published by manufacturer) with a 110db CD  = 14 db of gain.
Gain is independent of power.   A lower power amplifier can have more gain.

i.e.  Amplifier A is a 100W amp and Amplifier B is a 50W.

Amplifier A might put-out 10 Watts with 1 Volt in.   Amplifier B might put-out 20W with 1V in.   

Typically, you don't see a "gain" spec.   You might find a "sensitivity" spec that says "full power at 1V in", or "full-lower at -10dBV in".    

Gain (in dB) is actually voltage gain.   i.e. 20dB gain is 10V out with 1V in.    They don't give you voltage-out but you could calculate it (if you have the sensitivity spec.).

Amplifiers are (approximately) "constant voltage" devices.   Of course the voltage isn't really constant because it depends on the program material and the volume control setting.  It means voltage is independent of the impedance load.

10W into 8-Ohms is 12.5V.    If the amplifier is putting-out a 12.5V test tone and we disconnect the speaker it still puts-out (approximately) 12.5V, but zero Watts.    If you connect a 16-Ohm speaker you'll get 12.5V and 5W.  

However, if the amplifier is putting-out full power and you connect a lower impedance speaker the voltage may drop, and if it does the amplifier will clip.     Most solid state amplifiers are rated for twice the power at 4-Ohms but sometimes you'll seem the same power rating at 4 and 8 Ohms.   But, the voltage gain is the same (up to the point of clipping).

If you connect too-low of an impedance the amplifier might overheat and shut-down or burn-up.

The power-outlet in your house is also constant voltage...  The same voltage is present when nothing is plugged-in or if a 100W lamp or a 1200W toaster is plugged-in.   The power & current depend on the resistance of the load.   If you draw too much current the circuit breaker blows and voltage drops to zero.




--------------------------------------------------------------------------------
Quote
But anyway why on the hell I'll use all this amount of gain? I use fractions of a watt at normal listening level
In that case, you can potentially use the lower-power amplifier for the woofer if it has more gain. 

Have you checked to see which amp is "louder"?    You could connect one amp to the left speaker and the other to the right to see which is louder (if there's a difference).   Typically, the higher-power amp would have more gain but you can't be sure of that.

...Since your power amps don't have volume controls you can't change the gain of the power amps.   You can only adjust the gain (or attenuation) of the preamp



Re: Active setup help and recommendations

Reply #33
I re-checked the miniDSP manual  and there's -72db of gain attenuation, even with -12db I still have plenty of room, I think there's no reason for worrying. With the l-pad I'll have the same gain on all 4 outputs channels.  I want to be able to crank the speakers from time to time.

Ok 8)

The NF of you active system will be very bad, the Lpads are here to improve that parameter only , without them you will hear a huge noisefloor (and all its audible artifacts)
I have 28dB on my compressions and 6dB and my woofers, the MP3 sound perfect with no artifacts at all  :D

The levels shoud be adjusted later IMHO, measurements will give you the way to do it especially if there are a lot of reflexions, you are using wide dispertion biradial horns of the reference desing close to the walls... the soup of reverberations will affect the levels.


Re: Active setup help and recommendations

Reply #34
The levels shoud be adjusted later IMHO, measurements will give you the way to do it especially if there are a lot of reflexions, you are using wide dispertion biradial horns of the reference desing close to the walls... the soup of reverberations will affect the levels.

I'm working on this. There's less reflexions already with the panels that I have. I'll receive 6 - 2"x36x48 comfortboard this week (I hope).

Re: Active setup help and recommendations

Reply #35
I'm working on this. There's less reflexions already with the panels that I have. I'll receive 6 - 2"x36x48 comfortboard this week (I hope).

What kind of absorption do you expect from these panels ?
Have you a rough idea ?

Re: Active setup help and recommendations

Reply #36
I'm working on this. There's less reflexions already with the panels that I have. I'll receive 6 - 2"x36x48 comfortboard this week (I hope).

What kind of absorption do you expect from these panels ?
Have you a rough idea ?
2" will turn down the treble non-linearly, so that the reflections are even more unlike the onset wavefront. Blind tests show this to be worse perceptually for a variety of reasons, but belief in nonsense and the visual/expectation aspect will trump that and it will in extreme likelihood, "sound" better. The studios use stuff that look similar, so you should too.
It's all explained in Toole's IQ test, excuse me, writings.

Loudspeaker manufacturer

Re: Active setup help and recommendations

Reply #37
I'm working on this. There's less reflexions already with the panels that I have. I'll receive 6 - 2"x36x48 comfortboard this week (I hope).

What kind of absorption do you expect from these panels ?
Have you a rough idea ?


First I want to lower reflexions. Still don't know if I'll do 6 x 2'' panels or 3 x 4'' panels. The 4 panels that I built last year are 4'' installed at first reflexion points. Absorption will be welcome, but for now I have +/- 5db to almost 20hz to 20khz and a big part at  +/- 3db. Since I take the frequency response with a grain of salt I guess it's pretty good. I don't know yet if I'll hear a difference once I'll get the new panels on walls. I guess I'll have to sacrifice myself and listen to a lot of music for the coming days :p

I'll try both configuration (2'' or 4'') before final installation And I'll measure (almost) all  the possible combinations.

If you can go to this forum you'll find a part measurements I took today.
http://the-audio-expert.freeforums.net/thread/458/thicker-more-panels?page=3&scrollTo=4037

or check the REW file I attached

Re: Active setup help and recommendations

Reply #38
Oups notes are in french.

First measurements siting square, ears at same level has the center of the horn.
Second 4'' lower (siting late at night lol)

I took  a lot of measuements today 40 to 50, several for each change to see if results are consistent.

Re: Active setup help and recommendations

Reply #39
2" will turn down the treble non-linearly, so that the reflections are even more unlike the onset wavefront. Blind tests show this to be worse perceptually for a variety of reasons, but belief in nonsense and the visual/expectation aspect will trump that and it will in extreme likelihood, "sound" better. The studios use stuff that look similar, so you should too.

It is an empirical aproach, some people are adjusting their "soup" of reverberations to their taste and perform inaccurate measurements in order to interpret them as a confirmation bias.
IMHO, it seems to be more a guru job than a real technical work.

Re: Active setup help and recommendations

Reply #40
It is an empirical aproach
Round these parts it's called sighted, belief approach.

Btw, needless to say, didn't register at other site to see expanded full size graphs, but the speaker FR snapshot appear to be 10db (!!) scaling, which would make the native onset response rather poor (assuming competence in the measurement/system). If that is with DSP, it's frankly horrific.
Under those pathological circumstances, by all means pad the room with gauze/bandaids, aka the "less worse" option.
Loudspeaker manufacturer

Re: Active setup help and recommendations

Reply #41
REW's mdat file is attached, so no need to go to forum to see graph.

83% of frequency response is +/- 3b, and 92% +/-5 db, it's not that hard to see that with a 10 db scale. Note that scale can be adjusted freely with REW.

As for freq response I always take those graphs with a grain of salt since it change with a couple of inches mic placement. However acoustic panels allowed me to get a fixed image (a larger window). Before singer's position slip from center to left or right with small head mouvements. Blinded listening revealed the same thing.

Now I can move freely at my siting position without loosing singer and instrument "placement". Measurements at different position confirmed it since frequency response shape is quite "stable" but with db change. It can be easily seen with the spl graph.

Now at this point I'll keep my subjective point of view for me. But I have a stable image and it is something that I really appreciate. Other panels will help me with the other reflexions, absorption coeficient at this point doesn't matter to me. Comfortboard are easy to work with and can look good, it can even help to hold my beer while playing rock band with my friend.

I won't do ABX with room acoustic in my house. No one told me or suggested me to do acoustic treatment. I experienced adding stuff  2 years ago it gives me benefits that I appreciate.

Again ajinfla you're trying to troll, and you're thread crapping my post. I've read your points about this in the other post you link, it's time to move on.

Re: Active setup help and recommendations

Reply #42
Before singer's position slip from center to left or right with small head mouvements. Blinded listening revealed the same thing.
¯\_(ツ)_/¯
Loudspeaker manufacturer

Re: Active setup help and recommendations

Reply #43
REW's mdat file is attached, so no need to go to forum to see graph.
83% of frequency response is +/- 3b, and 92% +/-5 db, it's not that hard to see that with a 10 db scale. Note that scale can be adjusted freely with REW.

Your NF is high, do you hear it ?
Have you applied some EQ ?

PS : imaging should be a space oddity because of your horns firing on the walls.

Re: Active setup help and recommendations

Reply #44
Don't know where the mic is, but if the measurement setup isn't broken, the loudspeaker is.



Unsurprising no one said a word on the iso-ward forum. Casting pearls before the swine.
I hope the polars aren't worse. This thing needs some "treatment" alright.
Loudspeaker manufacturer

Re: Active setup help and recommendations

Reply #45
REW's mdat file is attached, so no need to go to forum to see graph.
83% of frequency response is +/- 3b, and 92% +/-5 db, it's not that hard to see that with a 10 db scale. Note that scale can be adjusted freely with REW.

Your NF is high, do you hear it ?
Have you applied some EQ ?

PS : imaging should be a space oddity because of your horns firing on the walls.

Noise floor? +/- of being flat response.

Dead silent setup, no EQ.

Re: Active setup help and recommendations

Reply #46
I'll call major Tom to see if it's the case

Re: Active setup help and recommendations

Reply #47
I'll call major Tom to see if it's the case

On your measurements, the NF is high...
So, you are trying to find a tonal equilibrium on a very, very difracted soundfield, why not, but it is a llittle naive to expect anyting good concerning the imaging.

Re: Active setup help and recommendations

Reply #48
I'll call major Tom to see if it's the case

On your measurements, the NF is high...
So, you are trying to find a tonal equilibrium on a very, very difracted soundfield, why not, but it is a llittle naive to expect anyting good concerning the imaging.


Where do you see the noise floor?

Re: Active setup help and recommendations

Reply #49
Quote
For amplifier gain

110w @8hom with a 97db woofer = 20.4 db of gain
25w @16ohm (I halved the 50w @8ohm published by manufacturer) with a 110db CD  = 14 db of gain.
Gain is independent of power.   A lower power amplifier can have more gain.

i.e.  Amplifier A is a 100W amp and Amplifier B is a 50W.

Amplifier A might put-out 10 Watts with 1 Volt in.   Amplifier B might put-out 20W with 1V in.   

Typically, you don't see a "gain" spec.   You might find a "sensitivity" spec that says "full power at 1V in", or "full-lower at -10dBV in".    

Gain (in dB) is actually voltage gain.   i.e. 20dB gain is 10V out with 1V in.    They don't give you voltage-out but you could calculate it (if you have the sensitivity spec.).

Amplifiers are (approximately) "constant voltage" devices.   Of course the voltage isn't really constant because it depends on the program material and the volume control setting.  It means voltage is independent of the impedance load.

10W into 8-Ohms is 12.5V.    If the amplifier is putting-out a 12.5V test tone and we disconnect the speaker it still puts-out (approximately) 12.5V, but zero Watts.    If you connect a 16-Ohm speaker you'll get 12.5V and 5W.  

However, if the amplifier is putting-out full power and you connect a lower impedance speaker the voltage may drop, and if it does the amplifier will clip.     Most solid state amplifiers are rated for twice the power at 4-Ohms but sometimes you'll seem the same power rating at 4 and 8 Ohms.   But, the voltage gain is the same (up to the point of clipping).

If you connect too-low of an impedance the amplifier might overheat and shut-down or burn-up.

The power-outlet in your house is also constant voltage...  The same voltage is present when nothing is plugged-in or if a 100W lamp or a 1200W toaster is plugged-in.   The power & current depend on the resistance of the load.   If you draw too much current the circuit breaker blows and voltage drops to zero.




--------------------------------------------------------------------------------
Quote
But anyway why on the hell I'll use all this amount of gain? I use fractions of a watt at normal listening level
In that case, you can potentially use the lower-power amplifier for the woofer if it has more gain. 

Have you checked to see which amp is "louder"?    You could connect one amp to the left speaker and the other to the right to see which is louder (if there's a difference).   Typically, the higher-power amp would have more gain but you can't be sure of that.

...Since your power amps don't have volume controls you can't change the gain of the power amps.   You can only adjust the gain (or attenuation) of the preamp



I was looking at emotiva amp as a final setup (amp listed in first post are for testing)

MiniDSP 2x4 HD : input 2v or 4v @  10k ohm
                             output 2v @ 560 ohm

PT-100 preamp : Max output 4v ?ohm

Amp : A-100 input 600mV ?ohm with 8 ohm load
                      50 w - 8 ohm
Amp - A-300 input 1.2 v 27k ohm with 8 ohm load
                      Gain 29 db
                     150w 8 ohm
Driver 1 - sensitivity 110db - 16 ohm
Driver 2 - sensitivity 97db - 9 ohm

What would be the gain structure ( I sent an email to emotiva to get missing information

 
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