Ramblr,
great you found the cap with different / wrong value.
If we have speakerdrivers, which have all the same sensitivity (dB / W /m), it is my experience, that the subwoofer / bass needs most of the power out of the amps, followed by the middrivers, lowest power to the tweeters. And we have not looked at strange impedance dips in some frequency ranges, which make the 'life' of an amp not better...
Greets
Dirk
great you found the cap with different / wrong value.
If we have speakerdrivers, which have all the same sensitivity (dB / W /m), it is my experience, that the subwoofer / bass needs most of the power out of the amps, followed by the middrivers, lowest power to the tweeters. And we have not looked at strange impedance dips in some frequency ranges, which make the 'life' of an amp not better...
Greets
Dirk
Dirk,
I have been playing with the settings for a good hour. To get good bass I have to turn the high pass buffer down to about half way, with the low pass buffer wide open, and then turn up the Eleven that is acting as a preamp. The KA-801 powering the subwoofer is then turned up to about 3/4 volume. Just trying to determine if I have this built right; or should I be re thinking my component choices?
Thanks for your help!
I have been playing with the settings for a good hour. To get good bass I have to turn the high pass buffer down to about half way, with the low pass buffer wide open, and then turn up the Eleven that is acting as a preamp. The KA-801 powering the subwoofer is then turned up to about 3/4 volume. Just trying to determine if I have this built right; or should I be re thinking my component choices?
Thanks for your help!
Hello Ramblr,
this sounds all good to me. Playing around with the volume settings at the input of the lowpass and highpass is competely normal.
It also depends on the power of the amps and the efficiency / sensitivity of the drivers how far you have to adjust the volume up or
down.
Adjust the lowpass to full volume at the 6-24AXO. Then adjust the highpass till you get a nice balance to your sub.
At the preamp you adjust the overall volume.
You will need more time and listening. This is part of the game. I think nothing is wrong.
Dirk
this sounds all good to me. Playing around with the volume settings at the input of the lowpass and highpass is competely normal.
It also depends on the power of the amps and the efficiency / sensitivity of the drivers how far you have to adjust the volume up or
down.
Adjust the lowpass to full volume at the 6-24AXO. Then adjust the highpass till you get a nice balance to your sub.
At the preamp you adjust the overall volume.
You will need more time and listening. This is part of the game. I think nothing is wrong.
Dirk
I am
I succeed setting the active crossover board at 1800hz. Now everything sounds right and fabulous. I have not tested the result with rew yet, will do it later. I think the active increase the sound scale of music significantly, way deeper and wider. I guess using biamp to drive high and low frequency range separately contributes a lot.
Hello Ramblr,
I had no access to M. Rothachers simulation software for the 6-24AXO yesterday. I think he is working on his computer / server?
As early as there is the possibility, I will check your R- and C- values in the simulation.
Cheers
Dirk
I had no access to M. Rothachers simulation software for the 6-24AXO yesterday. I think he is working on his computer / server?
As early as there is the possibility, I will check your R- and C- values in the simulation.
Cheers
Dirk
Man - I wish you could make easier than ordering 5 different pieces.
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Finally got it 100%. Thought I would throw up a few pics. When I was researching I wished there were more photo of completed.
No. Use the Elna. The Elna audio grade caps are fine.
Use a Wima PP film 100v 100nf that fits in the pcb.
The above are what Pass Labs uses.
The low ESR of the PP film cap and the dielectric will mean the signal is shunted through the film cap above 75 hertz in to a 20kohm impedance.
The electrolytic cap is there to set the low frequency time constant and keep the phase shift well below the audio bandwidth. The important thing is that no voltage drop occurs across the capacitor in the audio band as this will cause a sharp rise in THD at low frequencies. The high odd order harmonics 5,7,9,11,13) what may be perceived as hardness in the sound of electrolytic capacitors. So by pushing the -3 db point very low this means resistive reactance of the capacitor (rising impedance) occurs at close to DC.
In my observation and informal discussions on coupling caps with The Master the Jfets and the simple exotic circuits have a much greater influence on sound quality than you might realise. I agree. Remember that most recordings have numerous electrolytics caps and 5532 monolithic op amps in the signal path.
That is great news. I am very happy for you.
I have seen this active crossover put a happy smile on peoples faces. It literally has very little contribution to the signal.
While on the subject of resistor ladder pots. I'm half way through my tri-amp build, started earlier this year (yes, I'm that slow).
I've seen other builds in here with three level pots per 6-24XO board. That's six pots for two channels of Lo, Mid, Hi. I wonder if the Mid pot is wasted money, can't see the point. Would anyone foresee any issues with using two pots per channel - only the Lo and Hi - with the Mid level shorted to zero ohms? Or do I misunderstand the reason for the pots?
I've seen other builds in here with three level pots per 6-24XO board. That's six pots for two channels of Lo, Mid, Hi. I wonder if the Mid pot is wasted money, can't see the point. Would anyone foresee any issues with using two pots per channel - only the Lo and Hi - with the Mid level shorted to zero ohms? Or do I misunderstand the reason for the pots?
The level pots are not volume pots.
In this application the level pots are to account only for differences in driver efficiency and power amplifier voltage gain.
They should be adjusted individually using an AC voltmeter or an analyser such as REW.
Drivers can have some variation in efficiency matching and this should be measured with a near field spl measurement using a sine wave and REW or other analyser such as ARTA or Clio pocket 3.
The volume adjustment should come from the preamplifier.
In this application the level pots are to account only for differences in driver efficiency and power amplifier voltage gain.
They should be adjusted individually using an AC voltmeter or an analyser such as REW.
Drivers can have some variation in efficiency matching and this should be measured with a near field spl measurement using a sine wave and REW or other analyser such as ARTA or Clio pocket 3.
The volume adjustment should come from the preamplifier.
Hello macka,
you are right, that the overall volume control will be done with the volumepot of the preamp.
The trimpots on the input of each filterstage (inputbuffer) are nothing else than volumepots to adjust / attenuate the inputsignal
to get the same spl- / volume-level between the different filterstages dependent on amps and loudspeakerdrivers in use. But I think, that we mean the same - only in different words.
Greets
Dirk 😉
you are right, that the overall volume control will be done with the volumepot of the preamp.
The trimpots on the input of each filterstage (inputbuffer) are nothing else than volumepots to adjust / attenuate the inputsignal
to get the same spl- / volume-level between the different filterstages dependent on amps and loudspeakerdrivers in use. But I think, that we mean the same - only in different words.
Greets
Dirk 😉
Thanks for the tips. I understand they are not volume controls. Rethinking it after your comments, I'll leave the pots out. I had initially thought about it as a way of easily changing levels, while ditching the variable resistors as I will be doing with the filter stages. Everything with discrete values. The only reason I'd be changing levels is the rare occasion I'm rebuilding my speakers or swapping out amps.
Seeing this is quite an involved process anyway and may include filter C/R swaps - especially in the case of a speaker change - there's not much to be gained (pun intended) by putting expensive ladder pots up front. I suppose it might be worth it for those that like to swap out amps on a regular basis.
Seeing this is quite an involved process anyway and may include filter C/R swaps - especially in the case of a speaker change - there's not much to be gained (pun intended) by putting expensive ladder pots up front. I suppose it might be worth it for those that like to swap out amps on a regular basis.
Hello maFrodite,
why don't you try the 6-24AXO with the 50kOhm - trimpots (at the input-buffers) recommended by Nelson Pass? Cheap, makes your audio signal levelling easy...
I think he used 1-turn - trimpots. You can use 25-turn - trimpots on the pcb.
Later you can decide to exchange the trimpots to something 'fancy'.
Only my thoughts
Greets
Dirk
why don't you try the 6-24AXO with the 50kOhm - trimpots (at the input-buffers) recommended by Nelson Pass? Cheap, makes your audio signal levelling easy...
I think he used 1-turn - trimpots. You can use 25-turn - trimpots on the pcb.
Later you can decide to exchange the trimpots to something 'fancy'.
Only my thoughts
Greets
Dirk