I have no idea which one, I got them bot changed at the same time...
It's not that big, it's just bigger than before. Woofer jumps a little.
I'm thinking could the thump be too much fot a ribbon tweeter without a passive crossover? It is not loud but it consist of bass signal, because the woofer jumps a little. Could it harm the ribbon?
Panomaniac, I have them now workin' ok, just 1 hour ago installed them. The man said that some of the foils were torn of and that caused the B channel to go mute.
I ran RMAA just a minute ago, I think the improvement are pretty nonexistent with new DAC and op-amps, what comes to measurements. The dynamic range and noise floor has dropped approx 2dB's because of the slightly higher gain (RMAA's gain meter goes higher, very close to +/- 0dB, before it was something like -1,5 - 1,1 dB)
What comes to the character of the sound, the sound is very pure and clear. I have been running Zero DAC and Maverick Tube Magic D1 connected straight to the amps for this time the DCXs were gone. DCX does not hinder the sound in any way, compred to those DACs. Like I said before, when I took DCXs out of the signal path when I got them modded, I could tell a little imprevement in the sound after DCX were gone... So some, although quite small, purification has happened in the sound.
Ops, I ment of course that noise floor has dropped and DR has risen, thus both have improved.
Since this is a DCX related question and many DCX users face the same situation, I might as well as it on this thread.
Have you put any hi-pass filter for your tweeter while using active crossover like DCX? Which is the best way to make a passive crossover to tweeter/ribbon. A cap in the speaker cable rises the capasitance quite heavy if i want to use lower hi-pass like 1000hz.
Mainly I would like to have a hi-pass for ribbons, since their impedance drops near zero at low freqs. Thjis could burn both ribbons and amp.
Have you put any hi-pass filter for your tweeter while using active crossover like DCX? Which is the best way to make a passive crossover to tweeter/ribbon. A cap in the speaker cable rises the capasitance quite heavy if i want to use lower hi-pass like 1000hz.
Mainly I would like to have a hi-pass for ribbons, since their impedance drops near zero at low freqs. Thjis could burn both ribbons and amp.
I would prefer to see a cap protecting the tweeters from DC and excessive LF signal.
This passive filter can be adjusted to the required crossover frequency.
However it will not fall @ -6dB/octave due to the varying impedance presented by the driver.
Now you can add on an active filter to bring up the required filter pole and Q.
If you wanted Butterworth 4pole then a 3pole Q=1 active filter will add to the single pole Q=0.7 passive filter to give ~4pole Q=0.7 total filter, with an error in the 4pole characteristic due to driver impedance variation.
Now you need to look at the driver's acoustic roll off. This has to be added to the active and passive filters you have.
The result is not a 4pole Butterworth. It will take a quite a bit of time and expertise to achieve the target filter.
The DCX should make this process much easier to implement than soldering on alternative components.
This passive filter can be adjusted to the required crossover frequency.
However it will not fall @ -6dB/octave due to the varying impedance presented by the driver.
Now you can add on an active filter to bring up the required filter pole and Q.
If you wanted Butterworth 4pole then a 3pole Q=1 active filter will add to the single pole Q=0.7 passive filter to give ~4pole Q=0.7 total filter, with an error in the 4pole characteristic due to driver impedance variation.
Now you need to look at the driver's acoustic roll off. This has to be added to the active and passive filters you have.
The result is not a 4pole Butterworth. It will take a quite a bit of time and expertise to achieve the target filter.
The DCX should make this process much easier to implement than soldering on alternative components.
Is this a good choice for passive level controlling after DCX, competitor for seletronic cotroller jan Jan's system? Is has 8 channel control, which I would need since I have two DCXs each driving 4-way channel.
It's name is the SPL Volume 8. Looks quite nice.
Description: Sound Performance Lab
and heres a review in Germany: http://www.spl.info/fileadmin/user_upload/produkte/volume2/beat_volumes.pdf
Is there a cheaper 8ch controller around? It could be whole passive controller also, just eight potentiometers put in to a box without any transformer.
edit: would some Behringer's mixer work?
It's name is the SPL Volume 8. Looks quite nice.
Description: Sound Performance Lab
and heres a review in Germany: http://www.spl.info/fileadmin/user_upload/produkte/volume2/beat_volumes.pdf
Is there a cheaper 8ch controller around? It could be whole passive controller also, just eight potentiometers put in to a box without any transformer.
edit: would some Behringer's mixer work?
Last edited:
Hi Andrew, I'm going to use that hi-pass filter only for ribboons' and amplifier's protection, the real hi-pass will be done with DCX. The passive hi-pass could be set to 1000hz and the real hi-pass to 3000Hz with DCX.
Because DCX thump when powering it up/-off, I think it would be wise to be safe than sorry with burn ribbons,m which are quite pricey (Fountek NeoCD3.0)
I'm not sure if i need any hi-pass filter I I could mod my DCX's starting regime so it would not thump at the power up/-off. Is there such a mod?
Theres still a possibilty that I might by mistake turn off the hi-pass filter of the ribbons.
The power consumption is trivial. Leave the bugger ON all the time, so no thumps.
Concerning the passive level control, this is very very interesting. XLR input and outputs, whole passive system, cheap.
One could add these as many as one needs.
TC ELECTRONIC LEVEL PILOT - Thomann Verkkokauppa
Is there possibly a better solution than this? I half-ready to order them
Information on manufacturer's website: http://www.tcelectronic.com/LevelPilot.asp
Edit: Here's another one, but not quite as good looking as TC electronics and does not have XLR outputs but instead jack outputs: http://www.thomann.de/fi/sm_pro_audio_nano_patch.htm
One could add these as many as one needs.
TC ELECTRONIC LEVEL PILOT - Thomann Verkkokauppa
An externally hosted image should be here but it was not working when we last tested it.
Is there possibly a better solution than this? I half-ready to order them
Information on manufacturer's website: http://www.tcelectronic.com/LevelPilot.asp
Edit: Here's another one, but not quite as good looking as TC electronics and does not have XLR outputs but instead jack outputs: http://www.thomann.de/fi/sm_pro_audio_nano_patch.htm
Last edited:
Concerning the passive level control, this is very very interesting. XLR input and outputs, whole passive system, cheap.
One could add these as many as one needs.
TC ELECTRONIC LEVEL PILOT - Thomann Verkkokauppa
An externally hosted image should be here but it was not working when we last tested it.
Is there possibly a better solution than this? I half-ready to order them
Information on manufacturer's website: TC Electronic | Level Pilot
Edit: Here's another one, but not quite as good looking as TC electronics and does not have XLR outputs but instead jack outputs: SM PRO AUDIO NANO PATCH + - Thomann Verkkokauppa
You must know the impedance levels of this control (and see it they are compatible with your system) to be sure. That's the critical issue with passive controls.
jd
Looks interesting, but I notice that they don't spec the tracking between sections. Suspicious.
Also, you can't individually trim channels to compensate for differences in amp or speaker sensitivity between channels. That's one of the things I specifically addressed in my unit.
And they don't have a remote control
jd
Do you have leds on the output channels? If so, the DSP works OK and the signal is going to the DACs.
jd
Thanks for the answers!
Is't it that the passive atteniation of the signal has always be done the same way (same values for wanted attenuation level) and therefore with same impedance?
If this is not the case, then:
My hifi amps have input impedance of 20Kohms (not stated does it concern both balanced and unbalanced inputs, but they have both).
Sub amps have 20Kohms balanced and 10Kohms unbalanced.
Behringer states that DCX's output impedance is approx. 160 ohms at 1kHz.
Those values I told are pretty basic allround values used at the majority of equipment. I think that the volume device has been designed to be used with normal kind of setups.
But how big would the impedance of this analog volume controller have to be that it would matter even the slightest? 100 ohms, 1000 ohms, 5000 ohms? I think we are talking about something like -6dB - -20dB attenuation that I will be using. So not super heavy attenuation and therefore greatly higher impedance of the analog volume controller. I think even -6db could suffice, just as much as I need to reduce the hiss to unaudible levels.
Last edited:
I had the DCXs repaired already
. They are working ok.To the whole forum: By the way, I previously mentioned that they might hear up a little bit more after changing the op amps and DACs. Well this is he case, but the cover of the DCX is hardly more warmer, maybe one or two degrees more. Just run them both on top of each other for the whole yesterday and they get only a bit warm. So no worries about DCX's getting too hot.
a passive pot has the highest output impedance @ -6dB and is ~25% of pot value.
Rs=160r & 10k pot has output impedance varying from zero to 2540r.
If you run medium to high capacitance after that you will lose treble, no problem with the bass channels, should not be a problem with the mid channels, definitely a problem with the treble channels.
If the 8 pots in that passive are 20k or higher then don't even consider using it to attenuate the signals to your power amps.
But are there buffers in that 8channel attenuator? It has power but for what?
From what I have read, the linked TC passive potentiometer is totally invisible in the signal path.
Here are some commercial speech about it:
I think I could also post some user commets from here: TC Level Pilot - Gearslutz.com
We use them at Double Helix and actually pretty impressive for the price/performance. No audible coloration, ultra quiet. Thumbs up from me
That comment that it is used with Genelecs monitors mean alot since genelec has almost the most neutral and hi-def upper register I know of. It would definitely be audible if some of that clarity would be missing.
I think it would be ok to use these? What dou you think Andrew? Three level pilots are the most inexpensive (seemingly high quality) commercial method I know of, that's what makes them interesting.
I'm planning to use them with tweeters, midrange and midbass, all are played with 20kohm input impedance stereo hifi-amplifiers. My sub amps have gain control on their own since they are PA-amps.
Last edited:
This thread is HUGE...
I have a DCX and I'd like to know a little about upgrading it. I've been reading through this topic for some time now, but I haven't been able to find out what mods are needed and to what end exactly.
I'm happy with what the DCX does. I believe its sound is transparent to my ears. There are two things I'd like to remedy:
1) It's hissy. I don't generally hear it, but when I'm listening to music at a very low level and it's quiet, It's audible.
2) It seems sensitive to thoughtless wiring or mediocre wires, leading to hum. If this is not an easy fix, I'll just have to be more careful when wiring and get me some better cables.
Now I'm more of a speakers man then an electronics man. Would anyone please tell me if the problems I'm experiencing are easily fixed. Direction to certain relevant pages of this topic would also be much appreciated.
I have a DCX and I'd like to know a little about upgrading it. I've been reading through this topic for some time now, but I haven't been able to find out what mods are needed and to what end exactly.
I'm happy with what the DCX does. I believe its sound is transparent to my ears. There are two things I'd like to remedy:
1) It's hissy. I don't generally hear it, but when I'm listening to music at a very low level and it's quiet, It's audible.
2) It seems sensitive to thoughtless wiring or mediocre wires, leading to hum. If this is not an easy fix, I'll just have to be more careful when wiring and get me some better cables
.Now I'm more of a speakers man then an electronics man. Would anyone please tell me if the problems I'm experiencing are easily fixed. Direction to certain relevant pages of this topic would also be much appreciated.
Hi Keyser - yes, it's quite a thread!
If you are happy with the DCX except for the hiss and hum, I surmise that your power amps have too much gain. If they have a volume pot on the inputs, turn it down - then drive the DCX harder. If not, you'll want some sort of attenuation in front of the amps.
We can figure that out here.
If you are happy with the DCX except for the hiss and hum, I surmise that your power amps have too much gain. If they have a volume pot on the inputs, turn it down - then drive the DCX harder. If not, you'll want some sort of attenuation in front of the amps.
We can figure that out here.
I almost completely removed the hiss problem of the DCX by means of replacing the power supply capacitors and those on the DSP board with higher quality ones, and when possible with bigger values.
On the supply board I used Very Low Imp Panasonic with higher value than the original, all bypassed with .1uF, all the 10uf surrounding the DAC, ADC and the 8412 were replaced with OS-CONs, same destiny for the caps on the DSP board just after the power connector.
Moreover I tweaked the 8.7V that goes to the 7805 responsible of the Analog 5V: I cut the wire and put in place a double RC filter with 1Ohm + 1200uF, with the scope showing huge improvement. the 5V Analog and the 3.3V derived from it have a much better look.
Replaced also the OP-AMPS right after the DACs with National ones
On the supply board I used Very Low Imp Panasonic with higher value than the original, all bypassed with .1uF, all the 10uf surrounding the DAC, ADC and the 8412 were replaced with OS-CONs, same destiny for the caps on the DSP board just after the power connector.
Moreover I tweaked the 8.7V that goes to the 7805 responsible of the Analog 5V: I cut the wire and put in place a double RC filter with 1Ohm + 1200uF, with the scope showing huge improvement. the 5V Analog and the 3.3V derived from it have a much better look.
Replaced also the OP-AMPS right after the DACs with National ones