DRC Designer is a front end for DRC-FIR to make it easier to use. There is a learning curve to use DRC directly with scripts but beyond that all the options will be available to you and it is a very comprehensive program and completely configurable.
There is a thread here with some good scripts and instructions that make using it reasonably simple. A convolution based alternative to electrical loudspeaker correction networks
With the ability to use convolution filters on the computer I suspect that a better transfer function for each driver could be realised by using Najda with IIR filters. Impulse correction or whatever phase manipulation is desired can be added in the convolution filter and DRC can do a very good job of that task.
Yeas Fluid you are right.
But I have used IIR filters and done a lot of fideling with them and now after moving to FIR does everything sounded much better. Some people talk about air in the sound. Every instrument or sound separated so that you can easily follow each instrument. Very nice.
So 1000 taps filters for each driver in Najda and whole band (speaker + room) corection with a Pc where you can use all the taps you need.
I did plan to use a Raspberry but there is not that much calculating power. Raspberry is not that cheep when buying one with more power, ram and adding all needed bits and peaces. Dated Win power can be found for less.
But I have used IIR filters and done a lot of fideling with them and now after moving to FIR does everything sounded much better. Some people talk about air in the sound. Every instrument or sound separated so that you can easily follow each instrument. Very nice.
So 1000 taps filters for each driver in Najda and whole band (speaker + room) corection with a Pc where you can use all the taps you need.
I did plan to use a Raspberry but there is not that much calculating power. Raspberry is not that cheep when buying one with more power, ram and adding all needed bits and peaces. Dated Win power can be found for less.
Attachments
I am in the process of resurrecting my Najda. Have confirmed that it works again. I have V1.1 board. I have a few questions:
1. Has anyone here used Najda over an extended period of time? Have you encountered any issues, such as data corruption (required a re-flash or re-configuration)? If so, what version do you have?
2. What is the latest firmware? I have 1.3.
1. Has anyone here used Najda over an extended period of time? Have you encountered any issues, such as data corruption (required a re-flash or re-configuration)? If so, what version do you have?
2. What is the latest firmware? I have 1.3.
Mine has been in almost daily use since the very beginning.
I've added and deleted presets countless times.
Never had any corruption issues.
Once I store new presets or delete, I always SW disconnect and then power off Najda to save the settings, before continuing to use.
I had the first version (red circuit board) for 4 years.
Now on 1.3 black board since 2018.
I only changed because I stupidly managed to give the 5v supply reversed +/-[emoji849]
I've added and deleted presets countless times.
Never had any corruption issues.
Once I store new presets or delete, I always SW disconnect and then power off Najda to save the settings, before continuing to use.
I had the first version (red circuit board) for 4 years.
Now on 1.3 black board since 2018.
I only changed because I stupidly managed to give the 5v supply reversed +/-[emoji849]
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analog input impedance
I am the lucky owner of two Najda Boxed units (assembled by Nick)!
I miss any information about the input impedance of the analog input. I suspect that it is pretty low, but I have no information on the true numbers. Does anybody knows something better about this?
The issue is the following. I changed my phono stage with an high quality vintage all tubes unit, this is well known to have a terrific dynamic. But when I connect to the Najda analog input some of the punch get lost, and a strange roundness is introduced which was not expected. It's not a problem of levels, setting the input sensitivity to 2Vrms the peaks are fine and the analog input scale seems well represented. The problem is with the dynamic and some excess smooth.
Looking at the circuit it seems that the input to the ADC is buffered, but I wonder whether the input impedance is lowish as in many modern ADC inputs. I can only explain what I hear with some impedance mismatch. Can it be?
I am the lucky owner of two Najda Boxed units (assembled by Nick)!
I miss any information about the input impedance of the analog input. I suspect that it is pretty low, but I have no information on the true numbers. Does anybody knows something better about this?
The issue is the following. I changed my phono stage with an high quality vintage all tubes unit, this is well known to have a terrific dynamic. But when I connect to the Najda analog input some of the punch get lost, and a strange roundness is introduced which was not expected. It's not a problem of levels, setting the input sensitivity to 2Vrms the peaks are fine and the analog input scale seems well represented. The problem is with the dynamic and some excess smooth.
Looking at the circuit it seems that the input to the ADC is buffered, but I wonder whether the input impedance is lowish as in many modern ADC inputs. I can only explain what I hear with some impedance mismatch. Can it be?
I use mine most days, for the last 7 years. The only issue I have is I need to turn the Nadja on last otherwise I sometimes it doesn’t work, think it’s a static thing with the analogue input. Turning the Nadja on and off seems to fix it. I had an issue about a year back when I disconnected whilst under NUC. I fixed the corruption that occurred ured - using the instructions recently shared.
Thanks for the feedback.
In the early days I had an incident (and at least one other person did, too) where the configuration was corrupted. The fix then was to always power down Najda by putting it into sleep mode first, never by removing power directly (i.e., with the power switch). I was never comfortable with having to do this and actually planned on installing a battery-powered backup circuit that would kick in and keep Najda alive in the case of a mains failure and then initiate sleep mode before dropping power finally.
Nick would not publish the schematic. This I had wished to inspect in order to check whether there might have been a design oversight, as I was not happy with having to add the mod without exploring on-board options.
This is what put me off completing the project. However, now I am tackling it again and I will make that power drop-out monitor if it proves necessary.
In the early days I had an incident (and at least one other person did, too) where the configuration was corrupted. The fix then was to always power down Najda by putting it into sleep mode first, never by removing power directly (i.e., with the power switch). I was never comfortable with having to do this and actually planned on installing a battery-powered backup circuit that would kick in and keep Najda alive in the case of a mains failure and then initiate sleep mode before dropping power finally.
Nick would not publish the schematic. This I had wished to inspect in order to check whether there might have been a design oversight, as I was not happy with having to add the mod without exploring on-board options.
This is what put me off completing the project. However, now I am tackling it again and I will make that power drop-out monitor if it proves necessary.
I believe I had the same experience today, although I currently don't have it connected to anything. I switched it on, but could not get it to wake up out of standby (I called it sleep mode above). After power cycling it again it worked.
I believe this is a known problem. It seems that the safe practice is to disconnect Najda within the NUC GUI before physically disconnecting.
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Mine after long period on standby does not wake up. I need to power cycle.
Also recently had some corruptions on display, strange but re-plugging LCD wires helps for that. Probably I need new wires.
Another issue is that in my case Najda hangs while connecting usb plug. If Najda is powered as last device then it's fine. Sometime ago I changed power supply and I'm not sure if this sarted to happen just after that or later, probably I need to retest with previous powersupply.
Also recently had some corruptions on display, strange but re-plugging LCD wires helps for that. Probably I need new wires.
Another issue is that in my case Najda hangs while connecting usb plug. If Najda is powered as last device then it's fine. Sometime ago I changed power supply and I'm not sure if this sarted to happen just after that or later, probably I need to retest with previous powersupply.
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@Shaun: Yes, I have firmware version 1.3, too - tried always to get the latest tricks from Nick.
@Shaun: Yes, decimation would have been a big step forward. First of all it is sad not to hear good news from Nick, but second to this it is sad that noone can continue his great work.
Power on/off process often requires two steps, if software is involved. I tried to manage this with the raspberry, succeeded....but only until volumio had to be updated. So I guess we have to live with this.
Najda is a bit shy: when I turn on power amps after Najda, there is a beep from the notebook running NUC, and Najda disconnects. Once understood I can deal with this.
@Vinylnvalves: This happens, when Najda is connected via analog input to my measuring equipment. Turning on the IMP after Najda is not healthy...
A strange thing is this: My speakers have a response nearly absolutely equal - measured using the analog input. Hearing music afterwards via digital input (coaxial S/P-DIF), I need to shift balance 2dB to the right.
Speedysteve7 had a similar theme a while ago but blamed it on the raspberry (connected via I2S!) or volumio, if I remember well.
@Shaun: Yes, decimation would have been a big step forward. First of all it is sad not to hear good news from Nick, but second to this it is sad that noone can continue his great work.
Power on/off process often requires two steps, if software is involved. I tried to manage this with the raspberry, succeeded....but only until volumio had to be updated. So I guess we have to live with this.
Najda is a bit shy: when I turn on power amps after Najda, there is a beep from the notebook running NUC, and Najda disconnects. Once understood I can deal with this.
@Vinylnvalves: This happens, when Najda is connected via analog input to my measuring equipment. Turning on the IMP after Najda is not healthy...
A strange thing is this: My speakers have a response nearly absolutely equal - measured using the analog input. Hearing music afterwards via digital input (coaxial S/P-DIF), I need to shift balance 2dB to the right.
Speedysteve7 had a similar theme a while ago but blamed it on the raspberry (connected via I2S!) or volumio, if I remember well.
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I am following this discussion about problems with switch on/off cycles. Are you talking about the kit/boards version? Or rather, this is also affects completed units, i.e. assembled and housed in a nice enclosure by Nick?
I am a bit scared because for some reason there is some problem with the mains where I live so that the main home circuit breaker switch off electricity completely.
I am a bit scared because for some reason there is some problem with the mains where I live so that the main home circuit breaker switch off electricity completely.
Same as me, but with 1.3 board version. But actually I did not assembled it by my self, bought it from my friend who was switching to other solution. He was who assembled it.
I don't remember all those happening with older/switching power supply. I need to switch it back for testing purposes.
Anyway lcd pcb is not soldiered nicely too (done by my friend, not by Nick) so I will re-soldier it also.
I don't remember all those happening with older/switching power supply. I need to switch it back for testing purposes.
Anyway lcd pcb is not soldiered nicely too (done by my friend, not by Nick) so I will re-soldier it also.
Your observation about the Nadja being 2 db hotter on the left channel with digital is something I have heard too, I just keep thinking its my ears. I think a digital input test signal would confirm if our ears are right or wrong.
As the analogue input is the weak link has any one come up with a better way of feeding an analogue signal into the Nadja? I have wondered if the Mtech Joplin is the answer for me to listen to vinyl bypassing the analogue input.. an expensive option though.
As the analogue input is the weak link has any one come up with a better way of feeding an analogue signal into the Nadja? I have wondered if the Mtech Joplin is the answer for me to listen to vinyl bypassing the analogue input.. an expensive option though.
@vinylnvalves: personally I listened to few digital RIAA solutions and never liked the results. My tube phono stage still sounds better to me. I think the problem is not the RIAA filtering but the ADC conversion.
On the paper the Najda has a good ADC but the problem is that input stage is designed with professional use in mind. Based on the estimate of my trusted technician its input impedance is well below 10K... which is too low for most traditional phono stages. I am now pretty sure about this after I put a buffer between phono e and analog input, it sounded better in terms of dynamic but some of the magic of my phono stage got lost :-(
I discussed this issue with Nick before he sadly disappeared, but of course he did not put too much effort on the analog input because not many Vinyl guys are interested in a DSP machine that has to do ADC!
So we're on the same boat! And in fact I may decided to sell my Najda boxed units for this reason. My listening is 70% vinyl and 30% digital... On the other hand a DSP has a flexibility that doesn't exist in the analog domain.... I don't know. perhaps I should look for a very good ADC machine.
On the paper the Najda has a good ADC but the problem is that input stage is designed with professional use in mind. Based on the estimate of my trusted technician its input impedance is well below 10K... which is too low for most traditional phono stages. I am now pretty sure about this after I put a buffer between phono e and analog input, it sounded better in terms of dynamic but some of the magic of my phono stage got lost :-(
I discussed this issue with Nick before he sadly disappeared, but of course he did not put too much effort on the analog input because not many Vinyl guys are interested in a DSP machine that has to do ADC!
So we're on the same boat! And in fact I may decided to sell my Najda boxed units for this reason. My listening is 70% vinyl and 30% digital... On the other hand a DSP has a flexibility that doesn't exist in the analog domain.... I don't know. perhaps I should look for a very good ADC machine.
All that Najda would be doing for you would be RIAA equalistion. I believe that you correctly identified the deficiency as the phono front end. These have their own challenges and you are right to not trust Najda to do that well. My recommendation is that you need a dedicated front end to do the signal level amplification to line level before Najda RIAA.
