Hello steve.
Good to hear that it's working out for youIt would be interessting to see the impedance curve for the vitavox driver. I just tried a google search without any luck, do you have a link or something......?
Afraid not. There are various SPL plots of the new diaphragms that Mike at Vitavox is supplying. They have quite a SPL bulge at 1.5KHz - use of a 3uF cap tames it as if by magic. The tone and dynamic ability of these drivers when in top nick is just stunning. Surpasses the earlier clear plastic surround diaphragm and the original ali ones. I've had the good fortune to listen to all 3 types.
Yes use it a lot. Technics SP-10 deck with Fidelity Research DR64s tonerm and Ortofon SPU Silver Meister cartridge. Najda does a good job of preserving the sound of the source and with good SQ and dynamics nMO.
PSU is slowly coming together
In the picture you se from left, 2 x B+,4 x 12v filament, 3 x 5v prereg followed by 3 "Placids",
(for the buffalo dacs) 1 x 5v prereg that will supply twoTI tps7a4700evm regulators (one for the
usb reciver and one for Najda 5v).After that there is a +/- 15v placid HD bipolar for the IVY buffer and
+/- 12 for Najda .
In the picture you se from left, 2 x B+,4 x 12v filament, 3 x 5v prereg followed by 3 "Placids",
(for the buffalo dacs) 1 x 5v prereg that will supply twoTI tps7a4700evm regulators (one for the
usb reciver and one for Najda 5v).After that there is a +/- 15v placid HD bipolar for the IVY buffer and
+/- 12 for Najda .
So are you feeding the highs fullrange time aligned via najda? And filtering via passives? Or have I misunderstood?
PSU is slowly coming together
You´ll be needing a big box!
Or maybe you plan to put the PSU's in a separate one?
I tried replacing all the opamps with OPA2132. I meant to run full range on two outputs and compare by switching between the two using a preamp as this would be a very good means to compare, but I didn't have a lot of time at the weekend and ended up switching them all and only had a brief listen.
I'd say the bass seems more powerful with OPA2132 but the top end seems to lose a little sparkle compared to the supplied LM833. Imaging also seems slightly sharper although I thought it was still good with the original opamps.
When running as a proper crossover there is obviously potential to match the opamp to the frequency you are supplying to get the ultimate combination.
On another matter, I have an issue with the overall output level being quite low. I am often listening at full volume 0dB and would like to get more output. Is this something others are experiencing?
I'm also getting a lot of clipping, even with reduced levels for inputs, is this also the same for others? So, I'd really like to add some gain to input and output to compensate for low overall volume level but am unable to due to exceeding the thresholds resulting in a lot of blinking LEDs and nasty noises coming out.
Overall though, I'm very pleased with the sound coming from Najda as supplied.
Najda by itself need about 350 mA on the 5V rail, 100 mA on the -12V and 200 mA on the +12V. These are conservative values.
Jean Claude
From the manual:
5V @1A
+12V @ 1A
-12V @0.3A
I think there is some additional current in these figures to allow for feeding of other units from the expansion ports, Nick I'm sure could confirm.
The 8 channel volume control is at the end of the chain and is able to output as much as 6V so it's just a question of software programing
Concerning the input, there is a limitation of 1V RMS max due to the chip involved so the only way to increase the input margin is to add an attenuation on inputs or like I'm currently doing with symetrical input with a -6dB attenuation.
With digital xover, you have so much flexibility that it is very easy to touch the "limits" and unfortunately clipping means 100% distortion. So great care has to be taken when applying corrections...
Jean Claude
The values I gave is what I measured on my Najda board, but by no way you will ever need 1 A on the +12V side. I think that taking into account future expansions 1A/5V, 0,5A/+12V and 0.3A/-12V will keep you on the safe side. Of course having a power supply able to deliver much more power is not a problem
Jean Claude
Thanks. For the time being I am trying to keep at 1Amp for 5V and 300-400 mAmp for 12V lines.
The DAC chip used is pretty sensitive it seems ,to voltages above 5.5.Can I use a Zener to prevent voltage from going above 5.1V. Will that introduce noise to the pwerline if it is not switching ( voltage stays at or below 5.1V)
http://www.onsemi.com/pub_link/Collateral/ESD7951S-D.PDF
http://www.comchiptech.com/cms/UserFiles/CPDU-Series-RevD.pdf
The DAC chip used is pretty sensitive it seems ,to voltages above 5.5.Can I use a Zener to prevent voltage from going above 5.1V. Will that introduce noise to the pwerline if it is not switching ( voltage stays at or below 5.1V)
http://www.onsemi.com/pub_link/Collateral/ESD7951S-D.PDF
http://www.comchiptech.com/cms/UserFiles/CPDU-Series-RevD.pdf
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That is correct for the mid driver and upper mid. The mid bass and tapped horns are Najda X/O'd. All time aligned in Najda.
PSU is slowly coming together
In the picture you se from left, 2 x B+,4 x 12v filament, 3 x 5v prereg followed by 3 "Placids",
(for the buffalo dacs) 1 x 5v prereg that will supply twoTI tps7a4700evm regulators (one for the
usb reciver and one for Najda 5v).After that there is a +/- 15v placid HD bipolar for the IVY buffer and
+/- 12 for Najda .
That's a lot of PSU you have here! That tiny red board in the upper right corner, is that Najda?
Have you tried boosting the nominal output level? In the menu, Settings -> Board Configuration (Najda must be connected). By default, output level is 1 Vrms, you can increase it up to 6 Vrms.
As Jean-Claude said, digital gain values are generally going to be negative. This is because the processing needs some headroom for EQs in particular, but also for cross-over filters that present a bit of overshoot. You can compensate further with analogue gains as explained above.
The manual is coming, there's a paragraph on adjusting gains.
Glad to hear Hugo, thank you!
Yes, indeed. You can cut down these figures by 2 if you don't intend to draw much current from the expansion ports.
I wouldn't worry too much if you can make sure that you've set properly your regulator to output 5V. A meter will tell you (before you connect the power supplies to Najda).