I'm running 1000u 6.3v here. The only one that came in handy.
It's really worth it that mod. I agree with you, increased musicality must be the right term.
Fran, has the flat layout altered the modulation of the power supply lines ? I'm considering going "flat" here, or at least putting in a horizontal ground plane full wall-2-wall in the enclosure.
This means I could make a digital section in the top and a analog one in the bottom. Just don't have allot of hight to play with. 🙄
It's really worth it that mod. I agree with you, increased musicality must be the right term.
Fran, has the flat layout altered the modulation of the power supply lines ? I'm considering going "flat" here, or at least putting in a horizontal ground plane full wall-2-wall in the enclosure.
This means I could make a digital section in the top and a analog one in the bottom. Just don't have allot of hight to play with. 🙄
I have some nice Sanyo oscons in 1500uF/6.3V that I can stick in. Thats what I'll add in.
I only ever had them laid out flat - my case is a recycled one from a video switcher from a studio. FWIW, the case is 1U I think, just about 30mm high. I had to shorten the standoffs a little, they are about 5mm high. Everything fits fine, in fact I am about to start a second one for a friend the same way.
I don't know about the noise, I never went to the bother of measuring it! If you can tell me what to do with an oscilloscope I have a 100mHz one here that I can use (not that well versed in oscillscopes!).
I also want to "turn on" the volumite and see how it works out. I want to try it directly to the power amp and see how it fares!
Fran
I only ever had them laid out flat - my case is a recycled one from a video switcher from a studio. FWIW, the case is 1U I think, just about 30mm high. I had to shorten the standoffs a little, they are about 5mm high. Everything fits fine, in fact I am about to start a second one for a friend the same way.
I don't know about the noise, I never went to the bother of measuring it! If you can tell me what to do with an oscilloscope I have a 100mHz one here that I can use (not that well versed in oscillscopes!).
I also want to "turn on" the volumite and see how it works out. I want to try it directly to the power amp and see how it fares!
Fran
I think he means the AVCC supply, rather than just the increase in capacitance. AVR300.... chime in here..
Fran
Fran
avr300 said:
Very very nice. 🙂
A word about this VREF.
It really meant to lower broadband noise and totally decouple the analog supply from the digital supplies (actually the decoupling was the main goal). It does this very effectively. 🙂 The reason the decoupling was key to me, is because its easier for the output stage to reject low freq than the 40-80-160mhz that is present on VDD. 🙂 The VREF mod simply makes the outputs have a lot less crud for the output stage to have to filter out or reject.
You need to be very careful going very large with the caps, as you will be adding inductance which can cause a tank cct to be created with C6 (not desirable in the least).
While we want to lower the corner on the noise as much as possible, anything below 100hz will be very easily canceled by the next stage as it is totally common mode to analog the output.
The is the wonderful thing about differential analog outputs. 🙂 If this DAC were single ended then you would have any AVCC noise directly super imposed on the signal. At low frequencies, this could very easily be audible. Not so with differential outputs. 🙂
Also remember that AVCC is a purely analog supply. Low impedance is actually far more critical than absolute noise.
It not feeding a clock or something where we have jitter effects to worry about.
Cheers!
Russ
Russ White said:
Define very large pls. I'm now using 470u for C1 and C2, they fits the layout better than my previous 1000u. I have some 220u here as well...
avr300 said:
Well the value is not as important as the inductance and ESR. Both should be low. Both of these usually correlates to case size. Generally the smaller, the lower the inductance.
Check the datasheet.
If you are not seeing any funky oscillations etc then your OK. 🙂
I am using 100uf Panasonic FM.
Cheers!
Russ
These are Panasonic FC 470u 16v with and impedance of 0.09ohm @ 100khz.
The data sheet doesn't mention the inductance though
The data sheet doesn't mention the inductance though
avr300 said:These are Panasonic FC 470u 16v with and impedance of 0.09ohm @ 100khz.
The data sheet doesn't mention the inductance though
Yes, often times they don't.
What you have sounds safe. 🙂
Russ White said:
Russ
Thanks for the warning. What I had done was to add 22uF smt Murata ceramic to C6 and increased Vref output cap (Sanyo OSCON 100uF + Rubycon ZA 47 uF). There is no oscillation but the key in further improvement is the 47 uF. The corner F is now < 1Hz. I may increase capacitance 50 uF at a time and listen.
In my case the feed is already from a feedback ALW regulator with pre-reg fed from the LCDPS.
Another thing, the sound of the Ivy seems sensitive to supply voltage. I have reduced this from 14.7V to 13.5V +-.
ps; The Buffalo Ivy should be laid flat.
For anyone worried about LC ringing (tank circuit) using a cap with significant ESR will damp it. Tantalums will work well. Alternatively use a resistor in series with the cap to form a snubber.
Caps like Oscons/Pana FMs have a bigger chance of ringing.
Caps like Oscons/Pana FMs have a bigger chance of ringing.
Often Mentioned; rarely found
I use a lot of OSCONS and low esr caps in power supplies and there has not been one incident of oscillations.
This type of alarm is often expressed in forums and people advised to use high esr caps which degrade PS performance. On a Tent power supply some years ago, I actually improved performance by at least an order of magnitude by throwing away the crap electrolytics and inserting OSCONS.
I use a lot of OSCONS and low esr caps in power supplies and there has not been one incident of oscillations.
This type of alarm is often expressed in forums and people advised to use high esr caps which degrade PS performance. On a Tent power supply some years ago, I actually improved performance by at least an order of magnitude by throwing away the crap electrolytics and inserting OSCONS.
Hey guys.
There is actually not much risk of a tank cct actually coming into effect on the VREF cct. The reason is, there is not much dynamic load, and it is well isolated with a high impedance. Just for kicks I added a series L (10uH) and tested, and it was still stable. 🙂 So I was probably worried about nothing. 🙂
Remember this is just a a reference, not a regulator.
The regulator (opamp) will see a very dynamic load, but it is equipped to do so. While it is deceptively simple, it is extremely effective.
Cheers!
Russ
There is actually not much risk of a tank cct actually coming into effect on the VREF cct. The reason is, there is not much dynamic load, and it is well isolated with a high impedance. Just for kicks I added a series L (10uH) and tested, and it was still stable. 🙂 So I was probably worried about nothing. 🙂
Remember this is just a a reference, not a regulator.
The regulator (opamp) will see a very dynamic load, but it is equipped to do so. While it is deceptively simple, it is extremely effective.
Cheers!
Russ
Re: Often Mentioned; rarely found
Good for you. However I think it's wise to have an understanding of the issues involved in case one gets into trouble, hence why I mentioned it.
I too have used Oscons many times without problems, although I certainly haven't put my scope on every power supply I've built.
fmak said:
Good for you. However I think it's wise to have an understanding of the issues involved in case one gets into trouble, hence why I mentioned it.
I too have used Oscons many times without problems, although I certainly haven't put my scope on every power supply I've built.
I have the 1500uF in place, voltage output is ok and I have yet to listen to it now - I'll report on that later.
Another problem though: I added in the volumite tonight, connected SDA, SCL and GND from the buffalo board to the volumite and connected VCC (volumite board) to VD of the buffalo. Result was the automute LED stayed on all the time. Disconnect voltage supply to the volumite and it locks again no problem. I double checked for continuity of all these connections and they are ok. Is there a jumper or anything I need to set on the buffalo for it to work?
Any ideas? I had a look on the site and I couldn't see a manual - what have I done wrong?!
Fran
Another problem though: I added in the volumite tonight, connected SDA, SCL and GND from the buffalo board to the volumite and connected VCC (volumite board) to VD of the buffalo. Result was the automute LED stayed on all the time. Disconnect voltage supply to the volumite and it locks again no problem. I double checked for continuity of all these connections and they are ok. Is there a jumper or anything I need to set on the buffalo for it to work?
Any ideas? I had a look on the site and I couldn't see a manual - what have I done wrong?!
Fran
woodturner-fran said:
Hi Fran,
I sent a manual, but I guess its not up yet.
Did you use the VREG(IC2) on the Volumite?
If you did then do not use VDD(3.3V from the header) from the buffalo, but use the VD supply (5-8V or so).
Cheers!
Riss
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