Rank: Member
Groups: Member
Joined: 8/17/2010(UTC)
Posts: 368
Location: australia
Thanks: 8 times
Was thanked: 3 time(s) in 3 post(s)
|
Originally Posted by: luisbock  Hi
I dont have a scope. Can the ripple problem be present with Placid HD, stock trannies and Buffalo 3 Standard build? Are there any diferent issues in avr300 setup to the present Buffalo 3 (non SE) build advice?
Regards Yes, see post 46,47 & 48. I don't have a scope either, I'm just modding on trust :) Edited by user Monday, April 22, 2013 11:13:52 AM(UTC)
| Reason: Not specified
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 6/17/2008(UTC) Posts: 921  Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
|
Originally Posted by: fred_com Hi guys,
one note about this mod - when modding negative side of Placid HD BP polarities of electrolytic caps should be reversed (C2, C3 and the new one).
If polarity is not reversed - the negative side voltage will sag.
I don't know how this works, but I'm sure Russ will clarify this :)
Thanks,
Fedor Always pay attention to polarity by using your DMM. But you're 100% right.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 10/8/2009(UTC)
Posts: 1
Location: Norway
|
Thanks to avr300, Russ and all you other guys for posting and making the mod possible. Here's my "anti-ripple-mod" of the Placid HD 1.0, using slightly different pads on the PCB to get room for it all (TP_GND2 is handy) - in case someone might find it useful.  Caps are 1xNichicon FG 1000uF/35V and 2xElna Silmic 100uF/35V. Next up is Placid HD BP 1.0. Edited by user Wednesday, April 24, 2013 6:43:59 AM(UTC)
| Reason: Not specified
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 4/9/2011(UTC)
Posts: 37
Location: Lisbon
Thanks: 1 times
|
Originally Posted by: DQ828 Originally Posted by: luisbock Hi
I dont have a scope. Can the ripple problem be present with Placid HD, stock trannies and Buffalo 3 Standard build? Are there any diferent issues in avr300 setup to the present Buffalo 3 (non SE) build advice?
Regards Yes, see post 46,47 & 48. I don't have a scope either, I'm just modding on trust :) Thanks DQ828 Does it mean we all have to do this mod for a clean PS? Regards
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN
Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
|
I have already stated - no you do not. It is completely optional, and in fact there are cases where it may not be desirable.
All this mod does is give better PSRR at the expense of a slower start up time because of the large time constant.
If you size the transformer and the reservoir caps appropriately for your load, the ripple will not be large enough to bother with.
The mod is completely optional - that said I think its a good one for many cases (and that's why I showed how to do it).
As with anything there is a trade off, that is the slow ramp up time, which in some applications will not be desirable.
As with anything DIY - it just depends on what is important in your particular case. :)
Also it just shows there is almost always more than one solution to any given challenge.
Cheers!
Russ
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 6/17/2008(UTC) Posts: 921 Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
|
Who's all ? ;-) It's completely optional, although I recommend it. Regarding the placement of the C2-C3 your can just swap the onboard 220nF for the upgraded once, no need to place them under the board. Oh yes, I upgraded the main caps as well. Remember, it's DIY. ;-) avr300 attached the following image(s):  IMG_6098.JPG (90kb) downloaded 193 time(s).You cannot view/download attachments. Try to login or register.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 3/8/2011(UTC)
Posts: 136
Location: Norway
Was thanked: 2 time(s) in 2 post(s)
|
Are you willing to share the specs on your upgraded caps avr300 ?
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 3/8/2011(UTC)
Posts: 136
Location: Norway
Was thanked: 2 time(s) in 2 post(s)
|
The four small ones in front of the 33000uf.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 6/17/2008(UTC) Posts: 921 Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
|
Yes certainly, my pleasure. Panasonic FM 470u, 16v. You know, what ever comes handy (at the end of your fingertips) one uses. avr300 attached the following image(s): IMG_6093.JPG (89kb) downloaded 104 time(s).You cannot view/download attachments. Try to login or register.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 2/1/2012(UTC)
Posts: 332
Location: The Netherlands
Thanks: 4 times
Was thanked: 18 time(s) in 18 post(s)
|
How much longer does it take before the desired voltage is reached? Is there a way of calculating it. Maybe the same way as when calutaling the RC time constant of a resistor–capacitor circuit?, I'm asking this, because I'm worried when I do the mod the time it takes to start the DAC becomes a bit too long for my I2C controller. My controller starts first and swithes a relay to power the DAC. It waits for 50 ms after the relay is switched, than it starts programming the DAC. I'm not sure what will happen if the start time is longer as 50ms . I can always increase the delay of course, but I still need to now by how much. I don't want full volume blasting through my speakers when the delay is too long  I'm also wondering how useful this mod is for the Buffalo, because it already has low noise regs for all important parts of the chip. I my opinion the mod has more influence on the analoge parts, such as the IV stage. Not trying to say here that the mod is not useful for the Bufallo, but just sharing my thoughts :) |
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 6/17/2008(UTC) Posts: 921 Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
|
I'll fancy - "the less noise you put in the less noise you'll get out"
But it up to you.
Yes, you could calculate the start up time, or you can measure it. Perhaps using 470u instead of 220n is "going over the top" - but that was what I had at time of presence.
With the components I use it's roughly 2 sec.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 2/1/2012(UTC)
Posts: 332
Location: The Netherlands
Thanks: 4 times
Was thanked: 18 time(s) in 18 post(s)
|
Originally Posted by: avr300 But it up to you.
I'm very tempted. I think that I will give it a try soon, but I will use some smaller values instead to keep the delay as short as possible. :) Edited by user Monday, April 29, 2013 9:00:15 PM(UTC)
| Reason: Not specified |
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 3/8/2011(UTC)
Posts: 136
Location: Norway
Was thanked: 2 time(s) in 2 post(s)
|
avr300 ; is it just to go for Phanasonic 470u without change anything else ? Something I will need to adjust?
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 4/9/2011(UTC)
Posts: 37
Location: Lisbon
Thanks: 1 times
|
Originally Posted by: Russ White I have already stated - no you do not. It is completely optional, and in fact there are cases where it may not be desirable.
All this mod does is give better PSRR at the expense of a slower start up time because of the large time constant.
If you size the transformer and the reservoir caps appropriately for your load, the ripple will not be large enough to bother with.
The mod is completely optional - that said I think its a good one for many cases (and that's why I showed how to do it).
As with anything there is a trade off, that is the slow ramp up time, which in some applications will not be desirable.
As with anything DIY - it just depends on what is important in your particular case. :)
Also it just shows there is almost always more than one solution to any given challenge.
Cheers!
Russ Thank you Russ, you made the issue cristal clear. I am just looking for wise solutions, just got a little confused with the thread direction. Best regards
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 6/17/2008(UTC) Posts: 921 Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
|
Originally Posted by: musicman avr300 ; is it just to go for Phanasonic 470u without change anything else ? Something I will need to adjust?
Don't forget the decoupling of the error amplifier, the resistor / cap mod mentioned earlier in this threat. It's at least important as the C2/C3 upgrade. Always check the output voltage and shunt current after a mod.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 3/8/2011(UTC)
Posts: 136
Location: Norway
Was thanked: 2 time(s) in 2 post(s)
|
|
|
|
|
|
|
Rank: Advanced Member
Groups: Member
Joined: 11/3/2010(UTC)
Posts: 52
Location: Belgorod, Russia
Thanks: 6 times
Was thanked: 1 time(s) in 1 post(s)
|
Hi guys,
After applying this mod everything was fine, but then I've decided to upgrade filter caps as well - to 22000uF, and now I have a problem with Placid HD BP which is powering a Legato 3 with buffers - sometimes on turn on the output voltage is 1.62v instead of 15v and QN1 gets really hot. After several power cycles it starts normally.
Mod config - C2, C3 - 47uF, additional cap is 220uF, resistor is 220 Ohm.
Could it be because C2 and C3 capacitance is too high? Or is it strictly because of beefier filter caps? But others seem to use even more capacitance with no ill effects.
P.S. Large capacitance on C2, C3 is actually not desired (as Russ already said) for some controllers, and I've learned it myself, when powering certain USB-I2S controller based on XMOS chip.
P.P.S. Btw, I've measured output with oscilloscope with just larger filter caps, but without this mod - ripple was still there.
Thanks,
Fedor
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 6/17/2008(UTC) Posts: 921 Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
|
Here I have seen the same. Not only after upgrading the main caps from 10kuf to 33kuf but also before with the stock caps.
Try beefing up the tranny. With the 30VA stock the the powerup procedure was wobbly. Now, with a 120VA tranny, the _CLICK_ from the Legato mute relay is really authoritive, starts up 10 of 10 times. And the sound is much more present.
No matter what others think - the 30VA tranny seems to be a bottleneck.
Good luck.
|
|
|
|
|
|
Rank: Advanced Member
Groups: Member
Joined: 11/3/2010(UTC)
Posts: 52
Location: Belgorod, Russia
Thanks: 6 times
Was thanked: 1 time(s) in 1 post(s)
|
Hi avr,
thanks for your quick reply.
Looks like new trafo is the way to go :)
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN
Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
|
Or just use two, one for each rail (with it's secondaries in parallel) :)
|
|
|
|
|
|
Forum Jump
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.
