advertisement


Avondale Schottky Full Wave Bridge Module.....(Bargain)

CoherentSystems said:
ust to illustrate the point Richard was asking about, I have hooked up one of the basic bench power supplies we have to the DC load and performed the same test as yesterday but using the bench supply at 5.3Vdc and taking readings @ 0/1/3 and 5 amp load as you can see the most voltage drop is around 0.4Vdc @ 5 amps.
Click to expand...

It's commonly called load regulation or output impedance.

It's easy to make regulators with very low output impedance - just apply lots of loop gain.

CoherentSystems said:
and yet keeping impedances in the happy zone
Click to expand...

Which impedances and how do you define the happy zone?
 
CoherentSystems said:
Now you have lost me jpk, which section you referring to the diodes or complete power supplies?
Click to expand...

I am not sure I understood correctly, hence I am asking. It seemed to me that the talk about large voltage drops with high loads meant the diodes only...?
 
Hello Adrian


Thanks for the reply.

There are many small little improvements that can be accumulative no question.

I designed a FBR for some audio amplifier designs I was working on about six years ago for another client, I swapped to using CREE units and these made not an inconsiderate difference, lower noise, improved dynamics along with much greater linearity to the playback, BUT they took and absolute age to fully come on song.

Which is why I build slammer circuits to really place the designs through their paces.

I have since moved on to not using diodes in FBR for a few reasons, however as a DIY prospect it's both time consuming design wise and the BOM you chaps would wince at.

In a few years when the device IC cost drops pricing will be more manageable imho.

Keep up the good up work, finding out these little nuggets is always satisfying and you chaps are good at sharing this knowledge.

ATB

Tony
 
Tony, Thanks again, my biggest shock has been copper !

Now as soon as I know a unit is using the case as signal GND, I'm ordering 1.2 mm copper plate from eBay and riveting it to the chassis then making sure where it connect to any GND points it's super low impedance. On first experimenting with this I was so taken back by the increase in bass weight and dynamics I rebuilt my modified boards into a stock chassis to make sure I wasn't miskaten

I'll give the rectifier some time before rewiring in the old and seeing what the differences are đź‘Ť at the moment I'd say I have a slight question mark over the upper mid and some transients everything else seems as good or potentially better, but that hopefully is just the running in process or me. I now keep a spreadsheet to see how many hours the components have had and how it's sounding every few days as things run in, I find it useful to refer back now and then
 
S-Man said:
It's commonly called load regulation or output impedance.

It's easy to make regulators with very low output impedance - just apply lots of loop gain.



Which impedances and how do you define the happy zone?
Click to expand...

S-man


Yes I should have used a load regulation percentage value which in fairness would have been the more engineer explanation, although not everyone on this section is that versed in such terminology I suspect

You can indeed produce an low impedance output from your regulation circuit one well used method can be by applying positive feedback compensation pathway, this is with usually the lower power output LDO's (Sub 3A usually) can provide a much greater stability right across the LDO's performance range, keeping the output voltage variation far more stable under transient demands than without this increased high loop gain circuit in play.

It will also reduce the component count as the use of a smaller tight ESR capacitor is not required. This will also improve the line & load regulation figures as well. By using a self-adjusting impedance stage placed between the error amplifier and output transistor this will allow fasting switching of the power transistor which in turn will help with the transient response of the supply. PSRR figures again will improve, by how much? this depends on implementation of the circuit and what you are really trying to achieve with it IE: what load/how often/dynamic swings etc.

On large current applications the power transistor location/board stack up/driver circuit/trace pour/ground plane location/depth/layers and connectors all play their part here.

Impedances and measurement very good question;

What would you describe as a low impedance for the power supply? in audio 600Ohms is considered low, with RF anything below 100Mhz is considered DC lol

Would you feel 377Ohms or 50 or a lower number?

Impedance matching (board traces/routing and connectors) are all in this game.

Measuring impedances, you can use a DVM (Crudely impedance being roughly 15% lower of reading shown for resistance) LCR meter, impedance analyser, curve tracer and for total impedances in a full transmission line I have two other methods.

Time Domain Reflectometry via a VNA (Vector network analyser) or high-performance scope with TDR capability with eye doctor and Virtual probing you view the complete transmission line from start to finish and with the app (lol) you can de embed each component as well as the total impedance, Very handy for board tracing faults and measuring / comformation of your prototype board in the real world.

You can also simulate various components changes to the board say an inductor value change in a filter from say 10uH to 7.3uH in real time, or a capacitor value addition etc.

Changing of terminations can be factered into the equation as well as long as you tell the scope exactly what you wish to do, have seen few interesting results over the years.

The ability can cope with transmission lines up to 40m long and not just a distance to fault finder! You can 'remove' the components singularly, it's a great tool, although it’s not a simple set up.
 
Last edited:
IWC Doppel said:
Tony, Thanks again, my biggest shock has been copper !

Now as soon as I know a unit is using the case as signal GND, I'm ordering 1.2 mm copper plate from eBay and riveting it to the chassis then making sure where it connect to any GND points it's super low impedance. On first experimenting with this I was so taken back by the increase in bass weight and dynamics I rebuilt my modified boards into a stock chassis to make sure I wasn't miskaten

I'll give the rectifier some time before rewiring in the old and seeing what the differences are đź‘Ť at the moment I'd say I have a slight question mark over the upper mid and some transients everything else seems as good or potentially better, but that hopefully is just the running in process or me. I now keep a spreadsheet to see how many hours the components have had and how it's sounding every few days as things run in, I find it useful to refer back now and then
Click to expand...
Hi Adrian

Grounding (0Vdc reference planes) are imho one of ther biggest issues within main stream audio, both from a chassis termination point and a circuit board stack up. So many audio designers seem to place it low down their list of priorities like RF.

Its not just the bass that improves, but the spatiality and flow of the music also, removing any impednace mismatching is always going to be a win here.

My own amps use 32mm customed machined bus bars made from our copper mix. Works a treat :cool:

I would suggest the golden rule here, never perform more than one chnage at a time, you may end up masking any changes initally.

The last diodes I used I ran them at 12 amps 50V into a 500W amplifier dummy load for 5 days, that worked!
 
Last edited:
jpk said:
I am not sure I understood correctly, hence I am asking. It seemed to me that the talk about large voltage drops with high loads meant the diodes only...?
Click to expand...

Why not try this for self?

I'm guessing you will have a dummy load of sorts, a suitable Tx or Variac, DVM possibly a current probe for the scope as well.

Worth a quick investigation I feel.

If you don't have a dummy load and or Virac I am happy to loan you the kit.
 
CoherentSystems said:
Why not try this for self?

I'm guessing you will have a dummy load of sorts, a suitable Tx or Variac, DVM possibly a current probe for the scope as well.

Worth a quick investigation I feel.

If you don't have a dummy load and or Virac I am happy to loan you the kit.
Click to expand...

Thanks, very kind! I will try it by myself, but just wanted to verify if I understood the talk in this thread correctly about diodes dropping several volts...
 
Okay, here goes....

The upgrades I made at the same time as fitting the Avondale FWB2 were to complete the addition of 33uf Muse ES caps to each Opamp +- at the back of the 0.1uf fitted originally, I had already done for L,R channels so now another 24 33uf caps spread across the board for all channels and effectively adding a distributed 396uf post the 317 and 337 regs Opamp supplies.

I have waited and burnt in with the odd listen to test tracks, it has now seemingly stopped chainging (possibly the Muse caps running in) and it has have about 65 hours of signal and 220 in stand by I have turned it off only to drain the caps for 20 mins then back on. So I suspect most of the burn in has happened, but not sure.

Anyway my over the last 3 days it's been burning in and I have not listened and it wasn't dramatically better when I did, a small amount more relaxed but not significantly. I am due to undertake anther upgrade so thought I should see how it compares, I had a nagging feeling it had lost drive and some upper midd mass, I was also unsure about the top end which is still a little unsettled with some hardness.

So a careful A-B between the rectifiers the original board mounted reg and the 'new' Avondale, my suspicions were correct and it was a fair amount better than I recall hearing last time (possibly more hours of running in on all recent caps, tants etc). This had masked the difference to some degree but I still felt I needed to A-B and go backwards as I was not happy with the sound.

My listening notes

Old Rectifier

More projection and better transient dynamics
Slightly warmer and tonally richer, BUT tighter and cleaner
Musically marginally better
Bass notably more mass, body and speed
More tangible, in the room and believable
Similar resolution, but slightly more depth to the Old rectifier and more forward projection
More immersive and a wider more real presentation

FWB2

Softer and less dynamic
Less mass
Some harshness and unsettled feeling
a little more recessed
Possibly more even in the lower registers, albeit less

Not sure what to make of this Les definitely has ears, I guess it's another suck it and see challenge. What is has proved to me is just how much difference the rectifier can make. Hmmmmm....
 
By the way anyone know where to buy a stock full size rectifier ? Be great to try one as it would be easy to swap out the Avondale and try a third option given how much difference it appears to make.
 
IWC Doppel said:
My listening notes

Old Rectifier

More projection and better transient dynamics
Slightly warmer and tonally richer, BUT tighter and cleaner
Musically marginally better
Bass notably more mass, body and speed
More tangible, in the room and believable
Similar resolution, but slightly more depth to the Old rectifier and more forward projection
More immersive and a wider more real presentation

FWB2

Softer and less dynamic
Less mass
Some harshness and unsettled feeling
a little more recessed
Possibly more even in the lower registers, albeit less

Not sure what to make of this Les definitely has ears, I guess it's another suck it and see challenge. What is has proved to me is just how much difference the rectifier can make. Hmmmmm....
Click to expand...
Interesting....your findings are nothing like what I have found and listening to.
 
Yes it is interesting, I do feel I gave it a good go, I may try again but feel it did have enough hours to start to come good. Have many added to the pre amp or just power amps ?
 
laverda said:
Interesting....your findings are nothing like what I have found and listening to.
Click to expand...
That's certainly not my experience at all!, i got an immediate uplift in clarity and dynamics and its seems to have improved since imo I had new supply caps a couple of months back worth doing yes but not in the same league as the rectifiers, its was a big change that was not expected.
 
I first installed two FWB2's in a HiCap PSU powering a Preamp (very nice) then in a SE400 power amp and find its an instant 'uplift' (in my system) there's no waiting for hours/days for an improvement though the smoothing caps where already up to speed some 6 months old.

Are you sure you have your listening notes round the right way...?? I only ask as I know others that I have installed the FWB2 into their kit and they said it was an immediate uplift as you describe in listening notes for your old rectifier.. sort of.
 
Alas I am 100% sure about which way round it was as I have to solder and unsolder, so it went on and off and that's the only experiment so far.

I am far from suggesting it isn't a good device in certain locations and I may try adding it back again at some point. I am keen to try a naim 'normal' item as well, the AV2 had a small board mounted items. So bizarrely the FWB2 had a head start as it was connected direct the the back of the caps with 16AWG Duelund cable

I have just added diodes around the regs and added post reg capacitance and upped the 10uf adjustment cap with another 47uf as advised and this has improved things by quite a bit as well. I am a believer in the 100 hour rule, which is 100 hours of play before concluding. So I will go back and I might experiment a little on the digital but this only feeds the digital volume, but you never know I guess
 
IWC Doppel said:
Okay, here goes....

The upgrades I made at the same time as fitting the Avondale FWB2 were to complete the addition of 33uf Muse ES caps to each Opamp +- at the back of the 0.1uf fitted originally, I had already done for L,R channels so now another 24 33uf caps spread across the board for all channels and effectively adding a distributed 396uf post the 317 and 337 regs Opamp supplies.

I have waited and burnt in with the odd listen to test tracks, it has now seemingly stopped chainging (possibly the Muse caps running in) and it has have about 65 hours of signal and 220 in stand by I have turned it off only to drain the caps for 20 mins then back on. So I suspect most of the burn in has happened, but not sure.

Anyway my over the last 3 days it's been burning in and I have not listened and it wasn't dramatically better when I did, a small amount more relaxed but not significantly. I am due to undertake anther upgrade so thought I should see how it compares, I had a nagging feeling it had lost drive and some upper midd mass, I was also unsure about the top end which is still a little unsettled with some hardness.

So a careful A-B between the rectifiers the original board mounted reg and the 'new' Avondale, my suspicions were correct and it was a fair amount better than I recall hearing last time (possibly more hours of running in on all recent caps, tants etc). This had masked the difference to some degree but I still felt I needed to A-B and go backwards as I was not happy with the sound.

My listening notes

Old Rectifier

More projection and better transient dynamics
Slightly warmer and tonally richer, BUT tighter and cleaner
Musically marginally better
Bass notably more mass, body and speed
More tangible, in the room and believable
Similar resolution, but slightly more depth to the Old rectifier and more forward projection
More immersive and a wider more real presentation

FWB2

Softer and less dynamic
Less mass
Some harshness and unsettled feeling
a little more recessed
Possibly more even in the lower registers, albeit less

Not sure what to make of this Les definitely has ears, I guess it's another suck it and see challenge. What is has proved to me is just how much difference the rectifier can make. Hmmmmm....
Click to expand...
It seems that you made quite a lot of changes as the same time as the rectifiers so how can you be sure that the changes you hear are related to the rectifiers only ?
One step at a time is the best way to judge in my experience
Alan
 
337alant said:
It seems that you made quite a lot of changes as the same time as the rectifiers so how can you be sure that the changes you hear are related to the rectifiers only ?
One step at a time is the best way to judge in my experience
Alan
Click to expand...

I agree, to confirm I let everything run in for a week then just removed the Avondale and re-connected the on-board rectifier just to see if this was indeed better or worse I was not totally happy with the sound, it had lost some energy and drive
 
You must log in or register to reply here.


advertisement


Back
Top