Hotrodding the UCD modules

[Portlandmike]

Hi Mauricio,

Good luck with the coupling caps, its good that your going to be trying out some different types too

I realize you use the UCD400, ignore my rambling😀

It sounds crazy but since fitting the AD8620 I've never enjoyed the sound as much as I did, yes the AD8620 is better than the standard NE5532 in a lot of ways but since fitting this chip its added a sort of colouration,signature which I'm finding hard to get used too so its something I'm going to work on.

t,

Maybe this will make it better:
I couldn't help but look at your regulator you posted pictures on.

Are you using it?

Next time you spin one, run it by me, I'll give you some free advice. Here is just a bit, guessing at your design goals:

1) I see two bridges, which makes me think you have a split winding transformer. If so, you need not do a positive and negative regulator, but just do two positives, or two negatives, which ever one you like best. Make your two regulated "12V" or whatever, then connect the them in series.

This has the added advantage of minimal power ground currents flowing in your audio ground.

2) You use a long trace to connect to the first bypass caps to the strip ground. This will double the inductance of the cap, and almost prevents them from doing there potential at HF.

If you just forget about ground until the end, it will help you in layout. If you must do a center tap, then its only a bit different, but you need to have more meat in your cap ground connections.


I always treat caps as 4 ports. That is, the inputs come in one side, and the outputs go out the other side. This gets you the maximum performance. You want the pad for the cap smallish, and bring the input trace in (it can be small, no real need for meat this way.) one side. Bring your output trace out the other. This applies for both pins if you have split windings. What this does is force the electrons to pass right by the pins, witch no way around. The benifits are clearly measurable in the right conditions. Its very similar to the Jensen or Tcap 4 pole stategy, only its board level. The idea is to use parasitics to your advantage.

I'm sure what you have will work okay. If you decide to spin another one.... I'll help you if you want.

Best Regards,

Mike

 

[LTK]

t,

Maybe this will make it better:
I couldn't help but look at your regulator you posted pictures on.

Are you using it?

Next time you spin one, run it by me, I'll give you some free advice. Here is just a bit, guessing at your design goals:

1) I see two bridges, which makes me think you have a split winding transformer. If so, you need not do a positive and negative regulator, but just do two positives, or two negatives, which ever one you like best. Make your two regulated "12V" or whatever, then connect the them in series.

This has the added advantage of minimal power ground currents flowing in your audio ground.

2) You use a long trace to connect to the first bypass caps to the strip ground. This will double the inductance of the cap, and almost prevents them from doing there potential at HF.

If you just forget about ground until the end, it will help you in layout. If you must do a center tap, then its only a bit different, but you need to have more meat in your cap ground connections.


I always treat caps as 4 ports. That is, the inputs come in one side, and the outputs go out the other side. This gets you the maximum performance. You want the pad for the cap smallish, and bring the input trace in (it can be small, no real need for meat this way.) one side. Bring your output trace out the other. This applies for both pins if you have split windings. What this does is force the electrons to pass right by the pins, witch no way around. The benifits are clearly measurable in the right conditions. Its very similar to the Jensen or Tcap 4 pole stategy, only its board level. The idea is to use parasitics to your advantage.

I'm sure what you have will work okay. If you decide to spin another one.... I'll help you if you want.

Best Regards,

Mike

Thanks for the advice Mike although this regulator was not actually my design or layout, I simply etched it from a pdf to try out😉 I have not used it either after looking at the output on a scope, its probably more noisey than the standard onboard supply😀 I'm still using the UCD's onboard +/- supply for the op-amps.
When I do decide to use offboard regs I have a pair of +/- ALW super regs which will be used instead, infact as soon as I can find a neat way to fit the regs without having to alter the UCD board too much I'll fit them.
I didn't mean to sound like I thought the UCD180 was bad, its far from it🙂 its just that I have several other amps here too and since building a new pre-amp for the AvondaleNCC200 its performance has dramatically improved, infact the bass and clarity is fantastic, I'm just comparing the UCD against what I have.
Thanks again for your advice though, it is always appreciated🙂 Only pcb software I have is Sprint-layout although to be honest I've not drawn anything out on it yet apart from a couple of dac designs

ATB!

 

[maxlorenz]

Thanks t. and Mike for the replies.

I feel bad for you and the noise.

Yes. Me too ...and tired sometimes.

I can't help but wonder if your getting aliasing of high frequency hash from your Dac. This may be stupid, but I've read a few of your comments on this and thought I'd give you some free advice.

Well, I've thought many possibilities and tried to rule out some but soldering and desoldering things again and again is tiring and dangerous.
The last time the system sounded good was when nonos had single BG-NX at output. I'll return back to that.
I have even not tried my M-audio superDAC latelly because I wanted to play with CDPRO->nonos.
It's the bad thing of being at the lowest part of the learning curve!
I use to put thick wood bases on gear. Maybe the wood is not completelly dry and carry some currents. I'll remove them.

But I'm learning a lot with this HF noise! 😀

First off, if its on ground, your kind of in trouble, but lets hope its not that. Have you tried just doing a serious low pass RC. Something like 100ohms and some big cap to put a pole at 20kHz.

I can try the filter if I continue to have this trouble.
Maybe I did not catch you here. You mean a filter for the DAC output or filter the amp's ground?

Many thanks for your support and interest.
Mauricio

PS: I'm trying to contact a local EE to parasyte from his knowledge 😀

 

[Portlandmike]

Thanks t. and Mike for the replies.

I can try the filter if I continue to have this trouble.
Maybe I did not catch you here. You mean a filter for the DAC output or filter the amp's ground?

I mean to filter the DAC output. I recall Brono mentioning that in on implementation that he liked, SACD's gave it grief. I can't help but wonder if your hearing that problem, down converting of the noise by the UcD switching frequency.
Adding a filter should reduce the problem. Its not a solution as much as a hint to the root.

I suspect its grounding. A picture is worth a thousand words.
If you can send a picture of your stuff, maybe I can see it.

Mike

 

[maxlorenz]

Dear Mike:

I recall nonos with TDA1543 are already -3dB at 20Khz.
Can it be aliasing problems with such a low F?
Could they send supersonic noise?

I will have to disconnect the DAC's fan

I suspect its grounding.

Yeah, me too.
It's funny, when I first build the UCD180 the HF were astonishly natural and relaxed. After many changes and mods to other equipment and who knows what else, here I am...

Before sending a diagram (no wasting money on cameras)
I'll try to find the time to check the modules decoupling...

Best wishes
Mauricio

 

[Portlandmike]

Dear Mike:

I recall nonos with TDA1543 are already -3dB at 20Khz.
Can it be aliasing problems with such a low F?
Could they send supersonic noise?

I will have to disconnect the DAC's fan



Yeah, me too.
It's funny, when I first build the UCD180 the HF were astonishly natural and relaxed. After many changes and mods to other equipment and who knows what else, here I am...

Before sending a diagram (no wasting money on cameras)
I'll try to find the time to check the modules decoupling...

Best wishes
Mauricio

Mauricio,

The question for aliasing is not where is it 3dB down, its potentially much more sensistive than that. Assuming its switching at 400kHz, the question is how far down is it at 400kHz.
If its 3dB down at 20k, and its a single pole, 6dB per octave, then your only down by 26dB at the switching frequency.

email me if you want to send it direct. Layout is a gift I have.

Best regards,

Mike

 

[LTK]

Be careful Mike mate, you'll be getting a flood of E-mails from us asking for advice if your offering it for free😉

It would we nice if we could have a thread with some idea's for good pcb layouts for the UCD's supply, reg supply etc🙂

 

[Portlandmike]

Be careful Mike mate, you'll be getting a flood of E-mails from us asking for advice if your offering it for free😉

It would we nice if we could have a thread with some idea's for good pcb layouts for the UCD's supply, reg supply etc🙂

I make the offer only to special people 🙂
those who have helped me in one way or another are prime canadates. Maybe I'm selfish!

A special thread would be good. Frankly, I"m toying with lots of pics of my next project. We'll see.

There are lots of misconceptions and chasing of the wrong things, superstitions....

I have yet to actually get my UcD to the Lab for testing. I've got 7 on order, so there can be some detailed playing over the next few months. Problem is I've got a big paying project comming down in the next month, so that could crimp it.

Best Regards,

Mike

 

[LTK]

I make the offer only to special people 🙂
those who have helped me in one way or another are prime canadates. Maybe I'm selfish!

A special thread would be good. Frankly, I"m toying with lots of pics of my next project. We'll see.

There are lots of misconceptions and chasing of the wrong things, superstitions....

I have yet to actually get my UcD to the Lab for testing. I've got 7 on order, so there can be some detailed playing over the next few months. Problem is I've got a big paying project comming down in the next month, so that could crimp it.

Best Regards,

Mike

To be honest Mike I wouldn't call it Selfish, I do understand what you mean,I'd gladly help anybody I can though on here, I've made some good friends on this site and I've also been given some very helpful advice in the past which has been appreciated🙂

It would be nice to have a couple or single diy pcbs with excellent HT and LT supplys for these modules, I want to try these ALW super regs I have spare but having four reg boards plus more boards for the recitification etc is going to look a mess and make any tweaking a bit more fiddly

We will look forward to reading your results with the UCD's when you get the time🙂
Theres probably still a lot more things we can try out with these modules

 

[maxlorenz]

Oh! Mike...

I make the offer only to special people

Me too!

email me if you want to send it direct. Layout is a gift I have.

ASAP!

Can you answer in spanish? 😀



Ethernal gratitude to my fellow DIYers...
Mauricio

 

[classd4sure]

Re: New output filter cap concept

Chris,

I have yet to cut the single wire that connects my power ground to the chassis. I did connect signal ground to the RCA input ground along with -IN.

My reasoning was, nothing is really connected to it, and sure seems like it should be tied to something.

Then I thought about the heat sink, maybe being connected.

I guess from what you've said before you'd float the chassis, is that correct?

Mike

p.s. Now you've got me thinking about all those spring loaded speaker connectors in my JBL's.

Uh huh, here's my reasoning, the only way to ensure there's no current flow in a wire is to have no wire 🙂 Float the sucker~! Do whatever you have to so you can float it and get away with it with no ground loops. I had noticed you'd not done that, I found it extremely worthwhile when it comes to imagine and detail.

If you look at the module you see the speaker ground and signal ground are common, connect them both to both to chassis and you inevitably have a ground loop, so comes the question, are you then referencing the signal ground to the power ground, or the power ground to the signal ground? Best you can do if you want to use it is minimize the loop area, but that can never be ideal. If you float the cap common point from the chassis it allows you to tie the signal ground to the source ground at the chassis, and ensures the output current can't interfere with that ultra clean source of reference, furthermore you without doubt referenced the power ground to signal ground! You should hear noticeable difference.

I've been bouncing around an idea for the output filter cap.

I suspect that as the cap gets voltage impressed on it, it tightens up.
The problem is that at low signal levels, its not tight as its only the winding tension and no electrostatic forces, which will be quite high.

What if

You replaced the single output filter cap with two twice as big, and put them in series (or four 680nF for in series prallel.)
At the series node, bias them with a large resistor to one of the supply rails.

That would impress lots of volts on them, and at 1 Meg, it would have little affect on the output (although you could filter this if you were concerned.

I'd be you'd hear the difference. The JBL K2's do something like this in the passive crossover, and its been found to give positive results.

Might make otherwise sloppy vague caps better, and good caps better yet!

Voltage rating would need to be at least 50% greater though, as 1/2 Vout will be impressed on top of the bais voltage.

Let me know what you think?

Wish I had some output filter caps to play with.

Mike

This seems interesting in theory but I have my doubts it would be at all practical. Even stronger reservations about the series// version.

The main points are all the added loop area putting EMI through the roof. Also it seems the vast majority of those volts you want to impress on them are being dropped over the 1Meg resistor. It just can't be that effective. I've heard and seen horry stories from JBL, I wouldn't be quick to follow their lead.

It seems to me a better practical solution would be to select a cap that's less microphonic than a stacked film, perhaps a rolled film/foil? Squashed if it has to be.

Dear all:
Yesterday I found the time to swap the normal PS (znuberrized )recifier diode bridge, for my Ixis, 68A, slow recovery bridge we talked about previously, on my UCD400 mono's:

http://www.partsconnexion.com/catalog/semiconductors.html

I strongly recommend these bridges 🙂
Maybe you're familiar with the experience of hearing everything like 3db more louder after a mod? Well that's what I heard and I didn't expect it. Also a significant increase in bass punch and quality, more "analog" I would say. 😎
The presentation is more relaxed. My HF problem now feels as a "dirth" on top.
I listened to Brukner's 4th symphony, "romantic", and the previous thought about Brukner's music being punchy on midrange and highs but lacking bass was totally wrong from my part. It is good to hear those double-basses rrrrumbling 😀
Also, the diodes allowed for a more relaxed (yet very dynamic) listening to this stressing music 😉

I used the horrid faston to connect them. Chris, did you solder it?

Dear Mike:
SuperE-cap is a pair of non polar BG's in "anti-parallel" configuration. The caps have a long lead an a shorter one plus N.P.N on one side only. One of those sides is the beginning of the foil, as I understood. By connecting in anti-parallel manner the foil "spin sense" is opposite. They claim that this way ESL is canceled and ESR lowers at UHF

http://www.acoustic-dimension.com/blackgate/techEcap.htm
http://www.blackgate.jp/ebg6.htm

I don't know if they do everything they claim but to my ears they sure do something!
I've tried on low V power supplies as decoupling with variable success, probably due to my inexperience. 🙁

If someday I understand what the filter cap does, I could dare to change it 😀

Cheers everybody!
Mauricio

Yeah they're nice rectifiers alright. Worth every penny, cleans things right up and sure lets it breath!

You better believe I soldered it. Would not have used a fast on there... I hope you crimped it a little if you did. Later on when I slap it all together in a finalized version I'll trim the leads to about half what they are now, solder the wire on and put some heatshrink over it. I'm using Cardas quad eutectic solder btw, very strong joints.

I'm thinking about taking the 680nf Auricap out of the filter for my UCD180 and fitting something like a Evox MMK until I can source some other films to try.
The Auricap is ok but its made the sound really polite and smooth, they have been in now over two weeks, infact it makes my tube amp sound agressive😀

I should have the collection of decoupling caps to try soon, for the time being I'm going back to my AD815 pre and AvondaleNCC200🙂

Good luck with the caps. I'm satisfied with mine for now....... I have no choice 🙁 @#%@*$# solder pads.

I can once again recommend my filter cap, veeeery happy with it. Precision from hell.

 

[LTK]

Re: Re: New output filter cap concept

Good luck with the caps. I'm satisfied with mine for now....... I have no choice 🙁 @#%@*$# solder pads.

I can once again recommend my filter cap, veeeery happy with it. Precision from hell.

I know what you mean regarding the solder pads Chris, mine are also starting to look a bit scabby

I'm very pleased for you that your happy, thats great!
I'm going to take the Auricaps out, I don't like their signature to be honest, I also just tried some now well burnt in Auricaps on my dacs output they lasted a couple of hours until I took them out and refitted the Multicap RTX's.
I would love to try the ones you use Chris but I'm struggling to get them, unfortunately I'm limited to places like Farnell or RS in the UK

 

[classd4sure]

Scabby isn't too bad, I had one lift. Still works though 🙄

I really could be more happy with it, but I have my bass and I have my holographic air back...... have to draw the line somewhere. There's still more I can play with though. All in good time. It could be a bit more natural sounding... but it's alllll money right? I guess the truth is I'm happy enough considering I lost a solder pad. No more messing with caps on these suckers. Anyway, I find it extremely easy to listen to, non tiring, musical, and entirely enjoyable. I'll take that over "oh no, it's not working anymore" anyday. Not to mention I'm hearing alllllllll kinds of things in old songs I'd never heard before. Hard to believe it can still can better.. I've been saying that since I got them though.

Just don't fall for that 45$ novelty cap. If I could send you a pair like mine I would.

Cheers

 

[steve.mcqueen]

comparisions

Hi Dears,

I am following all this messages, but I can't see too much about sound quality. We should have some conclusion after almost one year fo trials and experiences.

I would be very nice if we state the setup of our UCDs and all the other equipment used and make statement like: "the highs where not harsh, detailed and liquid, the bass... etc".

My experience is with two UCD180, a R-core trafo (suggested in another post in the past), I used 27-0-27V 600Va, with bridge rectifiers and 10,000uF Rifa-Evox caps on each side (expensive but worth of their price). The psu gives me something like 37Vdc (well below inside the suggested range 30-45 Vdc). I believe that lower voltage is always better, at least it does not stress components too much, and this is expecially wellcomen when caps are not rated for high voltages.

I do not use any decoupling caps or other strange things. In my opinion if you did not design the entire circuit than you should use the most simple PSU. Other wise you risk to "over-filter" some bit of the spectra. Anyway, I belive in "simplicity"

Our test is with Marantz CD17 massively modified, Linn Sondek LP12 with SME 3009 arm and Blue Point Special, a DIY tube based pre amp and DIY 3-way sealed speakers with 12",10",1" drivers from seasl and scan-speak.

As we started to play the amp it sounded natural, the highs are fresh, liquid, the bass is incredibly fast but with maybe less body if comparaed with solid state horses. I wouldn't say that this is wrong because sometime solid states produce innaturally huge basses.

Speakers have very large woofer who is able to play 27Hz flat in room, and I don't think I miss any bass. The stage is very good and the separation between instruments is incredibly good. With Records works even better since the highs become more liquid.

I think that the psu is very important, for example I changed the caps with lower quality stuffs and the sound deteriorated expecially in the basses. I also think that the trafo is imporatant, I always try to avoid toroidal expecially if they are not of the best quality.

The problem is that in general toroidals are not as dynamic as other topologies (C-core, E, R, etc). I experienced this in many cases. This affects basses, because when the music concentartes on a dynamic bass line, this requires high currents in extremely small time intervals so that trafo and caps are required to work fast, very fast. I am not an epxert but I think toroidals are not able to do that, I don't know why.


I found also very important to have extreme cure of shielding. I used a separate box for the tarfo becuase in the beginning I had probles at high frequancies. I had some noise which now has gone. Both boxes are shiled and earthed.

Bye and let me know your experiences,
Steve

 

[Portlandmike]

Re: comparisions

Uh huh, here's my reasoning, the only way to ensure there's no current flow in a wire is to have no wire 🙂 Float the sucker~! Do whatever you have to so you can float it and get away with it with no ground loops. I had noticed you'd not done that, I found it extremely worthwhile when it comes to imagine and detail.

If you look at the module you see the speaker ground and signal ground are common, connect them both to both to chassis and you inevitably have a ground loop, so comes the question, are you then referencing the signal ground to the power ground, or the power ground to the signal ground? Best you can do if you want to use it is minimize the loop area, but that can never be ideal. If you float the cap common point from the chassis it allows you to tie the signal ground to the source ground at the chassis, and ensures the output current can't interfere with that ultra clean source of reference, furthermore you without doubt referenced the power ground to signal ground! You should hear noticeable difference.

Chris, I understand you concerns over ground loops, but my speaker connections and the inputs are not connected to chassis.
There is only one wire to chassis, and nothing else makes contact.
Well almost nothing. I wanted to try it so I cut the wimpy little wire. The amp went dead. I forgot the other wimpy wire I connected to it that pulls down shut down. Oh well. I do hear you on the potential for things like magnetic induced stuff, so the day I bring my soldering iron home, I'll try it.

This seems interesting in theory but I have my doubts it would be at all practical. Even stronger reservations about the series// version.

The main points are all the added loop area putting EMI through the roof. Also it seems the vast majority of those volts you want to impress on them are being dropped over the 1Meg resistor. It just can't be that effective. I've heard and seen horry stories from JBL, I wouldn't be quick to follow their lead.

It seems to me a better practical solution would be to select a cap that's less microphonic than a stacked film, perhaps a rolled film/foil? Squashed if it has to be.

Chris, The loop area may increase a bit, but I'm not worried about that so much. When a cap and resistor are in series, all the volts end up on the cap, not the resistor. There will be a small AC component on the resistor, but nothing much.
It will be interesting anyways. I"m going to study the board carefully when I get my new ones. Depending on layout, there might be other good options.

Yeah they're nice rectifiers alright. Worth every penny, cleans things right up and sure lets it breath!

You better believe I soldered it. Would not have used a fast on there... I hope you crimped it a little if you did. Later on when I slap it all together in a finalized version I'll trim the leads to about half what they are now, solder the wire on and put some heatshrink over it. I'm using Cardas quad eutectic solder btw, very strong joints.



Good luck with the caps. I'm satisfied with mine for now....... I have no choice 🙁 @#%@*$# solder pads.

I can once again recommend my filter cap, veeeery happy with it. Precision from hell.

Chris, can you remind me what this filter cap your happy with is?

Mike

Hi Dears,

I am following all this messages, but I can't see too much about sound quality. We should have some conclusion after almost one year fo trials and experiences.

I would be very nice if we state the setup of our UCDs and all the other equipment used and make statement like: "the highs where not harsh, detailed and liquid, the bass... etc".

My experience is with two UCD180, a R-core trafo (suggested in another post in the past), I used 27-0-27V 600Va, with bridge rectifiers and 10,000uF Rifa-Evox caps on each side (expensive but worth of their price). The psu gives me something like 37Vdc (well below inside the suggested range 30-45 Vdc). I believe that lower voltage is always better, at least it does not stress components too much, and this is expecially wellcomen when caps are not rated for high voltages.

I do not use any decoupling caps or other strange things. In my opinion if you did not design the entire circuit than you should use the most simple PSU. Other wise you risk to "over-filter" some bit of the spectra. Anyway, I belive in "simplicity"

...
The problem is that in general toroidals are not as dynamic as other topologies (C-core, E, R, etc). I experienced this in many cases. This affects basses, because when the music concentartes on a dynamic bass line, this requires high currents in extremely small time intervals so that trafo and caps are required to work fast, very fast. I am not an epxert but I think toroidals are not able to do that, I don't know why.


I found also very important to have extreme cure of shielding. I used a separate box for the tarfo becuase in the beginning I had probles at high frequancies. I had some noise which now has gone. Both boxes are shiled and earthed.

Bye and let me know your experiences,
Steve

Hi Steve,

I'm not hugely impressed with my stock UcD bass as of yet, but then again, I've got an ancient bridge and supply caps. I plan to upgrade soon to a 4 pole, but I'll check out what you mention too.

I also have a toriod, so your comments interest me. the thing that makes me wonder if its true though, is the chassis and power supply use to have an amp that had nothing but good bass. So there goes the toriod theory I think?
Also, I've measured the supply with a DVOM, no scope at home, and running the amp wide open from a passive preamp, (so 56V peak with the right CD) I see less than 1V peak AC deviation and the rail DC never budges even 250mV from ~60V, depending on the day. (I have UcD400's by the way.)
I have 2 15inch JBL 2234's (effecient, high output...) and the bass is very musical, but not as good as I've heard. I plan to do a few things end of month, when the wife and kids are away.
Supply caps, bridge, on board bypass... filter caps if I find some, and maybe even try a different inductor, as I have an appropriate one. Stay tuned.

Best Regards,

Mike

 

[classd4sure]

Hi Steve,

Welcome to the forum.

Conclusions are hard to come by. The intent of this thread was to see how good an already decent thing can become. We're not finished with it yet, we've really just begun.

Perhaps your proposal would be best served as another thread, since you failed to mention having modified your modules.

I think I disagree about lower voltages always being better, it's hard to make blanket statements like that in this game. I find that a marketing myth brought on by those who would boost profit margin by using lower voltage/cheaper parts. The modules are well designed and can handle their ratings, you can trust the data sheet to be right.

Certain things work best and sound best at higher voltages. My rails are 44 while loaded and 47 unloaded, well within spec and I've had no ill happenings or sound from that.

Toroids are known for having an extremely high bandwidth.. R and C cores perhaps less so. I'd really have to try a different type of core to know what I don't like about my toroid because right now I'm very happy with it, and maybe their higher bandwidth is best for class d anyway?

I've an extremely responsive supply with a 500VA toroid, dual 31Vac secondaries, static shield an mu-metal shield (on an already low emission xformer), dual IXYS 68A 600V FRED rectifiers feeding the juice directly to Jensen 4 pole 63V 15 000uF caps, 2 in // per rail. No other snubbing or decoupling whatsoever, non needed by ear, and part selection was done with not wanting to add any in mind, since I don't have a scope to measure with, it would be silly to just slap anything on and convince myself it was for the best.

I wired them in bi-phase for bass re-enforcement instead of supply pumping, and have them DC coupled to an EMU 1820M audiodock, driven fully differential.

The supply floats from the chassis with the signal ground earthed to the source at the amplifier chassis, with power ground floating from it.

Using cheap mic cable for interconnects, and 10AWG monster cable for speaker wire.

Speakers are Cerwin Vega VS-150, 400W 15"woofer 102dB efficiency @1W 1m.

The modules are modified UCD180's with AD8620BRZ, SST511 CRD's, 820uF 63V Panasonic decoupling caps, and a high stability fimm/foil polypropylene 50V 1% tol. filter cap, recommended for dolby and VCO circuits by Panasonic, lead pitch 12.5mm. (2.5mm over the recommended max).

(Mike I'd look up the part# for you again, but they're only 50V, not the best for the 400, it's at digikey though, and it's posted here not too far back as well.)

I've tried alot of different variations with these modules and everything makes a difference, like I know if you didn't modify your modules the highs are silky but not the smoothest smoothest, and less than precise.

Anyway, people claim Evox caps sound a little funny in the highs. You also didn't say what kind of bridge rectifiers you're using, they could easily benefit from snubbing if you're using the wrong kind, you really only get away with no further snubbing on them if you have soft recovery, and even then it may still benefit if you use it right.

Conclusion if you truly need one would be it's well worth modifying the modules, you're just not hearing them right if you don't, and it takes so very little it'd be a shame not to considering the gains to be had.

What my amp sounds like now is holographic, very fast and dynamic, yet relaxed, with a deep black soundstage that wraps right around you and sucks you in.

The highs could really not be more precise, something the mods helped out a great deal (filter cap upgrade), and the CRD's led to a much cleaner microdetail, really brings together the finer harmonics, especially in the midrange and above a very fine improvement.

Bass has improved alot with the addition of the FC's (power), but they added some coloration to the mids/highs, tinny, and took away alot of the air/extension in microdetail, which isn't all bad because without the bass to go with it, it was just too much and led to an unrelaxed, almost anxious feeling, I loved to hear it but not for very long.

Without the addition of the filter cap upgrade, the FC's would be unlistenable, because from midrang on up response is just dropped flat. The filter cap makes up for it somewhat.

Anyway, try to replace blanket statements with research and experimentation at all cost, your amp and your ears will thank you.

 

[classd4sure]

Re: Re: comparisions

Chris, I understand you concerns over ground loops, but my speaker connections and the inputs are not connected to chassis.
There is only one wire to chassis, and nothing else makes contact.
Well almost nothing. I wanted to try it so I cut the wimpy little wire. The amp went dead. I forgot the other wimpy wire I connected to it that pulls down shut down. Oh well. I do hear you on the potential for things like magnetic induced stuff, so the day I bring my soldering iron home, I'll try it.

The real reason, I think, for doing it is for instance if you earth your supply to the chassis, like it seems you have done, then you've connected your speaker power ground to it, right along with the signal ground (they're all common on the module), and your signal ground is no longer referenced to the source but is riding on all the noise of the power and output ground instead, even if you let it float yourself.

So the best way to ensure that the output is truly referenced to the input is to only have one connected to earth (signal ground), and the only way to make it a clean earth, is to float the power ground(and output). It's worth compromising where you have to make this happen.

You should find much cleaner/sharper resolution in the highs and microdetail, this is exactly where a holographic soundstage begins to appear, if not slap you right across the face. It's definitely one of those "wow" moments. So I look forward to your results when you do try it, because I know it did alot for me.

Chris, The loop area may increase a bit, but I'm not worried about that so much. When a cap and resistor are in series, all the volts end up on the cap, not the resistor. There will be a small AC component on the resistor, but nothing much.
It will be interesting anyways. I"m going to study the board carefully when I get my new ones. Depending on layout, there might be other good options.

Chris, can you remind me what this filter cap your happy with is?

Mike

You're right about the voltage appearing across the cap...... duh.

You should get a version of the stacked film type cap others have with their modules for best results, yours should be more immune to this.

I find the cap I used is very "tight".

It's in the ECQ-P(Z) series, 470nF 50V. You might look at the BCC 416-420 series, can get them at 63V 2%, but I think you can't expect as big as improvement as I noticed, as your stock cap is already better, probably in the ECQ polyester series.

 

[maxlorenz]

Dear all:

Chris, I understand you concerns over ground loops, but my speaker connections and the inputs are not connected to chassis.

The real reason, I think, for doing it is for instance if you earth your supply to the chassis, like it seems you have done, then you've connected your speaker power ground to it, right along with the signal ground (they're all common on the module), and your signal ground is no longer referenced to the source but is riding on all the noise of the power and output ground instead, even if you let it float yourself.

I see your concern about proper PSU wiring. I may be one of the victims of non-perfect wiring 🙁
Now my UCD400 are wired like this: center taped toroid referenced to common cap's copper plate and this connected to BOTH, module's "PS ground" pin AND chassis' "star ground point"; safe earthing point is connected to another chassis point next to the power entry. Module's "on pin" is connected also to "star ground" chassis point.
(signal input pin 1 is attached only to chassis for now (Rane))

Questions:
Do I have to disconnect wire going from common cap's copper plate to "star ground"?
Thus maintaining caps to module's PS ground pin connection.

Aren't the "T pieces" connected to ground anyway, making all grounds connected?

How can you float the output?

Thanks a lot
Mauricio

 

[Portlandmike]

Dear all:




I see your concern about proper PSU wiring. I may be one of the victims of non-perfect wiring 🙁
Now my UCD400 are wired like this: center taped toroid referenced to common cap's copper plate and this connected to BOTH, module's "PS ground" pin AND chassis' "star ground point"; safe earthing point is connected to another chassis point next to the power entry. Module's "on pin" is connected also to "star ground" chassis point.
(signal input pin 1 is attached only to chassis for now (Rane))

Questions:
Do I have to disconnect wire going from common cap's copper plate to "star ground"?
Thus maintaining caps to module's PS ground pin connection.

Aren't the "T pieces" connected to ground anyway, making all grounds connected?

How can you float the output?

Thanks a lot
Mauricio

Mauricio,

Chris obviously has a slightly differnt take then me on this but we agree on most all.
If you have more than one wire to chassis ground, it might be trouble.

FOR SURE connect input signal ground to input (RCA, or XLR).
That connector FOR SURE should not be chassis grounded.

The inputs + and - should be connected to the input(RCA, or XLR)
if its a single ended RCA, then you should have two wires, one input and signal ground) connected to the sleeve of the RCA.

From what I interpet of your discription, just get input 1 off of the chassis, and put it to the input and all will be much much better.
Also, if the other chassis ground connection you mention is a three prong ground..... loose it.

I found that I experienced the staging improvements that Chris mentioned by doing that alone, Thanks to Chris . I will try floating the whole supply, and will report the results (soldering iron is home again🙂 , but as an EE, I have a hard time seeing the benifit as nothing is connected to the chassis anywhere else, and for sure see some downsides in loss of shielding by not connecting it to ground. I expect no difference, but its worth a try just to see and put it to rest. I've been fooled before with what shouldn' t matter.

Regards,

Mike

 

[classd4sure]

Dear all:

I see your concern about proper PSU wiring. I may be one of the victims of non-perfect wiring 🙁
Now my UCD400 are wired like this: center taped toroid referenced to common cap's copper plate and this connected to BOTH, module's "PS ground" pin AND chassis' "star ground point"; safe earthing point is connected to another chassis point next to the power entry. Module's "on pin" is connected also to "star ground" chassis point.
(signal input pin 1 is attached only to chassis for now (Rane))

Questions:
Do I have to disconnect wire going from common cap's copper plate to "star ground"?
Thus maintaining caps to module's PS ground pin connection.

Aren't the "T pieces" connected to ground anyway, making all grounds connected?

How can you float the output?

Thanks a lot
Mauricio

Can't say with 100% certainty, I've never tried the copper plate thing. I know in this area wiring is critical.

I've also never tried floating the supply ground with a center tap, but I imagine you could and it shouldn't hurt to try. Leave the CT connected to the plate common point, keep both module power grounds connected at the very same spot on that plate, disconnected the plate from the chassis so it that it floats from it. I thought you floated your pin 1 signal ground, not connected it to chassis?

After you float the supply power ground from chassis, you want to ensure your input signal ground is referenced to the source, that will mean grounding it to chassis at point of entry. You're free to experiment in this area. I kept my chassis earthed and lifted the earth of the source, I also had good luck with earthing the chassis, and breaking the input signal ground loop at one end of the shield.

Just make sure the signal ground = source ground (connected to chassis) and supply power ground = floating from it, that more less "floats" the speaker ground off the signal ground.

Hi Mike, I hadn't really recommended you disconnect earth from chassis, but rather the supply ground from the chassis, that's assuming you'd keep the signal ground connected to it at the point of cable entry though, which it sounds like you haven't done, so your results from floating the supply further aren'tn likely to be noticeable I think. If you wanted to ground your signal inputs to the chassis though you may want to reconsider floating the supply, still looking forward to your results.

Regards,
chris