My UcD adventure

[justcallmefrank]

Hi all,

First of all, i'd just like to point out that i've not being doing this all that long, probably moreso in the past year or so. Most of my time gets spent on my car among other things. Basically what i'm trying to say is i'm an interested amateur

I previously built a Gainclone and while it was a good introduction I was never satisfied with the way it sounded in comparison with some of the Bel Canto or NEW amps I played around with.

So what did I do? I built a UcD180-based twin-monoblock stereo amplifier. Its spec sheet lists like this per channel:
Harbuchs 30V 160VA transformer
IXYS rectifier diodes
2 x 10000uF 50V Nichicon Super Through caps
UcD180AD module
Vampire RCA
Cardas CPBP binding post
Kimber wiring
Cardas wiring for signal wiring

It was built into an old Philips tuner case to match my Gainclone which was in the amplifier case of the same set. It has a pair of high intensity LED's which light up the front panel to look just like an old tuner.
Pics are as follows:


I've tried it out on various recordings at home, and finally took it into WAR Audio yesterday where i'm personal friends with the owners, to try it out against some other amps on some different sorts of speakers.

The setup we were listening to it on consisted of a Bel Canto PLayer, feeding a Bel Canto Pre6 pre-amp then onto the amplifiers. The speakers were custom boxes consisting of a pair 5" Focal drivers and a Raven ribbon tweeter each. The interconnects/cabling were all of high quality, this I know, but i'm not going to go into detail for the fact I really don't know :P

We listened to multiple tracks including Lior, Dallas Crane and a couple of others, until we came to the one that means the most to my listening tastes. This probably isn't going to gel with everyone, but the track in question was "The Crystal Method - Busy Child". It combines a lot of subtle sounds, some big bass hits and some detailed highs that when with the right equipment really punch you in the guts then make your hair stand on end.

The amplifier was above and beyond the level of my Gainclone as I'd expected, but the real test was this reference song, as not only did I know it back to front, so did one of the owners. We listened to the entire track, all 7 minutes and 25 seconds and sat for a second to reflect. It was clear there was power, but it lacked detail and overall was a bit "woolly". Apologies for my descriptions, I find it hard to quantify these sorts of things into words. In isolation though, it was pretty good.

For comparisons sake the amplifier we chose to compare it to was the NuForce 9 SE. (I don't want a b***h-fight here, I'm just offering my opinion and i've got some questions to ask later on.) Everything else was the same. The same track was played, and we tried to set the volume to about the same. We then started the track from the beginning again. Right away, the difference was clear and obvious. This is going to cause s**t, but hear me out. I'd hoped the UcD was comparable, I'd fully expected the NuForce to be superior, but neither of us had expected it to be so much superior.

Straight away there was a level of detail we never experienced with the UcD, everything was so much tighter and crisp and the highs were probably the best we'd ever heard that song. In hindsight, the UcD probably didn't match the experience i've had listening to that song either using a Bel Canto eVo2 or NEW amps the previous time I came.

Needless to say, I was disappointed, but not one to give up, I'm keen to get stuck into my UcD to try to take the challenge to the NuForce. If someone could point me in the direction of any comparisons between the two i'd be most grateful, the unfortunate thing I find is that every search I do leads to a b***h fight...

First off, based on the pictures at the top of the post an the components list i've provided, can anyone identify any deficiencies in my system (excluding the 100% standard modules) that I may have introduced? I'm only an amateur, the decisions I made were based on lots of reading, speaking to people and asking questions, but it's quite possible for me to make errors.

Secondly, I'd had a look at the UcD hot-rodding thread, but it's just massive, and I've spent a couple of hours this morning reading all sorts of other stuff! Someone suggested a FAQ in there, but i've not come across it if it exists. Can anyone point me in the direction of a concise list of mods that would be beneficial.

I believe in the UcD technology, and recognise that a lot of the inadequacies I experienced are due to implementation and lack of modifications, and I'd like to remedy that.

I'd appreciate any feedback, good or bad, but please, can we keep this clean?

Cheers,
Nathan

[ashok]

Is your UcD 180 a ST or AD variety ? ST meaning standard input ( NE series) or AD - with AD8620 ?
I'm inclined to believe that you might hear a difference here.

Power supplies of course matter a lot. I can't say what you should really do but get some ideas from the Gain Clone and UcD threads. If it ain't right , try some variations , no matter what parts you use.
Do you have any R-C snubbers on the supply lines ? I'm not sure if that can really be called a 'snubber'.

How about internal ground lines and cabling ?
Have you tried Cat5 interconnects ? Yeah it shouldn't make a difference (!) BUT have you tried it ?

Nothing in audio can be taken for granted till you have tried it in your own system.

My ClassD has very clean tight bass and extremely clean HF.
nothing woolly about it .
Cheers.

[Baldin]

Hi Nathan

Think you're opening a real can of worms here

Would have been interesting if your listening test had included some more "neutral ground" (neutral in terms of war ) using a Krell or ML as reference for the rest (don't think anyone would object to saying these where good sounding amps).
So maybe you could try this out next time you visit the shop.

As for your constrution, it seems you are using the chassis for grounding at least 4 different places!!!

The chassis should not be used for a star ground. You use expensive wires, but everything might actually end up going through the steel chassis, inducing switching noise into the circuit and audio path.

Try using the following drawing which is taken from Douglas Self's very good book "Audio Power Amplifier Design Handbook". Though it is mostly about class-ab it is still worth reading, and can still teach some basics about audio.

The red wire you have going from one side to the other, what is this for?

Try keeping the wires sa short as possible.

I don't think that doing modifications should be necessary to get good sound, I'm sure Bruno has done an exelent job in the first.

Also the difference between the two different models using two different buffers, shouldn't do much difference.

As I understand you where saying that there where a huge difference between the two amps.

If you could post a drawing of exactly how you have wired your construction it could help see if there is something to change.

[justcallmefrank]

Originally posted by Baldin
Hi Nathan

Think you're opening a real can of worms here

Hehe, I knew that was a possibility, hence I was so cautious about how I worded things. I've seen the shitfights :P

Originally posted by Baldin
Would have been interesting if your listening test had included some more "neutral ground" (neutral in terms of war ) using a Krell or ML as reference for the rest (don't think anyone would object to saying these where good sounding amps).
So maybe you could try this out next time you visit the shop.

I tried what was available without putting them out too much, I actually disrupted his testing of some new speakers he was designing. Then there is the possibility that they don't have one of those lying around Knowing him though, I wouldn't be surprised.

Originally posted by Baldin
As for your constrution, it seems you are using the chassis for grounding at least 4 different places!!!

The chassis should not be used for a star ground. You use expensive wires, but everything might actually end up going through the steel chassis, inducing switching noise into the circuit and audio path.

Okay, point noted. Currently there are 3 places where the ground is connected to the chassis. These are the main one at the back which has the ground from the caps and the one directly off the IEC plug. The other two are off either rectifier bridge. So are you saying it would be better to have them all coming into one single ground? It's definetly something I can do pretty easily.

Originally posted by Baldin
Try using the following drawing which is taken from Douglas Self's very good book "Audio Power Amplifier Design Handbook". Though it is mostly about class-ab it is still worth reading, and can still teach some basics about audio.

Thanks for that.

Originally posted by Baldin
The red wire you have going from one side to the other, what is this for?

Try keeping the wires sa short as possible.

The red wire is the wire running to the LED's. There is one running off each bridge. The green ones are the trigger wires for the UcD's. I tried to keep everything as short within the limitations of the case and around the massive real estate taken up by the transformers and those caps.
Funnily enough, i'm actually going to be moving the bridges to above the caps themselves so I have room for if I want to swap in another module for testing (i.e. NuForce).

Originally posted by Baldin
I don't think that doing modifications should be necessary to get good sound, I'm sure Bruno has done an exelent job in the first.

Also the difference between the two different models using two different buffers, shouldn't do much difference.

This is true, it was more trying to pin down the suggestions that Bruno did give that improved sonic quality. It's so hard to find them when that thread is so massive!

Originally posted by Baldin
As I understand you where saying that there where a huge difference between the two amps.

If you could post a drawing of exactly how you have wired your construction it could help see if there is something to change.

The difference was night and day, which surprised me. This suggested to me that I'd done something wrong, because I really expected to be blown away. The other part of me was a little underwhelmed because I wanted my David to some close to Goliath Both of them didn't really have anything nice to say about it other than it had grunt.

[Baldin]

You should form 2 star points, one for each channel.

The starpoints should not be directly between the reservoir capacitors, but should be located only a few centimeters from their midpoint. Center tab on the trafo should go to the midpoint between the caps.

Chassis should go to the power inlet ground.

Input terminals ground should go to the chassis at the entry point.

[lucpes]

There are two coupling capacitors near the UcD modulator (the perpendicular small board). Ditch them if you have the AD version, or change the standard 5532 for something with low offset (say OPA2134) and ditch them.

As for grounding, I had the best sonic results when I let the grounds unconnected to the chassis (power inlet only connected there), and also floated the input grounds using a 10R resistor.

[SSassen]

I'm sorry, but with that kind of build quality you'll never tap the true potential of the modules. Even NuForce does a better job with their amplifiers and they forego just about every rule in the book. You however seem to have just thrown assorted bits and pieces into an old chassis at rnadom and wired them up. By doing so you more than disqualified yourself from making any observations, or pass judgement on the merits of these modules.

Best regards,

Sander Sassen
http://www.hardwareanalysis.com

[justcallmefrank]

Originally posted by SSassen
I'm sorry, but with that kind of build quality you'll never tap the true potential of the modules. Even NuForce does a better job with their amplifiers and they forego just about every rule in the book. You however seem to have just thrown assorted bits and pieces into an old chassis at rnadom and wired them up. By doing so you more than disqualified yourself from making any observations, or pass judgement on the merits of these modules.

Best regards,

Sander Sassen
http://www.hardwareanalysis.com

I'm sorry, but I'm just going to have a big WTF here. I came here looking for assistance. I KNOW something is wrong, that's the whole point, and you just waltz on in here being a prick without offering any form of advice. I've actually looked at your website and on the strength of your results I knew I was nowhere near the potential of these modules.

I didn't suggest the NuForce amplifier was better than the UcD, I said it was better than mine, because it was!? I came on here to try and improve it.

Judging by your response, I've done some fundamentally wrong things. Please, point me in the right direction to correct them. I don't come from an audio background, I don't come from an electronics background, I just wanted to give something a go and I like to learn about this sort of stuff. That is why I made it clear at the beginning, I AM AN AMATEUR.

I didn't throw assorted bits and pieces, I spoke to numerous people and selected components that were recommended. The chassis was just used for its retro look. The fact that I may have done something wrong isn't through ignorance, it's through a lack of understanding, which I'm here to remedy.

Please, I'm not looking for an argument, I really am not, I just want to achieve the potential of these units and want to know what I can fix with my setup to do it...

Cheers,
Nathan

[justcallmefrank]

Originally posted by lucpes
There are two coupling capacitors near the UcD modulator (the perpendicular small board). Ditch them if you have the AD version, or change the standard 5532 for something with low offset (say OPA2134) and ditch them.

As for grounding, I had the best sonic results when I let the grounds unconnected to the chassis (power inlet only connected there), and also floated the input grounds using a 10R resistor.

Thanks for that, I'll pull the modules out because I've got the AD version.
Thanks for the input on the ground too

[justcallmefrank]

Originally posted by Baldin
You should form 2 star points, one for each channel.

The starpoints should not be directly between the reservoir capacitors, but should be located only a few centimeters from their midpoint. Center tab on the trafo should go to the midpoint between the caps.

Chassis should go to the power inlet ground.

Input terminals ground should go to the chassis at the entry point.

I get your first point, but i'm a little confused about the second. Are you saying have a starpoints between the centre of the case and the modules?

I'm not quite sure what you mean about the center tab on the trafo either?

I get the chassis ground.

When you say input terminals, are you talking about the RCA's? Sorry, trying to adjust to the terminology. If so, I thought according to the sheet that came with the modules that it is connected to the pin on the modules themselves?