[Kevin P]

Hi Kevin, So then how much mula should I send you so you will then try the two mods: 1: removal of the cap and trim the resistor to remove the offset, and 2: try the AD8620. If I could see, then I guess I'd be one of those DIYers looking for a way to make the amp better. Instead, I'm stuck relying on other people to do the job for me.

I'll look around in the form a little more and see if any conclusions about the value of the resistor are mentioned anywhere. It does seem that these amps while perhaps no ...

Until I get time to evaluate changes to the modules myself and which ones I'd consider implementing on a commercial scale we are only going to sell the standard modules.    I'm just unwilling to commit to changing something based upon a thread in a forum.

So for now... our policy is standard modules only.    When I get free from a couple other projects I'll consider looking into modifications on the UCD modules.

[guest1632]

Until I get time to evaluate changes to the modules myself and which ones I'd consider implementing on a commercial scale we are only going to sell the standard modules.    I'm just unwilling to commit to changing something based upon a thread in a forum.

So for now... our policy is standard modules only.    When I get free from a couple other projects I'll consider looking into modifications on the UCD modules.

Hi Kevin, Well, the only definite I found with Bruno's blessing was installing the AD8620 without the two imput caps, posed no DC offset issues. It is low enough, where the only then concern should be the upstream components. The concensus did seem to be if those two imput electrolytics were to be replaced, then use either Pantasonic caps or Ori caps.  Those caps do you use in the supply? Orie or Panasonic caps appeared to be the way to go.  People were reporting the Panasonic caps, especially because they are cheap, and did the job nicely. There is a .68 electrolytic cap on the LC output, that Audience via Orie is building especially for the UCD modules. So there you have it. Those three mods, the Panasonic  capse in the supply, removal of  the two imput caps (if you are using the AD8620), and the replacement of the .068 cap in the output section with an Orie cap of that value with a 450V rating. Those seem to be the biggets mods that would make the biggetst difference. There was some discussion about replacing the "bootstrap" cap. As for me, I think I'd leave that one alone. It too had been replaced with a Panasonic cap with subtle results at best. So now, I've done your investigation for you. I'd probably only do the removal of the imput caps, with the AD8620 installed. wouldn't take a chance with the stoc chip. You might check with Audience on that Orie cap. Thanks for your time.

Ray

Ray

[Al Garay]

Here is a  vote of confidence for Kevin's choices.

You can go crazy over-analyzing the possible options especially if you follow the diyaudio discussions.  I heard Kevin's 5 channel UcD180 amps and thought they did extremely well in comparison to my beloved AKSA Nirvana amps.

[guest1632]

Here is a  vote of confidence for Kevin's choices.

You can go crazy over-analyzing the possible options especially if you follow the diyaudio discussions.  I heard Kevin's 5 channel UcD180 amps and thought they did extremely well in comparison to my beloved AKSA Nirvana amps.

Hi Al, Well, I already did that. That's why I checked in to this for Kevin, so he wouldn't have to go crazy. The only things I have to find out are the schematic codes, so he doesn't even have to deal with that.

[Kevin P]

Here is a  vote of confidence for Kevin's choices.

You can go crazy over-analyzing the possible options especially if you follow the diyaudio discussions.  I heard Kevin's 5 channel UcD180 amps and thought they did extremely well in comparison to my beloved AKSA Nirvana amps.

Hi Al, Well, I already did that. That's why I checked in to this for Kevin, so he wouldn't have to go crazy. The only things I have to find out are the schematic codes, so he doesn't even have to deal with that.

At them moment Ray I'm only going to sell the modules stock.  

I'd recommend checking with some of the guys who specialize in modifying equipment if you are interested in modifications.    You could also check into the Channel Island amps.    Dusty does some modifications to the UCD modules for his amps.

[Gordy]

I'll second Al's vote of confidence!

Ray, just to ease your mind, I've moded both the standard HcD module and the 8620 buffered module and, all diyaudio thread hyperbole aside, the removal of the input caps, c-23 and c-24,  was the only mod that resulted in any real sonic difference.  Swapping out the oem 480uF caps for the 680uF Panasonic FC's added a smidgeon of jump perhaps.  I did the 22uF low voltage caps at the same time as the 680's so can't comment other than above.

For two channel sound the fast ticket would be to purchase one of Kevin's excellent transformer Django pre's (the ultimate DC blocker!!!) and ask him to jumper the HcD inputs  imho etc.

I'll worry about the output mod if and when the Audience caps come to market!!!

[Kevin P]

I'll second Al's vote of confidence!

Ray, just to ease your mind, I've moded both the standard HcD module and the 8620 buffered module and, all diyaudio thread hyperbole aside, the removal of the input caps, c-23 and c-24,  was the only mod that resulted in any real sonic difference.  Swapping out the oem 480uF caps for the 680uF Panasonic FC's added a smidgeon of jump perhaps.  I did the 22uF low voltage caps at the same time as the 680's so can't comment other than above.

For two channel sound the f ...

The main problem with removing DC blocking is that if the preamp is switched at a later date you can toast someone's speakers.    Since many of my customers have many tens of thousands of dollars wrapped up in their speakers I don't want to do anything that would risk serious damage to them.    It's just not worth the minimal performance gain that can only be heard in an A/B comparison.  

I have DC blocking on my own amplifiers even though I can control DC on the source.   It's just not worth doing and I'm certainly not going to send a product out the door that will damage speakers when used with many sources.

[guest1632]

At them moment Ray I'm only going to sell the modules stock.  

I'd recommend checking with some of the guys who specialize in modifying equipment if you are interested in modifications.    You could also check into the Channel Island amps.    Dusty does some modifications to the UCD modules for his amps.

Hi Kevin, The only thing I'm gonna do when I order my (haven't decided which one yet) amps, will probably order it with the AD8620, and have at that time just remove the imput caps. That's the only mods I'm gonna want to have done. Otherwise, I'm gonna leave wel enough alone. $50 is worth it to me. Then before you ship it out you can take a listen and see for yourself. I already have an inquiry in with Dusty about this. I'm a tweaker at heart, but I also know when to quit. What brand of caps do you use in the supplies? Just curious. Thanks.

[guest1632]

The main problem with removing DC blocking is that if the preamp is switched at a later date you can toast someone's speakers.    Since many of my customers have many tens of thousands of dollars wrapped up in their speakers I don't want to do anything that would risk serious damage to them.    It's just not worth the minimal performance gain that can only be heard in an A/B comparison.  

I have DC blocking on my own amplifiers even though I can control DC on the source.   It's just not worth doing and  ...

Hi Kevin, From a person who is providing a service or product, by all means you have to make sure that what you put out is not gonna have any problems later. With the default chip in there, you're absulutely right. I certainly wouldn't risk the trial. This is why I specified the use of the AD8620. It's offset is low enough to where I'm not concerned. Most components upstream have some form of output that is DC blocked. Bruno mentioned this several times, that the DC offset is low enough that the only possible worry would be what is upstream. If I have it done, then only I and I alone will have to take responsibility if something other than the amp goes wrong. I'll let it go for now til I place my order, and then we can discuss this further and come to an agreement. Thanks again for your time.

[guest1632]

I'll second Al's vote of confidence!

Ray, just to ease your mind, I've moded both the standard HcD module and the 8620 buffered module and, all diyaudio thread hyperbole aside, the removal of the input caps, c-23 and c-24,  was the only mod that resulted in any real sonic difference.  Swapping out the oem 480uF caps for the 680uF Panasonic FC's added a smidgeon of jump perhaps.  I did the 22uF low voltage caps at the same time as the 680's so can't
Hi Gordy, Well, what differences did you hear? Do you have the 180 or the 400? Are you gonna do the Panasonic caps in the power supply? What is this transformer thingee? Did you try that too?