[Kevin P]

There are no reviews yet.   We have only been building them for a few months so we just don't have the installed user base yet.

I'm sending out a seven channel to one of the Home Theater magazines in a few weeks.   It takes them months to get to publication though and we will probably have people online making comparisons far before that point.

There are a lot of user reviews of the Hypex modules we use.

[guest1632]

There are no reviews yet.   We have only been building them for a few months so we just don't have the installed user base yet.

I'm sending out a seven channel to one of the Home Theater magazines in a few weeks.   It takes them months to get to publication though and we will probably have people online making comparisons far before that point.

There are a lot of user reviews of the Hypex modules we use.

Can you steer me to some of those reviews? Thanks.

Ray

[trekker]

I think Kevin may be refering to this site: http://www.diyaudio.com/forums/forumdisplay/f-49.html  All types of talk about digital amps.

[Kevin P]

There are no reviews yet.   We have only been building them for a few months so we just don't have the installed user base yet.

I'm sending out a seven channel to one of the Home Theater magazines in a few weeks.   It takes them months to get to publication though and we will probably have people online making comparisons far before that point.

There are a lot of user reviews of the Hypex modules we use.

Can you steer me to some of those reviews? Thanks.

Ray

trekker nailed probably the number one source.

[guest1632]

There are no reviews yet.   We have only been building them for a few months so we just don't have the installed user base yet.

I'm sending out a seven channel to one of the Home Theater magazines in a few weeks.   It takes them months to get to publication though and we will probably have people online making comparisons far before that point.

There are a lot of user reviews of the Hypex modules we use.

Can you steer me to some of those reviews? Thanks.

Ray

trekker nailed probably the number one source.

Hi Kevin,

Wow! Looks like I could spend all night reading this stuff. One thing I came across was the possible removing the input cap. Apparently things just opened up. But then, you have to deal with the DC offset proboem. Just was wondering if you had looked in to that slight mod? Also saw your thread there too. You're a good guy Kevin, keep it up.

Ray

[Rocket]

Hi Kevin,

Do you perform any mods to the ucd module or are they stock?

Regards

Rod

[Kevin P]

Hi Kevin,

Wow! Looks like I could spend all night reading this stuff. One thing I came across was the possible removing the input cap. Apparently things just opened up. But then, you have to deal with the DC offset proboem. Just was wondering if you had looked in to that slight mod? Also saw your thread there too. You're a good guy Kevin, keep it up.

Ray

Yes... there is a lot of information out there.   You have to take a lot of what is said with a grain of salt.    

We can modify the modules but it removes any trace of warrantee on the module.   I consider DC blocking a necessity.   There are a few other caps that people upgrade but I've stuck with what Bruno uses.   A lot of the modifications increase RFI emissions and have other tradeoffs.    There really isn't much that can be done to improve their performance without some sort of engineering tradeoff.  

The exception would be the power supply.   We could probably use a slit foil cap or Blackgate and get a DIFFERENT sound.   Better or worse is going to depend on system dynamics and the individual.  

I'm not sure what thread you are refering to... must have been a good one though.  

[Kevin P]

Hi Kevin,

Do you perform any mods to the ucd module or are they stock?

Regards

Rod

Our standard amps are stock.   As I said, there isn't a lot that can be done without an engineering tradeoff.   I know people LOVE to own a "tweaked" amp but you also have to know when to leave something alone.   Bruno made good design choices and changing a few caps in order to make it sound as though we are "improving" the design would just be a marketing ploy.

The old saying "if it's not broken, don't fix it" applies.

[guest1632]

Yes... there is a lot of information out there.   You have to take a lot of what is said with a grain of salt.   ;-)  

We can modify the modules but it removes any trace of warrantee on the module.   I consider DC blocking a necessity.   There are a few other caps that people upgrade but I've stuck with what Bruno uses.   A lot of the modifications increase RFI emissions and have other tradeoffs.    There really isn't much that can be done to improve their performance without some sort of engineering tr ...

Hi Kevin, I think it was in the hotrodding the UCD400. There was some discussion about removing the imput cap, or replacing it with a higher quality cap. There is this discussion about comparing the LC audio versus the ucd modules. That is when this whole thing came up I think Bruno then came up with some ideas to get around the DC offset issue. Anyway, it might be worth discussing this with him. Apparently, the improvement wasn't subtle. I don't know if this same cap is on the 180W module. If indeed, at time of purchase, I am more than happy to get that cap replaced with a higher quality one. He too did aknowledge that the module could be improved. I don't want to do anything that would cause a problem later. If we have any engineers amongst us, maybe someone could see about how to, or what value to use with a trimming resistor to bring the offset down to a negligible value.

Ray

Ray

[guest1632]

Here is the big daddy with 7 channels of UCD400 in a single 2U chassis.   Dimensions 12.5" deep, 16.75" wide and 3.5" tall.  

With 1.6KVA of transformer and 82,000uF of capacitance the power supply has plenty of reserves.   We have dialed in the grounding scheme with a little help from Dan Wiggins.  

As a recommended option we have the Exodus DC & RFI filter.  This is the same filter network as we use on our Exodus JR Filters.   Heat sinking is provided via a 3/16" sheet of aluminum which mounts to  ...

Hi Kevin, What does the ad8620 do? Is this a replacement chip? any advantages with this ad8620 chip?

Ray

[trekker]

If I'm correct, the AD862 is an Analog Devices op-amp description here: http://www.analog.com/en/prod/0%2C2877%2CAD8620%2C00.html

"AD8620 (dual) are very high precision JFET input amplifiers featuring ultralow offset voltage and drift, very low input voltage and current noise, very low input bias current, and wide bandwidth.
...

Applications for the AD8610 and AD8620 include electronic instruments;  ...  and high quality audio."


Seems like an upgrade to me.

Arnold

[Kevin P]

Hi Kevin, I think it was in the hotrodding the UCD400. There was some discussion about removing the imput cap, or replacing it with a higher quality cap. There is this discussion about comparing the LC audio versus the ucd modules. That is when this whole thing came up I think Bruno then came up with some ideas to get around the DC offset issue. Anyway, it might be worth discussing this with him. Apparently, the improvement wasn't subtle. I don't know if this same cap is on the 180W module. If indeed, at ti ...

We can certianly trim DC offset via the resistor.   You have to understand what Bruno says though in the context of a DIY forum is different than what may be cost effective or practical.   Many of the DIYers are willing to take risk with their amplifier modules by doing modifications.   Anytime you modify or work on something there is chance of causing harm and that adds to the cost of a build.

If you wanted modifications done we can do them.   All of them will drive up the price though.

[Kevin P]

If I'm correct, the AD862 is an Analog Devices op-amp description here: http://www.analog.com/en/prod/0%2C2877%2CAD8620%2C00.html

"AD8620 (dual) are very high precision JFET input amplifiers featuring ultralow offset voltage and drift, very low input voltage and current noise, very low input bias current, and wide bandwidth.
...

Applications for the AD8610 and AD8620 include electronic instruments;  ...  and high quality audio."


Seems like an upgrade to me.

Arnold

There is nothing wrong with the stock ones either.

[trekker]

I was wondering what type of warranty does the amps have stock?  Does it change if we have the mods done by DIY?

Thanks,

Arnold

[guest1632]

If I'm correct, the AD862 is an Analog Devices op-amp description here: http://www.analog.com/en/prod/0%2C2877%2CAD8620%2C00.html

"AD8620 (dual) are very high precision JFET input amplifiers featuring ultralow offset voltage and drift, very low input voltage and current noise, very low input bias current, and wide bandwidth.
...

Applications for the AD8610 and AD8620 include electronic instruments;  ...  and high quality audio."


Seems like an upgrade to me.

Arnold

There is nothing wrong with the stock ones either.

Hi Kevin, Ok, so if nothing is wrong with the stock IC's, then what is the advantage of the ad8620? Several posters had tried the removal/short of the imput cap, with not so subtle differences. It might well be worth the investigation. I do understand the reason for the protection against the DC offset. Once the correct value of the resistor is found, to null out the DC offset, then it could be replaced relatively easily. . I think?

Ray

[Kevin P]

I was wondering what type of warranty does the amps have stock?  Does it change if we have the mods done by DIY?

Thanks,

Arnold

We cover parts & labor for anything for a year.   After that we charge parts cost for repairs and minimal labor.     There isn't much to go wrong as long as the modules are kept stock.   Once you start modifying modules (removing DC blocking) the opportunity for problems expands quickly.  

For modified UCD modules it's going to be a case by case basis for warrantee work.   If all we did was replace a capacitor with another brand it's not an issue.   If we modify to remove functionality or protection circuits then that is another issue.  

I'll probably work up some of the more common modifications and have a standard "modified UCD" package but that will take some time.

[Kevin P]

Hi Kevin, Ok, so if nothing is wrong with the stock IC's, then what is the advantage of the ad8620?

The advantage is that we make more money on the AD8260.  

Seriously.... it's a better opamp from a technical standpoint.    Some would claim it sounds better but it's going to depend on several variables.   I'm always sceptical unless I have a lot of A/B experience with a modification and many times a modification isn't universally liked.  It seems foolish to me to make recommendations based upon something that I'm not sure is actually better or not.

 Several posters had tried the removal/short of the imput cap, with not so subtle differences. It might well be worth the investigation. I do understand the reason for the protection against the DC offset. Once the correct value of the resistor is found, to null out the DC offset, then it could be replaced relatively easily. . I think?

Ray

I don't know until I've tried it.   I'm very sceptical of things that are said online especially when I don't know the individuals posting.   Proud papa syndrome is very real.

[guest1632]

We can certianly trim DC offset via the resistor.   You have to understand what Bruno says though in the context of a DIY forum is different than what may be cost effective or practical.   Many of the DIYers are willing to take risk with their amplifier modules by doing modifications.   Anytime you modify or work on something there is chance of causing harm and that adds to the cost of a build.

If you wanted modifications done we can do them.   All of them will drive up the price though.

Hi Kevin, ok, so I am not asking for a definite price, but an approximate one. I guess you haven't had an opportunity to listen to the amp with the ad8620 in it? So we leave it stock remove the cap and trim down the offset to say under .2 mv. I wonder if this process would be cheaper than replacing the cap with a better quality one.

Ray

[Kevin P]

Hi Kevin, ok, so I am not asking for a definite price, but an approximate one. I guess you haven't had an opportunity to listen to the amp with the ad8620 in it? So we leave it stock remove the cap and trim down the offset to say under .2 mv. I wonder if this process would be cheaper than replacing the cap with a better quality one.

Ray

In terms of modifications I'm not comfortable selling something until I've had a chance to at least make the modifications myself and better evaluate what can and cannot be done.   It's not a matter of price, it's a matter of making sure I'm putting something out the door that won't cause you and I problems down the road.

I've have not built an amp with the AD8620 yet so I've not done A/B comparisons between it and the stock amp.

[guest1632]

In terms of modifications I'm not comfortable selling something until I've had a chance to at least make the modifications myself and better evaluate what can and cannot be done.   It's not a matter of price, it's a matter of making sure I'm putting something out the door that won't cause you and I problems down the road.

I've have not built an amp with the AD8620 yet so I've not done A/B comparisons between it and the stock amp.

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 not a Nuforce, or CI, come pretty damn close. There were people who were really in to tubes, and the sound they produce. After building these amps, they wouldn't go back. That kinda says a lot. Yeah, I do take a lot with a grain of salt, but I figure if a lot of posters came up with the same conclusions, then maybe, proud Papa isn't the only factor here.  

As far as what you put out the door for sale, I certainly understand your thinking. That's why I am discussing this with you now. I certainly don't want to do the mods later. Unless I find out anything different, I'll let it rest for now. I hope you'll pull the cap and see what you get Frankly, if it were subtle, I wouldn't worry about it. The description was pulling a blanket off the sound of the amp. Later.

Ray