[Regalma]

I have an amp I built from the SDS-258 kit. When I play it loud, like over 90 dB at my listening postion it cuts out momentarily during some passages. I have had my current speakers for several years. I have never experienced this with any other amp. These have ranged just over 100w/ch in receivers to 200 w/ch class D monoblocks.

I have read through posts and a couple of other folks have experienced. One put it down to running their Squeezebox at full output the other to pulling down the AC. I am experiencing this with sources other than my SB. My system runs off a dedicated 20 A line. There is nowhere near enough draw to pull it down. Just to confirm this I monitored the voltage while, including the cutouts. The voltage never dropped more than a few 1/10ths and never dropped below 120V.

I have emailed ClassD and he agrees that this should not be happening. He very generoulsly promised me a new module. But this was about three weeks ago and I have heard nothing since. Multiple follow-up emails have not been responded to. I feel like I have to deal with this myself.

Has anyone else experienced this?

By the way I love the amp, I really would hate give it up. I never thought an amp could make this big a difference.

[poseidonsvoice]

I have an amp I built from the SDS-258 kit. When I play it loud, like over 90 dB at my listening postion it cuts out momentarily during some passages. I have had my current speakers for several years. I have never experienced this with any other amp. These have ranged just over 100w/ch in receivers to 200 w/ch class D monoblocks.

I have read through posts and a couple of other folks have experienced. One put it down to running their Squeezebox at full output the other to pulling down the AC. I am experiencing this with sources other than my SB. My system runs off a dedicated 20 A line. There is nowhere near enough draw to pull it down. Just to confirm this I monitored the voltage while, including the cutouts. The voltage never dropped more than a few 1/10ths and never dropped below 120V.

I have emailed ClassD and he agrees that this should not be happening. He very generoulsly promised me a new module. But this was about three weeks ago and I have heard nothing since. Multiple follow-up emails have not been responded to. I feel like I have to deal with this myself.

Has anyone else experienced this?

By the way I love the amp, I really would hate give it up. I never thought an amp could make this big a difference.

Tom is sometimes hard to get hold of, but hopefully your e-mails are not going into the spam folder.

I haven't had any issues of late contacting him. I usually use the form on the website, instead of e-mailing him directly to minimize the above issue. In any case, you can forward him your mailing address so you can get a new module. I would also mail him your old module so he can find out what is going on.

I wouldn't expect you to have an oscilloscope, which is what it sounds like this is leading to.

All the best, and yes I agree, it's a nice amp design.

Anand.

[Regalma]

I do a scope. But I would really like to know if this is an issue with the design or my module.

[poseidonsvoice]

I do a scope. But I would really like to know if this is an issue with the design or my module.

I owned the amp for almost 2 years. I would play them on my speakers at ear splitting levels. Never the issue you described.

Best,
Anand.

[Letitroll98]

One, I'm not really sure what your question is and two, shouldn't it be posted in the $175 amp thread?  So could you please clarify?  The post hints at sour grapes, yet has some positive things to say as well, so I wouldn't want to prejudge the intent without your clarification.  Please include any reasons it shouldn't be merged into the $175 amp thread.

Thnx,
Letitroll98
Facilitator

[Regalma]

Move it where ever you think it most appropriate. I was trying to see others were having this problem since was mentioned a couple of times in another thread. They had found solutions but those solutions didn't work for me. I was hoping someone else had my experience and could make some suggestions.

I love this amp. I can't go back. It combined with JRiver MC has moved my music playback to level it has never been.

One thing I am considering is to go to a biamp setup in part to take the load off the single amp. That is a fall back in case I couldn't solve the cutting out problem.

Since ClassD seems to have gone mute I figure I need to solve it myself.

I must say that for a company that sells DIY stuff their support is really spotty. They make promises that they don't follow through on and go quiet for weeks at a time.

[Letitroll98]

Move it where ever you think it most appropriate. I was trying to see others were having this problem since was mentioned a couple of times in another thread. They had found solutions but those solutions didn't work for me. I was hoping someone else had my experience and could make some suggestions.

I love this amp. I can't go back. It combined with JRiver MC has moved my music playback to level it has never been.

One thing I am considering is to go to a biamp setup in part to take the load off the single amp. That is a fall back in case I couldn't solve the cutting out problem.

Since ClassD seems to have gone mute I figure I need to solve it myself.

I must say that for a company that sells DIY stuff their support is really spotty. They make promises that they don't follow through on and go quiet for weeks at a time.

Let's address this in the reverse order of your post quoted here.  classDaudio is a small company, one man as far as I can see, and neglected customer service is one of the first casualties when the business takes off like this one has.  Maybe Tom could do better, but you had to expect this if you read the $175 amp thread.  I mean, we're not dealing with AR, Krell, or even AVA here. 

Not sure if you mean bridged mono or biamped as in active crossover as a possible solution, but I can't see how this would solve the problem if it's in the module.  I note that you had a self inflicted problem with the amp previously and apparently that was solved, no mention of what was done for you there.  Perhaps some history of what's gone on with you and classDaudio before the silent treatment may enlighten the matter.  Other's seem to be getting replies promptly, just sayin'.  You also have posted about some pretty severe electrical gremlins in your home associated with some PS Audio products.  Could that have contributed to this problem in any way? 

I'm glad you like the sound of the amp, and I sympathize with you looking for an answer to your problem.  I really can't see how you could get more answers outside of the $175 amp thread, the question belongs there, and I foresee it being merged there pretty soon.  However in the interest of fairness to you let's leave it here for a bit to see if outside influences may help you.  But I do ask the negative comments stop, you made your point and asked the question about responses from cDa which was answered.  We can see you're upset and trying to be polite about it, but lets focus on solving your problem.  Best of luck.           

[mboxler]

I'll start with saying that I've had nothing but excellent service from Tom.  I recently purchased one of his new enclosures with components for my SDS-224, and received no instructions.  Within a day, Tom e-mailed me multiple pictures of the inside of a completed amp, which answered all my questions. 

Going thru your previous posts, it appears you are driving VMPS RM2's?  Is that correct?  According to Tom's website, the SDS-258's specs are 250w into 8ohms, but does not mention specs into 4 ohms or bridged.  Did Tom say this amp could drive a 4 ohm load, which I believe is the impedance of the RM2's?  Letitroll98 is right...we want to help if we can.

Mike

[Bill Baker]

it cuts out momentarily during some passages

You don't mention it but can we assume that this happens while playing at higher volume levels?

[Regalma]

At the suggestion of another member I contacted them through their contact address rather than replying to a personal email from Tom. I got an almost immediate reply.

It seems that he knows there is an issue with the circuit overheating and he is working on the design. That is why there has been a delay.

So I did get something from this post, the suggestion to not rely on replying to his emails.

[stigs]

 I have had this issue since purchasing  my SDS-254 on 07/15/10. I am driving a pair of Magnepan MMG speakers which have have a nominal 4 ohm load. I sent the amp back to Tom for testing and he said it checked out fine. I puchaced a second amp to biamp my speakers, thinking this would solve the issue. No such luck. On 01/01/12 I came across a post from a member named krikor written on page 149 of the big thread followed with pictures on page 151. Seems all this time the issue has been a thermal problem. I emailed Tom to purchase some of these heat sink outriggers and never got a reply.
 I decided to make my own by just picking up some bar stock from Home Depot. This did resolve the heat issue, however I didn't care for the look and decided to take it a step further. I ended up getting a Vantec HDC-502A hard disc drive cooler and bolted it to the top of the existing heat sink. I also bought a variable power supply from ElectonicKits.com and wired it to the unused taps of the transformer. This was simple to do. I can now control the fan speed to keep fan noise down or just turn down the voltage all the way to stop the fans for low level listening.
 Notice the outrigger heat sinks now on ClassDaudio home page picture. Obviously Tom is aware there is a problem and came up with this solution.

[Barry_NJ]

Please include any reasons it shouldn't be merged into the $175 amp thread.

Thnx,
Letitroll98
Facilitator

Hi, quick comment on the other thread. That thread was started about a particular amp kit, at a particular price point, from a particular manufacturer. Since then it has grown to include 6 or more different variants, at different price points and is rather difficult to follow. It wouldn't be so bad if the manufacturer had more complete info on his website, but that thread is my main source of info on his products and it isn't always clear which of the different modules is being discussed in a particular post. Myself, I wish that thread could be split into different threads, if not by board, at least by board series, CDA, SDS, and TI, as each series is supposed to offer different sound qualities, and even among the different, boards in a series there are variances in power delivery into more difficult loads, and sound quality. So that one monster thread becomes difficult to follow.

Regards, Barry

[Charles Xavier]

Hi, quick comment on the other thread. That thread was started about a particular amp kit, at a particular price point, from a particular manufacturer. Since then it has grown to include 6 or more different variants, at different price points and is rather difficult to follow. It wouldn't be so bad if the manufacturer had more complete info on his website, but that thread is my main source of info on his products and it isn't always clear which of the different modules is being discussed in a particular post. Myself, I wish that thread could be split into different threads, if not by board, at least by board series, CDA, SDS, and TI, as each series is supposed to offer different sound qualities, and even among the different, boards in a series there are variances in power delivery into more difficult loads, and sound quality. So that one monster thread becomes difficult to follow.

Regards, Barry

I like the way that it is.