Paradisea Problem - Need Assistance Please

Captain Humble · « **on:** 3 Dec 2006, 12:18 am »

I received a Paradisea yesterday.
It generates a hum in my system that can be heard through my speakers.
The hum increases in volume as I increase the gain on the preamp.
The hum is the most noticeable from the midrange driver on both mains.
Though I can’t hear the hum over the music I know it’s there and I'd like to find a resolution.

I tried a cheater plug on the Paradisea Power Cord.
No luck.

I tried a Jenson Model CI-2RR ISO-MAX between the DAC & my Preamp.
No luck.

Either of the above solutions have always corrected ground loop issues in the past so at this point I’m wondering if this hum is indeed a ground loop issue or is something else going on.

I spoke with Gordy.
We tried the following:
1. Moved the DAC to the top of the wall unit. It is now more than a foot from the preamp.
2. Went to RCA out on the DAC instead of optical.
3. Put layers of tin foil under the DAC

Nothing works.

I’m going to take it to Gary Dodd’s house this week to see how it does in his system.
In the interim, if any of y’all have experienced this or have a solution your comments would be most welcome.

Thanks,
Jeff

tvad4 · « **Reply #1 on:** 3 Dec 2006, 12:33 am »

Swap in a different tube.

JoshK · « **Reply #2 on:** 3 Dec 2006, 12:44 am »

Strange, I would have thought the cheater plug or the ISOmax would have done it. That would have been if it was ground loop. You've eliminated ground loops. The hum is coupling to the signal.

It could be a DC offset problem. I have coupling caps on the output right?

Maybe the unit isn't working properly, but if you have a multimeter can you measure the DC voltage from the center to the outer part of the RCA connectors for each the L&R? The unit should be turned on, but no signal playing.

Another thing to try is take a pencil and press the eraser down on the tube when the music is playing or stopped.

Is the DAC point to point or is it PCB boards?

tvad4 · « **Reply #3 on:** 3 Dec 2006, 12:49 am »

Bad tubes cause hum. Swap in a different tube. Sometimes the simplest solutions are overlooked.

Also, be certain your Paradisea DAC is the source of the hum. Have you taken it out of your system completely and used a different source?

bpape · « **Reply #4 on:** 3 Dec 2006, 12:51 am »

The tube was my first thought too.

Bryan

Charles Calkins · « **Reply #5 on:** 3 Dec 2006, 12:55 am »

Try disconnecting the FM feed if you have one.

Charlie

GHM · « **Reply #6 on:** 3 Dec 2006, 12:56 am »

Quote from: JoshK on 3 Dec 2006, 12:44 am

Is the DAC point to point or is it PCB boards?

I believe it's a hole mounted PCB board.

JoshK · « **Reply #7 on:** 3 Dec 2006, 01:02 am »

yeah it could be a bad tube, it could be a loose ground connection somewhere inside the dac. Basically there is noise coupling to the signal somewhere in the DAC. Tube is a good possibility for how that happens.

NewBuyer · « **Reply #8 on:** 3 Dec 2006, 01:35 am »

One thing I can say for certain, is that if you are not able to fix the problem, Mhdt Labs will make it right one way or the other. They are one of the very best sellers to do business with, and will not rest until you are happy.

I hope you can find the fix for the problem though, it sounds very frustrating. Are the internal jumpers set correctly for your voltage? (I don't even know if it would work otherwise, this is just the only thing I can think of ATM...)

Gordy · « **Reply #9 on:** 3 Dec 2006, 04:06 am »

There is no hum without the dac in the system, so something new has been introduced to the system as a whole. Jeff does have a Tungsol tube on the way but, nothing until then. We also tried, in vain, lifting the amp ground and placing the Jensen between the pre and amp. The Dodd pre has no transformers correct? So trying a grounded mild steel shield under the unshielded Paradisea won't help either... Jeff's electrical service is a custom dedicated line, highly unlikely to have a faulty ground connection there.

LightFire · « **Reply #10 on:** 3 Dec 2006, 05:42 am »

Your new thingis the cause of your new probem. It looks like your new paradisea is not really of good quality. It is probably not propery shielded and/or grounded. It is also possible that is "generating and capturing it's own noise." In this case it can be manufacturing and/or design flaw. Return it to the seller, or make sure the manufature reapairs it for you.

Scott F. · « **Reply #11 on:** 3 Dec 2006, 05:56 am »

Quote from: LightFire on 3 Dec 2006, 05:42 am

...... your new paradisea is not really of good quality......... It is probably not propery shielded and/or grounded........It is also possible that is "generating and capturing it's own noise."................ In this case it can be manufacturing and/or design flaw.

Thats one helluva stretch. especially if you've never heard one, had one in your hands or even studied the schematic and architecture to see if there could be flaw.

LightFire · « **Reply #12 on:** 3 Dec 2006, 06:06 am »

Quote from: Scott F. on 3 Dec 2006, 05:56 am

Quote from: LightFire on 3 Dec 2006, 05:42 am
...... your new paradisea is not really of good quality......... It is probably not properly shielded and/or grounded........It is also possible that is "generating and capturing it's own noise."................ In this case it can be manufacturing and/or design flaw.

Thats one helluva stretch. especially if you've never heard one, had one in your hands or even studied the schematic and architecture to see if there could be flaw.

If I had "one in my hands" it would not be the same one he has in his hands. So manufacturing flaws should still count. It doesn't matter how "good" the "paradiseas" are. What counts is that he received one that is not working well.

The guy has a system that works fine. Introduces a new item and a new problem arrives. Isn't that obvious that the new item is causing the problem?!

GHM · « **Reply #13 on:** 3 Dec 2006, 12:51 pm »

Quote from: LightFire on 3 Dec 2006, 05:42 am

Your new thingis the cause of your new probem. It looks like your new paradisea is not really of good quality. It is probably not propery shielded and/or grounded. It is also possible that is "generating and capturing it's own noise." In this case it can be manufacturing and/or design flaw. Return it to the seller, or make sure the manufature reapairs it for you.

Lightfire..dude..where do you come up with this stuff? Maybe this particular Paradisea has an issue..I don't know? But to say it's not of good quality or flaw in design is ridiculous! Go to the manfactures EBay feedback..and find a flaw there?
I believe you've missed Scott's point!

You really need to have one in hand. There are plenty of companies that could take lessons on the layout of this Dac..it is very very good! Well above its price point that's for sure.

Captain Humble · « **Reply #14 on:** 3 Dec 2006, 12:54 pm »

My sincere thanks to those that responded.
AudioCircle is a fantastic resource and I truly appreciate the members that are always willing to help and those that maintain it.

Quote

Josh Said:
Strange, I would have thought the cheater plug or the ISOmax would have done it. That would have been if it was ground loop. You've eliminated ground loops. The hum is coupling to the signal.

I called Gordy after the cheater and the ISO-Max failed to solve the problem. We agree.

Quote

Josh Said:
It could be a DC offset problem. I have coupling caps on the output right? Sorry Josh.

What is DC offset?

Quote

Josh Said:
You have coupling caps on the output right?

I can’t answer that one. What should I look for so I can answer your question?

Quote

Josh Said:
Maybe the unit isn't working properly, but if you have a multimeter can you measure the DC voltage from the center to the outer part of the RCA connectors for each the L&R? The unit should be turned on, but no signal playing.

I don’t have one but I’m sure Gary Dodd does.

Quote

Josh Said:
Another thing to try is take a pencil and press the eraser down on the tube when the music is playing or stopped.

I tried that late last night. It may be my imagination, but I think that the hum was reduced slightly. Also it doesn’t appear to increase in volume quite as much when I increase the gain on the preamp.

Quote

Josh Said:
Is the DAC point to point or is it PCB boards?

PCB boards.

Quote

Tvad4 Said:
Bad tubes cause hum. Swap in a different tube. Sometimes the simplest solutions are overlooked.

If that’s the problem I’ll be one happy camper. As GHM pointed out I’m waiting for a Tong-Sol that I ordered. At this point I don’t have an extra tube to try. I'll wait for my Tung-Sol to arrive so I can try it before taking it to Gary's.

Quote

Tvad4 Said:
Also, be certain your Paradisea DAC is the source of the hum. Have you taken it out of your system completely and used a different source?

Yes, I did that before I called Gordy.

Quote

LightFire Said:
Your new thingis the cause of your new probem. It looks like your new paradisea is not really of good quality. It is probably not propery shielded and/or grounded. It is also possible that is "generating and capturing it's own noise." In this case it can be manufacturing and/or design flaw. Return it to the seller, or make sure the manufature reapairs it for you.

Thanks for the input and if all else fails I will return it for repair or a new one. I sincerely doubt it is a design issue. Many prominent / well respected AudioCircle members have purchased and endorsed this DAC. One of them has served as a mentor of mine since I got involved with this hobby. If it was indeed a design flaw I would think they would be having similar problems.

Quote

LightFire Said:
If I had "one in my hands" it would not be the same one he has in his hands. So manufacturing flaws should still count. It doesn't matter how "good" the "paradiseas" are. What counts is that he received one that is not working well.

Something may have gone wrong when it was built which isn’t a big deal if he stands behind his equipment. Or it could have been damaged in shipping. Asia is a long way from Carrollton, TX.

Quote

LightFire Said:
The guy has a system that works fine. Introduces a new item and a new problem arrives. Isn't that obvious that the new item is causing the problem?!

Absolutely, there is no doubt in my mind that the Paradisea is the problem.

Thanks again.
I'll keep y'all posted.
Jeff

NewBuyer · « **Reply #15 on:** 3 Dec 2006, 02:28 pm »

He stands behind his equipment. By the way Jeff, did you check the jumpers inside the unit for proper voltage setting. Again, I don't know if the unit would even operate at all if the jumpers were improperly set, but curiousity forces me to ask you this again...

Captain Humble · « **Reply #16 on:** 3 Dec 2006, 03:32 pm »

Quote from: NewBuyer on 3 Dec 2006, 02:28 pm

He stands behind his equipment. By the way Jeff, did you check the jumpers inside the unit for proper voltage setting. Again, I don't know if the unit would even operate at all if the jumpers were improperly set, but curiousity forces me to ask you this again...

NewBuyer,
I apologize for not addressing your question in my last post.

The end of that post made me think that it just wouldn't work at all if it was improperly set. Later today I'll have a look to see if I can find the jumpers and if the settings are labeled.

I have no concern about him standing behind his equipment. I assume that most people will always try to do the right thing until they prove otherwise. Fortunately taking this approach rarely backfires.

Thanks for the help.
Jeff

Asic81 · « **Reply #17 on:** 4 Dec 2006, 04:23 am »

Quote

Jeff said:
I received a Paradisea yesterday.
It generates a hum in my system that can be heard through my speakers.
The hum increases in volume as I increase the gain on the preamp.
The hum is the most noticeable from the midrange driver on both mains.
Though I can’t hear the hum over the music I know it’s there and I'd like to find a resolution.

Jeff
I also owned Paradisea for one week now, doing break-in and listen to music every evening with my tube preamp gain at around 9 to 10 o'clock. Today when I read your posted, I decided to test my Paradisea to see if it has hum problem that you mentioned. Interestingly, here is what I found.
Preamp Volume knob at 0 to 2.30 o'clock: No his, no hum
But the hum starting at 2.30 and increases in volume as I increase the gain on the preamp
With preamp gain set at max, I can hear the hum clearly from 8 ft.

I tried everything I can with no luck:
Paradisea draw power from direct electrical out let
Paradisea with Balance PS
Cheater plug
Move Paradisea away from other gears
Replaced tube (Tungsol, GE 5 stars ...)
Different cables

The hum go away if I turn Paradisea off or remove completely.

May be other Paradisea owners should test their unit, and feedback.

Dustin

Asic81 · « **Reply #18 on:** 4 Dec 2006, 04:34 am »

I never listen at volume past 12 o'clock any way, so its not a big deal for me. Just curious if this is normal.

Here is my Paradisea

woodsyi · « **Reply #19 on:** 4 Dec 2006, 04:45 am »

I have had no hiss at any level going on two weeks. Actually, I haven't tried over 110 dB but it is fine below that and I have been running it 24/7 -- one week with stock tube and the other with WE 396A.