Sure Electronics Tripath boards?

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#321
Good but some back ground noise

Hi Guys,

I ordered 1 PCB on March 30 and received it 2 days ago so it took nearly 2 wks following my order, not bad.

The one I have are as follow;

Input voltage marked 9-14Vdc
PCB rev 1.2
Output inductors 15uH
I have removed R3 and R16 for the +2.5V bias (useless since they have input cap)

The schematics that comes with the PCB (on a small CD rom) shows the input cap as 2.2uF, I have no way to verify this with SMD components but the bass seems OK.

I had quite a bit of hiss (not 60Hz hum) coming from the woofer and tweeter even without the input not being connected or shorted to gnd.

I cleaned the PCB to remove some flux and it improved quite a bit but it is still slightly there. Anyone has a solution to make it dead quiet..any help would be appreciated since I have ordered another one last week 😉

Take care,
Eric
 
#324
Re: Hiss still there

e_fortier said:
Hi Mike,

The hiss (not 60Hz hum) is still there even when powered with a 9V battery

Regards,
Eric
Click to expand...


Sorry, I misread your previous post. 😱

I think people have also been getting hiss from the Sure 4 channel class D amp also, it's mainly when used with high sensitivity speakers...

I'm not really sure how to fix it, maybe replace the inductors with toroid types?
 
#325
RE: hiss

Did someone mention that removing/destroying c3 and c24 inductors on the 100w board would knock the hiss out drastically? I believe I saw that when I was combing through this thread.

Also, if you replaced some resisters with metal foil ones and replaced the capacitors in the audio path with some Panasonic FC caps (or other higher quality ones), wouldn't you go far to upgrade the signal path?
 
#328
It's fixed, decoupling cap missing.

I had a look at the Tripath spec sheet and they have a decoupling cap of 0.1uF between pin 8 and 9 or to make your life easier between pin8 and pin 1. This cap is not there on the Sure module ver 1.2.

It is not soldered yet but once in place it is dead as it can be, no hiss at all 😎

Thanks for the help,
Regards,
Eric
 
#329
I could be wrong, but looking at the circuit diagram, it seems to me that this capacitor is simply in parallel with C4, which is tied to pin 4, which is tied to pin 1, and, at the other end, tied to AGND?

Or is the distance of this bypass cap critical for it to work properly? I was just wondering, because mine has a little bit of hiss, and I wanted to try this mod, but I'm not comfortable with soldering straight to the chip.
 
#330
I'm not trilled either but give it a try without soldering it, just hold the 0.1uF with some long nose and connect the 0.1uF between pin 1 and 8.

I will try to solder it this week at work with some temp controlled soldering iron and a big magnifying glass. What I usually do with surface mount ( I hate this stuff) if solder on end and then glue it wright away, once solid I solder the other part.

I will keep you posted.

Eric
 
#331
Thought I would post a pic of some recent lunacy I have tried.

The big caps are Obligato 2.2uf oil caps (sound great) and I added 8800uf of rubicon caps on the power rail....this is just temporary, my SMPS has 8800uf of rubicons already and it seems unnecessary to have that much input capacitance, especially with my small box jordans that dont go under 90hz!!

An externally hosted image should be here but it was not working when we last tested it.
 
#334
My ears are telling me that to much capacitance kills the sound.
I'm using a Mini ATX power supply with 5.5A on the 12V rail. I was running it with two 2,200µF caps attached to the board terminals and it sounded pretty good. I then soldered two 2,200µF caps on the board, leaving the two on the terminals making a total of 8,800µF. It sounded like cr@p. the whole range seemed muted, no highs, and some of bass that I know is there was missing.
When I get home from work I'm going to try 3,300µF, but I've got a feeling that may be to low. Nothing ventured...
 
#335
Thats odd...could it be in relation to the power supply you are using?

The reason I ask is I added 5 2200uf Panasonics to mine and my PSU already has 5 2200uf rubicons on its output and there really has not been a large audible difference.

I don't know if the bass has changed any because my Jordans don't reproduce it in their tiny boxes.
 
#336
Power Rails help

In an attempt to add a Panasonic FM Capicitor 680uF to each power rails, I managed to snap off C27 out the board. The dislodged cap does not look salvageable. Any suggestion on how to remedy the missing cap? Can anyone suggest any good 100uf 16v Cap replacement I can order from digikey? Or now that it is off, any suggestions on upgrading to C27 and C31 (or all) to higher rated caps?
 
#337
Delay fixed

Hi,

I recently purchased 2 of these board and it took about 2 wks max to get here in Canada. I dealt twice with Sureelectronics2 and not with Sureelectronics. Looks like the '2' is important.

Hope this helps,

BTW, I taught I figured out the hiss issue but it is still there, has this been fixed by someone ? I have a constant hiss even when powered via a 9V battery and both input tied to gnd, looks like a few 0.1uF decoupling cap are required by where exactly is the question...

TIA,
Eric
 
#338
Re: Delay fixed

e_fortier said:
Hi,

I recently purchased 2 of these board and it took about 2 wks max to get here in Canada. I dealt twice with Sureelectronics2 and not with Sureelectronics. Looks like the '2' is important.

Hope this helps,

BTW, I taught I figured out the hiss issue but it is still there, has this been fixed by someone ? I have a constant hiss even when powered via a 9V battery and both input tied to gnd, looks like a few 0.1uF decoupling cap are required by where exactly is the question...

TIA,
Eric
Click to expand...

Hmmmm, 9V is getting very close to the minimum input voltage so maybe you need to raise it a little? (I run all my T-amps @ 13.4V) Don't know if this will solve the hiss though....
I've recently modded one of these and compared it to a stock version.
THERE IS A HUGE DIFFERENCE.
I completely bypassed the input stage with just a new input resistor soldered in close to the pins.... no hiss at all even with a larger feedback resistor to raise the gain. (stock does have hiss😉)
I would put a 100pf cap in there though to block out really high interference, ............between the pins and ground, but only if you disable the dc offset circuit..... otherwise leave it all well alone.
Also, look at your input cables and make sure they are shielded, this is where any interference is amplified.
good luck
Lee
 
#339
Recent changes?

Hi all

I only recently found this thread and worked through it.
Trying to familiarize myself with the things advised to do to the board (has this wiki ever come to life?) I noticed that the schematics given in Figure 2 of this
http://www.sureelectronics.net/pdfs/AA-AB012_Ver1.0_EN.pdf
already contain alterations of the nature suggested here.

E.g. C3 and C21 have been lowered to 100pF while in the diagram posted by audio1st I read them to be 100nF. At 100 pF I might forget to eliminate them.
C13 and C21 are raised to 2.2 mF (880nF) which happens to be the value audio1st suggested in his basic mod picture.

Has anyone recently received a board from sure and can check whether these changes are actually found on the board?

Thx
 
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