Sure 2x100..been working on it

[morris]

Been working on this amp. Did not do any mods on the board except the addition of a volume control, removal of the fan and replacing the heatsink. Please let me know If you see any glaring safety issue. Also on close up picture of a corner of the board, there is a ground symbol...how should I go about grounding this?-newbie question I know but I would rather be safe than fried.

[killersoundz]

That looks cool man. My only concern is are you putting a top on it? You're gonna have heat buildup in the case with no ventilation.

[morris]

That looks cool man. My only concern is are you putting a top on it? You're gonna have heat buildup in the case with no ventilation.

Thanks! This is my first attempt to assemble something like this. It does have a top cover with perforated metal on top. I will post more pics tomorrow since I was able to do more work on it. I just hope the Meanwell PSU is in good condition since it was "dropped" with a thud at my house by the nice postman. It works but who knows if its life expectancy is shortened by the "gentle" handling of the USPS person.

[50 watt head]

I think your fine curly-maple woodworking deserves a better-looking volume control knob

[benchtester]

...Also on close up picture of a corner of the board, there is a ground symbol...how should I go about grounding this?-newbie question I know but I would rather be safe than fried.

I am pretty sure that can be connected to the ground on the power supply, which in turn is connected to the ground on the plug. If there are any metal chassis parts that are not exposed to power, they should also be tied to the same ground on the power supply. (Although I have a Mean Well power supply and my chassis is grounded through the case of the power supply. Just check with an ohm meter.)

It gets confusing since one can also have a "signal ground" (outside of RCA jack) and one might have a separate ground for the output transistors. I would NOT connect these to the "chassis ground" or to the AC ground (unless it sounds better - of course).

I doubt you would get fried in any case; but grounding can make significant difference in the background noise. You may need to try different connection schemes to find the best.

[tomzarbo]

Looks good!

I agree with killer in that you'll need some ventilation. I think in order for something to really breathe, you'll need an intake of air from the bottom of the case, otherwise no real meaningful ventilation can take place. Can you drill some holes or put in a metal panel with perforations?

Did you dial the voltage up yet? I have a similar Meanwell clone PS and I dialed mine all the way up, 30 volts I think is what it went to. It will get you closer to the Sure amps rated output.

As far as grounding, yes, you do want to ground the amp. The amp I built had a metal chassis, and I grounded everything to it, amp board and power supply, and ground pin of my power cord.

Your case looks very nice, good craftsmanship.

Keep us posted with pics, please!

TomZ

[PWR RYD]

They silk screened that ground symbol next to the plated through hole to indicate that the plated hole and surrounding pad is electrically tied to the ground plane of the pcb. It doesn't mean you have to add another ground at that point. They just want to alert you that if you use a conductive screw and standoff you will be tying their ground to your chassis. You can confirm this using an ohmmeter and measuring from that hole to the connectors J4 and J7.

[morris]

I think your fine curly-maple woodworking deserves a better-looking volume control knob

Lol! I know I want a better looking knob. I actually wanted a 2" diameter knob but this cheap radioshack knob will have to do for now.

Tom-It does have vents on the bottom front as can be seen one of the pics. Maybe it is not enough, or maybe not.

I was able to do some more more wiring. Powered it. No smoke. Good sign. but no sound even when the PE 50K potentiometer was turned up! Sent shivers down my spine. Adjusted the dipswitch from all off to medium....its alive and sounds really clean and good! Time to listen and see if the heatsink get too hot for comfort.

[morris]

Been listening to the Sure tk2050 for about an hour now and it seems to me that the heatsink gets really warm. I think I will have to include a vent directly on top of the heatsink or just add the fan to it. No big deal to me.
Another concern is that it produces a moderately loud clicking sound after about two seconds when it is powered off. The sound seems to come from the tweeters. I am afraid it may blow my tweeters. Is that clicking sound normal? What can be done to remove it?

[J.Lee]

Excellent Morris..... provides those of us afraid to take one of these on with some confidence. Looking to hear more as it breaks in.

[Sydney]

... Another concern is that it produces a moderately loud clicking sound after about two seconds when it is powered off. The sound seems to come from the tweeters. I am afraid it may blow my tweeters. Is that clicking sound normal? What can be done to remove it?

A relay could probably tweaked to drop before the 2 sec point.

[morris]

A relay could probably tweaked to drop before the 2 sec point.

Where would this "relay" and how does one tweak it? Is this relay located in the meanwell power supply that was kindly dropped by the Mr.Postman? /

So I come from using a Lepai that has a thump when powered off to a tweeter clicking sound when powering off.

Thanks!

[Sydney]

This is an example:
Note it acts by "dropping" the connection between the amp and speaker.

from:
http://simpleelectronic.com/2010/05/...uit-diagram-1/

You could install a manual disconnect speaker switch - but you would have to remember to use it before power off.

Also:
http://sound.westhost.com/project33.htm

[Johnnycat]

Question on the grounding... I am using the same amp for my Steampunk build... it is an all wood enclosure, do I still need to ground it? I was planning on only using a 2 conductor for the PS (after all that is what is included with the PS)....

[Sydney]

Also on close up picture of a corner of the board, there is a ground symbol...how should I go about grounding this?-newbie question I know but I would rather be safe than fried.

Make another green wire with a ring terminal and secure it to the board's ground hole with bolt&nut, connect other end to the same point as other green wire - Plug ground ( as benchtester indicated in post 5).
Better still would probably be a common ground plane.

[morris]

Make another green wire with a ring terminal and secure it to the board's ground hole with bolt&nut, connect other end to the same point as other green wire - Plug ground ( as benchtester indicated in post 5).
Better still would probably be a common ground plane.

Thanks! Done it already and its making music. The sound is clean and more powerful than the lepai it is replacing.

I decided to disconnect the volume pot since my daughter likes to play with it and decided to use the computer to adjust the volume. One thing I noticed is the significant increase in loudness without the pot. My computer volume has to be dialed down a lot. The clicking sound when the amp is turned of is still there without the delay.

[tomzarbo]

Thanks! Done it already and its making music. The sound is clean and more powerful than the lepai it is replacing.

I decided to disconnect the volume pot since my daughter likes to play with it and decided to use the computer to adjust the volume. One thing I noticed is the significant increase in loudness without the pot. My computer volume has to be dialed down a lot. The clicking sound when the amp is turned of is still there without the delay.

Nice pic!

I put two switches on my amp case.



The left one is for the power supply and the right one is for the amp. I switch the power supply on first, then the amp, and reverse it when shutting down, I don't have any bumps/thumps on power on/off. I like switches and lights. Side note: the amp LED stays lit full power for about 5 seconds after flipping the switch, then slowly dims until it goes out. Spooky in a dark room

TomZ

[morris]

Nice pic!

I put two switches on my amp case.



The left one is for the power supply and the right one is for the amp. I switch the power supply on first, then the amp, and reverse it when shutting down, I don't have any bumps/thumps on power on/off. I like switches and lights. Side note: the amp LED stays lit full power for about 5 seconds after flipping the switch, then slowly dims until it goes out. Spooky in a dark room

TomZ

I like yours better! Lol! I decided not to put lights on the front of mine since I have two daughters that get attracted to lighted things, switches and knobs! I even have put grill on my speakers because of it. The only complaint I have with mine is the pop noise when powered off. Maybe I have a defective unit? Seems like the pop should not be happening.

[Steve]

The popping sound when you power down is probably caused by DC offset. You can adjust the offset with R16 and R35.Check the voltage at the output with a load connected and set it as close to 0 volts as possible.These pots are very touchy!!!

Steve

[MLS]

I dialed my meanwell power supply up but it only went up to 27.8 volt on my cheap DMM. I thought it was supposed to go up to 29 volts, but it could be my meter. I did not notice anything and dialed it back to 27 volts.