Another F5 build--beautiful music, different drummer

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CanAm Man

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Joined 2006
Doug Kim said:
Hi CanAm Man,
1. Ac-0-AC: The seller suggested to use 12-15V AC, but why are there two AC's? Which one to use? Doug--the board is designed to use with a center-tapped transformer. Use one that has two windings (of 12-15 VAC) and a common center tap. Connect the center tap to the "0" terminal on the three-terminal block. The two other leads go to the "AC" terminals.

2. IN: I supposed this is where I connect the output (+) from the amp.... Yes. Connect the "hot" amp output to this terminal

3. POS and NEG: What are they and why are there multiple soldering spots for them? These markings on the board are a little misleading. The two POS terminals are the "hot" outputs to your speakers. You can either use the small soldering pad, if you are using wiring between this board and your speaker binding posts; or, you can use the larger soldering pad to mount directly on the binding post (i.e., the binding post can fit inside this large hole, and you can use the binding post nuts to tighten to the board).

The NEG terminals are used for the "speaker ground terminal". Run a wire from your F5 amp board ground (or the star ground) to the NEG hole (nearest the "SP Protector" label on the printed circuit board. Connect your speaker ground to either the other small NEG soldering pad (for a wire) or the large NEG pad (for a binding post connection).

I hope that helps. Let me see if I have a good pic.

As an aside, I did NOT use the AC inputs to these protector boards. I used the F5 power supply, run through a 15 VDC switching regulator. I removed the power diodes and on-board regulator from these protection boards (no longer needed). By tapping into the F5 power supply, I eliminated the need for another (small 15 VAC center tapped) transformer.
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CanAm Man

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Doug Kim said:
Hi CanAm Man,

I purchased a pair of speaker protector for my F5 project, getting the idea from your thread. It did not come with any instruction and I haven't received any reply from the seller yet. It would be great if you could help me out.


Doug
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Doug--see the picture of these protection PCBs, in my posting #32. The WHITE wires connected to these boards (one for each channel) are my F5 amp PCB ground "speaker outputs". The BLUE wires are my F5 amp PCB "hot speaker outputs). You'll also see (below the white and blue wires), short BLACK wires that I used as jumpers to connect the proection outputs to my speaker binding posts.

(You'll also notice I removed the AC power input terminal blocks, two diodes (on each board) and the on-board regulator from each proection PCB.
 
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CanAm Man

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It's a wrap.....! I'm hearing beautiful music.....

For those who have been following my F5 build thread, I'm declaring a successful completion as of this weekend.

I did go with powder coating on my front panel end plates, as shown.

I also (finally) calibrated the VU meter ballistics and sensitivity, as well as the settings for the clipping monitors and heatsink temp monitors. Had concerns about "releasing smoke" when I connected the VU and clipping drivers to the amp outputs, but it was all uneventful.

I've posted my final build pics under the "Pictures of your Pass DIY Amp" sticky thread. One last pic is posted here, FYI.

My thanks to all those who posted comments, thoughts, and opinions on this thread. I've appreciated the exchanges. Special thanks to Papa Pass for his exceptional (and simplistic) design, and to ZM for his official "fugly" rating of my amp....! :D
 

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CanAm Man

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bkdog said:
That's absolutely bloody fabulous! Looks gorgeous. I'd be interested to know if you ever clip it, or what the typical output power is in real use - so few of us ever really measure it.

Thanks for the great build-bk
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Thanks, back at ya.....!

As for the clipping level, right now I have them set (left and right channels, independently) at 19.4 volts peak. That's against 21.4 vdc + and - PSU rails. Admittedly, that's probably a little arbitrary for now, but when I lug the amp back downstairs into my testbench, I'm do more formal clipping tests (audio signal generator, THD analyzer, and 'scope) to tune the clipping monitors.

For now, if I run my pre-amp fairly high, I can get both clipping lights to flicker--but only at an "almost unconfortable listening level" from my old Sansui speakers. (Yup---building new speakers is on a future "to do" list....)
 
bbm3

bbm3

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CanAm Man said:
BB--thanks again for the kind words..... If you want to see those VU meters dance, drop by.....! Give me enough warning, and I'll take the Shelby Cobra clone out of storage for a drive! (Bring earplugs--not for the amp, but for the Cobra....!)
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Yes, Yes, and Yes.
I'll give you a call.
In the meantime give some thought to the future of your rolling R/C car chassis, (Serpent?). I am interested.

Talk soon,
-BB
 
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CanAm Man

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Dave......

I agree with you on the $$$$$. I bought my VU meters about 35 years ago, and paid $25 for them.

Even if this eBay meter had a VU scale on it, I just can't see spending 300 bucks for it.

I knew I had a "barn find" when I saw those meters in that surplus store 35 years ago--but I should have bought more than just two back then...! LOL.......
 
merlin2069er

merlin2069er

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Joined 2008
irfp9240

I pulled it out of my system, along with the fried R13 (47ohm 1/4 watt resistor).

And between gate & drain I read 23ohms -- I guess that's bad, because the new one is OL between gate & drain.

Hopefully nothing else is wrong with the unit. I'm going to mount the new one and try biasing it up again.
 
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