AMP7 picture thread

[V-bro]

I'm building an AMP7 for someone in the UK right now and shot some pics which I thought would be nice to post. It's got two 2x33V 500VA toroidal transformers (one for the positive and one for the negative rail), an NTC softstart with 48Vac bypass relay that closes over them when there's AC voltage coming from the transformer secondaries. I built a dual rectifier from MUR820 (to220 case) diodes (just like in PSU1-PS) and put some R/C network over the diodes to filter switching peaks from the diodes (just like in PSU1-PS) There are eight 10000uF 63Vdc RIFA caps in there in total.
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EDIT: original text:"I put a rectifier on the 5V regulator input so I just need Vac to feed it with directly from a transformer and the same is done with the VN10. This is just to try and see if this works out to be "silent" enough which I guess (hope) it will."

EDIT: Don't do this!! It gives a slight hum residue! You may try this with a larger bulk cap, but I would still not recommend it. You'd best apply some stable DC voltage here, but it doesn't have to be precisely 10V because there's a regulator circuit on the board. I used a half PSU1-VR board set to 12Vdc in the final rev. (see pics below)
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It's got a nice case with 10mm thick black front panel from modushop.biz and I salvaged a heatsink from an old sony monitor to place the amp on. This is a prototype AMP7 board, so not black but green.

I chose the lower supply voltage to keep the power just moderate as there is no need for 500W/ch violence... Plus this keeps the voltage safe for the 48V relay, although it wouldn't be hard to just use a dc relay that operates from a 60V rail of course...

The whole setup is not meant to be ultra audiophile, but just a plain and simple good and stable amp. (which I also hope will work out the way I planned...[8)])

Wish me luck![8D]




I would be most pleased to see your AMP7 build pics

------X-max. can be several meters on any driver, too bad it can be done only once...------

[kifysara]

Looks good V-bro!
I love the Modushop cases btw.. IMHO there is no other source like it for DIYers.
Good thing Italy is next to Greece..

Those RIFA caps are huge.. I'm still working out how I'll manage to fit my 22k ones into my amp's case!

[V-bro]

Thanks!

These cases are quite nice indeed, although I would prefer some thicker material for the bottom plate with such a heavyweight amp. It's steady enough, but just about...

The ventilation holes are also hardly necessary.

But I guess they do custom casing, so you can probably ask for thicker plating...

22K ones, yes they must be huuuge! [:0]

------X-max. can be several meters on any driver, too bad it can be done only once...------

[kifysara]

Yes, they can make anything you like. I'd rather not have ventilation holes either, esp with the new FETs, for EMI reasons as well.
As for the bottom, I always go for their pierced bases. They really help a lot and make the whole case sturdier.

[wadoka]

Wow! What a monster...

in a good way

[V-bro]

Thanks Wadoka!

It's alive and kicking by the way. Still have to do some more listening with some decent speakers though. It has been a long way getting this thing right, I blew up two rectifier bridges because my NTC softstart was wired up to the wrong relay contacts bypassing them all the time... I thought I had it right, but two contacts we're wired differently than usual in this relay. I found out by measuring over the NTC's and they were 0 ohms...

Just to be sure I replaced them for 35A bridges instead the regular 10A because theoretically these were too light anyway, although I am using lower rail voltage...

I was able to hear the sonic character of this amp roughly on my test speakers, it's EXPLOSIVE!!

Here are some pics:








------X-max. can be several meters on any driver, too bad it can be done only once...------

[kifysara]

Nice work Vbro!
You think the extra capacitance helps after all?
When planning my Truepath MkII I was torn between going with extra-HQ caps like Sikorel at 40.000uF or "just" HQ caps like the Rifa 169's at double the capacitance (80.000uF).
[Sikorel @ 80.000uF was simply way out budget]

[V-bro]

Thanks Kifysara! You may now understand why I haven't gotten back on your email yet...[8)]

I'm not sure it helps, still have some more measuring to do...

------X-max. can be several meters on any driver, too bad it can be done only once...------

[kifysara]

Cool! Let me know - though I'm gonna try my luck with a Redrock SMPS as well.

[V-bro]

Well some like a slim case, most laymen judge the amp quality by the weight and the amount and size of the -in this case "useless"- heatsinks... Well... in many cases at least overrated heatsinks...

I've done some listening today and am VERY impressed. I also had some nicer speakers at my disposal this time, I'd still like a head to head with my Truepath on these speakers to be sure where it stands.

My suspicion is that it's at least as good, of course this amp has a more beefed up power supply, but more components (and PCB) are more beefed up than a Truepath. The inductors for instance stayed much cooler than the stock Truepath inductors... Everything on this amp stays cool, it draws just 90mA per rail at idle!!!!! But I also suspect this amp is slightly more dynamic and live sounding even than Truepath (I know, dangerous remark.....until proven....which is impossible because it's my subjective experience)






------X-max. can be several meters on any driver, too bad it can be done only once...------