new AMP9-B

[chris4916]

Hi,
Really impressive: I put the order mid of last week. Part sent the day after and received yesterday :)

This evening, I started assembly. AI looking straightforward, I didn't rush but followed it. Well, to make it short, it works but I would not write, as V-bro did "even for beginner"

Not that it's complex or even long but it's not that easy neither:
- overshoot clamping diodes are very tightly spaced. I know I'm getting old but it was a bit painful [:I]
- Soldering inductors are not easy neither: if you don't put it well aligned from the beginning, then moving it is difficult, again due to tight space

This aside, very few components + SMT make it quite fast to assemble.

To be honnest, I didn't try it yet (in the middle of the night, will my wife and childrens appreciate ? [}:)] ) but testing offset shows between 0.1 and 1mV (I didn't mount zener diodes)

More feedback after "real" tests

Christian

I've replaced 3*3.3µF missing caps. with 3*2.2µF. I'll let you know...

[V-bro]

Hi, I'm sorry, maybe I've grown too experienced...[:I] But I do like to call upon the metaphore of sitting upside down in your car complaining car driving is really hard....no wonder...[:o)]

You have to think about how you're gonna do things before you really do with building amps. Than it will be dead easy doing the job for real....

The 2,2uF will most likely do fine, but Jan did put very high quality Panasonic caps in and he'll send you the right ones for free...

Replacing them again reminds me of a quote from the assembly instructions:
"Work slowly. Do not rush! Think twice and double-check before soldering!
Fixing a mistake is often very time consuming and can be very frustrating!"

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

[chris4916]

quote:Originally posted by V-bro
.../...You have to think about how you're gonna do things before you really do with building amps. Than it will be dead easy doing the job for real....

Correct, assuming you understand the very detail and clearly perceive, while thinking about how you're gonna do, what could be any single problem. Well, building AMP9B it was not a nightmare. If I had to compare, I would say that AMP5 was easier, much more easier, also because AMP5 assembly instructions have more details; another aspect that has to be taken in aco****: AI for AMP9B are very short and everything looks straightforward, which doesn't help, at least from my standpoint, at investigating the vey detail [:I]

And definitely, soldering tight SMT is not easy. From this standpoint, Truepath was less tricky.


quote:The 2,2uF will most likely do fine, but Jan did put very high quality Panasonic caps in and he'll send you the right ones for free...

Yep, I received related message. I will most likely ask for replacement caps to be put within next shipment (another AMP9B ? Who knows [?]) but asking for only 3 caps to be sent while some almost equivalent parts were available at home is a waste of money, even it it's no mine, don't you think so ?

Cheers,

Christian

[Xspunge]

Since I too built the Amp 9Basic, I will suggest that you solder the 4 Inductors BEFORE you add the speaker outputs and the 3 caps/1 resistor per inductor. The instructions say to solder those blocks, caps and resistors on first, bit if you do so, it only makes the inductors a little more difficult due to the close proximity to their solder pads.

An easy way to do the inductors (and this goes for any 41hz amp with the block inductors) is to tin the pads on the PCB with some solder first. Then just place the inductor over the pad, place the soldering iron on the pad/inductor lead and watch the solder flow onto both. Repeat until done and it makes it very quick and easy.

I think pretty much everyone will have an issue with the Schottky diodes on the bottom. Still, the amp will work if they are bridged so no one should have a heart attack if you cannot solder them on without bridging them.

While waiting for the 3 missing caps to arrive, I too could not wait so I tried to find some substitutes. I got 3.3uF caps, but they all have different voltage ratings from 100v to 200v. Well, for only .49 each, I figured I could try them out while waiting for the smaller ones. They aren't mounted close to the board so I can just clip them off. Its pretty much for testing only, so sound quality isn't an issue.

I too didn't bother to mount the 8 zienner diodes either, and I haven't mounted the LED's, only the mute and on/off switches.

The amp itself wasn't very difficult, and other than the 16 Schottky diodes will go pretty quickly if you've done any 41hz amps before. For those that have not built an amp before, just take your time like V-Bro said.

[PoloGTI]

Are there any tips on how to solder the 16 schottky diodes? The first row and the outer pads of the second row aren't a real problem, but the "inner" pads of the second row are. I can't even put my iron in between because then i'm only burning plastic of the first row, and my iron is quite small (Weller mini). Everything else went OK, but i'm stuck on this part.

update: just connected it to 12V and it isn't working. Fuse doesn't blow but the speaker outputs are measuring 0.5V.

[V-bro]

Pre-heating may help...

I first add solder to the PCB, one pad for each component. (this is generally a good way to go...)
I always make sure that there's no solder on the other pad(s) of one component, when there is I suck it away with desolder braid.

Than I solder the first diode on one end, after soldering the other end I add enough solder and keep it hot and solder the other diode that is in line immediately against it. Than I solder the outer pad that is still unsoldered.

I think it is not handy to start with the outer pads, when you did I would advise to desolder one row. Than add another bit of solder to the pad where the join and place the diode that comes in-line with the other....

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

[PoloGTI]

Ordered another Amp 9Basic because I couldn't get the first one to work, finished it today and it is actually working. Really impressed by the sound quality and very happy the second one did work out OK! [8D]

[y8s]

Just completed amp9basic and it sings. For the same reason as everyone else, I haven't had a chance to play it wide open. Too late!

Definitely easier than Amp 10 basic and Amp 4. The instructions could use some tweaks for order of assembly, but otherwise it's very straight forward.

At first I couldn't get it to work. No faults or anything, but no sound. Easy fix though: I had left out the input diodes and along with them, the charge pump diodes! Put those two in and there it was. :)

Matt

[y8s]

Just completed amp9basic number two minus the missing 3.3uF caps. Truly an easy build--did it in just a few hours without rushing.

I started with the 16 diodes and then did the inductors and it was much easier--following the instructions had me melting the output terminals.

Matt

[audiosteve]

Can any one tell me what type of power supply is required for the AMP-9 basic. I would like to run it at 24V but am not sure how much current my PS must source. Is 5A enough?

Thanks,
Steve

Nihlism is best done by professionals

[chris4916]

quote:Originally posted by audiosteve

Can any one tell me what type of power supply is required for the AMP-9 basic. I would like to run it at 24V but am not sure how much current my PS must source. Is 5A enough?

Well, it depends how loud you want to play it.
I performed some tests with 135W smps and was quite happy at low and medium level but was a bit frustrated trying to play it loud.
Then I moved to 400W 24v smps. Improvement was obvious even at medium level with deeper bass and less distro while playing "quite" loud.
Then I think I broke my AMP9 yesterday... for another reason

24v 5A delivers almost 120W, which is obviously not enough if you want to deliver... 4x100W :-)

Christian

[y8s]

the amp is rated at 4x100W so at 24V that would be 16.7A maximum but realistically you dont need that much.

You can use the 5A supply but it would be on the low end and you can't expect to drive the amp to full power.

[V-bro]

It all depends upon the peak capabilities of your supply, most musical signal makes your amp draw 1/10 of the rated power. Some very intense musical signal may make it draw more, still 5A would in most cases be enough.


The AMP9 is said to draw 40A peaks, but on average 11A at max. power. But that's with a sinus wave...

I use the amp on 12V most of the times, than 8A is more than enough...

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

[Saturnus]

Please also keep in mind that recorded original music is almost always mixed to the RIAA standard which dictates an average music level at -12dB, only peaks will be 0db meaning full power. The maximum average output level of an amp is therefore one-fourth of the rated maximum when playing actual music, and not sine waves.

So a power supply with a 5A rating is more than adequite provided it's peak output is high enough but off course big ass caps can provide that even if the power supply in itself can't.

[V-bro]

quote:Originally posted by Saturnus



but off course big ass caps can provide that even if the power supply in itself can't.



Exactly, only the 9-B doesn't have really big caps, only two 1800uF...

When you're on a PSU you'd do good to add a few more caps...

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

[audiosteve]

Thank you for all the great answers! I usually don't listen to music loud. This is for my office stereo so maximum peak current will not be required. But I'd rather overbuild than under build so I will find something closer to 10A just to be sure the PS is not overworked if I decide to crank up the volume a bit. Thanks again for all the great input on this topic

Nihlism is best done by professionals

[col]

Hi,

I'm new to 41hz kits. Received my amp9-basics a few days ago and have just got around to making a start on them. Was wondering if anyone has any high res photos of the bottom with diodes attached? I can't work out which way they go from any of the pictures in the forums (not high res enough). In the faq I read "white line goes towards the end with the cut off corners" but there is no cut off corners? Any help appreciated.

cheers,
col.

[col]

hmm.. think I have got it from the schematic now, thanks.

[chris4916]

Does it help ?
http://christian.bonato.free.fr/Christian/41hz/AMP9/img_1014.jpg

If you look carefully at the very border of diodes, you will notice a white line. On my AMP9B, this line is oriented toward yellow capacitors on top of picture, just like it's shown on AI.
What could be (very slightly only) confusing is that white line is not printed like on AI but at the very border of components. No cut off corner on mines.

Christian

[col]

yes, that helped thanks. hmmm... one of my amp9-basic kits has R6 and R8 missing.

col.

[col]

opps, sorry, I just found the resistors on the floor!

col.