Building AMP6-BASIC

[mmargeli]

Hi folks

one week ago, i built my very first amplifier, an amp6basic.
First of all kudos to the guys of 41Hz.com, the swedish and the austrian mail service who delivered my kit, two days after my payment was recieved. [:0] I'm deeply impressed.

I built the Amp that same evening in about three hours straight. The documentation proved to be excellent, and made building it really straightforward, easy and fun. One thing I noticed though, was that the newly introduced resistor in Rev. 1.1 seems to be alternately refered to as R3 and R8 and is not mentioned in the step-by-step instructions at all.

Another thing I had slight difficulties with, were the SMD diodes. Soldering them would be quite a lot easier, would they be placed in the early steps of completion. The way it is, I had trouble navigating the soldering iron and solder around the tall caps. Then again using 1,5mm solder and an iron presumably suitable for soldering pipe fittings, I'm probably not the one to talk...

Other than that I had no difficulties and I don't think a complete beginner using decent tools and enough time would have any either.

After the build I went on to testing. Using three 3R12 batteries in series, according to the instructions, I first tested the sleep current draw, got a reading of about 0,3mA and was happy. Then I connected signal and a speaker, jumpered awake and... blew the fuse of my multimeter. Ouch. Inrush current. Shoulda known better...

Still better the crappy meter, than the amp. Next I got very courageous, powered up the amp without any meter inbetween and voila... music!

The next day I continued testing using a 75W SMPS from my laptop computer, which boasted 16,5 volts output, as I found out later...
Did the amp no damage - lucky me...

With this setup, I listened to some tracks from my ipod and found out, that the gain was not quite high enough. May be due to the very weak output signal of the volume-limited Ipod nano. I'm planning to bridge the input resistors with some 100k, to get the input gain up to about 3V/V.

Regarding the sound I can't say much. I don't believe many people can hear the very subtle differences and insufficiences in amplifier sound over the comperatively enormous faults of even the very best loudspeakers. So how could I judge this amp playing through my crappy three inch wideband speakers. I can only state, that everything sounded like it should, plus the amp6 didn't suffer from the very quiet but annoying hum that I knew from my Onkyo main amplifier.

All in all I must say, that this amp is for sure one of the best spent EUR 40 in (my) recent memory and I'm already planning a dual mono AMP11 for replacement of my Onkyo. [8D]

regards
Martin

e: pictures will follow... be warned [8D]

[krilli]

congrats

[V-bro]

Great post!

It's an A-MA-ZING little amp isn't it?

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

[mmargeli]

said pictures (the heatsink of my old GeForce 2MX fits perfectly on the chip):





greetings

[alexlangberg]

Hi

I just finished building this too. I'm very glad it worked the first time. It's so satisfying to hear it play for the first time.

1) I totally agree on the diode thing. I'm not sure what the reason is to place them so late, I think they should be put in bag 2.

2) The gain resistors have apparently changed from 56K to 82K. I know that most people here probably know why but for a beginner it's quite frustrating to be looking for 56K resistors that aren't there. It does say in the instructions that the resistors are only "nominally" 56K but I think many beginners will be confused by this. I was.

3) I was using the PDF at first, where the jumper positions are not explained as far as I can tell. I think those should be updated or the links just replaced with the forum assembly instructions.

4) A small piece of paper with the color codes of all included resistors and their values would save beginners a LOT of time I think. They are so small and I had to use an online "translator" to get the values since I don't have my own chart.

5) It works great and only took a couple of hours to make. Thanks a lot for this great piece of kit!

Best,
Alex

[krilli]

Good points, alexlangberg

[V-bro]

said pictures (the heatsink of my old GeForce 2MX fits perfectly on the chip):



greetings

Do I see a Monacor SP-60 in that home made box?! That's an amazingly good sounding speaker for the price don't you find? And it's nearly impossible to over power it... I just LOVE them!!

[alexlangberg]

>> alexlangberg (and other/new builders)

Online AI (cannot change the pdf under Shop Downloads):
1) I put at start to do steps 1+2 of 'BAG 5' first
2) mentioned the possibility of 82k value
3) maybe better to always use/read/check AI on website.
4) maybe. but a DMM of 5 Euro can do wonders. better to check value anyway?
5) all thx go to Mr.41hz, JanAF, he'll appreciate it

If you prefer a locally stored pdf, you can always print the AI to/as a pdf-file, of course.

Super! You should probably also double check if there's a reason the order was like it was before. The online documentation is of course the best to use but when you buy an AMP6B, the e-mail order confirmation you get tells you that instructions are placed under shop downloads. Perhaps this should be changed as I just got the pdf right away and started working from it when I recieved the parts. It's not a huge problem really but it would be convenient.

[mr-busy]

Probably, it was based on the 'BAGS' nr. I think that's the basis thought behind the BAGS.
And in the future, those pdf-s will (probably) be replaced by the online AI.
So, I reaally try to keep those up-to-date/usable as good as I can.
But it's not always easy......I depend on input/feedback.
And of course only until I stop liking to do it. sometimes......

[alexlangberg]

Probably, it was based on the 'BAGS' nr. I think that's the basis thought behind the BAGS.
And in the future, those pdf-s will (probably) be replaced by the online AI.
So, I reaally try to keep those up-to-date/usable as good as I can.
But it's not always easy......I depend on input/feedback.
And of course only until I stop liking to do it. sometimes......

No problem, you guys are doing a great job, the quality of feedback from this forum is really great in general. I'm just trying to catch all the small things that beginners will be confused by, while I'm still a beginner myself.