Building my Stella Amp

Submitted by petey twofinger on Fri, 07/22/2011 - 00:54

i met J. thru another forum where i had shared video links to some mini battery powered guitar amps i had hacked together . eventually he contacted me and asked if i would build/test then share my feelings on his Stella amp kit . i have no formal training in electronics , but i have done my share of tinkering , hacking and mod-ing stuff over the years . my youtube channel sows a handful of the projects i have done over the last few years . i have been more active in this field due to suffering a back injury that leaves me with more time on my hands . the one thing that John asked was that i would be 100 percent honest in my evaluation , he wasn't looking for any false praise , so i have been brutally honest in my approach to this endeavor . i guess i would classify myself in the advanced beginner stage of this hobby . its really been more trial and error for me , and i have had my fair share of disappointments , failures , things exploding , i even sent a kit back for pro-assistance due to my mis-steps . my nickname here at home is "Mr. Reverse polarity" , i have a theme song for that as well .
This evening i finished the assembly stage of the amp . i tested it out with a few different speakers and power supply's . i can honestly say that the entire experience has been top rate , the product performs very well , and i would recommend this kit to ANYONE who is looking to venture into the exiting realm of diy guitar amping . for the price , especially comparing to what is available commercially and the other kits i have seen on youtube , the Stella amp is an excellent choice . here are some photo's taken during the build process . i plan on doing a video soon , but i still have to mount everything up in a nice chassis , so that will be coming soon . on to the photos :

the package arrived the next day , unscathed , everything was there as well . i was impressed by the quality of the pots
http://img855.imageshack.us/img855/6686/dsc01902640x480.jpg
the instructions featuring close up detailed color photographs leave nothing to the imagination .
http://img683.imageshack.us/img683/4370/dsc01904640x480.jpg
Stella has two chips , she comes with sockets for each chip . which is fantastic in case of a disaster , a trip to radio shack and a few dollars will get her back in action .
http://img713.imageshack.us/img713/2324/sdc11818640x480.jpg
Getting jiggy with my plumbers flux , dont try this at home !
http://img600.imageshack.us/img600/5668/sdc11819640x480.jpg
Technique ? who needs it !
http://img195.imageshack.us/img195/7823/sdc11822640x480.jpg
Wax on , wax OFF !
http://img546.imageshack.us/img546/9876/sdc11823640x480.jpg
Q-tips not included ...
http://img811.imageshack.us/img811/6131/sdc11824640x480.jpg
The resistor that is sitting higher is for the gain , i may end up using a slightly different value on this one
http://img6.imageshack.us/img6/4485/sdc11825640x480.jpg
You can really notice it ridin high here
http://img18.imageshack.us/img18/2648/sdc11826640x480.jpg
the layout isnt too crampt
http://img846.imageshack.us/img846/3694/sdc11827640x480.jpg
almost there , i took my time , it was a very smooth build . the photo instructions are a great idea .
http://img84.imageshack.us/img84/3554/sdc11828640x480.jpg
i used a larger than necessary gauge wire for the speaker output , or did i?
http://img801.imageshack.us/img801/6839/sdc11848640x427.jpg
I got the these shielded cables out of an old VCR , i like using them for inputs , and even for pots . they just look really neat , i think the shielding cant hurt either ...
http://img7.imageshack.us/img7/3351/sdc11849640x427.jpg
Stella has 3 pots , gain , trim , and volume
http://img16.imageshack.us/img16/2725/sdc11850640x427.jpg
See what i mean about those cables looking neat ? the kit actually came with some very nice rainbow wire , but i am saving that for my daughters .
http://img38.imageshack.us/img38/5748/sdc11851640x427.jpg
The board is totally pro , just a joy to work with something this well laid out . everything about it , the labeling , the size of the solder pads , it lent itself to a very clean final product .
http://img204.imageshack.us/img204/1702/sdc11854640x427.jpg
the only omission i saw on the board was here , the positive for the LED was not labeled . J. informed me (before shipping) this is not the case on later versions of the pcb . a quick continuity test with my meter showed me the top slot is positive , the bottom the ground .
http://img84.imageshack.us/img84/9113/sdc11860640x427.jpg
The long leg on an LED is always the + , i usually mark the neg side w/sharpie before cutting the leads
http://img42.imageshack.us/img42/1465/sdc11865640x427.jpg
I used one of those vcr cables for the LED , dont forget the shrink boot !
http://img835.imageshack.us/img835/2147/sdc11869640x427.jpg
My version is the external pot mount , it appears that the board has provisions to mount your pots directly on the pcb
http://img846.imageshack.us/img846/4723/sdc21852640x427.jpg

my initial quick testing although minimal was successful . i really don't have a decent speaker or a nice chassis here tonight . soon i will have a much more thorough review and a video as well . i am getting my hands on some speakers tomorrow , then its off on the hunt for a special enclosure . i was able to get a fantastic clean tone up to a good amount of distortion , way past overdrive tonight . although it was late and i didn't want to piss off the neighbors / wake up the kids .
It was a treat to have it fire up immediately , with no troubleshooting necessary , and what really impressed me was the clean tone . not to say the distortion was lacking . the down side with a lot of these designs is it is difficult to get a decent clean tone with mini guitar amps . my first impressions are not only is Stella a great value , she also seems to out-perform a lot of her competition . Good work J. i can honestly say it was a real pleasure build this kit . If i had actually purchased this product its safe to say i would feel that i had made the wisest choice with my mini amp kit money . now wait till i get it boxed up with a proper speaker ....

Member for

11 years 5 months

John

Fri, 07/22/2011 - 19:02

Cool Petey, this is great! I love the heat shrink job you did with the LED. Looking forward to seeing it all built and put in a cabinet.

I think I pointed that out in the instructions about the polarity of the LED, I should really just photoshop a little plus sign in the right spot. (There's only 3 more version 1.0 kits without the polarity marker, all the rest will have it.)

finished her up this evening , its a little late though so i will have to do more extensive testing at a more suitable hour . here are some more pics from the build :

i used stand offs to mount the pcb to the side of the chassis
http://img199.imageshack.us/img199/3390/rdc11873640x427.jpg
i had to bust out the forstener bits to counter sink for the dc input jack on the right. this is kind of a hassle / requires some skill so i dread doing this . thankfully the pots and jack included in the kit have LONG threads . normally i have to do this for almost every hole drilled . this saved me quite a bit of hassle . thanks J.
the hole on the left is for a switch i cut in to shut off the tweeter on the speaker (i know) . i recycled that switch from something i garbage picked ....
http://img828.imageshack.us/img828/6640/rdc11876640x427.jpg
i hit all four of our cigar store's to rustle up a 7 by 7 box large enough for the 6 inch speaker (thanks Ken and Nancy) . i should count myself lucky to have so many places to scrounge from, although i may just altogether stop going to two of these establishments, some employee's can be less than helpful at times .
http://img828.imageshack.us/img828/3350/rdc11885640x427.jpg
holy holes bat man , at least i didn't break a dozen drill bits like with the "metal amp" i built ! which reminds me i forgot all about my multi bit i just picked up !
http://img96.imageshack.us/img96/678/rdc11888640x427.jpg
the pcb sits on the right side towards the top , one of the screws was touching a ground point and then a resistor , have to find a screw that does not have a large useless built in washer . the joys of hacking .
http://img10.imageshack.us/img10/5672/sdc11892640x427.jpg
the speaker has a tweeter so i thought it would be nifty to cut in a kill switch for it . i did ohm both of them out separate and of course together . i got around 4 ohms in all 3 cases . i am guessing that cap acts as a "crossover" sending "just the proper" frequencies to the gaudy red tweeter on the sony "EXPLODE" . what a genius name for a speaker , thats some excellent marketing that sony has going on there . " i just picked up a pair of jensen smoked voice coils for the samurai "
http://img717.imageshack.us/img717/5032/sdc11893640x427.jpg
i googled "sony explode tweeter kill switch mod" and found this handy reference photo , thank goodness for google hackz !
http://img11.imageshack.us/img11/3844/sdc11895640x427.jpg
i have been trying to make my stuff look more presentable , instead of gilligan'ed , so i ran the led thru the top speaker screw hole , drilled out the bezel and hot glued that sucker right in there .
http://img694.imageshack.us/img694/4286/sdc11899640x427.jpg
hot glue , its the new duct tape .
http://img40.imageshack.us/img40/2188/sdc11900640x427.jpg
i ended up having to turn the board upside down . the cable length for the input was like a mm and a half short ! for every 99 things like that there is that 1% freak thing where the stuff accidentally lines up perfectly , and i say "i love it when a plan comes together" . i live for that , buts its a long wait (it'll happen for ya , keep hacking) .
http://img34.imageshack.us/img34/1332/sdc11902640x427.jpg
DC input , tweeter kill switch , level pot , i always call it volume , but i never went to engineering school so what do i know ?
http://img232.imageshack.us/img232/8606/sdc11903640x427.jpg
that telltale hot glue plug on the far left , thats were i forgot to use the forstener bit first for the DC input jack . those types of things get classified as character .
http://img850.imageshack.us/img850/4730/sdc11907640x427.jpg
the speaker really isn't really crooked , thats photographic distortion , ahem . (more character) . not sure if you can tell but i did finish the cigar box with a few coats of krylon quick dry acrylic clear . at 4 bucks a can it better dry quick , it seems wall mart discontinued their house brand of klear cote , at least at mine there was no trace of the 1.07 a can clear :(
http://img715.imageshack.us/img715/3783/sdc11909640x427.jpg
there she is , foxy lady !
http://img695.imageshack.us/img695/7373/sdc11924640x427.jpg

i did do a quick test with my cigar box guitar , and my Korean cort 45 . the clean tone is very clean , not a hint of break up at all , even when you play very hard , which is were Stella really stands out for me . many of the mini amps can not pull this trick off very well , Stella is a very clean lil lady . do not be fooled by the initial demure , she does have her dark side . crank up on the trim and gain and you will quickly find out what i am talking about . i was also struck by the LEVEL (thats volume for us home-schoolers) she can put out ! like they say a picture is worth a thousand words but a video is even better . stay tuned for that , coming soon "stella the hella loud mini amp" to a youtube url near you .
So i must say i have to tip my hat to Mr. Wilson , everything about this experience was pleasurable , i have struggled thru much more poorly documented kits before , only to be disappointed with the final product . i can honestly say out of the 6 mini amps i have built so far i will be definitely be implementing Stella into my remote rig . she is going to be the right half of a stereo pair which on the left will sit my modad ( a modified danelectro hodad) , unless the modad can not keep up , which i am afraid will be the case (look for that in the upcoming vidjoe) . then i am going to slap another Stella together , i still have another identical speaker sitting here ...

Thanks John , everything about this kit was top notch , the documentation really stood out as being very thorough , you left nothing to the imagination , which was nice . the amp what can i say , its excellent , but you already know that .

Member for

11 years 5 months

John

Tue, 07/26/2011 - 01:00

I'm glad everything went well! Tonight I just finished up putting my amp in a cigar box with a 4 inch speaker; it was the box that flew apart when I was cutting the speaker hole. I wood glued the thing back together last night and tonight I drilled the holes for the pots and hastily threw everything in the box for a trip to the Handmade Music Minnesota meetup. I showed off my little stella amp in one room while some guys were setting up SIX MONSTER SPEAKER CABINETS that some guy made. I did my little presentation and got out of there (had my 4yo in tow and didn't want her to get permanent hearing damage).

I'd never been to the handmade music thing before but it was awesome, I'm definitely going again. One guy had a Moog (didn't ask him which one), but I wasn't there long, I wanted to get out before the ridiculous noise began.

Anyway, I need a teeny screwdriver for the set screw on my knobs (my knobs look just like the ones you used) and I need to put an LED in and get new hinges for the box, and maybe some little rubber feet.

This was my first chance to play with it at 9 volts and I take back all of the negative things I said about it at 9 volts. It sounds great at 9 volts, but you have to crank it. If you power it with 4.5 volts it will start to break up at a much lower volume level so it's more suitable for playing when the baby is asleep.

Once I do the final finishing touches (everything is mounted in there with paper tape at the moment) I'll post something. I got pics through this whole build process.

Oh, almost forgot, I put a tillman preamp on the front of it, just built right in with no kill switch or anything. (Thank god it worked right the first time.) I ran my CBG through it and it still sounded like poop. I think it's the pickup that I used, it's not really a pickup and I probably put it in the wrong spot. Gotta figure out a way to put a mic on the sound hole.

I guess the tillman preamp might be amplifying the signal a bit so maybe the distortion characteristics I was digging so much will change, who knows.

I'm tired and this is getting rambly. Keep me updated!

as a matter of fact i didn't go for any distortion type tones when i had my cbg runnin on her . it too has a tillman pre . i will look into this soon . i am planning on doing some A/B testing with 9 vs 12 volts on her . from what i remember , at 12 it was super stable/quiet , like everything dimed , and she was hush hush quiet , surprisingly quiet , like hardy any hiss , this was really not what i expected . that was with my cort 45 plugged in , as soon as i unplugged it , with the cable still attached to her or not she started fussin (it got NOISY) .
anyway that diy music thing sounded like a real treat , maybe you could look into some ear protection for the lil guy . i always operated in the frame of mind to engage my kids in this sort of thing whenever feasible . it turned out well for me , both my girls haven't strayed to the darkside , i mean they don't have any pop music in their ipods , but they also haven't gone goth/emo/hipster/punk/black metal . my lil one (1 almost 13) has developed an obsession for the beatles/lennon . so i am currently lightly encouraging her towards progressive . if she is going to end up obsessing over music , i'd rather steer her towards something that will end up at jazz , rather than tatoos , or cutting , heh .
in the mean time its been crazy humid hot and stormy here . i dealt with 2 A/C units that pooped out , but managed to bring em both around . going to finish that up today , deal with some car issues , then the next thing is shooting some video , getting back to some fun playtime for daddy . her birthday is coming up soon so i am going to use that as a dead line to post the vid , seeing i will be working with her (guitar lessons) after the big day . when the weather lightens up we are going to be hitting some remote spots for outdoor jam sessions , featuring the latest member of the family stella .