Okay, I had a look under the hood, and it looks like it has the regulator circuit on the board. I drew a little schematic of what I saw and am attaching it to this post. Looks like the regulator is an LM317. If need be I can track down a datasheet for this chip, but if you know off the top of your head what voltage I can apply to it, that would be awesome! The battery is labeled UB1213, which google tells me is a 12v, 1.2Ah SLA.

Cheers,

DDC

PS, I'm also attaching a "gut shot" of the whole board. I can't read the name of the amplifier IC, but judging by the size of the heatsink, it's probably a class D chip. Looks like the preamp is built around a TL082 opamp

Thanks! I'll have a look "under the hood" this evening, and let you know what i find!

Thanks JM, that's really helpful! I'll probably try to the crocodile clip method for now, as I know the battery is getting near the "dangerously low" level and I don't want sulfation to occur!  The previous owner said that it had been "several months" since it had been charged. It wasn't totally drained, as I could still play it a bit, but there was some oscillation occuring, which the manual says occurs when the battery is really drained. The manual hints that the unit has a "smart charger". Does that make any difference in terms of the type of transformer I need to use? Is this why you added the edit to recommend a 20v DC 1A charger?

Cheers,

DDC

Hi all! I just picked up a Pyp PB-1 (http://pyp-bomb.com/home.html) for cheap ($40) in a craigslist deal, but the only catch was that the guy had lost the wall wart adapter needed to charge the damn thing! So, I was hoping one of you lovely people might own one and could tell me the specs on the charger? I looked on the website and in the manual, and it seems they don't list the specs anywhere. I also sent an e-mail to the Pyp Bomb people, but haven't gotten a response. So, you guys are my only hope!

FWIW, I've got an adapter that charges my spotlight, which is also powered by a 12v sealed lead acid battery. The specs on that wall wart are 12v, 300 Ma, center negative. The barrel plug fits the power jack on the back of the PB-1, but I'd like to confirm that the specs match before giving it a try!

Thanks for any help you can give!

Oh, cool! Thanks, I didn't realize that... Okay, so we will need 10 NiMh's for 13v to run our hypothetical battery amp. Good to know!

Actually, and somewhat ironically, just after I posted my last post, I went over to craigslist and noticed someone selling a Pyp PB-1 (http://pyp-bomb.com/home.html) for $40 (they sell new for $150), so I snatched it up! The ironic part is that it's powered by a SLA battery! 

Of course, he was selling it so cheap because he had lost the wall wart adapter, and couldn't charge it. Now I need to find the specs for the missing wall wart so I can charge the sucker up (I'll start a new thread)! But the little bit of playing time that was left in it, was enough to convince me that this amp will really do the trick for me...

Thanks for the detailed response! That all makes perfect common sense. Thanks for clearing up the efficiency of class D versus others in terms of battery life. 30% extra battery life actually seems pretty good to me, though! That could be a few extra bills in the tip jar, ya know?!?

RE: NiMh's... The price ratio for NiMh batteries is quite a lot lower here in the states than for you down in Brazil. You can find name brand (energizer, duracell, sony, etc.) NiMh AA's for around $5 for a 4-pack if you shop at the right places, and decent chargers for around the $10 mark. So it's not SO outrageous. The cheapest decent 12 SLA batteries I can find locally have 5 AH ratings and cost about $15, plus still another $15 for the chargers... 7.5 AH rated SLA's go for about $25. So you are correct that SLA is still cheaper, but the margins are slimmer here in the states. Okay, so for fun (!), let's do some math to see what we could do with each battery for an equivalent perfmance:

So, if i can get good NiMh's for around $5 / 4, that's about $1.25 a cell. NiMh AA's run at 1.3v, so to get "12" volts you need 9 in series (9 x 1.3v = 11.7v). The ones I have (energizers) are rated for 2500MaH, so 9 batts should keep a 30watt tripath chip powered on full for at least an hour (which probably means closer to 1.5 hrs with real usage). This is 9 * 1.25 = $11.25, so we are getting real close to our SLA budget, and yes, this isn't really long enough to do much with. So, if we add a second array of 9 series NiMh AA's would up the MaH rating to 5, allowing for 2 hours straight playing at full volume (and perhaps even 3 hours of "normal" usage). While perhaps still a bit on the short side, I think we're finally getting into a decent range of use-time. SO, those 18 cells cost us 18 * 1.25 = $22.50. Let's add in the chargers: $10 for the NiMh, or $15 for the SLA charger. Okay, let's do the totals! $15 + $15 = $30 for the SLA, and $22.5 + $10 = $32.5 for the NiMh. This is interesting! For a couple of dollars more, you should get simialr performance at a fraction of the weight. What about that $25 7.5 AH SLA? Totals are: $25 + $15 = $40 for the SLA system. $33.75 + $10 = $43.75. Still about the same price margin.

Okay, let's look at other factors: It's definitely a pain that you can only charge 4 NiMh's at a time. For our 18 batts, that would mean you have to charge in 5 rounds!!! That sucks. For another $10, you can get a second charger and now do 8 at time. That's still at least 3 rounds... BUT, my NiMh charger takes only about 2-3 hours to charge up 4 cells. I think SLA chargers need like 6 or 7 hours usually, so although you have to be more proactive with the NiMh, if you have two chargers (or one that can take 8 batts), it's about the same charge time total. So now our price margin is not as slim. We've got about $15 more into the NiMh system at this point.

So, what to choose? My main reason for wanting to go with NiMh (or other standard small cell rechargeables) is for the weight reduction. SLA batteries are HEAVY man! And for a portable rig, I think it's probably worth the extra $15 or so to keep the weight down... Also, from what I understand, an advantage of NiMh is that they don't experience much voltage drop with use (ie, they stay pretty much at 1.3v throughout discharge), unlike alkalines that do drop voltage with use. The result is that performance doesn't decrease until the battery is basically drained (ie., no "low battery" syndrome). How does that compare with SLA? Do they drop voltage as they get discharged? If true, this could be another reason to use NiMh...

Anyway, it seems that either way, you are going to have to drop about $30-$40 just on the battery and charger system to build a battery powered amp that can hang for a few hours playing time at 30 watts. Now, if you decide to drop some power, and go down to, say, 15 watts (still pretty good for playing on the street), you can get double your playing time. In that case, you could potentially get at least 2 hours (potentially 3) out of your 9 2500 MaH NiMh's, and you'd only need to spend about $25. in any case, I've already got enough NiMh's to do the 9 battery configuration, and it's not TOO much of a pain to charge them using my one 4-batt charger. If I buy this amp module http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-385, I'll wire it up in dual mono as a PA, which means that if I only use one channel, I'm hoping I can get close to that 2-hours plus of battery life. The module costs only $15, and I've got an enclosure already built, which means that the most expensive piece of equipment will be the speaker. Just because I'm super cheap, and to keep this a super budget rig, I'm considering to use this low cost 10" driver (also from parts express so I can combine shipping with the amp module): http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-262. So, in terms of actual cost: I will be looking at about a $35 to $40 pay out after shipping costs. If I needed to buy everything, I could expect to spend probably about $70-$80, depending upon the enclosure. Comparable wattage commercial battery amps (like the taxi) are in the $160 range, so still a pretty good value! I have no idea about what it will sound like though! 

@JMFahey: What class of chip amp were you trying to power? The reason I ask is that I've been lead to believe that class D (or T) chips are efficient enough to run off of low amp-hour batteries, but I have no direct experience with them. I don't need super high wattage, just enough to get heard on the street. I used to use NiMh's in my little pignose (which I've since sold on, since it was a one trick pony), and it was plenty loud at around 5W. It was one of the older discreet circuit ones too, but I still got several hours out it on a single set of NiMh's.

@gbono: Yeah, batteries ain't cheap! I looked up these new Lithium Ion batts he's using, and it looks like you can get a 12v pack for in the $30 range, which is similar to 12v SLA batts, but WAY less heavy (which is primo for a portable amp). The thing that always takes the price over the edge is the charger. You have to add on another $20 to $50 dollars for the damn charger! This is why I'm so keen to use NiMh. I've got tons of those already and a great charger. I use them in my cameras and other portable electronics.

Yeah, sorry. Mistyped. Actually, I'm considering to build a class D, as I kinda want a battery powered PA. The tripath chips can provide very decent output with single rail 12v power. I was looking at one kit for 2 x 15 watt stereo set up that claimed 2 amp peak current draw http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-308. If that's the case, you could even power a PA with rechargeable NiMh AA's and get at least an hour and a half of run time. Making that PA would be super easy, and the kit i was looking at is only $22. Couple it with a DSP pedal and you are good to go!

EDIT: This guy beat me to it! http://www.harmonycentral.com/docs/DOC-1833 This is EXACTLY the kind of rig I'm thinking about building. Super portable and GREAT sound!

I use my DSP pedal (a digitech RP unit) in small venues (like coffee houses), but I usually play out on the streets (I'm more of a busker than anything else). I use it with a small 20 watt PA (an old Realistic brand 2-channel with discreet transistors) at what I would call "reasonable" sound levels (i.e., no need for ear plugs, but loud enough to be heard in the back of the room). However, I'm a one-man band, so I don't have to compete with anyone else's (too) loud amplifiers. I use this set up to play both amplified harmonica and cigar box guitar. I love it because I have a range of tones at my fingertips (toes?) and I don't have to cart around a ton of equipment. I will say that my old PA doesn't stay clean enough at the volume that I need, and it starts to color the tone from my RP unit. This is one reason I'm considering to convert my more powerful lm-3885 amp to be basically a clean PA. I don't need extra volume, I just would like a bit more clean headroom.

fwiw, I totally agree that you have to program the unit at full volume. When I first got it, I made some patches that sounded great at home, but as soon as I plugged in an turned up, it was feedback city and bad tone. Instead of giving up, however, I tweaked. I soon realized that I just hadn't set up the damn unit correct. Also, I realized that I needed to re-tweak for EVERY different microphone I wanted to use with it. Settings that sound amazing with my stick mic sound like *s!!t* with my bullet, or with my bicuit mic, and vice versa.

Hi all....  I was just checking back in on this forum after a long absence and saw this thread. I thought i'd post because the reason I've been away so long is that I bought my first DSP amp simulator, and my quest for good quality sound at a low price was over! So I guess you'd call me a "believer" in amp modelers, but I do want to stress that I fully agree that they may not sound *exactly* like the amps they are trying to simulate. Not being an amp purist to begin with, this has never bothered me. To me, if it sounds good, then it is good, and my little RP unit sounds great to my ears! Personally, I think a lot of the bad rap these kinds of units get is from folks who bought them expecting a panacea, but never took the time to figure out how the things work, and never took the time to get all the levels set and their patches in good working order.

BTW, now that I'm a DSP guy (for tone), I'm now into SS amps even MORE than I was before. Only now my quest is simply for a nice clean amp to make my tone louder! I'm thinking about totally redoing my lm3885 amp with a nice clean buffer in place of the dirty little preamp I have in there, and then building a nice 2 way speaker cab to go along with it... It would be ideal to have this battery powered (at the cost of some output capacity) so I can take my show on the road (litterally).

Cheers,

DDC

I just bought a used Jay Turser Classic 10 amp which uses the tda2030 as the power amp stage. (http://www.jayturser.com/classic-10.php). It sounds REMARKABLY good for an amp that only costs ~$80 new, and which I bought used for only $35. I have not traced the circuit, but merely looked at the component side of the board (see gut shot below). Preamp stage is a single FET front end (J103) followed with a 4558P opamp. There seems to be two red LED's in this stage, most probably for clipping. The preamp stage has one gain control, and a "higain" switch. IMO, the higain switch is pretty useless, as it doesn't change the voice of the distortion, but rather just bumps the gain in the first stage. This means that it's the same tone, but just that you can use a smaller sweep of the gain pot before feedback. There is a no-name transistor (it's marked with a number, and then "Ge", so possibly a germanium?) after the opamp, probably used as a gain stage to follows the very effective but also very interactive triple band tone control section. After this, there is the master volume control that goes straight into TDA 2030 power amp stage. The amp uses a 6" 4ohm no-name speaker.

This amp is dual powered. Either straight in from AC (discreet diode full wave rectified single rail ps to +12v, with 2200uf cap to filter), or direct from onboard rechargeable 12v battery pack (probably NiCad, but maybe NiMh. I didn't open the battery pack to confirm). The battery charges when amp is plugged into AC.

Component quality is pretty good too. 1/8watt carbon film resistors in the signal chain, 10watt metal film ones in the PS. Mostly Poly film caps (the green ones) in the signal chain, but a few ceramic in low values (eg 0.001 uf and lower). Decent run-of-the-mill electrolytic can caps in the PS and elsewhere. Could have a little bit more filtering in the PS, but the amp is very low noise as it is, so I'm not too worried about that. A very low hum is only audible with the gain and volume cranked. Plastic jacks for input and headphone out, but that does not bother me as they are all mounted very securely. There's little worry of breaking them. Plenty of heatsink for the chip (a mediumish aluminum heatsink that is also thermally coupled to the larger steel chassis). The electronics are housed in a really nice steel chassis, so no worries over interference. The transformer could be bigger, and it is a standard iron lump (ie. not a toroidal), but seems to be quite adequate. I have no idea what the VA rating is, however. The cab is pretty well constructed, and is a combination of solid wood (for the front and internal supports) and particle board (sides and back). It's VERY cool looking, with the inlaid wood frontplate and the tweed covering on all other sides. Battery life seems good. I played it for a couple of hours on battery life, and it showed no signs of draining. Probably 3 hours will be the max bat life. One could potentially increase this by building a custom battery pack to increase the AmpHour rating. Probably have to stick to NiCad (or NiMh if it's that), and not lead acid, as the charging circuits are sure to be different.

This amp sounds VERY good. Plenty of tonal variety, good volume output for only 12v power (it claims 10w, but probably more like 6-7 as JMFahey says), and the no-name 6inch speaker sounds surprisingly good! It actually puts out respectable levels of bass! One could definitely fit in an 8"speaker in the space available, and that could potentially increase volume output and improve the tone a bit, but the stock speaker sounds pretty damn good! I bought it for busking, and I think it sounds WAY better than the Legendary Pignose I used to own, or the Roland Microcube I was also considering to buy. I'll be mainly playing harp through it, but it also sounded really good with my Cigar Box Guitar, which has a homemade single coil pickup in it. You can get quite clean (although only at a notably lower volume), and you can get ridiculously dirty (metalish). This amp is best at a nice overdrive tone (bluesy). At this setting, you can get deep and dark by cranking bass and dialing down the treble and mids, or you can get bright and cutting by dialing down the bass and uping the trebel and mids. Very different tones, but all at the same gain/volume level.

Overall, I think that if you are thinking of making an amp on the 2030, you'll be better off buying this amp and modifying it. The chassis alone is worth the money, plus you'll be getting the tranny, the power supply, the battery, the pots, the jacks, etc... Having built several chipamps completely from scratch now, I think that finding a good pre-fabbed amp, and modifying the circuit a bit (ie. changing or adding components to the preamp and tone control stages) is the best way to go.

Possible mods are 1) upgrading the tranny. 2) upgrading battery pack 3) changing what the "higain" switch does 4)changing the voicing of the preamp section (need to trace the circuit first) 4) changing out the speaker 5)adding a speaker out jack to run  bigger cab. But the amp sounds quite good stock anyway, so even these things would be mostly just for "fun".


Here's a gut shot:

The Digitech RP series have a good Leslie model. I use the $90 RP 155, and I love it. It's DSP, but it's so good, you wouldn't care even if you were the biggest Analog Snob in the world. If you go that route, you get a lot more bang for your buck than if you bought a single purpose pedal. As for single purpose leslie simulator pedals, I've heard good things about that cheap-o danelectro one (can't remember the name of it).

Thanks JM, that's a good idea. I'll build a box 8.5" square, by 4" deep for the speaker, with the speaker facing down. I'll stick the PCB in this box too, with control pot/switch sticking out the side. I have the little rubber screw-on feet that I can use to keep the speaker opening off the floor. I'll attach the trigger pedal with a gate hinge off one side so that it will extend out with a slight angle to rest on the ground, and can be folded down across the speaker opening for stowage and transport (which will also protect the cone). I'll build it out of 1/4" plywood. It'll take me a couple of days, but I'll post pictures/sound clips/videos when I'm done...

I tried out the new speaker, and it sounds really quite good! Interestingly, I think it sounds more "bass drum-like" if I turn the speaker upside down so that the cone is against my desktop. Probably this is because doing so really mutes out the higher frequencies. Also, my desktop might now also be acting as big extension to the speaker cone, helping those low frequencies come through. I haven't fooled around with capacitor values yet, but it I'll probably try a few before I take it off the breadboard and put it onto perf.

  Now I have to think of how to build the housing. The circuit is quite sensitive to the amount of surface area on the trigger. The sound changes depending upon how much of the trigger pad is touching ground. JM's suggestion of two thinnish pieces of plywood kept a couple of mm apart is a good one, as I could then vary the amount of the trigger that is in contact with the ground pad via "stomping pressure". I've got some aluminium tape (the kind used to repair holes in your air ducts) that I'll line these pieces of plywood with to make the trigger and ground pads. I'll keep the boards separated by a few mm with some double sided foam mounting tape. I'd like to attach the trigger pad to the housing for the speaker and perf board with some sort of hinge so that I can fold the thing up and take it with me. I think I'll have only one control (a pot with a built in SPST switch), and I'll probably mount this to the board (PCB style). I guess the speaker will be facing down onto a thin piece of plywood so that I get that bass boost effect I was talking about. I'm not sure if I'll build a box to cover the back of the speaker (more complicated, but safer), or just let it all hang out (easier, but potentially exposes speaker to damage). I'll sketch some ideas out, and see what I end up with, but any suggestions would be appreciated!

Okay, so I a chance to head to the Goodwill, and I got what I think will be the perfect speaker. It's an 8" 8ohm Kenwood hifi. The magnet is on the smaller side, so it's nice and light (MUCH lighter than my good vintage 8-incher). I think in this case that's a good thing. I don't need a speaker that can take sustained loud playing. I just need a nice speaker that can deliver good low end without any need for a heavy, over-spec'd, super-beefy magnet. I don't have time tonight to try it out all together, so I will report tomorrow on how it sounds...