Pedal based practice amp TDA 1519b

[Brymus]

OK I am glad you are so serious about building your own bass amp.
To be honest if you want something decent for rehearsals with the band look into a pair of LM3886 chips,or google "gain-clone amps" or chip amps.
Try SS guitar.com and DIY audio.com for some examples.
These low wattage chips which are great for guitar amps arent going to cut it for a bass amp that sounds good.
For a small practice amp you can use the TDA2050 with a dual supply pre-amp as well(+15V/-15V)or the like,this would sound much better.
The ESP pre-amp looks good I havent built one but others claim its a good pre-amp.
Or google your favorite SS bass amps and see what chips they use and how the pre-amps are built in them.
Look at the Peavy Basic 50 This has a great sounding pre-amp made from 4558 opamps (I own a modded one)
Get a nice toriodal tranny like the 84VCT 200VA one at Apex Jr for 22$ and you will have plenty of power.
Or even the trannies at Radio Shack can work.
Since the LM3886 is often used as a subwoofer I am certain it will make a good bass amp with the right pre-amp feeding it.
I hope this info helps you.
Its alot of work doing all the googling/research and reading but worth it in the end.

[Brymus]

Here Bubz read this thread I would try that FET2B pre-amp it sounds nice in the clip,again the LM3886 is mentioned.
http://www.diystompboxes.com/smfforum/index.php?topic=79204.0

[Bubesz]

I think you misunderstood it I mean, ok, if it doesn't sound good with bass, I'll use it with guitar, because it's a guitar amp (and I'm a guitar player, but I want to buy a bass, too). And I was at our local electronic shop, but they don't have TDA1519B, only TDA1521. Can I use that one instead of 1519?

The another question is about the power supply: Do I have to use a 9V and a 16V supply separately for the preamp/power amp, or can I make my own supply? For example I would use an adapter, and make a supply with a  9V output and a voltage doubler circuit with 18V output for the power amp. I don't think that plus 2 volts would damage the chip.

And if I buy a bass, perhaps I'll build a bass amp, too.

[Brymus]

OK Bubz I did misunderstand you.
NO you cant use the 1521 instead of the 1519 in my schematic,in a pin for pin basis.
The pinouts are different.
Also the 1521 chip is designed for mains fed apps.It wants a +16/-16 supply.While it can use a single supply it would need to be 32V to get the full output of that chip.
The 1519 is designed for car audio it wants a +12V/0V supply.
I chose this chip for its cost and the 12V supply (I tested with AA rechargeables)
The reason I chose 9V for the pre-amp(actually it can run on as much as 18V)
Is so it doesnt exceed the max voltage swing on the input of the TDA1519 - I have since been using a 6V supply but 6-9V is OK.
The 386 chip can drive a spkr on its own so I was keeping the output down with a lower supply voltage.
I also noticed the 1519 data sheet lists a BTL application(as used in my amp) with an example the 1521 doesnt,not to say you cant BTL that chip but they dont show you how in the data sheet.
Hope that answers your questions better.

[Bubesz]

Thanks for the help. Fortunately in another shop they said that they will order me TDA1519b and some 2n5457-s, and they have everything else I need. So next Thursday I'll make the shopping part of the build

BTW, does this chip needs external cooling?

[Brymus]

OK cool I hope you like it.
Yes the chip needs a heat sink.Look at the pics at SSguitar.com- the link is in the begining of this thread.
When using a 4ohm load that BIG (from Pentium3) heatsink actually warmed up a little bit,
using a 6 ohm load or higher it doesnt get warm at all.
So I think something half that size would be OK if you use 8ohm load or higher. But why have to worry?
I tried a 16ohm 2x12 cab and it sounded great.
Also I have since lowered the resistors on the first FET(input buffer) to 1M (instead of 4M7) and 2k2 .
I also raised that small cap in the feedback loop to 500p.These changes reduce noise in the pre-amp.
The sound clips were recorded BEFORE those changes.It sounds even better now.
For easy you can use 9V battery for pre-amp and run the 1519b off a transformer 12-16V .

[Bubesz]

Ok, I'll buy a heatsink then. I think I'll use a voltage doubler, for example this: http://www.coolcircuit.com/circuit/voltage/ BTW, if I use this circuit with a 1000mA adapter, it would split it. Will the amp work with 500mA current?
And do you have a PCB or a layout for the amp, or do I have to make my own?

[Brymus]

OK ,I would try to salvage a heat sink or make one.But if you must buy one then do the chip needs it.
And as for your question about the 500ma being enough,well
My intial intent was to run the whole set up at 18V but this was to much with the 386 chip in the circuit as it overloaded the input of the tda1519 TOO much.
Worked good when leaving the 386 out...
Anyway also if you read ,I recomend the lower output 386 which runs on 4-12V instead of the higher output one which runs on 5-18V.

Sorry but to answer your question you will need at least 1amp to get decent sound from the 1519,maybe 500ma works but is not very loud.
You can always try and see.
But a 12V 3.5 amp supply would be the best for full output and volume - from the data sheet.
Google calculating VA and watts and keep in mind 18V is highest recomended operating voltage.
Then figure what 12V 3.5 amps is in VA then figure the same VA at 18V and see how many amps you need for the same amount of VA.
It will be less than 3.5 thats for sure  but alot more than 500ma.
With the right load,heat sink and a 18V supply you can actually get 15watts in the usable bandwidth but since the guitar is a narrower range I would guess the actual wattage available would be higher than that even.
As for a PCB I use perf for all my builds and Sorry I didnt draw a layout.I just breadboarded it first then use that layout for the perf.
If you want you can treat the pre amp as a seperate circuit build it then build your chip amp and connect them.
Whatever works on the breadboard should work as your layout.
Also READ THE DATA SHEETS for all the ICs you will be using you will find lots of helpful info there.Sometimes they even have transfers
for PCB designs.

[Bubesz]

Well, if I calculated it right, it's about 2,3 amps. And it's more than my 9V adapter can originally give, even without splitting. So the homework for me is to find out how to power this thing without buying a new adapter

[Bubesz]

I finally had some time to design the PCB and to buy most of the parts, so here is my layout: http://kepfeltoltes.hu/091011/1224680777K_p_070_www.kepfeltoltes.hu_.jpg
This is only the preamp, I'll make the power amp section later.
Sorry for the bad quality pic, I hope you can figure things out. The blue wires are jumpers. Look out for the pads of Switch 1 and 2, the pad of Sw1 is very close to Sw 2(bass boost), but it should be wired with the other pads of Sw1. On my layout, the bass boost cap is 220n. And perhaps I'll add a trace for 9V, and use jumpers to connect them to power pins.

Does this look good to you? Tell me if you find any problems. If it's OK, I'll etch it tomorrow.

My second question: I have an LM386N-1 instead of NJM386 BD. Is it good enough?

[Brymus]

I couldnt open your pic to look.
And I'm not that great at layouts,I breadboard then use perf.So maybe if someone else can look and tell you.
The LM386-1 should be better than the LM386BD as its a lower wattage version of the two.
Use a socket for your ICs and Qs and even the tone caps then you can easily mod or swap out parts.
I have since changed the tonestack and it sounds much "Heavier" now. I have been using the pre-amp as a pedal and I really like it.
Here is the latest version of my pre-amp. http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/PreAmpAsPedal.jpg

[Ben N]

Loos and sounds great. I'll bet those 6" C-V woofers Apex has would make for a great dedicated cabinet, too.

[Bubesz]

I couldnt open your pic to look.
And I'm not that great at layouts,I breadboard then use perf.So maybe if someone else can look and tell you.
The LM386-1 should be better than the LM386BD as its a lower wattage version of the two.
Use a socket for your ICs and Qs and even the tone caps then you can easily mod or swap out parts.
I have since changed the tonestack and it sounds much "Heavier" now. I have been using the pre-amp as a pedal and I really like it.
Here is the latest version of my pre-amp. http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/PreAmpAsPedal.jpg

http://img86.imageshack.us/i/kp070.jpg/, if it's working.
Hm, does the new version sound much better? If I can find the new parts at home, I'll use them intstead of the old ones. Fortunately, there's not much difference in the shematics, mostly the values are changed. Does the new pair of diodes do a distortion boost?
I think I'll etch my PCB, and make pads for future mods, for example a changed tonestack, more diodes etc.

[Brymus]

Hey Bubz I would really like someone else to reply about your layout -
Like I said I'm not great at them,To me and I could be wrong ,I think having the feedback loop so close to your output signal (on its way to the 386) might cause some interference.Again Im not sure and would advise you to get someone elses opinoin too.
The way I did mine (on perf) is to go from left to right (on the schematic)(right to left on the perf) keeping the ground and V+,Vref seperate and keeping the signal ground seperate from supply ground on the TDA IC . I tied the grounds together by the largest filter cap.
This makes the layout long and skinny,But the pots follow along nicely that way.
If I get time I will install a program and draw what I did.

Yeah Ben that CV 6" is one of the better spkrs I tried ,almost as good as a 6"Jensen MOD but not as good.Still for the price you cant go wrong.

[Brymus]

Sorry I forgot about the pre-amp.
Yeah it sounds better now,you can scoop the mids or boost em if you want,and you can roll off the high and low end seperatly.
The diode combo sounds much better too.
Using a 220n on the switch is good you will like that it depends on your taste and playing style really,make it sound good to you then report back what you liked 
I dont really use the Bass boost switch anymore.It sounds BIG with the TMB stack and the 2 diodes to ground clip the low end alot.
So I added a 25K pot in series to them instead of a switch now I can clip out the low end as much or little as I want while adding some more texture to the signal.
The rest of the changes were because when I tried the pre amp as a pedal I discovered it to be VERY noisy alot of high end noise,the
TDA was filtering out with its narrow bandwidth.
So I made it friendly to use as a pedal and now it sounds better than ever.
You can up the small cap in the feed back loop of the first IC to 1000p or add a small like .0003uf cap to ground at the input of the 386
Or whatever kind of low pass filter you want to knock the high end down.
I tried both and went with 1000p in the feed back loop.
You can add a preamp out jack and that adds some versatility to it.
As well as PA in that way you can you line level effects to drive the chip amp.
My multi FX proccesor sounds really nice straight in to the TDA1519

[Bubesz]

Ok, I made some changes to the layout, made it wider, so there's more space between signal route and the feedback loop (if I'm right, it's the part with the diodes. I don't know if it's a problem that the signal trace is close to the ground trace.

[Bubesz]

Another questions: I am using a Pentium 1 heatsink... Do I only have to attach a heatsink to only one side of the IC, or both sides?
The grounding of the power amp goes to signal ground or supply ground? And do I have to connect them somewhere?
And can I use a PC power supply (230W) to power the amp, or is it a bad idea?
The voltages and currents:
+5V:23A
+12V:9A
-5V:0.5A
-12V:0.5A

[Brymus]

OK I added the schematics and sound clips to the gallery.
Please look here for them along with the PCB transfer Sean K made for it>http://www.aronnelson.com/gallery/main.php/v/Brymus/TDA1519b_386AMP/

Feel free to use for any personal/non commercial use.
It will work with only the 386 as the amp too,or as a pedal driving another amp,or as a preamp to a bigger amp(all using it without the TDA1519b)
I have tested it as a pedal and tested it as a pre amp with a few different amps,so its verified for those uses.
The only thing not verified is the PCB tranfer Sean K made if someone uses it please report back ,thanks
Bryan

[modsquad]

   Wow that is really cool.  I would love to play around with this.   Could you post the the actual PNP.  I only saw the parts layout in the gallery.   Again great work.

[Brymus]

Thats all I have at the moment,Sean has sent me the artwork its still in the mail at the moment.
Feel free to use that to make your own,the schematics are there too.
Bryan