UPDATE the problems were solved and soon I will update with schematics and finished build pics,I hope this thread helps someone else.
UPDATE here is the latest schematic working great so far.
http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519B_schematic.jpg
NEW SCHEMATIC COMING MUCH BETTER
CAB COMING SOON!
Here are some sound clips they sound like they were compressed for the server,if anyone wants the original MP3s PM me
http://vibecat.com/brymus
Hi all,I need some help I recently got some tda1519b chips and decided to make a guitar amp with one.
I followed the schematic in the application notes for the BTL at 12watts and simply replaced the LM386 in my Ruby type amp with the tda1519b using the right pins and a small heat sink.
I am using a 12V supply with a switch between pins 7 and 8.
The pre amp is a TubeScreamer topology using a NE5532 and a few FETS it sounds great going into the lm386 but the tda1519b not so much.
Also this thing is getting HOT I mean REALLY HOT!
I have a 8 ohm load and after a minute or so I am shutting it off cause of the excessive heat.I am using a fairly good size heat sink but maybe not enough.
I am powering the amp with 8 AA nihm cells putting out just under 12V
And for testing I am using two 16ohm 5watt spkrs in parallel from an old TV.
After almost 5hrs of googling this http://munkey.hopto.org/projectsdir/audiodir/simpleamp.php and 2 TV schematics are the only schematics I can find.
I have it like this but its not right can someone show me what I am doing wrong?
I have been trying all day to make this work without any luck.
Is my input V or my input Z wrong? If it works great with the 386 chip?
Hi there:
I had been looking around at the link that you posted, and checked the TDA1519B datasheet too. If you look the datasheet and compare it with the circuit of the link, you will note that the switch is between the 7 and 8 pins, and the wire goes from 7 to the C1 and C2 caps, NOT from the 8 to caps. Maybe it is your issue. Note that in the site of your link posted above says that " This is the schematic for mono... (don't go by this schematic here, its wrong. Click on it and use the bigger one)" If you go with the bigger at the linked one its the same that the datasheet.
Here the link of the datasheet http://www.datasheetcatalog.org/datasheet/philips/TDA1519B_CNV_2.pdf (http://www.datasheetcatalog.org/datasheet/philips/TDA1519B_CNV_2.pdf)
Check page 8.
Let us know how its goes.
Regards.
Hi Brymus.
Excuse me but I just don´t like any of those "TV optimized" chips.
I see them as simplified to hell, where saving a 1 cent resistor means U$S 10.000 (20 years salary in China) in 1000000 TV sets made monthly. Their no parts count makes them attractive to beginners, but ultimately frustrating, because they lack important things like any sensible gain adjustment, and more important: stabilizing stuff such as Zobel networks and the like.
That´s why your humble LM386 is better.
I´d suggest using an old LM383/TDA2003 , or, if you go power crazy, a tried and true TDA2005 which, by the way, provides quite higher power and efficiency with your 12V supply.
PS: their using just *one* 1000uF to decouple *two* amplifiers/speakers almost made me sick. Disgusting!!
What´s next?: making undersized PCB holes so the component pins fit with some pressure, to avoid soldering ???? Give me a break!!
Hi thanks for the replys.
I have the caps on the wire to pin 7 I have it wired exactly like the data sheet.
The only difference between mine and Munkeys' diagram is I have only one signal + going to pins 1 and 9 and have pins 5 and 2 going to ground.
His "corrected" schematic shows the + signal going to both pins 1 and 9 and pins 2 and 5 as well,surely this is a mistake right?
The amp has to be grounded somewhere doesnt it?
As far as using a different chip ,I already bought these and would like to make this work.
If you look at the picture of Munkeys amp you will see the EXACT same heat sink I am using.
He stated that he added that after the fact,My chip would have already melted had I not had it.
I think it takes less than a minute for it to heat up so much its almost to hot to touch.
(the sink not the chip)
I have checked pin 3 and have exactly half V+ there so I assume thats correct in BTL it shows it not connected to anything.
As it is I get sound but the HEAT makes me shut it down.
Shouldnt this chip shut down by itself if it were to overheat?
Isnt that what they mean by thermal shutdown and overload protection?
I really appreciate any help with this as I am well :loco after trying all day and night yesterday to no avail.
OK I triple checked everything Googled for hours,and even found a German forum where they were having the same problem(but I dont read German)so I dont know how they fixed it.
Only the guys amp was heating up super fast (like mine)and the solution involved pins 2 and 5 and the ground being tied to the power? Isnt that just a short?
I was able to translate one page and He smoked several chips ordered 4 more still having the same problem,
He stated it was either bad chips or data sheet error?
Then(on the next page which I couldnt get to translate)he solved the problem very simply,
And said it roared to life and embellished the thread with beer drinking smily's
So I used a much larger heat sink with fins ,now it takes about two minutes to heat up :loco
I have sound and at one volume its actually pretty good.About halfway its decent tone.
I am using a 50K pot instead of the 100k I had before.
With the volume turned down it makes a horrible hum sorta noise and with the volume up its a terrible screech.
Does this info help? I can tell this amp will be quite loud if I ever getting running right.
On the TV schematics I found they have a 6800pf going from the input to ground what does this do?
Also one schematic had both sides of the RL tied to ground with .1 caps again why?
And shouldnt the spkr have caps on both the +and- terminals since its floating?
Sorry if these seem like silly questions but I am trying to understand this chip and circuit,and really want to get this working.
From what you are saying it sounds to me that the chip is oscillating. You may have the input and output leads or circuitry too close together especially if you are using matrix board. The 6800pf going to ground on the TV amps may have been put there to stop this.
By the way Pins 2 & 5 are ground. Ignore the + in the symbols munkey used he has probably just cut and pasted the same ones.
Tony
OK thanks for that I believe it is oscillating "wildly"
Update I have tried so much its about 50% there,
I increased the heat sink even more- used one off a pentium3 That helped alot,let me realize the spkr had to be decoupled.
The data sheet is wrong I used a 220uf on each side of the spkr this got it going,NO HEAT :tu:
But still oscillating at low and high vloume and not much sound,sounds awful still :trouble.
Tried the 6800pf from input to ground this helped the oscillation at low volume. 8)
Messed around with adding Bourchers cells changing the cap values going to the spkr.
Changing the value of the 6800pf cap,no improvement.
Added a 56K resistor from input to ground fried the first chip,WHY?
Finally just used one cap on the spkr- big volume increase so different values I try.
Anything smaller than 22uf it oscillates at low or no volume.
Anything larger and I start loosing volume but still oscillating at higher volume.
At this point with the 6800pf cap and the 22uf on one side of the spkr it sounds like a decent 3-5 watts it actually gets a nice distortion by uping the gain on my clean channel.
The dirty channel oscillates at all but the lowest gain needed to get the signal through the two clipping diodes in the feedback loop of the 5532 chip.
So where its normally louder its now the quieter of the two and its easier just to use the clean channel with a pedal.
So if I can just get rid of the oscillation at higher volumes this amp will be ready to put in an enclosure.
ANY SUGGESTIONS PLEASE?
I tried running it off an 18V 1.5amp power supply with no improvement over the 8 AA nihm cells.
Should signal ground be separated from power ground with a cap or resistor?
Do I need some kind of RC network between the SPKR leads?
>>"ANY SUGGESTIONS PLEASE?"<<
Yes ! Emphatically !! = Trash that piece of sh*t/junk (your choice)
If even the factory suggestion is bad, what else can be said?
Go for a real power chip: TDA2002/3/4/5/6/30/40/50 and follow factory instructions.
If even the nerdy techno-obssesive Germans have trouble with them !!! what else ?? and no , it´s not a racist/despective comment , quite the contrary.
Even if you get them to work and even sound beautifully, but only if submerged in liquid nitrogen, well, that´s not good engineering practice.
Quote from: J M Fahey on August 12, 2009, 05:04:43 PM
>>"ANY SUGGESTIONS PLEASE?"<<
Yes ! Emphatically !! = Trash that piece of sh*t/junk (your choice)
If even the factory suggestion is bad, what else can be said?
Go for a real power chip: TDA2002/3/4/5/6/30/40/50 and follow factory instructions.
If even the nerdy techno-obssesive Germans have trouble with them !!! what else ?? and no , it´s not a racist/despective comment , quite the contrary.
Even if you get them to work and even sound beautifully, but only if submerged in liquid nitrogen, well, that´s not good engineering practice.
In all seriousness, a TDA might be a good way to go. I'd look into it.
Without seeing the schematic of the exact circuit you used and some photos of wiring and board layout it's kind of difficult to guess what's wrong.
You have AC coupled the volume control potentiometer from the chip's inputs, right?
The BTL circuit doesn't need AC coupling for the speakers since the DC potential at both speaker terminals should be equal and hence there is no DC current flow from one terminal to another. If AC coupling makes this circuit work better it is a clear indication that you have a DC offset issue that is disrupting the proper operation of the chip/circuit.
---
I am hundred percent sure that the chip will work well in the circuit depicted in the datasheet, assuming board layout is done correctly.
EDIT:Crap I feel so stupid right now :duh
I think Teemuk is right and I think I found the problem as I was getting ready to take pics for
him.
I will let you know as soon as I find the camera,I think the others with the same problems proly did the same thing...The simplest oversight ever...
Thanks again for the input and sticking with me through this guys.
And Teemuk while I hold your opinoin in the HIGHEST regard same as RG and the like.
I am 90% certain that this chip will NOT work with the application circuit from the data sheet.
Please, no disrespect intended I very much appreciate your time helping me with this.
After days googling I found a company called Conrad offers kits with these chips and forums from europe are full of people having the same issues as me.
One guy reported his IC exploded after a days use and was propelled through his enclosure on to the floor where it burnt a hole in his rug his heat sink was twice the size of my Pentium3 sink and was pure copper-not to say he had it wired right he went off the data sheet.BUT STILL EXPLODED?
Its kinda hard to mess up a layout that only involves 3caps-I have succesfully built TrainWreck -Marshall clones which is much more difficult and layout sensitive than this chip amp.
BUT I am not an engineer just a monkey who can read schematics...And copy others.
YES I have a DC offset issue,BUT why IDK
I will post a schematic of my preamp so you can explain what I am doing wrong.
I fried a second chip sort of,I overloaded the input with my guitar and a single FET now the DC offset makes the chip unusable I have one more left.
Apparently this chip needs a very low input my guitar is enough to drive it.
My best luck so far was with a single 22uf cap on one side of the spkr and a 56n from input to ground this only had two issues,
The Volume was like a tone control (first order filter) so that 90% volume offered the best tone.
The other issue was it still oscillated at low-no volume.
I fixed this by moving the volume pot behind the buffer after my tone control.
This produced a lower output but no oscillation and no tone change with the use of the volume pot.
It was actually pretty decent at this point just not a 10-12 watt output,so I continued.
Every stage of my pre-amp is decoupled with 100-330n caps.And I used a .47uf input cap to the PA.
I also tried my Multi FX staight in through a 1m volume and a FET buffer it has both line-and low level output,even the low level output was overloading it at 3/4 volume.
I am going to go with another chip but would like to learn why I had so much difficulty with DC offset and oscillation.
I also learned its better to have a chip that uses external components for feedback and gain control ,decoupling and the like.
YEP I FOUND IT :tu:
OK Teemuk you were absolutely right it works perfect from the data sheet circuit.
What you said got me looking for where the circuit wasnt decoupled...
Before I explain let me start by saying I mostly have built tube amps and not solid state and the test area I have set up with my breadboards has been used for lots of pedals,and a few 386 based designs.
That being said see if you can spot the problem from these pics- its as clear as the nose on my face.
I sorta feel like an idiot but then again I understand how this happened.
PICS
(1) http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519Bbuild034.jpg
(2) http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519Bbuild032.jpg
(3) http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519Bbuild028.jpg
(4) http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519Bbuild002.jpg
(5) http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519Bbuild008.jpg
(6) http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519Bbuild010.jpg
Finally here was the OH so simple solution its the reason I couldnt bridge my 386 chips either,
I thought it was because I was using the high output versions and no heat sink on the DIP8 chips.
Gosh the simplest thing can make a big difference
http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519Bbuild021.jpg
The whole folder so far is here I will update it with schematics and pics of the finished cabinet when its finished
http://s419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/
Really thanks for the effort guys at least its fixed with my 3rd and last chip.
This is my second chip amp build(I have built several 386 amps though)
Hey Teemuk do you think the signal ground should be tied to power ground?
Thats the way I have it now with the signal ground on one bus and the power ground on another and tied together at the pins of the IC.
Also now that its fixed do you think my 386 amp would be OK as the pre instead of taking it from the 386s preamp?
I will post a schematic for this in case anyone else using this chip wants to copy my build.
It sounds fantastic REALLY I am impressed- I got these chips at Apex Jr for .79 cents each.
I am glad I didnt give up it was worth the effort.
I just wish it had more components the and ability to adjust the circuit,like feedback and gain.
Now I have the confidence to start my lm3886 build and found what would have been a problem for that circuit as well before ruining one of those chips or worse. :o
HINT the answer and the reason the ICs werent working right is in the fourth picture down ::)
Let me guess, the two jacks below are speaker jacks and their sleeves short to chassis/ground?
QuoteHey Teemuk do you think the signal ground should be tied to power ground?
Thats the way I have it now with the signal ground on one bus and the power ground on another and tied together at the pins of the IC.
Yes, they need to be tied together (after all, both pins need a ground reference) – but preferably at one point only. I would try tying them together at the main ground point in the power supply (likely the grounded pin of the main filter cap), but if the pins of the IC work just as well then it's fine. It's all about finding the best layout anyway and sometimes it happens by experimenting a little.
The thing is mostly a noise issue; preventing power supply ground return currents from inflicting the signal ground return currents. They all return to main ground point so joining the two separate ground returns together at that point might be the least-noisiest configuration (think star grounding principle).
QuoteAlso now that its fixed do you think my 386 amp would be OK as the pre instead of taking it from the 386s preamp?
By adding the LM386 there you'll be increasing the overdrive originated in the preamp. The Ruby's preamp is just a clean buffer that prevents the low input impedance of the IC from loading down the guitar. Its gain is less than unity. If you already have a tubescreamer –type circuit preceding it, it introduces all the buffering you'll need and the FET buffer can be ditched.
You can try adding the LM386 there and see if you like the result. The LM386 will likely need some attenuation at its output to prevent overdriving the following TDA1519.
Thats awesome you got it working! Thanks for all the updates, very good info!
Quote from: teemuk on August 14, 2009, 05:17:05 AM
Let me guess, the two jacks below are speaker jacks and their sleeves short to chassis/ground?
Pretty much -You nailed it- one jack is the input the other is usually output when I build pedals or a spkr jack if its an amp.
I had forgot that they were uninsulated jacks (switchcraft)-therefore the input ground was connected to the output :duh
It didn't matter when the spkr needed to be grounded (single suply SE )or building a pedal.
But the load wasnt "floating" when BTL
I wish you guys knew how much hair pulling a cussing(3days worth) that little oversight caused me.
I am thankful I found it BEFORE frying my last chip.I was about to give up.
Again thanks for the info Teemuk I havent pinned my new schematic yet but am looking forward to your opinoin of the pre-amp I made on my own.(I actually calculated the knee points of the filters for it)
Gosh ! :o Zap ! :( Boom ! :duh You mean all the time one of the chip "hot" output pins was grounded ??? :loco
Inkooreedibul !!!!!!
Well, thanks God you noticed it on your own, good for you. :tu:
Anyway I still find that if *all* those other guys *do* have plenty of problems with this chip, they can´t all be grounding one of its outputs, especially if built from a kit, there must be some stability problem there.
At least I´ve never seen anybody complaining about the TDA2005, a classical and very popular BTL chip.
I don´t find it strange that it´s very popular with guitar amp builders, it´s used in the Fender AmpCan, Peavey Solo, Nobels Streetman, my own "Callejero", very probably in some of Crate's Hogs, etc.
Congratulations on your workbench, it´s much tidier than mine (no kidding)
Got curious about those beautiful lizard-skinned pedals, ¿what are they?
I´ll dig one of my TDA2005 powered Callejeros and post some pictures.
Hey, I found a few pictures of the small one (2 channel, 1x8", LeSon Tweeter,20W RMS, 12,6V 7AH gel battery, built-in charger)
(http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action-view¤t=Call2001.jpg)
(http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action-view¤t=Call2002.JPG)
(http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action-view¤t=Call2003.JPG)
(http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action-view¤t=Call2004.JPG)
(http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action-view¤t=Call2005.JPG)
They come in up to 100W RMS, 2x12"+Tweeters but even the 20W TDA2005 version is enough for many public places, including Subway stations, Bank halls and Mc Donalds type restaurants.
Well, those pictures didn´t show up.
I'll try again:
http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action=view¤t=Call2001.jpg
http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action=view¤t=Call2002.jpg
http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action=view¤t=Call2003.jpg
http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action=view¤t=Call2004.jpg
http://s755.photobucket.com/albums/xx198/JMFahey/Callejeros/?action=view¤t=Call2005.jpg
Hope it works
HEY JM :duh I KNOW I MEAN CRAP :lmao:
Yeah it was that simple...
DUDE I love that little Calle amp thats SO SWEET looking!!
DO you mind sharing the schemtic and power supply set up?
It sounds like you have already pioneered what I am trying to do- AWSOME rechargable
with built in charger- I am months and months away from that.
But that has been my goal with moving into chip amps away from pricey tube builds.
I do plan on getting some other TDA chips the 2003,5,6,9 -2030- 2050 -7265(50watter)
When I can afford another Mouser order
Oh thanks on the pedals ,those are a few TS type clones,A RF drive from SEwatt.com, an ROG Omega ,a FF design based on the ROG Sili faceII,a 5 band EQ(not finished),
And a version of Gus Smally's "Rocket"
in the bin are a half dozen completed and tested FF builds waiting for enclosures.
If you look in this pic you will see the amp I built them for its- a remade version of my own using the EVJ platform,Hammond ESE OT, 10 watt EL84 ,Marshall/Fender tone with a Ghia tonestack.
http://i419.photobucket.com/albums/pp276/Bry928/EVJ%20Mods/augtooctober077.jpg
Ok, no problem, PM with your EMail and I´ll send you the board and component side .
As an advance, here´s the actual populated board, both sides.
I only solder the TDA2005 pins *after* it´s actually bolted to the back panel, to minimize stress at the board pads.
I was able to do some more testing.
My battery packs just dont have enough current for full volume.
I tried the supply (12VDC 3.2A)I was gonna use but its a switchmode based supply,LOTS of noise,
even with HUGE filter caps :'(
SO I will have to use something else the amount of volume was very suprising with 3amps available.
I mean it was louder and than I expected definetly close to 12 watts.
Using the 386 as a pre also gave more volume but I must not of had it coupled right as there was noise at certain levels.
Maybe a buffer between the output of the 386 and the tda input?
Also I tried a 4ohm load (3.7) for about 30 minutes and the difference was I didnt like the extra THD 10% 15watts-4ohm vs 1% THD 12watts- 8ohm
and the Really big heat sink actually got fairly warm so 6ohm(tested) is lowest for good sound and smaller heat sink from this chip.
I need to draw out the schematic at this point so I can get expert advice from you guys how to improve further.
All in All I am very pleased so far,I cant wait to try some of the other TDA chips.
Here is the schematic of how it sits now-
http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519B_schematic.jpg
It has a fair amount of clipping going on it emulates an old tube amp fairly well IMO
It has a smooth overdrive going on,in the clean channel the louder you get.
The OD channel sounds good from a little diode clipping mixed in,(low gain)
to all out clipping from all the components.
The idea was to get some light clipping from the FETs as well,I think that is happening IDK for sure.
And to compensate for the loss of the tonestack,which helps tame the signal out of the op amp.
If I could change it it would be to get the clean channel -cleaner, maybe not possible with the 386 and this chip amp?
It evolved from this 2 channel Ruby build here http://i419.photobucket.com/albums/pp276/Bry928/Pedals%20and%20effects/SSamps/3862channelamp-small.jpg
I apologize for the hand drawn schematics the first one should be pretty legible though.
Any suggestions? Thoughts? Ways to improve?
Any critisisms welcome.
Also I plan to use two transformers so the pre and power amp have different supplies.
I will draw that out later.
Hi Brymus, very good design.
I bet the sound is good too.
Good components/blocks combination.
The only thing that´s unnecessary is the buffer built around Q2; the signal coming from the previous unity-gain Op Amp is actually lower impedance as-is rather than going through Q2.
Congratulations.
Post some MP3s.
Thanks JM
I will try it with out that buffer(Q2) and see about getting some sound clips.
I also want to try some other line in source (FX, another pre-amp)directly to the PA.
So I can better tell how much clipping is coming from the PA vs the preamp.
Alot of the clean channel overdrive(if not all) is coming from the 386 chip clipping.
A regular NJM386B would probably be better suited as well.
I also left the gain pots the abilty to overdrive the opamp if desired.
I got the master volume idea from you in another thread :tu:
I'd love to hear a sound clip, please post one if you can!
OK the usual disclaimer -spinal injuries few years back(for real)carpel tunnel,bad arthritis
and I cant play. :tu: :lmao: EDIT Oh yeah and the clips sound worse off that server if anyone wants the original MP3s PM me
But the clips will give you a fair idea of the tone and what I mean by tube emulating.
http://vibecat.com/brymus
Recording technique- one channel is pencil condensor at spkr off axis,other channel is large diaphram condensor 3-4 feet out.
Cab 2X12 1XJensen Elec Lightning and 1XCrate Custom
Guitar Jackson Warrior Elite-Duncan humbuckers hot bridge(OD clips) jazz neck (clean channel clips)
Into Tascam US144-Mixcraft(cheap program)
NO EFFECTS OR COMPRESION the reverb is the room itself these tracks arent even EQ'd
All tracks tone control set in middle the master is at less than 30% except the first track Where both master and volume at 50%
Track1 Clean Channel-gain on 386 at minimum Fink Ployd
Track2 Clean Channel-gain on 386 at 30% Long cool Dress
Track3 Clean Channel-gain on 386 at 80-90%(max) SRV WannaBe
Tracks 1-3 channel gain at 30%
Track4 OD Channel-gain on 386 at minimum Tenacious B
Track5 OD Channel-gain on 386 at 40-50% MegaBrymus-1519Magix
Track6 OD Channel-gain on 386 at 80-90%(max) I'm not Jimi
Tracks 4-6 channel gain at max and volume at 80% master 30%
I revised the schematic. I will post it tommorow .It sounds right now.It could be adjusted for an even cleaner sound by lowering the value of one cap,I like it the way it is now.
I will post the revised schematic as well as suggested mods (clipping,EQ)and it should have the standby switch to prevent spkr pop(not bad really).
Anyone know a better MP3 hosting site?
Hey Brymus: impressed by the sound(s) you get, but even more by your recording technique.
I never saw a better example of "keep it simple" giving such good results.
So let's see if I got it right: the main distorter is the LM386 itself, being helped by the first "distortion pedal" type preamp, and power-boosted by the TDA1519, going into a 2x12" box, picked by 2 condenser mics, a very close up one, the other at around one meter, everything happening into a quite live room.
Is that so?.
If that's indeed the case, wow!, the little humble LM386 is going places it *never-ever* thought would visit.
What we hear is the final result , of course.
If at all possible, post a picture of the recording session, so we can see the type of box, the speaker and microphone placement, etc.
O course please post your project in the "project contest" too, even if still on breadboard.
You are absolutly correct JM,
I should also note I was using 12 AA Nimh for PA and a 9V for pre amp.
and thank you for the kind words.
I got a chance to listen to the clips and they sound great! On the first clip where it is all clean, is that going through the LM386 still?
I'm glad someone is doing this project btw, for about 2 years I've been thinking about doing a LM386 as a preamp and never got past plugging my little gem into my dean markley or lm3886 power amp (worked really awesome actually).
Thanks Joe I am glad you like it :tu:
Here is a much better revised version of the pre amp. http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/386PreAmp_2.jpg
The key to a full yet clean tone lies in the cap on the bass boost switch,
Alternately a two way switch could be used for 3 different settings adding to the 120n
Which sets the knee pretty high around 700-800 hz (with 100n) if I remember right.
Using two 120n caps works well to clean up the flabby bottom end,only requiring a little
more on the volume knob to get the same "breakup" from the 386.
While a 220-330n requires backing off the guitars volume and/or easing up on pick attack to keep from getting flabby sounding.
I also recommend adding the standby switch as in the TDA1519B data sheet.
Also a 2 pole 6 position switch could be added to the OD channels feedback loop for 6 different diode clipping combinations- add some hard clipping diodes to the output on a switch and you have 14 different diode clipping sounds as well as the infinite EQ and gain options.
Another thing is the tone control a full Treble Middle Bass tone stack would allow even more tonal control.
I am very pleased so far- now to finish the power supply and figure out how to make a charging circuit.
Oh yeah Joe its going through the 386 in all of those clips.
I need to re-record the clean clips to show the difference lowering the 330n in the op-amps feedback loop makes.
I like 120n+167n added in on the clean channel (287n total)
At this point I would say breadboard this for yourself and try it,
I think I have nailed "tube breakup" really well.
I also need to recalculate the filters to provide some real numbers.
But it does sound really good now.
Quote from: Brymus on August 26, 2009, 10:00:21 PM
Oh yeah Joe its going through the 386 in all of those clips.
I need to re-record the clean clips to show the difference lowering the 330n in the op-amps feedback loop makes.
I like 120n+167n added in on the clean channel (287n total)
At this point I would say breadboard this for yourself and try it,
I think I have nailed "tube breakup" really well.
I also need to recalculate the filters to provide some real numbers.
But it does sound really good now.
Thats great work you've done there. So it goes into an opamp for the tone stack, then into the lm386 preamp circuit, then on to the 1519 poweramp - right?
The LM386 has enough gain that I'm considering doing a passive tone stack in front of it.
Hey I thought I would give you an update on this.
I tried numerous tonestacks both before and after the 386.
SO this is after many trials.I am very happy and have played it alot it makes a great clean boost EQ,and can get clipping in a variaty of ways.
I have been using it like a pedal in front of my other amps and even my wife commented on how good it sounded(she likes heavy music)It sounds insane overdriving my Valve Jr or 18 watt with it.
It is much more versatile than before and so many shades of rock and metal are available.
The only downside now is the knob count I have run out of room for more,as I used a 25k for the 2 diodes to ground and added a 100K in series to the 1m on the OD channel so that its easy to set the 100K for classic rock then dial up the 1M pot for heavy sounds,And also I have a 47uf on pin 7 of 386 that isnt shown.
Here is the latest schematic - pre-amp only- note low power 386 this time and other subtle changes.http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/PreAmpAsPedal.jpg
Also I asked a member at DIYstompboxes to draw a PCB layout, it isnt verified yet but it is here http://www.diystompboxes.com/smfforum/index.php?topic=79693.0
Thanx to Sean K for that layout.
I have been using 9V battery and with the master volume it works fantastic, swapping in the lower power 386 helped too.
I really would like to expand it to two actual channels each with its own TMB tonestack.
But then I'm thinking a bipolar V supply would be better too along with mosfet switching so
I will make that another preamp altogether and call this one good.
Except I do plan on adding a rotary switch with a couple of different diode options including a mosfet diode clipper.
I hope someone finds this useful I have spent months working on it finding what sounds best to me.And am very pleased with it.
Any sound clips of the little beast available? I love the grind of a LM386 overdrive, it sounds great!