Hi, I'm planning to build a Frontman 25R, but I can't find TDA1514 anywhere. I've been looking for a replacement for that chip and I've seen that LM3886 is a good replacement, but I'm just an amateur on electronics so I don't know if I have to change the schematic to make this replacement, could somebody help me? thanks!
You'll almost certain to have to make some changes and adjustments, as they don't have the same pinout (or even the same number of physical pins).
This is how I'd approach things . . .
Start out by printing up the respective datasheets (http://www.datasheetcatalog.com/). Take the Frontman schematic (http://support.fender.com/schematics/guitar_amplifiers/Frontman_25R_Schematic_653.pdf) and figure out what the gain is set for, and why the surrounding components are there. Odds are pretty good that the power amp block is similar to the datasheet. Then you can translate that over to an equivalent circuit for the 3886.
That would do most of the legwork for the pros, and they'd have an easier time spotting trouble in a prototype circuit than having to design it from the ground up. I'll help if you get stuck, but I've got to get some rest at the moment so I don't have time to drive into the details right off.
Hope that helps some. :)
Quote from: DJPhil on July 15, 2010, 12:25:07 PM
Hope that helps some. :)
Thanks, it helps a little bit, but I don't have much confidence on my ability on achieving the right changes, 'cause it's my first SS amp. I'll try and I'll let you know!
Hi Jordi.
Agreeing with the earlier suggestion and extending it a little:
I think the full Frontman is a bit too much to start, specially because an important part is unavailable.
Start by making a power amp and its power supply, either an LM3886 or TDA7294.That part of your amp stays forever.
Then you can make a very simple preamp , use it driving what you already have.
Later you can build more and more complex preamps, but going step by step.
Quote from: J M Fahey on July 16, 2010, 12:42:51 AM
I think the full Frontman is a bit too much to start, specially because an important part is unavailable.
Despite being my first SS amp I actually have build a tube amp (a Fender Blues Junior similar amp) and some effects pedals, so I'm not a beginner on building amps, but my electronics knowledge on amps is just a little more than the basics. The problem for me is not building or the complexity of the preamp, the problem is having a part on the schematic that I can't find nowhere, so I think that if with your help we can find the changes needed the rest won't be difficult.
If someone wants to take a look on my tube amp you can see a video on this link:
http://www.youtube.com/watch?v=_rX-Og3EuXs
Quote from: jordileft on July 16, 2010, 03:11:47 AM
Despite being my first SS amp I actually have build a tube amp (a Fender Blues Junior similar amp) and some effects pedals, so I'm not a beginner on building amps, but my electronics knowledge on amps is just a little more than the basics. The problem for me is not building or the complexity of the preamp, the problem is having a part on the schematic that I can't find nowhere, so I think that if with your help we can find the changes needed the rest won't be difficult.
No worries. That's a sweet sounding tube amp!
Looking at the schematic, everything from R55 (which I think is limiting the current draw from the opamp buffer upstream) down is your power stage and should look somewhat familiar. Essentially you'd be replacing C33 (DC blocking cap) down with the LM3886 reference schematic and adjusting the feedback and gain to suit. The TDA datasheet is short and sweet, but the LM3886 has a heap of appnotes explaining the reference circuit and changes you can make to it. You may have to tinker a bit with the finished product to be completely satisfied, but that's half the fun!
I think you'll be surprised how easy it is. These sorts of chips are designed for low external parts count, so they tend to be fairly simple to use. You can also copy off of a schematic for a 3886 powered amp and see what they did. I've got no knowledge of amp models, so I can suggest any, but I'm sure there's folks around who'd probably be able to give you a half dozen examples.
I know that wasn't to specific, but I hope it helps some. :)
Quote from: DJPhil on July 16, 2010, 04:27:01 AM
No worries. That's a sweet sounding tube amp!
Looking at the schematic, everything from R55 (which I think is limiting the current draw from the opamp buffer upstream) down is your power stage and should look somewhat familiar. Essentially you'd be replacing C33 (DC blocking cap) down with the LM3886 reference schematic and adjusting the feedback and gain to suit. The TDA datasheet is short and sweet, but the LM3886 has a heap of appnotes explaining the reference circuit and changes you can make to it. You may have to tinker a bit with the finished product to be completely satisfied, but that's half the fun!
I think you'll be surprised how easy it is. These sorts of chips are designed for low external parts count, so they tend to be fairly simple to use. You can also copy off of a schematic for a 3886 powered amp and see what they did. I've got no knowledge of amp models, so I can suggest any, but I'm sure there's folks around who'd probably be able to give you a half dozen examples.
I know that wasn't to specific, but I hope it helps some. :)
Why should I change C33? this filter cap value has nothing to do with the amplifier used, just with the fc, isn't it? I've been looking the datasheets and schematic but I don't know how to calculate the gain of the TDA1514 on the Frontman schematic. Otherwise, I don't know what would be the difference from the LM3886 datasheet figure 2 feedback which has Rf1, Rf2 and Cf than the feedback on Frontman schematic, with Rf1, Rf2 and a resistor replacing Cf and a capacitor tied to ground between that resistor and Rf2. If I knew the gain on the frontman TDA1514 gain and how the difference on the feedback between LM3886 datasheet and Frontman schematic affects on the formula of gain which appears on LM3886 datasheet, I'm sure that the most difficult part would be solved. Could someone help me with those two things?
I've been thinking and I hope someone could tell me if I'm right, no matter what's the gain on the frontman schematic with TDA1514, as gain is the relation between Vi and Vo given by the components on the feedback, then any components on the feedback on a TDA1514 would be the same gain than in LM3886 if the values are the same, is that right?
Quote from: jordileft on July 16, 2010, 10:40:34 AMWhy should I change C33? this filter cap value has nothing to do with the amplifier used, just with the fc, isn't it?
I said that to be conservative, but yes, it's essentially part of a 50Hz high pass filter. If I were to build a separate board for the power amp section I'd have put everything from C33 down on it, it's just a conceptual delimiter.
Quote from: jordileft on July 16, 2010, 10:40:34 AMI've been looking the datasheets and schematic but I don't know how to calculate the gain of the TDA1514 on the Frontman schematic. Otherwise, I don't know what would be the difference from the LM3886 datasheet figure 2 feedback which has Rf1, Rf2 and Cf than the feedback on Frontman schematic, with Rf1, Rf2 and a resistor replacing Cf and a capacitor tied to ground between that resistor and Rf2. If I knew the gain on the frontman TDA1514 gain and how the difference on the feedback between LM3886 datasheet and Frontman schematic affects on the formula of gain which appears on LM3886 datasheet, I'm sure that the most difficult part would be solved. Could someone help me with those two things?
I can't say I blame you there. The datasheet has a note on the closed loop gain spec on page 7 for calculating gain. The feedback path is a bit convoluted, but the info in the LM3886 sheet regarding the feedback loop applies to the TDA1514. The gain works much like an opamp, with the extra bits rolling off gain at DC and high frequency for stability. The gain calculation for the TDA1514 is roughly equivalent to R3/R2 on the test circuit. Looking at the Frontman schematic and taking R58 in parallel with R59 + R60 I get a gain of about 13, compared to the datasheet circuit of about 30. That sounds . . . close to what makes sense.There may be something going on I don't understand, so I'll pass on certainty and refer it to the pros.
In the end, you can build the preamp section up to around C33, test the output, and configure the LM3886 for whatever gain suits you. There's a guide at the end of the datasheet to help. This is probably what I should have advised in the first place, but I didn't know the Frontman circuit would be such a beast!
Quote from: jordileftI've been thinking and I hope someone could tell me if I'm right, no matter what's the gain on the frontman schematic with TDA1514, as gain is the relation between Vi and Vo given by the components on the feedback then any components on the feedback on a TDA1514 would be the same gain than in LM3886 if the values are the same, is that right?
Sort of, but frequency matters too. There are factors which might cause the specific values of the resistors to change, but the ratio of resistances between Vo and Vi, and Vi and ground will mostly determine closed loop gain. I wouldn't copy/paste the parts values, but it should be close.
Hope that helps. :)
Quote from: DJPhil on July 16, 2010, 01:20:34 PM
Sort of, but frequency matters too. There are factors which might cause the specific values of the resistors to change, but the ratio of resistances between Vo and Vi, and Vi and ground will mostly determine closed loop gain. I wouldn't copy/paste the parts values, but it should be close.
Hope that helps. :)
But resistors value its fixed between the tolerances, isn't it? are capacitive and inductive reactance which changes according the frequency. And being a negative feedback amplifier to calculate gain just needs to equal Vin+ and Vin-, I'm not going to make all the calculations, but it will be calculated in the same way on TDA1514 than on LM3886, I think I'm sure about that. I've attached a drawing of how I would do this schematic section (keeping the previous and later sections).
One more question, what does D10 and D11 on the Frontman schematic do?
Thanks for your help!!
Hi jordileft (Catalan perhaps?)
Nobody challenged your electronics knowledge, far from it, but if you ask, you will get an answer.
What I meant is that SS amps are more complex than tube ones (for a home builder), specially because you have to design a PCB which is a PITA, and easily 10 times more difficult than the actual amp construction.
Tube amps usually have less components, can be built on eyelet or turret board , which is very forgiving, any component can easily be replaced (either Mods or repairs) 1000 times, and most or all wiring is made with ..... actual wires, which to boot can be dressed at will, while a PCB is a "fixed/frozen" design, replacing a component can easily tear the corresponding pad, which is, after all, a thin foil of copper glued to the board.
As of the Mod/substitution.
Basically you need to calculate nothing: both power amp chips are big Op Amps.
Gain, frequency response, etc. are set by the external components, which can be the same.
Differences?
Pinout (1514) - [3886] <-- attention to the bracket type
+in (1) - [10]
-in (9) - [9]
V+ (6) - [1,5]
V- (4) - [4]
Out (5) - [3]
Bootstrap (7) - [n.c.]
Ground (8) - [n.c.]
Mute (3,2) - [8] <-- beware RC nets are connected in a different way, and in a third way on the Frontman; you must use the Datasheet 3886 version.
Recheck what I say, I'm switching back and forth between PDFs and may have made a mistake.
I repeat that you should build and debug first the power amp section, which is different from the original, and only after that tackle whatever preamp you feel confident to do.
When building something new, different , it pays to go step by step.
I myself started 42 years ago with a tube Gibson GA5 straight from Jack Darr's book (PTP on terminal strips), then a Blackface Bassman also on terminal strips, then **the preamp** from an Ampeg BT15 built on Veroboard (the PCB was too much for me) driving a Kit built 100W SS Motorola amplifier. See that the PCB was a big problem for a beginner.
42 years later I have built and sold over 10000 amps (no, it's not a typo, over ten thousand) and currently make my own PCBs, Cabinets, Chassis, Panels , Speakers, Transformers, and even knobs , strip handles, rubber feet and metal corner protectors, but it took *years* and lots of $$$ to be able to make all those things.
Good luck :tu: :tu:
Quote from: J M Fahey on July 18, 2010, 02:29:23 AM
Hi jordileft (Catalan perhaps?)
Nobody challenged your electronics knowledge, far from it, but if you ask, you will get an answer.
What I meant is that SS amps are more complex than tube ones (for a home builder), specially because you have to design a PCB which is a PITA, and easily 10 times more difficult than the actual amp construction.
Yes, Catalan!! you know Catalonia?
Don't worry, I wasn't offended.
Quote from: J M Fahey on July 18, 2010, 02:29:23 AM
beware RC nets are connected in a different way, and in a third way on the Frontman; you must use the Datasheet 3886 version.
What net do you mean?
The PCB thing, would not be a problem, I've already done more complex PCB on other projects. Otherwise I'm thinking about doing it all with soldering paths and bridges. I really enjoy doing that.
Quote from: J M Fahey on July 18, 2010, 02:29:23 AM
I repeat that you should build and debug first the power amp section, which is different from the original, and only after that tackle whatever preamp you feel confident to do.
When building something new, different , it pays to go step by step.
I think I'll build the whole schematic, 'cause there's no critical change, and checking other schematics that use LM3886 the only different thing is the feedback section, which is different 'cause the gain is different.
Thanks for the help!
I have one more question, 'cause this part of the schematic really confuses me. The switch S1-A and S1-B, isn't it doing a loop? what's the function of S1-B? if there was no S1-B the function would be the same, isn't it? In that case I don't understand why it's not a one circuit switch. And why is S1-A 1 and 2 pins connected? Isn't those loops undesirable? can somebody help me?
Just looking at it I'd say that S1B is simply unused. It may be that there's more to the system on a different model that uses the same schematic, and in this version it's just grounded to keep it out of trouble. The loop is barely there in practice, as pins 3, 4, 5, and 6 will be shorted to ground on the circuit board.
I'm pretty sure that Fender just found out they can buy a huge stock of DPDT switches on a cheaper price than buying also ample inventory of SPST and SPDT switches would have cost. The Double Pole Double Throw -switch can be configured to do the same things as all those other switches, but the other switches can't be made DPDT.
On an (sort of) off topic side note, this type of footswitching scheme is one the most cunning circuits I've ever seen in Fender amps, though it's not obvious from a simple amp model as this one with just a single footswitchable feature: the footswitch alters the amplitude of an AC signal, which is then rectifed and used as an input for a comparator circuit acting as a switching logic. The cunning part is, the comparator circuit can provide different switching functions like.
Vin = 0V: feature 1 on
Vin > 2V: feature 2 on
Vin > 4V: feature 3 on
and so on.
Furthemore, because this amplitude information is carried on as AC signal the comparator switching logic can work on interpreting both positive and negative voltages, therefore doubling the amount of switchable features. Furthermore, all this information can be carried in just two wires (AC and GND) to the footswitch. Furthermore, the same AC signal can power on LEDs within the footswitch.
It's absolutely brilliant.
Hi Jordi.
The nets which I refer to are the "Mute/Standby" ones, where on turn-on they apply a certain voltage on certain IC pins, a couple seconds after turn-on.
They typically are made from a resistor to V+ or V- to said pin(s) plus a 10uF or 22uF capacitor to provide the delay.
Since 3 different ones are suggested: Datasheet 1514; Fender 1514 and Datasheet 3886, I simply reminded you that that's one difference with the original amp, please use the one correct for the actual IC used.
Y sí, soy Argentino, y conozco (y amo) Cataluña, especialmente Barcelona pero sin olvidar lo demás.
Sólo la Catedral ya justifica el viaje, o un simple paseo por la Rambla :tu:.
Quote from: teemuk on July 19, 2010, 12:36:09 PM
I'm pretty sure that Fender just found out they can buy a huge stock of DPDT switches on a cheaper price than buying also ample inventory of SPST and SPDT switches would have cost. The Double Pole Double Throw -switch can be configured to do the same things as all those other switches, but the other switches can't be made DPDT.
Thanks! You seem to be a real amp enthusiast! then I'll go with an SPST.
I have two more question, these amps uses a reverb can or digital reverb? anyway, what reverb unit should I buy? I can't get that info from nowhere. And about the transformer, I see that (as being from Europe) I would need a 230V to 20V-0-20V, but how many amperes should it stand? Thanks again!
Quote from: J M Fahey on July 19, 2010, 02:27:57 PM
Y sí, soy Argentino, y conozco (y amo) Cataluña, especialmente Barcelona pero sin olvidar lo demás.
Sólo la Catedral ya justifica el viaje, o un simple paseo por la Rambla :tu:.
Me alegro q conozcas cataluña, yo soy de Mataró una ciudad a unos 30km, un saludo!
QuoteI have two more question, these amps uses a reverb can or digital reverb?
Can. No idea which model though.
Quoteanyway, what reverb unit should I buy?
What reverb units can you find? If you are thinking about to use a same kind of circuit then there are few criteria: First, the reverb tank must have a high enouh input impedance so a plain OpAmp can drive it. A reasonable estimation is that Zin is higher than at least 600 ohms, but likely more suitable Zin will be in the range of few kilo-ohms. The maximum drive voltage swing will also be limited to about +-14V.
You can, for example, go to Accutronics website, find the spec sheet table of their reverb tanks, and then see what models fit the bill. You can find plenty of other helpful info for aimed for reverb circuit developers from that site as well.
Quote from: teemuk on July 20, 2010, 12:06:54 PM
What reverb units can you find? If you are thinking about to use a same kind of circuit then there are few criteria: First, the reverb tank must have a high enouh input impedance so a plain OpAmp can drive it. A reasonable estimation is that Zin is higher than at least 600 ohms, but likely more suitable Zin will be in the range of few kilo-ohms. The maximum drive voltage swing will also be limited to about +-14V.
You can, for example, go to Accutronics website, find the spec sheet table of their reverb tanks, and then see what models fit the bill. You can find plenty of other helpful info for aimed for reverb circuit developers from that site as well.
I've been taking a look at Accutronics website, I have some things clear, but I still have some doubts. That's what I have clear:
Digit 1: I would choose 8, for having smaller dimensions.
Digit 4: 2, for medium decay time
Digit 5: C, for having insulated input and grounded output.
Digit 6: 1, no more options.
Digit 7: B, for horizontal open side down, to put it on the floor of the cab.
But what I don't know is the input impedance and output impedance, I rely on you when you tell me Zin should be 600ohm or bigger, but I would like how to calculate that in order to be able to do it for myself the next time. Could you explain me that?
Any help with the transformer current?
Thanks!
Hi jordy,
Don't loose sleep it's not an exact science.
As long as the drive end is close to 600 Z.
A DMM Reading should be around 50 to 80 Ohms DC will get you in the zone.
If you want to chase the harder stuff you might find some good reading here.
http://roymal.tripod.com/accutron.htm
Down the bottom is all the rev tanks ,,given in both Z and DCR.
The output (pickup side) transducer can be anywhere above 100 Ohms DC and it will work fine with that circuit.
You might want to consider the reality that the rev circuit in that schematic is not the greatest and an outboard unit might simplify construction and reap far better results anyway.
Having spent far to many years frustrated by onboard rev setups I built my own stand alone unit which is all SS and works like magic.
The beauty of an out-board Rev unit is you can take the reverb signature to *Any other Amp* you use.
Phil.
Quote from: phatt on July 22, 2010, 09:49:14 AM
Hi jordy,
Don't loose sleep it's not an exact science.
As long as the drive end is close to 600 Z.
A DMM Reading should be around 50 to 80 Ohms DC will get you in the zone.
If you want to chase the harder stuff you might find some good reading here.
http://roymal.tripod.com/accutron.htm
Down the bottom is all the rev tanks ,,given in both Z and DCR.
The output (pickup side) transducer can be anywhere above 100 Ohms DC and it will work fine with that circuit.
You might want to consider the reality that the rev circuit in that schematic is not the greatest and an outboard unit might simplify construction and reap far better results anyway.
Having spent far to many years frustrated by onboard rev setups I built my own stand alone unit which is all SS and works like magic.
The beauty of an out-board Rev unit is you can take the reverb signature to *Any other Amp* you use.
Phil.
Ok, I'll go with Accutronics 8EB2C1B. The option about outboard reverb seems really good, how do you connect it? do you used is as a pedal in your chain? maybe I'll try on my next project.
Otherwise, could you help me with the transformer current on the secondary? I think it's the only thing I'm still missing.
I've been talking with people from Fender and they have sent me an updated revision for the Frontman, here it is:
Thanks
Quote from: jordileft on July 15, 2010, 10:53:56 AM
Hi, I'm planning to build a Frontman 25R
I going to sound like an amp-snob but ..............................why the time, cost and effort for this amp ?
1.It's not a BAD little amp...
2.It's a FENDER.
3.From a small club stage it can pretty much look (and with a couple of pedals sound) like a 65 Princeton Reissue or Weber/MOJO copy(400-1400 plus the work)
4.And the person wanting to build it is apparently not in the US where they can buy one from Musicians Friend or Sweetwater for $99 with free shipping.
That's my take on it.
Quote from: bry melvin on July 22, 2010, 09:12:33 PM
1.It's not a BAD little amp...
2.It's a FENDER.
3.From a small club stage it can pretty much look (and with a couple of pedals sound) like a 65 Princeton Reissue or Weber/MOJO copy(400-1400 plus the work)
4.And the person wanting to build it is apparently not in the US where they can buy one from Musicians Friend or Sweetwater for $99 with free shipping.
That's my take on it.
Quote from: alotawatts on July 22, 2010, 08:42:42 PM
I going to sound like an amp-snob but ..............................why the time, cost and effort for this amp ?
Despite all that, I've already built a tube amp (similar to fender blues junior) and some effects pedals, so I wanted to try with a SS amp. Here, in Spain, I could actually buy it for about 120€, but I've played old versions of this amp and they sound great with a medium guitar and doesn't have a much complex schematic, and if you plug it, as I plan, with a MIA Fender Telecaster and a Zendrive (built for me) I'm sure it would make you change your mind. As bry melvin said, it's enough loud for small club gigs and, as any amp builder know, the cost, time and effort on building an amp it worths when you hear it for the first time and every time you see or hear it, you can do some mods if you want, use a different speaker, knobs, wood and finishes, so when it's finished you would not know what amp is or it's based from. Even giving it a name. And I really enjoy building an amp. For example, the Blues Junior I built it has some mods on EQ section, adding a presence control, upgrading caps, speaker, adding a standby button,... It cost a little bit more than if I would bought it (also due the thing it was my first amp and there was a lot of things I could do for spending much less money I didn't know) but I'm really proud of it, check the video and tell me if you would know it's a Blues junior: http://www.youtube.com/watch?v=_rX-Og3EuXs
For me, it really worth the cost, time and effort
Hi.
As I see it, jordi is set to build *an amplifier*.
Obviously as a personal project, to learn new skills, to spend a few afternoons doing something he likes, the works.
The fact that it's a Frontman, or anything else, is not that important.
In fact, when somebody who's getting into homebuilding asks me what to do, and wants to start designing from scratch, I usually suggest him to keep it simple , building a straight "Datasheet application" power amp and a simple but good preamp such as Rod Elliot's.
If he wants to go further, I suggest him to copy some relatively simple yet good sounding *commercial* amp.
Hey!!, that Frontman fits the bill !!
Besides, powering that 3886 as the datasheet suggests (+/-28V into 4 ohms or +/- 35V into 8 ohms) will give him a 50 or 60W RMS power amp, which driving a good speaker (Jensen Mod1270) will be a *loud* and quite professional amplifier, well above the original Frontman "25".
Besides, having recently won the FIFA World Cup, the Spaniards are now spirited to conquer the World. :tu: :tu:
Cuídennos la Copa, la tienen en préstamo ,la próxima nos la llevamos nosotros a casa :lmao:
One thing I would do is to build the power amp entirely on a different board than the preamp. If either one proves to be dissapointing in time you can easily throw in something different in there.
Following the datasheet application is (usually) the safest bet, just don't build the bare minimum circuit, which usually omits every stability and reliability ensuring component of which's importance is often discussed further in the datasheets.
BUT, also bear in mind that in case of audio those datasheet circuits are usually HiFi designs with linear frequency response and minimum distortion. Something not neccessarily best for a guitar amp. For example, in case of FM25R, take a look at function of resistor R62 and the additional feedback loop within: This deliberately raises the output impedance of the amp causing the amp's voltage gain (and thus also frequency response) to change in proportion to speaker's different impedance at different frequencies. You will rarely find anything like this from HiFi amps but you'll find that kind of scheme very often from guitar amps because it's a way to mimic characteristics of tube power amps. A datasheet circuit with it's linear frequency response throughout the audio bandwidth will therefore have a very different tone.
In addition, the RC filters in guitar power amps may be configured to deliberately narrow the bandwidth drastically whereas many HiFi-ish designs try to get a linear response from 20 Hz to 20 kHz - something that seldomly benefits a guitar amp. And of course we don't even touch things like soft clipping circuits or tone controlling means incorporated within the power amp: For example, both Peavey Vypyr 30 and Vox AD30VT use a LM3386 chip (and as far as I know, so do some Pritchard amps), yet the external circuitry turns their power amp circuits into something completely different than the generic HiFi application presented in the datasheet of a LM3886.
Quote from: J M Fahey on July 23, 2010, 07:15:48 AM
Hi.
As I see it, jordi is set to build *an amplifier*.
Obviously as a personal project, to learn new skills, to spend a few afternoons doing something he likes, the works.
The fact that it's a Frontman, or anything else, is not that important.
In fact, when somebody who's getting into homebuilding asks me what to do, and wants to start designing from scratch, I usually suggest him to keep it simple , building a straight "Datasheet application" power amp and a simple but good preamp such as Rod Elliot's.
If he wants to go further, I suggest him to copy some relatively simple yet good sounding *commercial* amp.
Hey!!, that Frontman fits the bill !!
Besides, powering that 3886 as the datasheet suggests (+/-28V into 4 ohms or +/- 35V into 8 ohms) will give him a 50 or 60W RMS power amp, which driving a good speaker (Jensen Mod1270) will be a *loud* and quite professional amplifier, well above the original Frontman "25".
Besides, having recently won the FIFA World Cup, the Spaniards are now spirited to conquer the World. :tu: :tu:
Cuídennos la Copa, la tienen en préstamo ,la próxima nos la llevamos nosotros a casa :lmao:
I can't say that better!
When you talk about output power depending on Vcc, do you say that according to graphic 01183349 Output Power vs Supply Voltage? I think I would feed it with the 27Vdc that TDA1514 has. If you were talking about that graphic it would take about 40W, enough for what I need. I was thinking about changing External-Internal speaker connection so, when a speaker is connected to the External output, the internal speaker keeps sounding driving it parallel, if they are both 8ohm there wouldn't be a problem, is it correct? 'Cause I would like to test combining different speakers with the same output.
Two questions, does anyone know the J4 headphone connector's name? I can't find it anywhere? and some help with transformer secondary current?
Quote from: teemuk on July 23, 2010, 07:47:25 AM
One thing I would do is to build the power amp entirely on a different board than the preamp. If either one proves to be dissapointing in time you can easily throw in something different in there.
I appreciate the advice, but I think I will buy it in the same board, I think there will not be any problem with that. In fact, there's no significative changes. The only thing I kept from LM3886 datasheet (which is more hi-fi oriented) is the mute part, which doesn't affect on the sound if it's not open circuit. Otherwise, keeping all in the same board will make much clear for me and simple when mounting on the chassis or cab.
By the way, you better get used to Spain winning the FIFA World Cup. :lmao: