QuoteDidn't mean to break up the "conversational momentum". I'll go somewhere else, I get the message. Embarrassed

sorry tron...

here we go:
the tda1514, i learn, is a good chip, but really difficult to find...
so, before to start a deep conversation about that, is better that you find first one...
about the 50W....
I got the same problem... i want some more watt
But, i think, that if the fender designed this chip in that configuration, for 25W, was because, they knew that this configuration was the better for a good sound...
So, if you wanna "more watt", the first things to talk about is which transformer you have...
if you find this chip, and you got a big transformer you can decide to use two tda1514 for two different speakers.
Like J M said, you can use the same preamp and pilote the two tda1514.
If you wanna more watt, the solution can be the lm3886, that everyone here, for wath i read, have built one.

But the question is:
you wanna build cause you wanna have fun or only for money?
cause, i think, i learn reading and checking for prize of  speakers and transformer, that buy a used frontman is really cheaper that build one....

im sorry, i know....
Of course i know what i had write and your answer back. i check this forum often and with passion !!!
Thanks to you, i built the last project and i was "happy" of the result. lm3886 + esp pages (preamp), (i still have to buy some new plot cause i used the standard (not good enough), plot).
In this case, the will of new build is like a drug for me, i wanna build something different.
Like i said i was thinking about two lm1875 with one speaker each and a different preamp, just for try.
That's all.

Thanks. Marco

i was thinking....just some question...
i didn't find the tda1514.
if i want more watt with my toroidal.... 18-0-18 (120VA).
my toroidal have not power enough for the lm3668
i want use two lm1875 that i have home, each one connected with a single speaker. (but not stereo needed!!!)
but, if is possible i wanna use only one preamp.  I dont wanna make two preamp, i dont wanna double plot and more simple as possible.
How i can do this?
I have to connected simply the two input of lm1875 (with the "normal" chipamp schematic) with the output of the preamp?
and, another question: which one can be a simple pream, maybe only with tone stack and no second channel like distortion needed. Just a clean preamp!!!!
any suggestion?

good, thank for answering me back.

So, im going, this morning,to check if i can find the tda1514 on my electronic shop.

If i do, im going to build this little marshall.

If i dont.....
The main problem in the post before is that:
For this project i dont wanna try and esperiment anything. I just wanna build a complete
amp, already designed and tested.
So my question was if there is a schematic, something about 30W, that you can raccomand me.
Something that you have already listen and you think sound good.
im not interested in a good distorted channel and no in particolar effect.
Something that sound clean and "pure".
I got a good fender acoustic guitar and a original telecaster.
An Amp that can sound good with both would be perfect.

About the two streo channel:
Im not really interested. the idea is play music, a singer and an two guitar player, in small pianobar.
i hope that i cleany explain what im looking for.

thank again....
Marco

hi everyone...
I got a 18-0-18 120VA toroidal transformer that i want use to build a guitar amp.
I saw the circuit of the fender frontman 25R, i think its easy to build, cause the amp stage is with only a TDA1514 and the pre-section seems easy to understand...
i wanna know, if with my toroidal i can build something with more watt, if there's some schematic that you can suggest me instead the frontman?
i'd like something with a IC in amp stage, and maybe easy to build. :-)
I'm able to do good board, i got everything necessary to print board.
Please nothing like lm3886 or lm1875, i've already done. :-)
There's maybe some fender or marshall schematic amp that i can build?
Thank you...
Marco
 

QuoteNice neat work by the way Thumbs Up
Phil.

QuoteI'm impressed as well.  Excellent job!

thank you. i apreciate that.

Now... noise problem.
I change the TL072 with a new one... just to be sure
I connected the central GND star between the to big caps direct to the gnd chassis, where is also connected the Earth from the home power.
The noise now is a little bit less.
But the problem still exist.
If i leave the signal connector free there is a lot of noise, i have to power down 'cause is really annoying and if i connected it to the gnd the noise is less, but still.

In the second jpg that i post you can see al the connection that i have do.
I a few worg i have one power board that supply to different board, one for the amply and one for the pre.
Every board have his own gnd connection.

1: How can i solve the problem noise?
2: is a problem that the plus and the minus voltage are a little bit different? (like +14.50 and -13.80)
3: if i turn all off the master volume the noise really go up.

i wanna try to do another pcb for all the caps with a singol connection, to avoid the problem with all the cablage cause i see that if i get the hand close the system start to noising... is that stupid?

Thank.... Marco

i check all the pcb, and now is working.
Like you said was some kind of flake, 'cause i wash the pcb with some CRC and now is working good.
The voltage now, in the 1-2-3 pin are quite close to GND, and the project is working.
But i have some other problem:
Is so importante that the power is right +15 and -15?
i have -14.55 and +14.37. they have to be equal?
Second thing, everything is a little bit noising... at home i have a NE5532, that's a lot of people sayd that is a good IC for audio. can i put it instead of the TL072, that maybe is a little bit compromise for the bad that append before?

I did pcp design direct 'cause i'm pretty good in that. ( i think )
I have done a lot of pcps, in school and also for work, and i'm pretty sure to have done correctly.
this is not the first pcp that i have done, i have controlled it a lot of times.
The problem is that i worked a lot with digital stuff, like PIC and uProcessor, so my knowledge about analogic signal is not enough to understand where the problem is.
(I really have to start study analog circuit!!!!). (any good volume suggestions?)
I really didn't want to give up, and i'm happy that i find someone, like you, to figure out where is the problem. I say you thank again.

So, first of all, i use, instead of the BC549 another transistor, the BC550, higher voltage and same noise (on the cover is write CC550...)
Second, i left the low input disconnected, ( R2 input not connected, i have to connect it to GND? ).
Here the voltage from every PIN from the IC: ( no signal in input ).
1: -13.17
2: -13.13
3: -12.01
4: -14.62
5:   0
6:   0
7:  0
8:  12.79
The supply is a little bit different cause i add a green power LED with a 600 Ohm resistor in parallel with the 15 Volt positive rail)

It seems that no signal is coming from the tone section, so i guess is a pots problem?
i follow the figure is the esp pages, there's a draw with the pot connections, and is write that the view is from front... i don't know
how can i understand if is only a pots problem?
can i make a bridge from the out of the 1 pin to R9 and check if is working?

the amp is workin good, i tried and is perfect.
I post some photos...

i don't know, the preamp project still not working...
i made everything good (i guess), check and check the things over and over again...
Maybe is a connection pots problem, i do the same that is show in the ESP pages... but still not working. I think that i'm going to let it go.
Have you got some other suggestion for a clean preamp?

wow... amazing!!!
again, i have only to thank you!!!

tomorrow i'm going to do the pcb...
let's see

Thank J M for your advice.

I've already done something like a test board, full of holes, jack and everything i need. i recover the board from a old dvd case player. It is in plastic, so is ok, i think.

Anyway, i check the sch from the project 27 (ESP):
http://sound.westhost.com/project27.htm
like you said, the new one.

here some question, that i have already ask, but i'm a little bit confused, about the capacitor.

I saw this capacitor, from the sch:
C3:   1uF
C8:   1uF
C10: 2,2uF
C15: 2,2uF
C14: 10uF

what i have to use? electrolitics or "normal"?
is i have to use electrolitic capacitor, can you tell me the right positive position, expecially the last three?
I ask you again this thing cause i wanna be sure about what i have to do and don't make any mistake.
thank again...

Marco

yes, i look a lot in the ESP Elliot pages.

I'm wonder is you're talking about the preamp in the project27 or in the project27b.
If is so, whick one of the two do you raccomand? are they quite the same about sound or are they different?

thanks J M for the suggestion of the speaker... great.

I search in the web and I find some good start point... The problem is that most of them don't sell to private, but i think that i'm going to figure out something.
Another things...
I built the LM3886 amp. i have to tell that sound good. I drive an old speaker box of a old marshall ampli that i have.
Which preamp did you raccomand.
I'm don't know, something simple for the beginning, with volume, gain, and maybe controls for the tone. Something clean.
I don't care for the power supply.
Everything have to be ok for driving the lm3886.

Marco

Thanks so much to everyone...
i think that i have understand everything i need for now...

When i'll finish to make the pcbs, i'm going to ask something about the speaker to buy.
I was thinking about two 8Ohm speakers to put in parallel, but i really don't know where i have to start to search...

For now... thank again!!!

No, i think that i explain myself really bad...
Forget everything that i said and we start again.
Sorry i'm italian and is a little bit difficult to explain myself.


So, here we go:

I'm going to use only one transformer, a 150VA, 18-0-18 output. Maybe not enough for the full output power, but anyway good for my needs.

I'm going to use a LM3886, for the amp section, i wanna built it following a sch that i find in this post. here:
http://www.elektronika.lt/_sys/storage/2004/11/30/pic1.gif
I wanna do that in a standalone board, with the input for the power (from the powerboard), input for signal (from the preampboard) and output to the speaker.
Everything until now is easy and clear!!!

The powerboard, have to give the 25/-25 to the amp, and also the 15/-15 to the preamp. 
The image that you post, is perfect. I decide to put also the two fuse there.
You said that the single bridge way is enough, so i'm not going to use the schematic suggest in here http://sound.westhost.com/project04.htm (Figure 1- +/-35V Dual Power Supply).
I saw also, in the ESP page that is used another "little" bridge with a resistor and a capacitor in parallel to prevent loop. (Figure 3 - power supply) from http://sound.westhost.com/project27.htm.
My question is, i have to use it?

And another question, this time for the output jack to the speaker.
I saw that there's a 0,1Ohm 5W resistor in series to the GND center, in my case on the powerboard. I have to use it?

I hope i explain myself a little bit better, anyway, i'm going to draw this thing down, so maybe i can explain my issus better.

Thank again for your patience.

Marco

 

I'm going to use a toroidal that i have home, a 18-0-18, 120VA, i know, maybe not big enough but for now i think that is going to be fine.