Hi everyone
actually i want to build a versatile guitar amplifier using eminence guvnor 75w speaker.
i want to build around max 30-35 w.
for the power section what chip you suggest?(like 3886 3875 etc ).
can u please refer any good schematic of the power supply?
i have found lots of crying for both 3886 and 3875 in different perspectives.
but you guys please suggest me in terms of guitar amplifier?
do you think 3886 /3875 are more than enough for 30/35w or the TDA chips will do?
what is the difference in producing quality sound for LM3886 types vs TDA 2030 types chips?(in terms of guitar power amp).
or instead i should go with discrete solid state(mk ii)??
please suggest your valuable experience from your DIY journey.
thanks
Basically answered in your other post.
A TDA2050 is just on the edge producing 30W, while an LM3886 will work for ages, because it will be overspecified. (good).
Google chipamps and see what they offer.
fahey thanks for the reply...
plz suggest transformer rating for max 30w +-18v
is dual rail transformer 18v+18v means center tap +18 0 -18?
i am going to add sansamp gt2 clone in the preamp. does it requires to go through any intermediate
circuitry or directly feed into power amp?
another question....
3886 has a 10k pot prior to the onon inv. input. in ggg.com it is mentioned as a 10k trimmer.
should i use it as a pot or trimmer with a fixed value or can eliminate since sansamp circuit has its own
output level control.....
little worried since its my first power amp project.....need you...........
Quote from: paku5535 on February 21, 2012, 03:56:15 PM
fahey thanks for the reply...
plz suggest transformer rating for max 30w +-18v
is dual rail transformer 18v+18v means center tap +18 0 -18?
No, a 18v+18v transformer would be center tapped 18v AC - 0 - 18v AC. There is no +/- yet. You will need to build a power supply that hooks up to the transformer and takes the AC from the transformer and makes + and - DC for your amp. If you need +/-18v for your chip you would need a transformer that puts out 12.6v-0-12.6v (AC x 1.4 = DC voltage after rectification).
joecool please elaborate the transformer rating plz
Quote from: paku5535 on February 22, 2012, 03:54:45 PM
joecool please elaborate the transformer rating plz
I'm not sure how I can spell it out any better than that really. Transformers only output AC, alternating current. You need DC, direct current. So you run the transformer into a PSU (power supply unit) board and that will output your DC "rails" (positive and negative voltages) to run your amp.
Read this thread and see if it helps you: http://www.ssguitar.com/index.php?topic=16.0
Start by reading this to see what you are getting into.
Your amp will be simpler because it will be mono (1/2 of what is shown here) and will have a somewhat simpler Power Supply and transformer than the one shown.
http://diyaudioprojects.com/Chip/LM3886_CA/LM3886_CA.htm
A 18+18V AC transformer will give you about +/- 25V DC, perfect for this amp.
hello fahey and joecool
thanks to both of you for your prompt reply. acually 18v+18v transformer is not available in india....
instead can i use center tap transformer with 18 0 -18 rating..........so through bridge rectifier i can get +-25v (around)...shown in the picture....
what are its drawback.........compared to 18v+18v
kindly reply
Quote from: paku5535 on February 23, 2012, 03:17:28 PM
hello fahey and joecool
thanks to both of you for your prompt reply. acually 18v+18v transformer is not available in india....
instead can i use center tap transformer with 18 0 -18 rating..........so through bridge rectifier i can get +-25v (around)...shown in the picture....
what are its drawback.........compared to 18v+18v
kindly reply
No drawbacks. I have built amps with toroidal dual output transformers as well as CT transformers and they both work just fine. Most commercial amps use CT actually.
thanks for the reply.
please reply me for the following question......
i am going to add sansamp gt2 clone in the preamp. does it requires to go through any intermediate
circuitry or directly feed into power amp?
another question....
3886 has a 10k pot prior to the on inv. input. in ggg.com it is mentioned as a 10k trimmer.
should i use it as a pot or trimmer with a fixed value or can eliminate since sansamp circuit has its own
output level control.....
i will place bit by bit information here as soon as i start the work...
thanks
Quote from: paku5535 on February 24, 2012, 03:14:04 AM
thanks for the reply.
please reply me for the following question......
i am going to add sansamp gt2 clone in the preamp. does it requires to go through any intermediate
circuitry or directly feed into power amp?
another question....
3886 has a 10k pot prior to the on inv. input. in ggg.com it is mentioned as a 10k trimmer.
should i use it as a pot or trimmer with a fixed value or can eliminate since sansamp circuit has its own
output level control.....
i will place bit by bit information here as soon as i start the work...
thanks
Your preamp can go straight into the LM3886 circuit. It's up to you if you want to use a potentiometer in between the preamp and the power amp. You could leave it out, or you could keep it and use it as a "Master" control. I vote to keep it, because it's cool and adds another knob to your amp :tu: It'll work fine either way. Also, you can use a potentiometer or a trimmer. A trimmer is just a small board mounted potentiometer that can't take a knob.
thank you joecool...
how do u print pcb...
i am trying with the copper clad board but the ironing the pcb image on the copper clad is not transferring(keeping the iron at full temparature)........
thank u again for your reply
Watch a few of these.
http://www.youtube.com/results?hl=en&q=iron%20on%20pcb%20transfer&psj=1&gs_sm=1&gs_upl=4493l14685l0l17089l20l20l0l7l7l0l394l3742l2-11.2l13l0&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1024&bih=625&um=1&ie=UTF-8&sa=N&tab=w1
Then practice, there´s no other way.
You will have to clean your board *very* well, degrease it with a good detergent and warm water or *clean* cotton and medicinal alcohol, *never ever* touch it again with your bare hands, etc.
Try different kinds of magazine paper, different settings in your Laser Printer, different pressing iron temperatures, etc.
Once you get the hang of it, they come out well consistently.
hey all
finally i have decided that i will go with lm1875. because i have realized that 20-25 watt is enough for me for my efficient guitar speaker (eminence governor) having spl of102.
now i am bit confused with which schematic to adopt for my guitar amp.(+vcc -vee) type
1. do i require any buffer between the preamp and power amp.
2. for guitar amp what should be the uF value for the filter capacitor.
3. i have decided to run it through 18 0 -18 ct transformer. for moderate efficiency what should be the ampere rating of the transformer.
4. many one are suggesting to use good grounding techniques for minimal noise and hum.. any advise ????
5. what is zobel network? do i have to adopt this for good. where i have to add this in the ckt?
6. what type of delay ckt i can add to minimize on pop sound
(plz see the attachment. this is what i have found by googling) .
7. do i have to attach the earth wire (green ) with the zero voltage pin for safety?
additionally if some one to share his opinion on lm1875 or any thing related to amp building then plz write here..
let me have those answers plz and i will start working on the project. during the time if i have any problem i will post here to get feedback from gurus..
thanks
hey all
finally i have decided that i will go with lm1875. because i have realized that 20-25 watt is enough for me for my efficient guitar speaker (eminence governor) having spl of102.
now i am bit confused with which schematic to adopt for my guitar amp.(+vcc -vee) type
1. do i require any buffer between the preamp and power amp.
2. for guitar amp what should be the uF value for the filter capacitor.
3. i have decided to run it through 18 0 -18 ct transformer. for moderate efficiency what should be the ampere rating of the transformer.
4. many one are suggesting to use good grounding techniques for minimal noise and hum.. any advise ????
5. what is zobel network? do i have to adopt this for good. where i have to add this in the ckt?
6. what type of delay ckt i can add to minimize on pop sound
(plz see the attachment. this is what i have found by googling) .
7. do i have to attach the earth wire (green ) with the zero voltage pin for safety?
additionally if some one to share his opinion on lm1875 or any thing related to amp building then plz write here..
let me have those answers plz and i will start working on the project. during the time if i have any problem i will post here to get feedback from gurus..
thanks to all
1) to 3) google a couple 15 to 30W amp schematics, (Laney/Fender/Crate/Orange/Pavey) and check how they use their chipamps. You won't find LM1875 but a *lot* of TDA2030/2050 which are used the same way.
Same pinout and everything else.
Your PT should be rated 40 to 60VA.
Obviously if you find a bargain 75 to 120VA one cheaper than, say, a regular 50VA one, go for it.
5) the commercial amps will use the zobel network, copy it.
6) don't worry about the pop, no mid or small sized amp cares about it, it breaks nothing anyway.
7) the green wire must be safely bolted to the chassis and must be at least 1 inch longer than the other 2 , so if somebody pulls the power cord heavily the others snap before the ground one.
Unlikely but costs nothing, so ...
Good luck.
EDIT: make the PSU and power amp first, and test it with a speaker and an MP3 or CD player straight to its input.
When you are sure everything is fine, go on with the preamp.
thank Fahey for your input...
Juan forgot two things.
1. Have fun.
2. Post here with your results!
ofcourse!!
Sorry.
I should make that part of my signature ;)
And yes, it's all about having fun here and sharing our experiences with friends. :dbtu:
Cool site.
Or, should I say .... joe-cool ? :lmao: