My first ever Audio related project - Sterio Amp !

I dont agree.
Buying the necessary parts,the time taken for it,building the amp,debugging,getting more parts,tweaking,making a better revision,petrol all take up considerable amount of money(and time).
Unless you know the exact end result which is absolutely perfect,its not going to be cheaper.

This is highly depended on one's skill with electronics. I have always had a 100% success rate with projects I've built. I remember, the shop guys used to dislike me using a multimeter to check transistors before buying them, back in the day.

For a newbie with no background or knowledge of electronics, kits are easy, just solder the input/output sockets, the transformer, screw them all into your cabinet and you're good to go.

IMO (personal of course), I always got a kick out of DIY from scratch with components. It helped that my father was an old school electronics and telecom engineer (from the tube and germanium transistor days).
 
BTW, I'm gonna assemble it tomorrow.
But I don't have any speakers....have to borrow one from my friends for testing.
 
looking for build pics!

Didn't do it :p The soldering iron I bought had a really big tip. I was waiting for my cousin to show up with a smaller one but he didn't and he won't be here tomorrow too.
So, its still there, sitting in the plastic cover it was delivered :eek:
 
This is highly depended on one's skill with electronics. I have always had a 100% success rate with projects I've built. I remember, the shop guys used to dislike me using a multimeter to check transistors before buying them, back in the day.

For a newbie with no background or knowledge of electronics, kits are easy, just solder the input/output sockets, the transformer, screw them all into your cabinet and you're good to go.

IMO (personal of course), I always got a kick out of DIY from scratch with components. It helped that my father was an old school electronics and telecom engineer (from the tube and germanium transistor days).

hi, as for the procurement of components, yeah, its expensive. my comment was on a strict diy basis. I mean the complete joy and thrill is on doing it from scratch. that is entirely diferent from assembling a kit. I feel the kit version is nearly like buying a commercial product. so I like the other way round. but not for the novice. thank you for the comment.

True.nothing can beat designing something from scratch and then getting it to work against all odds.

but,for a newbie(assuming he is learning to handle a soldering iron) can be a bit harrowing.
I have seen people put off of diy,because of the "initiation" to diy.

Like,when i started off,i made a simple 12v dc fan regulator.
I started off with a text book mosfet circuit.learnt(still learning) eagle,routing,then etched my own pcb,drilled it,got the parts necessary,and made atleast 10 models till i got it right.for the money i spent,i could have got two fantastic touchscreen controllers,but i wanted it to be my own idea.

Also,where i live,getting parts is a pain.shopkeepers disregard kids or those who dont bring them big money.and that has made me infamous around the electronics hub for being a real pest.:p

since then,ive progressed to making decent power amps and associated circuits.

then comes my most favourite-the cmoy.i have made atleast a dozen revisions of the design,everytime trying out some new idea.
did they all work?yes!
do they make any audible difference?i dont really know.
I have the pimetav2,3 fiio amps,a millet SS tube amp(not all are mine,but still mine).
i will still keep trying to make newer ones,just to see how much i can over-do it,just for the fun of making it.making it more audio-phool.

It all boils down to what keeps driving you in diy.
 
Ok, I assembled the kit but I ran into some problems !

1. O/p from the transformer (AC) which should be 27-0-27 but is 31.4-0-31.4.
So, the PSU o/p is 41.5 instead of 35 !!! a difference of nearly 7 volts !!
I asked the shopkeeper but he says its the no-load voltage and it would drop down to 27 on load. Bibin is also saying it would decrease a bit but he says be very cautious and check the mosfets if they are overheating.

2. I have wired up the RCA female connectors but...they (L and R) have a common terminal (instead of 4 wires, its only 3)!
Why ?
Is it the GND ?
 
Guys, I'm a bit worried about the high voltage issue (31 instead of 27 V).

What do you think ?
Would the voltage get reduced by 4 volts when the amp is running ?
 
Guys, I'm a bit worried about the high voltage issue (31 instead of 27 V).

What do you think ?
Would the voltage get reduced by 4 volts when the amp is running ?

Generally transformer shows 10% more voltage on no load condition. On loading it will reduce that much. In the end you will get (input X 1.414) - 0.7 = Output. For open load it may be looking more.

You should worry only if you have some caps in the Amp which are <= 35V rating and connected to full rail voltage of PS output.

Dirty trick which I suggest use five 1N4007 diodes (or any 10A diodes) in series of each DC rail with proper polarity which will reduce 3.5V.
 
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Generally transformer shows 10% more voltage on no load condition. On loading it will reduce that much. In the end you will get (input X 1.414) - 0.7 = Output. For open load it may be looking more.

You should worry only if you have some caps in the Amp which are <= 35V rating and connected to full rail voltage of PS output.

Dirty trick which I suggest use five 1N4007 diodes (or any 10A diodes) in series of each DC rail with proper polarity which will reduce 3.5V.

10% less >>> the load voltage would be 37.35 V. So, now, I need to reduce the voltage further by ~2.5V

=>I should use 4 such diodes ?

BTW, I recall bibin3210 saying lower voltage would be better than a higher one. So, I should use 4 nos in series and the other two in parallel, right ?
 
BTW, I broke my Jbl amp's POT while trying to remove it from the PCB :( So, I have to buy a new POT.
I'm gonna buy a logarithmic dual gang POT, hope that I get a quality one.
 
10% less >>> the load voltage would be 37.35 V. So, now, I need to reduce the voltage further by ~2.5V

=>I should use 4 such diodes ?

BTW, I recall bibin3210 saying lower voltage would be better than a higher one. So, I should use 4 nos in series and the other two in parallel, right ?

Before giving his suggestion, bibin3210 must have thought something which I am not aware of.

IMO, each diode drops ~0.7V in forward biased condition- single or any number paralleled, and selected diode must have 10 X of current rating of average current. Paralleling them with multiply its current capability. I thought you will have average current of 1A, so buy any 10A diodes, e.g. 10A01 - 10A07 (if not comfortable with 30A surge current of 1N4001-7).

Keep it simple.
 
What about case?
I'm using an old dvd player case which I don't like.
But...I got it for 150 bucks..so not a big problem.

Would be making a proper case soon.
Before giving his suggestion, bibin3210 must have thought something which I am not aware of.

IMO, each diode drops ~0.7V in forward biased condition- single or any number paralleled, and selected diode must have 10 X of current rating of average current. Paralleling them with multiply its current capability. I thought you will have average current of 1A, so buy any 10A diodes, e.g. 10A01 - 10A07 (if not comfortable with 30A surge current of 1N4001-7).

Keep it simple.
I bought 10 diodes rated for 6 amps of current (its written "6 A 4 MIC" on its body, wonder what does the "MIC" stands for) !
Would it be an overkill ?

BTW, the transformer is rated for 5 amps with 27-0-27 tapping and the amp is 100WPC.
 
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...
I bought 10 diodes rated for 6 amps of current (its written "6 A 4 MIC" on its body, wonder what does the "MIC" stands for) !
Would it be an overkill ?
That should work.
That MIC is manufacturers name in initials - MIC GROUP RECTIFIERS (www.cnmic.com)

BTW what power caps you are using in power supply?

...
BTW, the transformer is rated for 5 amps with 27-0-27 tapping and the amp is 100WPC.
No Problem! It is anyway required.
 
That should work.
That MIC is manufacturers name in initials - MIC GROUP RECTIFIERS (www.cnmic.com)

BTW what power caps you are using in power supply?


No Problem! It is anyway required.

Yeah, figured it out :p

You mean, for filtering ?
Its 2200mF x2 per rail.

Thanks for the reply :thumbsup:
Appreciate it !
 
BTW, I bought two dual gang POTs, 100K and 50K.
It have a click-click kind of a feeling when rotating. Is it a stepped one (it looks just like a normal POT to me) ?

I couldn't get the logarithmic POT Bibin recommended...is there any "trick" to make it behave like a logarithmic one ?
Can I connect them in series ?
 
Fully wired it up and tested it yesterday and of course, today !
Sounds really nice :)
Bass and mids are good but treble is a bit less compared to the others. But I like very harsh "in your face" treble...may be thats why I'm not feeling it.

Thanks to bibin3210 and omishra for their help and all other forum members for their support :thumbsup:
I directly connected my mobile phone to the i/p but in the end, it got a bit warm. Should I stop using it as the source?

BTW, I haven't connected the diodes as recommended by omishra to reduce the voltage. Gonna do that today. Also, would tidy everything up and connect every wire to its proper connectors and stuff by tomorrow. (currently, they are all connected directly)
 
Overall, I'm happy with the SQ of the AMP but very very sad with my pcb soldering and wire routing skills !
 
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