SEWA - Seven Watt Amplifier

[dytln_02]

Using
- PC soundcard as input
- Grado RA-1 Clone As Pre-Amps\
- Speaker 60W 8 Ohm
- PSU 5A 30V
I hear little Sound (sory for my bad english)
IRP250N is cold is there something wrong ?
I don't have small speaker ....
how to debug this amps ?

 

[Mad_K]

All the voltage testpoints are in the schematic. What are you measuring?

 

[Mad_K]

Re: Re: DC test: passed ;-)

When should we pay for these Boards ? I guess ill have to build a buffer now to run this OR use the Bosoz Pre-Amp.

Just pay right away; paypal to mads@viiaudio.com 😉

Why do you want a buffer in front of a buffer? BOZ or BOSOZ will be perfect..

 

[Ryssen]

Was the boards 7$ each,how much is shipping to Sweden?

 

[jleaman]

Re: Re: Re: DC test: passed ;-)

Just pay right away; paypal to mads@viiaudio.com 😉

Why do you want a buffer in front of a buffer? BOZ or BOSOZ will be perfect..

I need to know what you need for shipping and the boards. Plus a few parts for me.. can you email me please!

Jase

 

[dytln_02]

@mad_K
Is there is something wrong ?

An externally hosted image should be here but it was not working when we last tested it.

Why IRFP 150N (I use IRFP250N) is cold ???
I hear very little Sound (sory for my bad english) ?
or may be because my speaker i don't have other speaker ?

 

[Mad_K]

Re: Re: Re: Re: DC test: passed ;-)

I need to know what you need for shipping and the boards. Plus a few parts for me.. can you email me please!

Jase

I think it will be 2$ for shipping (regular mail) and 7$ for all the smd components and HMT resistors (for 2 boards). I must warn you though; if you want components from me (at this point) they will all be mixed in a bag, so you'll have to read the numbers/labels..

 

[Ryssen]

I think it will be 2$ for shipping

Does that inklude Sweden to?

 

[Mad_K]

@mad_K
Is there is something wrong ?


Why IRFP 150N (I use IRFP250N) is cold ???
I hear very little Sound (sory for my bad english) ?
or may be because my speaker i don't have other speaker ?

IRFP250N is perfect, no problem there. The =0.72V is because you use 30V rails. Looks to me that you have 2.4A bias. Adjust R5 to 3K3 ro remedy this.
You also need to adjust R1 to 5K6 to get a suitable operating point.

BUT, these are just minor issues. Your problem is Q1: it is not turned on (blown?).

 

[Mad_K]

Does that inklude Sweden to?

Maybe it is a little cheaper? Like 1,5$?

 

[Mad_K]

@mad_K
Is there is something wrong ?


Why IRFP 150N (I use IRFP250N) is cold ???
I hear very little Sound (sory for my bad english) ?
or may be because my speaker i don't have other speaker ?

Looks like you also have an error on your pcb: C6 should be connected to the other side of R6. Then R6 should be connected to Collector of Q3. You now have 25mA through Q3. It should be more like 4mA..

 

[dytln_02]

@mad_K
I have fixed layout but still the same...
now i got
- base q3 to ground = 0.6v
- Diode Zener to ground = 30v
- Source Q1 to Base 30v
I have check Q1, ZD, Q2 all is ok

 

[Mad_K]

lohk, Ryssen: recieved payment request. Seems I need to upgrade to a premier account to recieve credit card payment. I'll look into that. Here are the updated schematic:

 

[Mad_K]

Updated BOM:

 

[Mad_K]

Update: Critical listening test: PASSED ;-)

I'm pleased to report that the Rev.B boards are performing very, very well 😉

I'm up on Living The Music

 

[Mad_K]

@mad_K
I have fixed layout but still the same...
now i got
- base q3 to ground = 0.6v
- Diode Zener to ground = 30v
- Source Q1 to Base 30v
I have check Q1, ZD, Q2 all is ok

Seems that something is VERY wrong with your amp.. What do you have on Q1, Q2 G, S, and D pins (to 0V) ?

 

[jleaman]

Re: Update: Critical listening test: PASSED ;-)

I'm pleased to report that the Rev.B boards are performing very, very well 😉

I'm up on Living The Music

Now im excited to hear these things 🙂

 

[Mad_K]

I'm wondering what is the best way to send these pcbs. Initially I was thinking just to wrap the boards in
some paper and send them by regular mail in a regular envelope. Now I'm worried about customs and
maybe I should use bubble-envelopes. Maybe it is a good idea to use something like this envelope (see attachment).
It is a bubble-envelope with customs declaration and the correct markings. It costs 10USD though...
What do you think? I have no experience with this..

On the content label I can just wite something like "sample boards" and like 2USD value, so you don't have to pay any tax etc..

 

[jleaman]

I'm wondering what is the best way to send these pcbs. Initially I was thinking just to wrap the boards in
some paper and send them by regular mail in a regular envelope. Now I'm worried about customs and
maybe I should use bubble-envelopes. Maybe it is a good idea to use something like this envelope (see attachment).
It is a bubble-envelope with customs declaration and the correct markings. It costs 10USD though...
What do you think? I have no wexperience with this..

On the content label I can just wite something like "sample boards" and like 2USD value, so you don't have to pay any tax etc..

That will work really well. You might want to put paper between the boards. never ship boards faced to face. they scratch and rub away the solder mask. 🙂

 

[Mad_K]

Do you mean that the 10$ padded envelope with customs declaration will work well, or do you think a regular envelope (2$) without declaration will do?