SEWA - Seven Watt Amplifier

[jleaman]

Re: Speakers

You may need high efficient speakers to match this amp...

Are you talking to me ?

 

[Tyimo]

Hi Mad!


I meant this resistor:

"...You can adjust the
gain of the circuit arbitrarily by adjusting the value of R15 without
affecting the quiescent DC values of the circuit. As you decrease the
value of R15 to 0 ohms, the gain will approach 50 (34 dB). As you
increase the value of R15, the gain decreases, with 430 ohms giving 10 dB of gain...."

Now I have 124 Ohm like in the schematic.

I encourage you to try the BZLS

I am in the middle of the listening test with my BOSOZ too.

Greets:

Tyimo

 

[Mad_K]

Sorry, i was thinking BOZ. If you want to improve the BZLS, put in a active CCS. Just lower R15 if you need more gain, otherwise just leave it as is

 

[Mad_K]

Professional SEWA PCBs?

Jason ( jleaman) wants to have professionaly made SEWAr1 PCBs. I have made a pcb layout for prototype production, and I will run this if there is some interest. I've managed to make a nice single sided board, plated through holes, soldermask and silkscreen. Board Size is only 25x80mm. The cost will be 10$ per board. I will only make 8 boards on this proto-run, and then build/test it. Jason wants a pair, so for now there will be only 2 pairs available. If there is continued interest I will have some more boards made.
Post here or email me directly if you are interested.

 

[jleaman]

Re: Professional SEWA PCBs?

Jason ( jleaman) wants to have professionaly made SEWAr1 PCBs. I have made a pcb layout for prototype production, and I will run this if there is some interest. I've managed to make a nice single sided board, plated through holes, soldermask and silkscreen. Board Size is only 25x80mm. The cost will be 10$ per board. I will only make 8 boards on this proto-run, and then build/test it. Jason wants a pair, so for now there will be only 2 pairs available. If there is continued interest I will have some more boards made.
Post here or email me directly if you are interested.

Good job. I can see this project going under toe. SOME ( i say openly ) may want a psb for a Psu. I'll design that if you are ok with that. We can talk more.

Jase

 

[Mad_K]

Update

As it turns out, my PCB supplier will not deliver single sided boards with plated through holes, only double sided. I am in the process of redesigning the layout for a 2-layer board, gold plated, green soldermask on both sides and white silkscreen on top. I want to take advantage of this, and use some SMD parts (0805 and SOT-23). This will be a better performing board, a little smaller 25x53mm, but some are reluctant to do SMD soldering. I can now get the price down to 7USD per board. How do you feel about this?

From this proto-batch there will be 5 pcb pairs available. jleaman and Jack C. have expressed interest, and if they are up to some easy SMD soldering, I have 3 pairs available.

 

[squadra]

I would like to have a pair too, I am very curious about the sound of Single Ended Solid State

 

[Ryssen]

I´ll try a pair.Just tell me how.

 

[Mad_K]

If jleaman and Jack C. still wants a pair each, we can proceed and order the boards

 

[jleaman]

They look really good mad_k SMD my fav.. I'll buy a pair.

 

[squadra]

Would it be possible to order the smd parts too?
It's a bit difficult to buy them in small quantities over here.

 

[rebojorge]

put me down for a pair..... at the bottom of the list

 

[Mad_K]

Would it be possible to order the smd parts too?
It's a bit difficult to buy them in small quantities over here.

I can manage a partial kit with all the SMT parts and the HMT resistors on this batch. Attached is the BOM

 

[Mad_K]

Now they're all spoken for:

2 PCBs each:
-Mad_K
-jleaman
-Jack C.
-squadra
-Ryssen
-rebojorge

Everybody should send me an email confirming this.

Attached is the Rev.B schematic.

 

[Mad_K]

A quick google turned up a few useful pages on SMD soldering:

http://www.fpga4fun.com/SMD.html

http://www.avrfreaks.net/index.php?module=FreaksTools&func=viewItem&item_type=tool&item_id=457

http://www.infidigm.net/articles/solder/

 

[Mad_K]

I can manage a partial kit with all the SMT parts and the HMT resistors on this batch. Attached is the BOM

Cost of these components for a pair of pcbs will be an additional 7USD.

 

[Mad_K]

Jack C. had to pull out, so there is 1 pair of PCBs available

 

[lohk]

please put me in for a pair

thanks
Klaus

 

[Mad_K]

Now they're all spoken for:

2 PCBs each:
-Mad_K
-jleaman
-lohk
-squadra
-Ryssen
-rebojorge

Everybody should send me an email confirming this.

lohk, Ryssen and reborge; could you please send me and email?

 

[Tyimo]

BOSOZ FUSE problem

Hi Mad!
Sorry for the off topic question, but maybe you could help me.
After 3 years operating my BOSOZ's fuse (F-1A) blowed 3 times in a couple of days.
The amp always worked very well. I checked everything in the amp and all the reference voltages are O.K. In the test I operated with F-2A fuse.
What do you think, is it normal or paranormal?? What could be wrong?
BTW, is it O.K. ,if I use the + and the ground output for the unbalanced operation with the SEWA V1?

Greets:

Tyimo