![img_0716[1].jpg](/community/data/attachments/52/52738-9012f82da7b50ad7a1c39104b390297f.jpg?hash=kBL4Lae1Ct)
Jaudio,
Some questions:
1) Which are the circuits you using? I made a search trying to find them on other threads from you with no luck.
2) Where did you get those heatsinks? They look great!
3) What's the reason for that fan? It seems to be placed where it can do little difference for heat dissipation.
Carlos
Some questions:
1) Which are the circuits you using? I made a search trying to find them on other threads from you with no luck.
2) Where did you get those heatsinks? They look great!
3) What's the reason for that fan? It seems to be placed where it can do little difference for heat dissipation.
Carlos
![img_0642[1].jpg](/community/data/attachments/52/52750-c4419b7c9e89f6fe053b9fbad2fef6da.jpg?hash=xEGbfJ6J9v)
1) Inverted with trimmer bewteen + signal input and ground. Check out the thread "lm3886 Bpa"
2)www.bgmicro.com
3)You might be right. If I seal the casing: leave four narrow slits in each corner it should help dissipation.
I will put a small fan in back and just leave two narrow slits in front,that should work.
2)www.bgmicro.com
3)You might be right. If I seal the casing: leave four narrow slits in each corner it should help dissipation.
I will put a small fan in back and just leave two narrow slits in front,that should work.
carlmart said:
Im trying to keep it under $5. So far a spent $3.50 Opa549(4) are samples
I paid
$1 for 4 speaker post
$1 for 4 input caps
$1.20 for 4 200uf caps(bypassing)
$0.30 for resistors and .1uf caps
everything else is salvage
pga2310
This is my first attempt at building a preamp with the pga2310. I really didn’t know what an I wanted so I kinda went for flexibility. The preamp has a buffer in front and a Walt Jung composite (opa-xxx and an AD815) at the output. I have not decided on which dual op amp I will use. I added relays to switch out one or both input and output op amps… I can stack socket for class A biasing. I can change the gain by pulling the resistors out of the pin sockets (the little pins with the resistor sticking out). There will also be a rec out selector.
As soon as a get my three selector I can run full tests
Any suggestions?
This is my first attempt at building a preamp with the pga2310. I really didn’t know what an I wanted so I kinda went for flexibility. The preamp has a buffer in front and a Walt Jung composite (opa-xxx and an AD815) at the output. I have not decided on which dual op amp I will use. I added relays to switch out one or both input and output op amps… I can stack socket for class A biasing. I can change the gain by pulling the resistors out of the pin sockets (the little pins with the resistor sticking out). There will also be a rec out selector.
As soon as a get my three selector I can run full tests
Any suggestions?
Attachments
An update on http://www.diyaudio.com/forums/attachment.php?s=&postid=1183125&stamp=1176550226
With the OPA549s in buffer mode each IC has a dc offset bewteen .0 and .2 mv(in non-inverted mode). This mean I can do away with the trimmers from (+) signal input to ground. It will save me: 3 parts per IC 24 parts per channel.
With the OPA549s in buffer mode each IC has a dc offset bewteen .0 and .2 mv(in non-inverted mode). This mean I can do away with the trimmers from (+) signal input to ground. It will save me: 3 parts per IC 24 parts per channel.
Tested the gain section of the amp using opa445,Im getting 3mv at output. I am really not too thrilled with the offset. Now I have a choice keep going with direct coupling or add a cap before the OPA549s.. BTW I added cap(82uf) between ground and the ground resistor that sets gain.
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