completed chipamp pre

[maf_au]

Thank you for posting th BOM. Is there a specific capacitor type/manufacturer that you recommend for the other caps (the non-polarized caps)? I am just potting together the parts order now for this board.

This amplifier project of mine keeps getting more expensive every day...

Amen to that

Dcibel, what brand and type have you found for the low/ultra low ESR EL caps. I have to admit to not having much luck at all finding these sizes locally. I'm beginning to think that Australia is a quality cap desert Does Digikey/Mouser sell them?, I may have to do an import order if I can't find them locally.

Michael

 

[Russ White]

Amen to that

Dcibel, what brand and type have you found for the low/ultra low ESR EL caps. I have to admit to not having much luck at all finding these sizes locally. I'm beginning to think that Australia is a quality cap desert Does Digikey/Mouser sell them?, I may have to do an import order if I can't find them locally.

Michael

Michael I will send you some 47uf ultra low ESR. Enough to complete the project. Cheers!

 

[maf_au]

Michael I will send you some 47uf ultra low ESR. Enough to complete the project. Cheers!

Russ, you are too kind. Now I definitely owe you a beer!

Are they the only critical ESR caps I need to worry about in this circuit?

Michael

 

[Russ White]

Russ, you are too kind. Now I definitely owe you a beer!

Are they the only critical ESR caps I need to worry about in this circuit?

Michael

Well... on the power supply low ESR would be prefferable but anything will do.

The other caps are all film types, so no issue there.

I am reworking the power supply a little, so hold off on you parts for that. I should have it done in the next day or two. Busy weekend for me.

 

[DcibeL]

I was just going to ask why there is different sized capacitors on each side of the power supply, but I will await your modified PSU.

Just for reference on the Low ESR caps, Mouser has the closest thing with the Xicon caps. However it takes a very long time for shipping from mouser for me, plus the addition of customs fees, so I will be using Panasonic "low impedance" capacitors from Digi-key. They have a slightly higher series resistance rating than the Xicons, but I think they will do okay.

 

[Russ White]

I was just going to ask why there is different sized capacitors on each side of the power supply, but I will await your modified PSU.

Just for reference on the Low ESR caps, Mouser has the closest thing with the Xicon caps. However it takes a very long time for shipping from mouser for me, plus the addition of customs fees, so I will be using Panasonic "low impedance" capacitors from Digi-key. They have a slightly higher series resistance rating than the Xicons, but I think they will do okay.

They will be fine, the only thing to stay away from are the low grade "standard" electrolytics and the low leakage, as they tned to have really high ESR.

Those Xicons should be just fine.

Check ebay. I got some great low ESR 47ufs there for a song.

 

[DcibeL]

Yes, ebay does have some Nichicon loew ESR 47uF caps, but not in small quantities from what I can see. I don't need 200 of them . I did however manage to pick up a pair of OPA627AP chips for a measly $10USD. Saved me a few dollars over the $50 cost from Digi-key. There are several lots of these IC's still available on ebay if anyone is interested.

Just a heads up.

 

[Russ White]

Sometimes you just want to hang your head in shame.

Ok, there is a serious error in the yardbird design. It will always operate in unity gain. Whoever can tell me why wins a (virtual) cookie.

I will be fixing it before I send them out, its a simple change. I can't believe I did that.

The Freebird does not have the problem.

Cheers!
Russ

 

[VT67]

Russ

It seems that nobody here can detect the error, I for one sure can't. Can you tell us what it is, the suspens is killing me! It's my birthday today so don't let me think to hard

Cheers

 

[Russ White]

LOL, sorry GeWa, well the gain setting resistor (feeback to ground) R6 is on the wrong side(circuit wise) of the feedback resistor.

 

[tobias_svensk]

Doh, was just typing that

 

[Russ White]

Doh, was just typing that

LOL typos and everything?

Geez I should really look before I submit, I type way to fast.

 

[Russ White]

Here is the fixed YardBird.

The funny thing is since I used it in unity gain I didn't notice!!! Until... i wanted to increase the gain and wondered why when I changed the resistor twice it did nothing!!! DOOOOOHHHHHH.

Well its fixed now.

 

[Russ White]

Final tweak before etching

Ok, about to etch...

 

[VT67]

YES, YES, YES, etch please

 

[Russ White]

Updated PS

Here it is....

 

[DcibeL]

Thank you for the power supply update, but may I ask what the value for C6 is?

 

[Russ White]

Maybe this will help.

 

[tobias_svensk]

Nice going Russ

I don't know if I have missed something here but why a 100nF filmcap on one outrail and a elko on the other?

 

[Russ White]

The data sheet only calls for .1 uf (film) for the 78xx, but for 2.2uf tant or 10+uf elco for 79xx. I chose the latter. 47uf matches the vaules on the PREs and its a good fit.