Anyone interested in PCB's for OPA627/BUF634 based headphone amp?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I built a headphone amp based on the circuit of Toni Kemhagen (http://headwize.com/projects/showfile.php?file=kemhagen_prj.htm) that contains switchable crossfeed. I changed the voltage feedback opamps to OPA627 and the current feedback opamp to a BUF634.

I am extremely pleased with the performance of this amp and would like to offer the PCB to others who might be interested in building this circuit. You can find pictures of the bare PCB, as well as a stuffed one, here: http://community.webshots.com/album/186022141gFrRec

The circuit needs about +/- 18VDC to feed the 15 volt regulators. If you want switchable crossfeed you will need a double-pole 6-pos switch.

If there is any interest I'll be glad to produce a BOM with part numbers, sources, and prices. I'm not looking to make a bunch of money on this, only to share the work I've put into laying out the boards.


-Rob
 
Retired diyAudio Moderator
Joined 2002
Maxhawk said:
I built a headphone amp based on the circuit of Toni Kemhagen (http://headwize.com/projects/showfile.php?file=kemhagen_prj.htm) that contains switchable crossfeed. I changed the voltage feedback opamps to OPA627 and the current feedback opamp to a BUF634.

I am extremely pleased with the performance of this amp and would like to offer the PCB to others who might be interested in building this circuit. You can find pictures of the bare PCB, as well as a stuffed one, here: http://community.webshots.com/album/186022141gFrRec

The circuit needs about +/- 18VDC to feed the 15 volt regulators. If you want switchable crossfeed you will need a double-pole 6-pos switch.

If there is any interest I'll be glad to produce a BOM with part numbers, sources, and prices. I'm not looking to make a bunch of money on this, only to share the work I've put into laying out the boards.

-Rob

Looks like an interesting project. I would be interested in a pcb/kit.

--
Brian
 
It looks good but I have a comment about your parts placement. It's better to have all parts on one side of you want to have a good groundplane. The only reason to have it like you have done is if you are going to wave soldering it which I doubt.

I have also a OPA627 + BUF634 headphone amp and if you do it right the result will be good also.

I recommend you also that you add option for SO08 opamps becasue many good ones don't come in DIL08.
 
In small quanitites the PCB price is $12 each + shipping. There seems to be a renewed interest in this so I'll put together the BOM so everyone can see how much it will take to build this. I currently only have one blank PCB left, but if I can get a total of 6 people interested, I can order more boards.

To Peranders: I've had absolutely no issues with noise or ground loops. It's difficult to get all the components on one side when you have a mix of surface mount and leaded components. My original intent was not to try to market this as a kit so flexibility was not considered.
 
I don't think that you had any problems with the groundplane but it maybe "feels" better if you have a more "theoretical" groundplane. OPA627 isn't particulary sensitive but if you have a harsh environment with ESD, RFI, EMI it's always a good rule to work for a "whole" grounplane.

These days it's more like a rule to have a option for SO08 opamps I think. Adapters are the best to be avoided.
 
I like it. The schematic looks pretty versatile, you can build to suit, add or remove parts. The only shortcoming I see is the simple class-A biasing (2.49k, R3,41,52,53), I'd rather use active current sinks, but they could be kludged in. SO8 footprints would be nice too, but if only one choice is available I'd take DIP8 and use SO8 adapters if needed.

How do the versions with BUF634 and CF opamp as output buffer compare?

I'll wait for announcement of purchase arrangements before buying a PCB
 
nuvistor said:
I like it. The schematic looks pretty versatile, you can build to suit, add or remove parts. The only shortcoming I see is the simple class-A biasing (2.49k, R3,41,52,53), I'd rather use active current sinks, but they could be kludged in. SO8 footprints would be nice too, but if only one choice is available I'd take DIP8 and use SO8 adapters if needed.

The biasing resistors were not included on the original circuit I did so I ended up soldering resistors directly to the IC's. I later added the resistors to the schematic and layout incase I were to order more.

How do the versions with BUF634 and CF opamp as output buffer compare?

I never built the circuit using a current feedback opamp so I can't comment on differences. But the layout has the feedback resistors for a CF opamp if you choose to use one.
 
I've got 7 people who are interested in the headphone amp PCB. At these smaller quantities my cost for the boards are $10 each + $10 shipping. So if I order 7 that would be $70+$10 shipping = $80 / 7 = ~$11.50 each.

I have all the surface mount resistors on hand. I can provide all of them (49) for $3.00. They are KOA 1% metal-film (RK73H series).

U.S. shipping is $5.
Int'l shipping is $10.

Let's get a recount based on these numbers. If you would, please send me an email so I can contact each of you directly if need be.

Thanks.
 
PCB for the K's headphone amp

Hi Maxhawk,

I just started to write this email and somehow I must have pressed the wrong key and it has posted itself with just 'Hi'.

Anyway, I would be interested in two PCBs for the headphone amp. The only question is how do I sent money to you? Have you got a PayPal account?

And how much would it be together with the cheapest air mail to Australia?

My direct email addres is:
janusz.pradzynski@dpi.wa.gov.au

I should be grateful if you managed to answer my email before it's too late. The above is my work address (I have no home address yet) and I will be here today until 5PM Perth (Singapore) time zone and of course i'll be at work tomorrow.

Cheers,
Janusz
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.