• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Bruno Putzeys Balanced Preamp - Group Buy

Status
Not open for further replies.
Jump to Latest
#343
Good to see that the GB is now in keep running as it deserve 🙂

I am receiving requests of my 6 inputs boards by PM that I show in the post #67, so I decided with the agreement with Bertel and tfboy to see if there is the interest to start a dedicated GB that will include the 6 input board and in case the front panel board and in case the relevant rotary switch and LEDs.

I repost here the pictures that I send some days ago and this is the link for the GB : http://www.diyaudio.com/forums/grou...ys-preampli-gb-6-input-board.html#post4620322

Thanks and Regards,
Enrico
 

Attachments

  • DSC02673.jpg
    DSC02673.jpg
    706.9 KB · Views: 324
  • DSC02676.jpg
    DSC02676.jpg
    675 KB · Views: 307
  • DSC02671.jpg
    DSC02671.jpg
    796 KB · Views: 304
  • DSC02670.jpg
    DSC02670.jpg
    783.7 KB · Views: 332
#344
Just double checking the latest BOM. Got a couple of components I want to double check. But do we have confirmation of who the manufacturer orders from? No point asking for things that are not their normal supply if there is an equivalent cost and performance part from somewhere else.
 
#345
Bill, below is an extract of the draft email I haven't sent yet, which I think covers your thoughts 🙂

Regarding the high price of the Melf resistors, I've checked and we can change the components to reduce the cost - the only resistors that have to be Melfs are R25 - R28.

All other resistors (apart from 0805 2M2 R10 and R37) can be normal 0.1% 0805 25ppm thin film resistors.

I have updated the BoM to use Susumu resistors. If your assembly team has a preference with another manufacturer (availability / better pricing), I'm fine to switch as long as they are as good or better than 0.1% / 25ppm.
Click to expand...

Is that OK?
 
#346
Personally I would ask them who their preferred suppliers are. The easier we make it for them the more chance of everything going smoothly. But that is just me.

For the record, I'm just cross comparing the MELFs and the non susumi resistors to be sure. Should complete that tonight.

no one has requested the lower gain version, so their loss.
 
#347
Precision Resistors
- should be thin film for best performance including low distortion
- thick film is normally used in the electronics industry for surface mount resistors and is cheaper than thin film and is available in 0.1% but I would advise against using them in this application
- it is why Bruno specifically specified thin film for the resistors in the audio path, other resistors in the his BOM do not have thin film next to the description
- the Susumu resistors currently in the BOM are very good thin film resistors at a reasonable price


regards,

Rick
 
#348
billshurv said:
Personally I would ask them who their preferred suppliers are. The easier we make it for them the more chance of everything going smoothly. But that is just me.

For the record, I'm just cross comparing the MELFs and the non susumi resistors to be sure. Should complete that tonight.

no one has requested the lower gain version, so their loss.
Click to expand...

Lower gain version would be awesome- didn't see that as an option
 
#349
RGN said:
Precision Resistors
- should be thin film for best performance including low distortion
- thick film is normally used in the electronics industry for surface mount resistors and is cheaper than thin film and is available in 0.1% but I would advise against using them in this application
- it is why Bruno specifically specified thin film for the resistors in the audio path, other resistors in the his BOM do not have thin film next to the description
- the Susumu resistors currently in the BOM are very good thin film resistors at a reasonable price

Rick
Click to expand...

Thank you, we have done that to death the last few pages. However the risk remains that as only Mouser seem to stock Susumi and if they are not a normal supplier the price might go up. worth de-risking that!
 
#351
OK all SMD parts look ok assuming in stock and we wont be gouged for using different suppliers.

Only point of contention is the 100pF caps which are 'only' 1%. Personally I think that's more than good enough but Andrew was raising a concern. I can't find an 0805 of higher tolerance on a look around. and don't see its needed. As the 4 caps on a board will be placed from adjacent slots on the tape chances are they will be closer than spec.
 
#358
aradan said:
Is it much more expensive with thin film?

I think Do me tinned to go with thick film and than to replace them on his own with thin film

Sent from my ONE A2003 using Tapatalk
Click to expand...

Yes, that's what I'm saying. Go with what is suggested but I believe Bill is asking if I do this, what do I intent to replace them with later on.

The answer I don't know yet but although through hole can be soldered on smd pads quite easily it is not as elegant, still I might do this (buy a few 1% 50ppm and hand match them). As Bill said, finding an in-stock 2M2 resistor in thin film with the specified specs is quite a challenge. So I will take the thick film SMD component for as long as the BoM indicate the proper parts, everything is golden! 😀

Thanks
Do
 
#359
100pF 1% tolerance capacitors are indeed very likely good enough.
If you assume perfect resistors, then worse case 1% tolerance capacitors will give about 118dB CMRR @ 1kHz, 98dB @ 10kHz and 78 dB @ 100kHz.

If these values are not good enough then you had better start worrying about stray capacitance differences of the PCB traces and the input capacitance differences of the LM4562. 1pF is a very small capacitance!

regards,
Rick
 
#360
2M2 resistor is not in the direct audio signal path, its main purpose is provide a dc bias current path for the LM4562 opamps. Thick film should not be a problem here. Bruno's original BOM does not have this listed as a thin film part.

regards,
Rick
 
Status
Not open for further replies.
Top Bottom