• 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.

First One - mosFET amplifier module

Hi all,

I am loving my First One V1.3 very much. But since yesterday I have some noise over the speakers when there is nothing playing.
I had some doubt over my signal wiring so I swapped it for the here mention UTP wire. This helps a bit.
So I went to my preamp(s) and cables, no matter what I do as soon as I connect a preamp (my DCB1 or DAC/pre) I get this noise.
My question is do I have two noisy preamps (did not had this problem before with those) or is there something wrong with the input on the FO which comes to light when I connect something to it.

I hope that the silence by LC is because he is on holiday.

R.
 
Hi all,

I am loving my First One V1.3 very much. But since yesterday I have some noise over the speakers when there is nothing playing.
I had some doubt over my signal wiring so I swapped it for the here mention UTP wire. This helps a bit.
So I went to my preamp(s) and cables, no matter what I do as soon as I connect a preamp (my DCB1 or DAC/pre) I get this noise.
My question is do I have two noisy preamps (did not had this problem before with those) or is there something wrong with the input on the FO which comes to light when I connect something to it.

I hope that the silence by LC is because he is on holiday.

R.
Did this noise just appear, or has it been there all along you just didn't notice it without a source signal. What type of 'noise' is it. Hum, crackle, etc?
If it is a ground loop hum, I've found with my amps (not the First One), that sometimes it (the hum), can be masked, or not obvious if you are using a portable source device that is not connected to the mains. When you then connect it to a source using mains the ground loop is completed and the hum is more prominent than before. This usually indicates a grounding issue within your amp. Not sure I'd be ready to blame the First One amp itself yet, but LC may have some thoughts.
 
Good news! From a friend I lent a Pre- and Power amplifier which don't have unwanted noises.
So after connecting, reconnecting etc. the outcome was 1 (of two) noisy amplifier, 1 (of nine) noisy interconnects and 1 (of one..unfortunately) noisy First One Amplifier.

So dumped the interconnect, going to repair the noisy preamp and dismantled the FO to change some things (after advice from some of you...thanks!).

So after hours everything is playing very, very nice! and I am very, very happy (let the weekend begin early I say).

Thanks for your input and effort.

Now I can start with the finishing touches.

R.
 
Listening test and comparison before release

Hi guys :wave2:

It has been awhile, holidays are over and new First One v1.4 finished.

Now listening tests will be performed between black and silver amps, since silver is a bit modified with different parts in CCS.

Outcome will bring the one with better SQ which will go into production. SQ tests are needed to ensure you'll all get what you've paid.

Silver amp below.

Regards, L.C. :cheers:
 

Attachments

  • IMG_0514.jpg
    IMG_0514.jpg
    435.5 KB · Views: 785
  • IMG_0507.jpg
    IMG_0507.jpg
    464.9 KB · Views: 678
  • IMG_0505.jpg
    IMG_0505.jpg
    437 KB · Views: 650
  • IMG_0512.jpg
    IMG_0512.jpg
    461.5 KB · Views: 631
  • IMG_0508.jpg
    IMG_0508.jpg
    534.5 KB · Views: 641
  • IMG_0506.jpg
    IMG_0506.jpg
    366.8 KB · Views: 332
  • IMG_0516.jpg
    IMG_0516.jpg
    462.9 KB · Views: 249
  • IMG_0515.jpg
    IMG_0515.jpg
    364.2 KB · Views: 222
Well, most of us haven't payed yet: we are waiting for order confirmation ;)

We wish you good ears and enjoyment.

Cheers,
M.

Hi and thanks for good wishes Max :)

I don't want to accept money from anyone before modules are ready to ship. ;)

Order confirmations will follow as soon as we'll finish listening tests and final design considerations implemented, I want them to be flawless. :)

Regards, L.C. :wave:
 
Hi Fetman
Nice to have you here.
VSSA is basic CFA amp design based on ancient single ended amp topology only in a symmetrical manner. Legacy of that single ended, single supply amps are caps in FB path, which is also the case in VSSA.
First One v1.4 is completely DC coupled with no caps in signal/feedback path. It is rather complex CFA topology design, with no spares on semis and with SQ in mind as main objective. That is why I took myself more time to make listening tests as should, making modifications too if necessary.
We were pushed to vendor's part of the forum so no schematics from me in the future.
Regards, L.C.