First One - mosFET amplifier module

[pinnocchio]

See AMB's project called α24 ("alpha 24") for balanced to unbalanced or vice-versa

The α24 fully-differential line amplifier

You can set the modules at unity gain and voilà!

Ciao!
Do

 

[Eric06]

In case, here are some others solutions for balanced to unbalanced interface.
- from jims_audio
- from diyre

 

[Darkheart]

Thanks for information! PCBs from DIYRE looks most attractive.

 

[danny_66]

LC has almost the FO 1.4 ready.

But here's my fresh FO 1.2, I just finished it last week.

Time to upgrade to version 1.3 😀, so it gets a better chance in a shootout against Juma's Cubie2 class A amplifier.

LC can you send me the 1.3 upgrade info?

Regards,
Danny

 

[Xerxes75]

Hi danny

I love your ref-speakers. You were sitting a long time on these FO modules but you're still faster then me... I am almost there..

Which power supply are you using? ( I am not starting over the PS discussion but I am just curious.

R.

 

[danny_66]

Thanks, I like them too 🙂
Those are the AudioPower DPS500/S, they work fine.
But there's now also the new AudioPower DPS500/UR that has my preference.

 

[Lazy Cat]

LC, are these output transistors matched for M and L version?

For First One M mosfets are matched by Semelab, for First One L matched by us in +/-2,5 % Id range.

 

[Lazy Cat]

LC has almost the FO 1.4 ready.

But here's my fresh FO 1.2, I just finished it last week.

Time to upgrade to version 1.3 😀, so it gets a better chance in a shootout against Juma's Cubie2 class A amplifier.

LC can you send me the 1.3 upgrade info?

Regards,
Danny

Nice built, superb speakers.

Do shootout with First One M v1.4

 

[danny_66]

Thanks !
Yes, 1.4 is on my list but first 1.3 🙂

 

[Xerxes75]

Diodes grounding

I think have asked somebody this question earlier but the answer got lost....

The grounding scheme shows MUR160 diodes, these are pretty hard to get... it seems. (of course I can find them but I don't want to order just a few diodes).

Will other diodes do the trick?

R.

 

[Lazy Cat]

Will other diodes do the trick?

Yes, as long as they maintain 1 A they'll be fine, ie. 1N4004 or similar. Low Z connection from each First One module's GND ensured by capacitors on the module, galvanic connection from GND to chassis provided by DRD circuit. In any case metal chassis must be earthed from mains inlet connector's earth (mid) pin.

 

[Xerxes75]

Ok!

 

[svhegges]

My loved F5T said goodbye tonight.
When is the V 1.4 ready? I'm signing up for 2 modules as soon as possible. Thanks a lot. Best regards Sveinung.

 

[ben123]

I just landed on a picture of the backside of a FO1.2 module;
https://hifiduino.files.wordpress.com/2014/10/dsc04821.jpg

This is so nicely build !

There is more info about the 1.2 modules on this site;
https://hifiduino.wordpress.com/category/amplification/

 

[Myint67]

Hi
I have to sell lazycat factory chassis build with fisher sk157 and first one two module (one need to re measure basic and offset ) I change new set of Semilab .
Furutech IEc, two DC offset .
Selling price $280 (fix) plus shipping .

I understand I put wrong place buy here is best for lazycat fan !

 

[Lazy Cat]

For the set with a chassis that's a damn good price.

 

[Lazy Cat]

My loved F5T said goodbye tonight.
When is the V 1.4 ready? I'm signing up for 2 modules as soon as possible. Thanks a lot. Best regards Sveinung.

Blue smoke left the F5T, or it was just retired?

At the moment testing of a preproduction serial modules is taking place. Components values has to be tested again on at least four modules to be sure all are optimal, before turning the green light on.

Hopefully in June first deliveries will take place .

Regards L.C.

 

[jbruziti]

Thanks, I'll do my best.


Well S, M and L will have the same front-end engine, so quite determined SQ, the main differences will be in the output stages and number of output power devices present. 😉

So, it's clear that for example FO v1.2 has and most probably will have a pair of a complementary Alfet transistors in a version 1.4M. I assume that FO v1.4L will have two pairs of these Alfets. Will FO v1.4S have one half of one pair of these Alfets? 😎 Or will have a FO v1.4S a different transistors, or the same transistors, but just will have a different circuit or offsets?

 

[Lazy Cat]

First One variants

First One S - dual NP output mosfet, 120 Wrms/4 Ohm, 50 x 70 mm

First One M - one pair double die output mosfets, 230 Wrms/4 Ohm, 50 x 100 mm

First One L - two pairs double die output mosfets, 450 Wrms/4 Ohm, 50 x 160 mm

Assuming these power responses covering the most of DIY-ers needs on smallest footprint possible.

Especially suitable for HQ active power monitors or multichannel HT systems.

DC coupled enhanced CFA topology, one step beyond.

 

[smoothquark]

I am very tempted to get myself the 1.4 (M) modules when available. Nearly went for it when they were first released. However, I am a newbie and not sure if I have the skills to put everything together. Is there anyone out there who does a build service (for a fee, of course). I would quite like to have 2x monoblocs in one of these chassis (S-3207 Aluminum amplifier case / Enclosure /amplifier BOX/ PSU Case | eBay) measuring 320mm width to match my current DAC (with volume control). Not sure if there would be adequate space for a heat sink though - the SK90 suggested on hifiduino might work? I would also like 12v triggers in and out and I think the recommended PSUs support these? I would be very interested to know if anyone has managed to get monoblocks in a smaller chassis.

Thanks.