diyAudio

diyAudio (https://www.diyaudio.com/forums/index.php)
-   Pass Labs (https://www.diyaudio.com/forums/pass-labs/)
-   -   D1 IV Mosfet (https://www.diyaudio.com/forums/pass-labs/310139-d1-iv-mosfet.html)

maartentje 19th July 2017 02:26 AM

D1 IV Mosfet
 
Hi,

Currently having a PCM63 dac with D1 iv stage, after many years i would like to build another one and see if i can improve. (better power supplies, caps, wiring, pcb layouts etc)

Well i'm at it i was wondering if there would be a improvement possible with a different mosfet. (lower impedance for the dac)
ZVN2210g? Instead of irf610? Let me know your thoughts or suggestions.

Thanks Martin

Zen Mod 19th July 2017 08:41 AM

you can go only up - IRFP240

metalman 23rd July 2017 07:40 PM

I built a D1 I/V stage using ZVN3310's. I dropped the supply rails to +/- 22V on mine. It sounds pretty good to my ears, but I've never heard an actual D1 to compare.

Sabrosa 1st August 2017 02:48 PM

I actually posted yesterday asking for suggestions for high transconductance surface mount MOSFETs to use in an ES9038PRO-capable D1 I/V stage and just came across this thread this morning.

I've put together a list of devices to test for transconductance under the operating conditions of the circuit and would love any recommendations for additional MOSFETs to add!

The supply rails are +/-6V, operating current is 1.09A, and max gate threshold is ~4V, so I've mostly focused on MOSFETs at or around logic level.

Here's the list so far:

IRL40S212
IRL40SC228
IRL60S216
IRFS7430PbF
IRFS7534PbF
IRF2204S
PSMN1R5-30BLE
PSMN3R4-30BLE
PSMNR90-30BL
CSD19535KTT
CSD19536KTT
CSD18510KTT
CSD18542KCS

Nelson Pass 1st August 2017 07:44 PM

Transconductance seems to be a vary important criterion for you.

Since this is a Common Gate Mode circuit, transconductance is the
reciprocal (mathematically and literally) of the input impedance, we
ask the question - what input impedance are you trying to achieve
and why?

Sabrosa 8th August 2017 09:55 PM

Thanks Nelson, appreciate you taking a look.

In order for the ESS DACs to stay in current-output mode they need to be loaded into as close to a virtual ground as possible. Ideally in the mOhm range, given the low output impedance of the DAC (~200R). Higher input impedance pushes the chips into voltage-output mode and prevents you from reaching the data sheet DNR and THD specs.

I suppose a better way to frame my question and search might be, given that I need a high transconductance MOSFET with a low-ish gate threshold voltage, are there any other audio-beneficial characteristics I should be considering? Or specific lines of MOSFETs known to be audio-friendly when in the signal path under these conditions?

2 picoDumbs 8th August 2017 10:36 PM

Maybe 2sc4793 instead of mosfet

Nelson Pass 8th August 2017 11:22 PM

I would be interested in seeing any data that shows the performance
degradation into loads greater than 0 ohms.

2 picoDumbs 8th August 2017 11:30 PM

Quote:

Originally Posted by Sabrosa (https://www.diyaudio.com/forums/pass-labs/310139-d1-iv-mosfet-post5152498.html#post5152498)
I suppose a better way to frame my question and search might be, given that I need a high transconductance MOSFET with a low-ish gate threshold voltage, are there any other audio-beneficial characteristics I should be considering? Or specific lines of MOSFETs known to be audio-friendly when in the signal path under these conditions?

TO264 Lateral Mosfet.
Probably want to bias around half an amp.

Maybe also worth checking out SiC Jfets in to247 package. United SiC

abraxalito 8th August 2017 11:58 PM

SSM3J355R has typical gm in excess of 10S @ 1A however it would need cascoding as its limited to 1W dissipation being a thermally enhanced SOT-23. Oh and its also a P-channel device. Threshold voltage <-1V.


All times are GMT. The time now is 12:51 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 17.65%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio

Wiki