I'm pretty new to all this measurement stuff @andyr . I really am reliant on experts like yourself to help guide noobs like myself with this stuff. I'm just going off what others have suggested. I do think matching FETs (if needed) at operating temp does help ensure the best matches as I found that the Vgs matching measurements are different for MOSFETs at room temperature vs operating temperature (maybe slightly different slopes of Vgs vs temp). Although, with that said, the difference is pretty minimal overall (a few % at most). It is clear and repeatable that power FETS matched at 50°C are not the same "match" at room temp, even if it's not that significant of deviation. I've only been matching power MOSFETs N to N and P to P, not N to P.
I suspect there's not much advantage of measuring the smaller BJT's at operating temp vs room temp as you point out, however, I'm open to input from experts like yourself. Mostly, I just wanted to share how I have been matching power MOSFETs at temperature using the hot plate technique so others can give it a try.
I guess I should also say for clarity that the AN39 doesn't need matched power MOSFETs at all due to only using a single N and single P per channel, so matching power FETs for AN39 is not value added as far as I understand.
I suspect there's not much advantage of measuring the smaller BJT's at operating temp vs room temp as you point out, however, I'm open to input from experts like yourself. Mostly, I just wanted to share how I have been matching power MOSFETs at temperature using the hot plate technique so others can give it a try.
I guess I should also say for clarity that the AN39 doesn't need matched power MOSFETs at all due to only using a single N and single P per channel, so matching power FETs for AN39 is not value added as far as I understand.
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I think you're asking about this part.
| DigiKey Part Number | S9633-ND |
| Manufacturer | Sullins Connector Solutions |
You seem to have misconstrued me as an 'expert', bb! 😀
Thank you for explaining that matching readings at a lower temp ... doesn't hold true for the higher, amp-operating temperature. I suspect I will never be going to your extent, though. 🙁
Hello forum, I am making final choices on parts for my build. I have decided to build a duel mono configuration with two 300VA 24V transformers. I am looking to buy two of the transformers below.
https://www.antekinc.com/as-3224-300va-24v-transformer/
There seems to be an extra ground wire on these, Purple in the diagram below. Would that go to chassis ground our just better left unused.
Any info appreciated, trying to educate myself on this. Thanks.
https://www.antekinc.com/as-3224-300va-24v-transformer/
There seems to be an extra ground wire on these, Purple in the diagram below. Would that go to chassis ground our just better left unused.
Any info appreciated, trying to educate myself on this. Thanks.
Sorry bout that. I guess it's good to know you are seen as knowledge vs the other way around like me
I'm always learning and sharing lessons learned though thanks to this great forum.
That's purple wire goes to chassis ground. That's the extra "screen" that the AnTek AS line comes with to reduce noise/interference. Definitely attach that to ground for best performance. The AnTek AN transformer series doesn't have the screen.
Dolamike,
I assume that you are building the 8ohm version of the AN-39 using the dual rail SLB. The rectified voltage of the 24V secondaries is 33.8VDC. The SLB will have to drop at least 6V (not easy to do) for you to be in the required voltage range of 27V - 28VDC. If you have not purchased these yet I would look at purchasing the AS-3222. It is the recommended transformer rating for the 8ohm version.
PS: I tried the 24V transformers and they did not work for me. I could not get the SLB's to give the required output voltage I needed. I purchased the 22V transformers for my 8ohm version. Unfortunately I have other problems with my build and will be sorting that out soon.
Good luck with your build,
MM
I assume that you are building the 8ohm version of the AN-39 using the dual rail SLB. The rectified voltage of the 24V secondaries is 33.8VDC. The SLB will have to drop at least 6V (not easy to do) for you to be in the required voltage range of 27V - 28VDC. If you have not purchased these yet I would look at purchasing the AS-3222. It is the recommended transformer rating for the 8ohm version.
PS: I tried the 24V transformers and they did not work for me. I could not get the SLB's to give the required output voltage I needed. I purchased the 22V transformers for my 8ohm version. Unfortunately I have other problems with my build and will be sorting that out soon.
Good luck with your build,
MM
@xrk971 can you confirm that I should be ordering the 300VA 22V transformers instead of the 24V. These are from Antek. I was going off of the first post on the group buy thread... I will be using two SLB's in a 4U 400mm modushop case. I just ordered them today... there may possibly be time to change my order given the holiday weekend.
The SLB PSU is also highly recommended - proven to work with single SLB and Antek 600VA 24v (AN-6224) trafo. Should work as dual monoblock with dual SLB and Antek 300VA 24v trafos (or equivalent). Also, a ready to run (RTR) solid state relay (SSR) DC protection is highly recommended to prevent turn on thump and provide safety net for your speakers should something fail.
The SLB PSU is also highly recommended - proven to work with single SLB and Antek 600VA 24v (AN-6224) trafo. Should work as dual monoblock with dual SLB and Antek 300VA 24v trafos (or equivalent). Also, a ready to run (RTR) solid state relay (SSR) DC protection is highly recommended to prevent turn on thump and provide safety net for your speakers should something fail.
Dolamike,
Please refer to the second paragraph of post #1 of this thread - it mentions transformers with 22V secondaries for +/- 27V with the SLB power supply:
Please refer to the second paragraph of post #1 of this thread - it mentions transformers with 22V secondaries for +/- 27V with the SLB power supply:
