D'oh. I think all builds so far have been based on the shape. The E/B/C marking to the silk artwork was a late change. Obviously, I was a bit quick on that. I'll put a note in the build guide and post #1. If we ever meet up I owe you a cold one!
GB#2 will get a new board rev.
There's a thread of measured snubber values for many common PS trafos. Unless you're using an exotic, it might be listed there?
@Plott, if you want to try snubbers and don't want to go through quasimodo testing, have a look here to see if anyone has posted results for your transformers:
https://www.diyaudio.com/community/threads/quasimodo-results-only.313202/
Edit: This is the thread ranshdow referred to in his earlier reply.
Also, you can blame me for the E/B/C issue since I suggested that to Randy. The idea was that builders can use the pin designation instead of the shape so that parts with different pinouts (for example ZTX450 vs BC550) can be used without confusion.
https://www.diyaudio.com/community/threads/quasimodo-results-only.313202/
Edit: This is the thread ranshdow referred to in his earlier reply.
Also, you can blame me for the E/B/C issue since I suggested that to Randy. The idea was that builders can use the pin designation instead of the shape so that parts with different pinouts (for example ZTX450 vs BC550) can be used without confusion.
That would be cool 😀If we ever meet up I owe you a cold one!
Ranshdow, Dennis, thanks a lot! There is my Antek 4225 listed, but for 115v pr., mine is for 230v - does it make a difference?
No, I don´t blame you, it was a great idea!
However, now I killed one of the four ZTX 😆
My Monoblocks are built into some old amp chassis that use the DIYAudio store PCB's. Those rectifier boards have snubbers on them. The CL-60's on those amps are in the back corner behind the transformer. On other builds I use my little snubber boards and CL60 boards. What my pix show is my "upcycling" of a pair rawson amps. This is easily rev 3 of whatever has been in this pair. I used the "ain't broke, don't fix it" philosophy on what is already there.
See the link Dennis shared for Quasimodo results. My experience is that Anteks are pretty consistent by model number. So if you see something that matches your transformer in that thread, use those values. Also, I've seen posts that have very specific resistor values. When I measure the value the trimpot when I measure on the Quasi I test with a "close" fixed resistor and test. And it works fine. For example, if the pot says 21.3R, I go to my box of resistors then drop a 20R into the Quasi. Works great, use 20R.
That antek shows 11.8R. 12R will be fine. 14R, 15R, 16R... You get the idea. I wouldn't go lower than 11R. Do you have a big box of spare resistors on hand?
See the link Dennis shared for Quasimodo results. My experience is that Anteks are pretty consistent by model number. So if you see something that matches your transformer in that thread, use those values. Also, I've seen posts that have very specific resistor values. When I measure the value the trimpot when I measure on the Quasi I test with a "close" fixed resistor and test. And it works fine. For example, if the pot says 21.3R, I go to my box of resistors then drop a 20R into the Quasi. Works great, use 20R.
That antek shows 11.8R. 12R will be fine. 14R, 15R, 16R... You get the idea. I wouldn't go lower than 11R. Do you have a big box of spare resistors on hand?
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Yes, most likely a slight one. In Mark Johnson's technical paper on his Quasimodo, he works through that exact scenario for an Avel Lindberg trafo. the Rsnub value he measured was 10R higher at 230V (series primary, shorted for testing) than at 115V (parallel primaries, shorted for testing). I'd link it here but I suspect it's in the beginning of the main Quasimodo thread.That would be cool 😀
Ranshdow, Dennis, thanks a lot! There is my Antek 4225 listed, but for 115v pr., mine is for 230v - does it make a difference?
Thanks Randy. I have no spares (I re-started this hobby just in autumn last year), but I have to order some other parts too, so no problem.
Thank you ranshdow, will take a look.
Thank you ranshdow, will take a look.
Hi,
as D and M don´t have the ZTX450 and it would take 30 weeks or so to get it 😱 I would use the BC 550 instead - but which one is okay? A simple 550, or A, B, or C or doesn´t matter?
Thanks in advance.
as D and M don´t have the ZTX450 and it would take 30 weeks or so to get it 😱 I would use the BC 550 instead - but which one is okay? A simple 550, or A, B, or C or doesn´t matter?
Thanks in advance.
The use of the CL-60 board is different with 230v line (when using two 115v primaries), I made a sketch.
For this version only one CL-60 is needed per board, between 0B and 120A (in the original soldering points of the CLs, just bend the legs of the CL).
I think the value of the cap is unchanged.
Please correct me if I'm wrong 🤔 🙂
For this version only one CL-60 is needed per board, between 0B and 120A (in the original soldering points of the CLs, just bend the legs of the CL).
I think the value of the cap is unchanged.
Please correct me if I'm wrong 🤔 🙂
Istvan,
Is there solder on the CL60 leg on the neutral "0A" leg? See red circle.
You want to wire it up based on the F5 240V schematic. Which looks correct based on no solder at the kink in that thermistor. Am I seeing this right?
Is there solder on the CL60 leg on the neutral "0A" leg? See red circle.
You want to wire it up based on the F5 240V schematic. Which looks correct based on no solder at the kink in that thermistor. Am I seeing this right?
Once again to the snubber resistor. As I don't have the possibility to determine it with a Quasimodo, I checked the results in the other thread and came to the conclusion that the Antek 300-400 VA range requires about 14 +/- ohms. How "bad" would it be if I choose say 14 ohms? Or would it be better not to use the snubber in this case, as Zen Mod wrote?
Istvan, I'm ordering 2 of those donuts today for a project. I've never done the test for 240V applications for Antek, so I just posted a question on the Quasimodo thread to verify the details for hookup for the 240V test.
So I would say this - run without snubbers for the short term. I'll update once I measure and report back. Then drop in your snubber boards.
So I would say this - run without snubbers for the short term. I'll update once I measure and report back. Then drop in your snubber boards.
I wouldn't expect the use of 240V connections on the primary side of the transformer to affect the snubber parameters for the secondary windings. Antek transformers use a very common set of values, Cx = 0.01 uF, Cs = 0.15 uF, Rs = 20 Ω. Close is good enough, don't stress over it.