I haven't tested mine either, but I also have a potted 1kva from Richard, and am confident in his backing up of his products. It's a shame to hear about others having issues. Not too sure about the design of transformers etc, but one thing I have learned is that something can always go wrong outside of normal testing conditions and these situations can arise in DIY audio often. It's unfair to assume that major manufacturers are exempt from this principle, and from time to time, issues arise. The real testament to the product is how the people stand behind it, and from what I've read/seen thus far, Richard has maintained my confidence in his product. And Justin, thanks again for keeping up communications, your assurances are assuring 
I will also shamelessly plug Otter Box phone cases, another example of people standing behind their products (no affiliation, just a loyal serviced customer)
I will also shamelessly plug Otter Box phone cases, another example of people standing behind their products (no affiliation, just a loyal serviced customer)
I haven't tested mine either, but I also have a potted 1kva from Richard, and am confident in his backing up of his products. It's a shame to hear about others having issues. Not too sure about the design of transformers etc, but one thing I have learned is that something can always go wrong outside of normal testing conditions and these situations can arise in DIY audio often. It's unfair to assume that major manufacturers are exempt from this principle, and from time to time, issues arise. The real testament to the product is how the people stand behind it, and from what I've read/seen thus far, Richard has maintained my confidence in his product. And Justin, thanks again for keeping up communications, your assurances are assuring
I will also shamelessly plug Otter Box phone cases, another example of people standing behind their products (no affiliation, just a loyal serviced customer)
I hope you're not insinuating that DIY audio people are being too fussy here? Their site it says "Primrose Audio exists for audiophile specific requirements."
Is testing for mechanical noise and buzzing outside of normal testing? I wouldn't think so. Not when shipping a large order of transformers a long distance for audiophile use. I wouldn't like a buzzing transformer in any product. I've read that mechanical noise and buzzing can cause a transformer to self destruct. Another manufacturer, which I won't name, once had a similar problem with some custom transformers they made for a kit maker. And for something simple like not dipping them in varnish, wax or whatever it is they use.
Nobody likes recalls but the best way to avoid them is covering everything you think can go wrong the first time.
Good idea.
I thought someone tested his trafo by connecting the secondary to a light bulb. Then, using a variac, the primary voltage was increased slowly. Would this work? I have 2 800 VA trafos from the GB that I would like to test.
Regards,
I have 3 setting in a box, since it will be while. I too would like to find a easy way to test it for piece of mind until I can build. What kind of warranty is there, as if I wait until later this year will Primrose make it right even though I sat on them for a year. I am not to worried as it sounds things will be taken care of.
I wasn't suggesting that anyone was fussy at all... Not sure where you got that. I was suggesting that perhaps they had been sufficiently tested before being shipped, but something outside the scope of normal testing is the cause of of the issue? I was just throwing ideas out there, but next time I will refrain, and just watch.
Its a pretty standard F4 except 30VDC rails. .43mA per device so a total bias of 2.5 amps per channel, 5 amps total bias.
The AC current draw is about 1.9 amps, 225VA at operating temperature.
During the group buy process I specified potted transformers but when they arrived they were not potted, but that is my fault for not following close enough and when I looked up the part # that was on the final order it was non potted, again my fault. Even though they are not potted they shouldn't buzz this much.
They mechanically buzz from cold start to normal operating temperature.
I bought two and will be testing the other one soon.
In my EUVL F5X under load the Sumr’s buzz.
Not excessively, I can only hear it from a couple of inches away.
I kind of expect this is normal, especially considering the current draw.
I'm wondering if someone has come up with a test procedure yet? Preferably something that doesn't need a variac as I don't have one.
Take your rail voltage and divide the bias current your amp will be set at. The number you get is the value of the resistor you should load your PSU with tied from each rail to ground. Just make sure you have adequate dissipation ratings. Probably easiest to parallel multiple 3W resistors. Light bulbs will also work, but will be more e expensive in the end. For most FW amps, which use 22V rails and about 1-2A bias, you are looking at about 10R. You could buy a large resistor or get 10-20 cheap 3w types.
Testing
I finally got around to setting up a test rig for my SumR transformers.
- Variac supplying the transformer (so I can ramp the voltage slowly)
- Secondary output of transformer feeding a bipolar PSU ("+"-ground- "-")
- Output of PSU feeds load of 300-Watt light bulbs (up to 3) wired in parallel
-- I can change load by inserting or removing bulbs.
I am measuring the DC current through and the voltage across the load. Here is what it looks like. Quantitative report to follow, but in an initial test I can hear buzzing from about 3 feet away.
Cheers,
Ryan
I finally got around to setting up a test rig for my SumR transformers.
- Variac supplying the transformer (so I can ramp the voltage slowly)
- Secondary output of transformer feeding a bipolar PSU ("+"-ground- "-")
- Output of PSU feeds load of 300-Watt light bulbs (up to 3) wired in parallel
-- I can change load by inserting or removing bulbs.
I am measuring the DC current through and the voltage across the load. Here is what it looks like. Quantitative report to follow, but in an initial test I can hear buzzing from about 3 feet away.
Cheers,
Ryan
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