Okay, I just signed off on a transformer. Tiger Toroids to the rescue. Yes, prices have increased, but much, much lower than the other quotes. £110 or about 156 USD. This price, I can stomach.
The Tiger Toroid transformers are very good. Make sure you told Stephen Foster
1. It’s for audio ( he winds it with lower flux density in the core)
2. Has a Stabilized core (this mechanically ultra quiet)
3. GOSS band
4. Interwinding screen
5. Cloth wound and double impregnated.
Andrew -
I never knew there is this much that goes into making a great audio toroid transformer. I mentioned 1,2, and 3. By 4, can I assume that's the electrostatic screen? If so, I did mention that to him. I did not mention item 5. I will send him this list. I did mention you. Thank you for the details.
I never knew there is this much that goes into making a great audio toroid transformer. I mentioned 1,2, and 3. By 4, can I assume that's the electrostatic screen? If so, I did mention that to him. I did not mention item 5. I will send him this list. I did mention you. Thank you for the details.
Yes- 4 is the electrostatic screen.
I bought my first 1200 VA transformer from him about 4 yrs ago and it buzzed and hummed so I took it back. He told me I had to spec it for audio, if not, he supplied it to industrial spec - still very good but mech noise etc not really important in a factory.
The stabilized cores have the plastic cover over the tape core impregnated with varnish and baked before they wind the thing so you never get mechanical buzzing.
You will always get a bit of transformer ‘growl’ on a big unit if you get DC on the mains, but this is easy to fix with back to back diodes and caps (see Rod Elliot for example). But Tiger Toroids are still very good in this aspect.
I bought my first 1200 VA transformer from him about 4 yrs ago and it buzzed and hummed so I took it back. He told me I had to spec it for audio, if not, he supplied it to industrial spec - still very good but mech noise etc not really important in a factory.
The stabilized cores have the plastic cover over the tape core impregnated with varnish and baked before they wind the thing so you never get mechanical buzzing.
You will always get a bit of transformer ‘growl’ on a big unit if you get DC on the mains, but this is easy to fix with back to back diodes and caps (see Rod Elliot for example). But Tiger Toroids are still very good in this aspect.
Yes, your comments have definitely helped in this regard. I received a quick response from Stephen and he said the quote given covers all the points that you have posted. I think I mentioned 'Andrew Russell' at least 3 times, and 'audio amp' two times in my communications to him. 😀
Likely mentioning you once would have sufficed. Ha!
I enjoy dealing with companies that know their craft and I'm willing to pay a bit more. Besides, this amp will stay with me over the years so I want it built to last.
I enjoy dealing with companies that know their craft and I'm willing to pay a bit more. Besides, this amp will stay with me over the years so I want it built to last.
Quick update. If you live in the US, Tiger Toroids requested payment via bank wire transfer. My bank declared that they won't perform international wire transfers. So, I did find that Wise will allow me to do this. Now I wait for their confirmation that funds have been received. I paid 159 USD, so I was pretty happy with the price, considering the other quotes received.
Andrew - I've got some leftover SMD thin film resistors from another project. Are there any cons to swapping the thick film resistors with thin film resistors, like the 330k value on the PSU? I'm only familiar with the fact that thin film are preferred for the signal path.
22 mF caps are getting rare for snap-in types. I went ahead and ordered caps made by CDE as the Panasonics are listed as obsolete. It's that or go old school with screw-on types that cost more.
I’ll need to look at that again. Are they just in short supply or has something else changed?
I also went to Panasonic's website and using their parametric search, I received 0 results selecting a min working voltage of 50V and capacitance range of 22 to 27 mF.
Andrew, thanks a mil. For everyone's info, 78-BAT54W-VGS18 is obsolete, but Mouser offers BAT54W-E3-18 as a possible alternative. But I'll leave it to Andrew to confirm it's a good sub. I often commit the error of not digging enough into a datasheet to verify it's an apples to apples match.