Carnhill Gapped OT Current Specs

This has been mentioned in several threads before, but I haven’t seen any definitive answers. If I missed it, flog me appropriately.

Neither the Audio Maintenance site nor the Carnhill Design Guide specify max current for their gapped models. Surely someone has found the secret decoder ring for that somewhere along the way. It’s bizarre that they don’t see that as important enough to publish specs.

I don’t have a specific application at this point, but I thought it might be a good time to grab a few while all the Brexit uncertainty has the exchange rate near a 5 year low. I collect transformers like Cher collects wigs.

I’ve used Carnhills in the past for Neve clones, but I’m curious to try them in tube applications.

1166?    that 75 EI gapped core will run at  5500 Gauss  AC for 10 volts at 20 Hz on the primary,

figure the same for DC flux to total 11,000 Gauss for low distortion,

so we have 5500 Gaiss to play with before trouble,

figure 479 Gauss per 10 ma DC current,  from spreadsheet) so 5500/479=11.48 x 10 ma = 114.8 ma

but primary inductance is very low for that model, probably around 1 Henry, you need about 100 times that for a tube circuit,

Thanks, CJ! I wasn't specifically referring to the 1166, just saying that I had used Carnhills before for some Neve clones, and now I'm looking at one or two others that might be suitable for tube preamp circuits. I shoulda been more specific.

I was looking at the VTB 2290 (~10k:600/150 - 4:1) for this.

But even looking at the VTB 2280 (Gapped 1:1) for (mainly) transistor applications, it's the same issue. No current specs to inform specific applications suitability.

I figured surely we'd have the current specs documented for these two by now, but I couldn't find a thread with that info in it.

I’ll ask it a different way. What projects have folks used the VTB 2290 in? What were the current requirements and max levels for those?

Same with the VTB 2280.

Thanks

Equally interested in this topic...


Best regards

//John

I purchased a VTB2290 thinking I would use it on an RCA BA2C build, but now I'm not certain it was a good choice...