I'm collecting some info about power and output transformers on different amps because I've found a trafo maker near me and this will let me save some money so try different configurations and find what i really need for my amps.
By now I've found classical Dagnall specifications:
Dagnall C1998 38x38mm on EI M6 core:
- 16-0 ohm secondary (parallel): 120 turns x 0.76mm AWG21
- primary: 2 x 620 turns on eight layers x 0.45mm AWG26
- 8-16 ohm secondary: 35 turns x 1.18mm AWG18
- 4-8 ohm secondary: 25 turns x 1.18mm AWG18
- 0-4 ohm secondary: 60 turns x 1.60mm AWG15
Dagnall C2668 on 38x40mm on EI M6 core (500-650pF primary to secondary capacitance):
- 0-4 ohm secondary: 60 turns x 1.76mm AWG13
- 1/2 primary: 620 turns on four layers x 0.45mm AWG26
- 4-8-16 ohm secondary: 25+35 turns x 1.18mm AWG18
- 1/2 primary: 620 turns on four layers x 0.45mm AWG26
- 0-16 ohm parallel secondary: 120 turns on two layers x 0.75mm AWG21
Dagnall C3070 32x60mm on EI M6 core:
- 1/4 primary: 310 turns on two layers x 0.45mm AWG26 (B+ to half A2)
- 0-2 ohm secondary: 40 turns x 1.76mm AWG13
- 1/2 primary: 620 turns on four layers x 0.45mm AWG26 (B+ to A1)
- 2-4 ohm secondary: 20 turns x 1.76mm AWG13
- 4-8 ohm secondary: 25 turns x 1.18mm AWG18
- 8-16 ohm secondary: 35 turns x 1.18mm AWG18
- 1/4 primary: 310 turns on two layers x 0.45mm AWG26 (half A2 to A2)
Soldano SLO100 OT is similar to C3070, except is 32x50mm and has an higher primary impedance.
Now about Trainwreck specs, where I need more hints:
http://ampgarage.com/forum/download/file.php?id=10100
Moose wrote:The vintage spec is identical to the Pacific in Glenn's amp -- on M19/26 steel, same lams, same wind, same tap, etc. The difference is noticable in the feel of the amp, especially in the ease of sustain, as well as in the midrange focus and distortion. It's smoother vs. the crunchier distortion on the original M27 version.
Moose wrote:I did a touch of experimenting and that's close to the difference in the 5200 and 6600 ohm taps. Even with the M27 steel, that was the difference with the M19 giving you more bass whump at the attack, but the higher impedance smoothing things a touch. In M19 you can get some of that bassier sound of the stancor by using a liverpool tranny -- it's not so much MORE bass, but there is a change in character on the low end. Hard to describe as I didn't A/B, I actually swapped trannies on my personal amp.
Moose wrote:M6 is not the best steel if you want to chase Franchesca tone. I've got a stancor style in M6 here and it's clear, sounds bitchen with KT66, but the El34 sound is too sizzly and it doesn't thicken up when pushed.
M6 is a grain-aligned steel that is particularly good at resisting saturation, which makes it a technically great steel for audio transformers -- if you're a hi-fi engineer who is looking for clean. To get better saturation performance than M6 -- i.e. more flux with less time in saturation when overdriven, meaning more linear phase and frequency response and less harmonic distortion -- you have to actually go to much more expensive materials like nickle.
However, you can't get the Franchesca tone without the saturation and accompanying alinear response. So, if you're cloning an express circuit, M6 is bad.
http://www.mif.pg.gda.pl/homepages/tom/transfor.htmVacuumVoodoo wrote:P=50W, FPBW: 70-12000kHz, Raa =8k, ZL= 4,8,16 Ohm
If you've done 15% of your homework you will also specify max primary IDC. Another 15% of homework will tell you to specify what power tubes will be used and their operating conditions i.e B+ in addition to I(bias)
Next 10% of homework will teach you to specify how windings should be interleaved, choose core material, what diameters of winding wire to use, how many turns per section etc. If I understand correctly what you're saying you already know this.
The remaining 60% you'll have to "discover" on your own. Hint: just as you can draw load lines for tubes and graphically analyze distortion characteristics of a particular gain stage or push-pull pair so can you draw load lines for magnetic circuit i.e. a transformer on the set of hysteresis curves for the core you intend to use and analyze distortion characteristics in analogous way.
When you will have done all this and discover how to match tube characteristics to magnetic properties of core material to design a transformer that together with your chosen power stage design will produce required distortions you will be able to give a manufacturer very exact and detailed specifications. 95% of manufacturers will then say you don't know diddly squat about transformer design.
http://www.cfd.tu-berlin.de/~panek/cykin/cykin1.zip
http://www.cfd.tu-berlin.de/~panek/cykin/cykin2.zip
http://www.cfd.tu-berlin.de/~panek/cykin/cykin3.zip
VacuumVoodoo wrote:You should be more concerned with laminations and isolating lacquer thickness, carbon and silicon content, cold vs. hot rolled steel, post roll heat annealing