Hey there I worked out these calculations using info at the aikens website
1v ac on three secondary wire combinations
primary voltage
35.2:1
impedance ratio
1239.04:1
1239.04x4= 4956k to 4ohm
primary voltage
20.7:1
impedance ratio
428.49:1
428.49x8= 3427.9
primary voltage
14.9:1
impedance ratio
222.01:1
222.01x16=3552k to 16 ohm
Which combinations seem right eg is it 16 and 8 or 8 and 4. Also should I be put 428.48 into 4 or 8? Thanks
output transformer
Moderators: pompeiisneaks, Colossal
Re: output transformer
That's a 3.5K transformer for 4, 8 or 16ohms with a slightly mismatched 4ohm tap.
So I'd hazard an educated guess that it's a Marshall-style 50W EL34 OT. Does it have a 1.5" thick core, approx 3x4"?
Marshall 50/100W OTs have always had an anomaly on the 4ohm winding, although I'd have to pull one out to confirm whether the primary impedance is higher or lower on this tap.
It would certainly accounts for why 4x12 cabs sound so different when wired for 4 or 16ohms, and more so than the difference between series/parallel and all parallel wiring I'd say.
So I'd hazard an educated guess that it's a Marshall-style 50W EL34 OT. Does it have a 1.5" thick core, approx 3x4"?
Marshall 50/100W OTs have always had an anomaly on the 4ohm winding, although I'd have to pull one out to confirm whether the primary impedance is higher or lower on this tap.
It would certainly accounts for why 4x12 cabs sound so different when wired for 4 or 16ohms, and more so than the difference between series/parallel and all parallel wiring I'd say.
Re: output transformer
Thanks it's a little smaller. Core 1", size 3 x 2.5". Secondary has three wires coming out of it. I figure the
primary voltage
35.2:1
impedance ratio
1239.04:1
is between the between the two taps, but maybe I can wire it with a switch to utilize this output also. Any harm in this? Thanks again.
primary voltage
35.2:1
impedance ratio
1239.04:1
is between the between the two taps, but maybe I can wire it with a switch to utilize this output also. Any harm in this? Thanks again.
Re: output transformer
Just realised that you meant only three wires and not three taps.
The closest ratios are the 20.7V and 14.9V windings but the wire common to these will be a tap along the winding, so if you used these for 8 and 16ohm at 3K5 primary (or 4 and 8 at 1K7) you'd swap phase when you switched between the two taps.
Not a huge problem if you use NFB and connect it to the correctly phased tap but otherwise odd.
The closest ratios are the 20.7V and 14.9V windings but the wire common to these will be a tap along the winding, so if you used these for 8 and 16ohm at 3K5 primary (or 4 and 8 at 1K7) you'd swap phase when you switched between the two taps.
Not a huge problem if you use NFB and connect it to the correctly phased tap but otherwise odd.
Re: output transformer
Thanks again.
Last edited by 9 volts on Sun Apr 05, 2009 4:15 am, edited 1 time in total.
Re: output transformer
I have three combinations from three wires. black green (14.9:1), black yellow (20.7:1) and yellow green (35.2:1). THe two with black could share the same ground. I figured I could put in a switch so I could use the green as a ground on 4 ohm setting (disconnecting black) and getting that higher voltage. Is this not done or possible?
Other option- Would 4 and 8 at 1K7 lower the wattage?
Thanks again.
Other option- Would 4 and 8 at 1K7 lower the wattage?
Thanks again.