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-   -   Does anyone know the output transformer specs of the... (http://www.diyaudio.com/forums/tubes-valves/103980-does-anyone-know-output-transformer-specs.html)

jarthel 22nd June 2007 04:27 AM

Does anyone know the output transformer specs of the...
 
Audtionote P4 monoblocks?

Here's the schematics: http://www.simpletube.com/databank/S...ioNote_P3M.gif

Please info such as primary impedance, power and current rating?

Thank you.

lt cdr data 22nd June 2007 10:23 AM

well, its a 300b push pull

so anywhere between about 3k and 7k,

3k for class AB, cool, over 30 watts, depending on psu/b+
5k for in between, probably about right
7k for all class A, which will give about 16 watts.

tx will be about

30 watts or so,
80ma per tubeish

I would say 5k5,giving about 22 watts or so, 50 watt core, maybe 30, 200mamps

that's just an educated guess

actually ,sorry, I think its a pse which makes it a little more predictable.

probably 1k2ish....



power? 20 watts?

lets see....

calculations give 11 watts at 1k5 impedance, 12 watts about 1k2

distortion is lowish, 3-4%

each tube running at 85 milliamps, generating about 65 volts across the cathode resistor, so 170milliamps plus

B+ is 420 volts, which gives 330 volts across the output tube, and dissipating 70% of the 300b;s rated power.

so I reckon you are looking roughly at a 20 watt single ended tx, with around 1k2 primary, 10-15 henries, winding resistance? 150 ohms? which is rather high, >10%, better around 80 ohms

that's beter:rolleyes:

Dave Cigna 22nd June 2007 01:56 PM

Actually, it's parallel SE. The way it's drawn had me fooled at first too.

jlsem 22nd June 2007 05:02 PM

From the Audio Note website:

"Group C, bifilar wound double C-core output transformer with 1K25 primary impedance and 4 & 8 Ohm secondaries for 300B or 2A3 in parallel single-ended operation, 180mA standing current, 50 watt, , Size 115 mm x 102 mm x 136 mm, mounting holes centre to centre 87 mm to 84 mm both sides."

This isn't necessarily the one used in that amplifier, but it's the only one they sell for that purpose, so it's still a good bet.

That would also make a good OPT for a 6528 SE amp.

John

lt cdr data 22nd June 2007 06:24 PM

aha, ok, I have got some info. on older audionote transformers

I reckon its either a trans 115 or trans 120, it won't be an expensive one on this amplifier.

both are 1k25 primary,

inductance is listed as being 6.6 henries for both, can't guarnatee that's correct

turns ratio 12.5:1
30 watts or 50 watts
130 or 180ma, so its looking like the trans 120 at 180ma
and primary DCR of only 29 ohms
and secondary of 0.5R

so the calcs for that show

about 77% standing dissipation, 31 watts

cathode volts of about 70 at current of 88ma
16 watts output, giving about 5% 2nd harmonic

at the operating point, plate resistance is around 344ohms, so for the inductance calculation, we get

270 ohms = 2x pi x F x 6.6

giving a -3db point of 6.5 hz for low signals

and 30 hz for full power

that sounds about right I would say.

for your voltage swing, its 142 volts rms

I guess M6 silicon steel, saturating at around 16,000 gauss

means your ac flux should be between 1/3 and half that, so 5,000-8,000 gauss

which means for you ac calculation, say

8000 gauss= 142x10 to the 8 / 4.44 x freq. x core area x primary turns

get the core area, and sat. freq, and you have the primary turns

at an educated guess I reckon the core area will be at least 16cm squared.

so for 5000 gauss and that core size, I get about 2000 primary turns

and 8000 gauss around 1200 T

using 20 hz.

presumably then, it runs out of inductance at 30 hz before the core saturates at 50 watts if that's how its to be interpreted?

that sounds very plausible.

more light on the latter is needed....I don't know everything

pretty textbook as you would expect

lt cdr data 22nd June 2007 06:55 PM

all you need is an air gap, and an interleave, and go and build it, get it built, or buy one similar:dead:

jarthel 22nd June 2007 11:34 PM

Quote:

Originally posted by jlsem
From the Audio Note website:
I was looking at the audionote site and I cannot find it. Can you give me the URL?

Thank you :)

jarthel 23rd June 2007 12:27 AM

Quote:

Originally posted by jlsem
From the Audio Note website:

"Group C, bifilar wound double C-core output transformer with 1K25 primary impedance and 4 & 8 Ohm secondaries for 300B or 2A3 in parallel single-ended operation, 180mA standing current, 50 watt, , Size 115 mm x 102 mm x 136 mm, mounting holes centre to centre 87 mm to 84 mm both sides."

I somehow get the feeling that 50W for a PSE 300B is somewhat overkill. right?

Thanks again

jarthel 23rd June 2007 12:51 AM

I have found some info while searching the net that the amps are rated 18W/channel. Would it be okay if I use a 20W transformer? Or must I use 25W to be safe.

Audionote Conquest which is also a PSE 300B uses 1.25K/50W. Is there a reason for using a 50W transformer in an amp capable of only 18W?

lt cdr data 23rd June 2007 09:51 AM

I don't have online info, its in an old audionote listing.

I don't know what the 50w rating means, core size? does seem a bit on the large side, but I think audionote use large cores and fairly low primary turns.


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