Zero Feedback Impedance Amplifiers

[mikeks]

Originally posted by Susan-Parker
Hi,

For those that might be interested...

http://www.susan-parker.co.uk/susan-cd-player.htm

Best wishes,
Susan.

Now...this is what i call engineering....

[Susan-Parker]

Hi,

In response to Grahams post about the transformer characteristics I ran a test using the 75 watt transformer with 50 ohm source and 50 ohm load to see what was happening at the top end.


Khz Volts
100 0.7764
200 0.7945
300 0.6768
400 0.2030
500 0.3426
600 0.5228
700 0.5670
800 0.5728
900 0.5531
1000 0.5218
2000 0.5607
3000 0.3793
4000 0.7646
5000 0.8036
6000 0.7004
7000 0.7334
8000 0.6724
9000 0.4179
10000 0.4506
12000 0.7174
15000 0.5910
20000 0.6655
25000 0.3724
30000 0.2701
40000 0.2545
50000 0.3798
60000 0.2264
70000 0.1698
80000 0.2877
90000 0.3855
100000 0.2553
110000 0.1134
120000 0.2350
130000 0.1581
140000 0.1428
150000 0.1013
160000 0.0641
170000 0.1433
180000 0.0611
190000 0.0682
200000 0.0887
300000 0.0647
400000 0.0490
500000 0.0321
600000 0.0466
700000 0.0062
800000 0.0140
900000 0.0374
1000000 0.0045

Notes:

As the setup isn't properly designed for the higher frequencies there are some bumps.

Yes, I can measure to 4 decimal places.

Yes, final measurment is 1 GHz.

Best wishes,
Susan.


(will reply to the various posts tomorrow)

[planet10]

Originally posted by Susan-Parker
a test using the 75 watt transformer with 50 ohm source and 50 ohm load

Numbers converted to a picture

dave

[Jaka Racman]

Hi,

Bas, this might answer your question.

Best regards,

Jaka Racman

[Upupa Epops]

Realy high fidelity, Susan.

[Upupa Epops]

But you are honest - my deep compliment .

[lumanauw]

Is that ALL audio transformer behaves non-linear like that? Even the expensive Jensens OT?

[Bas Horneman]

Bas, this might answer your question.

Best regards,

Jaka Racman

Hi Jaka,

Well thats the answer isn't it

Susan Parker = Audiophonics..

Well Susan...that means that you are famous!!!

Jaka, thanks for finding that.... It is time I started looking past the first page of results by google...
Cheers,
Bas

[enochRoot]

Originally posted by Upupa Epops
Realy high fidelity, Susan.

i might be totally ignorant here, so correct me if i'm wrong. but statistics is the science (or art, really) of making the data say what you want. aren't we generally used to seeing graphs such as this in db (probably because they *look* better)? and then isn't 3db twice (or half) the voltage? again...i might be off a bit on specific details...but hopefully what i'm trying to convey gets through. and basically...it is that this graph seems more drastic since it is provided in volts? aside from the dip at 400hz...wouldn't the 100hz to 20khz performance then be *within* 3db (ie: +- 1.5db) since the range is from about .4 to .8 (ie: a doubling of voltage). if that is correct...then the whole thing can even be within +- 3db, or even less (including the dip at 400hz).

again...my figures might be off...so correct me if i'm wrong. i just thought this when looking at it (and remember statistc courses in college).

[enochRoot]

ran the math...and somehow i was off (i guess 3db isn't twice the voltage?! is it twice the power or something?). anyhow...i show the difference between .2v and .8v to be about 12db. so that would be a +-6db over the whole spectrum, or +-3db save the dip at 400hz.