Carnhill vs OEP

Did some sweeps as a compliment to Joe Malones transformer tests
http://www.vintagedesign.se/diy_reseach_frames.htm

You'll find the sweeps under DIY Corner

Hope this helps a little bit :grin:

Thanks ! :thumb:

Thanks Tekay!

Nice results. I have been a fan of OEP, I have a pair of the OEPA3E in my FETboys (Hamptone JFET PRE) and a pair of the OEPA2E wided 2:1 on a pair of Spectra Sonics 101.

At half the price of the Carnhills I don't think they did too badly, esp. the OEPA3E. For those in Europe and Africa they are great value fro money through Canford.

Cheers

Matt

Thanks again. Some small questions:

#1
the loading as you mentioned in the table, is that in addition to what's already present in the 1290-circuit ? Or does it represent the total loading of the secondary ?

#2
just curious, where did you 'leave' the 1290 ? At the output ? (so the plotted freq-graphs are of a total 1290)

#3
The JLM-page mentions the A3E used with the secondary windings in parallel and in your table I saw a single secondary was used. Just curious, what are your thoughts on this ?

#4
If you happen to have done some listening, what were your impressions ?

Thanks,

Peter

Hi! All!
1# Yes the loading is an extra resistor over the transformers secondary

2# All measurements where done through the whole 1290 circuits with an extended gainrange switch set to 0dB ( 1063 gain )

3# Forgot to test A3E with the secondary windings in parallell, but I think Per Lundahl said neve parallell the secondaries.

4# No real listening tests yet, justy checked that the low and high wasn't missing when connecting a CD to the input.

My DIY page has been resting long enough now so I hope to update PSU, relaunch the 1290 in a new version and more.

Keep on soldering!!!

TK,
Thanks for the test!!!

regarding the A3E, by single you mean using just one of its secondaries??



:guinness: :guinness:
Fabio

Hi Bauman!
Yes one secondary winding, Will sweep with secondary windings in parallell later this week!

[quote author="Tekay"]My DIY page has been resting long enough now so I hope to update PSU, relaunch the 1290 in a new version and more.[/quote]

Yipeee!!! :green:
My 1290 are still sitting on the bench. :roll: A 24V/48V psu from 24V AC would be cool!
Hey, when comes the CL1 Mk2 DIY update? :wink: :green:

Thanks for the nice sweeps!

Forget the 20 to 20K.
Most any transformer, even some power and control voltage transformers, will measure flat during 20-20.


Do some plots in the problem areas, like 0 to 10 hz.
and 20k to 1 meg hz.

I do not see any resonant peaks past 40k?
Try some unloaded sweeps from 40k to 250k.

You have inductance meter?
Short secondaries and measure pri inductance for all those guys.
This is your leakage.
You can put a cap meter from any pri lead to any sec lead and get a capacitance comparrison also.

tekay wrote:

My DIY page has been resting long enough now so I hope to update PSU, relaunch the 1290 in a new version and more.

Click to expand...

yipee!! a 24V/48V PSU from 24V AC would be cool! :green:
oops! frank already wrote that...but i second it!

thanks tekay!! :thumb: :guinness: :guinness: :guinness:
-grant

[quote author="CJ"]You have inductance meter?
Short secondaries and measure pri inductance for all those guys.
This is your leakage.
You can put a cap meter from any pri lead to any sec lead and get a capacitance comparrison also.[/quote]
Have LCR-meter since recently - can do at 120Hz & 1kHz. Would that make sense ? Can measure both OEP-types for L & C.

Thanks Thomas for the info. :thumb:

[quote author="Tekay"]Hi! All!
1# Yes the loading is an extra resistor over the transformers secondary

2# All measurements where done through the whole 1290 circuits with an extended gainrange switch set to 0dB ( 1063 gain )

3# Forgot to test A3E with the secondary windings in parallell, but I think Per Lundahl said neve parallell the secondaries.
[/quote]It'd have to change the termination then as well, correct ?

4# No real listening tests yet, justy checked that the low and high wasn't missing when connecting a CD to the input.

Click to expand...

Keep on soldering!!!

Click to expand...

And measuring & thinking (we all) ! I feel this thread can be a nice addition to the already very nice JLM-TX-info :wink:

Regards,

Peter

120 and 1000 is cool.
1000 was standard back in the day, so you may want to use that.
It' s all relative.

[quote author="CJ"]120 and 1000 is cool.
1000 was standard back in the day, so you may want to use that.
It' s all relative.[/quote]
Time for sleep here now, but I'll measure those A262A3E & A262A2E OEPs tomorrow evening - stay tuned :thumb:

CJ.
The sweeps was only made to show the frequency response, I leave the rest to people who knows how to do it.
The sweeprange was 10Hz to 96kHz and it wasn't a meant as a competition between Carnhill and OEP just a frequency response performans test.
Got peaks in the 20kHz-40kHz range without the loading resistor and or zobel, but just 2-5dB peaks

thanks tekay!

If possible, Id like to see a sweep of the A3E with the secondaries in parallel, loaded with a 6k load, like joe malone suggested.

/J

[quote author="CJ"]

You have inductance meter?
Short secondaries and measure pri inductance for all those guys.
This is your leakage.
You can put a cap meter from any pri lead to any sec lead and get a capacitance comparrison also.[/quote]

Oh, small question for a TX with dual prim & dual sec windings, how to do this leakage measurement the best ?

Uh, nice:
http://www.voltech.com/Downloads/ATAppNotes/104-105-0-5A.pdf

For now will simply proceed with prim & sec each in series (ha & then those secs shorted), but just suggest what's actually the 'official' way in such a case.

either way, dosen't matter
as long as you do the same for all
that way we see comparrison of leakage

Here some OEP-measurements:



Signals before & after TX look fine on scope.

However, I can't get the Ls & Rs measurements to agree with the D (1/Q)-indication on my LCR-meter,
so left those inductance measurements out for now.

Maybe we can solve that right here right now ?
It's about the measured DCR (not) being equal to the Rs following from

D = Rs / (2*pi*freq*Ls) = 1/Q

It goes fine for single inductors, but as said for a separate TX-winding
I can't get the measured DCR agreeing with Rs (for a series R & L equivalent circuit).
I must be overlooking something TX-related... :roll:

I know there can be some tricky things going on, but as said, the testsignal
as generated by the LCR-meter looks fine before & after the TX.
BTW, that signal is a on/off sinewave (say one second on, one second off)
with a swing of 1.5Vpp (unloaded).


Bye,

Peter

Cool!

Might want to check leakage from sec to shorted pri.
I expected a lower leakage inuctance from the lower rastio trans as there are less turns.
But maybe since the pri's are the same turns, they read the same for both.