SissySIT

[Zen Mod]

then be clever - use rubber anvil and common iron hammer

 

[mikorist]

Cinemag CMOQ 4LPC is quadrifillar (as confirmed by guys from factory) wound thingie , each winding having 27Rdc and 1.5H (measured by your truly )

Difference between Cinemags - CMOQ-4LPC vs. CMOQ-4HPC
If the left and right have this same value they are identical.

 

[dewdrop]

Lol, I had a faint memory that Edcors were such, hence I decided to clarify.

 

[dewdrop]

Today Song measured the 4 Cinemags and sample #3 seemed to be an outlier, will this cause a problem?

 

[KweeSong Lim]

Correction: second row should be pin 3-5 and not 3-6
To be clearer readings are: DC resistance / inductance
So 30.4/12.1 should be 30.4 ohm / 12.1 H

 

[Zen Mod]

compare number of laminates with other ones- it seems as somewhat lossier/looser core than other ones

though , driven with so low impedance , it is a question - will you hear any difference

can you take good picture - showing #3 beside any other ?

 

[chede]

Following the recent thread by XRK971 about using REW for distortion measurements here (https://www.diyaudio.com/forums/sol...-distortion-measurements-rew.html#post5806493), and making use of the opportunity that today is a holiday in our part of Germany, I did some quick measurements of my SissySIT using REW and my Focusrite 2i2.



With the amp cold, you see a clear dominance of the 2nd harmonic, and an extraordinarily low noise floor:

With the amp warmed up, there is really not much difference - minimally lower distortion, minimally higher noise (probably caused by the higher bias current when warm). Note the phase of the second harmonic - 86 degrees, does this mean positive phase second harmonic ?

The left channel is a bit noisier (still nothing to hear with my ear in the Fostex widebanders of my 100 dB/W Jericho Horns), but otherwise superbly matched in level and distortion profile:

I also did a frequency sweep for both channels. For all measurements, the output of the amp was 2.58V, so a bit less than 1W over the 8.2 Ohm dummy resistors. That was the maximum level at the current setting of the Focusrite 2i2, which had been optimized for lowest noise and distortion in loopback calibrating. Could get out a bit higher level, but for "real power" I would have to add a preamp.

Anyway, here are the sweeps, first right channel:

And the left:

Again, I think it shows the very good matching of the two channels. Also, the lowest frequency of the sweep is 16 Hz. You see the rise of the 3rd harmonic towards the low frequencies because of the transformer used in the SissySIT, but I think the CMOQ-4HPC do show very good distortion characteristics towards low frequencies. (It was no really high input voltage, though - 0.707 V).



I found these measurements interesting .

And REW is easier to use for this (following XRK971's ver good intro to using it) than ARTA, which I had used before.



Best regards, Claas

 

[mikorist]

6SN7GTB medium-mu triode vs 6AU6A pentode



Source The Cool Sound of Tubes - IEEE Spectrum

All the harmonics (not just the 2nd harmonic) are similar to the tubes here with Sissy.

Like anything I've ever seen.

Of course the speed on these devices is not visible at this graphics. In nanoseconds for tubes and for THF.

 

[Zen Mod]

well done

it pretty much complies with my own measurements (even if sloppier setup) using ARTA and EMU1212 , later confirmed with my friend's measurements , using AP One setup

really lost in all files , I believe I posted those with AP somewhere

so , it is confirmed , Sissy is working well all around the Globe



(though Germany and Serbia were never too far , someone always breathing to other one's neck )

 

[chede]

 

[Zen Mod]

of course , most important is that your ear-brain combo is satisfied

who needs measurements ....... that's reserved for people who knows what they are doing .....



edit - and yes - 2nd is negative in phase , exactly as I like it most

 

[xrk971]

Very nice work Chede! Thanks for trying out REW for amp measurements.

 

[AKSA]

X/Chede,
Wonderful graphs. This instrument is laying bare the way tubes present sound to the listener. Actually, -55dB H2 for a 12AU7 is very good, the reflection of very high plate resistor. Most guitar amps tend to load down their plates; typically about 2.3-3 times the intrinsic plate impedance. For a 12AU7, that is 15k.
Really good work, thank you!
HD

 

[mikorist]

Again, I think it shows the very good matching of the two channels. Also, the lowest frequency of the sweep is 16 Hz. You see the rise of the 3rd harmonic towards the low frequencies because of the transformer used in the SissySIT, but I think the CMOQ-4HPC do show very good distortion characteristics towards low frequencies.

Whether this is measured with or without the optional Borbely WCF ?

 

[chede]

So far I did not use the Borbely buffer, just the standard version ...


Regards,
Claas

 

[mikorist]

So far I did not use the Borbely buffer, just the standard version ...


Regards,
Claas

Thanks.
Everyone says they have more details without.
Although it's a taste and a loudspeaker thing.
And the measurement shows little differences.

 

[mikorist]

Here are some photo of my build by Zen Mod

 

[Rush]

Power Supply Question

ZM,

In your build, I see a full wave bridge rectifier on each secondary winding of the transformer and the common ground is formed between the power supply caps.

I see this is following the F5 schematic by NP.

I also see that the F5 Turbo (also by NP) uses a full wave bridge rectifier across both secondary windings with the transformer's center two leads going to ground between the power supply caps.

I will post both for comparison.

I am wondering what is preferred and why?

I'm building this amp as we speak. Stuffed boards, back panel completed, laying out bottom plate with power supply.

As you can see I have repurposed a 12 channel Sonamp 1250.

Rush

 

[Eric]

Miko, very nice images of your amp! Thanks for sharing! One detail, though: Please upload images to the forum rather than posting external links that will surely disappear over the coming years. This way, your images will serve as a reference for more people longer into the future.

 

[Zen Mod]

posting with phone,so short... all these pics are taken by Mighty ZM, linked in my recent post in tips and tricks thread.... or just go to SissySIT, another one | Zen Mod Blog