Intact Audio

What you state here is mathematically not correct. For a correct filter response both sides of the t-network must be "terminated" with 600 ohms. I showed the effect of different driving impedance in my wp. Everything else than a driving impedance of 600 ohms is less correct. Then we come t...

Dave's comments are correct for me. The LCR has two bridged T-networks. rtfl, where l stands for literature

Walter's view may be valid for near DC conditions.

[quote="Stegie"] Mr. Docali: are you really sure about your white paper? 1. how about the reflected impedance, that will be seen by the LCR in parallel with the termination resistor? The step-up's secondary should be terminated with a very high resistor to present a reasonable reflected im...

something secret or better discuss it here?

Please read my white paper:

https://www.sowter.co.uk/pdf/LCR-RIAA%20Ahlswede.pdf

*deleted*

Sorry, posted in the wrong thread.

Hi, it seems that Stephie is active again ;-) Maybe we might continue our discussion about filament modelling we did some years ago about ER300B. I recently got new tube EML12B and tried to re-work the approach for this tube. Unfortunately I do not have enough experimental data. Only what Jac publis...

Hello Dave! Maybe you have an idea to this issue. I have a compression driver that slighty falls off after 10 kHz in the used CD-horn. The current solution to overcome this in the cross-over is to use an series resistor which levels down the efficiency to adapt the compression driver to the woofers ...

Thanks!

Interesting arrangement. Would you please tell us why you choosed the lower part of the mu follower (what design advantage) as output and not the upper part which yields much less output impedance and therefore could have been used with an lower impedance LCR?

br!
docali

Excellent work and nice looking!

We want see schematics

You should read here about this issues:

[url]http://www.intactaudio.com/forum/viewtopic.php?t=40[/url]

Hello!

The pops are definately related to the D3a operating point shifts. If I remeber well you can read something about this in this forum. I would suggest to NOT use an AVC driving the grid of this tube. Also this tube has in my opinion too less headroom for a line stage.

BR!
Docali

Hello Dirk! You state that the source impedance of the oscillator is about 600 Ohms. In this case it is no wonder that there is less ringing. The 600 Ohms damps the TVC quite good. But what when you drive it with abot 200 Ohms or even 50 Ohms? Then you see the truth :wink: You can do this while driv...

Hello Dirk!

Very nice measurements!

But as such results much depends on the source impedance would you please tell us what was the source impedance of you function generator and what was the schematic for measurement? Was this device loaded?

Thanks!
Docali

Hello! I was thinking already a long time about replacing the big cathode bypass capacitor in single ended stages. Ultra path might be a way. But one big disadvantage is that you need a really large capacitor to avoid the output impedance raise for low frequencies. I observed this for the GCA and UP...

Hello!

I would doubt that this works fine with a normal LCR which has a ten times lower impedance as your RC network.

BR!
Docali

Hello Claus, thanks for your explanation! From my testings I found that you can get a similar error by leaving RL2A out and reducing C2 slightly and adjusting the other values around it. But, and this seems to be the important point, which was not clear to before: you loose the contstant impedance o...

Hello Jazbo8,

i think you are not right. RL2 is the sum of RL2A.1||RL2A.2 and RL2.Cu.

The copper resistance of L2 is RL2.Cu.

Best regards,
docali

Thank you very much, Claus, for sharing this with us! It must have been an huge amount of work! What I do not fully understand actually are the resitors RL1A and RL2A. I suppose that these have to soldered in series to the inductors as additional external resistor? Is there any chance to change the ...

Thank you very much, Claus!

Where will you publish your white paper?

Best regards,
docali

Hi, I did some interesting simulations to show you the difference of LCR and LR. The input impedance of the LCR-RIAA is really very stable and nearly the same over the whole audio frequency range while the LR-RIAA has 10 times more deviations. Maybe this is the what makes the magic of the sound of a...

Hi, if you take a look at my LR-RIAA the phase shift is only about 1-2 degress at 20 KHz. This looks fastastic in my eyes. The high frequencies should be more important here. If someone has time it would also be interesting to see the difference of the impedance with frequency compared for LR and LC...

Hi, so far as I know there was no standard what inverse RIAA was used. I think long time ago they used indeed inductive components but in newer times capacitors only. The phase shift should be different with different inverse RIAA. What sems more important for us is what load sees the source tube by...

Hi, there is a nice script from Dmitry Nizhegorodov which extracts the values for PtPlot from the spice output. Yes, NoC area ;-) But many people say you should use an LCR because it is constant T-network which presents a nearly constant load independent from frequency to the source. I do not know i...

Hi Maturin,

I used LTSpice for the simulations but the graphical software is Ptplot.

What resistance do you want to eliminate? If you go to much down with the inductances you loose much gain.

I opened also an other thread for diff amp with LR RIAA.

Best regards,
docali

Hello,

here you see an example of an fully differential LCR that works quite well with the class A push pull differential D3a stage.

Best regards,
docali

Hello,

does anyone know the correct mathematics how to calculate or incorporate the 4th time constant to an LCR? I did some simulations by trial and error (see attachement).

But there must be a way to calculate these values including the real series resistors of the inductors.

Best regards,
docali

Hi, I would like to show the effect of unbalancing the inputs for a fixed load of 600 Ohms parallel with 1nF. The sum of both resistors always equals 47k. if r1=22k then r2 is 25k. As you can see from the graph the 3rd order distortion is quite the same ofr all scenarios but second order can be trim...

Hello, but I found that you can use a trick which was inspired by Linn Olson and Stephie. Just shunt the middle of the output transformer to the cathodes and feed the amplifer with a slight unbalanced signal. The capacitor only comes into the game if the output signal is not symmetric. In this confi...

Hello, during my studies concerning the usage of the differential amplifier for LR or LCR RIAA I want to present some results to you. The results based on an D3a differential amplifier which was designed totally balanced so that both tubes are in series with respect to the signal. So they are forced...