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Old 18th May 2011, 07:27 AM   #1461
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Quote:
Originally Posted by Susan-Parker View Post
Hi,

Sorry for the delay in replying, only just seen your posts.

I was at the AES UK conference all weekend (Friday to Monday) as well, so still catching up with my correspondence.



If you are using EI lamination transformers then b and c should be okay to get going with.

There is even a line of thought that says a small imbalance is preferable as it keeps the domains "primed" however I would want to do a bit of specific testing to look at this. A lot of the tube based rule of thumb stuff is not really applicable here as the source impedance and number of turns are so much lower.

If you are using toroids then perhaps not so good, as there is no intrinsic gap unlike where the E and I laminations butt together.

When mine come I can mix and match something better for you.

As to your list, the spread is about 2:1 which is what I would expect from my own experience with a sample group.

Best wishes,
Susan.
Thanks Susan for your comment. I've done the 75W EI transformer following your guidelines so a little mismatch in the mosfets would not saturate the core. In the meantime to be safe I ordered and received another set of 12 as I was afraid to be stuck half way in the project. So now I've got 2 sets of 12. I will test the second set tomorrow. I will try to find another close match and the rest I will send to you when you get yours. As I don't intend to keep all of them for myself, I will be happy to leave a few pairs for sale in the future.
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Old 18th May 2011, 07:56 AM   #1462
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Default Zeus Bi - For Digital, Linear Solid state, and Vacum System

I've had this in my mind for quite a while and I try to explain by points:

1- I like high efficiency 2-way speakers with compression driver connected to waveguide. I love the live sound stage that can produce - BUT if not setup properly they can go wild.
2- The design of passive crossover for point 1- may result costly, expensive and difficult to design.

3- DSP cross-over boards (like miniDSP) can be cheaper than passive crossover and can be one off cost as it can be configured and calibrated via software.

4- For point 3- Bi amp is required. The two amplifiers don't need to be wide band, so the output transformer doesn't have to produce wide range of audio frequencies, doesn't have to use special laminations and it can be winded up to be hi-pass and low-pass.

5- Hi pass transformer can protect the compression driver for accidental low freq signal, eg disconnection of input patch lead or switch on-off-off noise. It would not require to introduce capacitor to protect the horn. If not carefully used, a wide range amplifier connected directly to the compression driver is capable of destroying it.

6- Design of Zeus Bi - two identical units with the exception of the output transformer. I leave open the input stage as I would like to use vacum for driver.

7- No time for rest
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Old 18th May 2011, 09:21 PM   #1463
Sheldon is offline Sheldon  United States
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Quote:
Originally Posted by apelizzo View Post
The two amplifiers don't need to be wide band, so the output transformer doesn't have to produce wide range of audio frequencies, doesn't have to use special laminations and it can be winded up to be hi-pass and low-pass.
You can make the mid/high transformer smaller, as you don't need the inductance for LF output. But with the multifilar windings, you won't make the "low pass" version a low pass transformer. No advantage I can see to trying to purposely limit the HF response.

Quote:
Originally Posted by apelizzo View Post
Hi pass transformer can protect the compression driver for accidental low freq signal, eg disconnection of input patch lead or switch on-off-off noise. It would not require to introduce capacitor to protect the horn. If not carefully used, a wide range amplifier connected directly to the compression driver is capable of destroying it.
I don't think that a "low pass" transformer really protects the driver in the same way that a capacitor does. You could still get large transient spikes from a relatively small transformer. That said, if you are using an input transformer, the amp had good immunity to spikes from input connections. It's also pretty much immune to turn on/off transients.

Quote:
Originally Posted by apelizzo View Post
Design of Zeus Bi - two identical units with the exception of the output transformer. I leave open the input stage as I would like to use vacum for driver.
Susan's design uses the input transformer as a voltage amplifier and phase splitter. However, a low impedance source is required to reproduce low frequencies. Her line driver is a buffer. Do you intend to use the tube stage as a voltage amp into a transformer phase splitter?

Sheldon
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Old 3rd July 2011, 11:36 PM   #1464
Stee is offline Stee  Italy
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Default the italian version

of Zeus
(CFP)
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Old 4th July 2011, 12:19 AM   #1465
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Can you translate that for me? I can't read Italian schematics.

se
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Old 4th July 2011, 04:52 AM   #1466
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Hi Susan,

I copied the specifications of the 75W transformer from your website:

==================
Electrical

Inductance of each winding = 99 mH @ 1 kHz, 468 mH @ 120 Hz.

Impedance of each winding = 3.9 KΩ @ 1 kHz, 1.25 KΩ @ 120 Hz.

Inductance between input and output windings (wired for use) = 2.68 H @ 1 kHz, 181 H @ 120 Hz.

Inter-winding capacitance between input and output windings (wired for use) = 9.34 nF

Windings to laminations/frame capacitance (wired for use) = 176 pF

Output impedance in PP NMOS circuit when powered = 0.94 Ω @ 1 kHz, 0.90 Ω @ 120 Hz.
=======================

Can you confirm the inductance 181H at 120Hz? I thought the inductance was less at lower frequency.

Last edited by apelizzo; 4th July 2011 at 05:04 AM.
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Old 4th July 2011, 06:55 AM   #1467
mikelm is offline mikelm  England
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Quote:
Originally Posted by Stee View Post
of Zeus
(CFP)
Hi Stee,

did u build it yet ?

I designed something very similar in spice a few years ago but did not build it so I would be interested to hear how it sounds.
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Old 4th July 2011, 09:18 AM   #1468
Stee is offline Stee  Italy
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Default not yet

but today or tomorrow I will
because I have all the parts

Steve CFP in essence, a high gain super transistor, somewhat similar to a Darlington. But there are major differences. Unlike Darlingtons, there is some voltage gain with Sziklais. Another unique feature is local feedback.
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Old 16th July 2011, 11:13 AM   #1469
Stee is offline Stee  Italy
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Default Zeus 3

Gain inside version
(not only transformer)
Half View of one Channel
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Old 17th July 2011, 11:44 AM   #1470
UnixMan is offline UnixMan  Europe
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Quote:
Originally Posted by Stee View Post
but today or tomorrow I will
because I have all the parts
no news? have you built it?

Quote:
Originally Posted by Stee View Post
Another unique feature is local feedback.
unique feature? I wouldn't say so. Any follower configuration (such as the one used by Susan) does have plenty of it.

As for the next version, it does depart quite a bit from Susan's original idea, which is to get all the voltage gain only from transformers and use active devices (as followers) only for current (power) gain. Yet it may be worth trying. Let us know if you do.

BTW: I don't see it fair to call your variations ideas "Zeus n". The name "Zeus" referred to an audio amplifier is sort of a de-facto "trademark" of Susan. I think only she has the right to call "Zeus n" a variation/evolution of her own design.

Using the name "Zeus" as a form of "citation", together with something which makes it clear that it is a different, derived work may be acceptable (e.g. something like "Son of Zeus" or "CFP Zeus-like", etc). But "Zeus n" isn't. IMHO.
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