Problems with ribbon tweeter and ZEN V4

[Selfmade]

Hello Mr. Pass,

I finished my ZEN V4 three weeks ago. It sounds wonderfull with 93 dB/Wm 2way (PHL 2460, Raven R2) speakers with passiv XO.

Today I was building a biamping sytem with the ZEN V4 for the Raven R2 and the ZEN orig. for the PHL. I use a 24 dB/oct. active XO from Thel.
The sound is much more better than the passiv version.

But there is a problem. Every time I switch on the ZEN V4, the ribbon of the R2 beginns to swing. The swinging ends after one minute. When I switch the amplifier off the ribbons swings again for some seconds. There were no problems with the passiv version with a capacitor as high pass filter for the Raven.

What can I do? A soft start modul is not enough, because the swinging lasts one minute.

Thanks Mr. Pass for the circiut of this ZEN amp. It sounds really great.

regards

Günter

 

[Nelson Pass]

I have run the Zens into the R2's directly without noticing
this effect. As the impedance of the R2's is quite low
(about 2.5 ohms) we might be seeing resonance between
the inductance of the R2 transformer and the output cap
of the Zen.

Alternatively, you might also be seeing some high Q effect at the
low frequency rolloff point during turn-on of the Zen because
of the value of the coupling cap at the output of the buffer, C2.

If the rolloff of C2 is much lower frequency than the output
cap, then you can see this, especially with an inductive low
impedance load.

Try lowering the value of C2 to see if this affects the swinging.

Let me know what you get.

Or try a 20 uF film cap in series with the R2.

 

[Nelson Pass]

(Later)

I went home and checked the impedance of the R2. It seems
to be less than an ohm at low frequencies, this is causing
the output rolloff.

I would definitely recommend the cap in series with the
R2.

 

[Selfmade]

Hello Mr. Pass,

thank You for your advice.

I have tested three possibilities:

1. lowering the value of C2 from 10 m to 4,7 µF.
No positiv effect.

2. using a film cap (10 µf) in series with the R2.
No more swinging!!!

3. using a 3 ohm resister in series with the R2.
only a little swing when I swith on the ZEN V4.


Because off the active XO I see no sonical disadvantage using a resitor in series with the R2. This could be better than using a film cap in series with the R2. Isn´t it?

What would you recommend?

What alternativ tweeter would you recommend.
ESg3 (8 ohm) or Newform R30" (12 ohm)


regards

Günter

 

[Nelson Pass]

The Raven 2 is a sweet tweeter, although I only drive it
down to about 6-8 KHz, not the 1.8 KHz that it is supposed
to go down to.

Given that restriction, the TAD PTR9 is better yet, but costs
about 4 times as much.

Regarding the R2, my recommendation would be a high
quality 20 uF cap, but you know, it won't hurt anything
to either leave it as is or insert some resistance.

 

[Peter Daniel]

I like my Raven tweeter too, but it is fragile indeed. The third order filter at 7k I'm using, barely allows me to play it at satisfying levels. I have to admit that I had to replaced ribbon foil twice already.

 

[Nelson Pass]

Obviously you need an "Industrial" strength tweeter.

(wink wink nudge nudge)

 

[Stefano]

maggies

I hope is the right place to ask it , but i want to know if the zen with aleph current sources is the right thing to drive the little maggies. tank you all

 

[Nelson Pass]

The little maggies do not require much damping factor,
and you don't have to worry too much about deep
bottom end, but they do like power, and you might
find that the Zen is not powerful enough.

 

[Peter Daniel]

(wink wink nudge nudge)

Industrial strength tweeter for industrial strength music?