Planar Speaker Asylum

Welcome! Need support, you got it. Or share your ideas and experiences.

Return to Planar Speaker Asylum

Planar Speaker Asylum

Can you please elaborate on the protection circuitry?

58.8.70.105

In Reply to: RE: Innersound ESL amp too dangerous for Quad ESL57 posted by GordonT on July 12, 2010 at 02:07:47

What needs to be done as a preventive measure? I understand the panels are quite fragile. Many thanks once again.

Follow Ups:

RE: Can you please elaborate on the protection circuitry? - kentaja 08:07:07 07/12/10 (2)
The panels are not fragile in the least. There is a certain maximum input voltage to the panels, about 33VAC. If the power amp swings more than 33VAC the tweeter panels will arc.

The protection circuit protects the tweeter panels from over voltage conditions. It wires in parallel to the transformer secondary. When the board sees more than 33VAC it clamps off the excess voltage and prevents any damage to the tweeter panels. The circuit has no sonic impact on the speaker since it is parallel to the audio circuit versus series and is 100% reliable.

The bass panels really do not need any protection devise. The gap is wide enough that over voltage conditions are virtually impossible to achieve.

Quad developed the the protection circuit in the late 80's for the ESL63. The same circuit is used for the ESL as well. Prior to the development of the protection circuit the number of power amps that could be used safely with the Quad was limited. This generally meant small wattage type amps. With the introduction of the protection circuit in the late 80's this changed the entire dynamic of Quads and power amps. One can now use any amp they wish without fear of damage.

All the old stories we hear about Quads, i.e. fragile, easy to damage, etc. are history. A properly rebuilt Quad with protection circuits is about as bullet-proof a speaker as you will ever find. I use 300 watt amps with my ESLs and I can guarantee anyone that these huge amps will never damage the speakers. I know hundreds of other Quad owners doing the same thing without any problems.
- RE: Can you please elaborate on the protection circuitry? - GordonT 09:39:07 07/12/10 (1)
  Hi Kentaja, is there a link you can provide to further readings or assembly page of the protective circuitry? Many thanks.
  - RE: Can you please elaborate on the protection circuitry? - kentaja 10:06:45 07/12/10 (0)
    Lots of links and info regarding the original Quad on the internet but virtually nothing about the protection circuit. I don't know why really.
    
    Perhaps it is because prior to the Quad circuit protection schemes generally consisted of in-line fuses, capacitors to roll of the bass, etc. All of these approaches had a rather dramatic impact on the performance of the speaker and purists insisted on no protection device. One simply accepted the limited amp choices for the speaker and its drive capabilities. Or accepted some sonic compromise to achieve some level of protection. None of these approaches was absolutely reliable under all drive conditions and damage to the tweeter panel was still possible.
    
    Some might feel the Quad circuit will also degrade the performance and do not wish to use them. I have never actually talked to anyone that has used the circuit that ever felt there was any sonic impact or change to the speaker in a negative way.
    
    The circuit is nothing fancy, very simple. A full-wave rectifier bridge placed across the tweeter panel transformer secondarys. The output of the bridge has a zener string set to the appropriate voltage, in this case about 2200V. Hit 2200V the zeners kick in and you have a crude voltage regulator preventing anything beyond 2200V. Elegant, 100% reliable under any drive condition and has no sonic impact. Neat! Well it does have a sonic impact when engaged: it sounds like a tube amp clipping.

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors:

VH Audio