Romy the Cat wrote:

Romy the Cat wrote: ...To substitute SL600 original tweeter with anything else, would it be Revelators, Diamond or made from Faberge Eggs is like to make a movie with Humphrey Bogart and ask busboy form a nearby Chinese restaurant to re-record the Bogart’s dialogs. The SL600 tweeter with pure copper dome and phenolic suspension was probably the most perfect tweeter even was made (sonically), with only disadvantage in sensitively department.

Romy can you tell us what you thought of the Zu loudspeakers, I spent an afternoon in their company recently, they were being used with a 25 watt PP Luxman, I believe.

Keith.

You have an opinion on most things ( whether you have heard them on not ) I thought you would jump at the chance to pronounce on the Druids, seemingly not.

Hi Paul,

Could you help me understand what you mean?

Are you saying that even without a high-pass filter, a <8" driver has an imbalance of 'harmonic development' above and below 150Hz... and that this is not the case above and below 400Hz?

If we go for a <8" driver high-passed at 150Hz, could we not compensate for this phenomenon by having a >8" driver low-passed at 150Hz?

In any event, the Druid has a 10" 'full-range' driver that I'm hoping will be quite 'happy' down to 150Hz. Strangely, my upperbass driver will be a 7" driver (the one in the WB-Chimera's upper chamber)! Perhaps not the best solution for 70-150Hz duties... but I'm just working with what I have. Although no doubt challenged, the 'harmonic development' will presumably at least be even between 70-150Hz.

Mani.

Romy the Cat wrote:

manisandher wrote: As I alluded to before, I'm at risk of becoming a DSET convert - it's all very well having a nice low-powered amp, but what the hell do you use with it? Are there any decent high-sensitivity FR speakers out there? Or is this simply physically impossible? I do not know. My local guy told me initially that Zu Druids are 110dB sensitive and high impedance. Hearing it I lent to him my full-range Melquiades to try. He has a few other PP and SET amps, so I thought with 110dB sensitivity and high impedance my no-feedback Milq will be running the show. He kind of liked Milq initially but what he reported was not what I expected and it in my view it was confusing.  Another day I visited him; we did some changes in Zu Druids (more need to be done) and tried a few different amps. It was clear the Milq was not the best candidate as it was dynamically straggling to drive Zu Druids. He has some kind of 30-40W tube PP that did much better job. That made me to do only and to learn that Zu Druids are 101dB. In really it might be even less as those hi-fi companies lie for am few dB and it become a common practice. Furthermore in LF the Zu Druids have perhaps 90dB efficiency as then use port and what the port begin to become affective the no-feedback SET would die. I still, can’t figure out Zu Druids. I would heavily highpass it to use with SET or drive it with 50W SET, preferably with feedback. Something the level of Lamm ML1 might be a good candidate for them to try. If you look out there then you will see anybody promote Zu Druids as some kind of wonder that might be perfectly used with flea-power amp. This is why people attracted to them I guess. However, I do feel that it is a bit stupidity to promote Zu Druids as a SET friendly loudspeaker. It might be a good speaker for the money but not for use with SET. In 2006-07 the industry whores created a lot of hype about Zu Druids. I do not know if it was worthy or not but I know that fact that they were pushed as “$3000 solution that can be driven by SET full-range“ was very inaccurate. The Cat

KLegind wrote:

Initially I thought the Zu might be an interesting speaker in the context of tube amplification, however I tried the fullrange driver approach and I have misgivings about it... Anyhow, the industry rag Hifi World (with whom I have a hate/love relationship) did a review of the Zu a few years ago. The content of said review I think is irrelevant, however there were measurements of the speaker done by Noel Keywood and they showed a much lower sensitivity than advertised. I believe it to be in the low nineties. The frequency response also looked suspect. I see if I can find the review when I get home from work. best PS. I do not express any opinion on Zu sound as I am unfamiliar with it. In a certain context it might be good.

manisandher wrote:

At some point I'd like to start a thread asking for ideas on how to go about setting up a DSET / multi-horn system. Are there any threads here that I should read before doing that?

It would be in a direct contradiction with my main audio doctrine. If you are willing to pursue the DSET/multi-horn system then I think it shall be no external knowledge that shall drive you. You need to categorize those very well-defined shortcomings in your current setup that might make your audio-practice uncomfortable and to ask yourself if the DSET/multi-horn idea will address those very specific shortcomings.  Otherwise the whole idea of “better audio” in my view has no sensible meaning and become just eternal chasing of own tail.

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=432

Firstly, thank you to Montepilot, Paul S, KLegind, zanon and Romy for all your thoughts on the Zu Druids.
I recently tried high-passing the Druids at various frequencies and using a pair of Wilson-Benesch Chimeras and various amps for LF and upper-LF duties. The results were certainly not to my satisfaction. Although the Druids seemed happy being high-passed >150Hz (or at least happier than normal), I just couldn’t get any decent integration below this. It was a bit of a mess really, with the other equipment I was using.
So, I currently have the Berning Siegfried driving the Druids FR for now. At low-to-moderate volumes, the sound is very listenable – not particularly engaging, but listenable nevertheless. I’ve tried a number of different 300Bs (EAT, KR and WE) with the Siegfried and have settled for the WEs, as I feel they have the best tone and depth in the mid-range.

Romy the Cat wrote:

You need to categorize those very well-defined shortcomings in your current setup that might make your audio-practice uncomfortable and to ask yourself if the DSET/multi-horn idea will address those very specific shortcomings.  Otherwise the whole idea of “better audio” in my view has no sensible meaning and become just eternal chasing of own tail.

Mani,

I would leave the subject of DSET/horn setup for another thread and would drop a few words about Zu Druids. They are not the speakers that I would ordinary comment but since I have a local guy with Zu Druids and I had a chance to hear them a few times I think it would be worth to drop a few words. I will comment only about one area – the Zu Druids’ bass.

The Zu Druids’ bass is a freaky animal. If course Zu Druids has no bass in normal since but if whatever bass the Zu Druids is able to do would considered as bass then I was wondering why Zu Druids behave so strange. The guy who use the Zu Druids live in center city and use power right from the wall – so it is difficult to talks about absolute terms as sound changes each hour but some feeling about the Zu Druids I would pass. I did not measure Zu Druids properly, did not have them in my own and my view about Zu Druids might be a pure conjecture. But I heard the a few times and some of my sensations about Zu Druids do make sense to me. So, here it comes….

Forget all that you know, read, and heard about loudspeaker design for the sake of understanding and feeling the understood we need to embrace a totally different view. If you visualize a relationship between driver and enclosure (including port) then there are mass, there are velocity and there is volume (including port). The velocity and volume are fine let it be but let to look only at mass. The question would be the mass of what? Let to do even more idiotic and apply an abstract of General relativity to the example. What is mass in loudspeaker? If a cone has 200g for instance and the suspension has compliance X then we can presume that the dynamic mass would be 200X, right? Well, I would reply: it would depend from what frequency you are. If you are 100Hz then you have no problem to push 200X but if you 100Hz then to develop the force 200X at 100Hz is not much harder but you cave harder contra-forces of the moment. So, let introduce mass not as absolute kg or pound but as relativity to the “pushed” frequency, let measure it in mass per wave length – m/wl, or juts MWL. Ok, we have for 1000Hz a speaker cabinet has 150MWL but for 50Hz it has 10MWL. This is what happen with light speakers that starting from some frequency begin to drift upon own mass deficiency. The Zu Druids are one of the examples – the are light, the are resonant like hell (play with gasket bet the driver and box – you will see) and then as soon the reach some upper midrange then flip over and stop act as mass-scenic system.

Let even forget about port – it is a part of the big picture of mass killing. You are 50Hz, you come to the driver, the speaker has velocity but has no mass – what you do – you tell to the peoples that send you – “fuck it; there is nothing to do here”. It is exactly what bass does in the Druids – it destroys itself and modulation of this distraction poison the sound of Druids lower end. I know, the people with engendering background would read it as feel that it all full of crap but there is a detail: the know nothing about Sound but I do. They design the Druids but I am trying to explain why Druids sound very bad in bass.

So, what can we do? We need to add virtual mass to Druids but only at LF. I have a solution how it needed to be done but first I would like to say why I feel my solution shall work. I was observing how Druids’ bass reacted to different amps. Particularly interesting would be topology and deriving output impedance. The Melquiades lorded to 12K (!!!) for instance with no feedback sounded like “chewing carton” when it drove Druids. The SS Yamaha B2 pushed probably 25 db more, forces me to plug the port and it still was hugely bloomy. It shell not be this way unless the speaker experience the SMDS – or the Severs Mass Deficiency Syndrome. So, how to deal with it?

High-passing the speaker will work but it like trashing a half of the speaker away. If you have a speaker that does >150Hz then you do not need Druids but you need ¼ cub feet box. So, how to make the Druids to work its full range (whatever it is has) but prevent the MWL to lose steam and present the LF from self-distraction?  Well, let add mass to LF with dropping output impedance of the amplifiers that drive Druids at LF. Let up to have an amp with current feedback and let to have an attenuator that would moderate output impedance let say from 5R to minis 1R. I stipulate that listening the Druids in a given room and fine-adjusting the output impedance it would be possible to catch the moment when the LF go into suicide and is not to buffer them but at list to prevent their suicide screams to point the sound of the speakers. I personally fell that it will be a very narrow margin (for instance between 1.25R and 1.3R of output impedance) that would allow very fine tuning and would make the Druids bass to be not deep but not annoying. 

So, I think the problem of the Druids bass (and other similar speakers that are made to float on mass deficiency in bass) is not the bass but the randomness of amps (output impedance) that drive them and disability of audio people to dial the output impedance very precisely (for this time of SMDS speakers).

I do not advocate to do it and to run negative feedback. Will it affect many other things – you bet, it will. However, I think that it might be a good journey to confirm that concept that adding virtual mass to LF via feedback and the fact that it will be VERY important for the speakers that suffers from SMDS.  Warn you that all written above sounds like a complete idiocy --- but I have a very high confidence that the proposed solution will work very affectively.