guy sergeant wrote:

Hi Romy, My experiences with the SL6 and SL600 date back 15-20 years. My problems with the sound I could get from them related to their inability to recreate music with scale or drama. I found the subjective lack of high frequency output made every recording sound as though it was made in a room lined with thick carpet. I didn't think they were at all good at reproducing the timbre of piano or strings. I can't give specific musical examples, it was too long ago. Their low sensitivity meant that very powerful amplifiers were required. These amplifiers were generally compromised by their inherent complexity and they generally sonded poor on other more sensitive loudspeakers. The best results were probably achieved with a friends home made very large 100 watt Class A transistor amplifier which at least got hold of them a little. While you could hear the benefits of the aerolam box (particularly when comparing the speakers to the wood boxed SL6) the overall feeling was that you were fighting against nature. In a way I felt the same about the contemporary Apogee loudspeakers. Although the sound of these was very different, the type of electronics required again made them uninteresting. I take it that you are enjoying the Celestions. They did get many positive reviews in their time. I never managed to get them to make music sound interesting and even at that time far preferred the results I could get with lower powered valve amplifiers and more sensitive speakers. What do you find to like? Perhaps you should also look out for the peculiar 'beachball' subwoofer they manufactured to augment the bass output.

The Cat

guy sergeant wrote:

What you say may be true. I'm not sure there was an amplifier available in the mid to late 1980's that would have been suitable for these. They did get good reviews but I suspect that some of this was due to awe inspired by the technical achievement of making the cabinet and the laser interferometry images. It was almost as though some reviewers were afraid to criticise them. Presumably they found amplifiers that they felt were suitable. I seem to recall Krell amps being used but I didn't like those either with the Celestions (KSA50 or KSA100) or with any other speakers.      Ah I understand now.... I was probably just using the wrong speakers!!! If there was a suitable amp then, I certainly didn't find it. It did make me question the wisdom of making such a thing (clever cabinet or not) if there wasn't an amp that could make it work.  I'm not even sure a suitable (commercially made) amp exists now. Even if you could make or have made an amp to squeeze some life from them I'm sure that amp would sound much better on more sensitive speakers anyway. I always preferred Peter Snell's original Type K design which was a smallish two way IB with relatively low cost Vifa drivers but which gave far more life and colour to music than I could ever imagine the Celestions producing. I look forward to hearing of your further adventures with them and must admit that if I found a pair I'd enjoy putting a Revelator tweeter in and trying to find a 6" driver I liked. I imagine, given what you said earlier, you'd be trying to reduce the LF bandwidth but this may be throwing away the benefit of the cabinet design. I don't know.

The SL600 obviously should not be used all the way down as those PVC woofer begin to pump air intend of sound. I crossing them (electrolytic with active bias) at +15Hz-60Hz form their natural decay. The Lover sound transferred into my LF line arrays at 60Hz. I was driving them with 5 amps, SS and tubes, including the new full-range Melquiades (in small room it has enough powers to develop good volume as I driving the 6C33C there at whole 60W) All amp made the SL600++ sound like crap: no dynamics, very challenged, very small, diminutive and with all other negative sort of things. Then I brought Lamm M1.1 and it did all necessary things.

I still not there yet as the key is in the very precise cutting off the SL600. I would need to inhale them at the very strange location were they will be living in my room and perhaps then try to optimize them. I will be doing it in a few weeks AFTER I resolve my interest in “fundamentals channel” as I am planning to settled the SL600 on the frame of the “fundamentals chancel” support.

Rgs,
The caT

guy sergeant wrote:

I suppose the question then is, does the SL600 then sound more correct than your normal system with 'better' amplifiers? Don't you still find the sound of the woofer to be too smeared, slow and dark?

Actually they are phenomenally balanced and integrated between the drivers and drivers to enclosure. I did not detect any sound of the woofers at all if I do not overdrive them. As soon I stress them ether with power or with LF frequency extension then they do fall apart. But why does one would go into stressing them with amplitude or with bass? The objectives are very different: do not let them play any stressing bass as all.

guy sergeant wrote:

There must also be some substantial attenuation (20 dB) being applied prior to your bass system to match its output to the Celestions. Isn't the effect of that audible?

Nope, the LF section that use for the SL600 is 88dB and I put the LF on a transition slope.

guy sergeant wrote:

Isn't the character of what the Celestions produce also radically different to that of your bass system?

Hm, it is still to be seen and as it should be properly integrated: something that I did not do yet. It possible that better woofers might be found but between two drivers that I tried I did not find success, including the Utopia drivers that I mentioned above. In fact, I did not think as now that the SL600 have problematic woofers: I believe that they were severally overdriven in the original design.

The Cat

After spending two weeks with high-passed Celestion SL-600 reinforced with external LF section I would like to make some observations. I had a single SL-600 monitor (I always tend to use one for assessment purpose) on it’s original stands in the very middle of my room. The monitor was reinforced with a pair of LF line array on right and left. The monitor and the LF sections were more or less OK integrated (not perfect but survivable), set to be in phase with Celestion woofers. I did not do any measurements as I did not practically cared. The sound was generally very acceptable. Was it be the same as I was getting from the full-scale Macondo Acoustic System? Absolutely not! Macondo has very different presentation and deliver very different drama of presentation. However, the SL600  + all my additions did very good from a perspective of ordinary Hi-Fi. Do you remember how 50K-70K loudspeakers sounded in the rooms of your dealer or at your favorite room of any recent high-end show? The SL600 did more interesting in my room – more “accurate” and with no major sonic “mistakes”. It was perhaps to enough to say that it was as good as I expected but quite reasonable and acceptable for a second system. I have to tell you that I did not mean to put it as “ultimate monitor” as I have a well performing loudspeakers and I do not need two systems. However, the SL600++ might bean excellent low-maintenance “summer speakers” or the speakers that I can run while I am working (that is actually more complicated).

So, I was quite happy with result and I decided to put them at the location where I meant them to sit: to strap them to “fundamental channel” stand. The sunny part that in there the Celestion SL-600 turned into an absolutely unspeakable crap. I can’t believe how bad it was!!! I made some further experiments with them and surmised that they are phenomenally sensitive to everything. The listening distance is very important. If they sit a little too far then I have no HF, if they sit too close then I need to cross them very high, almost at 150Hz. If the SL-600 sit at the location where lower and upper boundary are too close (too tall stands) then the SL600’s woofer couldn’t be crossed at all and can run full range: it sounds very clan and with no distortions at all. However in this case the HF driver dose something astonishing. It begins to sound like you scratch a frying pen with knife with distortions that probably might be over 80%.  I never heard in my life: the “fundamental channel” stand could be moved up and down with a second and the sound of the SL600++ changes from very clean and accurate to absolutely faulty just my moving the speaker with 2 feet vertically.

Rgs,
Romy the Cat

Well, it took almost two month and much more money then I thought but I was eventually able to get very decent sound out of monitors.  The SL600 sitting on my “fundamental channel’s” tripods did not do well as I told before and I was forced to sit them in their original stands. Also, I have concluded that one of SL600 tweeters was defective. It worked fine but it did not sound as good as it did initially. Presumably it went down while was playing in my room. The bad part that I was buying the tweeter 3 times as the few that I have bought did not sound as good as I expected. Took some money to do so, well, “C'est la vie” … Anyhow, all my experiments with better MF driver and tweeter did not succeeded and I end up with driving SL600 as they are, with a moderate high-pass at 70hz. Of course a separate dedicated LF sealed Scan-Speak section compliments the SL600 under the bottom from 100Hz and down.

Wow, what an interesting sound! Different but very interesting! Also, what is wonderful job the Lamm M1.1 does on the SL600. I still would like to have the M1.1 to be slightly less granular and less abrasive but it would take a different amplifier. Still, the M1.1 inhale very interesting sound into the SL600. Surprise, surprise it have very unexpected dynamic sound, despite of its 88dB misery and do not fall apart easily with complex music. I was playing on my new monitor setup the Shostakovich’s 8th Symphony, properly performed and mastered. What an interesting things. The their movement should be Mahler-like effective and cinematographic however it should be also in the Shostakovich unique style be trite and vulgar. Most of audio do it effectively pornographic, stripping that sense of self-duplicated disdain. The M1.1 with SL600 did it right as it should be: a perfect salsaof the dual baby-tornados from movie “Twister” dipped into Russian hair-down self-Moronity and Soviet dancers of comedians…

The only thing is that I feel that I will burn them quite fast. After Macondo, that I generally listen quite loud (because I can) I have tendency to drive the SL600 relatively too hard. Well, if they will not live for long then they will have a good short live (I got a couple of SL6 for parts). I wonder if any cold running, AB, good sounding SS amps out there to make my “summer during global warming” setup?

The caT

Chirag wrote:

My Tannoy 10" sealed box (not tannoys cheap boxes) ….

As I’m learning you was quite wrong in this. Can you tell me more bout the box for your Reds and why fill feel the Tannoy’s original box did not satisfy you?

Chirag,

May ask you: how you drive your Reds 10” and the most important do you feel any their deficiency in power handling. I mean after the 109dB Macondo I have tendency to drive the small Reds slightly hard and this LF drive do not really handle full stress well. I wonder if it Milq is choking on Reds or the 10” reds are fairly fragile.

Romy the Cat wrote:

May ask you: how you drive your Reds 10” and the most important do you feel any their deficiency in power handling. I mean after the 109dB Macondo I have tendency to drive the small Reds slightly hard and this LF drive do not really handle full stress well. I wonder if it Milq is choking on Reds or the 10” reds are fairly fragile. The Cat

Chirag wrote:

You have no idea how masochistic some of the amplifier issues have been with these little speakers.  I know exactly what you mean about power handling deficiencies AND would add dynamic inabilities.  I do think tonality and dynamics can be functions of one another and this is the major reason these undynamic little reds are ultimate dead ends...but they can work in limited capacity for current needs.  The golds and DMT's work better with stress, but cannot hold their own tonally.

The dynamics is an extra subject. The HF driver does surprisingly OK in terms of dynamic. The LF driver is another story. The Reds in a right “untreated” box do their typical “primary resonance spreading” and it certainly do not give an impression of dynamics in the terms as we use to…

BTW, it is interesting that you find the Golds and DMT's tonally challenged compare to Reds. Can you elaborate on it? The Golds need >150W to drive them….

Romy the Cat wrote:

I used my typical “flash” techniques and discovered some leeks in that 50 years old enclosure. Sure it the leaks were there then it would be no “acoustic suspensions” and the driver would run further. So, fixed the box with the liquid wood and the problem with the Red’s “sinking” is gone.

Romy the Cat wrote:

The dynamics is an extra subject. The HF driver does surprisingly OK in terms of dynamic. The LF driver is another story. The Reds in a right “untreated” box do their typical “primary resonance spreading” and it certainly do not give an impression of dynamics in the terms as we use to…

Romy the Cat wrote:

BTW, it is interesting that you find the Golds and DMT's tonally challenged compare to Reds. Can you elaborate on it? The Golds need >150W to drive them….

samuel33 wrote:

Can you explain Roomy your points ? Because you say all the time what should be an intresting path but you never tell why. Why high efficiency mid driver would be an improvement? why higher effeciency would increase the sound quality? Can you develop, because reading you saying X or Z is great without developing is quite boring. Are you here to develop ideas ? you never finish what you start to say....you just throw couple of ideas and after you make a post on another subject and again and again... I have a deep feeling of emptiness after reading your statements : even a 14 years old pupils have a more constructed way of arguing than you. Sorry but it'is so annoying ... at first i thought that you create your website to share, ok your very funny when you criticize other manufacturer but there is a deep lack of consistency.on the other side...and i regret it. Which concept of electrodynamic speaker have you in mind ?

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.

I use the SL-600 as my summer monitor, driving it with 100W A/B amp and I do like it all around balance, size and many other factors.  The SL-600 has beautiful cupper tweeters, phenomenal in my view but the circumstances of my habits made me to look somewhere else. The SL-600 has second-order 12dB/octave slope at 2.3kHz but…. the SL-600 has sensitive in low 80s and I'm keep destroying those tweeters. I have burned 6 of them. Not truly burned but afar a few months/weeks/days of use I hear that the tweeters got changed and do not sound as good as initially. I understand that my barbaric Macondo-spoiled habits with high dynamic range are to blame and I do admit that I drive the SL-600 much harder that I shell. But it is what it is and I am not willing to moderate my listening habits.

Here is the question. The SL-600 is old speaker and many people might went over the same dilemma. So, is any tweeter out there that would work well with SL-600, would not require a lot of modification and would tolerate abuse well? I am not intend to make long experiments and rather am looking for a plug-and-play solution. I am sure somebody out there, and most likely the Brits, have already off a shelf solution.

manisandher wrote:

Hi all, This thread has been a facinating read for me, and has prompted me to resurrect my old Celestion SL600 speakers. But their copper dome tweeters are looking (and sounding) rather worse for wear. Does anyone know where I could source them from? Any help you could provide would be really appreciated. Mani.

Thanks for the advice Romy.

But actually, I may not need new tweeters after all (for the time being, at least, until the dreaded 'Autumn Sound' arrives).

You see, when I connected them up, I didn't really think too carefully about the speaker wires I used and connected them to the amp (an old Plinius 8150 integrated I had knocking around) with 'bell wire' - the only stuff I had lying around at the time. Not surprisingly, they sounded awful.

But having replaced the 'bell wire' with thicker cable (just cheap multi-stranded copper stuff), they sound much more believable.

I take your point about the quality of the amp driving them. I think the Plinius is a pretty good amp. The only other one I have stored away is an old Pass Aleph 4. I might try this one at some point and let you know how I go.

What were your experiences with SL600/cable combinations -any insights you could share?

On a slightly different note, I was talking to a 'high-end' dealer over the phone about a certain pre/power amp combo (retailing for around £10K here in the UK). When I mentioned that I was looking to use it to drive my old SL600 speakers, I could hear the 'disgust' in his voice. He was adamant that I would need a pair of speakers substantially 'better' than the SL600s, costing at least £7K, to match this pre/power combo. To his credit, he did say to bring the SL600s in and compare them to a £7K pair he stocks. And I probably will. But unless they're IB with 1st order XOs, I doubt I'll be satisfied.

Any thoughts on why dealers think a pair of speakers should cost the same as an amplifier in order to be a good match?

Mani.

Romy the Cat wrote:

They need a LOT of very good power, preferably in class A to sound the best and then will not last long with a lot of power. The caT