SpeakerTalk

[JoeM]

I just joined and hope this post is allowed. Is this speaker too new? Sorry if I made a mistake, but I bought it new about 25 years ago and need some help.

First, I have seen suggestions that I upgrade the components in the crossover. As near as I can tell, it may be a DN12 SP 1004. Is this a good thing to do? How do I get inside to do it. Take off the LF driver, or do I have to take apart the cabinet? Is there a schematic available for it. A longshot-does anyone supply an upgrade kit for it.

Second, is there any way I can drop the lever of the HF driver a bit, say 3-6 dB? My present room is a bit bright. My Spendor SP 100s have three sets of wiring posts for tri-wiring, so it is simple to install an L-pad ahead of the tweeter input. I suppose I could do this once I got inside and to the crossover, but again a schematic would help.

Finally, a comment. My major complaint with this speaker has been the slightly muddy lower midrange-upper bass. My house has suspended wood floors. I had the same problem with my Spendors and did a lot of experimentation with various ways of interfacing the speakers to the floor; I vastly improved their sound. I found it was impportant to both drain away any residual cabinet vibrations and to avoid communicating any vibrations to the floor. I applied what I learned to the Kefs, and their sound from the lower mid-range on down is now superb. Those wheels on wood floors were very bad. So, my 25 year-old Kefs have now replaced my Spendors, as they apear to be superior in all respects. My floor interface investigations for the Kefs are continuing, and if anyone is nterested, I can report what I have learned.

Thanks in advance for any help.

Joe

[ColinR]

I'm rather worried by the reference to the Concerto crossover SP1004.
The Ref 105-2 circuit board and schematic are in the "crossovers" part of the technical section. The Cantata which also uses the SP1049 T52 can also be found there, as it has the facility to reduce the treble output, so study it's schematic. Early 105-2 crossovers have different component values, so if you a copy of one's circuit you'll have to ask either Terry or myself very nicely .
The circuit board is accessed by removing the woofer and disconnecting the leads. Remove the foam behind the woofer and unscrew the four wing nuts holding the board. The input is via 2mm spade terminals which must not be broken under any circumstances, the head is fed by a multiway connector, press the clip to release. Recapping will cost around £80 btw

[JoeM]

a great deal, but I am sorry to say that you are dealing with a bit of an electronics beginner. Thought I took a course in the subject decades ago, I remember little beyond Ohm's Law, though with heavy concentration, brwos furled, I can usually make some sense of a circuit diagram.

I just guessed at what X-over unit is in the 105.2, and I guessed wrong. Do you think I should upgrade the components, and which ones? Would this improve the sound? I would guess that the capacitors would be the first choice, and that I should use use something like modern polypropylene ones.

I am extremely interested in your comments about the possibility of tweeter level adjustments, and any help you give me with circuiut diagrams, circuit information, or whatever, would be most appreciated. I would grovel at your feet, if necessary, though it's a bit hard to do from Santa Cruz, California. Do you like wine? I could provide you with some of my expertly-made private reserve, which is far better than the usual Calif. plonk (this might have to await my next trip to UK).

All this results from my recent realization that the 105.2 is actually a much better speaker than I had thought. When I bought them around 1980, I thought they were the best I had ever heard. My only complaint was the lower midrang on down was a bit "congested." Three years ago I listened to about 75 pairs of speakers in order to make an upgrade and picked the Spendor SP 100. However, I learned that you must provide the proper support and isolation from the floor to make these work at their best, and when I had my Kefs returned from the loan to my son recently, I applied what I had learned about support to them. In short, I got rid of the wheels and provided a much better interface to the floor, and the 105.2s now clealry outperform the Spendors. The detail and clarity in the lower midrange is superb and very natural. If there is interest, I can post what I have leraned about speaker support.

Thanks in advance for any assistance!

Joe

[ColinR]

Looks like you're going to have to get some Chorales cheaply and practice upgrading them and add an aB section for the tweeter first, as a training exercise before going onto your major project.

Study the 105-2 and Cantata schematics I've already mentioned and consider replacing L6 (short in later versions) with a 12 Watt attenuating resistor of 4.7 Ohms.
The only other component likely to need replacing is the 80uF C8. Remember quality components like Solens are big sods so you have to think about the geometry and the posibilty that you may have to mount them on the circuit board side.
Sonic improvements, they'll sound a little brighter.
Remember series components affect the sound quality to a greater extent in any classical crossover design.
Now if you don't want to molest the circuit boards you could always dampen the treble response with a folded silk handkerchief, felt (baise in the U.S.), a tea towel (napkin) or some woven material not as acoustically transparent as normally required. Knitting and crochet are useful hobbies in these cases, as the techniques will cope with both silk and rope!
It doen't matter if it looks dumb, you listen with your ears not your eyes.
Wine will be fine .
Contact me directly if you require a Chemist's point of view of all this electronic smoke 'n mirrors.

[proffski]

I have always found that replacing nasty non polarised electrolytics improves the sound.
Most certainly ones that date back from the 1970/80s.
As you say the size can be mind boggling, as is the cost for the larger values.

Having just rebuilt the EHT Trays in some Quad 989s, we also changed the one and only N/P capacitor with something more deserving of the panel. At 220uF IT WAS HUGE!

Even though it had a combined resonance at just over 26kHz...

Ah, the rewards were remarkable!

Damping, I use sheet rubber or very heavy dense packing foam whenever I can get it. Always been tempted to try crossovers in a seperate box.
Any ideas anybody?

[adam_audio]

[adam_audio]

[ColinR]

[proffski]

Not only is the ESR different, so is the Q.

Next time you have access to a capacitor analyser see what happens to the value as the operating voltage varies in a non polarised capacitor.

You have a lovely FM modulator…

[JoeM]

First, being new to this Forum, I'm not sure where exactly to find what Colin refered to when he said the following: "The Ref 105-2 circuit board and schematic are in the "crossovers" part of the technical section." I looked for fair amount of time, but didn't find what I expected to find. I did drop a note to him, but I feel that probably I have bothered him enough, so I'll try bothering you all some more.

I'm still not clear whether I can expect much or any improvement upgrading the caps on the crossovers, but I suspect I will do it and find out. Modern ones can perform much better than the ones that must be in the 105.2. I hope I can read the values. I upgraded the coupling caps on my EAR 834p and did hear a real improvement. Though that is a new unit, those caps are directly and importantly in the signal path.

Adam, as for improving the performance of the lower midrange (the
B 300), it can be done. If I had known, I would have saved myself the time and cost of buying the Spendor SP 100s. What follows is not particularly scientific and the explanantion may not stand up to scientific scrutiny, but empirically it all works. For want of a better term, I call it DDI- drain, damp (or dissipate) and isolate. (I have also found that electronics are very important, but more about that later.) First, speaker cabinets vibrate, even such well-built ones as the 105.2s. You want to drain away those vibrations to something that damps or dissipates them. You also want to prevent those vibrations from reaching the floor if you have a suspended wood floor. Some people will say you have to immobilize the speakers with spikes or some such. My experience and Newton's Third Law says that it is not important at all.

I am still playing with my supports but here is where I am so far. I have removed the wheels (unthreaded them) and placed some sorbothane pads (about 1.5 inches square by 0.5 inches thick) over the screw holes. I found that Ikea happens to sell a cutting board of birch 14.5 inches square by 1.5 inches thick that makes a very nice size for the sorbothane pads to rest on. The board is slightly smaller than the speaker at the bottom and has a rubber band around the edge which serves no purpose in this application, but looks sort of nice. Under the cutting board I have four 1.5 inch round felt pads that hardware stores sell for going under furniture or lamps. This sits on my suspended wood floor. I can easily slide the speakers around on the bottom pads. The sorbothane absorbs and damps nearly all of the cabinet vibrations. The cutting board aborbs and dissapates whatever is left. There are many variations on this of course. You probably don't absolutely need the cutting board. You could go speaker-sorbothane-pad-floor. There is a platform made by the Auralex Co. called the SubDude (I'm not making this up), which is supposed to do just what I have been describing.

The result of all this is a very clear transparent bass, as good as I have ever heard on any speaker. On complex orchestral passages it is possible to hear clearly the separate lines and instruments in a very natural and convincing way- the speakers do not call attention to themselves. The entire high end also seems to improve (I noticed this with my Spendors as well), for reasons I don't understand at all; maybe it's an illusion brought on by the clearer bass. My complaint about the bass of the Spendors- the ports are really sort of a cheat- of course doen't exit with the 105.2. Now I think that the Kefs would give what I have though were the best speakers I had heard- the Sonus Faber Amati Homage- serious competiton.

When I bought my Spendors, I was warned that the big woofer put special demands on the amplifier. I was told that it worked better with SS amplification (high damping factor) and that it need lots of power and lots of current. The amp must completely control the woofer. People say lots of things in this business, some which is actually true. I tried several amps and found they did make a difference. The best I found was the Plinius 8200 integrated (now superceded), clearly performing better than my old Adcom GA 555II (much better than it), the Musical Fidelity A300, and the Musical Fidelity A3cr combo. Before I had loaned out the Kefs to my son, I had run them with the Adcom. The Plinius seems to be much better, very tightly controlling the woofer as it does on the Spendors.

Well, I've gone on for a long time! I hope this is of some help.

Regards,

Joe

[ColinR]

Check your email

[JoeM]

Colin:

These circuit diagrams are very helpful. Interestly, I had already decided if I were going to put in an attentuation resistor, I would put it right where it is in the Cantata. However. I don't think I would put in a single resistor, but make a little L-pad with two resistors so that the amp still sees the same impedance speaker. That may be unnecessary.

I've been experimenting with with various layers of thin tissue in front of the tweeter and have found a very nice level. Great tone control!

Thanks again!

Joe

PS: I did not receive any direct reply to my email. so either you have the wrong address or something went astray.

[JoeM]

Having now studied the schematic a bit, I have a few questions that perhaps someone could answer. I notice at the input there are two capacitors C1 and C3 in parallel. What are they for? It appear that they could be for removing any residual DC that could be coming from the amp. If that is the case, are they really necessary? Of course, they may play a totally different role that I just don't understand.

There are quite a few capacitors in the crossover. If I were to replace all of them with modern, high-quality ones, it could cost a fair amount. Is it worth it? Are some more important than others? What about the coils? And while I'm at it, would it be worth the effort to re-mount the crossover outside the speaker.

Thanks for any assistance.

Joe

[ColinR]

[JoeM]

C1 & C3 are normally referred to a "dump caps" in case your amplifier dumps its transistors, they also a slight hump to the bass units response. I wouldn't worry about them.
[quote]

Can they simply be eliminated? Also, can the protection circuit be eliminated? There's a dashed line around a small unitwhich I assume is part of it.

My anechoic chamber and associated lab equipment are currently udergoing major renovation, so I think I'll pass on the coils.javascript:emoticon('')

(If you sent m an email directly, I never did receive it. Wrong address?)

Joe[/quote]