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Around Again ... 105's discussed.

 
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T.O. Chef
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PostPosted: Sat Jul 18, 2015 11:05 pm    Post subject: Around Again ... 105's discussed. Reply with quote

Excuse me if this is getting a bit boring among the senior contributors who have offered so much, in so many posts here on the subject of the venerable 105's (Original version in particular).

I have just finished restoring 2 pairs of 105's.
(Both pairs have the crossovers without any Zobel on the tweeter and each sport a pair of 3.3uF cap's in series on that leg.)
The first set driven 400km's to me by owner to ensure a proper job of recapping using (primarily) Falcon supplied Alcap's.
To Audiolabtower ... this pair may be of some interest because they had been purchased by the owner in 1986 in NYC from a dealer who admitted some alterations.
They had been in studio use we suspect, as working speakers, and crossovers adjusted to accommodate some bi-amping of the woofers. Easy enough to accomplish with the way there are designed isn't it!
In this case C5 had been changed out to a 20uF Alcap 100V (from 30uF) and C6 (nominal 10uF) was swapped out to a Japan made Unicon 50V 8uF with a measured reading of 8.6uF each side.
I'm thinking this had been done to possibly lower the response of the B-110 to accommodate a lower (150Hz perhaps?) high-pass active filter on the B-300. Do the values support this hypothesis?

I restored these to as close to original as possible not knowing the original capacitor values of the said changed out ones, but the rest were matched as "like to like" as my guesswork thought proper.
It turned out well. Very well, and I fell in love with these speakers. This brought me to save a pair from a gentleman who had parted his out for parts sale on a site we won't mention.
That's another long story and a near 1000K long round trip to accomplish but Well Worth it. Unfortunately the "stripper" didn't think to make notes on what drivers matched to what crossovers. Arrrg! I had at best a 50% chance of getting it right in rebuilding but I've very satisfied with my results sonically. I guess luck was with me!

I have a big question to any who have stayed with this post to this point Smile
The LED indicator circuit has me baffled. Does anyone have a schematic for this?
I found out early in my processes that without connecting this circuit there's NO signal passed to the T52. But on completion I found that that the LED's don't seem to function though the tweeters do function perfectly. It takes some LOUD listening to confirm this. Only one of the 4 in the 2 sets does blink when when set to "listening window", but that's it.
Are they sensitive to +- polarity perhaps? I may have swapped the connections in this regard. Can anyone confirm the correct wire colours to circuit board?
Are LED' subject to burn out? Does anyone know what the voltage values of these LED's should be? I assume 1.5V is as low as it's possible to get.

I will throw out here that these 105's seem to be (to my ears) head and shoulders ahead of the 105/2's that I've twice owned.
I was never ably to get a balanced bass from the second series though others state that in response both are near identical. This is definitely Not my experience. Both pairs of original version that I have here produce perfect bass at any level .. where the 105/2's had to be cranked high to get any real LF output.... Odd, but true.

I welcome any suggestions here on the LED wiring. A schematic of the circuit would be great to have!
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audiolabtower
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PostPosted: Sat Jul 18, 2015 11:43 pm    Post subject: Reply with quote

I posted the circuit a while ago, it was repeated in this thread
http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=1702&highlight=led+circuit

Thr input wires from the speaker terminal are white+ and black -, the wires to the led are yellow and brown. Any standard red led will do, there is nothing special about the led. The circuit has no effect on the tweeter and is just in parallel with the speaker/amp terminals and is open circuit when off. Listening window needs a highish music signal to light up - manual says use white noise from an fm tuner!

Those relatively small chnages in cap values would change the crossover frequency marginally, but not enough to take down more than an octave without changing the inductor. My tweeters also did not have the zobel, I assume from the results of the computer matching originally at the factory.

I agree with you about the sound of these speakers Smile
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T.O. Chef
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PostPosted: Sun Jul 19, 2015 1:50 am    Post subject: Reply with quote

Gratitude in Abundance for this response !!!
I had not seen this prior post with schematic, though I have scoured the forum regularly and in detail for any and all info on the 105.

So polarity of the LED connection is of no relevance!?
And, there is no need for the circuit to be active for proper tweeter function???
This seems odd to me as I was testing system impedance using WT3 software with ithe circuit mistakenly left unplugged and realized zero tweeter output (realized by the readings and confirmed with music input test).
I suppose I could have had some other issue during test, not realized.

I have purchases new LEDs and have installed one already. I can't get this to give indication of functionality either ..... So I guess I've wasted a whole Canadian dollar on the 5 new ones
I will try cleaning the contacts before going further! Why I didn't think of that first I cannot make excuses for.

Truth be known, I am so enthralled with the sound and presence of these that they have been granted the privileged position of Main Speakers in the Main system. I think they are staying here for some Time to come. Rolling Eyes

I really wish I could post before and after pictures of these 2 projects. I can attest that by far they have been the most rewarding and successful restorations to date.
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T.O. Chef
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PostPosted: Sun Jul 19, 2015 1:56 am    Post subject: Reply with quote

Gratitude in Abundance for this response !!!
I had not seen this prior post with schematic, though I have scoured the forum regulary and in detail for any and all info on the 105.

So polarity of the LED connection is of no relevance!?
And, there is no need for the circuit to be active for proper tweeter function???
This seems odd to me as I was testing system impedance using WT3 software with ithe circuit mistakenly left unplugged and realized zero tweeter output (realized by the readings and confirmed with music input test).
I suppose I could have had some other issue during test, not realized.

I have purchases new LEDs and have installed one already. I can't get this to give indication of functionality either ..... So I guess I've wasted a whole Canadian dollar on the 5 new ones
I will try cleaning the contacts before going further! Why I didn't think of that first I cannot make excuses for.

Truth be known, I am so enthralled with the sound and presence of these that they have been granted the privileged position of Main Speakers in the Main system. I think they are staying here for some Time to come.
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audiolabtower
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PostPosted: Sun Jul 19, 2015 11:15 am    Post subject: Reply with quote

T.O. Chef wrote:
So polarity of the LED connection is of no relevance!?


It does matter, but in a circuit where the current is limited (like this indicator circuit) it just will not work the wrong way round with no damage done, thus trial and error is not really a big deal.
It matters more if you connect the wrong way round direct to a voltage source, where it will immediately blow and die Wink
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T.O. Chef
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PostPosted: Sun Jul 19, 2015 12:09 pm    Post subject: Reply with quote

I will double check my wiring first Rolling Eyes
It's great to have that schematic too though! Thank you for taking the time to trace it and post for us all.

As an aside .... How would you rate the befefit (if any) of replacing the nominal 360uF Big Bass electrolytic caps with poly film type?
Would the reduced ESR throw the LF-Mid balance too far off spec?
Compensated for or augumented by the resultant loss of cabinet volume perhaps!?!? LOL.
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audiolabtower
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PostPosted: Sun Jul 19, 2015 4:01 pm    Post subject: Reply with quote

Hi, years ago when had accurate test equipment at work I replaced all the electrolytics with polyester and polypropylenes, matched to the original median values to better than 0.1%. The mid treble was then too forward which could be compensated by +2dB on the bass and -2dB on the treble if you had tone controls. When I mounted the crossovers externally I put a set-on-test tag board in series and decided on 1 ohm in series with both B110 and T52 (20W and 10W respectively), although the values may also depend on how the bass interacts and projects with your room. I did replace the 360uF with parallel 32uFs but decided against series resistor with the B300 (although in later designs, eg Kef Cresta 10 they do have 1.5ohm in series with the bass unit, although a very small driver in a small box so not really comparable in bass reach or slam etc).
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T.O. Chef
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PostPosted: Sun Jul 19, 2015 7:37 pm    Post subject: Reply with quote

Quite a mountain of cap there!
Was there a sale? Surprised
I like the idea of getting the crossovers out of the cabs and closer to the amp(s), especially the bass PCB's. As you've mentioned it makes for a lot of cable to the speakers though. The 105's are well suited to the process aren't they!?
Did you ever go active? I know there was some long discussion about it here. I have dabbled with it (not with 105's but others) and gave up overcome with challenges of space, matching amps, and wires all over the place. I was simply using an off the shelf Behringer crossover and results were not bad. It needed to be left on 24/7 to prevent accidental power up after amp's were turned on. Big Mistake that!

In my restorations with the 105's on both cases I slipped in some low value poly cap's in parallel with Alcaps to get my sum target values. I can't be sure if made a sonic difference but it obiously didn't hurt. To my ears it did not result in any "too forward" mids or bright tweeters.
I'll try to get some photo's up, not sure if I can copy and paste into the text here. If not would Allan assist if I ask nicely? Maybe?
Laughing
Still no luck with getting LEDs glowing. Maybe I Cooked them or maybe there's R problems on the PCB.
Stay tuned.
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audiolabtower
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PostPosted: Sun Jul 19, 2015 10:02 pm    Post subject: Reply with quote

Actually the caps did not cost me anything. I worked on the design of the first electronic control system for direct injection diesel engines in the 90s. The injectors needed 90V dc to work fast enough so we needed a charge pump circuit to get that from the 24V battery on a big truck. Thus I was swimming in those big caps once volume production started and could select measured values to my heart's content.

Yes I actually built the active circuit on veroboard but a previous power amp then failed dc rail before I built a suitable power supply for them, they finally ended up in the bin when I moved house. The only thing that saved my irreplaceable moded 105s from a high current 50V dc was the series caps to each drive unit. I decided the ultra close tolerance linkwitz passives were good enough if next to a stack of new audiolab powers with virtually no input speaker cable and quad wired back to the enclosures. Malcolm Hawksford at the University of Essex had done a lot of work on bi-wiring and reckoned the run at the output of the crossover to drive unit was far less tolerant of cable quality than the input side providing the resistance was low enough, and multiple amping in this fashion gave most of the advantages of true active operation anyway if the passive crossovers were good enough.

It is a mystery to me why so many so called "audiophiles" resist active speakers when they solve so many problems and insist on spending large amounts of money "tuning" systems with different amps and cables while saying tone controls are beyond the pale in destroying quality. Getting rid of speaker cable and having an amp which may not need a 1 ohm output capability since accurately matched to its known simpler load is so much more preferable.

But then most hi-fi is now a shrinking insignificant fashion industry with little regard for either physics or proven facts. Smile
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T.O. Chef
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PostPosted: Mon Jul 20, 2015 1:42 am    Post subject: Reply with quote

" It is a mystery to me why so many so called "audiophiles" resist active speakers when they solve so many problems and insist on spending large amounts of money "tuning" systems with different amps and cables while saying tone controls are beyond the pale in destroying quality. Getting rid of speaker cable and having an amp which may not need a 1 ohm output capability since accurately matched to its known simpler load is so much more preferable. "


Well Said!
I have heard active speakers and often wondered the same ... Why aren't there more of them??? But most of those were expensive monitors designed for studio use. Good, but often so flat as to be boring. Not at all engaging.

But in my world I live with the evil dragon of passive sytems.
I'm a purist at heart, and whenever I embark on a restoration process (I have many behind me now) my first goal is to bring things back as close as possible to originality.
Sometimes it's tough! I have a pair of Cantata's in the stable that I have struggled with. I just cannot seem to "get them right", in spite of the Falcon supplied cap's to published spec.
The drivers all test well and match closely in ts parameter, the cabinets are near mint including the stuffing and interior wall damping, but for some reason they disappoint sonically.
Recently I tried listening again in the same system set up but using a Yamaha C70 as the preamp. ( I usually prefar listening in passive pre-amp mode.) With a bit of experimentation using that Yamaha's parametric EQ I was amazed at how close I could get these to what I would expect from a Cantata. They were perfect in fact!
Eventually I will go back to the drawing board on the crossovers in these and make them right. But I Sure wish I knew what you know in crossover design!!!

Ahhh......It's a Wonderful Hobby!
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audiolabtower
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PostPosted: Mon Jul 20, 2015 11:51 am    Post subject: Reply with quote

Many years ago a colleague had HUGE triangular Tannoys (probably Yorks, maybe GRFs) in the corner of his listening room. When he came round to listen to my Spendors he could not believe the vocal projection, lack of fatigue and tangible image of the recording space. Converted to the"BBC" sound, he sold the Tannoys and bought a Cantata kit since expert with woodworking and made some heavy cabinets. He was very pleased with them.

If everything is working properly the only thing I can suggest is placement since floor standers can be very particular in getting the bass projection in tune with the room in proportion to mid/treble "airiness". The 105s solve the top end problem by the low diffraction effect "head" inspired by the LS3/5a experience, but he bass cabs still need care with placement to room boundaries which can make a big difference to the bass detail and reach and spoil the rest of the response upwards in frequency.
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T.O. Chef
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PostPosted: Tue Jul 21, 2015 10:03 pm    Post subject: Reply with quote

Well ..... Thanks to you Audiolabtower I guess we can close this thread (assuming there's no other interest). Though it has been very informative, interesting, and helpful to me.

I sorted out the 105 LED issues, it was indeed simply a wiring errror.
However, in the process I replaced the LEDs since I picked up 5 @ 20 cents apiece and felt I needed to justify my princely expense Shocked The new ones are brighter, identical in size and shape and made in China of course. Brighter, so now when set to indicate possible clipping they can't be missed Very Happy

I will close by saying that anyone down the road questioning whether to spring for a pair of these classics ..... Stop Thinking and Just Do It. Properly refurbished (and it's not overly difficult) they really do stand their own against anything modern. In my home the Real Resident Expert (we'll call her Ms. Golden Ears) has even capitulated in agreeance. And that's the crucial "proof in the pudding".
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audiolabtower
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PostPosted: Wed Jul 22, 2015 11:32 am    Post subject: Reply with quote

You're welcome, good it's sorted!
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PostPosted: Thu Jan 21, 2016 1:35 am    Post subject: Reply with quote

As a follow up to this wonderful exchange I'd like to add one more note regarding system selection in our wee house.
At first my wife was very happy with our recently refurbished passive 105's. She had to admit that nothing brought home to date compared to their 2 channel presentation.
But ... in the main room here the audio system does double duty. Both 2 channel music listening and 5 channel (no sub's) HT for TV and film is required. It's a bit of a complicated set-up, but it does work out quite well.

Prior to the 105's arriving the main Left & Right channels were handled by some IMF tls80's. It wasn't long before we severely missed the slam and impact of the big B-139 endowed IMF's for HT use. The trade off is relatively small as the room is small .... but the 105's have had to take up residence in the room below. Wife's Orders Smile
Unfortunately, as good as they are, the 105's simply cannot do the same thing in that HT role and there' no room in real-estate or budget to supplement with sub Woofers.
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PostPosted: Fri Jan 22, 2016 11:57 am    Post subject: Reply with quote

That is the strange thing about bass - the room. In my previous house the 105s pointed down a long room about 14 ft wide and 24 ft long. The organ pedal note on my recording of Saint Saens 3rd symphony (Montreal Dutoit) was literally felt and not heard, it was extremely impressive. Now they are in a much larger room 20 ft by 24 ft and have to project along the 20 ft dimension. Do you get the same pedal note? no, although this is the only (organ) recording where I can notice a difference. Everything else is superior, the extra space allowing slightly higher impact with rock solid imaging and wonderful depth etc, the speakers can really breath. But that 32 Hz that was there is not as powerful as before.
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