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Multi-Way Conventional loudspeakers with crossovers

Technics  SB-10 Crossover Questions
Technics  SB-10 Crossover Questions
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Old 7th February 2018, 09:24 AM   #11
giralfino is offline giralfino  Italy
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The idea that you can restore the original sound of an almost 40 years old speaker, or to even improve it, is foolish.
There are many parts that age, and some you can't swap with newer ones.
The electrolytic caps change value over time, so replace them with the same type. You won't improve anything with an expensive film cap in the place of an electrolytic. Apart from that I won't change anything in the crossover, film caps, resistors and coils don't age, and changing them with "better" parts without really knowing what you're doing, and without measurements, is not a good idea.
The level controls probably need to be cleaned.
Unfortunately spiders and suspensions age, and you can't change them easily. And I don't even want to think about the magnets.
I hope you paid very little for the speakers, because for the 1800 Euro I have seen frankly there are far better sounding options.

Ralf
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Old 7th February 2018, 11:14 AM   #12
TechnicsSB10fan is offline TechnicsSB10fan
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Thanks Gentlemen.
I did try to get an attenuator out today, Mooly, but I should have tried before I put the bass back in because it needed a push from the inside, so that will have to wait to next time. They appear to operate correctly no nose when turned with the music playing. I think they are a sealed unit as I have seen photos of them.

I take your point giralfino and after a week of looking at capacitor options I am not a lot wiser as to what to use. That is why I came to this forum in the hope someone else had done so experimenting with these speakers already. They really don't sound that bad, much as I always remember them being, a fairly realistic sounding speaker with out added tonality if that is the correct term, they sound much the same as the ones I got in 1981, must have been some of the better built gear of that time. Don`t worry giralfino I paid around half of 1800 Euros for them and the amp

Back to capacitors I have come across two other people on the net, one in Japan and one in France who replaced the 47uF with a large foil cap and claimed an improvement.
I think I will have to leave the two 330uF electrolytics caps as I can not see a way around the high uF value. I will just put new electrolytics in there,
I would also like to replace the polyesters that are in the signal path with something better to see if I can get a clearer sound, will longer leads be a problem? as I think they will have to be mounted out board style.
There are options that don`t seem overly expensive so I think I will start out with lower cost parts to prove if I am on the right track or not. I really need to start looking at the amp, now, I hope that is not going to be so confusing, although I suspect it might be
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Old 7th February 2018, 12:17 PM   #13
giralfino is offline giralfino  Italy
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Quote:
Back to capacitors I have come across two other people on the net, one in Japan and one in France who replaced the 47uF with a large foil cap and claimed an improvement.
After 30+ years the original electrolytic caps are surely way out of specs. So replacing the 47uF old bipolar cap with a new film type effectively restore the original capacitance. You should notice the difference as the crossover will work differently in the two cases. But inserting a new 47uF bipolar cap does the same, at a fraction of the price. If someone claims to hear a difference between a new bipolar and a film cap of the same value, I suspect this is only a psychological effect, and a double blind test will fail.
So I suggest you to replace only the electrolytic caps with some new equivalent ones. All else is IMHO a waste of money and time.
Quote:
they sound much the same as the ones I got in 1981, must have been some of the better built gear of that time.
Don't hold a breath on that, you simply can't remember the sound from 30+ years ago, and Technics wasn't a high end maker anyway.

Second hand shopping can bring big saves, but only for recent gear. Vintage is only for sentimental reasons, performance wise there is no game with good engineered recent items at the same price.

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Old 7th February 2018, 01:18 PM   #14
TechnicsSB10fan is offline TechnicsSB10fan
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Do you have a favorite make as the original ones are no longer available?
Is it the same with the amps, ie just need to replace the eletrolytics, are there other parts that may need replacing? have just been searching the part numbers and not much is coming up
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Old 7th February 2018, 01:39 PM   #15
Mooly is offline Mooly  United Kingdom
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Technics  SB-10 Crossover Questions
I would agree with most of what giralfino says regarding the caps. You could always try two 1200uF or 1500uF series caps to make a 600uF or 750uF bi-polar which are both right in the ball park.

Heat is the big killer of caps in an amp and so any that are in locations that run hot would be suspect. Age can be a problem but that said I have stuff from the mid to late 70's that is all original and in perfect working order.

If you want to change all the electrolytics in an amp then be 100% certain you know the value and orientation of each before removing them. Its easy to get confused when you have removed 30 or 40 caps and then start thinking erm, right then

If the pots on the speakers are OK and there are no 'dead' spots and so on as they are slowly rotated then just leave them be.
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Old 7th February 2018, 01:44 PM   #16
Mooly is offline Mooly  United Kingdom
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Technics  SB-10 Crossover Questions
Quote:
Originally Posted by TechnicsSB10fan View Post
Do you have a favorite make as the original ones are no longer available?
Is it the same with the amps, ie just need to replace the eletrolytics, are there other parts that may need replacing? have just been searching the part numbers and not much is coming up
My advice for what its worth would be to always go for reputable well known commercial brands and not 'boutique' offerings. Look for 105C temperature rating for new electrolytics. And always buy from recognised companies who are the authorised distributers for the brands concerned.

Semiconductors don't wear out as such... resistors are the same unless they are underrated and running hot, which is common in a lot of equipment actually. These can usually be spotted by looking for discolouration on the resistor and board.
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Old 7th February 2018, 04:05 PM   #17
eriksquires is offline eriksquires  United States
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Giralfino,

Shunt caps are often big. A cheap source of film caps that users have said made things better is Axon. It is the Solen/SCR "bargain" braind.

In series, I like to use Mundorf MKP as my bargain brand, Clarity CSA for a darker presentation.

Best,

E
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Old 8th February 2018, 02:29 AM   #18
TechnicsSB10fan is offline TechnicsSB10fan
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Hi eriksquires, Yes I have seen the Axon caps and noted they are a slightly smaller size than many of the others, might be good if space is restricted.
I haven`t made any decisions yet as what to do cap wise yet.

Today I have the amp open. I am a little concerned that is giving a smell off during use, I had changed the voltage setting to 220v instead of the 110v that it was set at it came from over the seas, maybe it is something to do with that they do run hot anyway and it is about 35C here to start with.

I am having a close visual inspection and have noticed what appears to be some leaking from the base of two large capacitors, what do you guys think?

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Old 8th February 2018, 05:53 AM   #19
picowallspeaker is offline picowallspeaker  Italy
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That's the glue for keeping 'em firmly attached !

About caps, is 47 uF the one in series with the midrange ? ( on the schematics it was 12+8=20 uF )
I'm a little bit skeptik about differences between film and electros in that position, because the magnitude of distortion introduced is so little compared to speaker's distortion.
But a film one usually is better.
I wouldn't use a polarized one ( or two in series...thou a polarized one is effectively obtained by having two in series in the same "container" ! )
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Old 8th February 2018, 06:25 AM   #20
TechnicsSB10fan is offline TechnicsSB10fan
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Good I hope so it only seems to be on one side though.

The schematic is accurate there are two polyester films in parallel 20.6uF in total
I was wondering if a 20uF film would be close enough?

The 47uF is on the the bass circuit along with a 0.47uF and two 330uF
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