Wanna Tweak My Existing Speakers, Help...DIY Season

Autor

Beitrag

abhi.pani
Inventar

#1 erstellt: 05. Sep 2005, 15:44

Hi Buddies....
Guys after thinking a lot I have decided that I am not going to take up any wholesome DIY project however economical and VFM it might be....

But to satisfy my DIY urge as well as do something good to my system I wanna tweak my exsisting speakers....Its a pair of Sonodyne speaker, about 12 years old....

Here is the existing configuration:

Its bigger than regular bookshelf speakers but not a floorstander
Size: 60 x 24 x 30 (H x w x D) all in cms.

Its a 2 way with one 8" woofer (paper cone) and a 2" paper cone tweeter.
The cabinet is made up of 3/4" Plywood (I suppose it is a ply).
There are no internal bracings or Glasswool dampenings.
There is just one crossover inside connected to the two drivers.
Its a front ported one.

Its rated at 50 Watts RMS per channel at 8 ohms.

About the sound.....the bass is of no high quality but has some depth and can be lived with. With proper placement its infact decent (for the price).
The mids are just ok, depends on the amp, but nevertheless good one from a 8" inch driver.

The big letdown is the highs....initially it was quite good but few years back I had to replace the original voice coil and the paper cone...after that its all gone. It hardly goes to 8khz and that too the sound is too feeble as compared to the Mid/Bass driver.

Here are my plans,
I plan to invest not more than Rs.1500 on this tweak.
I want to replace the exsisting paper cone tweeter with a Dome Tweeter or if you have any better suggestions then you are most welcome.
Also I want to introduce some dampening inside the rather undamped Cabinet.
Use of Glasswool, Sand etc....whatever would be possible please suggest.
Since the inner cabinet is accessible only through the front baffles, the feasibility of applying the damping material also looks critical to me..

Let me know if I am missing anything here, If any other tweaks seems feasible then do tell me.

I am going to use this speaker in future for surrounds so I seriously mean to tweak it to its best (only tweak no remaking please).

sbfx
Stammgast

#2 erstellt: 05. Sep 2005, 21:26

Hi!,

One cant change drivers at will to anything one pleases, you have to match each component in spec with the crossover section of the speaker.

As for dampening I think it is a good idea it would help greatly.

Regards,

Satyam.

SUB_BOSS
Gesperrt

#3 erstellt: 06. Sep 2005, 06:18

Dear Abhi,

You can make away with some internal cable changes, good damping material ( take care not to stuff em too much), but I see no postive changes in replacing drivers..it might get better or worse, but since it's DIy someone has to fall into the pit, experiment with combinations and let us know..so good luck

Manek
Inventar

#4 erstellt: 06. Sep 2005, 08:23

I would suggest if you want to replace the tweeter with a dome ...go in for a fabric dome with a low "fs" of around 1khz to be safe. What order is the crossover ? I would expect the tweeter to be on a single capacitor and the woofer on an inductor....I maybe wrong.

This is definately a shot in the dark...may work out for you or may not work out for you. You could find out the nominal impedance of both drivers from the back of the driver...go to a crossover calculator website experiment with frequencies to try and find out the approximate frequency the tweeter has been crossed over by comparing the values on your crossover board and then try and implement the dome.

Stuffing would be the easiest tweak, next some cabinet bracing and maybe internal wiring.

Manek.

abhi.pani
Inventar

#5 erstellt: 06. Sep 2005, 09:26

Keep it coming guys.....

Today I will take a closer look at the crossover.
I have seen there are inductors but have to check out capacitors.
Here are my questions:

Manek schrieb:

I would suggest if you want to replace the tweeter with a dome ...go in for a fabric dome with a low "fs" of around 1khz to be safe. What order is the crossover ? .

1. Now how do I find out what order crossover it is ??
2. What is the impact of this (order of crossover) on driver selection ? How important is it to know this.
3. Manek, what is low "fs" btw ?

Manek schrieb:

You could find out the nominal impedance of both drivers from the back of the driver...go to a crossover calculator website experiment with frequencies to try and find out the approximate frequency the tweeter has been crossed over by comparing the values on your crossover board and then try and implement the dome.

Stuffing would be the easiest tweak, next some cabinet bracing and maybe internal wiring.

Manek.

4. I understand how to find the nominal impedance of individual drivers (a multimeter should help I suppose) but what are the parameters that a crossover calculator would give me to select the appropriate drivers ?

5. Is there a difference between Fabric dome and Silk dome tweeters ?

6. What brands would be available locally (within my budget) to select from ?
7. Which wires should I go for internal wiring ?

Hey Mohan,
I think there would be a definite improvement on SQ with this driver replacement job because my current HF driver is as good as non existent (it happened after I had to replace the voice coil and paper cone with a local one few years back) so I think a proper selection of hf drivers can do a lot.

[Beitrag von abhi.pani am 06. Sep 2005, 09:27 bearbeitet]

SUB_BOSS
Gesperrt

#6 erstellt: 06. Sep 2005, 10:10

I think Sonodyne uses peerless drivers so it's easy to procure them..

abhi.pani
Inventar

#7 erstellt: 06. Sep 2005, 11:36

Its 12 years old....do you still think they have used peerless ?

Manek
Inventar

#8 erstellt: 06. Sep 2005, 14:10

abhi...

try writing to sonodyne and see if they can give you any details about this peaker model in terms of crrossovers, and drivers used.

You could always start with the stuffing and bracing.

SUB_BOSS
Gesperrt

#9 erstellt: 06. Sep 2005, 14:25

Dear Manek,

Sonodyne people are too smart..when I enquired about some spares the person on the other side tried convincing that what I own is outdated and instead try newer models...so Abhi shouldnot be surprised if they convince him to pick up a Sonus 2605 instead of revealing the details he requires..very sad, but nonetheless he can always try..

abhi.pani
Inventar

#10 erstellt: 06. Sep 2005, 14:55

ya...even I havent heard anyone getting such kind of services from Sonodyne....they just tend to forget their previous models and carry on with their new models..

abhi.pani
Inventar

#11 erstellt: 09. Sep 2005, 10:04

Manek,
You are almost right, I checked out the crossover inside the speakers, it has 2 inductors, one capacitor and a resistor.
I think I will require a mutimeter to measure their values.

How do I match the fs btw ??

Manek
Inventar

#12 erstellt: 09. Sep 2005, 10:18

so my guess it that the one inductor and cap would be for the tweeter and the other inductor for the woofer or it could be the other way round.

The resistor would be used to pad the tweeter.

You will need an lcr meter to check the inductor, cap and resistor(not if you know how to read resistor colour codes) values.

You cant match the fs as you dont know the fs of the current tweeter. What is the nominal impedance marked on the back of the tweeter ? six ohms or 8 ohms ? whilst you are at the lcr meter also measure the DCR of the tweeter.

Do remember this exercise of tweeter replacement is a shot in the dark so you neeed to get a tweeter similar in certian basic parameters and cover for headroom. Do also remeber that it may or may not sound as you think it would so be prepared to loose some money if it does not turn out right....

Forewarned is forearmed.....

Manek.

Manek.

abhi.pani
Inventar

#13 erstellt: 09. Sep 2005, 10:43

Manek schrieb:

The drivers dont have any specifications written on it.
But I think I can measure the resistance across it using the icr meter...

Is there a way to know as to at what is the xover frequency for the tweeter ??
btw the speakers just have a rating of 55hz - 20khz and 100 watts pmpo....its around 30 watts rms
So I suppose the tweeter should be selected below 50w rms.

Manek
Inventar

#14 erstellt: 09. Sep 2005, 11:24

not necessarily....only below 50w.
But please try and make this tweak as cheap as possible as you will not able to extract much performance from those boxes.

Manek.

abhi.pani
Inventar

#15 erstellt: 09. Sep 2005, 11:30

Manek schrieb:

But please try and make this tweak as cheap as possible as you will not able to extract much performance from those boxes.

Manek.

Yes Manek, Even I have similar plans...my budget is around 1200 bucks including stuffing, internal wiring and tweeter replacement. Now can you people suggest some brands of tweeters that are economical, giving decent performance and available locally ?? That will be of great help.

SUB_BOSS
Gesperrt

#16 erstellt: 15. Sep 2005, 12:00

Abhi you can try Philps tweeters if they are available

Manek
Inventar

#17 erstellt: 15. Sep 2005, 12:04

or maybe if you can source some peerless india tweeters...

manek.

abhi.pani
Inventar

#18 erstellt: 15. Sep 2005, 14:11

Thanks guys...I was also thinking of Philips but peerless seems to be a better option. Any idea where I can get these (either of them). Will it be available in S.P Road here ?

SUB_BOSS
Gesperrt

#19 erstellt: 15. Sep 2005, 14:35

philps are available with authorised service centres

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