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PostPosted: 03 Jul 2018, 04:39 
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Joined: 02 Jul 2018, 04:11
Posts: 5
Location: Ghent Belgium
Hi All,

First come back on this friendly forum since 2015. I had been helped very nicely by your fellow member "system7" (Steve in Portsmouth) in my project to refurbish a pair of old Wharfedale Linton 3XP.
Just started a new project, trying to get my first decent (in those times) speakers Wharfedale Super Linton W30D from 1969 back into operation.
They are still in nice condition (walnut veneer is beautiful), but I have a few questions.

1. They are listed as impedance 4-8 ohms, which means +/- 6 ohms: right? My main amp is a Marantz SR 430 2x35W, impedance 4-8 ohms: is it compatible?

2. Is it possible to change an impedance rate on a speaker? Change caps or resistor? (sorry, I'm quite good for mechanics but my electronic capacities are a bit limited…)

3. I replaced the rare and fragile original "jelly fish" tweeters (one was fried anyway) by a pair of Peerless: sounds quite nice. Kept the heavy aluminium framed, big square magnet woofers. Also fitted two more bolts to secure the woofers into the box (there were only two…)

4. Damped the inside of the boxes with special damping foam for audio, and kept the original rockwool: is that too much, they sound a little muddy now.

5. Should I change the caps (Elcap 8ufd 50V) for new or different ones? and would it make a noticeable difference?

Many thanks in advance for your help and advice.
Cheers,

Hugh.


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PostPosted: 03 Jul 2018, 16:41 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, Good show on refurbishing vintage gear and not just trashing it like many folks might. First I would not worry about the impedance. The speakers and amp are similar and ought to work together fine. The second part is a bit trickier. If the sound is now muddy and it is not because the woofers are in need of reconing then I would guess you have over damped the enclosures. Remove the stuffing and see if it changes. If not then the foam is a likely cause. If it is removable then do so and see what happens. Try both ways with the stuffing in or out. Another possible issue is to verify that the crossovers are correctly connected.

Good listening
Bruce

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PostPosted: 06 Jul 2018, 05:07 
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Joined: 02 Jul 2018, 04:11
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Location: Ghent Belgium
Hi Bruce,

Thanks a bunch for your quick answer. I cannot bear trashing things unless I'm sure they're absolutely unrepairable.
My main DIY activity is refurbishing old vinyl turntables (the mechanical changers like Dual's, Lenco's etc.): a lot of mechanics and no or very few electronics. That's my cup of tea. Unfortunately these old jewels also need an amp and speakers to work, and there, my skills are limited to soldering and replacing switches.

Re: impedance, I measured the drivers with multimeters, both analog and (cheap) electronic and I get respectively 5 Ohms (analog) and 7,7 Ohms (electr.). On the other hand, I discovered that my Peerless tweeters are (faintly) marked 4 Ohms. Wonder If I do not need higher impedance on the tweeters. Is there a way to correct in any way by means of resistor or cap on the crossover board?

Tried to replace the original 1969 8 ufd 50V Elcap's by more modern Monacor caps ( MKP 8.2 uf 5% 250VDC), but it seems to sound even worse…
Will try the Elcap's again.
Will also try the removal of the stuffing as you suggested and re-try the original setting.

I'll not fail to let you know the results of my "tweakings".
Thanks again,

Cheers,

Hugh.


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PostPosted: 06 Jul 2018, 09:00 
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Location: Arizona, USA
Hi Hugh, I believe I have seen you on the vinylengine forums. I too work on older TTs. There are 6 here now. A custom one based on a Dual 701 drive assembly, a Sota, and Emipire 598, A Pro-ject, a Philips 212, and a Transcriptor Saturn. 5 of them are on line in one or the other of my two main systems.

Unfortunately a meter that measures resistance will not be accurate when measuring speaker impedance. The actual impedance has inductance involved as well. Resistance can give you a sense of what you have, but won't tell the whole story. Worse...because of the inductance involved the impedance will vary with frequency. Usually there is a peak some where and it can be many times the average level. So...

There are a number of computer programs around (I use the one that comes with LDC-7) that will work regardless of the mismatch of impedances between woofers, mids and tweeters. I suspect a search will come up with some. If you can't fine a suitable program PM me. The biggest problem I see is that you may not be able to find the data needed to do the computations.

Since there are a lot of friendly folks out there someone on this forum or perhaps the diyaudio.com one would have better answers. For a long while there was one on Parts Express but I am unsure if it is still active and how much help it would be as they liked to work with drivers they sold.

I have not used either the Elcaps or Monacors. Changing caps can mess stuff up. My current favorite for cost vs performance (this month) is the Audyn Caps+. Very inexpensive and nice sounding. Their TrueCopperCaps are even better, just about 6 times the price.

Let us know what you discover.

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PostPosted: 09 Jul 2018, 04:30 
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Location: Ghent Belgium
Hi Bruce,

Thanks for your detailed answer.
I suppose I can use the original crossovers present on the speakers.
They only feature two coils and a 8 uF cap plus two resistors (one 3.3 Ohms and one small one labeled 6R8 5%).
Will leave the resistors alone.
Is the difference between 8 and 8.2 uF (the original and the replacement caps available) of any importance in the output of the tweeters? 8 sounds better/louder than 8.2 (?) Sorry to ask silly questions but I'd like to understand what it's all about!
This really is completely different than a 1219 Dual or a TD 146!
Will attempt today to re-fit the old caps and try them again.
Have a nic day,

Cheers,

Hugh.


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PostPosted: 09 Jul 2018, 18:12 
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Location: Arizona, USA
Hi, The difference in capacitance is within the tolerance of most parts of that vintage so the swap should not be all that dramatic....however. If the original is a non-polar electrolytic then it may have "dried" out and is no longer the value expected. This could make a big difference in the sound. Depending on where in the crossover it is used the apparent volume could change a lot. The frequency response would also be different. Personally I would go with a new capacitor and keep the old coils and resistors. They should not change in value over time. Since our ears are the end result of our audio adventures....it makes sense to use whatever sounds best to us. So really while the old caps may not be up to snuff if they sound better to you there is no harm in keeping them.

Good listening
Bruce

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PostPosted: 10 Jul 2018, 05:37 
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Joined: 02 Jul 2018, 04:11
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Location: Ghent Belgium
Thanks a lot Bruce.
Will try and change caps for new ones (I already bought them).
Will not fail to keep you informed.
Cheers,

Hugh.


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PostPosted: 13 Jul 2018, 05:14 
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Joined: 02 Jul 2018, 04:11
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Location: Ghent Belgium
Hi Bruce,

OK, changed the caps.
Found out that the muddy sound I heard was from one of the speakers. There was some rubbing inside the coil of the right woofer! Caramba!
Fortunately, the old Wharfedale woofers can be completely disassembled from the back (magnet kept in place by four bolts and an adjustment screw in the middle).
So I opened it and got to the voice coil, which was still in good shape. Cleaned it with some contact cleaner and put the magnet back on. Tweaked it meticulously until I felt it working free: the good sound is back! Probably more luck than skill!
Think I'm not going to look further: the speakers now sound very good (nice British vintage bass) and I hope I'm not going to damage my 8 Ohms amp with 4/6 Ohms drivers. 8 Ohms would have been better but I don't know if I can change this and how.
Currently listening to Pink Floyd's "Wish you were here" on my Dual 1219:... awesome!
Thanks again for your advice and suggestions!
Cheers,

Hugh.


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