Restoration of vintage speakers.

[SIDEWINDER18X]

Hello Everyone,
It's great to see people here who have deep passion and crave for vintage speakers. It's also very appreciable to see that how keen & particular they are on each and every aspect in selecting the accurate parts and precision to get them back to their original state or form.
In doing so you should always keep in mind some very important points if you want to get the job done accurately & correctly.

1. Re-magnetize the magnet before you recone.
Vintage speaker build around Alnico magnet will have a loss in their magnetic strength, even if they were not hard driven in any theater or in any pro installation or usage. This is due to aging and other circumstances. If you can measure gap strength with a gauss meter you will come to know about it for sure. So re-magnetizing is strongly recommended. Take a gauss reading before and after the process. You will see the difference.

2. Never coat or spray any lacquer or emulsion on the paper cone surface.
I see lots of misconceptions in this regards. Vintage speakers are built around Light, Soft and Felted cones. They are made as such for their unique tone. Its due to this they have a shorter life span.
Do not ever spray water proofing chemicals or doping lacquers on to the cone surface. It will alter the tonal characteristic of the speaker. Spaying any liquid will be absorbed by the cone pulp like a blotting paper. Hence the natural tone of the cones will change.

(But though there are several speakers of the past & present which do have treatment on them. Some for weather resistance, some for producing a unique tone out of them & some just for cosmetics such as "wet look".
The same formula cannot be applied for every speaker).
Vivek

 

[GeorgeO]

Interesting post, and interesting talking to you about your deleted post. I am doing an Altec 2 way, and plan to coat only the surround with your 'goop", no snake oil coating of any kind of the extremely light paper cone. I look forward to meeting you in Calcutta when I visit there later this year.

 

[GeorgeO]

Just for my info, what about pro sound speakers that are used outdoors? Do they need any water resistant coating, or any coating?

 

[wlg]

I have been given vintage Yahama NS-451 speakers (1974) in near mint condition, the 8" cones are white but after years have got brown speckles on them, any way of getting them clean.

 

[ranjeetrain]

Hello Everyone,
It's great to see people here who have deep passion and crave for vintage speakers. It's also very appreciable to see that how keen & particular they are on each and every aspect in selecting the accurate parts and precision to get them back to their original state or form.
In doing so you should always keep in mind some very important points if you want to get the job done accurately & correctly.

1. Re-magnetize the magnet before you recone.
Vintage speaker build around Alnico magnet will have a loss in their magnetic strength, even if they were not hard driven in any theater or in any pro installation or usage. This is due to aging and other circumstances. If you can measure gap strength with a gauss meter you will come to know about it for sure. So re-magnetizing is strongly recommended. Take a gauss reading before and after the process. You will see the difference.

2. Never coat or spray any lacquer or emulsion on the paper cone surface.
I see lots of misconceptions in this regards. Vintage speakers are built around Light, Soft and Felted cones. They are made as such for their unique tone. Its due to this they have a shorter life span.
Do not ever spray water proofing chemicals or doping lacquers on to the cone surface. It will alter the tonal characteristic of the speaker. Spaying any liquid will be absorbed by the cone pulp like a blotting paper. Hence the natural tone of the cones will change.

(But though there are several speakers of the past & present which do have treatment on them. Some for weather resistance, some for producing a unique tone out of them & some just for cosmetics such as "wet look".
The same formula cannot be applied for every speaker).
Vivek

Great Vivek!

I have always wondered how can one enjoy music on speakers made with drivers with decades old weaken-ed magnets. It has always stumped me. I never mentioned this to avoid hurting the sentiments of vintage gear owners. Good to see someone coming up this.

Will be keen to see someone try these and post their pre and post impressions.

 

[reubensm]

I have been given vintage Yahama NS-451 speakers (1974) in near mint condition, the 8" cones are white but after years have got brown speckles on them, any way of getting them clean.

In my opinion, just let them be the way they are. Not a good idea to spray anything on vintage paper. A softened vintage cone that dries, tends to crack.

 

[viren bakhshi]

Well, I've just reconed two old Altec 416-8A drivers with cone and voice-coil assemblies from Great Plains Audio. Ran them in for some time, then tested them for their Thiele-Small parameters:

Free air resonance : 18.9 Hz (sample 1) / 19.2 Hz (sample 2) / 24 Hz (Altec spec. 1987)
Equiv. volume compliance : 28 cu.ft. (1) / 30 cu.ft. (2) / 22.9 cu.ft. (Altec spec. 1987)
Total Q , Qts : 0.24 (1) / 0.25 (2) / 0.23 (Altec spec. 1987)
Electrical Q, Qes : 0.24 (1) / 0.26 (2) / 0.24 (Altec spec. 1987)
BL factor : 15.8 (1) / 16.0 (2) / 16.0 (Altec spec.1987)

Pretty darn close to the published Altec specifications for the 416-8A driver. Perhaps too much is being made of falling performance in these vintage drivers.

Who knows how old these drivers really are, how long they were played in the cinema hall that they were in, and the sort of storage they were in. But perform they do!

Regards,
Viren

 

[viren bakhshi]

Hello Ranjeetrain,

You were here about a week ago, and listened to the Altec/JBL fitted horns. Both are vintage drivers, restored with new cones and diaphragms. The chassis and magnets are untouched. Don't know how old the drivers are, but pretty old all right.

Did you find a lack of performance in the drivers? We had a pretty extended session. You would have heard if the drivers were not up to the mark.

Regards,
Viren

 

[SIDEWINDER18X]

Just for my info, what about pro sound speakers that are used outdoors? Do they need any water resistant coating, or any coating?

Hi George,
Most of the pro sound cones are treated with water resistance additives during the formation of the cone itself. Though it is not visible.
Some are coated from the front and some from both sides, providing resistance to extreme weather conditions.
These are so tough that if you spill water on them and it will not soak in.
But there are also many cones in pro sound which are strong but soft, heavily felted but are not water resistance. They produce some of the outstanding tonal quality which are legendary.
Treating, coating, spraying are the aspect to be decided to the design philosophy behind the birth of any particular speaker by its developer.
They do this to achieve their goals and target for their prototype driver keeping in mind for a particular application.
And by the way, many hi-fi cones are also made similarly.
Vivek

 

[GeorgeO]

Interesting observations Vivek.

 

[SIDEWINDER18X]

I am into the recone job from quite some time now. I had reconed over 1000 vintage drivers and more to that ferrite & neo drivers till date. I take a gauss reading of each and every driver which is on my table before I do the job. I have noted & maintained a very long list of gauss reading chart for my reference.
Ferrite & Neo drivers have negligible loss in their strength. But at-least 90% of the Alnico driver needed recharging. What I say here is what I had seen and practically done.
Vivek

 

[SIDEWINDER18X]

Hello Ranjeetrain,
You were here about a week ago, and listened to the Altec/JBL fitted horns. Both are vintage drivers, restored with new cones and diaphragms. The chassis and magnets are untouched. Don't know how old the drivers are, but pretty old all right. Did you find a lack of performance in the drivers? We had a pretty extended session. You would have heard if the drivers were not up to the mark.
Regards,
Viren

Long time back I had the privilege to get a box packed Vintage JBL L110 boxes from somebody brought in from the US. It was in mint condition, untouched and never played. I cut opened the packing for the first time.
This L110 was the 1st generation 3 way box with 10 incher alnico woofer, 4" ferrite cone mid & 1" ferrite dome (n.b: 2nd generation L110 was fitted with the same 10 incher with ferrite magnet).
Unfortunately the foam surrounds on the 10" were gone (rotten).
I got replacement foams rings from abroad and re-foamed them.
After reviving them and listening them for several days through different sound sources. I was not happy, but disappointed to find lack of output in the upper mid bass output of the 10 inches. By comparing the same content side by side with another similar box, I found out most of the important music spectrum of that region completely missing.
It was not possible to take a gauss reading in a ready driver. Seeing that I straight went for recharging them. Luckily that time I had a "C" Charging fixture, which could charge a completely assembled speaker with the frame.
After the process these boxes had made my listening experiences quite pleasant for many years.
Vivek

 

[ranjeetrain]

Hello Ranjeetrain,

You were here about a week ago, and listened to the Altec/JBL fitted horns. Both are vintage drivers, restored with new cones and diaphragms. The chassis and magnets are untouched. Don't know how old the drivers are, but pretty old all right.

Did you find a lack of performance in the drivers? We had a pretty extended session. You would have heard if the drivers were not up to the mark.

Regards,
Viren

Hi Viren,

It's a tricky question. Unless I know how these drivers are supposed to perform (how they performed had they been new) it's unfair for me to answer that question. I can't answer that question without speculating, something I don't like doing. I can, however, definitely talk about how did the drivers that I heard sound. And that I will. (Sorry it's been a while but I haven't talked about it, primarily due to confusion about the approach of description. Anyway, I'll pen down my experience in the Lyrita Horn Grande thread).

Regards.

 

[viren bakhshi]

Hello Ranjeetrain,

Thanks.

Not a tricky question at all. The performance is very easy to observe - does the system make music? Is it balanced to portray music realistically? Just listen, and you have your answer.

(Ah, this is just a forum, and let's keep it that way. It will be great if you can just pen down your impressions - don't have to formalize them).

Regards,
Viren

 

[viren bakhshi]

Hi,

This is more of a general comment. And I will be frank. There are more than a dozen members on this forum who have been listening to restored vintage gear for many years. And they know their music, and their ears recognize good sound. Why they have moved to vintage gear is because they have been disappointed in the offerings of the majors.

So, why speculate as to the quality of good vintage gear? Fix up with any of these members, and go listen to their systems. Your own ears will tell you if the music is good. And, learn to trust your ears. Then, form your impressions!

Viren

 

[GeorgeO]

I will go one step further, and say that in general some of the comments/posts that I am coming across these days lack common courtesy. Please recognize that different people like different things, so Vive le difference. No need to be dogmatic, self righteous, or lack tolerance. This forum has in the past been a place with lost of good will and I hope it remains that way, going forward.

I bet a lot of the posts that are coming up would never be couched in the language used if the same people met face to face! I'm not going to start pontificating on improving manners, etiquette etc.

 

[GeorgeO]

Going back to topic:

Vivek:

So whats your take on altering a vintage driver's cone by "treating" it? In other words, if a paper cone had certain original characteristics, what happens when these are modified? Does the driver lose any of it's originality? Is that for the better or for the worse?

I am going to be coating the surround on my Altecs with goop, that is a normal practice, well established over many decades, and recommended by many including GPA. What about cones?

I probably could have exercised the option of checking the Gauss value on my vintage drivers before reconing them. I personally don't know of anyone here in Bangalore who has the gear to measure this, unfortunately.

Thanks

 

[SIDEWINDER18X]

Going back to topic:
Vivek:
So whats your take on altering a vintage driver's cone by "treating" it? In other words, if a paper cone had certain original characteristics, what happens when these are modified? Does the driver lose any of it's originality? Is that for the better or for the worse?
I am going to be coating the surround on my Altecs with goop, that is a normal practice, well established over many decades, and recommended by many including GPA. What about cones?
Thanks

Hi George,
Applying surround dampener to the cloth edge is perfectly ok and is a must for untreated cloth type suspension. There are various reasons behind this.
Coating or applying any kind of dope on your vintage Altec cone could be a negative approach. Definitely the tone will change and so will be the possibilities of the cone getting damaged in a long run.

And one important aspect to understand. The coating or doping which people are referring here .... do they know the coating or spaying formulation which they intend to use ?.
Doped lacquer and other formulations used in many drivers are mostly industry secrets which are never relieved by the industries. Some are done initially by the cone manufacturer as their regular routine for specific models, some on specified oem specs for their clients.
Some are done by the end manufacturer sometimes for a desired tone & damping of unwanted cone resonance (eg: ATC, PEERLESS, VIFA, MOREL, ELAC and others) , some time to add mass to get a lower fs (eg in early JBL's their "AQUAPLAS COATINGS")
some for weather resistance (eg: 18 Sound, B&C, Selenium .... )
& some only for cosmetics, for the "wet-look" effect.
Not only cones, HF & MF fabric & silk dome diaphragms are also coated for a purpose. Not only fabric but hard Phenolic & Mylar are sometimes vapor deposited with hybrid metal flakes. Aluminum,Titanium & Beryllium too are chemically treated to overcome lots of issues.

The point here is that until & unless you are expertize in doing this you should always think over it. Do not assume or draw conclusions on fantasies.
Vivek

 

[manoj.p]

I will go one step further, and say that in general some of the comments/posts that I am coming across these days lack common courtesy. Please recognize that different people like different things, so Vive le difference. No need to be dogmatic, self righteous, or lack tolerance. This forum has in the past been a place with lost of good will and I hope it remains that way, going forward.

I bet a lot of the posts that are coming up would never be couched in the language used if the same people met face to face! I'm not going to start pontificating on improving manners, etiquette etc.

probably because too many business interests at stake?

 

[kuruvilajacob]

I was going through this post for the first time today. I am using KLH Model 5 speakers in my main listening room. When I first got them, they were sounding lousy. Hardly any sound was coming out of them. I think they were unused for a few decades. Fortunately, none of the drivers were touched. So I surfed the net and was inspired to restore them by replacing the caps with imported ones and as per their original factory instructions, the cloth surrounds needs an application of a rubberized coating to ensure the air does not leak out as it is acoustic suspension system designed by I think Henry Kloss . The result of the restoration was magical. I was so happy with the results that I have restored a Pioneer CS 99 A speaker and I am planning to restore a AR 925 E speakers with replacement of caps and surround. May be I should think of re-magnatizing also after reading a few posts here.