Which driver is the "real" Fe103a??

[planet10]

Re: Fe103 mods

By the way, I saw a pic of your's yesterday on Ebay, and a driver was seen with some kind of "mastic" around the basket/magnet joint. What is it for? to reduce some ringing modes?

Ductseal, to do exactly that

dave

 

[planet10]

Re: TQWT suggestions anybody?

I have previously built a TQWT after Jean Hiraga's book, it is planned for 13cm drivers or so, and I it is well built, but I only had under hand a so so car full range driver.. but even then, it was sounding not bad at all, so, what would be a nice driver suggestion to buy for them??

I imagine the cabinets could accept drivers from 12 to 15-16cm..
]

Driver size (other than physically fitting the driver) actually has no direct impact on what would work. The Q, Vas, and Fs.

I assume it is a classic voigt? These are much more often than not, less than optimal. I'd suggest plugging t he cabinet into MJK worksheets and play with drivers -- given a fixed length you will have a small range of Fs to work in. You will likely find that restricting the terminus, will help a lot in getting a good response.

I expect GM will have something to say... he has a much better intuitive grasp on what works & what doesn't

dave

 

[Sylver300B]

TQWT suggestions

Driver size (other than physically fitting the driver0 actually has no direct impact on what would work. The Q, Vas, and Fs.

I assume it is a classic voigt? These are much more often than not, less than optimal.
dave

Well, it looks quite a bit like this: (see attached image) and the measurements are 90cm high, 18cm wide, and 25cm deep. (aprox 38inch x 7 x 10)

What are the spreadsheets your refer to? I am a newbie when it comes to speaker specs, I know.. Just wanting to learn.

Thanks!

Sylvain

 

[planet10]

Re: TQWT suggestions

Well, it looks quite a bit like this

A classicvoigt

What are the spreadsheets your refer to? I am a newbie when it comes to speaker specs, I know.. Just wanting to learn.

http://www.quarter-wave.com

dave

 

[Bill F.]

The best (and rarest) of these are the holey basket Coral

I agree. Funny thing is, prices on these seem to lag way behind the Foster versions. Strange how the market seems to have "discoverd" one and not the other yet.

IMHO, these Coral versions are consistantly far and away the best bargain in vintage FR drivers available today. I also think they're a bit prettier than the Fosters. 😎

 

[warnpeas]

Is this a Fostex 103 variant?

😕

Are these F 103 variants?

On the back is printed: 2W 4Ohm SP-10F5 and 92151240.

They came out of a set of cabinets that each had one driver and no manufacturer info.

Thanks,
Warren

 

[planet10]

Re: Is this a Fostex 103 variant?

Are these F 103 variants?

If they are 4'/100mm yes. Do you have a picture of the front?

Recent orrespondance with a gentleman in Japan -- who was buying these when they were new -- i have "discovered" 2 more fairly large OEMs. Atomix and Onkyo. The basket shape on these is similar to some i would have originally called Nationsl (Panasonic/Technics/Matsushita), but now know to be Atomix.

dave

 

[planet10]

And while i'm here... here is a pic of a set of recently modded Radio Shack 40-1197 i did up for a customer.

The affordability, and accessibility of this driver probably did more for the popularity of the Fostex drivers in North America than any other single other thing.

dave

 

[tleonard]

Hmm, those drivers look oddly familiar... 😀

Bound for Zigmas in a week or two after they arrive.

travis

 

[warnpeas]

Fosters in question

Thanks for getting back to me. just go the (Atomix) on ebay and already have the phase plugs coming. I am thinking of putting them in the Solo 103. Have you heard anybody else's feedback on this enclosure?

Here's a pic of the front of the driver.

 

[planet10]

Re: Fosters in question

Thanks for getting back to me. just go the (Atomix) on ebay and already have the phase plugs coming. I am thinking of putting them in the Solo 103. Have you heard anybody else's feedback on this enclosure?

You'll have to help me on the eBay auction... a search of Atomix turned up mostly HotWheels & Clocks 🙂

Bass Relex cabinets are the kind of cabinet that is most sensitive to the speakers T/S parameters. The Solo 103 is a very attractive box -- i've used it as inspiration for a box for the new CSS FR125 -- but i would hesitate to build one verbatim. The parameters of these older drivers (i've not ever seen yours) typically have higher Fs & higher Q than the FE103 the Solo 103 was tuned for, so the liklihood of it being spot-on or even close is small.

A design like the Solo 103, but tuned for your drivers -- if their parameters are close -- is probably doable tho.

dave

PS: just got to your email

 

[tomtt]

not a 103...

yet looks somewhat simmilar to the css fr125
and looks good any way-

http://www5b.biglobe.ne.jp/~tritium/4a70.htm

thanks dave for the pictures

 

[KT]

Hello Dave and all,

I just received a pair of Sony/Coral Fe103a's from Bill. Pretty cool. I haven't used them yet, just looked at them. They look so much bigger in the pictures.

Regarding the rubber coated cloth surrounds on these, there are a few small areas where the rubber has come off of the cloth. The biggest area is about 3mm x almost 1cm or so.

What do you recommend for covering up these exposed areas? I was thinking some sort of brush-on polymer or rubber coating, but I know absolutely nothing about these things in regards to a speaker surround. Any recommendations or tips would be appreciated.

Also, one of the cones looks slightly "furry". Sort of the look of paper that's been slightly abraded (fibers sort of loosened and fuzzed up). I'm assuming that this is not a problem? I understand that one of the mods involves coating the cone with something like puzzlecoat or dammar. I'm planning on using some C37 lacquer, myself, so I assume this will mat down the slightly furry area and "bind" those loosened fibers together. I hope so, anyway.

I'm very interested in purchasing a pair of your phase plugs for the Corals. Is this something I can install myself, or would I need to send them to you?

Thanks!
KT

 

[KT]

Re: Re: Fosters in question

Bass Reflex cabinets are the kind of cabinet that is most sensitive to the speakers T/S parameters. The Solo 103 is a very attractive box -- i've used it as inspiration for a box for the new CSS FR125 -- but i would hesitate to build one verbatim. The parameters of these older drivers (i've not ever seen yours) typically have higher Fs & higher Q than the FE103 the Solo 103 was tuned for, so the liklihood of it being spot-on or even close is small.

Hi Dave,

I'm building a pair of cabs for a pair of Altec 405-8A drivers based on the following plans:

http://www.geocities.co.jp/Technopolis/5053/sp/405B.htm

I was concerned when I read your post regarding the sensitivity of Bass Reflex cabs to T/S parameters because these cabs are designed for the Altec 405-8H driver, not the 405-8A. I've searched the web for specs on the 8A, but haven't been able to find anything. I decided to go ahead with the project thinking that I may get some acceptable results.

Some of the other Altec driver specs are listed here, however:

http://www.greatplainsaudio.com/Thiele-Small.html

I know very little about speaker design, but it seems that most of the design and tuning of BR cabs is an effort to get a good and proper bass response from a given driver. What is the worst that can happen if I put a driver like the 405-8A in a cabinet that wasn't designed for it? Would it primarily affect the bass response, or are there some other negative effects that might pop up?

Thanks,
KT

 

[planet10]

Re: Re: Re: Fosters in question

Regarding the rubber coated cloth surrounds on these, there are a few small areas where the rubber has come off of the cloth. The biggest area is about 3mm x almost 1cm or so.

You might be better just to redistribute the coating that is there... i use acetone & QTips (a heat gun sometimes helps too (to warm things up before applying the solvent.

Also, one of the cones looks slightly "furry". Sort of the look of paper that's been slightly abraded (fibers sort of loosened and fuzzed up). I'm assuming that this is not a problem? I understand that one of the mods involves coating the cone with something like puzzlecoat or dammar. I'm planning on using some C37 lacquer, myself, so I assume this will mat down the slightly furry area and "bind" those loosened fibers together. I hope so, anyway.

C37 should fix them up nice.

I'm very interested in purchasing a pair of your phase plugs for the Corals. Is this something I can install myself, or would I need to send them to you?

The Corals need a phase plug that we normally don't have. It is a bit smaller than for the Foster FE103A, so either needs to be custome built or you need to sand down a set of FE103A plugs (some work but doable -- picture of some 16 ohm holey basket Corals with sanded down plugs.

dave

 

[planet10]

Re: Re: Re: Fosters in question

I was concerned when I read your post regarding the sensitivity of Bass Reflex cabs to T/S parameters because these cabs are designed for the Altec 405-8H driver, not the 405-8A. I've searched the web for specs on the 8A, but haven't been able to find anything. I decided to go ahead with the project thinking that I may get some acceptable results.

Even if you were using the "official" driver, it would be well to measure the actual drivers and tune the cabs to them -- as drivers age their parameters will wander -- ie alnico tends to have its magnetic strength decline with age (giving us higher Q, less effecient vintage drivers -- i look forwrd to the day i can get at a facility that can remagnetize old drivers).

So even finding T/S parameters for your driver only gives you a vague (possibily misleading) set of numbers.

dave

 

[KT]

Thanks for the advice, Dave.

I may contact you soon about the specifics of having those custom phase plugs made for the Corals.

How does one go about measuring the driver specs? If you have time to explain or just point me to a site with information about it, I'd be most grateful.

Thanks,
KT

 

[planet10]

How does one go about measuring the driver specs? If you have time to explain or just point me to a site with information about it, I'd be most grateful.

By far & away the easiest is to use FuzzMeasure (and the excel worksheet for converting the numbers measured into T/S parameters). Not everyone is fortunate enuff to own a Mac running OS X 1.3.9 or newer thou....

The longer method is described here: http://www.diysubwoofers.org/measure.htm

There are other slightly different techniques as well.

dave

 

[KT]

Thanks Dave,

I'll look into Fuzzmeasure.

Luckily, I'm running OS X Tiger 10.4.2. Great operating system!

Best,
KT

 

[planet10]

Luckily, I'm running OS X Tiger 10.4.2. Great operating system!

there you go... i'll mail you the spreadsheet. You will need to make a simple jig (min of a 4mm stereo phone cable, a 1k R, and about an 8R reference.

dave