Gale GS401 Re-foam Project

There was an equivalent Peerless 8" as used in later Gale 301's but it also had a foam surround so any left alive will need re-foaming now too.

The crossover board was a right bugger to remove; those staples were designed for permanent fixture. That and the amount of glue used makes the board effectively unmodifiable. I doubt that I could rescue the inductors without destroying them; as it is, the coils are quite loose and only held in place by the cable ties. You can see at the top that one capacitor has exploded meaning that this crossover was already inoperative.

The pot tracks are in a bad way and I had to exercise them a lot in order to take measurements in their nominal centre positions. Interestingly, the mid adjuster is almost at max level while the tweeter is closer to centre position. This has helped me to finalise the circuit shown in post #52.

http://farm8.staticflickr.com/7364/8...609ea796_b.jpg

Crossover Shopping List

Resistors (all Mills MRA12)
0R82 x 2
3R9 x 2
6R2 x 2

Capacitors (all Supersound polypropylene)
4uF x 4
5.6uF x 2
6.8uF x 2
30uF x 2

Inductors (all Wilmslow air cored)
0.15mH x 2
0.3mH x 2
1.8mH x 2
3.3mH x 2

Speaker terminals x 2

Thin ply board 220 x 160mm x 2

Id be tempted to try find some long thread terminals & use at least 1/2'' ply board.

I've gone for thinner ply, Andr'e, on the basis that it's thicker than the hardboard used. Long thread terminals already ordered ;)

Just for fun, Martin, here's my opinion of the Gale GS401A:

Quote:

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Originally Posted by system7

You can tell I am warming to this theme! Here's a mighty pretty loudspeaker, the Gale GS401A, that made everybody's jaws drop when playing Led Zeppelin's awesome Black Dog at 70's HiFi shows... :D

http://img196.imageshack.us/img196/9307/galegs401a.jpg

This baby had punch like an Acoustic Research unit and slam and presence like a PA speaker and detail like a Quad electrostatic, and I was left plain wondering what magic stuff was hiding behind those grilles that sounded so GOOD! I'm gonna tell you... :cool:

Firstly, the bad: it was a hideous 4 ohm load for amplifiers and had a reputation for frying them. :eek:

The good: two AR derived foamed 8" paper units wired in parallel as in PA applications, with a simple AR type inductor for an overall second order rolloff to take care of the bass up to 500Hz.

Next was a 4" foamed paper Peerless midrange in a simple sealed plastic tube that went up to 5KHz. The midrange was a particular strength, and considered better than the dull and peaky KEF B110 5" bextrene midrange used in BBC type monitors. Secret sauce? Probably the resistive padding used on the drive unit and after the second order midrange filters. Early models had 4X 10R wirewound padding the midrange and flattening impedance.

http://imageshack.us/a/img202/8380/g...01adrivers.jpg

From 5KHz, re-enter the excellent mylar domed Celestion HF2000 unit on a third order crossover. Often considered better than the KEF T27. Third order protects the tweeter from LF well, and acoustically matches a second order from the midrange. A lot to like there, and some ideas that found there way into the very fine and lively Wharfedale E70. You can read its history here.

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http://www.diyaudio.com/forums/multi...ml#post2886588

Flippin' great speaker. :)

Well Steve, you've just whetted my appetite even more. I certainly remember them the first time around, when they were just unobtainium to an enthusiastic teenager. I remember those early ARs too (like the 3a) and they certainly had clout.

Amusing that people lust after the chrome ones; I'm quite happy I found a pair in the wood finish. They don't need to show off, let the sound do the talking!

I'm currently doing the layout for the new crossovers. All parts received so I'll template everything in order to produce a matching pair.

I wasn't happy with my idea of using brass panel pins as uprights/supports. I've therefore ordered some proper silver turret tags from Hi-Fi Collective and am waiting for them to arrive. Otherwise, I'm all ready for the crossover build and re-foam sections of my project. I just need more free time!

Redesigned crossover ready to attach speaker driver cables. All components hot-glued into place. I designed it to keep the four chokes as far away from each other as possible, and to isolate the sensitive midrange section on the left (treble top-right, bass bottom-right). Silver turret tags used for anchor points. 4mm sockets protrude on the other side, ready for fitment to the rear cabinet access hole.

I'm going to try to rescue the Gale label complete with serial number from the old crossovers.

http://farm4.staticflickr.com/3815/8...6ce38a72_b.jpg

That is a very neat job Martin... :clapclapclap: