Gentle reader,
This has been a long and interesting challenge in (sort of) recreating my first stereo from 1976, then I was a mere 19-years-old. Here is a link to the previous chapter which also has links to earlier two and other related posts:
PART THREE: Reliving the 1976 sound of Dynaco PAT-5 preamplifier and SWTPC power amplifier!
PART THREE: Reliving the 1976 sound of Dynaco PAT-5 preamplifier and SWTPC power amplifier!
Thanks to the Polish store: Retro Audio | strona główna which has a store on eBay, I was able to buy an exact replacement for the SEAS H 086 tweeter that came apart in shipment from the seller in New York. It arrived well protected and he used stamps, so I have some recent Polish stamps to add to my stock book. Not that I have actively collected postage stamps since the 1960's. There is another one available on eBay, but it is in Australia and he wants way more money for it.
While this image appears to be the same one from the previous post, it is not. In the middle of the left stack resides the newly working Dynaco A25XL speaker. After I installed the tweeter, IT was the only driver working!*
Close-ups of the left stack, above and right stack, below. Bottom speakers are my $9.99 thrift store found KLIPSCH KG4 speakers with the bamboo stands. Atop are the heavily modified speakers formerly known as Radio Shack's Minimus 7W. The only parts that remain are the wooden cabinets and tweeter frames. I wrote several posts detailing the steps involved in modifying them. BTW, those are woven Kevlar woofers and FMT ribbon tweeters.
I believe the A25XL above had water dripping on it in the past.
Above is the magnet and pole piece of the separated tweeter.
Below is a side view of the domed cushion that is normally inside the tweeter dome.
After several attempts I was able to get the two pieces back together. Talk about STRONG magnets! Whether it is viable, I do not yet know. I will test it soon.
The photo above shows the visual difference between the A25XL's tweeter (left) and regular A25's on the right. Aside from being 50% smaller, it is 3 dB more efficient, and crosses over 300 Hertz lower.
*Now, as to my discovery that the woofer of the same speaker was also not working. I removed it and found that the impact (which did not harm the cabinet) that broke the tweeter's magnet off also dislodged the two grommets that hold the terminals on the woofer and connect the crossover's wires to the voice coil wires. Below is the woofer from the A25 to show you what it is supposed to look like.
The voice coil wire which passes through the center of the grommet (easier to see in the upper photo) had broken off in the impact. I found a suitable wire, stripped it, and wove it to the coil wire and soldered them together. Then threaded the new wire through the grommet and soldered it to the lug. I used super glue to reattach both grommets to the diecast aluminum woofer frame. Reinstalled it in the cabinet and hooked it back up to the system.
It sounded great and for the first time, I heard two A25XL speakers play together. I am keeping my solo A25 speaker. Since the Dynaco PAT-5 preamp has two pairs of outputs, I may set it up as a mono speaker. I've got lots of mono LP records.
NOW, one other thing. The turntable I bought which started this whole retro-revival is a LUXMAN PD264. I bought it via eBay and the seller didn't know of the importance of removing the heavy platter and wrapping it separately from the rest of the turntable. It came loose and cracked the dust cover and I thought damaged the tonearm.
Turns out the tonearm was only all kinds of misadjusted. The owner's manual and service manual do not describe just how the lifting mechanism works. One implies there is hydraulic fluid involved. My first turntable was a B.I.C 940 and it kept losing the lifting fluid.
The shaft that sticks out of the right side of the tonearm is what one rotates on the motor and supposedly raises the tonearm.
As the record finishes, there is a little "L" shaped wire that the tonearm touches and the arm is supposed to lift and turn off the motor. I got the latter to happen, but it has never lifted.
SO, I did some research and found about the "Q up" tonearm lifter. Here is a link to their website that does a great job of explaining how it works. THE Q UP - Automatic tonearm lifter for manual turntables and tonearms - thorens q-up audio technica AT6006a At first, I balked at the price of $50. When I arrived, more so, but as I studied it and tried it out, I realized there is a LOT of engineering in the Q up and the product fills a HUGE niche due to the vast number of manual turntables being made and sold these days.
It comes with several spacers of varying thicknesses to help it work with most manual turntables. Unfortunately, the PD264 is not one of them.
I determined that if I cut the thinnest spacer in two it should work. It does and below are a series of photos showing it installed on the LUXMAN turntable.
If you are familiar with the PD264 turntable, you can clearly see that I had to defeat the little "L" shaped trigger assembly that normally tells the tonearm to lift at the end of the record and shuts off the motor.
One can easily adjust the height and speed the Q up lifts your tonearm.
You can see here, that my task of cutting the spacer in two was....a bit tricky. Yet, despite the appearance, it is now the needed thickness. I used Blu Tack to join the spacer to the base of the Q up. It comes with self adhesive sticker to perform this task as well. One can see one of the adjusters on the front of the Q up. It slides up and down in the slot. The other adjuster also slides and is on the back of the Q up. Not visible in any of these photos.
The final task is the clean up the appearance of the A25XL speakers and use Quakehold! to secure the totem-stack of speakers. I want to incorporate the silver, formerly Radio Shack's Minimus 11, speakers as well. Yes, they too use the same FMT ribbon tweeters. They are quite a bit larger than the diminutive 7W speakers.
The only way to do that safely is with reusable adhesive as shown in this prior post: Earthquake Proof your speakers! Amazing "Reusable Adhesive" will hold my Klipsch KG4 speakers firm!
I won't bore you with that particular part of the process. I love the way both the formerly Minimus speakers sound and since I have two complete systems here, why not?
Thanks for looking,
Scott
