NAD Series 300 - Uncommon Restoration

Hey folks!

I have just started yet another resto project. This time, a fairly uncommon creature, a NAD 300, 3-way loudspeaker. I bought these from eBay back in December from an unknown seller in Philly. The AK Pony Express worked out in incredible fashion and I just took delivery of the speakers last week!

I have developed a strange fascination with NAD components, and these speakers, which were the flagship in the late 80s, were a short-lived attempt by NAD to develop speakers from the ground up and using off the shelf components.

I hope you guys enjoy the pictorial and will follow the project. Here's what's on tap.

1) Confirm operation of all drivers
--- All drivers but one tweeter are working and sounding great! Both midrange domes were dented in. One tweeter was dented in. One woofer dust cap dented in. I vacuumed them all out and they are holding shape for now, with minimal dimpling.
--- I believe these drivers to be an adaptation from a/d/s/ drivers from the same era. The drivers look very close to the L9e, but without the sticky coating on the domes.
--- I plan to rebuild the broken tweeter if possible. If not, I will replace both tweeters with a/d/s/ replacements.

2) New rubber surrounds for the woofers. The rubber has hardened and rotted. Will order new 10" surrounds and get them in top shape again.

3) Recap the crossovers and clean the tweeter adjustment dials.

4) Sand and refinish the cabinets… Color suggestions!???
I was thinking a dark mahogany stain, or mango wood?


5) Repair the broken grill frame and recover the grills.

6) Have new labels made.

7) LISTEN FOR EVER AND EVER!

Here are the photos:







The cabinets are VERY heavy and dead silent. Lots of internal bracing.






Back of mid
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Mid face plate




Back of woofer


Cracked surround
]



To be continued….

Continued….

Welcome back to November 1986!


Tweeter dome


Tweeter Back
]

Underside of dome. Notice damping material inside the magnet as well as behind the dome. Are these ADS/Braun domes, or something else?? The Patent number points to a US company!


Broken grill



a/d/s/ L9e for comparison

Trying to fix the tweeter. The voice coil is good. The tinsel wire is very very thin. I think it got overcooked and broke near the end. Here's a close up of the new tinsel wire routing.

Those look like they were built in the same plant that built the Altec Lansing speakers after 1985. IIRC, it was also the same plant that assembled much of the Proton products of that time, too...

Regards,
Gordon.

You think those drivers, T637 and M428 are altec drivers with NAD face plates?

Not the same drivers, but definitely similar in construction.

The Altec dome drivers of that era, used polyamide diaphragms.

Regards,
Gordon.

NAD Canada was not much help at finding info.

Bet those are going to sound really nice when you have them back to specs. I saw a pair in a pawn shop in Indy about a year ago and almost pulled the trigger but I have waaaay more toys than I need already.

Quick update: NAD Canada doesn't know anything about these speakers, so I contacted Richard So, former ADS tech from Massachusetts who now resides in Arizona and sells his wares on eBay. Richard confirmed that those components are all ADS, so ADS domes and voice coils will be compatible with the magnet assemblies. The difference between these domes and ADS domes is that these have the sealant applied, which is a thin coating to the domes to make them air tight, but not the "sticky" outer coating.

The cost to rebuild the drivers is pricey, but might be worth it.
Tweeter $45 each to rebuild.
Midrange $55 each to rebuild.

I might just have the tweeters done and live with the midranges as they are for now until I have fully assessed the speakers. Only one tweeter is out, but would rather have both done and matching.

The broken frame is already epoxied and ready for new cloth too!

A most worth while project here-be looking foward to you eventual review- bet you will be impressed. I have learned a lot on the driver sourcing here!
DC

Repairing broken grill frame and recloth.

This is great summertime project, and looks to me that it's going to turn out great.

Tube

According to Richard So, these are not ADS HF/MF drivers, but they will fit ADS domes.
According to Bill from Great Plains Audio, they are not Altec drivers either.

The mystery continues.... They are definitely US made by the look of the writing on the back of the magnet. I can't match them up with anything from Braun, ADS, Heco, Magnat, Visonik, or Philips. WHO MADE THESE DRIVERS FOR NAD!!???

Here's some more history:

Apparently, NAD approached both ADS and Braun in the 80s to build the NAD 20 and NAD 30 speakers. Eventhough ADS owned Braun, the job was bid separately and the Braun factory won. So, Braun made the same drivers for both NAD and ADS. The model equivalent for the 2-way is the L690, the 3-way is the L990. They are identical designs with identical drivers, though the ADS version has the drivers mounted off center on the enclosure.

But the 200 and 300 models by NAD were not made in West Germany, and the drivers were sourced and assembled somewhere in the US by someone. Just don't know who.

Do the monickers T637 and M428 mean anything???

baco99 Always a pleasure reading your posts. I also respect your work.

Excited to see the outcome of the resto.

Kudos!

Thanks DK.

Guess what? FOUND THE OEM SOURCE!
Phase Technology was making OEM drivers at this time in the 1980s and 1990s. The ADS tech that I mentioned before (online handle "speaker" from diyaudio.com) directed me to them. I did some eBay searches to see what their tweeters looked like. Sure enough, 3-hold bolt pattern, soft fabric domes, and look at the writing on the back and the model designations used!

So, I emailed Phase Tech, which is a division of MSE Audio, to see if the had any diaphragms that would work, any information about the speakers, and any marketing materials or specifications. I also asked if they supplied the woofers. The tag on the woofer "586 5.98" might be their ID tag as well.

Getting closer... Glad I didn't jump on any ADS drivers yet...

tweeter from Phase Technology Model PC60(circa 1986) has the same Patent number.

moebuster said:

tweeter from Phase Technology Model PC60(circa 1986) has the same Patent number.

Click to expand...

Do they have a "T" number or a number printed on a price tag looking thing.

a round gold sticker with a 6 on it

and

date 0307 86
T636

Cool. Thanks for doing that.

no problem for a Karma brother.