Marantz HD-660 speakers/crossovers

[David57]

Marantz HD-660
I love the look of these speakers, the black face needs a little work but the walnut is in fine shape and is one of my favorite woods.



And the covers are not too shabby either.



So this is my first purchase of quality vintage speakers, and they will be paired up with my Yamaha CR-2020 receiver. Since working with electronics is a budding hobby for me, I figured it would be best to keep my hands off the Yamaha, also new to me, which I “fixed” a bad channel on by tightening two screws.

That’s a lot of luck used up all at once and I don’t want to push it. So for my next project I thought I would take on the crossovers of these speakers.





These are 32 years old, and I was hoping I could get some guidance on improvements. Here are my thoughts:

Capacitors. I believe the two blue ones (in parallel one hidden behind the other) with the woofer are electrolytic and need to go, but I have no idea what kind the other two in cardboard tubes and sealed with wax are. There is one each for the soft dome tweeter and midrange driver. Brand name Electro Cap.

Resistors. I believe I have read some debate on the need to replace these, but I figure I will with ones that are non-inductive.

Inductors. One is a basic coil that I guess is an air core, another with the square center that is plastic, and two that I’m guessing are laminated core made of metal. All have 390 printed on them along with other numbers like 021-0 and 1022-0, if that means anything(values?). They are all made in the USA by Specialty Electronics. These I need the most help with, any options or should I leave them be? Does anybody have a schematic with values for this speaker?

Lpads. It looks like they have been replaced and I already cleaned them with DeOxit and they are silent.

Thanks in advance for any advice,
David

 

[GordonW]

The wax-sealed caps can sometimes be problematic- wax is not totally non-porous, and can absorb humidity over the years.

I'd just replace all the caps, and call it done. Resistors are fine unless they're broken or burnt up (neither is the case here), and so are inductor coils...

Regards,
Gordon.

 

[David57]

Changes by Marantz

Thanks Gordon for you input.

More to consider:

The other speaker’s serial number is earlier by about 4400 units, and there are differences in the crossovers, and subtle differences in the last digits of the speaker numbers.

Most noticeable to me is that the capacitance it doubled in the bass circuit and upped in the mid and high section of the newer unit. The two air coil inductors are matching numbers, but the two laminated ones differ as noted. The older unit’s differences are highlighted in this picture;



The debate (I am upgrading capacitors, polypropylene I am thinking, at least for the tweeter);

Should I rebuild both separate and to each crossovers original spec’s?

Should I consider the newer crossover an upgrade and build both using its capacitance specifications and resistor changes, not knowing the effects of the two possibly different laminated inductors on the older unit?

Or is there a hybrid option, like upgrading all capacitors to the newer units specs, and leaving all resistors and their perspective values alone?

Any help in simplifying this for me would be greatly appreciated.

David

 

[Big Tuna]

Very nice 660's. I love the HD's. I have 770's and DS920's, ohh and M10's. Very smooth sounding speakers, IMO. I had a pair of HD880's and I had those refurbed and tuned. My gawd did they sound good! I sold them to a marantz collector who was tickled to death to get them. he loves 'em. I believe the caps inside the wax are not electrolytic. I have some 660 crossvers that are not intact anymore but they still have the wax covered ones on them. I can open one up to check & see what they are, so we know for sure.

 

[David57]

Thanks BT. Would have loved to hear those 880's. The HD's are sweet speakers, great build quality, and from what little talk I see about them, I think they fly a bit under the radar, or maybe there just weren't that many of them? I am really looking forward to upgrading these.

Only one of the sealed tube caps was marked Mylar. From what I could find out that is a Dupont trade name used for polyester caps and it was in the tweeter circuit of the older crossover where it would make sense. The other three I have no idea.

Still have the two laminated inductors from that 660 crossover? I would prefer to match everything to the newest speaker. Unless someone knows that the speakers are of different spec, but I suspect (hope) not.

I think these might look, and sound better on a small stand, maybe 8 inches or so of walnut recessed back a bit on sides and front, or black MDF......but first things first.

By the way, if you work on these crossovers they are glued in on a masonite panel. I was able to get mine out with a flexible 1.5 inch drywall knife, sliding it under and working around the perimeter, through the glue. It was tough, but not as hard as working inside the box.

David

 

[bodegabandit]

Nice find Ive got a pair of HD-770's powered by a Yamaha & I think its a great combo.

 

[David57]

Thanks bodegabandit.

You know I have not even had a chance to wire these up to the Yamaha yet. I have to re-arrange things to make room for that big amp. For now I have been running them of a Denon avr-900.

 

[David57]

One of the biggest motivations for me to match these two crossovers was the thought that the newer one was an improvement. I thought more about this and there are other logical reasons for Marantz to make the change. A matter of economics or parts availability for instance, with possibly no noticeable affects on sound quality.

Given the fact that I have no experience with crossover design, combined with the lack of readily available specs of the two crossovers, I think it would be wise for me to refresh each one separately; keeping each ones individual spec’s intact.

In this case my current knowledge, or lack thereof, cannot support my struggle for symmetry. I will let that go for now and put my faith back in the original engineering.

So like Gordon suggested, I will replace the caps and call it done.

David

 

[Big Tuna]

Thanks BT.

Still have the two laminated inductors from that 660 crossover? I would prefer to match everything to the newest speaker. Unless someone knows that the speakers are of different spec, but I suspect (hope) not.

David

Yes I think they are still intact. Do you need numbers? I think it would be in your best interest to match them both because the drivers are the same. The fact that they are so far apart and having the differences, they will not match sound-wise. I will get mine out of storage tonight or tomorrow morning and let you know. As far as I can remember, the serial #'s on mine are pretty close.

 

[David57]

Thanks BT, that would be great, let me know what you find.

David

 

[Cogsinister]

They remind me a bit of JBL's, my L110's have the same caps in cardboard tubes (filled with sand by the way)

I wonder if JBL made them for Marantz ?

 

[David57]

Good call cogsinister, apparently there is a connection there.

"In 1976, Edmund (Ed) May, one of the
most respected speaker designers at
JBL, joined Marantz and was given the
charge of developing a speaker line to
complement the company’s other high
end offerings. Superscope built a new
R&D facility for May to work in. The
resulting “HD” speakers were highly
praised and enhanced the brand’s reputation
substantially. Unfortunately, May
died in 1980 and later design efforts
met with considerably less success and
all efforts to design and market loudspeakers
ceased."

That is from audiohistory.com

complete article here: http://www.audiohistory.com/files/documents/marantzhistory.pdf

David

 

[Cogsinister]

Good call cogsinister, apparently there is a connection there.

"In 1976, Edmund (Ed) May, one of the
most respected speaker designers at
JBL, joined Marantz and was given the
charge of developing a speaker line to
complement the company’s other high
end offerings. Superscope built a new
R&D facility for May to work in. The
resulting “HD” speakers were highly
praised and enhanced the brand’s reputation
substantially. Unfortunately, May
died in 1980 and later design efforts
met with considerably less success and
all efforts to design and market loudspeakers
ceased."

That is from audiohistory.com

complete article here: http://www.audiohistory.com/files/documents/marantzhistory.pdf

David

Well there you go.......

 

[Big Tuna]

Yep, there you go. I have great admiration for Mr. May and he has a Son that I believe is continuing his father's work, but I don't know how, what, or where he is. Anyways, David, I got the crossovers out this morning and they are in fact different like yours. I'm sure you could make a matching pair using these parts so I'll send these to you for free. One has inductors that say made in mexico and the other one's say made in USA. They are thousands of numerals apart But either way I am glad to help you to make yours a matching pair crossover-wise. One crossover has a punch hole but the cap that is behind the masonite is not damaged. Couple of the inductors came unglued. I will re-glue them in place so they don't flop around and break the wires. PM me.

Charlie

 

[David57]

Thanks Charlie, PM sent.

Thats interesting that we both have mismatched sets, what are the odds?

I got a bit antsy and ordered Solen caps to do both my crossovers as separate units with different spec's, putting my faith in the original engineering that the sum of the different components would produce the some end result. Its a stretch of my faith, but the best option at that moment. This was before Charlie's offer and if I can make a matching set, that would be all the better.

I hope to have a good stereo and monophonic listening session right before I recap the first speaker. I will try to note any differences between the two speakers (mono) and how they set the sound stage and function as a pair (stereo). I will do this with a couple of chosen tracks, with attention to placement and all settings. Then do a side by side comparison after doing one recap (mono) and a further asessment when both are done (mono & stereo). Then another comparison if I can make a matched set of crossovers. I know, I know, its all so very subjective, but still interesting.

So I need an inexpensive calibrated mic, and some computer software to be more objective? I guess that could be another thread........best I stay away from searching that topic for now, I still haven't introduced my wife to the new to me Yamaha CR-2020. :nono:

David

 

[David57]

The caps have arrived, and here is how they compare to the originals.





The original caps where very close to the inductors, and shared the same application of hot melt glue. I carefully cut a fine kerf between them using a hand held fine tooth hack saw blade, then cut the remainder of glue off bit by bit with a 1/2 inch wood chisel and finally gave them a tap to jog loose the thin layer of glue that was under them.

I also removed the outer terminal strip to make some room, by drilling out two rivets that held it. I will replace this with some single terminals around the perimeter. I will have to stand the two large caps for the bass up on end like the others to make them fit. I will post some picks of this in a later post.

Here is the masonite board with old parts removed. Not a lot of room, but it will do.



David

 

[Cogsinister]

Great job.....keep us updated.......

 

[cooleeo]

Great stuff David, I'll get around to taking some pics of my Hd 660's and posting soon.
My 2250B is in being repaired at the moment and now I am thinking it would be a VERY good idea to get the crossovers recapped. Photos will follow so I can get all the best help and info I will need.

 

[cooleeo]

By the way the serial no.s are only 12 apart (202412 & 202424) so hopefully should be the same. I'm gonna get inside them again tonight and see:yes:

 

[cooleeo]

OK so I couldn't wait until tonight and just had to have a closer look at the crossovers. I didn't want to take them out completely as they seem to be glued to the back of the cabinet as well as screwed in, so the photo's are not the best, sorry. Also if they have already been done then there would be no need:yes: Infact I can now see that some work has been done on them before, and that the parts do not look like they are over 30yrs old. I'v also included some pics of before n after the refoam and of the U/S tweeter that I am STILL waiting for

P.s more pics to follow