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View Full Version : I guess these may be worth refoaming ??



SEAWOLF97
10-05-2006, 03:02 PM
Took a $10 gamble on a beautiful set of Marantz HD 770 's today at GW. Nice condition with decent grills. Looked them up on Fleabay and was SHOCKED ..........

http://cgi.ebay.com/Super-rare-1978-Marantz-HD-770-speakers-near-mint_W0QQitemZ330033888635QQihZ014QQcategoryZ50597 QQrdZ1QQcmdZViewItem

Storm
10-05-2006, 03:06 PM
Wow, what a find!

Good job!

I wish our Goodwill's were that cheap. Down here, they think they are eBay and they ask stupid money for stuff.

:)

mech986
10-05-2006, 03:13 PM
Very Nice!! :applaud: Those should refoam nicely, assuming you can get the correct foams. Let us know if Rick Cobb or others have it.

I always knew Portland has a lot of good vintage gear. I gotta get my brother-in-law who lives near Reed College to get on the ball and go looking. However, he's got a lot more sense than me so he probably won't be able to. :biting:

Let's see those after refoam pictures when you get them done. BTW, don't those cones look a lot like the Decade series or L40 woofers and didn't Bart Locanthi work for Marantz for awhile too?

here's some information I found on the web regarding the connection between Bart Locanthi and Marantz speaker development. Some very interesting stuff on the Flagship Marantz Imperial 9's too.

http://www.audioholics.com/techtips/audioprinciples/loudspeakers/loudspeakersgoodenough1.php

Regards,

Bart

SEAWOLF97
10-05-2006, 08:00 PM
of "Rock Solids" for $5 too.

similars:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260037622660&fromMakeTrack=true

SEAWOLF97
10-06-2006, 11:07 AM
were designed as L100 competitors. Great sound , will be even better with new surrounds. Lable on back shows "33 to 22k +- 3 db" "crossover 750 , 2.3k , 5k"

Orion says "1977-81 , $660 pr. new"

SEAWOLF97
10-08-2006, 09:48 AM
In Portland, there is a great speaker shop - Ja Mac - that does rebuilds and sells foam for about everything. They've got some awesome 30in cones on the museum wall. They mentioned that they always put the foam on the backside, no matter how the original was. Also joked that they put the glue on with a fire hose. :barf:
They took the time to walk me thru the process. Provided shims and glue, and sell quality rings. Good guys. $18 total.
Anyway, the Marantz's came out super. hooked them up and certainly worth my $28 investment.:)

SEAWOLF97
10-08-2006, 11:33 AM
they came out OKAY. could not save the inverted dustcaps, so went with new ones.



Very Nice!! :applaud: Let's see those after refoam pictures when you get them done. BTW, don't those cones look a lot like the Decade series or L40 woofers and didn't Bart Locanthi work for Marantz for awhile too?
Regards,

Bart

mech986
10-08-2006, 02:02 PM
Very Nice Refoaming job. The drivers look like JBL's!! I always liked that Hexagonal Trim ring, just adds a nice touch.

Let's hear about an extended listening session.

Regards,

Bart

SEAWOLF97
10-09-2006, 08:27 PM
Let's hear about an extended listening session.
Regards,
Bart

I keep reading that this model may be an Ed May design
(Unfortunately, Ed would not have the opportunity to develop his concept into a production system. He left JBL in 1976, just as detailed design was just beginning. He joined Marantz Superscope to become their head of loudspeaker design. A custom design facility was built specifically for him. He used it to turn out three complete lines of loudspeakers in very short order. However, this was the last loudspeaker work he would perform. Edmond May passed away suddenly in 1980 while still employed at Marantz.)

http://audioheritage.org/html/people/may.htm

these are VERY smooth. when first fired up, I thot they sounded like the L100s, but after extended listening , I feel the HF is a little better , the LF not quite as authoritative (but barely). The cabinets and grills are good quality.

I set them up in the spot where the L36's were. They are in almost every area, better than the L36, except they are not a cast basket.

The L36s had replaced the AR3s that had replaced the Pioneer CS77a's. Constant upgrades.

I think they are keepers.:)

GordonW
10-12-2006, 01:14 PM
I had a pair of the DS930s, which were functionally the same as the HD770s, but in a more deluxe cabinet (inlaid parquet wood veneer on the tops and bottoms, among other things). I SHOULD NOT have sold them. :( Fantastic speaker. Just plain did EVERYTHING right.

Regards,
Gordon.

GordonW
10-12-2006, 01:17 PM
Just looked at the after-refoam picture :( . Why do people INSIST on changing the dustcap orientation? They're SUPPOSED to be CONCAVE (ie, inward dish). It WILL change the sound of the speaker!

Regards,
Gordon.

SEAWOLF97
10-12-2006, 02:33 PM
Just looked at the after-refoam picture :( . Why do people INSIST on changing the dustcap orientation? They're SUPPOSED to be CONCAVE (ie, inward dish). It WILL change the sound of the speaker!

Regards,
Gordon.

well Gordon, I didnt have a lot of choice. Have only refoamed with the shim method - didnt even know of the "faith method" until 2 days ago. concave caps wernt available, and I dont honestly see how the orientation of "A DUST COVER" can affect sound. I didnt even hear any difference with the Vari-Q plug (or sox) in the port.

Maybe you can enlighten us ??:blink:

edgewound
10-12-2006, 02:55 PM
well Gordon, I didnt have a lot of choice. Have only refoamed with the shim method - didnt even know of the "faith method" until 2 days ago. concave caps wernt available, and I dont honestly see how the orientation of "A DUST COVER" can affect sound. I didnt even hear any difference with the Vari-Q plug (or sox) in the port.

Maybe you can enlighten us ??:blink:

The "concave" dust dome is just turned over.;)

The inverted dome has an effect on dispersion/phase characteristics near the crossover frequency, as well as adding some strength/ stiffness to the cone apex for transients.

There's no such thing as the "faith method" for those of us that are paid to do refoams....It's either a candidate or not.

Shimming is not a 100% guarantee that the voice coil will not rub, but it's a pretty good back-up strategy if it's not cooperating. If it's not cooperating, there'e a good chance the speaker just needs a recone, or possibly refoam and new spider. If the voice coil former is bubbled or otherwise damaged...fuh-gedi-bow-dit...recone/replace. Dynamic centering works nearly 100% of the time for a refoam without disturbing the original cosmetics of the driver.

Your refoam looks pretty good other than not being cosmetically/functionally correct.

The final arbiter here is....you did the work yourself and you're happy with the outcome.

Good job:) :applaud:

GordonW
10-12-2006, 04:01 PM
If you absolutely MUST remove one of those concave dustcaps, the dustcap for a Peavey Black Widow 12" or 15" (commonly known as part # 0288, stamped on the bottom side of the dustcap) can be used as a replacement. You will want to lightly spray the concave side of the cap with flat black paint before installing (if you don't want the number "0288" looking back at you), but it does have a shallow enough dome profile to work. You can either leave it at original diameter (it's 4.5" diameter, where the original Marantz cap is 4"), or you can carefully mark it and cut it with sharp scissors to the right diameter...

Regards,
Gordon.

SEAWOLF97
10-12-2006, 04:04 PM
There's no such thing as the "faith method" for those of us that are paid to do refoams Good job:) :applaud:

I was quoting ROBB3606 "Typically when you do a refoam you take a leap of faith that the foam is the only thing shot and the spider is still in reasonably good condition. If that's true the spider will keep the voice coil centered as long as the cone is not tilted in the gap."

BUT I really do appreciate your input , unfortunately don't know everything yet. Thats why I am on this forum , TO LEARN. No need to reinvent the wheel, when there are experienced, helpful co-enthusiasts who don't mind guiding you.:)

SEAWOLF97
10-13-2006, 12:43 PM
I had a pair of the DS930s, which were functionally the same as the HD770s, I SHOULD NOT have sold them. :( Fantastic speaker. Just plain did EVERYTHING right.
Regards,
Gordon.

The OL went shopping today, and I had a chance to "play" them. Geeze they ARE nice and do everything well even with the degraded dust caps.:eek:
What would the functional equivalent in the JBL lineup be ??:confused:
I do intent to keep them as rears to the 4410's, they add a little more bottom end to the total setup, and very nice HF

maggnepan
10-18-2006, 05:47 PM
Tom, if they are not JBLs it does not matter. They are not keepersl, they are only frog bait to feed your JBL habits. PPPPPPLLLLLease do not lose the faith and fall to the allure of strange women from far off lands. I mean speakers of course.
I too have lots of other speakers, but I never refer to them a s keepers, only waiting to be traded or sold to upgrade my jbl collection. some of them are really quite nice, such as my maggneplaners and my infinitys and my yamaha ns 1000s...oh shoot i guess those are keepers after all.......just keep the lot of them i guess.
Havent seen you in a mo but hope to soon, i will call you in the near future if i can, but i have been under the weather lately.

SEAWOLF97
10-18-2006, 06:51 PM
Tom, if they are not JBLs it does not matter. They are not keepersl, they are only frog bait to feed your JBL habits. .


Dude ...I consider them honorary JBLs

WARNING: HERESY FOLLOWS !!!:duck:

They are superior to the L36s, but I feel the L26s are superior to the L36s too.

GordonW
10-20-2006, 04:12 PM
Dude ...I consider them honorary JBLs




WARNING: HERESY FOLLOWS !!!:duck:

They are superior to the L36s, but I feel the L26s are superior to the L36s too.

Heresy my a**. I agree with that statement wholeheartedly. Both parts, in fact. :D

Given their heritage (coming from the mind of Ed May) I'd say the HD770s deserve honorary status here, at least in one of the back rows of the clubhouse!

Regards,
Gordon.

SEAWOLF97
10-20-2006, 06:06 PM
PPPPPPLLLLLease do not lose the faith and fall to the allure of strange women from far off lands. .

Hey Dangerous Dan .....you are about 35 years too late on that advise (she's about as strange and from as far off as you can get), but at least after a period ( about 2 days ) she accepts new audio gear
( I tell her "I've always had it , I just took it out of storage" ) ...works most of the time.:) :) :) :barf:

Rudy Kleimann
10-21-2006, 09:38 AM
I tell her "I've always had it , I just took it out of storage"

:rotfl: :rotfl: :rotfl: :D :D :D