JBL Concert Speakers: power & Connections?

[kyrvas]

No.

I can tell you since both channels are dead it is not getting power. Otherwise you would have to entertain a fault in both channels. The power supply was quite complex and the protection advanced for its date. The output transistors are direct coupled which is unusual for receivers of that date. Since the output stage is direct coupled, protection needs to be robust, or the shorted transistor blows up the speakers, which at that time was a common occurrence.

After looking at the service manual something is shorted, and the most likely cause is a power transistor or power transistors.

Do not take that unit to a recycling center. Because of its age, the ethical thing to do is to make it available to an enthusiast restorer via eBay.

"Since the output stage is direct coupled, protection needs to be robust . . . most likely cause is a power transistor" - Sounds logical based on the symptoms.

"Do not take that unit to a recycling center." Please explain.

 

[TLS Guy]

TLS Guy - this is more good info; I like being educated.

Yes, I naively I do think they are worth more. But a high price is not my main reason for selling.

JBL concert-style speakers: "seldom would a speaker like that be much good" but if they sound good (relative to the listener and the environment) and can project sound for a family outdoor gathering, or party, there may be an interested buyer(s). Please define "over ported". BTW, I only took a photo of one speaker cabinet; there are others with a JBL logo in the lower corner.

Marantz on eBay: wouldn't pursue that since they are heavy to ship, but maybe I can contact a local restorer.

"a package deal . . . Disco": that's a really good thought; which would help us (my wife's in this also) move this equipment.

The BGW amp: "$150 to $175" sounds reasonable.

Mixers: my BIL was using the Mackie Onyx1620 at his work station before he was hospitalized.
I have no clue how to test for a noisy Fader.

"sell it as a package may be $750 to $850" - another good sound to me.

"part out the speakers": OH boy, although I know how to use a screwdriver, there are other things for me to pursue at this stage of life. The right person at the right time could possibly benefit form these. Your advice to sell as a package is definitely worth pursuing.

Thank you very much for taking all this time on my project.

So the speakers are not the same? If you can send pictures and model numbers that would be great.

I looked on line at JBL pro speakers of that era and found nothing like the one in the photograph.

Also JBL speakers of that date and using similar sized woofers had one or two ports of that size, generally one. It just looks to me as if there is far too much port area.

I don't want to get into mixers with you. You just to not have enough experience, so sell as is.

 

[TLS Guy]

"Since the output stage is direct coupled, protection needs to be robust . . . most likely cause is a power transistor" - Sounds logical based on the symptoms.

"Do not take that unit to a recycling center." Please explain.

You would not put a vintage car through the crusher, would you?

 

[kyrvas]

So the speakers are not the same? If you can send pictures and model numbers that would be great.

I looked on line at JBL pro speakers of that era and found nothing like the one in the photograph.

Also JBL speakers of that date and using similar sized woofers had one or two ports of that size, generally one. It just looks to me as if there is far too much port area.

I don't want to get into mixers with you. You just to not have enough experience, so sell as is.

Looking through the cabinet screens, the drivers appear to be the same, at least in size and coloration. As mentioned in the early postings, the only driver with a visible model number is the JBL 2370A horn, found topmost in each of the four. lovinthehd, early on asked me to open the cabinets and pull the drivers to look for numbers; I really don't want to get this deep into them if I don't have to. Here are some images:

 

[kyrvas]

You would not put a vintage car through the crusher, would you?

I hear what you are saying.

 

[kyrvas]

SUCCESS (partially)! Hooked the JVC KD-V6 Stereo Cassette Deck to the BGW 210 amp, and slowly turned up the deck's Output, and what do you know - music to my ears. Unfortunately, the 30 watt Portable Sonocasters' sound awful; they buzz. Nonetheless, tomorrow I go to storage and will connect a pair at a time of the JBLs to the BGW amp. The amp can actually take four at a time but I only have the cabling for two; the other speaker wire has 1/4" connectors.

 

[lovinthehd]

You would not put a vintage car through the crusher, would you?

Don't think I'd put the 2270 in the same class as a vintage car worthy of restoration....but keeping stuff out of the garbage pile if someone can repair it and sell it to a hipster I guess is still worthy of the effort of getting it to that person.....

 

[TLS Guy]

Don't think I'd put the 2270 in the same class as a vintage car worthy of restoration....but keeping stuff out of the garbage pile if someone can repair it and sell it to a hipster I guess is still worthy of the effort of getting it to that person.....

Depends on the beholder. I ran into a guy who was a USAF electronics tech, and he has a passion for restoring old receivers, especially Marantz. Seems he has a boat load of them and can never bring himself to part with them.

By the way some old cars are junk and always were, but they always get a following.

Looking through the cabinet screens, the drivers appear to be the same, at least in size and coloration. As mentioned in the early postings, the only driver with a visible model number is the JBL 2370A horn, found topmost in each of the four. lovinthehd, early on asked me to open the cabinets and pull the drivers to look for numbers; I really don't want to get this deep into them if I don't have to. Here are some images:

View attachment 21328

View attachment 21329

View attachment 21330

I'm sure those are not JBL speakers. They are speakers built with JBL parts.

They will make noise for sure. But you will have to decide if it is music.

 

[sterling shoote]

Marantz 2270 was perhaps Marantz's highlight. It came around at about the same time as the JBL L100. I'd see many of these outfits during the period. With maybe something like a Dual 1229, the Stones sounded really great. I sold mine, a big mistake. I thought the Marantz separates at the time would be better, like the Marantz 3800 control amp. Not so. It had a low level hum which, two times back to Marantz, they could not repair.

 

[lovinthehd]

Can't remember for sure which one I had, can't find my old receipt that I did have at one point, think it was indeed the 2270, looks right, date seems right. Don't remember it being all that marvelous, seem to remember it bled radio over to other inputs faintly (with nothing playing on that input, volume up). I did have Advent speakers and a Dual player, tho

 

[kyrvas]

Depends on the beholder. I ran into a guy who was a USAF electronics tech, and he has a passion for restoring old receivers, especially Marantz. Seems he has a boat load of them and can never bring himself to part with them.

By the way some old cars are junk and always were, but they always get a following.


I'm sure those are not JBL speakers. They are speakers built with JBL parts.

They will make noise for sure. But you will have to decide if it is music.

TLS Guy - I'll probably never know if the midrange and the woofer are JBL but the 2370A horn is even labeled JBL.

 

[lovinthehd]

TLS Guy - I'll probably never know if the midrange and the woofer are JBL but the 2370A horn is even labeled JBL.

The drivers may be JBL, but that doesn't mean the speaker cabinets or crossovers are (designed and built by) JBL...one way to find out, tho.

 

[kyrvas]

Marantz 2270 was perhaps Marantz's highlight. It came around at about the same time as the JBL L100. I'd see many of these outfits during the period. With maybe something like a Dual 1229, the Stones sounded really great. I sold mine, a big mistake. I thought the Marantz separates at the time would be better, like the Marantz 3800 control amp. Not so. It had a low level hum which, two times back to Marantz, they could not repair.

Sterling - I now have one Marantz 2270, bequethed to me, that because of the help I've gotten on this forum in prodding it along; and coming to appreciate its solid controls and beautiful lighted display, I would like to keep it if the repair would not be costly. . . . I was just minding my own business and now I'm on an audio forum; "Man plans his path but God directs his steps."

 

[kyrvas]

The drivers may be JBL, but that doesn't mean the speaker cabinets or crossovers are (designed and built by) JBL...one way to find out, tho.

Oh no . . . Do you mean get the screw driver out?

 

[kyrvas]

Had a good day today after a thread of 90 posts, this audiophyte (did I really say audio?), plugged in four (suspect) JBL concert speakers to a BGW amp with an audio source of JVC KD-V6 playing orchestral music (Christmas no less; didn't have time for the "101 Strings" cassette). Yes, I heard music: beautiful, bold, and loud (6 on the Output Control; did not want to disturb the neighbors by turning it higher).

Next, need to prepare another pair of cables; not sure what gauge I have; they are the common brown, flat 2-wire but don't see an awg imprint on them.

Then, pricing?

 

[kyrvas]

To all who helped get me to this place in my audio component education, THANK YOU VERY MUCH! Especially, lovinthehd, and TLS Guy for all your insightful feedback and research. This is truly a professional forum, helping beginners like myself. It's clear that each of you love the world of audio.

There are still smaller single components which need identifying and testing, such as Parasound Equalizer, Micro Diamond Dissolve, Denon Magnetophone, etc but the big footprint driver cabinets were the items needing to move along first.

Again, thank you for your consistently professional help.
-bob-

 

[lovinthehd]

Is the Denon Magnetophone a cassette deck like this? http://www.ant-audio.co.uk/Tape_Recording/Service/Denon_DRM44HX_DRM33HX_User_Manual.pdf

I'd not heard that term before, and didn't expect a tape deck when I looked it up.

ps You're welcome and glad you are making progress...

 

[TLS Guy]

Is the Denon Magnetophone a cassette deck like this? http://www.ant-audio.co.uk/Tape_Recording/Service/Denon_DRM44HX_DRM33HX_User_Manual.pdf

I'd not heard that term before, and didn't expect a tape deck when I looked it up.

ps You're welcome and glad you are making progress...

Magnetophonis German for tape recorder.

 

[lovinthehd]

Magnetophonis German for tape recorder.

Apparently in the manner that Kleenex is toilet tissue; tonbondgerat is what I find in the dictionary. German brand name of AEG originally it seems. https://en.wikipedia.org/wiki/Magnetophon

 

[kyrvas]

Is the Denon Magnetophone a cassette deck like this? http://www.ant-audio.co.uk/Tape_Recording/Service/Denon_DRM44HX_DRM33HX_User_Manual.pdf

I'd not heard that term before, and didn't expect a tape deck when I looked it up.

ps You're welcome and glad you are making progress...

Yes, lovinthehd - now I get it; I was reading one side of the box which is probably not English, just appeared close. It is actually, DENON DRM-700A STEREO CASSETTE TAPE DECK; haven't gotten it out of the box yet; hope it is not another repeat of the Marantz rcvr; looks good but doesn't work in one important way.