ads L780's

[soundmotor]

I’m basing it on some research I did a few years ago. I bough my L-780s on ebay. The glue that was supposed to hold the butyl surrounds down to the basket, had corroded the lip of the steel baskets to the point the surrounds separated from the baskets. (Almost all the L-780IIs or L-590IIs I see on Ebay have some degree of the corrosion.)

Looking for information, I found that the woofers on the series I were 206-0324 and the series II have 206-0355. I haven’t seen the 0324s myself but I was under the impression they have cast baskets while the 0355s have stamped steel baskets. I also don’t think the 0324 are likely to get the glue corrosion that are the curse of the 0355s. As far as the sound quality goes, I haven’t heard the series I but I like my series IIs but they don’t sound as good as my L880s.

- Pete

The corrosion issue is odd and I don't have a conclusive answer as to why nearly all of the later ones can have it to some degree. When I say later, it is nearly all pincushion style steel basket speakers, not just the ones in the 780. The last generation round steel baskets don't seem to do this. I've seen it on early vintage ones too, but not with any prevalence. I suspect that the glue formulation was changed somewhere along the way. I've never seen the surrounds lifting on the cast basket models although, glue can certainly break down and be improperly applied.

All 780's used stamped steel baskets. The early versions did not use cast. When you moved up in the line to the 880 series & towers, you got cast ones. I don't believe that 206-0324 is the correct part number. Pretty sure that number was for the 10" used in the PB1500 subwoofer cabinet. 206-0354 rings a bell but that is a shot in the dark.

The major changes across the board from Series I to Series II was the protection scheme in the crossover, from fuses to polyswitches. Sometimes some minor tweaking in the crossover values too. When ADS changed the part number of a woofer that was virtually identical to its predecessor, it usually signified a cosmetic or production process change to a functionally identical part. Easiest to see that on was the tweeters & mids. Sometimes there were drive system improvements such as changing the voice-coil former to Kapton from aluminum. That gave them better durability in an abuse or overdrive situation.

Lastly, polyswitches are a mixed bag. Many hate what they do to the "sound". You can make the argument that anything will sound better with fewer parts in series with the drive units. Perhaps some of your concerns on sound quality relate to that?

 

[LBPete]

I'm not familure with "polyswitches." Are they some kind of resetable fuse? If they affect the sound quality can they be removed and replaced with fuses?

- Pete

 

[mhardy6647]

Yeah the Raychem "polyswitch" is some sort of self-resetting fuse gizmo. PartsExpress, Mouser, Digikey sell 'em (or at least they did). They were considered to be just short of the Antichrist when Klipsch started using them in their Heritage speaker crossovers (IIRC).

 

[soundmotor]

Yeah the Raychem "polyswitch" is some sort of self-resetting fuse gizmo. PartsExpress, Mouser, Digikey sell 'em (or at least they did). They were considered to be just short of the Antichrist when Klipsch started using them in their Heritage speaker crossovers (IIRC).

The way they work is pretty neat. When the current going through them is low, they have milliohm resistance. When the current goes up, they heat up and the resistance goes into the megohm range essentially shutting off the the driver they are attached to. These are called positive temp coefficient (PTC) polyswitches. To reset them, you turn down the volume and in 30 seconds or so, they reset. If you shut off the system it takes half an hour or more to get them to. "Solid-State Tweeter Protection"; you know what you are dealing with. If you bypass them, in general you need to add series resistance to offset them. 0.3 ohms is the approximation.

Inrush current limiters (like you'll find on an SS receiver) work exactly the opposite and are called negative temp coefficient (NTC). When they get hot their resistance goes down. Polyswitches are essentially a solid-state device.

 

[LBPete]

Now I see what the fuss is about. I suppose they could fail in a way that would add some unknown amount of resistance in the circuit. That would affect the sound quality.

- Pete

 

[Fomoco1649]

I’m basing it on some research I did a few years ago. I bough my L-780s on ebay. The glue that was supposed to hold the butyl surrounds down to the basket, had corroded the lip of the steel baskets to the point the surrounds separated from the baskets. (Almost all the L-780IIs or L-590IIs I see on Ebay have some degree of the corrosion.)

Looking for information, I found that the woofers on the series I were 206-0324 and the series II have 206-0355. I haven’t seen the 0324s myself but I was under the impression they have cast baskets while the 0355s have stamped steel baskets. I also don’t think the 0324 are likely to get the glue corrosion that are the curse of the 0355s. As far as the sound quality goes, I haven’t heard the series I but I like my series IIs but they don’t sound as good as my L880s.

- Pete

I just bought a clean set of L 780s/ V1 and as said nice quality woofers with zero corrosion on baskets

 

[LBPete]

They are very nice speakers, enjoy! This thread is 18 years old. It's a trip down memory lane. I no longer have the L-780s. I gave them to a brother in law years ago.

- Pete

 

[Fomoco1649]

Ok...thanks Pete

 

[Blue Shadow]

This thread is 18 years old.

Yes, old threads bring new additional posts especially when someone finds that item and is thrilled with it and posts in most of the threads about that item. Can bring more new info on the subject item but right now I'm just thinking Fomoco loves his new L780 speakers and wants folks to know. If a pair showed up here at a reasonable price, or 880/980, I'd grab em. Sold my last home ads, the 710s last year. One car is full of the brand so I still have the a/d/s/ sound in my life.

 

[Fomoco1649]

Yes, old threads bring new additional posts especially when someone finds that item and is thrilled with it and posts in most of the threads about that item. Can bring more new info on the subject item but right now I'm just thinking Fomoco loves his new L780 speakers and wants folks to know. If a pair showed up here at a reasonable price, or 880/980, I'd grab em. Sold my last home ads, the 710s last year. One car is full of the brand so I still have the a/d/s/ sound in my life.

Agreed...I will try not to respond to old post AZ ny more...thanks

 

[Blue Shadow]

Agreed...I will try not to respond to old post AZ ny more...thanks

No go ahead and respond, especially if you have a question about that discussion or even better some added info about the discussion. The reason these threads are left open is because we are talking about crap that is 25 years older than the thread anyway. More info the better.

 

[Fomoco1649]

No go ahead and respond, especially if you have a question about that discussion or even better some added info about the discussion. The reason these threads are left open is because we are talking about crap that is 25 years older than the thread anyway. More info the better.

Ok...thanks..really .appreciate all the great AK info , expierience..& members

 

[Blue Shadow]

Agreed...I will try not to respond to old post AZ ny more...thanks

You do know that pricing of used gear can be influenced by ak. We had a era of high ADS prices 15 years ago because folks talked about how good they are. All the 'taxed' brands, selling for more or WAY MORE than comparable gear from other brands are placed on a high pedestal and praised by many here. This has to jack up the prices as folks seek vintage gear because ak is the first and has multiple hits when vintage units are search.

But it is all good.

 

[Fomoco1649]

You do know that pricing of used gear can be influenced by ak. We had a era of high ADS prices 15 years ago because folks talked about how good they are. All the 'taxed' brands, selling for more or WAY MORE than comparable gear from other brands are placed on a high pedestal and praised by many here. This has to jack up the prices as folks seek vintage gear because ak is the first and has multiple hits when vintage units are search.

But it is all good.

Ok...that sounds like the truth....thanks...but it also seems like crazy high prices since Covid?

 

[Fomoco1649]

Good news….I checked my dimpled tweeter this morning, and it decided to pop out on its own & looks perfect….amazing

 

[Dswankey]

Agreed...I will try not to respond to old post AZ ny more...thanks

You just did again today

ADS L710's or ADS L780's

which would you prefer?

www.audiokarma.org

Not to mention posting this same reply in a different thread

ADS L-780/2 – This Year’s Out-of-Control Project – A Photo Journey

I recently picked up a pair of L-780/2 that need a little TLC... this old Porkloin thread is inspirational. Porkloin was a good guy. I miss him. We lived in the same neighborhood until I moved away a few years ago. Now he's RIP. John

www.audiokarma.org

Good news….I checked my dimpled tweeter this morning, and it decided to pop out on its own & looks perfect….amazing

You're posting to all of these ADS threads that you don't even remember where you're posting to.

I'm assuming the above post was meant for this thread

Question about Soft Domes and dents, ADS among others

I have some ADS in the corral. Fortunately all of the domes are clean and dimple free. I am considering a couple new additions and one of the potential issues is that there is a dimple in each of two midrange drivers. I haven't really any idea how the dome works, but I would think they...

www.audiokarma.org