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L1590's! Now what?


DavidDru

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I was fortunate enough to acquire a nice pair of L1590's this weekend. I will be picking them up over in Oregon later this week. They are the fused original series.

Of course the wonderful thread by TT on the 1590's and it's siblings is a wonderful source of info and good read for background info on what I have here.

What else might I need to know about these?

Currently I have an Adcom GFA5500 amp that I use for other demanding speakers including the AR3's, Infinity RSII's, and Apogees and it seems to run those admirably. Will it be enough for the L1590's? I can't bridge it but should I look into bi-amping eventually?

For now, my main listening lounge is not big so I don't need to move a lot of air for things to get loud.

Does anybody have a copy of the Series 1 manual?

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Beautiful speakers!

Please tell me you didnt score them for $10 like everyone else seems to... haha

It may be worth it to ship the mids (and tweeters)? to the guy in AZ that restores them and freshens up the ferrofluid. People are starting to complain that it has been muddying up the mids at this point.

I cant imagine your current amp being underpowered for them...

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Well, picked them up yesterday and have them hooked up now. Very, Very Nice as others have said here (TT) Impressive. I am running them with my Adcom GFA5500 and a tube preamp. My room is on the smaller side so I think that will be plenty.

Bassment, I didn't get them for that little, but not too bad at $300. While in Bend I did stumble upon another pair of speakers that I ended up bringing home for a mere $100. The don't belong in this forum though as they start with A and end in 9. :ph34r:

All drivers seem to be in good order but would like everyone's impression on weather or not I should send the tweeter/mids down to Arizona to be looked at and serviced. You can see a slight impression in one of the woofer dust caps too.

The cabs will need some TLC, but nothing that scares me. The right one in the photo has the unfortunate dark water stain that will be the most challenging thing to deal with.

Most of the cabinet scratches are related to previous owner struggling with the grills and worn out or broken pegs as seen in the last photo. The grilles are okay but on the verge of becoming an issue so I need to get them under control.

Anybody know if I will be able to find the grill pegs and receivers for these somewhere so I can replace these?

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I have used Monacor branded grill pegs and receivers... they do sell at least two different sizes. I gues there must be someone in US selling these too.

Best Regards

Kimmo

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I contacted ADS repair guru Richard So down in AZ. He think these would benefit from service to the Mids and Tweeters. Old Fero Fluid gets muddy I guess. Something you probably wouldn't realize until they are serviced and get them back and hear a difference. He has a special for all 4 for $225 that I will probably take advantage of.

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Well, picked them up yesterday and have them hooked up now. Very, Very Nice as others have said here (TT) Impressive. I am running them with my Adcom GFA5500 and a tube preamp. My room is on the smaller side so I think that will be plenty.

Bassment, I didn't get them for that little, but not too bad at $300. While in Bend I did stumble upon another pair of speakers that I ended up bringing home for a mere $100. The don't belong in this forum though as they start with A and end in 9. :ph34r:

All drivers seem to be in good order but would like everyone's impression on weather or not I should send the tweeter/mids down to Arizona to be looked at and serviced. You can see a slight impression in one of the woofer dust caps too.

The cabs will need some TLC, but nothing that scares me. The right one in the photo has the unfortunate dark water stain that will be the most challenging thing to deal with.

Most of the cabinet scratches are related to previous owner struggling with the grills and worn out or broken pegs as seen in the last photo. The grilles are okay but on the verge of becoming an issue so I need to get them under control.

Anybody know if I will be able to find the grill pegs and receivers for these somewhere so I can replace these?

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DavidDru,

That Ferrofluid issue has become a topic of a lot of discussion. If the fluid dries up, the midrange and tweeter would likely sound distorted and "muddy," and the high-frequency mid-range and treble response would fall off precipitously. But on the other hand, if you think the sound is clean without distortion, there's a good chance the Ferrofluid hasn't dried up. I have both L1290s and L1590s, and I don't detect any distortion or change in the character of the sound, but I would have to say that neither pair of ADS speakers was electrically abused (over-driven) over time, so I don't suspect any real issue with the tweeters (or the crossovers, for that matter). In short, I don't detect too much difference from when they were new, but hearing memory is short, so it's not possible to know precisely. If you are a risk-taker, you can remove a mid-range driver and a tweeter, and you can actually remove the aluminum top plate and inspect the gap and the voice coil to see if the material has dried. The dome and coil assembly can be re-installed, but it is still a slightly risky proposition.

The only real test would be to measure the tweeters' response anechoically, and that would not be easy to do without taking the drivers out of the cabinet and measuring them -- with crossover in place -- individually for on-axis frequency response to see if they match the original measurements (only a few response graphs are present in some of ADSs original lliterature). On the other hand, sending them off to be "checked" for that would mean that a new dome/coil assembly would have to be installed, and the old magnet assembly/gap would have to be completely cleaned out and replaced with fresh Ferrofluid, and that is a very, very difficult thing to do since the Ferrrofluid is a magnetic substance in an oil base, and those magnets are very powerful. In other words, unless it was done by the factory -- which no longer exists -- it's very likely that the end result could be worse than when you sent them in for repair. As they say, "if they ain't broke, don't fix them!"

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One question for you: who is that in your avatar picture!

--Tom Tyson

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Ferrofluid does also reduce Q of resonance. Measuring Q or at least max impedance will take only few minutes and may give clue how things are?

This is not fool proof method as coil scraping to dried fluid will also reduce Q,

Best Regards

Kimmo

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That's my wife.

Thanks for the feedback gentlemen. The only reason I would send these in for refurbishment would be to do it now before it became an issue. Richard So performed those duties at ADS back in the day so this is the closest thing to the real deal I guess. I will ask him if the process in any way can result in reduced performance. The dome on one of the mids has a dent in it and it would be nice to get that straightened out if possible in the servicing.

Like I said before, really the only pressing issue is the grilles. Followed by the cabinets and getting them shining once again. I do see more amp in my future, especially now that the AR9's are also in the stable.

Tom, that's actually actress Isla Fisher in my Avatar. ;)

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Ferrofluid does also reduce Q of resonance. Measuring Q or at least max impedance will take only few minutes and may give clue how things are?

This is not fool proof method as coil scraping to dried fluid will also reduce Q,

Best Regards

Kimmo

Kimmo,

Yes, measuring the impedance at resonance might be good, but it would need to be compared with the original factory curve for reference to determine any changes. Does anyone have that? I suspect not, insofar as specific measurements were proprietary during the ADS production years, to my knowledge. There were generic measurements that were published, but not specific measurement curves. It's the same with the frequency-response measurement of an original vs. an old one; unlike AR, for example, there were few, if any, published response and distortion curves, per se, of the ADS drivers other than in promotional literature.

Probably the only thing to do now would be to listen carefully to determine if there is an audible problem. If one of the speakers had been previously played at very high output levels -- especially over extended periods -- the temperature of the voice coil would be very high, and this would accelerate changes to the Ferrofluid in the gap (even cause the magnetic fluid to boil), but under normal conditions, no one seems to know how long the Ferrofluid will remain in the gap without going bad. I've heard 15 years, but that's also the "half-life" of urethane-polymer foam surrounds, so that age period for Ferrofluid is probably internet "conjecture."

I honestly don't know the answer to "how long." It is clear, of course, that if new oil is put in the gap, the old stuff has to be removed, and that job is very difficult due to do because of the strong magnetic strength of the ADS magnets and the narrow voice-coil gap. Metal particles would be left behind, too. I suspect that those magnetic particles and any oil residue left would be highly resistant to removal, so I just don't know how it could be effectively accomplished. It's not possible to get beneath the gap; i.e., on the underside, because of the back plate/pole piece assembly that are staked together. Therefore, all removal would have to be done from the top, and I've seen attempts at doing this, but none was definitive and the outcome was questionable.

And, once all of this was done, the driver would have to be measured for smoothness, uniformity and impedance, as well as for sensitivity.

—Tom

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  • 4 weeks later...

That's my wife.

Thanks for the feedback gentlemen. The only reason I would send these in for refurbishment would be to do it now before it became an issue. Richard So performed those duties at ADS back in the day so this is the closest thing to the real deal I guess. I will ask him if the process in any way can result in reduced performance. The dome on one of the mids has a dent in it and it would be nice to get that straightened out if possible in the servicing.

Like I said before, really the only pressing issue is the grilles. Followed by the cabinets and getting them shining once again. I do see more amp in my future, especially now that the AR9's are also in the stable.

Tom, that's actually actress Isla Fisher in my Avatar. ;)

No complaints about the sound of the 980's here using the same drivers. The tweeters were pulls from another set but I managed to find one that appeared to be NIB where it is still sitting.

Is it really that hard to replace ferrofluid? Sounds like solvent flush, brush and blowout with compressed air to me. Maybe not ;)

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No complaints about the sound of the 980's here using the same drivers. The tweeters were pulls from another set but I managed to find one that appeared to be NIB where it is still sitting.

Is it really that hard to replace ferrofluid? Sounds like solvent flush, brush and blowout with compressed air to me. Maybe not ;)

No complaints about the sound of the 980's here using the same drivers. The tweeters were pulls from another set but I managed to find one that appeared to be NIB where it is still sitting.

Is it really that hard to replace ferrofluid? Sounds like solvent flush, brush and blowout with compressed air to me. Maybe not ;)

Owlspace, perhaps you are visualizing the drivers as "straight-through" voice-coil gaps, open on the back, thereby enabling you "apply some solvent with a brush and blow out the residue on the other side." Bingo, job done, but the problem is that the magnet assembly's bottom plate and pole piece are staked together and attached to the powerful ferrite magnet with epoxy and mangetic force; but not only that, the metal particles will cling like crazy to the magnetic surfaces, and unlike dirt or dust particles, they will try to move around in a circle before they come out of the gap. Unfortunately, there is no way to remove the "back" of the driver, either the midrange or tweeter. So now you take compressed air and blow the metal particles down into the magnet assembly, causing them to cling to the magnet itself or on the bottom of the gap. Most likely this would be the end of this driver.

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This is the reason that you see repair done to voice-coil gaps with pieces of masking tape and not compressed air. Nevertheless, this is only part of the problem: when you go to replace the old Ferrofluid (if successful doing it), you must then know how much -- and at what viscosity -- new fluid to add to the gap. The proper amount determines the performance of the driver to a large extent. Who has that spec? Who has the original driver response graphs, etc.

Just about anyone could get a mid-range driver or tweeter to "function" again, but to get it to sound right is another thing altogether. Most speaker-repair outfits steer clear of repairing tweeters for this reason.

--Tom Tyson

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Thanks, Tom. I am not in a hurry to recharge any ferro-fluid tweeters given all the variables ... besides at my age hearing is more of an issue than tweeter roll-off. Audible distortion would be another matter.

I am assuming by your description that the ferro-fluid is viscous enough to remain only in the area of the voice coil under normal operating conditions, but if subjected to excessive operating temperatures it would flow to the lower half or bottom of the gap and perhaps become even more viscous in the process. I expect this would lead to some audible distortion.

Roger

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Thanks, Tom. I am not in a hurry to recharge any ferro-fluid tweeters given all the variables ... besides at my age hearing is more of an issue than tweeter roll-off. Audible distortion would be another matter.

I am assuming by your description that the ferro-fluid is viscous enough to remain only in the area of the voice coil under normal operating conditions, but if subjected to excessive operating temperatures it would flow to the lower half or bottom of the gap and perhaps become even more viscous in the process. I expect this would lead to some audible distortion.

Roger

Owlsplace, (notice that I spelled "Owlsplace" correctly this time, sorry about that before!), when the Ferrofluid oil is mixed together, the tiny metal particles -- like a metal dust -- are evenly dispersed throughout the special, high-dollar synthetic-oil solution. The particles are fine enough that they stay mixed in the solution like the pigments in a tube of oil paints, and once in the magnetic gap, the solution is then strongly attracted to the magnet pole pieces (this being the center pole piece and the top-plate structure forming the "gap"), thus conducting a great deal of the heat that can develop in the voice coil and distributing this heat onto the actual magnetic structure itself (the pole pieces). It is the strong magnetic lines-of-force across the north-south gap that hold the solution precisely in the gap without allowing it sag down by gravity or to drain off. Some drivers have the FF solution on only one side of the gap, and it never migrates to the other side. Others have the solution on both sides of the gap.

The oil can eventually evaporate, of course, but it is a very special synthetic oil (and the good stuff is extremely expensive) and will supposedly last a very long time, except in cases of abusively high amplifier input levels for extended periods of time. I understand that this can cause accelerated evaporation or "boiling" of the FF because of the excessive thermal build-up.

—Tom Tyson

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  • 1 month later...
  • 4 months later...
On December 12, 2015 at 11:59 PM, tysontom said:

Owlsplace, (notice that I spelled "Owlsplace" correctly this time, sorry about that before!), when the Ferrofluid oil is mixed together, the tiny metal particles -- like a metal dust -- are evenly dispersed throughout the special, high-dollar synthetic-oil solution. The particles are fine enough that they stay mixed in the solution like the pigments in a tube of oil paints, and once in the magnetic gap, the solution is then strongly attracted to the magnet pole pieces (this being the center pole piece and the top-plate structure forming the "gap"), thus conducting a great deal of the heat that can develop in the voice coil and distributing this heat onto the actual magnetic structure itself (the pole pieces). It is the strong magnetic lines-of-force across the north-south gap that hold the solution precisely in the gap without allowing it sag down by gravity or to drain off. Some drivers have the FF solution on only one side of the gap, and it never migrates to the other side. Others have the solution on both sides of the gap.

The oil can eventually evaporate, of course, but it is a very special synthetic oil (and the good stuff is extremely expensive) and will supposedly last a very long time, except in cases of abusively high amplifier input levels for extended periods of time. I understand that this can cause accelerated evaporation or "boiling" of the FF because of the excessive thermal build-up.

—Tom Tyson

Tom,

This is a great description of FF and how it works. What a brilliant concept and invention.

Thankyou!

Glenn

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  • 2 months later...

Just received my mids and tweets back from Richard So that did his magic on them.  Ummm, WOW!

Yes the L1590 is a fantastic speaker...at all volumes.  They seem to do pretty good in what is probably a room too small for them by specification, but even so, they might be my favorite speaker in the house right now.  Running them with my single Phase Linear WOPL 400.

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3 hours ago, DavidDru said:

Just received my mids and tweets back from Richard So that did his magic on them.  Ummm, WOW!

Yes the L1590 is a fantastic speaker...at all volumes.  They seem to do pretty good in what is probably a room too small for them by specification, but even so, they might be my favorite speaker in the house right now.  Running them with my single Phase Linear WOPL 400.

Good to hear :D

Roger

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  • 1 month later...

Now that you have had some time with the rebuilt drivers can you talk about what differences you remember from those old tired drivers?

 

Additionally, you have the 910 and the 1590, can you talk to the differences in these speakers?  

 

I have the 710 and 1590/2 (picked up about 2 weeks after you got yours last year).  They are on different floors and really the 710 isn't the kind of speaker I have in the main rig most of the time.  We did use them to compare amp a number of years ago.  They did a fine job in that capacity.

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Hey 899.  I now also have L710's so interestingly enough I started a thread over at AK simply to post a line-up photo of all 3 models so folks can get a feel for scale on them.

Since you have the 1590/2's and the 710's you will probably agree that the biggest difference is of course the much bigger presence of the 1590's.  All 3 models have fairly similar highs and mids but each differ significantly in the lows.  Much of this may be room dependent as I am learning.  My current favorite are the L1590's.  With their larger baffle I think the 910's are more dependent on scale of room.  Or I need to help them out in my 12x12 listening lounge with more room treatments as the bass can be overpowering at times and needs some control.  

It is kinda hard to go from the larger 2 models down to the 710 because you instantly lose the bottom end.  Not that they are lacking on their own right, just that in comparison they are in a different class in that regards.  But we all know bass is like sugar and sometimes less is more.

I did not notice a big difference with the drivers after servicing by So.  I wasn't necessarily concerned with them prior, but of course did not know if what I was hearing was what i should.  I mainly sent them in to get them in shape for the future before that service is no longer available.  Also by now, I probably can't recall what they sounded like prior.  I will send the 910's drivers in in the near future.  Stands first.  Glenn also had his 910 drivers serviced and did notice a little improvement in the sound Q he has been stating (correct me otherwise Glenn).  A bunch of guys have been sending their drivers in to So lately - at least it seems like it reading things over at AK - and several noticed big improvements.  most of those had apparent issues though with "muddiness" and lack of sparkle prior.

I replaced the woofer cap on eh 910's and completely refinished the cabs, cleaned up and tightened the other pieces and parts on the crossovers and added a new set of binding posts for easier connecting and disconnecting.  Making stands and in need of badges.

 

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Hi David,

Yes, there was improvement after Richards rebuild, nut not a night & day difference with my drivers. They sounded great prior to the rebuild, but the domes were covered with cat hair from the PO's cats. Didn't effect the sound. I was interested in preservation mostly. I know they will sound great for the next 30 years now.

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