Apogee Duetta Signature Rebuild

[Brad225]

Busted watching video but not out of the game

Here's some help, a series of re-ribbon videos for Calipers: https://www.youtube.com/user/minsky57/videos?flow=grid&view=0.

Recommend you do all the work apart from the re-ribboning, as you may find it difficult to get bass panels anyway. Graz isn't keen on anyone doing that by themselves due to so much trouble in the early days. Basically supplying bass ribbons to clueless people who thought they could do it turned out to be more trouble than it was worth.

I can see how people could get into trouble with the bass ribbons though I think with some patience, making the proper jigs and proper work area set up I would give it a try. Though there is much more I need to learn before making the commitment.


Now as for step #1 of making the commitment and WAF.

I was sitting in our office last night watching the videos you had posted the link to. I think I was up to video #5 before my wife stopped on her way back from the copier and asked what I was watching.

So, I figured I may as well throw it out and see if I end up with any black and blue marks. I said, "I'm watching some videos on how to rebuild the next set of speakers I want to buy." Trying not to look scared.

She stared at me for a moment with what I am sure was a thought like "Over my dead body your getting and rebuilding more speakers right now ". But only said "You do remember you have a list of things to finish on the house?

To which I said " I would only start looking to purchase a pair in bad shape I can rebuild later".

With no descent to that comment, I believe the male interpretation of that would to be "Sure honey, if that is what you want to do, just get your other work done first".

What do you think, isn't that sort of what she said? I promise I won't bring up any of your names at the divorce proceedings.

 

[Bernard]

Brad, don't forget that that list could grow.....and grow...until being like Justin is but a pipe dream.

And yes, my interpretation of female speech is the same as yours.

 

[User211]

+1 with Bernard's interpretation.

Bass panels though - self-installation would be OK if you can talk Graz into selling you some. If, and I say IF he will (I suggest you how him your CLS thread during the proceedings), don't blame me if it doesn't go well. I did warn you

Those videos were on a CD supplied with the bass panels to self-installers years ago. I dunno who that is (it isn't Graz) BTW. Don't forget that the design allows you to do something ML can't - provide you with enough force to drive a panel down to genuine LF without messing around with dynamic driver integration. It won't go huge sub low, but it does go low. It is also amazingly resolute and expressive in a way dynamic driver bass isn't. That's one of the major rewards that'll make it all worthwhile

If you have a go, remember the old Apogee forum (not the current one) archives are FULL of info. if you can find it!

And, of course, if you do have a go, let us all know

 

[Brad225]

Well I guess some day came a bit sooner than I first thought but the condition what I was looking for. I found a pair of Divas with one damaged and one dented bass foil/ribbon and passive crossovers. The ribbons only were damaged not the magnets and perf metal behind. They were from original the original owner and are said to have played perfectly before this happened. They are guaranteed to be in this condition so we will see when they arrive.

Then comes the tough part. Opening them to inspect and then closing them up until the last of the house is finished. Donna will probably request a time lock with total control over it be put on the shipping crates once they're in the shop. That or a warning shot from time to time out of the 375 magnum in her desk drawer

 

[User211]

Awesome Brad. Awesome.:bowdown:

I'm not so knowledgeable on Divas - but I know a man who is, LOL. If you really do get stuck I can probably get you an answer

Looking forward to the Apogee Diva Rebuild thread, as I suspect are others. Get those house jobs done quickly:ROFL:

Oh - bass ribbons have been installed on the Duettas.

 

[Brad225]

Good to hear the ribbons are in. Your one step closer to nirvana.

I don't see having mine finished for 1 1/2 - 2 years. That's the stuff dreams are made of.

I will probably have a multitude of questions to ask you and request as many pics of the internal metal frame structure as you have to figure out how yours were built. I have never seen what they actually look like up close only pics on the internet.

I am thinking about natural wood with clear finish. Is there any reason the front covering can't be done this way. I have only seen one picture of Apogees in a natural wood.

 

[User211]

Here's a Rich Murray natural effort. One of the stateside restorers. It may be that you have to get Rich or Bill on the ribbons if Graz won't let you have some to install directly. I hope he will, but I did warn you I've seen some early natural wood Scintillas, too.

Re frame bracing - I don't think what we've done for mine will be practical on a Diva. It will become an immovable object! Don't forget mine are thicker than the originals for a very good reason. The frame is built inside what would have been the original backplane, and then there's another backing attached to that. We're worried enough about the weight getting them down the stairs into my listening room. A Diva will weigh too much to be practical if this approach was taken. The stands bolt into the internal bracing forming a sandwich which still provides nice rear aesthetics, but I suggest you forgo that nicety.

What I think I would (first instinct - not too much thought) do is make an elaborate aluminium stand with cross bracing, which rises halfway or more up the back of the speaker. Something that can be bolted into the back of the speaker and be strong enough to keep any wooden frame true (prevent warping). It'll still look fine if done nicely.

Have a good look at them when they come through, Brad. Some good thinking will always provide a good enough solution! I'll have a chat with the restorer and see what he thinks.

 

[User211]

Rich had that pair on Audiogon for $27,000 IIRC. They went to someone eventually. With some good hand crafting by yourself, I'm sure you can manage massively less than that sort of money

 

[Brad225]

Thanks for the picture. Interesting you would have sent that one. I had pretty much (for now) decided on birds eye maple veneer over MDF for the front covers. I have some 30" wide pieces of the veneer in the shop left over from a previous clients job.

I am guessing you were referring to Bill Thalmann of Music Technologies? If I do try installing the bass panels myself I was planning on contacting him and plead my case. I do have some connection with him already as he preformed the Vacuum State upgrades to my Sony SCD-1 a few years ago.

It will all depend on the install costs. If I deliver them to him stripped and ready to install it may not be to painful to the pocket. I would like to try it just for the experience but from a resale point Bill doing it makes more sense.

Interesting you think they will become to heavy if I rebuild the interior structure similar to yours. How much do you think the back wave would be affected by bracing to the floor if it's not at the outside edges of the structure. I wasn't concerned with this on my CLSs because of the curved panel. I figured most of the sound wave would clear them.

I have the opposite install situation from yours. I will need to take them to the second floor of the house where my listening room is so weight will be an issue moving them.

As far as the retail of the pair Rich sold. I really hope or better not hit double digits in cost or the boss will be leaning hard on me.

Any time you have a thought of something relating my undertaking please post it here or PM me. I need all of the ideas I can get before starting.

Some time when you have a chance can you tell me what you did with the crossovers? I am planning on staying with the passive for now but figure they will need some new parts due to age.

Thanks

 

[User211]

Yes that's the Bill I meant. Stripped down delivery seems a good idea. Might reduce shipping charges a bit.

The Diva comes in at 68KG or 150 Lbs. That's pretty heavy. Adding a lot to that means those 2 flights of stairs might not be easy. Let's face it it'll be hard anyway. I live in a triple decker too, but the front door opens into the middle deck.

Rear wave bracing is no thicker than the magnets, and are aligned with the magnets so the speaker sees no change WRT the rear wave.

My Duetta cross-overs are external passive jobs with ESA Clarity caps and both foil and wire inductors - selectable for interest's sake. They connect by an umbilical - the whole you can see in the rear of the speaker a few pages back. The design is not the standard Duetta x-over.

For yours talk to Bill as much as possible. He's gotta be your best bet for Diva info, bet he has done a few.

The Divas Rich did above had new magnets - not sure what he put in but I doubt neodymium. Doing the work yourself must mean less than $10K I think.

The Diva is a more complex beast than the Duetta, and I have no experience of the 3 way x-over.

If Bill does the bass panels I believe you get KLM5 ribbons elsewhere. If you do them, you get KLM2. So the rule book says, anyway. KLM5 is appreciably more than a bit better than KLM2.

 

[User211]

BTW I'm sure Graz has some pure foil only mid-range ribbons for Divas. But the super-low impedance means things must be done elsewhere. Might be worth investigating.

 

[BrianBeck]

I think that this notion that "pure" aluminum ribbons must necessarily result in "purer" sound is a conflation of concepts. There are several potential advantages to using thin Kapton film backings:

1.) Constrained-layer damping of the aluminum foil to reduce resonances in several vibrational modes. Tap a pure foil strip and you'll hear the aluminum crinkling. Tap a Kapton-backed foil strip and you hear nothing.

2.) The Kapton substrate allows multiple conductors to be bonded as one unit so that the same musical current is used not once in the magnetic gap, but three times, in the case of the Diva. That's three times (or more) the resultant resistance (usefully) but also better use of the amp's current, essentially having a transformer inherently built into the ribbon rather than having to add a distortion-creating and BW-restricting transformer to drive the "pure" too-low resistance ribbon.

3.) Kapton reduces fatigue wear in the aluminum foil that will eventually lead to cracking and failure wherever the greatest bending stresses occur.

The only real downside of Kapton-backed ribbons that I know of is the slight additional mass. The significant effect of this is some degree of high-frequency BW reduction, but in the case of the Diva the midrange ribbon has to be rolled-off by a crossover anyway to allow the "pure" aluminum tweeter ribbon to sing by itself above 12 kHz. The midrange ribbon's mechanical response was factored into the electrical crossover already. If you changed the midrange ribbon's BW, never mind drastically reducing its sensitivity, you'd have to completely redesign the crossover.

 

[User211]

Great post, Brian. Are you still running your Divas?

I did think about the use of the word "pure", but just left it in. After all, its just aluminium, right?

I don't believe the foil can be tensioned as tightly either. I have heard stories of sharp breezes causes issues - particularly with the Scintilla foils. The foil only option is hardcore and potentially a pain in the butt, but I'm led to believe it really does work well sonically in practice.

I reason that the additional mass of the Kapton + glue + foil is offset against an ESL implementation by the much higher force the ribbon is subjected to. Check this post from someone who owns both types: http://www.apogeeacoustics.com/forum/viewtopic.php?f=4&t=570

Recent post from Graz about disintegrating foam (3E - 3 element for those who don't know). Trust me, if he says that, it works

"Suggested options;-

Strip and fit new 3E ribbons with supports, and ideally with the new circuit return system for best 3E results.

or

Strip and convert to a foil only MR system - involving crossover mods. This actually works rather well..."


To be honest I hate getting into amp debates : ) Somebody invariably gets offended..."

 

[BrianBeck]

... Are you still running your Divas?

Yes, I am, bi-amped with lots of tubes

I am still dealing with overly-reverberant room acoustics, but the sound is the best I've achieved in my 40 years of audiophilia. I also need to design my own version of a DAX to use tube buffers and get rid of all those opamps. Although I did mod the DAX with better devices and I beefed up the power supply, it's still a weak link.

 

[Bernard]

Yes, I am, bi-amped with lots of tubes

I am still dealing with overly-reverberant room acoustics, but the sound is the best I've achieved in my 40 years of audiophilia. I also need to design my own version of a DAX to use tube buffers and get rid of all those opamps. Although I did mod the DAX with better devices and I beefed up the power supply, it's still a weak link.

Burson Audio makes opamps out of discrete components. Have you considered them?

 

[BrianBeck]

Burson Audio makes opamps out of discrete components. Have you considered them?

You probably forgot that you had asked me that same question about a year and half ago:

http://www.martinloganowners.com/fo...gee-Comparison&p=152047&viewfull=1#post152047

I guess some suggestions are worth repeating if they don't sink in the first time

My views really haven't changed. In fact I've contemplated adding a tubed line stage function into the new "DAX" box with a bit of gain, input selection relays, and remote volume control. However, I've made no progress toward a tubed unit yet. Too many projects...

But thanks for the suggestion!

 

[Bernard]

You probably forgot that you had asked me that same question about a year and half ago:

http://www.martinloganowners.com/fo...gee-Comparison&p=152047&viewfull=1#post152047

I guess some suggestions are worth repeating if they don't sink in the first time

My views really haven't changed. In fact I've contemplated adding a tubed line stage function into the new "DAX" box with a bit of gain, input selection relays, and remote volume control. However, I've made no progress toward a tubed unit yet. Too many projects...

But thanks for the suggestion!

Yes, I had forgotten; my apologies.

 

[BrianBeck]

Yes, I had forgotten; my apologies.

No apologies needed! This is all in good fun!

 

[User211]

Signs of life, but not here at home yet. This is, as far as I am aware, the best pair of Duettas in the UK bar none. I hope:ROFL:

 

[User211]

Rear of speakers showing external x-over with components that wouldn't fit internally, umbilical, massively rigid stands, much thicker back "plate" and a hint of the aluminium frame bracing going on inside. The stands are clamped directly into the internal aluminium frame. This sucker is rigid.

Not pretty from the back I suppose but it is a case of form over function. We could "black sock" them but I kind of like them like that. Looks mean. Better photos when I get them of course.