Visit to Henk van der Hoeven -- Apogee Acoustics Re-builder/Restorer

[microstrip]

I don't know the model, but it was 130 W/channel, 240 into 4 ohm, so 480 bridged that I heard. Henk normally uses it for his bass panels on the grands but played it on duettas for demo

Thanks, I now traced the old connection between the SA250 mkIV and the Duetta Signatures. Terrible, also I know there is a pair of strongly Dark Grey Signatures laying around in a garage in my neighborhood and I still have a tube with ribbon tweeters spares in my closet ... But each is twice as heavy as my Plinius!

 

[ddk]

Thank you, David.

If two pairs of Manley Ref 350s are only passable, that says something.

Do you think the problem was lack of current? Do you think the MB-750s in tetrode mode (about 700 watts) would have been more than "passable"?

It was lack of current & power! Published power ratings aren't all measured the same, you can't go just go by that, regarding the tetrode mode the Ichibans could do it but you'd never think about if you had heard it ! It's all distortion.

david

 

[FrantzM]

Hi

I am with ddk once more on this. I wasn't a huge Apogee fan but came to respect what they did much later and I did , briefly , own a pair. They crave power. All of them. You will find some people running them with tubes and I remember there was a fellow in Brooklyn, NY who was running the Scintilla with some Tubes. I didn't think much about the sound then and would still not today. He was however pleased and kept it for the longest time, most people who heard his set-up didn't share his opinion but that sound did float his boat... OTOH One of the best Apogee set-up I heard was a Tri-amped Diva with Krell KMA something can't remember but must have been 600 watts in each panel at least! Those were the days of Krell running Class A or very close to it in most of their range .. It did sound tremendously good IMO then. Knowing what we know about room interactions it might have sounded better with better treatments but ...
The point is that with low sensitivity you need power and from what I remember Apogee were anything but high sensitivity. Googling the archives of Stereophile reveals a sensitivity of 80 (!!!!!!) dB/W/m for the Duettas... The Diva had a nominal impedance of around 3 ohms, if you were to believe the manufacturer , much closer to 2 ohms in most of its FR , dipping from time to time around 1.5 ohms and it was likely a 82 dB/W/m speaker perhaps less... The new Apogee rebuild or inspired speakers are perhaps sensitive but the original weren't and tubes friendly they weren't either.

 

[thekong]

Here is how the custom foil only ribbon in my Duetta moves during play at loud level!

Active Xover by Pass XVR-1, only a custom transformer from Graz to raise the impedance of the ribbon.

 

[bonzo75]

OK guys...back in the loop...[mixing 2 rooms but] got it now. I'll just watch and listen for now...

When you come back after a satisfactory session we will still be theoretically discussing if tubes can drive your speakers

 

[bonzo75]

Hi

I am with ddk once more on this. I wasn't a huge Apogee fan but came to respect what they did much later and I did , briefly , own a pair. They crave power. All of them. You will find some people running them with tubes and I remember there was a fellow in Brooklyn, NY who was running the Scintilla with some Tubes. I didn't think much about the sound then and would still not today. He was however pleased and kept it for the longest time, most people who heard his set-up didn't share his opinion but that sound did float his boat... OTOH One of the best Apogee set-up I heard was a Tri-amped Diva with Krell KMA something can't remember but must have been 600 watts in each panel at least! Those were the days of Krell running Class A or very close to it in most of their range .. It did sound tremendously good IMO then. Knowing what we know about room interactions it might have sounded better with better treatments but ...
The point is that with low sensitivity you need power and from what I remember Apogee were anything but high sensitivity. Googling the archives of Stereophile reveals a sensitivity of 80 (!!!!!!) dB/W/m for the Duettas... The Diva had a nominal impedance of around 3 ohms, if you were to believe the manufacturer , much closer to 2 ohms in most of its FR , dipping from time to time around 1.5 ohms and it was likely a 82 dB/W/m speaker perhaps less... The new Apogee rebuild or inspired speakers are perhaps sensitive but the original weren't and tubes friendly they weren't either.

On Sensitivity, this is from Enjoy the music review of Analysis Ammphitryon, where he says for a ribbon line source, at 4m it will sound twice as loud as a cone speaker with the same sensitivity
==================

The rated sensitivity of all Analysis speakers is 86dB/W/m — on the face of it, hardly a high-efficiency number. That being so, how can they play so loudly with medium-powered tube amplifiers? Because attenuation of the sound wave traveling through the air is reduced due to the much larger dimensions of the planar membranes and ribbons. Theory stipulates that with the exception of a small area close to the sound source ("nearfield"), the sound wave experiences an amplitude drop of 6dB for each doubling of distance to the listener. Within the nearfield the attenuation is only 3dB. The nearfield extends to roughly three times the dimension of the driver. Although this is negligible for an ordinary tweeter (a few centimeters), the nearfield for a 2-meter-tall ribbon tweeter reaches about 6 meters. The following table compares loudness for two different drivers of the same rated sensitivity, according to the distance from a listener:

Distance: 1m 2m 4m
Ordinary tweeter: 86dB 80dB 74dB
2 meter ribbon: 86dB 83dB 80dB

This means that at a one-meter distance both drivers' outputs are about the same, but at four meters the planar loudspeaker sounds twice as loud.

 

[bonzo75]

If Justin is being limited with his SPL, it is the amp that's the problem not the ribbon. His amp needs to provide more current (probably limited by power supply) to raise another 6db. If you want to challenge that contact A.Wayne offline, he will explain.

As for me, I am shortlisting, at various price ponts, used Aesthetix Atlas, Symphonic Line class A, bridged Luxman M800 amps, all to compare with Ayon Orthos XS. Of course I could demo more amps as well. All in the next few years.

If I was in the US I would just get a TRL and compare it to a high powered quality SS amp and be done

 

[spiritofmusic]

Any opinions as to whether Apogees can work with the mids and treble ribbons positioned outermost, bass ribbons innermost?
Or are they consistent in needing the mids/treble ribbons innermost?

 

[bonzo75]

You will have greater sound stage, maybe less imaging with ribbons on the outside

 

[spiritofmusic]

Henk has conveyed to me 2m between Divas would be OK
This enables a few centimetres clearance between top outer corner of Diva and descending eave, and a metre clearance half way down the Diva and the eave/side wall
If I position the Divas with mids and treble ribbons outermost, that will give me centre-centre distances of 7.5' for bass ribbons and 10' for mids and treble ribbons

 

[Ron Resnick]

The speakers I think I would be most interested in are the Full Ranges. Rich at True Sound Works does not offer a passive crossover option for his re-built Full Ranges. (He recommends the Pass or First Watt crossovers.

What are the current options, if any -- and please do not include me building passive crossovers myself as an option -- for using passive crossovers on Full Ranges?

Does Henk or Jon re-build original Apogee passive crossovers? Are there current manufacture passive crossover options people use?

Or is a passive crossover with a Full Range just a bad idea?

 

[Zero000]

If Justin is being limited with his SPL, it is the amp that's the problem not the ribbon. His amp needs to provide more current (probably limited by power supply) to raise another 6db. If you want to challenge that contact A.Wayne offline, he will explain.

A per my previous post, Kedar, the constraint on max SPL with the Accuphase amps is not power, but the excursion limitation of the bass panel. It doesn't matter how much current you have beyond a certain point, as the bass panel with either cop out and distort due to high very low frequency content in the mausic being played, or with little LF content, just reach its max SPL capabiltiy i.e. max excursion ability.

The Jim Keltner you were listening to you played at about the max level achievable for a Duetta.

 

[Zero000]

Henk has conveyed to me 2m between Divas would be OK
This enables a few centimetres clearance between top outer corner of Diva and descending eave, and a metre clearance half way down the Diva and the eave/side wall
If I position the Divas with mids and treble ribbons outermost, that will give me centre-centre distances of 7.5' for bass ribbons and 10' for mids and treble ribbons

I had my Duettas the wrong way round for quite a while. I liked it, but I had to angle them in a lot to make it work WRT soundstage. Expect around 30 degrees from "flat straight at you".

 

[spiritofmusic]

So Justin, the "correct" way is mids/treble ribbons innermost?
Best balance for imaging etc as Ked suggested?
In my room that will mean the mids/treble ribbons on the Divas would be approx 7.5' centre-centre (bass ribbons 9.5' to 10' centre-centre)
Do you think this is a compromise on a speaker which is 6' tall and could easily be listened to at 12'-15' distance?

 

[spiritofmusic]

I know this is an impossible question to answer
But anyone out there familiar with Apogees' interaction with side walls and ceilings may be able to surmise
As my room ceiling slopes down from a mid point maximum apex of 10', to 4' high side walls at overall room width of 18', the clearance of each Diva on outside will vary from tightest spot of 6" at very top outside corner to eaves, to 24" a third of the way down, to 36" at base between outside bottom corner and side wall

I'm always hearing that unlike box speakers, but like horns, Apogees interact minimally with ceilings, side walls and floors
Just what could I predict with in effect very close proximity with side boundary at top of speaker widening out to normal proximity as the height descends

 

[spiritofmusic]

Gentlemen
I realise my qs are bordering on the insane end of ocd LOL
I'll bow out for a while and let others in
But any insight to my dilemmas I'd be most grateful for

 

[RBFC]

I had my FRs in a 27x15 room with 8ft ceilings. I had little issue with side walls or ceiling reflections. I used stacked ASC tube traps in the corners behind the speakers and stacks where the back wave would have first reflection to the listener's line of sight. I had many audiophiles drool over the presentation, so it must have been reasonably set up. Still miss those speakers....

Lee

 

[KeithR]

When I compared the tetrode mode to the triode mode on the VTL MB-750s I preferred the triode mode on vocals and acoustic instruments. I kept the amps in triode mode and I have never switched them back to tetrode. (I understand that many people who prioritize rock and symphony orchestra prefer the tetrode mode.)

For people who like tubes in general the SET "effect" on the midrange provides even more "sweetness" and "liquidness." Since I enjoy the sound from powering an electrostatic or ribbon driver with 300 watts of VTL in triode mode I can't help but wonder if I can power the same drivers with 170 watts of N.A.T. Magma SET.

This, I believe, is the same thought process driving SpiritofMusic's questions.

Tubes are common with stats, for sure. Just need good 4 ohm taps (or even 2 ohms like some Mac amps)

High powered SET is likely to lead to high powered distortion as SETs typically have increasing distortion with power. To me, SET isn't as much about sweetness or liquidity, but rather the first watt simplicity and open/vividness/holography the amplifier provides. It therefore is ideal at a couple of watts, period. Rather than an effect, its a design philosophy. And those designs typically require higher efficiency speakers than Apogees. SETs also are not happy with low impedance and impedance changes. When impedance nosedives, SETs produce much less power unlike other topologies - so its a double whammy. A question for NAT is how much distortion at 100 watts? If anything like the Wavac, its a lot. 150 watt SET in that case is over 10% distortion.

Tetrode tubes and SS would be much better wagers for these speakers and negative feedback controls might prove useful like on the latest Siegfrieds. But the Apogee guy himself designed with Krell, so re-inventing the wheel may not be necessary.

Bonzo - i hear the same "bass drum out of a woofer, violin out of a midrange" on many speakers these days unfortunately. The big Wilsons lately have been like that for me, although some is probably setup related.

 

[bonzo75]

The Krell was mainly for the Scintillas which went down to 1 ohm and also had a different house sound

 

[bonzo75]

Here is how the custom foil only ribbon in my Duetta moves during play at loud level!

Active Xover by Pass XVR-1, only a custom transformer from Graz to raise the impedance of the ribbon.

Kong,
1. What is the impedance of your ribbon now?
2. Who restored this speaker?
3. You have the pass because you are using two amps? How are you exactly doing this?