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

[spiritofmusic]

Keith, I'm minded to agree with you
My idea would be to upgrade my 60W/ch NAT SE2SEs SETriodes to 120W/ch Transmitter or 190W/ch Magma SETetrodes

But there is a lot of wisdom in your words I believe

The q is whether a "benign" load of 4 Ohms across all three ribbons in the Duettas and Divas, and 2-3 dB improved efficiency from the Graz ribbons, takes them from the need for Krell to a more compliant requirement

 

[spiritofmusic]

Lee
My issue is that to enable 2m width between speakers, the top outermost corners of the Divas would be mere inches from descending eaves

That on paper seems like asking for trouble

But good to hear your FRs were relatively side wall and ceiling agnostic

So just why did you move away?

 

[Zero000]

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?

I told you there were pure foil Duettas... Disadvantage is the transformer, advantage is very low mass ribbon, disadvantage is the fragility, disadvantage is cost.

I still think, though I have not witnessed it, that it must provide the best SQ.

Suspect transformer quality is important.

 

[Zero000]

The q is whether a "benign" load of 4 Ohms across all three ribbons in the Duettas and Divas, and 2-3 dB improved efficiency from the Graz ribbons, takes them from the need for Krell to a more compliant requirement

I'd like to see some proof there is a 2-3DB gain in efficiency in Graz ribbons. I cannot think why this would be the case. The only thing that can make a difference is more powerful magnets or reduced magnet/ribbon gaps, at the price of excursion and hence reduced volume capability.

 

[bonzo75]

KONG - WOW WHERE THE F ARE YOU LOCATED? I just went through some of your past posts. You have FR and Duetta both?

Ron, he also has the Aesthetix IO. VDH Colibri.

 

[RBFC]

Lee
My issue is that to enable 2m width between speakers, the top outermost corners of the Divas would be mere inches from descending eaves

That on paper seems like asking for trouble

But good to hear your FRs were relatively side wall and ceiling agnostic

So just why did you move away?

Divorce has a way of altering one's audio system.

Of course I can't say how the eaves/slant will affect Divas in your room. All I can say is that Apogees are the most forgiving large speakers I have heard when it comes to side wall issues.

Lee

 

[Ron Resnick]

KONG - WOW WHERE THE F ARE YOU LOCATED? I just went through some of your past posts. You have FR and Duetta both?

Ron, he also has the Aesthetix IO. VDH Colibri.

Let's go!

 

[thekong]

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?

My Duetta was restored by Graz nearly 10 years ago, and that was the first pair fitted with the foil only ribbon. According to Graz, the ribbon (together with the transformer) has an impedance of around 2.3ohm. The transformer was a custom design by Graz, similar to the ones used in his Definitive.

With the foil only ribbon, the original passive Xover could not be used, so the speaker was active bi-amp with a pair of Sonic Frontiers Power 3 (220W, 8 ohm) for the bass, and a Sonic Frontiers Power 2 (110W, 8 ohm) for the mid/treble ribbon.

My Fullrange was restored by Rich in the US. It is being active bi-amp driven with the above Sonic Frontiers combo, or 2 pairs of CJ Premier 8.

However, I am in the process of moving to a larger place, with an audio room of around 17’W, 28’L, 12.5’H, and I plan to active tri-amp the Fullrange with a pair of Pass X600.5 and 2 Pass X350.5. The foil only midrange ribbon, with 0.25ohm, would need a transformer to raise the impedance.

I am in Hong Kong, so quite far away from you guys

 

[Lissnr]

Hello Kong: You run Duettas with SF Power 3 / Power 2 biamp...!!
FR's with CJ Premier 8's !!!
And are about to move into a perfect sized room for the FR's powering them with Rich's favorite perfect amps: the X600.5 monos and a pair of X300.5 TRI-amped!!!!!!!
Let me say just one thing and I'll shut up: Oh M G!!!! You are my hero!!! wow Wow WOw WOW WOWWWW!!!!!!!

 

[thekong]

Hi Lissnr, thank you for the compliment! When my move is done, you are welcome to visit my place should you be in Hong Kong.

Regarding placement of panel speakers, first I must say I am a soundstage freak, and the best way I have found is the ”Room Coupling” method by a Magneplaner guru in Hong Kong :

http://www.1pekingroad.com/zaspx/replies.aspx?topicsno=3&subjectno=874&uppersubjectno=874

Some interesting points about this method:

1. If you have a rectangular room, and you place the speakers against the shorter wall, then the speaker would usually end up at around 40% of the room’s length from the front wall (i.e. if your room is 20’ in length, the speaker will usually be around 8’ from the front wall. I have a more or less 15’W, 33’L, 13’H room, but it is truncated at the back so it is more like an L shape rather than rectangle, and both the Fullrange and Duetta ended up around 11’ from the front wall.

2. The speaker will be very close to the side walls. Both my Fullrange and Duetta are placed within 12” from the side walls.

3. As the name “Room Coupling” implies, the room seems to work with the speaker to improve its efficiency. For example, in the room mentioned about, with the Duetta driven by the Sonic Frontiers amps, my friend clocked a peak SPL of 105db at the listen position, and the speaker wasn’t showing any stress. But then, he was just using an iPhone, so I am not sure how accurate the measurement was.

Since positioning your speaker is free, I encourage everyone to try it out to see whether it works for you!

 

[RBFC]

I agree. I had my FRs about 13" from side walls and 7ft from the wall behind them.

Lee

 

[thekong]

This is a photo taken by Thomas Schick of Schick tonearm when he visited a few years ago

 

[bonzo75]

Amazing stuff. You are the King, Kong.

I must say a couple of things though - I understand that placing close to side walls can reiforce the bass even more. I prefer panels such the triangle is right, if they are too wide w.r.t the triangle it feels like there is a hole in the middle of the stage.

 

[bonzo75]

VDH Colibri can be so explosive. That into FR is going to be mindblowing.

 

[Graz - APOGEE ACOUSTICS]

Michael - you didn't mention your room is half the size of HK!!

A quick note re comparisons between Installers - ALL EXCLUSIVELY use the KLM/KLM5 ribbons in their rebuilds, the motors if you like. Accuracy, including magnetic reworks using alignment protractors from me improve efficiency only marginally by eliminating errors in original mfr magnet alignment. The ribbons we make here use blueprinted and certificated tight tolerance original materials, machined on our proprietery cnc ribbon machines in a high tech dedicated facility. Where the Installers differ - is their frame/chassis work. All have been taught my version of classic tuning, and to the best of my knowledge use it. I work closely with all of the Installers to achieve the best outcomes on restored speakers possible.

Take care - Graz

 

[LL21]

Hi Lissnr, thank you for the compliment! When my move is done, you are welcome to visit my place should you be in Hong Kong.

Regarding placement of panel speakers, first I must say I am a soundstage freak, and the best way I have found is the ”Room Coupling” method by a Magneplaner guru in Hong Kong...

View attachment 28170

This is a photo taken by Thomas Schick of Schick tonearm when he visited a few years ago

Isnt our fearless leader and founder of WBF in Hong Kong now? I think there is a whole thread dedicated to all the restaurants and shops he is going to be seeing! Steve - if you are watching this, please chime in even if you cannot make [yet another] stop on your action-packed vacation.

 

[spiritofmusic]

Michael, I'm getting quite the rush looking at your system and only imagining how it might sound, especially in your proposed space
This is surely one of the premier setups anywhere in Creation

Hard to compare your Graz ribbons to others because of the über low impedance foil ribbons/need for transformers

For us mere mortals, using "normal" impedance non foil ribbons, eg uniform 4 Ohm Divas or Duettas, in a room same width as yours, somewhat deeper, but not as high, could you see powerful SETs being capable/practical/suitable?
120W ok? 190W?
Or is this desire mere illusion?
Do I need megaWatts tubes or SS, and nothing less?

 

[Zero000]

Michael - you didn't mention your room is half the size of HK!!

A quick note re comparisons between Installers - ALL EXCLUSIVELY use the KLM/KLM5 ribbons in their rebuilds, the motors if you like. Accuracy, including magnetic reworks using alignment protractors from me improve efficiency only marginally by eliminating errors in original mfr magnet alignment. The ribbons we make here use blueprinted and certificated tight tolerance original materials, machined on our proprietery cnc ribbon machines in a high tech dedicated facility. Where the Installers differ - is their frame/chassis work. All have been taught my version of classic tuning, and to the best of my knowledge use it. I work closely with all of the Installers to achieve the best outcomes on restored speakers possible.

Take care - Graz

One of the things I constantly expressed to Jon was the need for accuracy and alignment when building Interstella. He definitely achieved that. And it makes a very real difference I believe when it comes to the performance of the speaker.

I also think your clamping mechanism for the Duetta MRT does good things, Graz. It seems to almost entirely erradicate ribbon tiwst and provides more stable imaging as a result.

That the current restorers are capable of building speakers way beyond the level of QA Apogee orignally applied is beyond question, IMHO.

However, to achieve much better quality than original Apogee, any prospective purchaser must expect to pay for these standards of workmanship. And the more funds you can provide, the better the result will be. As with most things in life.

 

[bonzo75]

However I had no idea Duetta came with Pure Ribbon Foil as well, or is this a one-off Graz? Does this improve midrange, but I assume lower impedance will restrict the amps that can be used? Interestingly while the FR has wonderful mids with its pue foil the Grands also have a great midrange despit being Kapton backed.

 

[bonzo75]

Looking up tix. Not that bad. Actually cheaper than west coast. East Coastish prices. Lose a day while going, gain one on the way back. Hmm. Brit passports need visa?