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

[Ron Resnick]

Thanks KeithR.

Was thinking the same here .. very different from what one would expect from a no feedback design ...Would like to know too.

Would someone please get to the bottom of this so SpiritofMusic can have some peace?

 

[bonzo75]

Hi Joel, who is a 6 moons reviewer, told me the same thing with Maggies - he thinks too high damping factor keeps the panel too tight while a lower one let's it be freer and gives better bass

 

[microstrip]

That amp has ultra linear and tetrode modes. Which measurement is it? Isn't a typical no negative feedback curve.

Paul Miller measured the NAT Transmitter tube power amp in the ultra linear mode. BTW, the output impedance at 4 ohm is around .85 ohm.

 

[Zero000]

One more point on the Duetta, in the video I posted, you could see the front cover of the speaker was off, as I was in the process in repainting the cover. But to my surprise, the sound was much more transparent with the cover off, so it never went back up. My friends made jokes about it being like the Predator taken his mask off

If you can't stand that look (to be honest, who in his right mind could? ) , the next best thing is probably taking the protective grill off, but you have to be very careful not letting anything gets into it!

Interesting. The grille material Jon Oakey uses - I just cannot hear any difference with the covers on or off. Absolutely none. And this is from a person who always removed grilles from speakers he has used in the past.

TBH I think Jon said it is the same as Apogee used. Can you say the same of your grilles? If so, I am amazed you can hear a difference.

 

[bonzo75]

Ked, what is Florian's setup? What NATs does he use with his Grands?
And Gallant Diva? Uses two pairs of 120W Transmitters with his Graz Divas I believe?
Is there any suspicion their rigs are underpowered or deficient in any way?
What I mean by this is maybe the NATs with Apogees in these systems sound good in one respect, but inappropriate otherwise. Michael is alluding to having bass or treble, but not both, with SETs, esp thru the Apogees
Or are Apogee/NATs combinations with these guys in very tight spaces where the lack of megaWatts is less of an issue?

Florian uses transmitters. Gallant diva uses TRL. There is one guy using NAT transmitters with FR but I have no contact with him. There is apparently a guy in the US who owns each model of the originals including the grands all with boulder amps. Unfortunately these guys are not on any forums.

My shortlist is symphonic line Kraft (cheapest at used price 6 to 7k), MSB 202 will have more resale value, bridged Luxman are excellent though more expensive and start getting into viola bravo price category, and on valves ayon orthos. Apart from Luxman I haven't heard any.

If anyone has negative comments on any of these amps apart from the fact that they are SS, please feel free to PM feedback in case you don't like posting negative comments

 

[bonzo75]

You are an experienced audiophile and a wise man. Unfortunately we were being guilty of one usual "technofile" sin - we were extrapolating data published 12 years ago by Stereophile on another amplifier and exposing our "official SET culture", with complete lack of knowledge of facts or reality.

Your PM about these amplifiers triggered my attention and I have now read the Hifi News Paul Miller measurements on the Nat Transmitter. Great news : it passed gloriously the dynamic power tests versus distortion using the SET standards up to 80 Watt, only failing at 1ohm! The shape of the distortion versus power curve is the opposite we were describing. BTW, the German Audio review is really enthusiastic - 140 points!

So IMHO the technical verdict must be - worth being considered for listening when used with some of the speakers being referred.

Thanks for pointing us such interesting amplifiers.

Thanks. Their pre is the best I have heard. The entry level too beats much more expensive ARC stuff. Just one thing though...they are very dynamic, great on separation, bass, and make instruments sound note clear and rounded with better tone. They are not forward and airy as audio research or Jadis though. So the difference normally shows on orchestral. I want to compare it to the ypsilon pre some time. And I want to check how either one drives an SS Amp. For some reason CAT was voiced along with symphonic line and symphonic line is the one SS amp that the CAT designer Ken recommends to his clients who have to use an SS amp. Caesar has that combo

 

[Zero000]

Hi Joel, who is a 6 moons reviewer, told me the same thing with Maggies - he thinks too high damping factor keeps the panel too tight while a lower one let's it be freer and gives better bass

TBH the Parasound A21 had a really high damping factor. That had a slightly choked feeling in the lower bass control which you lose totally with the 211 amps. The 211s, within their power constraints, give the quickest, fastest and best bass of any amp I've heard. I kid you not. Annoyingly, I don't know the 211 amp's measured DF, but it is likely much, much lower than the Parasound's in numerical terms i.e. the A21 is some 10,000 odd. When you get over 100 it isn't supposed to make any difference. Suspect the 211s well below 100.

 

[Zero000]

Just been texting Ked, and we've worked out he prefers the 211 mid range to the Accuphase M-60s. Not hard to understand that. Seems like he found the 211 mids more involving. I think the 211 mids are very entertaining myself.

 

[bonzo75]

Paul Miller seems to have reviewed the older 80w SET. Since then there have been many upgrades, the transmitter is 120w, the magma new is 170w, and you can get an SE (special edition) version for each with premium parts

 

[spiritofmusic]

Justin, OCD is an issue even when my rig is packed away awaiting installation in the new room by Oct/Nov LOL
KeithR's point about the beauty of SETs being the first few Watts really chimes with me, but NAT may be one of the few (Kronzilla maybe too) SETs that can maintain that beauty well towards the end of it's power/output range
It looks telling that the Paul Miller report on the Transmitters gave it an amazing technical thumbs up in saying distortion not an issue until 80W or so (don't even go there with the Wavacs)
There must be something in Florian running two pairs of Transmitters on the Grands (although that's only part of the story, the Grands are semi-active, yes?)
So, this is quite the quandry.
On paper, SETs having a cat in hell's chance of working well with SETs, but NATs having amazingly resillient test findings, and at least one user enthusiastically extolling their virtues on Apogees.

Btw, that review of Ken Kessler's re the Transmitters was quite the read - he REALLY loved them, coming from someone who normally finds so many things wrong with SETs otherwise. Certainly NAT build quality is heroic, and use of dual tank-like transformers adds to their almost SS-like grip with plenty of tube juiciness.
i SOOO would like there to be a reliable synergy between NAT and Apogees, esp the Divas, in my size room.
The shopping list for Graz Duettas or Divas and Transmitter trade in price is basically my budget for the new Zu flagship released next year.

 

[Zero000]

Marc - have you got any idea of the level of decibels you'd like your system to be able to achieve at 12-15ft?

 

[spiritofmusic]

Well, I was at Audiophile Bill's investigating the GG, and loud passages were measuring 75 odd dB (is that right Ked?)
I can't imagine playing much louder than that consistently

I'm sure NATs could get Divas or Duettas to go loud
My concern is that the force may be there, but not the beauty

This reminds me of a question I always forget to ask - do the Apogees, even with mega Watts on tap, HAVE to be played loud to gel/come alive?
Or are they good at more intimate levels eg late night listening with a glass of beer in your hand?

Horns and my Zus are really tangible with the wick down, and I personally hate speakers that have to be played loud to sound any good

 

[bonzo75]

No it was a bit higher. I need 90 at least on peaks, normally 85. Depends how long i am listening.

Grands and FR have to be biamped, hence he is using two pairs

 

[spiritofmusic]

So Ked, were we playing loudly enough at Bill's?
That was quite ok for me
I'd only really play more loudly when no one else at home (our place is very detached)
Your thoughts on Apogees at moderate or even low levels
Intimate listening when you're not trying to air conduct?
So many speakers are poor lower down, and often these are insensitive models. As are Apogees..

 

[bonzo75]

At Henk's they sounded great on moderate volumes. Justin usually plays very loud. He thinks he is 20 and in a night club

 

[spiritofmusic]

So Ked, we've read plenty of discussion on Duettas, FRs, Grands
But not so much on Divas
How do you think they compare?
My room, even though plan area can stretch to the biggest Apogees, ceiling concerns mean I'm "limited" to Duettas and Divas
Henk's advice that Jon agrees with, is to go Divas
In some way they are in the SweetSpot of the range
Steady 4 Ohms like the Duettas and similar if not marginally better sensitivity
But separate tweeter and mids ribbons unlike the Duettas
And bass ribbon likely to energise my space better than the Duettas
Greater height, more scale
What's not to like?
The Dutch web review HiFiAdvice says the Duetta is the more "fun" speaker, with bloomier bass, but the Diva has greater scale, more accurate bass, but a darker, less sparkling treble
The author was confused by this because the Diva has a dedicated treble ribbon, and admitted the Diva treble was more "natural", just less marked than the Duetta
He labelled the Diva "dark" in tonal balance
Crossover changes made a difference but not enough to totally change this outcome
***PS I am paraphrasing several pages of two reviews, subtleties may be missing in my words***

 

[bonzo75]

Restored apogees can sound different, so can't say. I don't waver to extrapolate my experiences to Divas I have not heard. They need a bigger room than a duetta, yours is fine, they will play louder, are three way.

I will go duetta and then upgrade to FR when I get a bigger room. FR is THE final speaker for me.

I have a heard an old diva without all the upgrades and musical fidelity high powered amps that sounded boring on low quality digital but sounded excellent with the acoustic solid TT, Kuzma 4p and a90 - some low cost phono

 

[henk]

So Ked, we've read plenty of discussion on Duettas, FRs, Grands
But not so much on Divas
How do you think they compare?
My room, even though plan area can stretch to the biggest Apogees, ceiling concerns mean I'm "limited" to Duettas and Divas
Henk's advice that Jon agrees with, is to go Divas
In some way they are in the SweetSpot of the range
Steady 4 Ohms like the Duettas and similar if not marginally better sensitivity
But separate tweeter and mids ribbons unlike the Duettas
And bass ribbon likely to energise my space better than the Duettas
Greater height, more scale
What's not to like?
The Dutch web review HiFiAdvice says the Duetta is the more "fun" speaker, with bloomier bass, but the Diva has greater scale, more accurate bass, but a darker, less sparkling treble
The author was confused by this because the Diva has a dedicated treble ribbon, and admitted the Diva treble was more "natural", just less marked than the Duetta
He labelled the Diva "dark" in tonal balance
Crossover changes made a difference but not enough to totally change this outcome
***PS I am paraphrasing several pages of two reviews, subtleties may be missing in my words***

I think you need to be a little patient regarding the diva review you've read. I've just finished measuring 4 original diva filters, and I've found that the filter schematics I've been using up till now to upgrade the filter is quite different from what I'm measuring in some key area's.

For one: the bass coil that I measure has only about half the inductance of the filter schematics I downloaded from Jon's site.

Also, the tweeter filter needs to be modified to accomodate the lighter, higher impedance tweeter that Graz likes to deliver. This newer tweeter is lighter, and this faster.

I would not be surprised to find that the HifiAdvice diva's use the lighter tweeter with the original tweeter cpacitor, resistor and coil values, hence yielding a darker sounding tweeter....

 

[spiritofmusic]

Henk, as I said, my words could easily paraphrase things too simplistically
If you make a pair of Divas up for a customer currently, are you minded to make changes that might compensate for this darker top end in the HiFiAdvice review pair?
In other words, would a pair of Divas today from you likely have a more sparkling top end?
For me I'm not averse to tonally darker sounds, but it seems like the review Divas were maybe too dark?

 

[henk]

Marc,

The only reason those diva's may contain these anomalies is because I wasn't aware of the issues at the time.

I don't even know if these diva's contain original spec Graz tweeters or SLW tweeters...

I'd have to measure them to be shure.

So the answer is a resounding yes. I will never restore a pair of diva's again without compensating the filter for the exact type of tweeter used