Apogee Full range

[Brian Beck]

That’s a new one on me. Did they ever actually build any of these to sell? Since one cannot squeeze anywhere close to 1000 W out of a pair of 300Bs, they must be using the 300B as a voltage amplifier and following that with a FET follower stage, and then a low-ratio OPT. It’s a hybrid then. The 300B does make a fine voltage amplifier with extraordinarily low distortion. It makes a fine line stage for example.

 

[christoph]

Pretty confident, but I have to prove that to myself. The future configuration that I posed would be 1-ohm amplifier taps directly driving 1.8 ohm woofers. So the amp will be very happy, but max power may be reduced a bit. I will also try the 4-ohm taps directly driving the 1.8 ohms. That reverses the mismatch, but maybe it would work. The amp does not have 2-ohm taps, which would have been ideal.

Another option is to put the two D-250 channels in parallel. The 4-ohm taps then become 2-ohm taps and the power goes up to 500 W in one combined channel. That would probably work exceedingly well driving the woofers. I would then need more amps for the mids and tweeters, but I know where I can find two more D-250s. Like I need even more glowing 6550s in my room! I do have to say that one 250 W channel of the D-250 driving a woofer through the interface transformer seems to have enough power. I was able to just reach clipping on loud bass drum whacks, but that level was very, very loud.

Who knows what will work best? Audio can be full of humbling surprises. I will keep you posted if anyone is interested in my progress with these speakers and these amps.

Congrats on the wonderful FRs, even driven by tubes
Please keep us in the loop.
If I ever buy an additional Apogee, it will definitely be the FR
BTW. I had excellent results on my Scinnies with Lamm hybrids. The drove the Scinnies with absolute ease and sounded heavenly doing so

 

[Brian Beck]

Thanks. I’ve heard a lot of good things about Lamm amps. I need to listen to a pair some day.

 

[LL21]

That’s a new one on me. Did they ever actually build any of these to sell? Since one cannot squeeze anywhere close to 1000 W out of a pair of 300Bs, they must be using the 300B as a voltage amplifier and following that with a FET follower stage, and then a low-ratio OPT. It’s a hybrid then. The 300B does make a fine voltage amplifier with extraordinarily low distortion. It makes a fine line stage for example.

Thanks...do you like the premise of this design? If so, what might be its potential characteristics/strengths? Does it end presenting any of the character of a traditional 300b amp?

 

[Brian Beck]

Thanks...do you like the premise of this design? If so, what might be its potential characteristics/strengths? Does it end presenting any of the character of a traditional 300b amp?

It’s really hard to judge very much at all from the scant description. And impossible to judge its potential sound quality, of course. My guess is that the 300B is for the first stage of voltage gain only. Since the mu of a 300B is only 3.8, they probably could squeeze no more than 11 dB of voltage gain out of it. A typical power amp would need to have about 26 dB of voltage gain. That means that they need an additional 15 dB of gain, or even more if feedback is employed. So there must be a SS voltage gain stage in there (or an interstage transformer) followed by SS followers in the output stage to drive current into the speaker. I am assuming there are no other tubes besides the sole 300B, but I really can’t tell. So, if I am correct in my guesses, the 300B is being touted mostly for its marketing value, although it is a valid voltage amplifier. This is not to say that a competently-designed hybrid can’t sound great, only that we cannot deduce that the traditional 300B amp (SET or PP) sound character will remain here.

 

[LL21]

It’s really hard to judge very much at all from the scant description. And impossible to judge its potential sound quality, of course. My guess is that the 300B is for the first stage of voltage gain only. Since the mu of a 300B is only 3.8, they probably could squeeze no more than 11 dB of voltage gain out of it. A typical power amp would need to have about 26 dB of voltage gain. That means that they need an additional 15 dB of gain, or even more if feedback is employed. So there must be a SS voltage gain stage in there (or an interstage transformer) followed by SS followers in the output stage to drive current into the speaker. I am assuming there are no other tubes besides the sole 300B, but I really can’t tell. So, if I am correct in my guesses, the 300B is being touted mostly for its marketing value, although it is a valid voltage amplifier. This is not to say that a competently-designed hybrid can’t sound great, only that we cannot deduce that the traditional 300B amp (SET or PP) sound character will remain here.

This great...thank you! Merry Christmas!

 

[morricab]

Extract from Enjoy the Music reviews on Analysis Audio Omega and Amphi



As much as I like full-range electrostatics, I would be the first to admit that they can't handle macrodynamics with any kick ass conviction. Even the Apogee planars of old lacked sufficient slam. It's a different story with the Omega. But there's a catch… they clearly need a lot of power.
."

Big Acoustats had slam...big waves of bass? Check... More than I heard from Divas or Full Ranges. Yes I too have heard at length the system in Frankfurt...came away disappointed as it sounded cold and lacked focus.

Not sure I would call some pieces in that system nothing exotic though. Rare Sphinx PJ16 amps (less than 10 pairs made I believe) and a Nak TX1000 auto centering TT.

 

[Brian Beck]

Some of you requested that I keep you updated on progress with my new FRs. I started by using the system in its stock configuration, with passive crossover and using the interface boxes with their transformers for bass and for midrange. I biamplified with four channels of 250 watt ARC tube amplification using their 4-ohm taps. That actually works pretty well, but erring on sounding overly ripe in the bass. Impressive, but big-bottomed.

So then I skipped the bass transfomer and directly drove the ~1.8 ohm woofer panels from the tube amps. I tried both the 1-ohm taps and the 4-ohm taps (2-ohm taps not being available, unfortunately). Direct drive completely changes the bass character of these speakers, more than I imagined it would. Bulbousness gave way to tightness. Fatness became leanness. My first reaction was that I missed the bass sock. But I am still balancing the relative gain settings between bass and MR/TW using various familiar recordings. I think if I can find the right balance, direct drive will be preferable for its tighter control and (perhaps) better pitch definition in the lower registers. Interestingly there was relatively little difference in the sound whether I was direct driving with the 1-ohm taps or the 4-ohm taps. I have to readjust the gain balance each time I change them of course. Either tap seems unflappably capable of producing high amplitudes without distress. It will take me some time to decide which bass tap to use. Both have a two-to-one impedance mismatch (from a theoretical ideal) in opposite directions, but in practice they sound more alike than different. And both sound radically different than when using the interface transformer. So, how do you like your bass? You have choices with the FR.

I also tried driving the MR/TW with 1-ohm taps knowing that the tweeter dips to about 1-ohm on top. That set-up seemed more analytical and perhaps constrained. Depth seemed to diminish. I went back to the 4-ohm tap for the MR/TW path. Of course I used the interface box for the MR/TW in all cases because the MR’s brutal ~0.15-ohm resistance requires a transformer (for now anyway). I will spend some time with this direct drive bass configuration, using the 4-ohm taps for both bass and MR/TW. I will get familiar with it on many recordings before making other changes. In my experience it pays not to change too many variables too quickly. Nevertheless this configuration does play music beautifully.

 

[christoph]

Thanks Brian for letting us join you in your FullRange endeavors
Much appreciated.

 

[RBFC]

On a side note, Harry Pearson stated that the finest system he ever heard was Dan D'Agostino's. Dan was using the Apogee Full Ranges driven by a pile of big Krell mono blocks. This was all related in a short homage to Dan D., who was just awarded an Absolute Sound award. I read this in an email today, and imagine it will appear on their website's "awards" section shortly.

Lee

 

[Brian Beck]

I will be curious to read about that in TAS. Thanks.



Here is a photo from what must be a few years later, showing a pair of Grands set up in what was purported to be D’Agostinos’s listening room. Normally driven by built-in Krell amps but here we see a collection of amps on the floor. Prototype Grands perhaps?

 

[RBFC]

I will be curious to read about that in TAS. Thanks.

View attachment 38001

Here is a photo from what must be a few years later, showing a pair of Grands set up in what was purported to be D’Agostinos’s listening room. Normally driven by built-in Krell amps but here we see a collection of amps on the floor. Prototype Grands perhaps?

I believe that was the same year Dan & Jason Bloom showed the Krell/Grand combo at a Chicago CES. I was fortunate enough to hang with them for several hours. Jason’s music suggestions are still on my playlist.

Lee

 

[bonzo75]

I will be curious to read about that in TAS. Thanks.

View attachment 38001

Here is a photo from what must be a few years later, showing a pair of Grands set up in what was purported to be D’Agostinos’s listening room. Normally driven by built-in Krell amps but here we see a collection of amps on the floor. Prototype Grands perhaps?

Built in Krell are only for woofer and tweeter, you need to biamp 2 other amps to drive the rest.

 

[bonzo75]

On a side note, Harry Pearson stated that the finest system he ever heard was Dan D'Agostino's. Dan was using the Apogee Full Ranges driven by a pile of big Krell mono blocks. This was all related in a short homage to Dan D., who was just awarded an Absolute Sound award. I read this in an email today, and imagine it will appear on their website's "awards" section shortly.

Lee

Good to hear, but not surprised at all. There is no speaker that creates the grandness and power of live music like big apogees. And that power is there even on softer passages. But it has to be driven by big monster amps IMO. There are now 4 more FRs I have noted that I would like to listen to one day. Each is driven differently with a radically different strategy. I would also like to hear the big Acoustats Brad refers to.

 

[Brian Beck]

Built in Krell are only for woofer and tweeter, you need to biamp 2 other amps to drive the rest.

Ah, yes, that’s right. That’s a lot of Krell. D’Agostino probably stood to make as much money on each Grand sold as did Bloom and Siegel!

I would probably be happy with a pair of big Krell monoblocks on my FR’s woofers. But I will insist on big tube amps for the MR and TW. Just my preference.

 

[Tango]

There are now 4 more FRs I have noted that I would like to listen to one day. Each is driven differently with a radically different strategy. .

Look to me, they are not so amps choosy as you think.

 

[bonzo75]

Look to me, they are not so amps choosy as you think.

That's assuming each FR system sounds a at a similar level.

 

[RBFC]

Ah, yes, that’s right. That’s a lot of Krell. D’Agostino probably stood to make as much money on each Grand sold as did Bloom and Siegel!

I would probably be happy with a pair of big Krell monoblocks on my FR’s woofers. But I will insist on big tube amps for the MR and TW. Just my preference.

I was using big Krell monos on the FRs, for both woofers and M/T panels. A buddy who also had FRs was using a 250W ARC tube amp for the top and it sounded incredible.

Lee

 

[Final]

Read the whole thread, all 70 pages.

Apogee FR is the speaker that got me hooked. I still do remember the sound of those speakers playing Symphony Fantastique on reference recording. Goldmund Studio recordplayer and Dynamic precision poweramps (Probably unknown to most readers, a Norwegian high end amp).

Bought the Duetta IIs but never managed to get the to sound right. Always was som metal ringing in the treble. Nothing like the FRs.

Fascinating that FR loudspeakers still live. I still want a pair of those.

I've been reading in this thread that everey restorer has his own sound. Is it possible to elaborate on the differences between resoreres house sound?

Christian

 

[spiritofmusic]

If it’s of any relevance, I’ve heard a stellar set of restored Duettas in the U.K.
If you want to feedback on them, and the restorer, send a PM to the owner, User211.