The New Advent Loudspeaker Review (Vintage Speaker)

[Keith Conroy]

Here are the complete TS parameters for the A25 woofer. Note the extremely high Vas and Qts.

View attachment 143669

Interesting.......!! Thank you again, for your time & follow through on the measurement data provided

 

[mhardy6647]

Also, there were two final prototypes; one with a copper voice coil and one with an aluminum voice coil (The aluminum one was the winner), and the semi-finalists were 4Ω but Dyna had this changed to 8Ω for the production version.I think this was either from the VTV article oron the now-gone 'Unofficial Dynaco Homepage' site.

FWIW, most of Greg Dunn's page(s) can be found via the Wayback Machine.
e.g.,
https://web.archive.org/web/20050215020226/http://home.indy.net/~gregdunn/dynaco/
and
https://web.archive.org/web/2008022...regdunn/dynaco/components/speakers/index.html

 

[Aperiodic]

Man that site is hard to use, but thanks for the tip, I collected both those pages. Now if I can only find the 'Dynaquad' paper I've been looking for forever. And thanks to Greg Dunn, RIP presumably, he maintained his site for many years.

 

[Dennis Murphy]

FWIW, most of Greg Dunn's page(s) can be found via the Wayback Machine.
e.g.,
https://web.archive.org/web/20050215020226/http://home.indy.net/~gregdunn/dynaco/
and
https://web.archive.org/web/2008022...regdunn/dynaco/components/speakers/index.html

Interesting. The discussion on the second link makes it sound like it was the stuffing inside the main box, not in the vent, that was adjusted on the assembly line.
"The production was set up that a large excursion, a 5 Hz square wave was fed into the unit, and layers of fiberglass were inserted into the body of the box, until there was minimum overshoot, which translated into maximally flat response at 50 Hz and below."

 

[TimmyO]

I have had my pair of New Large Advents for a few years now. I have had them fully serviced, re coned, capped and new crossover. I have also sanded them back and re oiled the walnut veneer and they look excellent. My NLAs sound great. I only really listen to vinyl tho. Mostly 50’s & 60’s rock and jazz music. I play punk music too. I’ve thought about adding subs, but I’m pretty happy with the sound so haven’t bothered. However when I play the same album via lossless digital file through my DAC I must say it sounds thin, tinny and horrible. So I wonder if this is just the difference between vinyl and digital..? Or perhaps the NLA were just designed to sound right for the popular playback of the time being vinyl records? I have found that adding better speaker cables, power supplies, dampening vinyl mats, vinyl weight, speaker placement, etc has done wonders to improve imaging and bass response. And I only always listen to them with dust covers off.

 

[Aperiodic]

Interesting. The discussion on the second link makes it sound like it was the stuffing inside the main box, not in the vent, that was adjusted on the assembly line.
"The production was set up that a large excursion, a 5 Hz square wave was fed into the unit, and layers of fiberglass were inserted into the body of the box, until there was minimum overshoot, which translated into maximally flat response at 50 Hz and below."

That was poorly worded for sure.

 

[rdenney]

I have had my pair of New Large Advents for a few years now. I have had them fully serviced, re coned, capped and new crossover. I have also sanded them back and re oiled the walnut veneer and they look excellent. My NLAs sound great. I only really listen to vinyl tho. Mostly 50’s & 60’s rock and jazz music. I play punk music too. I’ve thought about adding subs, but I’m pretty happy with the sound so haven’t bothered. However when I play the same album via lossless digital file through my DAC I must say it sounds thin, tinny and horrible. So I wonder if this is just the difference between vinyl and digital..? Or perhaps the NLA were just designed to sound right for the popular playback of the time being vinyl records? I have found that adding better speaker cables, power supplies, dampening vinyl mats, vinyl weight, speaker placement, etc has done wonders to improve imaging and bass response. And I only always listen to them with dust covers off.

Hmmm. The Advents are one speaker that needs the grill cloth to help with dispersion and directivity, from what I've read and based on my experience.

And subs are the one thing Advents don't really need. What they need is treble extension and a better mid-range.

But I used Advents for 44 years, and never have I noticed that digital sources sound thin, tinny, and horrible compared to vinyl. But to make that comparison, first and foremost the levels must be matched--if the DAC is putting out a lower signal than the phono preamp, it will be lower in volume which can make it sound thin. Even level differences too small to notice as such will affect our perception of it. The only time I ever noted a thin sound from my Advents was when I had inadvertently wired one one of them out of phase. My NLAs have good drivers and I have restore the crossovers in them, too.

It is certainly true that Advents were designed to sound good given the popular sources of the day. The original OLA had a more rolled-off top octave than did the NLA, which Kloss cranked up a bit specifically to account for source material that had more useful information in the top octave.

As to those other things you did, are you able to demonstrate that those effects you noted as being "wonders" could be detected when you didn't know they had been done? The mind plays tricks on us. A weight on my records would eat up the suspension of my turntable and bottom it out. That might make it pick up vibration from the furniture, which might increase bass microphonic resonance, but it seems to me that would be a bad thing. Damping mats might help a table avoid microphonics, but then you really have to put it in a vacuum chamber to avoid some acoustic feedback from the speakers (which will emphasize bass, but unnaturally). All there is to get from Advents (or any other speaker) is had from copper wire of sufficient gauge, which for Advents doesn't need to be larger than 14-guage unless your speakers are further away from your amp than usual by quite a margin. I found zero difference between 12-guage speaker cables and 16-guage zip cord--and I conducted that test for myself in the 80's when I was able to hear the 18-KHz flyback transformer of computer monitors.

We hear claims such as yours routinely, but any form of controlled testing to demonstrate that the perceptions are repeatable, reliable, and unaffected by biases both conscious and unconscious never seems to accompany them. Thus, folks here are skeptical, because many have done those tests and they have not found the correlations implied by those claims.

Imaging is about placement, mostly. Gordon Holt, one of the progenitors of the use of that adjective and one who gave that feature higher attention than most other reviewers, didn't have any trouble with imaging using Advents. Placement matters. When I've had good placement with Advents, I've had good imaging. When not, I haven't. Advents usually won't do quite as well as later designs, simply because the tweeters are not centered, which means the tweeter sweet spot isn't in the same place as the woofer sweet spot, and the mid-range where both drivers are overlapped gets muddied a bit therefore (and there is also the phasing through the crossover region). My Revels provide better imaging, but they were designed with excellent directivity and better crossovers based on what the industry has learned since the Advent days.

Rick "anything that does 'wonders' ought to easily hold up to blind testing, and, for that matter, measurements" Denney

 

[mhardy6647]

That was poorly worded for sure.

Doubtless written by marketeers

 

[rdenney]

That was poorly worded for sure.

Is there a difference between the "main box" and the "port"? My sense of these was that the port was just an opening into the main box. Probably, the stuffing started out outside and ended up inside, and that's what he meant.

Rick "engineers often don't choose words with the expectation of high-precision ex post facto analysis" Denney

 

[rdenney]

I just had a silly thought, absolutely on-topic.

I've read of those who replace the Advent tweeter with a horn ("econowave" over at AK), but that requires the use of a saw on the Advents and I'm too sentimental to cut 'em up.

But it occurs to me the following: Advents have a great woofer (foam rot notwithstanding) and, by modern standards, a mediocre mid-tweeter. Has anyone ever just disconnected the tweeter and used Advents as subs? The woofers might be better for not being crossed over so high, for one thing.

Not for movies, but for music. No need for infrasonics, and cross 'em at 80 Hz or so.

Hmmmm. Hmmmm.

Rick "who has an extra PEQ that could be used as a crossover" Denney

 

[Aperiodic]

Or perhaps the NLA were just designed to sound right for the popular playback of the time being vinyl records?

In a word, yes.
There are (at least!) two approaches to voicing any transducer:

• Aim for dead flat and let the chips fall where they may: In headphones, this approach is exemplified by the AKG K701, whose sound is often criticized as 'sterile'; or
• Design taking anticipated source material into account, which will yield a response that is not strictly 'flat'. In headphones, think HD650.

In loudspeakers, the second approach was the one explicitly taken by Advent per their literature. This is something that changed dramatically with the arrival of digital source material. Not easy to make a speaker that sounds its best on both. Advent voiced for the source material of its time, which was 100% analog. So there may be unexpected results using source material with characteristics not anticipated at the time of the original design. (Advent hinted at this in discussing the revised tweeter design in the 'New' version.) This isn't to say that good digital can't 'sound good' on older speakers though.

 

[rdenney]

In a word, yes.
There are (at least!) two approaches to voicing any transducer:

• Aim for dead flat and let the chips fall where they may: In headphones, this approach is exemplified by the AKG K701, whose sound is often criticized as 'sterile'; or
• Design taking anticipated source material into account, which will yield a response that is not strictly 'flat'. In headphones, think HD650.

In loudspeakers, the second approach was the one explicitly taken by Advent per their literature. This is something that changed dramatically with the arrival of digital source material. Not easy to make a speaker that sounds its best on both. Advent voiced for the source material of its time, which was 100% analog. So there may be unexpected results using source material with characteristics not anticipated at the time of the original design. (Advent hinted at this in discussing the revised tweeter design in the 'New' version.) This isn't to say that good digital can't 'sound good' on older speakers though.

Well, the faults of Advents are not in the range where digital sources are really that different from analog sources. The rolled-off top octave likely helps digital stuff sound more like analog stuff, and the strong bottom end gets used by both (although to greater effect with sources that have better channel separation in the bass).

It's true that a lot of pop records (including rock albums in my collection) had a smiley-face EQ, and the Advents will help with that. The tight bass and the rolled-off high end will diminish that fault. But Advents are especially good (relatively) with classical music not mixed that way, and they are particularly good about sustaining instrument timbre.

I certainly enjoyed listening to CD's through Advents, without noticing any particular weakness.

Rick "whose first CD player arrive one-quarter of the way into his long Advent ownership" Denney

 

[Aperiodic]

I just had a silly thought, absolutely on-topic.

I've read of those who replace the Advent tweeter with a horn ("econowave" over at AK), but that requires the use of a saw on the Advents and I'm too sentimental to cut 'em up.

Blasphemy!!!

But it occurs to me the following: Advents have a great woofer (foam rot notwithstanding) and, by modern standards, a mediocre mid-tweeter. Has anyone ever just disconnected the tweeter and used Advents as subs? The woofers might be better for not being crossed over so high, for one thing.

Not sure what you're suggesting here... The Advent crossover was 1500Hz (same as the A25) which was lower than most two-way systems at the time. Judging from Amir's testing, it may have struggled a bit at the top of its range, but 80 Hz?

 

[Keith Conroy]

Man that site is hard to use, but thanks for the tip, I collected both those pages. Now if I can only find the 'Dynaquad' paper I've been looking for forever. And thanks to Greg Dunn, RIP presumably, he maintained his site for many years.

I went to the Dynaco link, WOW very cool. I also want to say I'm proud and impressed by this whole groups post's and detective work. As a group we have a fair amount of horsepower to look into things! I have been to audio sites where people want to just argue? They go to all ends to prove they must be right?? As an example they want to argue about "HOW WHITE THE COLOR OF WHITE IT"?? I have found on this site we can disagree in a civil manor and move on. If someone disagrees many try to post facts to back things up! I love the science of audio! Thanks to Amir for developing this site!

 

[rdenney]

Not sure what you're suggesting here... The Advent crossover was 1500Hz (same as the A25) which was lower than most two-way systems at the time. Judging from Amir's testing, it may have struggled a bit at the top of its range, but 80 Hz?

Well, my current speakers are already very good down low, but I detect a bit of boominess that is probably a room mode they found. But they are ported, and I still prefer the tight bass sound of the Advents. I also hear that subs are useful for controlling room modes.

Rick "just thinking out loud" Denney

 

[mhardy6647]

I went to the Dynaco link, WOW very cool. I also want to say I'm proud and impressed by this whole groups post's and detective work. As a group we have a fair amount of horsepower to look into things! I have been to audio sites where people want to just argue? They go to all ends to prove they must be right?? As an example they want to argue about "HOW WHITE THE COLOR OF WHITE IT"?? I have found on this site we can disagree in a civil manor and move on. If someone disagrees many try to post facts to back things up! I love the science of audio! Thanks to Amir for developing this site!

Some of us... well... have no lives.
Actually I do have a life, but it's mostly pretty boring... and I learned to do database searching back in the days of Telenet and Dialog.

Now, I'll let you in on a little secret -- here's the world's best one-stop shopping for most matters radio and hifi audio... in case you don't know about it...

https://worldradiohistory.com/

 

[Aperiodic]

This has been a very interesting thread, from the initial vintage loudspeaker review to what is probably the first T-S analysis of the A-25 (thanks Dennis). As I said before, these two speakers seem forever linked in audio history, kind of like Ali and Frazier, Lewis and Martin, Abbott and Costello...

 

[Dennis Murphy]

Is there a difference between the "main box" and the "port"? My sense of these was that the port was just an opening into the main box. Probably, the stuffing started out outside and ended up inside, and that's what he meant.

Rick "engineers often don't choose words with the expectation of high-precision ex post facto analysis" Denney

The stuffing in the aperiodic vent is completely separate from the layers of fiberglass in the main cabinet. So they were either adjusting the former or the latter. Or neither.

 

[Keithdd]

None of the Home Depots in Calgary will cut MDF. An employee even asked a manager if he could and was told no. So I asked a carpenter client to do a few cuts and was told he doesn't work in MDF at all anymore because his industry recommends against it because of the risk of cancer.

https://www.theguardian.com/uk/1997/sep/21/antonybarnett.theobserver#:~:text=When MDF is cut, sanded,inhaled deep into the lungs.

Weird. My home depot on 130 Ave SE Calgary cut them with a smile. But everyone wearing masks due to Covid.

 

[Aperiodic]

The stuffing in the aperiodic vent is completely separate from the layers of fiberglass in the main cabinet. So they were either adjusting the former or the latter. Or neither.

Back to that?!? Except for one poorly written paragraph on one third party website, all available sources specifically indicate that the stuffing in the port was adjusted to achieve the objective. I can see it now: Put the interior screen on the inside front panel before installing the front panel as the last part of cabinet assembly. Install drivers. Stuff some fiberglass in the port (I bet that after the first couple hundred thousand, they could probably get pretty close on the first try.) Connect up the system as described and feed it the stipulated signal as described at length in multiple sources. Staple the front screen on. Attach the grille cloth. Next!

Why are you so resistant to the idea that Dyna actually did what they said they did? The whole procedure probably took less than two minutes after you'd done it a few times. It probably took less time than most builders put in on final QC checklists. Back then, people- on a lot of things- actually took time to get things right rather than trying to squeeze the profit margin another 0.03%.