Advent modification

[Pete B]

As popular as these speakers are on this site I am hoping for more responces to my inquiry. I like my large "new" Advents enough to take exception to the comments made about them by the designer of this tape loop gizmo. IMO

Here are some responses from people who have actually tried it; I don't believe that there were any negative comments from anyone who tried it:

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=2692&view=findpost&p=66386

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2693&hl=

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=2692&view=findpost&p=74424

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=2692&view=findpost&p=73332

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=2692&view=findpost&p=72883

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=2692&view=findpost&p=73093

 

[Pete B]

picture is here:

http://img180.imageshack.us/img180/1313/bscpictorcrdc9.jpg

http://www.classicspeakerpages.net/IP.Boar...=2692&st=60

 

[archie2]

Pete thanks for those links. I have saved them and the specs to disc. I have a couple of questions.
1) Where did you get your plastic box?
2) When did speakers start compensating for BSC?

I have Polk 10A's against the back wall on a knee wall 3 feet off the floor and they image nicely. My OLA's are on 10 inch stands (actually the Polk stands) a foot and a half out from the wall with about a 5 degree tilt toed into the listener. I can hear a small difference in the soundstaging between the two pairs of speakers, the Polks are better. In another room I have a pair of Spica TC 60's on 2 foot sand filled cast iron Spica stands a third of the way into the room toed in toward the listener as per Spica directions. They throw a superb soundstage that I reference for the Polks and Advents I would love to see if your BSC Advents could disappear as well as the Spicas. So I will start gathering the components and build myself a BSC circuit box. I have 2 other pair Kloss's Advents which could also be candidates if the first Advent works out.

 

[Rybeam]

This is the photo I was talking about ;

http://img180.imageshack.us/img180/1313/bscpictorcrdc9.jpg

Is there a photo like that with the components in place ?

Yes, you do have to draw me a picture, I am an idiot when it comes to this type of stuff.

Thanks for your help Pete !!!

 

[Pete B]

I built it from low cost parts from Radio Shack: 1" X 2" X 3" plastic project box

I believe that the AR-3a roughly had BSC although it was not called BSC. Looks like the LS3/5a had it and many others, however many, even some expensive speakers do not. The Spica TC-50s also has it. More is need for speakers in the away from the wall audiophile position.

I have a feeling that you'll like the improvement with BSC. You will probably want to experiment with placement to improve the imaging as much as possible.

Pete B.

 

[Pete B]

This is the photo I was talking about ;

http://img180.imageshack.us/img180/1313/bscpictorcrdc9.jpg

Is there a photo like that with the components in place ?

Yes, you do have to draw me a picture, I am an idiot when it comes to this type of stuff.

Thanks for your help Pete !!!

Are you looking for the color codes on the resistors?
I'd suggest that you try the loaner, and use it to decide if you want a different amount of compensation.

Pete B.

 

[graywolf]

Has anyone here tried "the baffle step and HF compensation network" described on the "Classic Speaker Pages" ?

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2692


It goes on a tape monitor loop. As I have never seen this done for any other speaker I am a bit lost. Seems almost like a pre-amp or amp mod, but I am not real technical.
What do you speaker technicians think ? :scratch2:

I think that you have to notice that his Advent has been reconed, we have no idea how close to original that leaves it sounding.

Then you should notice that he has it setting 3 feet from the wall. Many small modern speakers are intended to be used that way, but almost all classic speakers were designed for and intended to be used placed against the wall. It is easy to see the difference that makes in sound, just pull your speaker out from the wall, or push it against the wall, and notice the rather large change in the sound. It does not even have to be 3 feet, just inches changes the sound.

Also people hear differently. A speaker that sounds great to me may sound awful to you and vis versa. That is why there is nothing that can be called a perfect speaker. So if you like your Advents, then ignore what he or anyone else says, you are the one listening to them.

 

[Zilch]

A notch would help, but I believe that full BSC better corrects the two major issues, and one minor. That screaming peak, a slight boxy quality, and a lack of very high end extension.

I'm not so sure about the "screaming peak" part:

Background:

1) The first image was linked by Pete B on CSP as representing the frequency response of the Small Advent, originally published by High Fidelity magazine in the '70s, and attributed to CBS Labs.

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=2692&view=findpost&p=66807

AK member Jackfish posted the same image here as representative of "Advents" more generally, based, presumably, on the oft-stated maxim that Large Advents and Small Advents have essentially the same frequency response, merely different efficiencies.

http://audiokarma.org/forums/showthread.php?p=1679375#post1679375

AK member Grateful challenged the curves as non-representative of production Advents four posts later:

http://audiokarma.org/forums/showthread.php?p=1679503#post1679503

2) About a year ago, Stereophile published a new, modern, look at the Small Advent loudspeaker, with measurements by John Atkinson:

http://www.stereophile.com/historical/506advent/index4.html

The second image is Small Advent frequency response as reported by Atkinson.

The 1.2 kHz peak is not there. Note also the boomy bass in 2-pi alignment, (nearfield woofer measurement,) upon which I have commented elsewhere in this forum. In 4-pi alignment, BSC would serve primarily to restore the "boom" lost with boundary separation.

3) And finally, I measured The Advent Loudspeaker - Utility, also know as Original Large Advents, last month. To the best of my knowledge, I'm the only one to have done this and published the results in the nearly 40 years since the product was introduced. I would certainly be pleased to see anything anyone else might have done posted here, either in confirmation of, or conflicting with, my work with Advents:

http://audiokarma.org/forums/showthread.php?p=1937162#post1937162

It is easily seen that my findings on Large Advents are substantially similar to those recently published for Small Advents by Stereophile.... :yes:

For a guy that dislikes Advents so much, Zilch has an odd tendency to comment in every new Advent thread. I've often wondered what compels a person to do such a thing.

Seconded. :thmbsp:

Thirded....................R1:yes:

Get it, now?

 

[archie2]

Pete, you listed R2 as 4.3K. I cannot find a 4.3K resistor at Radio Shack. Can a 4.7K be substituted? Thanks.
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2692&st=60&p=72883&#entry72883

 

[Zilch]

Pete: Post the transfer function of your BSC circuit here, please.... :yes:

 

[Rybeam]

All the talk of Advents the last couple of months has been great. It started at roughly the same time I lucked into a pair of NLA hog noses. I have admired the looks of these speakers since their introduction. I was in high school and remember how cool the speakers looked and how funny their little receiver was.

Starting in the late '80s I started the still active discovery of the stereos I could not afford when new on the cheap. I have had at least two pair of Baby Advents, a pair of Prodigy two way tower, and a New Advent in the smaller utility cabinet. Currently I have a pair of Advent 3's [not being used] and of course the a fore mentioned NLA's.
Each time until the NLA's the Advents I got were not capable of replacing anything I was using so I sold them. The small New Advents did stay in A-B mode against my keepers for a couple of months. It really came down to the lack of real veneer and the lesser dollar value to the others that led to selling them. I was so impressed with their performance I started watching them on e-bay a bit and hoped to try them some day. April this year I find a pair NLA's needing refoamed and two weeks later a Advent 300 receiver! I am a bit anal about my stereos, so I had the foam replaced by a local speaker only repair shop.

This time the the Advents win a place in my second system. I am using them instead of a pair of Bozak DMS2500 that have held the job for about four years. I figure roughly 10 challengers [including a nice pair of HPM100's] have been ran off by them. To be fair I bought the Bozak's from a local newspaper ad and paid $150 for them [retail $900 in '86]. It was going to take a heck of a Thrift Store find to run them off. The sound between Advents and the Bozaks is extremely close. Smaller size and looks is what won the job, and no the Bozaks are not going anywhere yet.

As with all my speakers I have them sitting on 3 pieces of rubber/cork/asphalt industrial isolation material, the one in back is 1 inch tall have two 1/4 inch in front. Last I knew Grainger still sells it in sheets. Speakers never touch the wall, I feel isolation of the speakers is very important. I have the Advents on top of bookshelves 4 ft high, about 10 feet apart, nearest corner 3 feet away and my ears are 16 feet center back. A laser pointer is used to figure toe in, tweeters hit about hat high on me. Carpet,acoustic tile ceiling a pretty soft room. Compared to the living room,everything sounds better in this room. Children move out I will move main system into this room. Just for fun I cut a felt piece to cover the face of the tweeter to help imaging, at least I read it works.

I posted earlier I was happy using the Advent receiver for power. It took a week or so to decide the sound was getting thin at edges of my normal listing level and up loud was harsh. I do however like the tuner, the pre-amp has bass and treble controls that have a board effect and the phono section has a reputation as very good so I am using it as a pre-amp tuner. I am using a Pioneer SA-7500 40 watts per channel the harshness is gone, they purrrr on Pioneer power. I have an AR ES-1 with an Audio Technica OC9 moving coil cartridge going thru a Marcof step up amp that uses two 9 volt batteries. The CD is a 1992 Arcam Alpha their first CD player made in the UK and a Yamaha KX-530 cassette deck.

So that is my journey to Advents and my handling of the set up. In my experience they are the best speakers their size I have ever owned.


BACK TO the real subject. Can the BSC be put between the pre amp and power amp ?

I would really like to see a cross over design that addresses the same issues as the BSC. Thanks all for your continued interest in a fine speaker design the appears to be having a bit of a rebirth !

Happy Forth of July All !!!!

 

[Zilch]

BACK TO the real subject. Can the BSC be put between the pre amp and power amp?

Put a parametric EQ in there, and tweak away for the rest of your life....

I would really like to see a cross over design that addresses the same issues as the BSC.

You don't have a BSC issue the way you are using them.

I would like to see someone redevelop the Advents using a suitable modern tweeter. Not my gig, basically. I did it with AR4s to an apparent chorus of yawns here.

"The Advent's tweeter is a total underperformer compared with modern designs...." according to Stereophile's John Atkinson.

I'm working to resolve the Advent mirror-imaging and low crossover frequency problems using a small PT waveguide and compression driver in place of the tweeter.

Either way, they're not Advents anymore, and, as I observed earlier, I don't see there're much in the way of benefit to be acheived doing less....

 

[Rybeam]

Zilch I wonder about a design that capitalizes on the strengths of stacking. A single tower type design using two Advent woofers and a tweeter of some type, a ribbon type maybe. A New New Advent.

 

[Zilch]

Zilch I wonder about a design that capitalizes on the strengths of stacking. A single tower type design using two Advent woofers and a tweeter of some type, a ribbon type maybe. A New New Advent.

I have not yet discovered any exploitable benefit to stacking.

There's more to employing double woofs than sticking two of them in the same box; they've got to be "managed" to play well in a system with a HF driver or tweeter.

The Advent woofer has its own problems. There are better modern designs available to work with.

Again, we're back to the same place: Different tweeter, different woofer, different box, and we're no longer talking about anything Advent anymore.

Leave them be. They are what they are; enjoy that or move them on. There would appear little more to be done with them that doesn't make them into something else....

 

[sealy]

Amen. I believe one should keep everything as original as possible with vintage speakers. Even taking into consideration the aforementioned faults of the Advents, their virtues far outweigh their flaws.

 

[Rybeam]

I stack your Amen ! Yep, I never change anything unless it's broke. If I modifie, I do it in away that is easily reversed.
Zilch, Pete I appreciate your efforts. Very interesting stuff.

 

[Zilch]

I stack your Amen !

:nono: No STACKING!! :nono:

​

 

[Pete B]

I think that you have to notice that his Advent has been reconed, we have no idea how close to original that leaves it sounding.

Then you should notice that he has it setting 3 feet from the wall. Many small modern speakers are intended to be used that way, but almost all classic speakers were designed for and intended to be used placed against the wall. It is easy to see the difference that makes in sound, just pull your speaker out from the wall, or push it against the wall, and notice the rather large change in the sound. It does not even have to be 3 feet, just inches changes the sound.

Also people hear differently. A speaker that sounds great to me may sound awful to you and vis versa. That is why there is nothing that can be called a perfect speaker. So if you like your Advents, then ignore what he or anyone else says, you are the one listening to them.

The recone job, while not perfect did use the correct cone, so it was not a major issue. I have since then replaced the reconed woofer with an original woofer purchased from e-bay, and the sound or conclusions about BSC did not change in any significant way.

I expect people looking for the best sound and imaging to space their speakers out into the room, then BSC is needed even more. Think about it though, out in the room is very similar to up on a shelf with the woofer being close to one boundary.

Why should they ignore what others say, when most of the others did not have reconed woofers? The fact is that it sounds remarkable.

And once again I'm wasting my time here, I really don't care, try the damn thing.

 

[Pete B]

:nono: No STACKING!! :nono:

​

I've not tried stacked Advents, and I'm fully aware of the lobing and comb filtering effects. I'm also able to hear defects in the midrange such as notching when they're present in both the on axis and reverberant power response. I do place strong weight on the on axis response, however, it is possible that the power response helps with regard to stacking Advents. I've not lived with stacked Advents yet, so I will not comment myself, however I will put some faith in those who's ears I trust that it works well enough to be satisfying. Zilch, you may rely only on measurements for your own purposes, but I use both, measurements and in room listening to draw my conclusions. You also have to consider psychoacoutic factors, and the fact that source material is far from perfect.

 

[Pete B]

I'm not so sure about the "screaming peak" part:

Background:

1) The first image was linked by Pete B on CSP as representing the frequency response of the Small Advent, originally published by High Fidelity magazine in the '70s, and attributed to CBS Labs.

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=2692&view=findpost&p=66807

AK member Jackfish posted the same image here as representative of "Advents" more generally, based, presumably, on the oft-stated maxim that Large Advents and Small Advents have essentially the same frequency response, merely different efficiencies.

http://audiokarma.org/forums/showthread.php?p=1679375#post1679375

AK member Grateful challenged the curves as non-representative of production Advents four posts later:

http://audiokarma.org/forums/showthread.php?p=1679503#post1679503

2) About a year ago, Stereophile published a new, modern, look at the Small Advent loudspeaker, with measurements by John Atkinson:

http://www.stereophile.com/historical/506advent/index4.html

The second image is Small Advent frequency response as reported by Atkinson.

The 1.2 kHz peak is not there. Note also the boomy bass in 2-pi alignment, (nearfield woofer measurement,) upon which I have commented elsewhere in this forum. In 4-pi alignment, BSC would serve primarily to restore the "boom" lost with boundary separation.

3) And finally, I measured The Advent Loudspeaker - Utility, also know as Original Large Advents, last month. To the best of my knowledge, I'm the only one to have done this and published the results in the nearly 40 years since the product was introduced. I would certainly be pleased to see anything anyone else might have done posted here, either in confirmation of, or conflicting with, my work with Advents:

http://audiokarma.org/forums/showthread.php?p=1937162#post1937162

It is easily seen that my findings on Large Advents are substantially similar to those recently published for Small Advents by Stereophile.... :yes:

Get it, now?

Zilch, I suggest that you try BSC before trying to shoot it down with a long intellectual discourse. To be honest, I trust that old published curve much more than yours or Stereophile's measurements. It was done in a large calibrated anechoic chamber with LF correction by professionals at CBS labs years ago. I would call Advent bass ripe, but not boomy, but hey it's a subjective thing so call it as you will. Advents have strong output down to the low 40s and therefore are sensitive to room placement, often the issue is the room not the speaker. Sure take a speaker that is 6 or 10 dB down at 40 and it will be much more tolerant of room cavity mode resonance issues in that frequency range. Properly placed Advents do not have boomy bass, but will provide that kick in the chest feeling.

Let's talk psychoacoustic effects, the threshold of audibility for response differences is about .1 dB if it is over a wide enough bandwidth and under the right A/B conditions. 1 dB is usually easily heard. 3 or 6 dB over the bandwidth shown in a region where our hearing is most sensitive, yes is screaming IMO.

Do you listen at realistic levels? If not the equal-level loudness contours should be applied, and that peak is the opposite of what is required.

Are you familiar with the BBC dip, this is another factor concerning the difference between measured response and in room, phsychoacoustic considerations.

BSC may be correcting for more than just BSC, what I can say is that it is a very significant improvement.

Pete B.