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Pete B

Early Advent History From an Engineer on the R&D Team

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I worked over 10 years ago with an analog engineer who had

previously worked at Advent in the early 1970s. We often had

lunch together where we chatted about what went on behind

the scenes.

I ran into this friend coming out of the Grand Hyatt in NYC

recently when the HE 2007 show was going on. I have to say

that I was surprised to read on this forum that some believe

that Andy Kotsatos designed all the Large Advents. The early

Large Advents have the writing on the back "Designed By Henry

Kloss" and I believe it. I posed this question to my friend

when I ran into him, and this was his response in a later email,

posted with his permission:

=================================================================

"Regarding your Advent query - the way I remember it happening was that Henry Kloss had a noncompete clause when he left KLH that prevented him from peddling loudspeakers for some specified period of time. According to legend, he designed the Advent loudspeaker and filled a couple of trucks with the things. On the day that the noncompete clause expired, the trucks rolled out to the stores! It is entirely possible that these very first loudspeakers were entirely of Henry's design."

"By the time I arrived at Advent R&D in the early 70's, I vaguely remember there being some brouha about the loudspeaker not sounding right. One of my first tasks was learning how to run the General Radio stripchart equipment, and I wound up running lots of loudspeaker and crossover curves. Bruce Gregory, the lead electrical design engineer, wound up redesigning the crossover and Andy did the voicing by tweaking the parameters. There was a lot of back-and-forth (and lots of curves) getting the thing right. They also made a design change to the tweeter, but I don't remember the details. If anyone has an early Advent Utility, most likely it is one of these revised units, since they were the ones that sold in volume."

"Personnel involved with auditioning the Advent loudspeaker product line most likely were Andy, Bruce, Henry, Stan Pressman (head of marketing), and Joe Hull."

=================================================================

Comment: We have only identified 2 early versions of the Large Advent

what I call the Rev1 16/16 uF, and the Rev2 16/8 uF, what I call Rev3 is

the New Advent. The Rev1 that I worked on was from 1972, and I have seen

a very early version without the metal mesh screen over the tweeter. This

earlier version might also have the crossover that was "not sounding right".

There is also the addition of bulb dye to

the tweeters to seal the sometimes porous paper cone. I have never

seen a natural paper color Advent tweeter but they probably exist.

The Rev1 and Rev2 versions are the ones that sold in large volumes.

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Hi Vern,

Thanks for your comments.

Thinking about this more, my friend says he arrived

there in the early 70s, which could be 1972-73, when

the revision from the Rev1 to Rev2 crossover was done.

I would agree that something doesn't sound right

especially in the extended position with the Rev1

design, however, I don't recall any changes in the

tweeter from Rev1 to Rev2. There was the tweeter grille

and use of bulb dye from the very early to Rev1 change,

so I think more likely this was it.

Perhaps, I'll send him the email from Andy Kotsatos where

he mentions the bulb dye on the tweeter is mentioned.

My friend also mentioned during our conversation that an

MIT grad student did most of the Small Advent work, again

with Henry's input and oversight. Really, it is just a box

reduction, and new woofer.

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>Really, it is just a box

>reduction, and new woofer.

I guess for a student of MIT the word "just" is appropriate but for this Average Joe, the thought of designing a new woofer, especially *that* one and its associated xover, is quite intimidating!

*****************************************

Fun factoid: around the late 70s someone at Radio Shack's speaker division must have been inspired by that woofer because one of their better speakers (a 3-way) used a 10" sealed woofer with a dust cap almost identical to the Smaller's cap. As a 12 year old kid just getting into audio I was always fascinated by that huge wrinkled cap (and the funky 1/4" gray ring of sandpaper-like coating around it). IIRC another Realistic speaker used this same heavy-looking woofer in a two-way system with a 1" soft-dome tweeter, but this time as a passive radiator coupled with an 8" active woofer (passive radiators were another mystery feature for me at the time). That same eight incher was also used by RadShak in a transmission line enclosure.......but that's another forum! :^)

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I have known Andy Kotsatos quite well, both professionally and personally, for many years. I have the utmost respect and admiration for his accomplishments and contributions to our industry.

What follows are excerpts from two earlier posts of mine (around 2002 or 2003) that may shed some interesting light on his involvement in voicing/designing the Advents and the Advent design philosophy. This comes from my direct association with him, and the many conversations we had about the "old days."

(Note: Both Andy and Moses Gabbay have retired from Boston Acoustics since my original posts.)

First post:

Andy's dad worked in the kitchen of a famous NY hotel as a busboy and helper. He was "vertically challenged,” and the kitchen staff, mostly French-speaking, called him Le Petite. That name stuck until 1994, when Andy had had enough and went back to his Greek roots, re-assuming his original family name of Kotsatos.

Andy worked retail at a Harvard-square (Cambridge MA) hi-fi store in the early 60's that featured KLH. He then went to work at KLH as a product manager, where he met Henry Kloss. He went with Henry to Advent in the late 60's and helped Henry voice the original Advent and Smaller Advent. Andy was totally responsible for the design of the New Advent loudspeaker, which was a very nice product.

When Advent ran into financial trouble in the mid to late 70's (remember, Henry founded Advent as a vehicle to develop and market big-screen TVs; the speaker end of Advent was just supposed to supply the cash flow), it changed ownership, and things went downhill very fast. Andy and Advent's credit manager, Frank Reed, saw the handwriting on the wall, and they left Advent to start Boston Acoustics in 1979.

Their timing was perfect. Frank was a business genius who carefully guided a bunch of engineer/hobbyist store owners in the proper ways to merchandise and run their businesses profitably; Andy was the product designer, and came up with several great products in the classic Advent tradition. Very shortly after the company's founding, Moses Gabbay, a top AR engineer, joined BA. Today Andy is Chairman of the Board and Moses is CEO. Frank passed away in November 1996, but was actively involved right up until his death.

Andy never worked at AR. He has always considered them to be the "enemy," like a Red Sox-Yankees or Ali-Frazier rivalry. If you run into him at a CES show, a BAS meeting, or some other industry gathering, his passions and memories of the heated days of the 60's-70's speaker business are easily--and fascinatingly-- elicited.

Next post (partial)—

The fundamental reasons for the difference in the sound of Advents and AR’s in the late 60’s-early 70’s era had to do with the very different design philosophies between the two companies.

KLH/Advent/Kloss, as Tom pointed out, relied mostly on subjective measurements and the evaluation of the speaker’s octave-to-octave balance. Henry believed that people responded to sound in broad frequency blocks—octaves—and if the relative balance from one octave to the next were correct, the device, whether it was a speaker, a compact stereo system, a radio, or whatever, would be pleasing and satisfying to the end user.

For the original Large Advent, Henry did the design work on the drivers and enclosure in 1968-1969, but gave an early pre-production prototype to his associate and protégé, Andy Petite (who later changed his name back to his original Greek family name, Andy Kotsatos after he founded Boston Acoustics), along with a 10-band graphic equalizer.

“Here, take this home, and make it sound the way you like it. Mark down the settings of the EQ when you’ve got it right, and then we’ll talk.”

So he did, and then he and Henry compared notes. That’s how the Large Advent was voiced—by Andy getting its octave-to-octave balance to be satisfying and convincing on as wide a range of program material as possible. It was hugely successful, obviously, because the speaker sold extremely well—although there were pure marketing decisions that contributed to the speaker’s success as well, which we’ll explore later.

Henry and Andy also believed in the importance of smooth on-axis response as a starting point for good loudspeakers. They didn’t place much importance on power response at all.

Villchur and Roy Allison believed much more in the power response approach. Very simply stated, power response is the total energy radiated by a speaker, measured in the reverberant field. It is essentially a summation of all the on-and off-axis “frequency responses” of the speaker, including the room reflections. In an energy response measurement, the on-axis response of the speaker is the strongest component of the measurement (because it is the axis on which the speaker puts out its greatest energy), but it is only a part of the total measurement...

Steve F.

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As someone who owns Boston Acoustics speakers and recommends them to anyone who asks (and also used to own Advents for 14 years and now a pair of Smaller Advents), this is an interesting discussion.

>>> When Advent ran into financial trouble in the mid to late 70's <<<

Do you know why this occurred? This is surprising, being that the Large Advent was one of the most successful loudspeakers of all time.

>>> it changed ownership, and things went downhill very fast. <<<

I think I might be entering touchy territory here, but what aspects of Advent went "downhill"?

>>> “Here, take this home, and make it sound the way you like it.

Mark down the settings of the EQ when you’ve got it right, and

then we’ll talk. <<<

Holy cow, can you imagine a speaker company doing this now? While I think highly accurate/100% scientifically-researched speakers have their place (recording studios for one) in the home environment they can sound really sterile and uninvolving....which is why I think so many home speakers sound like this now i.e. too many speakers being designed totally(?) "in the computer" to save on R&D costs rather than with help from the ears.

>>> Henry and Andy also believed in the importance of smooth on-axis response as a starting point for good loudspeakers. They didn’t place much importance on power response at all. <<<

I always wondered why these two company's speakers sounded so different from each other.

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My friend also spoke very highly of Andy K. and I don't think there is any disagreement, he did say that Andy K. fine tuned the voicing on most of the early Advents.

I am completely of Greek heritage and people like Andy Kotsatos, I'm sure, make all Greeks feel proud. I don't think I'll return to my family's original name though.

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Thanks for the fascinating thread you guys (he says while listening to his triple stack of original Advents :^)

Doug

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Hi Doug,

Nice to hear from you!

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My friend sent me a schematic from his personal files, he says that he drew it since

he owned a pair of the Advents from that time and it is dated 26 August 1970. My

friend wrote: "The date would place it at 377 Putnam Ave., which was the

original location of the company and where I started working for them. Don't know

which value of L1 and L2 they finally settled on." So this indicates that he did start in 1970.

It is earlier than anything we've been talking about here, one member mentioned a

very early version with a 4 ohm resistor and this should be it. It is what I've called

Rev0, and it has a 16 uF main cap, with an 8 uF extended cap. The resistor is listed as 4.14 ohms.

The inductors are listed below:

L1 .149 mH, .208 mH, Q=1.6, R=.56 ohms Decrease inductor

L2 .850 mH, 1.055 mH, Q=2.0, R=2.5 ohms Tweeter shunt inductor

L3 1.42 mH, Q=14 @ 1 kHz, R=.273 ohms Woofer inductor

Note that there are two values for L1 and L2 and he states that he's not sure which value they settled on.

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Thanks Pete.

I just wrote up a rather lengthy post about refoaming that will probably bore most readers to tears but there you have it.

I have been following your measurments regarding the New Advent and variations and this is the type of information that should be made a "pinned" thread if any.

That and maybe practical applications such as refoaming/rebuilding as you mentioned in another thread.

Regards,

Doug

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Wow! I thought that the 16/8uF combination is only in the later units from sometime in 1974-1975 on!

But you say that that early schematic shows these?

That's a whole 'nuther kettle of fish because most have assumed that the early units had the 16/16 combination!

Doug

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Hi Doug,

Yes I'm sure, I'm surprised that they made the mistake of going

to the 16/16 version, but not so surprised that they went back.

My friend is very methodical so I have a lot of confidence in his

schematic, but who knows how many were shipped with that. He said

himself that the later design(s) was the high volume seller, what

we've called Rev1 (16/16) and 2 (later 16/8).

The very thin wire inductors in Rev 0 and 1 were also a mistake, IMO.

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Pete:

If you ever get another chance to talk to Andy K., could you ask him if it was general practice back then to 'voice' capacitors when the designer/developer was in the final stages of identifying specific components to purchase in quantity for crossovers going into a new model.

Thanks,

It's all about the music

Carl

Carl's Custom Loudspeakers

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Hi Carl,

My friend is not Andy K., he wishes to remain anonymous.

I'll ask him next time we exchange e-mail.

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>Thanks Pete.

>

>I just wrote up a rather lengthy post about refoaming that

>will probably bore most readers to tears but there you have

>it.

>

>I have been following your measurments regarding the New

>Advent and variations and this is the type of information that

>should be made a "pinned" thread if any.

>

>That and maybe practical applications such as

>refoaming/rebuilding as you mentioned in another thread.

>

>Regards,

>Doug

Hi Doug,

I did enjoy reading your thread, good to see you get them in perfect working order. I think Mark is probably too busy to worry about pinning threads, perhaps he would make you a moderator with that ability, that would be nice. Certainly, how to refoam, where to get foam, etc. should be pinned, grille cloth discussions, etc. etc.

I'm having trouble finding my own threads, LOL!

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Guest Synthsayer

Thanks a bunch Pete,

I have a pair of the Advent V2 with the date May 1, 1974 stamped onto tweeter. My older sister bought them her first year of college with AR turntable, Marantz receiver and KOSS headphones. I have been a high-fi nut ever since. I saw your website with schematics before joining this forum. I have pictures of the crossovers which I will upload. They are the same as in your pictures but for the off-white tweeter inductor.

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Thanks a bunch Pete,

I have a pair of the Advent V2 with the date May 1, 1974 stamped onto tweeter. My older sister bought them her first year of college with AR turntable, Marantz receiver and KOSS headphones. I have been a high-fi nut ever since. I saw your website with schematics before joining this forum. I have pictures of the crossovers which I will upload. They are the same as in your pictures but for the off-white tweeter inductor.

Your welcome and thanks for commenting!

I'd like to see those pictures.

If they were not off-white what color were they?

Or were they unpainted? Always good to hear about another sample.

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Guest shutupuface
Thanks a bunch Pete,

I have a pair of the Advent V2 with the date May 1, 1974 stamped onto tweeter. My older sister bought them her first year of college with AR turntable, Marantz receiver and KOSS headphones. I have been a high-fi nut ever since. I saw your website with schematics before joining this forum. I have pictures of the crossovers which I will upload. They are the same as in your pictures but for the off-white tweeter inductor.

Hi! I'd like to see the pics of the crossovers !! Thanks, again!

Best regards,

Rob :)

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Guest Synthsayer

The photos came out really blurry. Sorry. I will be working on them again soon, (next week) and take better pics. I can't read the values, but Cap values are the same as given in previous post. The only difference is the small round inductor. I didn't want you to think I was not replying to posting.

I will attempt to create links to photobucket images. Not too good with HTML yet. Please be patient if I mess it up. :blink:

I will also include EV Aristocrat Corner Horn and EV HR 9040s w DH1012 drivers for the heck of it.

PEACE

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