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You can now salvage un-salvageable OLA's


Carlspeak
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This thread is intended to help those who have either rescued curbside castaways, or bought a pair for a few cents on the dollar that have blown drivers. You can turn them into great sounding Advents with the purchase of new woofers, tweeters and a simple crossover for a little over $300.

All this has come about as the result of a recently completed project with a customer who came to me with an objective of creating a whole new OLA with all new parts and even new cabinets he wanted to build for himself but, at the same time, retain the original Advent sound. The new cabinet is not essential to this discussion because he duplicated the basic size, internal volume and baffle board locations of the woofer and tweeter. I was charged with identifying the drivers and crossover design. He built his own cabinets. I had two OLA's in my possession to use as prototypes to mod at my whim. They were of a vintage that had metal frame woofers and foam blocks for stuffing. Those same speakers are now FS in the classified section of this forum. After he built the cabinets, he sent one to me for final assembly and testing to verify the results I had gotten with the modded OLA prototype.

At the far left below is the end result of the project. Next to that is a pic of what is possible for a salvage job. It shows the new woofer and tweeter with an easy to fabricate masonite adapter plate installed in an OLA cabinet. I call it the Ni-OLA or New, improved OLA. It's improved because the new crossover and tweeter have resulted in a flatter frequency response above 1 kHz and increased HF extension flat almost to 20 kHz; something the original 'fried egg' tweeter doesn't come close to. Also, distortion is lower and efficiency is a bit higher at over 92 dB w/2.83 V @ 1 M.Third from left is an on axis FR test of the Ni-OLA. To it's right, FR tests of the OLA with original fried egg tweeter and crossover. Follow the upper blue line which is the on axis response. Note the dip at 2 kHz and spiking and roll off at 15 kHz.

Note to the techies, most of the FR plots I've posted were done with 1/12th octave smoothing.

Project details continued in next post.

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If that metal frame woofer in the pics in the OP looks familiar it's because it a commercially available drop in woofer sold by Madisound, Simply Speakers, vintage-AR and maybe a few others. I tried it first because it represented the simplest replacement as far as fit and finish goes. The new drop in has it's advantages and dis-advantages. Above 200 hz, the new woofer is identical to today's original, vintage metal frame woofers. Follow the upper blue lines in the two plots below. These tests were run with each woofer in the same OLA box with original foam blocks stuffing. One plot can pretty much be overlaid on top of the other. So, the upper bass and lower midrange music reproduction will be essentially identical. Below 200 hz, the new woofer doesn't have the bass extension of originals. It seems the spider is somewhat stiffer. However, some of that loss in bass extension can be made up by modding the cabinet stuffing to deliberately raise the "Q" of the speaker well above 1.

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On to the tweeter. I identified an excellent high powered, low distortion tweeter from Dayton. The RS28F-4 model. Crossed at about 1 kHz, 2nd order the tweeter has better 3rd harmonic distortion than the original. The tweeter has a 20 uF series Erse MET cap and a parallel 0.5 mH 20 ga air coil. The dip in the 1-2 kHz range of the OLA was solved by running the new woofer full range w/o a series coil. Tests were run to see if some BSC could be added with a 1.5 mh coil, but it wasn't significant enough to warrant sacrificing the solution to the 1-2 kHz response dip. After some final voicing tests with the customer's participation it was decided to add a 3 ohm resistor in series with the tweeter. The new crossover does not have a switch like the original. I felt it wasn't necessary. Below are plots of near field response tests done on the Dayton tweeter, 1st with a very high uF cap just to see it's general reaponse, then with the final 20 uF cap chosen and 3rd with the 0.5 mH shunt coil added.

The masonite adapter plate is quite simple. Copy the size of the OLA tweeter aluminum plates size and hole pattern and put a 3 inch diameter hole in the middle with notches at the 3 and 9 o'clock position to clear the speaker wire tabs on the Dayton tweeter.

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Lastly, stuffing changes for bass extension. Near field woofer FR tests were done with 1.5 lbs OCFg and minimalist stuffing (see plots below). Note the increase in the height of the response hump in the 80-120 hz range with minimalist stuffing (right plot). With 1.5 lbs OCFG, but Q was about 0.9. With minimalist stuffing (back wall only), Q was raised to 1.2.

After working with the customer on stuffing tweaking, he advised he was most satisfied with the sound with the installation of a 20X20X2 inch thick open cell foam block folded at the sides and placed against the back of the cabinet. This foam can be obtained from Joanne's Fabrics and craft store. Also 2 inch thick blocks of foam were added at the top and bottom of the cabinet.

One can work with either minimalist FG or foam stuffing wich is needed to mitigate internal cabinet reflections and target for a "Q" of >>1.0

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Nice work Carl, I've been thinking of doing something very similar with that Dayton tweeter, given

it's LF capability and price. Though I'd expect to use a different crossover.

Are your measurements with the actual OLA box or the customers?

Were they grill on or off?

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Nice work Carl, I've been thinking of doing something very similar with that Dayton tweeter, given

it's LF capability and price. Though I'd expect to use a different crossover.

Are your measurements with the actual OLA box or the customers?

Were they grill on or off?

I have both. Also with and w/out the grille. Most or all of what I have shown is w/out the grille.

BTW, the customer revised his grille a bit from original by putting the 6 velcro blocks on the grille instead of the baffle board. So, just the velcro strips are attached to the BB so it looks much cleaner with the grille off. I can provide the other tests privately if you request them. However, with or w/out the grille didn't make a significant difference to the FR.

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Nice work Carl.

I suppose we're getting into the "mods" area now but have you looked at the 12" Mavin EM-TL3006Y-8 Woofer? They claim it's a drop-in replacement for the Large Advents. All the T/S parameters are shown on their website but it's mostly Greek to me ;)

I know the OLA Advent woofer was 10" in a 12" frame but wonder if this (or any) 12" would give the bass extension you say the Madisound/SS replacement lacked.

The sales pitch on their site says

"Proven and tested, it sounds just as good, if not better than the original Advent drivers. Over all still a very good sounding speaker, much like we remember, with a bit more low end punch".

-Kent

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Nice work Carl.

I suppose we're getting into the "mods" area now but have you looked at the 12" Mavin EM-TL3006Y-8 Woofer? They claim it's a drop-in replacement for the Large Advents. All the T/S parameters are shown on their website but it's mostly Greek to me ;)

I know the OLA Advent woofer was 10" in a 12" frame but wonder if this (or any) 12" would give the bass extension you say the Madisound/SS replacement lacked.

The sales pitch on their site says

"Proven and tested, it sounds just as good, if not better than the original Advent drivers. Over all still a very good sounding speaker, much like we remember, with a bit more low end punch".

-Kent

Thanks Kent. Looking at the specs, some of which don't make sense, I feel it will not work as well as the MS/SS one. For starters, the Fo (should be Fs) is higher than the MS woofer and Qts puts the woofer in a boom box category.

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since you're replacing drivers, have you looked at the eclipse woofers offered by meniscus? they're made by MISCO in Minneapolis instead of asia, and are pretty reasonably priced....

here's the 10"

http://meniscusaudio.com/eclipse-w1038r-p-567.htmlis the 10"...here's full specs on MISCO's website http://www.miscospeakers.com/speakers/OC10W-8D

and the 12"

http://meniscusaudio.com/eclipse-w1238r-p-568.htmland full specs on MISCO's website http://www.miscospeakers.com/speakers/OC12W-8D

IIRC when I was playing with the t-s specs, either one sim'ed to a -3db cutoff at about 40hz, with -10 in the mid 20's in about 1.8 cubic foot sealed.....

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since you're replacing drivers, have you looked at the eclipse woofers offered by meniscus? they're made by MISCO in Minneapolis instead of asia, and are pretty reasonably priced....

here's the 10"

http://meniscusaudio.com/eclipse-w1038r-p-567.htmlis the 10"...here's full specs on MISCO's website http://www.miscospeakers.com/speakers/OC10W-8D

and the 12"

http://meniscusaudio.com/eclipse-w1238r-p-568.htmland full specs on MISCO's website http://www.miscospeakers.com/speakers/OC12W-8D

IIRC when I was playing with the t-s specs, either one sim'ed to a -3db cutoff at about 40hz, with -10 in the mid 20's in about 1.8 cubic foot sealed.....

Sorry, didn't look at those. Obviously, there are so many to choose from and I don't have the resources to evaluate a large number. For this project I favored not sacrificing midrange = to that of the original metal frame over bass extension.,

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Nice job, Carl.

Is the volume on the OLA cab similar to the AR-5/AR-14 cab?

Roger

I'm familiar with the OLA volume having worked on this project recently. It's 1.6 Cu. Ft. Not as familiar with those AR cabs. Perhaps Roy C. could chime in with some volume info.

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I'm familiar with the OLA volume having worked on this project recently. It's 1.6 Cu. Ft. Not as familiar with those AR cabs. Perhaps Roy C. could chime in with some volume info.

Using external measurements I get a volume of 1.56 cu. ft. subtracting 0.75 inch for sides for the AR-5 cabinet.

Oops, maybe not, just found a reference which says 1.35 cu ft. for the AR-5.

Efficiency of popular AR and Advent Speakers in the 1970's It could be useful in the case of using brand A woofer in brand B cabinet:)

Speaker Efficiency: An Initial Review

Article By Peter W. Mitchell

From BAS August 1973

http://www.enjoythemusic.com/magazine/bas/0808/

The efficiency here is listed as db/watt not the more useful db/2.83v, however.

Nice reference for info I'm sure not a lot of people are up on. It shows one reason why JBL Century 100's were so popular.

Roger

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The Q and A in posts #11 and 12 piqued my curiosity about where the OLA cabinet volume would fall compared to the AR line-up, and I was just looking into this when Roger was writing post 14.

It feels a little weird to post this summary in the Advent forum, but WTH, that's where this question arose. All of these figures have been plucked from AR literature, and it is interesting to confirm that the OLA has nearly the volume of the largest AR's of this era.

Classic series

1.70 cu ft (48.2 litres): AR-3a, AR-LST

1.60 cu ft (45.3 litres): OLA

1.35 cu ft (38.2 litres): AR-5, all AR-2 series, AR-LST/2

0.65 cu ft (18.5 litres): AR-6, all AR-4 series

0.35 cu ft (9.77 litres): AR-7

ADD series

1.48 cu ft (41.9 litres): AR-10pi, AR-11, AR-12, AR-14

0.64 cu ft (18.0 litres): AR-15, AR-17

0.35 cu ft (9.77 litres): AR-18

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The Q and A in posts #11 and 12 piqued my curiosity about where the OLA cabinet volume would fall compared to the AR line-up, and I was just looking into this when Roger was writing post 14.

It feels a little weird to post this summary in the Advent forum, but WTH, that's where this question arose. All of these figures have been plucked from AR literature, and it is interesting to confirm that the OLA has nearly the volume of the largest AR's of this era.

Classic series

1.70 cu ft (48.2 litres): AR-3a, AR-LST

1.60 cu ft (45.3 litres): OLA

1.35 cu ft (38.2 litres): AR-5, all AR-2 series, AR-LST/2

0.65 cu ft (18.5 litres): AR-6, all AR-4 series

0.35 cu ft (9.77 litres): AR-7

ADD series

1.48 cu ft (41.9 litres): AR-10pi, AR-11, AR-12, AR-14

0.64 cu ft (18.0 litres): AR-15, AR-17

0.35 cu ft (9.77 litres): AR-18

I'm sure others will be interested in this in the future as more cabs and less drivers are available. Maybe a repost in the AR section for reference value is in order.

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  • 1 month later...

Hello,

I was searching for a replacement tweeter for my large Advents, and found this. I have a set of the new Large Advents, and the later 5012/w's. I'd like to have 4 speakers all the same (stackable), and replace the tweeters (especially the fried egg ones) with something better.

I've got the woofers refoamed, and the cabinets of the 5012's braced. I plan on using fiberglass packing. just need a little more information about the crossovers.

Would the crossover you listed Carl work well with the Dayton RS28F-4 tweeters, and the original woofers?

If so, could you post a parts list including brands, and a good place to purchase them?

Maybe, also a wiring diagram, so an electrical noob like me won't mess it up? I can solder though.

Thanks for posting all this info, I'm pretty eager to hear what they're going to sound like.

Dean

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Hello,

I was searching for a replacement tweeter for my large Advents, and found this. I have a set of the new Large Advents, and the later 5012/w's. I'd like to have 4 speakers all the same (stackable), and replace the tweeters (especially the fried egg ones) with something better.

I've got the woofers refoamed, and the cabinets of the 5012's braced. I plan on using fiberglass packing. just need a little more information about the crossovers.

Would the crossover you listed Carl work well with the Dayton RS28F-4 tweeters, and the original woofers?

If so, could you post a parts list including brands, and a good place to purchase them?

Maybe, also a wiring diagram, so an electrical noob like me won't mess it up? I can solder though.

Thanks for posting all this info, I'm pretty eager to hear what they're going to sound like.

Dean

The crossover for the tweeter is shown and discussed in post #3. There's a 20 uF cap in series with the tweeter pos post and a 0.5 mH 20 ga. coil attached right after the cap and the other end of the coil attached to the negative wire. After the coil, attach a 3 ohm resistor.

All of those parts are available at Parts Express.

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Very interesting, and well done. Undoubtedly many people will find this useful for broken Advents.

Out of curiosity, what causes the 1-2K dip in the OLA's frequency response?

Based on my tested of the one 'prototype' original on hand it was the inductor coil on the woofer. Take it away and away goes the dip.

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Hello All,

I am the customer that Carl has referred to in the previous posts. The original idea was to duplicate the sound of the OLA using modern components and a higher quality cabinet. Carl picked out the drivers (after a lot of research) and built the final XO. I built the cabinets. The cabinets are made of 5/4 hard maple with the exact same volume as an OLA. They also have a front-to-back brace (centered).

As can be ascertained from the previous posts, there was a substantial amount of experimentation with stuffing and electrical components to get "the sound". I was constantly comparing the new speaker to OLA's that I own.

I have 4 OLA's that I drive with a 1976 JVC 4VR-5456X receiver. I removed the 2 front speakers and replaced them with Carl's Maple Monsters :)

I, my wife, and some music appreciating friends, now have over a week listening to them; as stand alones in 2ch stereo; and with the OLA's as rears in 4ch (that's Matrix 1 on the receiver). I also reversed the speakers; OLA's in front and new / maple in the rear. It is virtually impossible to tell the difference between the old and the new. If anything the new / maple speakers are probably a "half-a-notch" better than the OLA in a 2ch / 2 speaker / stereo configuration.

All that being said, I believe that Carl has come up with a real and viable alternative for reproducing the famous Large Advent "colorless" sound; without dealing with re-foamed / coned woofers or burnt out fried egg tweeters. An OLA cabinet could be used or a new cabinet that remains faithful to the original OLA qualities and characteristics could be used.

Thanks for hearing me out. An my sincere thanks to Carl for the effort.

Gotta go listen to some Blues. Jim Nettle

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  • 4 years later...

Carl,  I'm brand new to this site and have managed to pick up two pair of Large Advents, one is the NLA (paid $10 for the pair at a local thrift store and refoamed them myself) and the other is a later version without the switch. hey are marked 'ADVENT/1' on the terminal plate. (refoamed them as well).   I wondered if you could post a circuit diagram of your new crossover including connections to the woofer and tweeter.  It would really help my understanding.

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Welcome to CSP RD

Nice finds with those Advents.

Sadly, our friend and forum moderator Carl Richards passed away a couple of years ago. PeteB is probably the best person to answer your questions. Here is his web page on Advents: http://baselaudiolab.com/ADVENT_LA_XO.html I think Pete recommended using the Rev. 2 crossover, and the schematic diagram is on that page. I would not use Carl's crossover because it was designed for that replacement tweeter (which is no longer available).

You may also find this interesting: https://audiokarma.org/forums/index.php?threads/identifying-your-advent-loudspeakers.126376/

Kent

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