OLA crossover help please

[drmoron]

This is my first post to this group, but I have been reading a LOT for a few years and thank you all for the great source of information!

I currently own (and love) 4 OLA's stacked and a pair of smaller Advents in another room. The smaller ones I replaced the entire crossover when I had them apart to veneneer the cabs... unstained walnut... much nicer! Crossovers pretty straight forward. The OLA woofers have been re-foamed and one needed the coil re-worked (Thanks again Carl!) Mine are the 2-16 cap and 3ohm resistor variety with the large inductor attached to the back of the cab and the red and white "button" inductors. I am NOT a full techie but understand the aging process of caps. So as a minimum I would "assume" I should replace all the caps and resistors. I can handle soldering parts , BUT do not own, nor care to own, a multimeter for testing.

Question 1: should I replace the inductors as well, as I am already in the cabs soldering?

Question #2: After reading and reading I "think" that I have understood that there are the 3 crossover versions YET the woofers and tweeters did NOT change. IF this is true then would it not be possible to use any of the 3 crossover designs regardless of what the original was? (assuming also replacement of ALL components including inductors). IF SO then which crossover version works best?

Please... while appreciate the guru's and the ultra high tech talk, can someone splain dis to me so a "average" guy can grok it without raising doubts in my average brain?

Thanks!

David

[Pete B]

The Red and White button inductors did not handle much power,

so it would be prudent to measure the DC resistance of them

before finishing the job. The Red one is about 2.2 ohms.

I believe that the OLA is the best sounding of them all, and

I have A/B compared OLA, NLA, and the 5002.

The drivers were all new in the NLA, the woofers were

functionally identical, the tweeters were not. The Jensen

5002 drivers were also different.

What I called Rev0, Rev1 and Rev2 were all for the OLA with

what we think were essentially the same drivers. If you tend

to listen with them set to Extended and find them to be a bit

too forward with Rev1, then Rev2 might be better for you.

Rev2 will also handle more power since the tweeter inductor is

more robust.

I see below that JKent provided a link to the site documenting

the various versions.

Another question is how much do you want to spend on these, are

they your main speakers?

[JKent]

as a minimum I would "assume" I should replace all the caps and resistors.

Welcome David!

Pete neglected to provide a link to his excellent Advent site, so here it is:

http://baselaudiolab.com/ADVENT_LA_XO.html

Just one comment: Wire wound resistors do not normally need replacement. OTOH, the resistors in the OLA are 5 watt, which I've found to be a problem in some KLH speakers. May as well replace them with 10 watt when you replace the caps

Kent

[drmoron]

Thanks Pete and Kent!

The stacked OLA's are my main listening set. As far as cost is concerned, I don't mind investing in these as they certainly worth it. If I had to assess my OLA's current sound Id say awesome in the low end, perhaps lacking a bit of clarity and presence in the middle and the highs. From what I have read this is likely symtomatic of old caps, yes? I find that using the "extended" on the tweeters makes it a bit harsh and less clear to my ears.

Costs are not a real issue as long as it has a clear audible advantage not just better readings on a meter. My room is far less than perfect and I won"t be moving soon for the sake of my speakers. I usually get parts from PE and notice that they list Solen caps at 16uF but the daytons at 15uF (no 16's) so left un-advised I'd go with the Solen's only because the specs match. I have no brand loyalty and have to gleen the best direction from the kindness of strangers, such as yourself, for what to buy. For resistors the Mills 3ohm/ 12W seem to fit the bill and as I gather from Kent's comment the higher wattage rating is a good thing with no sonic impact.

If I replace the inductors this seems to be a far more daunting task, as I dont see anything that matches the specs.

Thanks for your help!

David

[Pete B]

How many watts are you driving them with?

I'd say that if you run 100W/ch and you really turn it up

from time to time that you might hear a difference going

to air coir inductors.

If you run less than 50W/ch then they probably would not

make a difference.

Erse 3% polys are a good choice, or Dayton 1 or 5%.

Those resistors are fine.

I advised JKent on here in another thread on how I would

upgrade the inductors if they were my main system. I had

the wrong impression that he was serious about them. Here

is the link:

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4919

[JKent]

Inductors are tough to replace (to get the correct values) and since most are just coils of wire, there's no real need. Pete can better advise you there if you have the button caps he mentioned. Also, Pete has said air-coil inductors are better, so you "could" replace all the inductors. Problem is matching them, both in terms of the inductance (measured in henries) and the DCR.

I have used Mills resistors and like them very much. They are compact and easy to work with. Plain Dayton sand-cast wire wound resistors are fine too.

The difference between 15uF and 16uF is insignificant. 15uF will work fine. Or, if that bothers you, you can combine a 1uF and a 15uF in parallel to make 16. Or if you want to get really fancy, you could try "cascading":

http://www.northcree.../Bypassing.html

Another choice would be Carli mylar caps from Madisound--that is what I am using in my as-yet-unfinished OLAs (which, btw, I AM "serious" about--just a bit slow, and I prefer to keep the original design). A cheap way to experiment with cascading would be to use a Carli 15uF 150v + a GE 0.68uF 600v + a GE 0.33uF 850v, all from Madisound. Price for the 3 caps: $4.80. Note that most members whose opinions I respect (including Pete) think bypassing or cascading is rubbish.

Madisound has Mundorf 3.3 ohm 10w resistors, Eagle 2.7 ohm 10w, or 3 ohm 15 w generic resistors. All close enough.

Finally, here's something that probably WILL make an audible difference: Add bracing. Carl discusses this in another thread (see post #12):

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2895&st=0&p=67529&hl=improvement&fromsearch=1entry67529

Kent

[Pete B]

Inductors are not really tough to replace it is just that they are

less often changed and people less skilled in the art therefore

think that it is more difficult. However, distortion in iron core

inductors is all over the map depending on the type of core material

used whereas most capacitors have very low distortion levels so it

really makes very little sense that many people believe that there

are huge differences in caps.

I suggested inductor replacements that will work just fine in your

thread. Air core inductors unlike iron core do not have any

saturation distortion. I would only change the inductors in Advents

used as a main system driven with a lot of power. I'd also do

them before using any expensive boutique caps.

The Carli mylar caps that Kent references are a notch below polypropylene

types and have a 10% tolerance. You have to judge if you want to cut

corners there and I prefer 5% tolerance or less for speakers used in

a primary application. I used Dayton 1% caps in my Advents just

because my intention is to have a reference pair built as close to

spec as possible and I did not want to measure and hand select the

caps. The Erse 3% (PULSEX) polypropylene caps are another fine choice.

If you can't find a 16uF in the type of cap you choose, just use a

combination that gets you 16 uF. 8 + 8, or 12 + 4, 10 + 6, etc. and

put them in parallel.

[JKent]

I suggested inductor replacements that will work just fine in your thread. Air core inductors unlike iron core do not have any saturation distortion. I would only change the inductors in Advents used as a main system driven with a lot of power. I'd also do them before using any expensive boutique caps.

I may replace those iron-core inductors as you suggested, Pete. My experience with certain AR speakers (think it was when I was working on the 3a's) was that it was difficult to find replacement air core inductors that were both the correct value in uH AND the correct DCR. I seem to remember having a tough time with that. But the more I get into the electronics, the less hesitant I've become. The OLA project may very well evolve into the full upgrade you recommended. You recommended a specific inductor for the woofer (in the Rev 2 xo): http://www.parts-exp...tnumber=266-360 but will have to search out the others. So I need 1.6mH .28 ohm, .065mH .30 ohm and .45mH .25 ohm. You wrote:

The button is the smallest one, the small bar is the .45 mH, and the large obviously is the 1.6 mH. The .44 mH 18 ga would be fine

I agree regarding the Erse caps. Just used them in my AR91 restoration.

Now the big decision is: Do I refoam the Masonite-ring woofers myself or send them to Bill LeGall? Given my recent experience with him, I'm leaning toward having him do them.

Kent

[drmoron]

I am in about the same place regarding the inductors as you Kent. The 1.6 seems to be the easiest to find FYI if your want to spend more than double, Erse has 1.60mH 12ga FoilQ - .265Ω 1000W - Copper Foil Air Core Coil. Which brings me to my next question. What is more crucial to match exactly, the mH or the ohm rating, and how far off can the part be to the specs? Most coils I see have half the ohm rating for the same mH value; for instance for the Rev1 L2 inductor calling for .2mH at .55 Ohms I can get a .2mH at .29 Ohms; or to get he Ohms right I'd have to go to a .6 mH at .53 Ohms.

One thing that makes no sense to my brain is the ohm rating for the L2 coil in the specs listed for the first revision crosover at http://baselaudiolab.com/ADVENT_LA_XO.html it list this as .8mH at 2.3 Ohms. Even the second revision has L2 rated at .45mH .25 Ohms/ IS this a typo for The first revision? how can you have .8mH with such a high ohm rating?

I guess I may just replace the caps (likely the Dayton 1% 15uF and 1uF's as per Pete's suggestion) Mills resistors and the large inductor along with increasing the fiberglass packing as I have realized after my reading's here, I have about half as much as I should. I looked over Carls bracing and I am considering it. My hesitancy is risking messing up my cabs.

You guys are great... thanks for your help!

David

[JKent]

Hi David. You are having the same problem I did. Maybe someone who understands these things will help out here.

Regarding the caps, I doubt it is worth the expense to get the Dayton 1% over the Dayton 5%. Cap tolerances are pretty broad (I think -20%, +70% is considered within spec) and most of the 5% Daytons AND the Carlis are pretty much spot on.

Doubt the bracing will mess up the cabs. You need to get the length perfectly accurate but otherwise the dimensions or even species are not critical. A bit of glue and screws and you're done. The screw heads won't show because they are behind the grille and on the back of the cab.

Disclaimer: I have not done the bracing yet (but plan to)

Kent

[drmoron]

Thanks Kent

You are right the 5% daytons would save some $, about $42 for my 8 speakers. Personally, I am going for the better caps as fortunately for me the $ isnt an issue. I'd rather get the small inductors replaced and switch my crossover rev from my current 16/16/3 to the 16/8/3. Heck I dont know if these inductors make any difference as I am like a weekend mechanic.... tell me what filter and brand oil to get and I'll go change the oil in the car... just dont ask me how the engine works or why Oil brand A is better than brand B!

That is exactly my hesitation re the cab bracing. My carpentry skill are not good and I dont like my odds at cutting 16 pieces of braces to exact lenghts! But I have veneered my original EPI 90's and my Small Advents. If you have the vinyl cabs... do it! http://www.veneersupplies.com/ Iron on paper backed veneer, heat lock glue and an edge band trimmer.... a little sanding, staining if you wish, and some poly finish and you get a beautiful looking speaker. If you have dents or damaged corners, bondo for the larger areas or wood fill for the small ones; overfill, sand it smooth then the veneer and you have speakers that look like the day they rolled off the factory floor. If you have things apart to do the crossovers that is the time to do it.

David

[drmoron]

Kent

After a lot of research, from what I am reading the values on the small inductors is not crucial. What I am seeing is get it as close as available and dont worry about it. This is IF you even have to or even want to replace them. I am switching my 16uF/16uF caps to the later version 16uF/8uF, as this seems to give a smoother high end in extended position, which is why I am replacing all inductors. FYI you can get Solen caps rated at 3% variance for just a little more $ than the Dayton 5% ones. From photos I believe that these Solens are the ones offered in preassembled replacement crossovers for sale. Also, watch the shipping cost from where you order, it may negate any "savings".

This is my shopping list for my 4 OLA's all from PE:

4-1.5mH 14 AWG Perfect Layer Inductor Part Number: 266-360

4-Jantzen 0.05mH 18 AWG Air Core Inductor Part Number: 255-200

4-Jantzen 0.44mH 18 AWG Air Core Inductor Part Number: 255-226

4-Dayton PMPC-8.2 8.2uF 250V Precision Audio Capacitor Part Number: 027-242

4-Dayton PMPC-1.0 1.0uF 250V Precision Audio Capacitor Part Number: 027-210

4-Dayton PMPC-15 15uF 250V Precision Audio Capacitor Part Number: 027-248

4-Mills 3 Ohm 12W Non-Inductive Resistor Part Number: 005-3

Total cost:$235.52 Shipping:$0

Now... to brace or not to brace.

David

[Pete B]

I think I have said it several times, there is no point in changing

the inductor if you do not drive the system hard. If you don't mind

blowing the money and want the best because they are your main

speakers then go ahead it is a far better investment than boutique caps.

The DC resistance of the woofer inductor is in series with the amp

and woofers. It is the same as resistance differences in wire. A

tenth of an ohm difference here or there doesn't matter. If you use

thin wire and a tube amp with low damping factor then there is really

no point in worrying about going up a few tenths in resistance. It is

also in series with the DC resistance of the woofer or about 5 ohms so

a tenth in comparison is small.

The early Advent did have a 2.2 ohm inductor which limits the max

low frequency attenuation that it provides. It was probably done

for economy reasons and the factory tweeter replacement instructions

state to check this inductor since it too often failed when the

speaker was over driven. This would never happen with reasonably

sized inductors as in the 16/8/3 version.

I believe that Zalytron has some of the best prices on inductors,

but check shipping charges of course:

http://www.zalytron.com/erse.htm

Those choices look fine David, you might want to make the resistors

3.5 or 3.3 ohms if they are available to make up for the lower

resistance in the film caps, especially if you already find the

LA to be a bit forward or bright. It is a lot of money so you might

want to check Zalytron also.

[drmoron]

Pete,

Thank you. I will up the resistor as you suggest. I do sometimes run them hard and they are my main system, so the cost for the smaller inductors is not that much extra. This way I'll be confident that these will last me the rest of my life and hopefully be passed on to a family member in my will!

Now I can get to what I "know" soldering. LOL

Again, thank you for all of your help, I truly appreciate it!

David

[Pete B]

You're welcome David.

Kent, I'm not trying to pressure you to use the air core inductors,

especially since these do not seem to be your main speakers. I am

surprised that you are not moving faster on them given your strong

interest in KLH and Henry Kloss' designs ... and the excellent reports

by so many for the LAs.

Refoam them yourself, and leave the dust caps in place, many have

stated that they are one of the easiest to refoam.

[JKent]

Thanks Pete.

Still undecided on the inductors but moving in that direction.

My slowness comes from 2 places: I'm a little hesitant about refoaming them, gluing the foam from behind so it is like the original. If you say it's easy, I'll give it a shot.

The other thing is there are just so MANY projects here. I just finished the AR91s and before those the AR3a's. Also refoamed the sub from my wife's car and "should" get around to reinstalling it. As you know I undertook recapping my MAC and Advent receivers, and I'm constantly restoring KLH Eight radios and Thirteen Stereo adaptors, and building my little iPod gadget for the Eights. AND it's summer so there are lots of activities.

People sometimes ask: "You're retired? What do you DO with all that time?"

HA!

Kent

[Doug G.]

Kent, by "gluing the foam from behind" do you mean behind the masonite ring?

If so, it's a piece of cake. Or piece of foam, as the case may be.

Just glue it to the front of the cone first. And then, after the glue has set a bit, push down on the cone so you can get to the outer flange of the foam. Put a bead of glue all around and let it back up against the back of the masonite.

Make sure it doesn't rub no matter where you push on the cone, let it set/dry and it's ready to go.

Doug

[JKent]

Well, thank you all for the encouragement. I did them today. Will test tomorrow.

Directions from M_Sound were helpful:

When time comes to attach the foam to the back side of the Masonite, start with the woofer sitting on its back. Have your shims tight enough to hold the foam up while you apply glue to the foam surfaces, then just flip the woofer over & working thru the holes in the frame, apply glue to the Masonite. Then simply lower the cone & foam onto the Masonite. Only lower the cone assembly enough to let the foam barely touch the Masonite. It will find it's own natural center as the shims help hold it centered. Once you are sure the foam is centered, let it down further & press it down evenly. Leave the woofer sitting on it's face like that till the glue has time to set.

I basically followed that, but found it easier to just smear glue on the back of the Masonite with my finger, from the front. It's water-soluble.

Looking forward to trying them out. I had forgotten how BIG the cabinets were! Thought they were similar to the 2ax, but they're even bigger than the 3a's!

Kent

[Carlspeak]

Here is an OLA crossover upgrade I've completed for a customer who wanted new, very high quality components.

In the picture below you can see all of the coils and caps have been replaced. The 3 ohm resistor is new as well. Cardas solid copper binding posts have replaced the old SS screws. The 16 uF cap is an Auricap. The large one (behind the front-to-back brace dowel) is an 8 uF Hovland. The large woofer coil is an Erse 1.8 mH 14 ga perfect lay. It's a bit higher in value that what Pete B. has measured but was the closest I could find in both mH and DCR to oroginal. I ran WT2 scans on the original iron core woofer coil and the new one. At about 1100 hz (crossover area) the inductive reactance was 11 ohms in the original and 12.9 in the new one. The original meas. 1.56 mH and .23 ohms DCR. The new one meas. 1.82 mH and 0.26 ohms.

The small coil is an Erse 0.05 mH 16 ga. FoilQ. The other is a 0.45 mH Erse 16 ga. FoilQ.

I've also included an acoustic frequency response measurements taken on axis @ about 1M for the blue line (switch in increase pos.) and near field on the woofer for the red line. Quite a smooth response from 80 out to 13 kHz where the fried egg tweeter seems to poop out. I'm lookiing forward to giving them a good listen before I ship them back to New Mexico.

[JKent]

I suggested inductor replacements that will work just fine in your thread. Air core inductors unlike iron core do not have any saturation distortion.

Maybe I missed it Pete, but I can't find specific recommendations on the 2 small inductors. I did some searching but still have a question:

According to your web page, L2 is .065 mH and about .30 DCR. The .05uH 18 ga coil from PE is .09 DCR. Looks to me like a big difference. I checked the Erseaudio .05 18ga and that's about the same (.086 DCR). Are these appropriate replacements?

Good lead on Zalytron. Looks like they are about 1/2 the PE prices, but they do not have the .05 (.065) size. But if that Jantzen .05 18 ga will work, I happen to have a couple on hand. So.... are these good choices from Zalytron:

1.50mH .278 DCR 14 ga Perfect Lay $13,53

.47mH .482 DCR 20 Ga $1.85

Or, buying from Erseaudio, how do these look?

1.5mH 14 ga .278 DCR XQ - Perfect Lay 22.30

0.07mH 18ga .11 DCR EQ - Perfect Lay $2.40 (or) .05mH 18ga .086 DCREQ - Perfect Lay $2.31

.45mH 18ga .298 DCR EQ - Perfect Lay $4.65

Kent

[Carlspeak]

Kent, certainly shop for the best price but be aware getting pretty close to original component mH and DCR will be good enough. If you can measure mH, you may want to consider getting coils slightly higher in mH value than target and taking off a few windings to get right on target if that's your goal.

However, just look at the acoustic response I got with the components I used.

[JKent]

Kent, certainly shop for the best price but be aware getting pretty close to original component mH and DCR will be good enough. If you can measure mH, you may want to consider getting coils slightly higher in mH value than target and taking off a few windings to get right on target if that's your goal.

However, just look at the acoustic response I got with the components I used.

Thanks Carl. I was admiring that crossover. First class!

I'm not going all-out as you did for that customer, but I have 2 questions:

Did you use the original switches (and if not, what did you use?). I had planned on leaving the originals.

What about the question I posed to Pete? According to his chart, L2 is .065mH and .3 DCR. I can find nothing that even approaches that resistance. The Jantzen and Erse (both wire and foil) are less than .1

Is that a problem or is it good enough?

Kent

[Carlspeak]

Thanks Carl. I was admiring that crossover. First class!

I'm not going all-out as you did for that customer, but I have 2 questions:

Did you use the original switches (and if not, what did you use?). I had planned on leaving the originals.

What about the question I posed to Pete? According to his chart, L2 is .065mH and .3 DCR. I can find nothing that even approaches that resistance. The Jantzen and Erse (both wire and foil) are less than .1

Is that a problem or is it good enough?

Kent

I used the original switches. They were tested with the new components installed. Three acoustic response tests were done with the switch in each of its 3 positions to confirm functionality before I stuffed the cabs with about 2 lbs of OCFG. Cabinet Fc was slightly less than 38 hz. NICE!

To answer your last question, I again refer you to the acoustic response test I ran. The wire size on the small, red button coil must be very small to yield that high a DCR. Perhaps Pete could run a Spice simulation with the <0.1 DCR to see what theoretical impact that might have.

IMO, this isn't rocket science and close is good enough when the music is playing. Pete may have a different opinion.

[Pete B]

Maybe I missed it Pete, but I can't find specific recommendations on the 2 small inductors. I did some searching but still have a question:

According to your web page, L2 is .065 mH and about .30 DCR. The .05uH 18 ga coil from PE is .09 DCR. Looks to me like a big difference. I checked the Erseaudio .05 18ga and that's about the same (.086 DCR). Are these appropriate replacements?

Good lead on Zalytron. Looks like they are about 1/2 the PE prices, but they do not have the .05 (.065) size. But if that Jantzen .05 18 ga will work, I happen to have a couple on hand. So.... are these good choices from Zalytron:

1.50mH .278 DCR 14 ga Perfect Lay $13,53

.47mH .482 DCR 20 Ga $1.85

Or, buying from Erseaudio, how do these look?

1.5mH 14 ga .278 DCR XQ - Perfect Lay 22.30

0.07mH 18ga .11 DCR EQ - Perfect Lay $2.40 (or) .05mH 18ga .086 DCREQ - Perfect Lay $2.31

.45mH 18ga .298 DCR EQ - Perfect Lay $4.65

Kent

The lower or about equal DC resistances are fine.

The .47 mH .482 DCR 20 Ga. is a bit high on DC resistance

which just makes it closer to the 16/16/3 crossover, but

why not go to an 18 ga. to keep it as close as possible?

If they don't have one, then it should be fine.

The lower DCR in the decrease inductor doesn't matter since

it is in series with the 3 ohm resistor and the DCR of the

tweeter very small difference on a percentage basis.

[JKent]

The lower or about equal DC resistances are fine.

The .47 mH .482 DCR 20 Ga. is a bit high on DC resistance which just makes it closer to the 16/16/3 crossover, but why not go to an 18 ga. to keep it as close as possible?

If they don't have one, then it should be fine. The lower DCR in the decrease inductor doesn't matter since it is in series with the 3 ohm resistor and the DCR of the tweeter very small difference on a percentage basis.

Once again Pete, thanks.

If I go that route I may just order from Erse anyway (and will go with 18 ga). Zalytron has a $50 minimum and their primitive website makes it difficult to figure out how to order. Guess you have to order by phone. Another good thing about the Erseaudio site is they have a .o7 inductor, which is even closer to the original .065 mH value (if that matters).

The refoam job is finished. Came out quite well if I do say so. Still don't agree that the Masonite-ring version is "easy" compared to more conventional designs, but not as bad as I had feared.

Kent