Ar11 : need crossover

[Guest kamipiccolo]

hello. It's the first time i'm writing in this Forum.

This is Marco 25 y.o.from Italy.I like really much marantz and Ar vintage.

I have just found a couple of Ar 11 that i would like to fix.

Both crossover are ko and i'd like replace tham with original or new and better crossover. On the web i have just found a guy that is going to sell ( 40$ ) me these crossover in picture. What do u think?

Are induction coils and capacitor original? Where can i find a right and new an upgrade crossover for my ar11? ( maratn 1200b will drive them)

thanks for all your attention

best greetings from Italy

kamipiccolo@libero.it

[dynaco_dan]

>hello. It's the first time i'm writing in this Forum.

>This is Marco 25 y.o.from Italy.I like really much marantz and

>Ar vintage.

>

>I have just found a couple of Ar 11 that i would like to fix.

>

>Both crossover are ko and i'd like replace tham with original

>or new and better crossover. On the web i have just found a

>guy that is going to sell ( 40$ ) me these crossover in

>picture. What do u think?

>

>Are induction coils and capacitor original? Where can i find a

>right and new an upgrade crossover for my ar11? ( maratn 1200b

>will drive them)

>

>thanks for all your attention

>

>best greetings from Italy

>

>kamipiccolo@libero.it

>

Welcome Marco;

I am not an expert, Marco, but I have read a lot on this website about capacitors and their deterioration.

Anyone buying an original crossover will be buying 25 plus year old caps and that may not be a very good investment.

If you are in need of everthing else then buying a cheap used crossover, with the intention of changing to maybe Solen or other decent quality polpropylene caps might be in order.

The induction coils should normally not be an issue.

Please wait for other members to write to you, Marco.

Your existing crossovers may only need replacement capacitors as is.

Good luck and please keep us up to date with your decisions.

[Guest Bret]

>? Where can i find a right and new an upgrade crossover for my ar11?<

You can put new caps in them, but do *not* change the inductors. Do not "improve" the inductors. Use the original inductors!

Bret

[rrcrain]

Other than the fact that replacing inductors makes for a marginal at best, and none at the worst, what is your rational for not replacing them? New inductors that are wound properly tend to be more repeatable in both resstance and inductance compared to the old method of winding.

[Guest Bret]

>New inductors that are wound properly tend to be more repeatable in both resstance and inductance compared to the old method of winding.<

The repeatability or uniformity has nothing to do with it. Matching, exactly, does. Therefore, if the inductor isn't broken (highly unlikely unless hit my lightning or a hammer) there is no reason to fix that which isn't broken. It is not possible to "improve" on the original if the circuit is to function as designed.

The original inductor is more important in the proper function of the crossover than are the capacitors' secondary characteristics by several orders of magnitude. I'll leave the whys to those who can explain better, more technically, and more thoroughly than I can.

Sorry I have to leave it like that, but I do.

Bret

[rrcrain]

Improvement is in the ear of the beholder. Its also well known that crossovers differed enough that different pairs, let alone different speakers, were known to sound differently.

Dollar for dollar, replacing inductors isn't a good investment compared to replacing worn out caps. That to me is the best reason to recycle the old inductors PROVIDED they are of a good quality to begin with.

[RoyC]

I agree with Bret.

John O. and I have been comparing notes on this very issue in relation to the AR-3a. An often overlooked factor when choosing inductors to replace those in a previously engineered (successful) design is the need to maintain the impedance they provide to the circuit. A number of issues including resonance peaks, crossover points and overall tonal balance can be affected by using inductors of the right value but wrong impedance.

The AR inductors of that era are wound with 17 ga wire...a size not typically found in the replacement marketplace. Different gauge wire, iron core, steel laminate and copper foil inductors will all have different resistive values compared to the original.

The only logical reason to replace an AR inductor from that era is if it is found to be out of spec. (I have stumbled on a couple of very bad AR-3a #9 coils along the way).

Roy

[Guest Bret]

>Improvement is in the ear of the beholder.<

Uh. . . no, not really. We're not talking about "taste" (for which there is no accounting). I think that may be the first thing you've ever said that I wanted to argue-with.

>Its also well known that crossovers differed enough that different pairs, let alone different speakers, were known to sound differently.<

Yes, I'm one of the ones who pointed out that things changed and others didn't and that the changes were audible and material yet compensations weren't made. Just the change from the white to black tweeters in 11s and 10pi's made a material sonic difference. I may have even gone off on a rant about it.

We both know that what you said about changes is true, and yet I stand by my statement.

>Dollar for dollar, replacing inductors isn't a good investment compared to replacing worn out caps.<

I don't think any of us would argue with that. I certainly wouldn't even if I didn't hold my new-found inductor opinion.

>That to me is the best reason to recycle the old inductors PROVIDED they are of a good quality to begin with.<

Absolutely. But if replacing the "good" inductors with "great" inductors changes the way the crossover ***works*** (not "how well" but "how") you've screwed-up the crossover. Inductance (mH) is not the only critical spec of an inductor.

Call me names or whatever, but for personal reasons I don't feel at liberty to discuss this further.

I really am sorry I left it like this. I should have kept my mouth completely shut if I wasn't going to go all-the-way. I just wanted to prevent a mistake if I could. I'm learning to be quieter, though.

Bret

[r_laski]

>> I have just found a couple of AR-11’s that I would like to fix.

Both crossovers are ko and I'd like replace them with original or new and better crossover. On the web I have just found a guy that is going to sell ($40) me these crossover in picture. What do you think?

Are induction coils and capacitor original? <<

What do you mean by “Both crossovers are ko…”?

Those are AR-11 crossovers in your picture. I believe I saw these on e-Bay recently. The crossover on the right looks like it has all original parts. I would need to see a better picture of the crossover on the left. The purple capacitor and capacitor it is paralleled with, and the tweeter capacitor (mounted on top of the woofer inductor) may be replacements. I would need a closer look to see if these capacitors have AR part numbers.

They are original AR-11 crossovers from the earliest production AR-11s. These crossovers were on two Masonite boards. The larger boards, which are in your picture, would be mounted on the bottom of the cabinet. A smaller board, mounted on the back of the cabinet, would contain the switches, resistors, and binding posts (not shown in picture, but, they were nothing more than screws, washers, and knurled nuts).

These crossovers will only fit very early AR-11s. If they look similar to the crossovers in your AR-11s they will work. If however, your AR-11 crossovers are on a single board, mounted on the back of the cabinet, do not bother with the crossovers in your picture. In my opinion, the only useful parts on the crossovers in your picture are the inductors (if not damaged). The resistors and switches may be useful, but only if you were rebuilding the same version AR-11 crossover.

As I mentioned above, during production, AR changed the AR-11 crossover and consolidated all the components onto one board. The inductors for both crossovers are identical. The capacitor values are nearly identical, but the newer crossover used single capacitors instead of paralleled capacitors for the woofer and midrange. The switch / resistor networks are completely different. The wiring on the newer crossover is substantially simplified by eliminating the connector strip.

>>Where can I find a right and new an (or) upgrade crossover for my AR-11’s <<

Search this forum for discussions on rebuilding / upgrading the AR-11 crossover. You will find information on upgrading the AR-11 crossover with new components. This is a Do-it-Yourself project, unless you can find and take your speakers to a reputable speaker repair shop in Italy that can rebuild / upgrade your crossovers.

Rich