AR-14 crossover schematic

[Kip]

Not being able to find a schematic diagram for an AR-14, I've attempted to create one based on the physical layout spec.

Used qucs to make this - AFAIK it doesn't directly support 3-position on-off-on switches so I represented that switch with two SPST switches.  Also the "W" and "T" resistors are there as very rough approximations of the drivers.  They (and the attached voltage meters) allowed me to run sims to look at response curves.

I thought I'd post this here in case anyone might benefit from it.

Hopefully my translation from physical layout to circuit is correct.

 

[ligs]

Can you run SIMs first with both W and T as 8 ohms and then 6 ohms. My pure guess is the 6 ohms is closer to the real DCR of AR drivers. 

[djcheung]

Is this what you are looking for ?

 

[ra.ra]

The parts list does not show any 8 ohm resistors as shown in Kip's drawing - - are these parallel resistors attached directly at the driver terminals?

[owlsplace]

51 minutes ago, ra.ra said:

The parts list does not show any 8 ohm resistors as shown in Kip's drawing - - are these parallel resistors attached directly at the driver terminals?

Looks like the resistors are there to simulate the drivers.

[ra.ra]

D'oh!.....OK, I get it now, I see the W and T..... a little confusing, not quite a true schematic.

[Kip]

8 hours ago, ligs said:

Can you run SIMs first with both W and T as 8 ohms and then 6 ohms. My pure guess is the 6 ohms is closer to the real DCR of AR drivers. 

Sure, if you'd like.  Did you want to see the graphs here?  I did run sims but didn't bother posting them, because I figured representing the actual drivers with just resistors was too simplistic and might be misleading.

But happy to do so if you're interested.

[Kip]

8 hours ago, djcheung said:

Is this what you are looking for ?

 

Not really looking for this...already had it - this is what I based the schematic on.

[Kip]

4 hours ago, ra.ra said:

D'oh!.....OK, I get it now, I see the W and T..... a little confusing, not quite a true schematic.

Yup, "W" and "T" are not really part of the circuit (unless you can visualize them as speakers).  Neither are the meters 

I stuck them in there so I could generate some frequency vs voltage curves.  But the rest of the circuit (I hope) is accurate in terms of the pictorial diagram, which is all that I could find.

Thanks.

[ligs]

6 hours ago, ra.ra said:

The parts list does not show any 8 ohm resistors as shown in Kip's drawing - - are these parallel resistors attached directly at the driver terminals?

 

12 minutes ago, Kip said:

Sure, if you'd like.  Did you want to see the graphs here?  I did run sims but didn't bother posting them, because I figured representing the actual drivers with just resistors was too simplistic and might be misleading.

But happy to do so if you're interested.

All sims are approximation but  they are useful nontheless.

[Kip]

Just an aside about crossovers - last night I opened up one of a pair of KLH Model 20's I have (unfortunately with a flood-damaged cabinet) and was surprised at how the crossover compared with this one.  It looked...well...cheap.  Only a couple of small caps and resistors.  I didn't see any chokes at all.  And it appears that the woofer is simply wired directly to the input connection (an RCA jack).  That doesn't seem right.  Got me to wondering if a woofer's voice coil in some way acts as it's own inductor to reject high frequencies.  Still, compared to the AR crossovers I've looked at, this KLH one seems pretty lame.

[Kip]

10 minutes ago, ligs said:

 

All sims are approximation but  they are useful nontheless.

Right, then.  I'll run a few sims and post here.  Both 8 and 6 ohms.

[owlsplace]

1 hour ago, Kip said:

Just an aside about crossovers - last night I opened up one of a pair of KLH Model 20's I have (unfortunately with a flood-damaged cabinet) and was surprised at how the crossover compared with this one.  It looked...well...cheap.  Only a couple of small caps and resistors.  I didn't see any chokes at all.  And it appears that the woofer is simply wired directly to the input connection (an RCA jack).  That doesn't seem right.  Got me to wondering if a woofer's voice coil in some way acts as it's own inductor to reject high frequencies.  Still, compared to the AR crossovers I've looked at, this KLH one seems pretty lame.

AR made some Scottish crossovers also. Here is the AR-8 crossover from the archives and I think some of the other 2-ways went with just a single cap:

Yeah, voice coils exhibit inductive and capacitive reactance plus resistance forming a series low-pass filter.

Roger

[owlsplace]

18 hours ago, Kip said:

Used qucs to make this - AFAIK it doesn't directly support 3-position on-off-on switc

Clue me in, what is qucs?

3-position on-off-on switch would be a SPDT switch or, single pole, double throw switch.

Roger

[Kip]

3 minutes ago, owlsplace said:

Clue me in, what is qucs?

3-position on-off-on switch would be a SPDT switch or, single pole, double throw switch.

Roger

I might be wrong, but I don't think an SPDT is the same as on-off-on, which has a center position where nothing's connected.

Here's a link to qucs.

Cheers!

[owlsplace]

3 minutes ago, Kip said:

I might be wrong, but I don't think an SPDT is the same as on-off-on, which has a center position where nothing's connected.

Here's a link to qucs.

Cheers!

Thanks for the link.

Yeah, should have mentioned "center off" ... here is a DPDT with center off:

https://www.amazon.com/Heavy-Duty-Toggle-Switch-Center/dp/B001FRE1E8?ie=UTF8&SubscriptionId=AKIAILSHYYTFIVPWUY6Q&camp=2025&creative=165953&creativeASIN=B001FRE1E8&linkCode=xm2&tag=duckduckgo-ffnt-20

Roger

[Kip]

6 minutes ago, Kip said:

I might be wrong, but I don't think an SPDT is the same as on-off-on, which has a center position where nothing's connected.

Here's a link to qucs.

Cheers!

Whoops, I sit corrected...apparently there are multiple types of "SPDT" switches...some have 3 positions (center = OFF) and some don't, but according to the catalog I'm looking at they're all "SPDT" switches.  My bad!

[ra.ra]

Gotta admit, this stuff confuses me, too, and I'll forever be sitting in the back row of the remedial class for Crossover 101. Nonetheless, here is a great diagrammatic explanation of this 3-position switch prepared by Rlowe for an earlier thread about the AR-6 (B) crossover. It is the same switch found in the AR-8 or AR-14, and is a SPDT, on-off-on configuration. It may take a minute to correlate the various diagrams, but you can see that in the center "decrease" (or OFF) position, the current flows thru both resistors for maximum attenuation while the switch sits in 'dummy' mode idling on the 2 terminal of the switch, not connected to either the 1 or 3 terminal.

[Kip]

Here are some plots of qucs sims for this circuit as previously suggested.  One set represents the drivers as 8 ohm resistors, the other as 6 ohms.

 

[djcheung]

Sorry for misunderstanding your question.

' Not being able to find a schematic diagram for an AR-14 '

[michiganpat]

17 hours ago, Kip said:

Just an aside about crossovers - last night I opened up one of a pair of KLH Model 20's I have (unfortunately with a flood-damaged cabinet) and was surprised at how the crossover compared with this one.  It looked...well...cheap.  Only a couple of small caps and resistors.  I didn't see any chokes at all.  And it appears that the woofer is simply wired directly to the input connection (an RCA jack).  That doesn't seem right.  Got me to wondering if a woofer's voice coil in some way acts as it's own inductor to reject high frequencies.  Still, compared to the AR crossovers I've looked at, this KLH one seems pretty lame.

well, there's the acoustic response of the driver that you have to account for.  ideally the acoustic response of the drivers would be that you wouldn't need to add any crossover components into the signal path.  The KLH woofer, much like the AR7, 18 and it's later variants, as well as Winslow Burhoe's "modules" in the EPI/genesis lines run the woofer wide open  with no inductor, since they have a nice, smooth 4th order roll-off naturally....

[lARrybody]

Here is the rebuilt crossover on a AR18S speaker. Spring loaded clips replaced with binding post, 5uf electrolyte replaced with Dayton poly. That is it.  Simplicity.