AR9's and bass response

[Guest jbangelfish]

I recently purchased a pair of vintage Teledyne AR9's and overall am very pleased with their performance. They were refoamed and new grills were put on by Wisconsin Reconing in West Allis WI sometime in the last 2 years or so. They appear as new.

My question is about the bass response that I am getting from them as it seems soft or subdued as compared to other speakers that I have owned. The positioning seems to be very important and could be my only problem. I have moved them around with some improvement as at first they seemed too focal. Moving them wider apart and nearer to side walls made a huge improvement in what I was getting from them. The narrow focus widened out and bass improved. It still is not what I expected from them as these speakers should reach lower than anything that I have ever owned. I'm not looking for overwhelming boominess, just wondering if I'm missing something.

I've even wondered if in rebuilding them, that they somehow got wired out of phase. Is there a simple test that I can perform to tell me if the woofers are in phase? I'd rather not take them apart to check wiring as the book states that the seals around the speakers have to be replaced if this is done. I am reasonably certain that all speakers are the originals as they look correct compared to photos.

The listening room is fairly large at 25 X 15 X 12 but I would not expect this to be too large for them at all. I should have plenty of power with my Parasound HCA 2200 II amp as it has 385wpc in 4 ohm and showed great bass response in the past with 4 Peerless 12's as bass speakers. They were all forward firing but I would not expect this to make such a pronounced difference as I'm experiencing. Anyone with any thoughts on this, I'd love to hear from. Will also be inquiring about biamping but saving that for later.

[ar_pro]

Congratulations on your good fortune, Bill...the 9's are an outstanding system that should serve you well for many years.

Your room size and available amplifier power are well within the norms for excellent results from these speakers...that said, it's unusual that you'd find the 9 lacking in bass response, as the design has a SUBSTANTIAL low-frequency capability. Assuming the drivers are OK, and weren't somehow adversely affected by their re-foaming, checking for correct phasing would make good sense. You need only remove one woofer to do this, and a replacement seal or caulk is a cheap and easy procedure.

I've used an old Heathkit IG-18 audio generator to supply test frequencies to speakers under repair, or to evaluate a speaker's response in a given location...it's a useful tool to literally check a system's response in 1Hz increments.

[Guest dogmeninreno]

There is a simple test to assure that the woofers are "in phase" with each other. First remove the amp leads. Take a AA battery and with a piece of wire on the + and - of the battery, connect the wire to the + and - of the 9. Unhook one side of the battery and keep tapping it to the battery terminal while watching the woofers, They should move out not in on each application of the battery. I am not sure but this may work on the lower (8") mids too. Be sure they all move "out" on application of the battery! Also be sure that your amp wires are connected amp + to speaker + on both speakers...Hope this resolves the problem. The 9's are awsome when driven and connected correctly..Good luck..Dale in Reno...

[Guest dogmeninreno]

>Congratulations on your good fortune, Bill...the 9's are an

>outstanding system that should serve you well for

Ar-pro brought up a good point as always. Checking for a good acoustic seal is very important..follow his instructions..Dale

[Guest jbangelfish]

I may try the battery test as I'm not anxious to take a woofer out yet. I have already double checked that I was in phase with speaker wire at the amp and speaker terminals, I checked this first as I've mixed them up before.

For the most part, I am amazed at what I hear from them but I'm sure that the bass should have more presence. I'll report my findings with the battery test. Thanks again,

[soundminded]

Bill, nice to see you made it over here. Sorry you aren't getting the full benefit of your new AR 9s. Mine were store demos and had all of the drivers replaced by the dealer before I took delivery. After several years of not being totally satisfied, I got a copy of the schematic and took mine apart. A lot of the drivers were wired wrong-out of phase. Yours could be too. First thing I would do and was going to suggest was the AA battery test to make sure all of the woofers are operating and in phase. We've had discussions of just how tight these cabinets have to be but it would take a pretty lose driver IMO to substantially affect the bass to the extent you describe. Mine have a gasket between the woofer frame and the wood cabinet to make a seal. Reading the instruction manual available as a pdf download at this site (you definitely want a copy of this and especially the crossover schematic) you need to have the speakers located within a couple of inches from the back walls and in my experience, at least a couple of feet from the side walls. Too close to the side walls and for some reason in my room the bass is very attenuated. Did you check to make sure that the woofers are operating at all? Be sure the links between the woofer sections and the rest of the speaker are connected. Try operating just the woofers alone and verify that all of them are working. There is no evidence or reason to believe that any of them are damaged from what you have said so far. When properly operating and in phase, these speakers should produce some of the most powerful, deepest, and low distortion bass of any speakers, at least compared to the ones I've heard.

Good luck.

[Guest jbangelfish]

All woofers are in phase. I checked them by listening to a CD and feeling with my index finger that on the onset of a bass note that they were pushing forward. This was enough to convince me that they are in phase. I hate touching a speaker but I made sure that my hands and fingers were very dry and clean.

Anyway, I noticed that by moving further away from my listening spot, the bass became more pronounced. Anyone familiar with this phenomenon? My placement is probably horrible. There is too much clutter in the room and I cannot move them closer to the rear wall as my components are behind the right speaker. The left channel cannot even reach the wall, due to obstructions. Unfortunately, the left speaker has to reflect off of a console TV which is in the middle of both. I will rearrange the entire room if I have to but it is not my stereo room which is yet to be completed.

Another consideration is my amplifier. When I bought the first one, I was impressed by it's clean and detailed nature but felt that it lacked the kick that I was expecting from such a powerful amp. So, I bought another one and used them bridged mono. When I did this, I thought that I had never heard better. This brings an enormous amount of power, an almost ridiculous amount, even by my standards, and I'm a power nut. So, I call them my Polish amps, it takes two to do the job of one.

So, my next question is how to biamp with two stereo amps without bridging them mono. The AR9 book states that each section of the speakers can handle 400 watts of power for a total of 800. If I bridge mono, I am at 1000 watts per channel at 4 ohms and I don't want to damage anything. If I am able to use both amps in stereo mode, I have 385 watts per section X 4. I just don't know how to wire them for this. The Parasound books tell how to biwire and have the extra terminals for this, the AR book tells how to biamp but I can't find how to do so with two stereo amps. Any ideas? Thanks,

[ar_pro]

There's a nice thread somewhere regarding the AR9 in biamp mode. It's pretty straightforward - with two identical stereo amplifiers, you'd use one amp for the left speaker, and the other for the right (this is commonly referred to as "vertical biamplification"). After disconnecting the 9's jumpers, attach Amplifier One's Channel A output to the Left Speaker's upper range connections, and the Channel B output to the Left Speaker's woofer section. Repeat the connections for Amplifier Two and the Right Speaker. Unless your preamp has more than one pair of left and right outputs, you'll also need two "Y" connectors (one RCA jack to a pair of RCA plugs) to connect your left & right preamp cables to the amplifier jacks. I've used this configuration with a pair of Adcom 555II amplifiers, with excellent results...it is also possible to insert a LF equalizer (Audio Control, among others has offered equalizers that permit fine-tuning the extreme low end) into ONLY the woofer section of the 9, providing more control over the system's bass output, while avoiding interaction with any frequencies above those handled by the woofers.

Bill, you Parasound's rated output should be right on the money for these speakers...if they sound bass-shy, I doubt that it's from a lack of power.

[Guest Bret]

>Anyway, I noticed that by moving further away from my

listening spot, the bass became more pronounced. Anyone

familiar with this phenomenon?<

Bill, I'm certainly not the expert some here are, but I would suggest that you do the battery test.

I don't know that I know all the right terminology, but there are "standing waves" and places of cancellation caused my most listening rooms, but asymetrical placement out to help with that.

The usual "listening" test for out of phaseness (phaseness?) gets a little tricky with four woofers. With two woofers you do the obvious - stand in front of the left speaker and move slowly toward the right speaker. If the bass is loud in the left, diminishes as you get between them, and then gets louder as you move to the right, that's about as clear as it gets that the woofers are out of phase.

I suspect it is very possible for each cabinet to have the woofers wired in-the-same-phase and yet have one set of woofers out-of-phase to the rest of the system. That ought to have some fairly odd effects with side-firing woofers and an 8" midrange driver crossed-over as low as 200Hz. So the battery test would not only confirm that each cabinet is in-phase with itself, but that both cabinets are in phase with each other.

I've had my 9s on all sorts of amplifiers. The bigger wattage amplifiers "open them up" but in no case, even when they were badly, badly underpowered and placed badly would you doubt the bass.

If I were experiencing what you are experiencing, I probably wouldn't be satisfied until I did the battery test and/or pulled a driver and visually confirmed in-phase wiring.

Bret

[Guest Bret]

>I have 385 watts per section X 4.<

Sorry to have posted twice, but I just caught this -> I believe you said your Parasounds are 385/channel into 4 ohms. If you biamp the 9s each section (upper and lower) are 8 ohms apiece. Also you want to be very careful about bridging your amplifiers. As I understand it, when you bridge an amplifier and put a 4 ohm load on it, each mono amp (left and right) "sees" half the impedance meaning you might be showing only 2 ohms to each amp. Probably not a great idea for most amplifiers, even those that can take it. Maybe yours aren't wired that way, but I'd want to read the owner's manual twice.

Now, having said all that I'll tell you I don't think it'll matter much. The difference between 200-225 watts and 385 watts is not that big of a deal. But more importantly, the 9 is a fairly "difficult" load for an amplifier to drive. What you lose in wattage by bi-amping you might gain in "control" by splitting the sections.

I can drive my speakers to near pain-threshold levels with a quality 100w/channel amplifier before it shows clipping on the meter - certainly louder than I would ever listen for any period of time and I'm a bass nut and a volume freak.

Bret

[soundminded]

Frankly, I would not rely on your phase test. The battery test is the only way short of removing the drivers and verifying that the wires are connected correctly according to the color coding on the wiring diagram.

To verify that there are no serious air leaks, turn off your amplifier, remove the grill cloths from both of the woofers and gently and lightly push the cone of one woofer in very slightly and observe that the other woofer instantly moves out by the same amount. If this does not happen, there is a very significant air leak which will compromise bass performance. (This will not affect the 8 inch driver because it is in a seald sub enclosure.)

One thing you can do is set all three program switches to -6 db. This effectively boosts the deep bass by 6 db while maintaining "flat" response above 200 hz. As I recall, those are the recommended settings in the instruction manual anyway. The other settings are for situations where less power is available.

It is completely unnecessary to bi-amplify your spekers or bridge your amplifiers. Either your Parasound or your Crown DC300 amplifier has far more than enough power and low frequency capability to drive these woofers to thunderous levels.

If there are no problems with phasing, and nothing else works, it is time for an equalizer.

If you decide that you don't like these speakers after all else fails, let me know. I might be willing to buy them from you shipping cost and all. You can never have too many AR9s.

[Guest jbangelfish]

Many thanks to all of you. Finally home from work so I can try some more tests. I also have a test LP which I'll use after the other tests that you all have suggested.

As for bi-amping, I like the idea that the system will convert to 8 ohms as it's easier on the amps and I won't have such a ridiculous amount of power. I don't dare bridge mono as they are just too strong for most speaker systems this way.

I'm still baffled but have many things to try. Thanks again and I'll let you know my findings.

PS, this site is a lot more friendly than Audio Review, where I usually hang out.

[Guest Nigel]

>If you biamp the 9s each section (upper and lower) are 8 ohms

>apiece.

This is NOT correct !!!

The woofers will show approximately 4 ohms up to around 200 Hz, and then the impedance will rise dramatically above that frequency. The woofers are the part that is tough on the amplifier.

The mid/upper section will show high impedance below 200 Hz, and drop to around 4 ohms for most of the rest of the audio spectrum.

In both cases, there will be peaks much higher than nominal.

Nigel

[Guest Bret]

>If you biamp the 9s each section (upper and lower) are 8

ohms

>apiece.

This is NOT correct !!!<

Okay, fine, teach me.

If I take a signal generator and sweep frequencies the woofer cabinet at 30Hz; we're about 8 ohms which retreats to less than 4 ohms at about 80Hz, then starts up. Great, I understand.

If I take a signal generator and sweep frequencies 200Hz on up, we're going to get into the 10+ ohm area before trailing off to anywhere from 8 to 4 ohms depending on if we have the attenuators in or not. Great, I understand.

If I take a polyphonic audio signal generator and hit the strapped cabinet with an 80Hz and 17kHz tones. . . now what? What keeps that from showing the amplifier less than 2 ohms, or would it and I'd fry an amplifier?

I guess where I am confused is that while I understand that if you used an electronic crossover and only fed the bottom cabinet 200Hz down you'd be showing the amp 8-4 ohms. And if you did the same thing, only different, with the upper cabinet you'd show the amplifier 10 - 4 ohms, depending.

But if I play pink noise into the woofer, doesn't the crossover shed the "extra" frequencies and hold the impedance?

If you then strap those two cabinets together and throw pink noise at them. . . I guess I'm asking how the crossover could "know" to hold the impedance to one thing or another.

Bret

[Guest Nigel]

>But if I play pink noise into the woofer, doesn't the

>crossover shed the "extra" frequencies and hold the

>impedance?

No, as the frequency increases, the circuit's impedance goes up. The circuit in this case includes the drivers which can be modeled as DC resistance plus inductance, in addition to the inductors (which have DC resistance too).

Re: two tones into a speaker with a crossover network, the low frequency signal "sees" a low impedance path through the woofers, and high impedance everywhere else. The high frequency signal "sees" a low frequency path through the tweeter, and high impedance everywhere else.

Nigel

[Guest Bret]

>Re: two tones into a speaker with a crossover network, the

low frequency signal "sees" a low impedance path

through the woofers<

I'm slowly getting there:

Let's take an easier example for me. Say an AR 14. I play a 100Hz tone through the speaker. The *frequency* is "allowed" to pass to the woofer at hypothetically 6 ohms. All other paths for that electricity are blocked (filtered-out) by the crossover. Because the amplifier cannot see a blocked frequency at all, it reads this situation as a 6 ohm load.

Now I take TWO AR-14s, parallel them, play a 100Hz tone through them and *both* allow the electricity make a circuit through the woofers at 6 ohms.

The AMPLIFIER "reads" this situation as 3 ohms, right?

However, if I were to use ONE AR 14 as a tweeter only and one as a woofer only (removing the other driver), then the 100Hz tone would pass through ONE woofer and be blocked at the other speaker so the amplifier would still see 6 ohms.

So, in the case of the AR-9 the impedance, not of both, but of either cabinet is "nominally" 4 ohms. But because the signal cannot pass through both cabinets (upper and lower) only the resistance of ONE cabinet is "seen" by the amplifier.

Therefore, if I played a 10kHz tone into the woofer section of an AR-9 the impedance seen by the amplifier would be "infinite" because the circuit never gets completed through a driver and is not shunted off into a resistive load, it is just effectively switched "off" at the crossover. No circuit.

SO - if I play pink noise into an AR-9 that's strapped, the upper-range signal gets "passed" at 4 ohms and the lower signal gets passed at 4 ohms, but the amplifier only sees the 4 ohms at any given frequency, not the sum of all resistances at all frequencies?

IF that's right, I'm going to feel a bit like Eliza Doolittle in My Fair Lady and break into song; right after thanking you very much for teaching me more than a bit about how a crossover works.

I knew there was some reason I didn't try to build speakers.

Bret

[soundminded]

"I guess where I am confused is that while I understand that

if you used an electronic crossover and only fed the bottom

cabinet 200Hz down you'd be showing the amp 8-4 ohms. And if

you did the same thing, only different, with the upper

cabinet you'd show the amplifier 10 - 4 ohms, depending."

"But if I play pink noise into the woofer, doesn't the

crossover shed the "extra" frequencies and hold the

impedance?"

The drivers are each connected through what amounts to a filter network and all of them are in parallel. Each filter network has a low impedence at the frequencies for that driver only and a high impedence for frequencies intended for the other drivers. As an example, take a two way speaker. The circuit to the woofer has capacitors and inductors arranged so that the impedence is low at low frequencies and begins increasing at the crossover frequency becoming progressively higher at high frequencies. The crossover elements for the tweeter do just the opposite creating a low impedence path to the tweeter at high frequencies and a high impedence path at low frequencies. This is how low frequencies are kept out of the tweeter so that they don't damage it or cause distortion and high frequencies are kept out of the woofer so as not to cause distortion there either. With three and four way systems, the midrange drivers have "bandpass" filters which create a low impedence path for the frequences each driver is intended to reproduce and high impedence path for frequencies outside (above and below) the intended range. The higher the order of the crossover network, the more quickly the impedence changes as you move away from the crossover frequencies.

When you measure the impedence of all of the drivers and crossover elements, you are actually measuring the effect of the different elements in parallel. So for example, if you measure at 50 hz, the woofer circuit with its crossover might show 4 ohms, the midrange, 50 ohms, and the tweeter, 500 ohms which is still about 4 ohms, If you measured at 1000 hz, the woofer circuit might be 50 ohms, the midrange circuit 4 ohms and the tweeter circuit 50 ohms which overall is still about 4 ohms. If you measured at 10 khz, the woofer circuit might be 500 ohms, the midrange 50 ohms and the tweeter 4 ohms which overall is still about 4 ohms.

When you bi amplify a loudspeaker like AR9 using an electronic crossover, two amplifiers, and removing a link at the speaker, each driver still is connected through its crossover filter elements. The amplifier connected to the woofer will see 4 ohms at 50 hz but above its crossover frequency of 200 hz it will see a high impedence. The amplifier connected to the rest of the speaker will see a high impedence at low frequencies below 200 hz but above the crossover frequency of the lower midrange, it will see 4 ohms due to the combined effect of the lower and upper midranges and tweeter as I explained above.

I hope this helps clear it up.

[tysontom]

>All woofers are in phase. I checked them by listening to a CD

>and feeling with my index finger that on the onset of a bass

>note that they were pushing forward. This was enough to

>convince me that they are in phase. I hate touching a speaker

>but I made sure that my hands and fingers were very dry and

>clean.

You may have resolved your low-bass problem by now. But in any event, I have to agree with others here that you really can't make an assessment of phase without doing the battery test. What I have done through the years is to have a flashlight “D” cell (you could use an “AA” but don’t try using a 9-volt battery) battery in which I have soldered a fairly long section of wire on the negative side, and another section of wire to the positive side. This, therefore, is a known quantity. On the AR-9, as mentioned by Soundminded and others, you would want to disconnect the amplifier connection to the speaker, and get someone to watch each woofer cone on each speaker as you touch the negative and positive wires from the battery to the appropriate negative and positive terminal on the AR-9. Each time you touch the positive battery lead to the positive AR-9 terminal, each woofer cone should move *out* away from the speaker cabinet. If all four woofers do this okay, you are basically in phase so long as you connect each speaker’s terminals to the amplifier for both left and right channel the same way, with the red or (+) terminal going to the red or hot amplifier lead, and black (-) going to the amp’s negative or black terminal. The important thing here is to do the same thing to both speakers.

It is remotely possible that the electronics are wired out of phase somehow, but this is highly unlikely. You could reverse the amp leads on one speaker to see what happens. Usually, out-of-phase woofers have weak bass that is “moving” around the image with what appears to be lots of standing waves, etc. Back in phase is an obvious improvement. This condition, however, is extremely rare. Do the speaker-woofer phase test first with a battery. You could have just one woofer out of phase and it would sound terrible, and that speaker would also *easily* overload since the cones are not pushing and pulling against one-another within the sealed cabinet, and they will bottom very easily if they are out of phase within a single cabinet.

--Tom Tyson

[soundminded]

Determining whether amplifier connections to the speakers are in or out of phase with each other is a very simple test. Play a monophonic source or switch the preamp to mono. The sound should appear dead center between the speakers and sharply focused in one location. Face them towards each other and stand between them if you are not sure. If it is diffuse instead, the leads from the amp are out of phase. An internal phase wiring error in an amplifier is very very unlikely. In some models, this would mean a dead short to ground on one channel rendering it inoperative.

[Guest Bret]

>I hope this helps clear it up<

ALMOST

>When you measure the impedence of all of the drivers and

crossover elements, you are actually measuring the effect of

the different elements in parallel.<

Here's where I am getting hung-up.

I was using the bass cabinet for simplicity's sake, but let's take the case of the upper cabinet to put my education to bed.

IF I play pink noise through the upper cabinet *some* signal is passing through all the drivers. SO, if a signal passes each driver (the 8" @ 8ohms, the upper mid at 4ohms, the tweeter at 4ohms) then each driver is acting as a resistor.

1/Rt= 1/8+ 1/4+ 1/4; 1/Rt=5/8; Rt=8/5, Rt= 1.6 ohms.

Ok, add tiny bit for the high impedance crossover areas, maybe 1.7- 1.8ohms.

If I can get a handle on why that's not true, I'll feel educated and can go quiet.

Bret

[soundminded]

Maybe I'm not making myself clear. Yes each speaker driver can be seen as a resistor in series with an inductor. Between the amplifier and each driver is a series of capacitors, inductor, and even a resistor or two (except for the woofers-no resistors there.) The purpose of these added components in each case is to create a filter which is a frequency selective circuit which is low impedence for only the frequency range of its respective driver and high impedence outside of that range. If you looked at each one separately, a graph for the impedence as a function of frequency would be in the shape of the letter U for the midranges a Letter L for the tweeter, and a backwards L for the woofer. Draw a graph and try it. The vertical axis is impedence, the horizontal axis is frequency. The first section is for the woofer. Its impedence is a straight line across the bottom and when it reaches 200 hz, it goes almost straight up and keeps going higher across the rest of the graph. The next section is for the lower midrange. It starts high, then when it gets to about 200 hz, it falls to near zero, stays there until 1.5 khz where it starts going up fast and staying there. Then next section is for the upper midrange which starts high and as it reaches 1.5 Khz, falls to near zero, stays there until it reaches 7 khz where it starts going up fast again. The final section is for the tweeter which starts real high and at about 7 khz falls to almost zero and stay there for the rest of the graph. Draw each one in a separate color if that helps. Each of these represents a different cluster of inductors and capacitors for a particular driver. Download the circuit for the AR9 crossover and look at it, that might help. You can see the amplifier input on the left, the jumpers between the woofer section and the rest of the speaker system, the drivers on the right, and each section of the crossover between them. When you measure the system as a whole, you are combining all of these at the same time.

Any better now?

[Guest jbangelfish]

No tone controls, no mono switch. I rarely used these things so thought they would not be important but I guess I probably used them more than I thought. For a serious listening session, it would be loud and everything flat. It might be nice to have some of these features back, bass boost for low volume or being able to tone the treble down etc. If I decide to stick with the equipment that I have, I may invest in an EQ, which I never thought I'd hear myself say. I don't like any extras in the circuit, no fuses, nothing.

Anyway, I'm sure that my earlier concerns were unfounded. Can't be sure about the first amp, might need to have it checked out. I'm getting bass that shakes the house but poor placement and obstructions keep it from reaching the sweet spot. Need to work on that. Thanks,