[scorpion]

Here is how two Augies placed low on two 40" (H) x 24" (W) baffles, Augies connected in parallel, simulate, LP 65 Hz 2nd order and Rumble filter at 20 Hz 3rd order , 2.83 volt applied :



You can get all Augie data by reading carefully on the Hawthorne forum (Qes = 1.02 and Qms = 8.9). To me it seems that trying to dipole-compensate only would exaggerate the response as Augie's  already high Qts = 0.92 will create a little hump of its own in the lowest end.

/Erling

[rythmik]

Here is how two Augies placed low on two 40" (H) x 24" (W) baffles, Augies connected in parallel, simulate, LP 65 Hz 2nd order and Rumble filter at 20 Hz 3rd order , 2.83 volt applied :
[snip]
You can get all Augie data by reading carefully on the Hawthorne forum (Qes = 1.02 and Qms = 8.9). To me it seems that trying to dipole-compensate only would exaggerate the response as Augie's  already high Qts = 0.92 will create a little hump of its own in the lowest end.

/Erling

I wouldn't worry about Qts=0.92. If you want to go back to Bob Carver's approach, the Qts is at least 1.5 or more like 2.0. That is when you don't need compensation.  In addition, a dipole sub is different from a sealed sub. In a sealed sub, a Q=0.5 sounds very clean and in a dipole sub, a Q value of 0.5 sound too dry.

[scorpion]

Hi Brian,

I certainly is in favour of yours and Danny's Servo Basses for OB and closed boxes. That is very interesting.

No the Qts=.92 of the Augie doesn't worry me. It has passed use with high flags, see: http://www.enjoythemusic.com/magazine/equipment/0107/diy_loudspeaker_project.htm for instance.

What I was trying to say with the simulation, is that it will essentially be ruler flat in response between 30 - 100 Hz used with gooberdude's crossover frequencies and settings on the typical Hawthorne sized baffle, thus not needing any further augmention other than level adjustment. Now this low bass is not really instrumental in our awareness of bass performance. It will be the frequencies, as Dick Olsher says, 100 - 200 Hz. Thus harmonics of low bass and fundamentals of the a bit upper bass spectrum.

I think there may be some confusion about what you call an OB-shelf setting in at 80 Hz. It would be very good if you just explained what you are doing in terms of shelving or 6 dB/octave dipole compensation. 

/Erling

[rythmik]

I think there may be some confusion about what you call an OB-shelf setting in at 80 Hz. It would be very good if you just explained what you are doing in terms of shelving or 6 dB/octave dipole compensation. 

/Erling

Hi Erling,

No problem. I went to Danny's place about two months ago and took some measurements on an OB sub. First is the close-mic measurement of the woofer right at the cone. Look how clean the measurement is.

This one already has a mild shelving built-in.  Next I did a far-field measurement at the  listening seating position. There are two plots: one is unsmoothed and the other is unsmoothed. The resolution of this measurement is 0.3hz. All of my measurements here are based on MLS (max length sequence). It is not a sweep. A sweep result will be questionable in a room with reflection. One can see, so-called room mode is made of a lot of smaller nodes, and the smoothed response is pretty clean above 200hz.   (BTW, keep in mind every room has room modes, even a music hall.  My Denon receiver's special effect include DSP to create room mode to mimic a music hall. I don't understand why people are obsessed with perfectly flat response at the listening position. I, on the other hand, am obsessed with how to get a flat FR at the woofer because that is how mics pick up sounds. Speakers are used to reproduce what mics pick up. And mics are not placed at listening positions.  But that is another topic)

What is interesting is the plot of transfer function. A transfer function is an abstract method to describe the input/output relation of a blackbox system (Erling, this is for other members). It enable us to analyze components in the audio chain one at a time.  In this case, the transfer function we plot uses close-mic measurement as input and smoothed far-field measurement as output.  In other words, it actually tells us if we assume the output at the cone (close-mic) is perfectly linear in terms of frequency response, what would we get at the listening position. For OB, we know there should be a 6db/oct increase up to the frequency calculated based on the girth of the enclosure equating a full wavelength (for instance, 10ft at 100hz). So next I plot this transfer function (the blue line is the "ideal" 6db/oct increase)


It is pretty close. Danny's room still have a room mode at around 30hz. And there is still a room mode below 5hz. But don't be concerned by that. So our shelving circuit is an inverse of this trend to create a 6db/oct "decrease". Since I need to limit the scope of this decrease without overloading the amplifier, I have chosen the decrease is only between 10hz to 80hz, like this one:


 

[scorpion]

Hi Brian,

Nice indeed, I think it is for me too. I can follow your reasoning quite well and I think it is of exellent significance for yours and Danny's OB Speaker on a specific baffle. And, mind you, I do not question this approach as a good approximation to any speaker or baffle. Just some speakers and some baffles might need a different approach.

But, indeed Brian, very good of you to go to this lenght in explaining your thoughts and method, Thanks ! 

/Erling

[gooberdude]

Thank you for the information Brian!


As a follow-up to my orig post, a few days ago i changed the wiring scheme for the auggie's and the sound is better.  With a daisy chain type parrallel arrangement, the bass is quite forceful.  But with a traditional parrallel set-up, the auggie's sound as they should...completely in sync with the full range drivers.


This amp is so damn flexible.  Settings for most rooms and any taste.

I've been playing around with the EQ.  It is effective and addictive.


Brian, will I be able to purchase and install the slightly different OB shelf that the Hawthorne plate amps will be equipped with?

[tyee]

Hey Matt
    I see we're back and forth between here and hawthorneaudio.com. Fun stuff!
Anyway, I am also wondering what is the specific shelf component(s) for the auggie. My original plug-in board has a 10uF cap installed and so does my 2nd board that Brian sent. I suspect that this cap determines the shelf.

What's the value on yours. Does it say 106K, which is 10 million picofards = 10uF. The K is just the tolerance = 10%

Tony

[rythmik]

Hey Matt
    I see we're back and forth between here and hawthorneaudio.com. Fun stuff!
Anyway, I am also wondering what is the specific shelf component(s) for the auggie. My original plug-in board has a 10uF cap installed and so does my 2nd board that Brian sent. I suspect that this cap determines the shelf.

What's the value on yours. Does it say 106K, which is 10 million picofards = 10uF. The K is just the tolerance = 10%

Tony

Tony/Matt,

That 10u cap is decoupling cap for the power amplifier section. It is also the only decoupling cap in the entire amp. The preamp section is DC coupled. The shelving is installed in a gain stage at the preamp. It is pretty effective for OB with narrow baffle. The shelving is to correct the 6db/oct slope resulted from cancellation, not for a particular driver. Unless Darrel goes back to what Bob Carver had done (used a driver with Qts value of 2.0 to mimic a shelving circuit), this should be good for most drivers. I don't think Darrel will ever use a driver with such a high Qts value. I won't. 

In terms of the new board for Tony, it was a mistake on my part. Yours first servo board has one cap with incorrect value (the small compensation cap should have been 220pf, reads 221).  I sweep the amplifiers before they go out and yours is the only one I didn't do.  To be safe, I sent you a new card that I swept. If you have a chance please send back the original servo board.

Matt,

In terms of your version and HA's version, the main difference is your shelving circuit is milder, only between 20hz and 60hz. If you know how to solder, I can send you a photo explaining how to do it and you can achieve a bit wider shelving slope. 

[tyee]

Hi Brian
  Thanks for the info, now I see that the value is different.

Have we decided on which way is best to wire the two Hawthorne augie woofers yet or should we just try both ways (daisy chain or true parallel) and use what we like best?

Tony

[rythmik]

Hi Brian
  Thanks for the info, now I see that the value is different.

Have we decided on which way is best to wire the two Hawthorne augie woofers yet or should we just try both ways (daisy chain or true parallel) and use what we like best?

Tony

Tony,

I would recommend true parallel to reduce the interaction.

Brian

[gooberdude]

Thanks Brian.  I'll be in touch later on...    I might mail it back for the repair if that's possible.


Tony -Wiring the auggies so each driver has its own set of sp cables running into the plate amp sounds best if you run a pair of auggies, 1 per baffle.

[tyee]

Hey Gooberdude/Brian
    Thanks for the tip. I have them wired daisy chain right now just because of convenience to do that. I need Darrel to build me a case for it with proper speaker connectors then I can run them true parallel. Matt, where have you got your level set to?

[gooberdude]

I run 4 difft sources, and most are around 1V i believe - none very strong.
For most applications at about 50-60% volume.

For what its worth, I wouldn't advise engaging the eq with 'em daisy chained.  I never really heard a diference with it on, and knowing what I know now, you don't want to over exercise the subs.   
They'll get plenty of exercise under normal operation with the daisy chain wiring.  hopefully you are enjoying it.           

Enjoy la-la land only for only a brief period if possible.  I think the bass in that configuration is groundbreaking & amazing, but its not the real deal when you have a pair of Auggie's.  Is a difft ballgame when each driver is wired directly to the amp.  MAC cables are righteous, a happy customer myself. 

With a true parallel witing set-up, the eq is quite effective.  Using Darrel's cables will enhance performance on a magnitude of adding the PEQ370.  not the same of course, but in terms of maximizing the Auggie's performance.   


Brian, is the additional OB slope responsible for letting the Auggie's play what seems to be lower frequencies than say a Parts Express plate amp?  no disrespect to PE & I apologize in advance if you've already answered this somewhere.   

Movie soundtracks and even digital cable TV elicit thunderous performance & sounds like I'm not missing much compared to boxed subs I've owned previously, in terms of low freq extension.  Of course the Auggie's can't really reach that low, mid 20's or so.  The PEQ370 closes the gap a little bit between OB subs and boxed sub performance, which was unexpected.  My speaker set-up is a bit strange, essentially (4) Hawthorne 15" woofers, and to have the sub not only blend but adhere rigidly to the performance level of the stellar Sterlings is a blessing.   

It is so nice to have OB bass like this combined with a truly cohesive musical picture, and a bit like owning a gigantic big $ salt water fishtank full of musicians. 


With the daisy chain wiring set-up Tyee, this low bass performance is non-existent.  That wiring scheme seems to favor the upper deep bass freqs (50-100), and play them with wicked gracefullness.  It kinda kills the imaging though.

Get the new wires, keep the old ones, and enjoy it both ways at will.
That totals about 1,262 difft combinations of adjustment on the PEQ370      


try listening with the OB shelf turned OFF.  With daisy chain, I liked it better OFF.

[tyee]

Hi Gooberdude
    Forgive me but which switch turns the OB shelf off? The EXT/12??

tyee

PS, I have the XLR version, was thinking about using XLR's in the future but I would have to buy another unit because this XLR version is only mono for XLR, but is stereo for speaker and line level inputs. This model does not have the EQ. built in.

tyee

[gooberdude]

NO.   On mine, the OB shelf is a little add-on printed circuit board on the inside of the amp, close to the transformer and caps, etc.  It is suspended up on a little bridge (shelf) off the main pcb about 1", and is a card that contains what appear to be resistors.  about 2" x 2" in size. 

The OB shelf has a tiny silver ON/Off toggle switch.  Mine also has writing on it, indicating the power status in relation to the switch's position.  The OB shelf is not the main x-over component.  It is the interchangeable feature of these amps that allows the mfgr to taylor the amp for its intended use.   


The EXT/12 is the main x-over setting.  To my ear, the EXT/12 setting sounds best.  Let your ear decide though.  There is more info about it at Rhythmik's website.


Issues like this are why an instruction manual would be helpful.  The Rhythmik amp is not exactly straightforward for those used to normal plate amps.

It is a steep and fun learning curve though. 

[rythmik]

NO.   On mine, the OB shelf is a little add-on printed circuit board on the inside of the amp, close to the transformer and caps, etc.  It is suspended up on a little bridge (shelf) off the main pcb about 1", and is a card that contains what appear to be resistors.  about 2" x 2" in size. 

The OB shelf has a tiny silver ON/Off toggle switch.  Mine also has writing on it, indicating the power status in relation to the switch's position.  The OB shelf is not the main x-over component.  It is the interchangeable feature of these amps that allows the mfgr to taylor the amp for its intended use.   


The EXT/12 is the main x-over setting.  To my ear, the EXT/12 setting sounds best.  Let your ear decide though.  There is more info about it at Rhythmik's website.


Issues like this are why an instruction manual would be helpful.  The Rhythmik amp is not exactly straightforward for those used to normal plate amps.

It is a steep and fun learning curve though. 

When Matt bought his unit, I wasn't really certain how it will be used, so I put in a switch (I have all sorts of add-on modules) so that Matt can later change to other configuration. Once we put a connector on the PCB, the function can be modified beyond imagination    Later on I was contacted by another gentleman and that was when I realized what was going on and I decided to keep the OB shelving circuit simple (meaning not switchable). The shelving circuit does make a difference in terms of output.  370WRMS for two OB subs is powerful enough to push those drivers to their full excursion capability. The only missing part is whether that excursion can be fully utilized. OB shelving circuit makes that happen. 

 
 

[kyrill]

Hi Brian

I received yr servo amps (2x) for the OB servo Gr-research woofers

is there a drawing for the enclosure of the amps?

As in in the non-OB context  the amps are part of the enclosure, in OB contexts there is none, the amps need their own enclosure.
I want to let them build by a local furniture maker
regards
K.

[rythmik]

Hi Brian

I received yr servo amps (2x) for the OB servo Gr-research woofers

is there a drawing for the enclosure of the amps?

As in in the OB context  the amps are part of the enclosure, as there is none, the amps need their own enclosure.
I want to let them build by a local furniture maker
regards
K.

I don't have a drawing for the enclosure. I can come up with one. However, I would like to make sure you will use two sets of binding posts for the connection: one for driver coil and one for sensing coil on the amplifier enclosure.

[kyrill]

of course

after summer vacation i hope to finish my setup somewhere in september.

[Bob in St. Louis]

Wow, how did I miss THIS thread? 
There's a lot of good information here.
Between this thread and the one on HawthorneAudio, you folks are close to making me replace a perfectly good P.E. plate amp. 

Again, good information, keep it going!

Bob