Silver Flute project decided....

[Wolf]

I have an original pair of Dayton PT2-A on hand, which are the same as the Silver Flute YAG-20 unit. I *think* I can mate these to the W17RC38-S-4 drivers I won at Iowa. We shall see.... (If not that, I would like to use the little XT25-Neo.) At any rate, it'll have to be minimum 12dB, so we'll see. I might toy with a 3rd order series if I can get it to look nice, but I'll start with a parallel xover. I know planar/ribbon drivers are prone to damage with lower order/SXO topologies, but I might just have to try it and see. I've had these for a while now. If I smoke 'em, I smoke 'em. =-) I don't want to attempt a 3-way in this case.
Later,
Wolf

[neildavis]

> I have an original pair of Dayton PT2-A on
> hand

Odd coincidence...I took one of mine apart the night before. No date on it, but it is one of the originals.

I've played with the HIVI version (R2T) of these before using a very steep (8-pole) active crossover. I had an A/B switch setup to quickly go back and forth between the R2T's and a pair of 2" Heil drivers with a 5" Excel woofer. Both the R2T and the Heil have a neutral, uncolored sound that is very similar, except the R2T sounded like it had a distortion booster circuit in line. Very noticeable--not a subtle difference. When I switched back and forth it was the same uncolored ribbon-like sound, but "distortion booster on" or "distortion booster off". Oddly enough, for some music sources the distortion wasn't all that objectionable (mostly even harmonics?), but with A/B testing, at loud volumes and with an 8-pole 2300Hz crossover it was easy to isolate.

If you take apart a planer like the PT2 and look at how the magnet structure is built, it should be fairly obvious why these tweeters have trouble at high output, where there is a lot of diaphragm excursion. The magnet structure in a planar is not symmetrical and not linear, so as the diaphragm moves it cuts a different number of flux lines. Easier to show in a diagram, but bottom line is that most planars are doomed to have high distortion at high output at low frequencies, where this is a lot of diaphragm movement.

OK, so why did I take it apart? I got a bug up my **** to make a planar in the shape of a ring. Imagine the diaphragm in "normal" vertical position, then rotate it 90 degrees to the right. Then wrap it around a 1" pipe that is vertical. This would result in a planar with fairly good vertical dispersion (about 1" tall) and excellent horizontal dispersion (360 degree radiation pattern).

It wouldn't be that hard to make a ring-shaped magnet structure, by cutting the right size steel tubing. However, assembly would be difficult because of the way the magnets attract and repel. Also, you would need to run FEMM or a comparable field simulator to make sure the field on the outside of the ring was balanced with the field on the inside--or that it was fairly close, and size the magnets accordingly.

The plan was to play with the PT2 diaphragms for a prototype and then use my RT2's for the final, since the HiVi and newer PT2B/C models use the aluminum conductors and a lighter weight kapton backing rather than the Cupric conductors and heavy kapton backing that was used in the original models. But after taking the thing apart I'm inclined to think that the ring-shaped planar isn't worth it (there are a number of reasons), although for some stubborn reason I still keep thinking about it.

[mike1234]

Interesting... I've considered making something similar on a lager scale but I hadn't thought of using existing planar parts to do it. Hmmm... I wonder how the larger Hi-Vi RT8 would do?? What I haven't found are disc or ring magnets with radial patterns... or if they're even made. Otherwise several narrow rectangular magnets must be mounted in a ring pattern on a vertical tube, right?

> Odd coincidence...I took one of mine apart
> the night before. No date on it, but it is
> one of the originals.

> I've played with the HIVI version (R2T) of
> these before using a very steep (8-pole)
> active crossover. I had an A/B switch setup
> to quickly go back and forth between the
> R2T's and a pair of 2" Heil drivers
> with a 5" Excel woofer. Both the R2T
> and the Heil have a neutral, uncolored sound
> that is very similar, except the R2T sounded
> like it had a distortion booster circuit in
> line. Very noticeable--not a subtle
> difference. When I switched back and forth
> it was the same uncolored ribbon-like sound,
> but "distortion booster on" or
> "distortion booster off". Oddly
> enough, for some music sources the
> distortion wasn't all that objectionable
> (mostly even harmonics?), but with A/B
> testing, at loud volumes and with an 8-pole
> 2300Hz crossover it was easy to isolate.

> If you take apart a planer like the PT2 and
> look at how the magnet structure is built,
> it should be fairly obvious why these
> tweeters have trouble at high output, where
> there is a lot of diaphragm excursion. The
> magnet structure in a planar is not
> symmetrical and not linear, so as the
> diaphragm moves it cuts a different number
> of flux lines. Easier to show in a diagram,
> but bottom line is that most planars are
> doomed to have high distortion at high
> output at low frequencies, where this is a
> lot of diaphragm movement.

> OK, so why did I take it apart? I got a bug
> up my **** to make a planar in the shape of
> a ring. Imagine the diaphragm in
> "normal" vertical position, then
> rotate it 90 degrees to the right. Then wrap
> it around a 1" pipe that is vertical.
> This would result in a planar with fairly
> good vertical dispersion (about 1"
> tall) and excellent horizontal dispersion
> (360 degree radiation pattern).

> It wouldn't be that hard to make a
> ring-shaped magnet structure, by cutting the
> right size steel tubing. However, assembly
> would be difficult because of the way the
> magnets attract and repel. Also, you would
> need to run FEMM or a comparable field
> simulator to make sure the field on the
> outside of the ring was balanced with the
> field on the inside--or that it was fairly
> close, and size the magnets accordingly.

> The plan was to play with the PT2 diaphragms
> for a prototype and then use my RT2's for
> the final, since the HiVi and newer PT2B/C
> models use the aluminum conductors and a
> lighter weight kapton backing rather than
> the Cupric conductors and heavy kapton
> backing that was used in the original
> models. But after taking the thing apart I'm
> inclined to think that the ring-shaped
> planar isn't worth it (there are a number of
> reasons), although for some stubborn reason
> I still keep thinking about it.

[Wolf]

> Odd coincidence...I took one of mine apart
> the night before. No date on it, but it is
> one of the originals.

> I've played with the HIVI version (R2T) of
> these before using a very steep (8-pole)
> active crossover. I had an A/B switch setup
> to quickly go back and forth between the
> R2T's and a pair of 2" Heil drivers
> with a 5" Excel woofer. Both the R2T
> and the Heil have a neutral, uncolored sound
> that is very similar, except the R2T sounded
> like it had a distortion booster circuit in
> line. Very noticeable--not a subtle
> difference. When I switched back and forth
> it was the same uncolored ribbon-like sound,
> but "distortion booster on" or
> "distortion booster off". Oddly
> enough, for some music sources the
> distortion wasn't all that objectionable
> (mostly even harmonics?), but with A/B
> testing, at loud volumes and with an 8-pole
> 2300Hz crossover it was easy to isolate.

> If you take apart a planer like the PT2 and
> look at how the magnet structure is built,
> it should be fairly obvious why these
> tweeters have trouble at high output, where
> there is a lot of diaphragm excursion. The
> magnet structure in a planar is not
> symmetrical and not linear, so as the
> diaphragm moves it cuts a different number
> of flux lines. Easier to show in a diagram,
> but bottom line is that most planars are
> doomed to have high distortion at high
> output at low frequencies, where this is a
> lot of diaphragm movement.

> OK, so why did I take it apart? I got a bug
> up my **** to make a planar in the shape of
> a ring. Imagine the diaphragm in
> "normal" vertical position, then
> rotate it 90 degrees to the right. Then wrap
> it around a 1" pipe that is vertical.
> This would result in a planar with fairly
> good vertical dispersion (about 1"
> tall) and excellent horizontal dispersion
> (360 degree radiation pattern).

> It wouldn't be that hard to make a
> ring-shaped magnet structure, by cutting the
> right size steel tubing. However, assembly
> would be difficult because of the way the
> magnets attract and repel. Also, you would
> need to run FEMM or a comparable field
> simulator to make sure the field on the
> outside of the ring was balanced with the
> field on the inside--or that it was fairly
> close, and size the magnets accordingly.

> The plan was to play with the PT2 diaphragms
> for a prototype and then use my RT2's for
> the final, since the HiVi and newer PT2B/C
> models use the aluminum conductors and a
> lighter weight kapton backing rather than
> the Cupric conductors and heavy kapton
> backing that was used in the original
> models. But after taking the thing apart I'm
> inclined to think that the ring-shaped
> planar isn't worth it (there are a number of
> reasons), although for some stubborn reason
> I still keep thinking about it.

I'll shoot for 3k, but slope will start as a 12dB, and maybe go third order.
Later,
Woolf(heh)

[neildavis]

Provided Link: Roger Russell Polygon speaker


> Otherwise several narrow rectangular magnets
> must be mounted in a ring pattern on a
> vertical tube, right?

No--for a planar it's a lot easier than that, but I'd have to draw a picture to make it clear, and I won't be able to get to that until this weekend. The current would be flowing in a path around the ring, and the movement of the diaphragm would be in and out. Using the three finger rule, the magnetic field would need to be "up and down", which could be done with a pair of disc magnets on the inside of the ring and some small block magnets on the outside of the ring. I haven't fully thought it out or made any diagrams, but I'm fairly sure that it will work.

But there two questions here: can you build a ring-shaped ribbon speaker, and *should* you build a ring-shaped speaker. My plan was to tackle the second question first, using an array of dynamic drivers in a ring shape. Roger Russell described some ring speaker experiments in the link, but I don't think he went far enough. Enough said...

[Pete Schumacher ®]

> No--for a planar it's a lot easier than
> that, but I'd have to draw a picture to make
> it clear, and I won't be able to get to that
> until this weekend. The current would be
> flowing in a path around the ring, and the
> movement of the diaphragm would be in and
> out. Using the three finger rule, the
> magnetic field would need to be "up and
> down", which could be done with a pair
> of disc magnets on the inside of the ring
> and some small block magnets on the outside
> of the ring. I haven't fully thought it out
> or made any diagrams, but I'm fairly sure
> that it will work.

> But there two questions here: can you build
> a ring-shaped ribbon speaker, and *should*
> you build a ring-shaped speaker. My plan was
> to tackle the second question first, using
> an array of dynamic drivers in a ring shape.
> Roger Russell described some ring speaker
> experiments in the link, but I don't think
> he went far enough. Enough said...

How are you going to get a continuous kapton or other membrane to move in and out, expanding and contracting the diameter of the ring? Those membranes usually have very little elasticity associated with them.

[mike1234]

I don't think a ring of multiple drivers will behave the same as a singular tube-shaped driver. From what I've read, this causes comb filtering issues.

I would try using only an inner magnet at first. That would leave the exterior radiating surface unfettered.

I suspect this design would be extremely inefficient due to increased resistence to movement inherent in the design. I suppose one could fabricate a spring out of flexible cloth running longitudinally at the back of the tube. Of course there would be a dead spot where the spring is and inequities of the contraption's suspensiom would likely cause it to behave more like a bending wave driver, I suspect. How would one keep the spacing correct... rubber bands sandwiched between the magnet and the radiator positioned at top and bottom of the magnet? Maybe thin strips of tape woold work better... more tweakable?

> No--for a planar it's a lot easier than
> that, but I'd have to draw a picture to make
> it clear, and I won't be able to get to that
> until this weekend. The current would be
> flowing in a path around the ring, and the
> movement of the diaphragm would be in and
> out. Using the three finger rule, the
> magnetic field would need to be "up and
> down", which could be done with a pair
> of disc magnets on the inside of the ring
> and some small block magnets on the outside
> of the ring. I haven't fully thought it out
> or made any diagrams, but I'm fairly sure
> that it will work.

> But there two questions here: can you build
> a ring-shaped ribbon speaker, and *should*
> you build a ring-shaped speaker. My plan was
> to tackle the second question first, using
> an array of dynamic drivers in a ring shape.
> Roger Russell described some ring speaker
> experiments in the link, but I don't think
> he went far enough. Enough said...

[neildavis]

It's really the same problem you have in a straight planar. There isn't a suspension, and the diaphragm is clamped to the frame on the top and sides. The diaphragm just bulges in the middle between the two sets of traces, and there is enough elasticity in the backing material to accommodate that motion. That movement might be constrained somewhat if you bend the diaphragm around a tight radius, but I don't know by how much. And I probably won't do any testing to find out, although I still think it might be fun to play with.

A true ribbon design in the shape of a ring would work better. The texturing that is usually put in the ribbon should provide enough relief to allow for the "changing diameter" as the diaphragm moves in and out.

Or maybe not. There is actually a very good solution that will work better than either of these approaches, but I'm not ready to discuss it publicly. Also, I want to try a dynamic version of the ring shape first.

One of the problems with using ring drivers that might not be obvious is that you need to delay the midrange ring array to align with the tweeter array. If the tweeter array is made up of small drivers like the ND16 and the mid is a 2" driver, the acoustic centers are fairly far off--probably more than what you want to deal with in a passive crossover. So this project might take a while...

I just ordered 16 of the new old stock MT14 drivers for the woofer ring. So this experiment would look like a wedding cake with a ring of 5" drivers at the bottom, 2" drivers in the middle tier and the ND16's at the top. Should look pretty cool with those sloping walls, eh?

[Pete Schumacher ®]

> It's really the same problem you have in a
> straight planar. There isn't a suspension,
> and the diaphragm is clamped to the frame on
> the top and sides. The diaphragm just bulges
> in the middle between the two sets of
> traces, and there is enough elasticity in
> the backing material to accommodate that
> motion. That movement might be constrained
> somewhat if you bend the diaphragm around a
> tight radius, but I don't know by how much.
> And I probably won't do any testing to find
> out, although I still think it might be fun
> to play with.

> A true ribbon design in the shape of a ring
> would work better. The texturing that is
> usually put in the ribbon should provide
> enough relief to allow for the
> "changing diameter" as the
> diaphragm moves in and out.

> Or maybe not. There is actually a very good
> solution that will work better than either
> of these approaches, but I'm not ready to
> discuss it publicly. Also, I want to try a
> dynamic version of the ring shape first.

> One of the problems with using ring drivers
> that might not be obvious is that you need
> to delay the midrange ring array to align
> with the tweeter array. If the tweeter array
> is made up of small drivers like the ND16
> and the mid is a 2" driver, the
> acoustic centers are fairly far
> off--probably more than what you want to
> deal with in a passive crossover. So this
> project might take a while...

> I just ordered 16 of the new old stock MT14
> drivers for the woofer ring. So this
> experiment would look like a wedding cake
> with a ring of 5" drivers at the
> bottom, 2" drivers in the middle tier
> and the ND16's at the top. Should look
> pretty cool with those sloping walls, eh?

When I worked on the US Fleet's Mark2 - Mod1 Sonar Countermeasure, we accomplished omnidirectional jamming by using a set of Ring radiators for a series of ultrasonic frequency bands. (The SPL output was unreal!!).

I wonder what a well designed piezo ring would do from a linearity standpoint?

[neildavis]

Provided Link: HiVi UR2


> I wonder what a well designed piezo ring
> would do from a linearity standpoint?

Arrays help reduce distortion, and there may be other benefits than just higher SPL. However, the line array gets away from a point source and replaces it with a line source, and I'd like to experiment with a point source array, where the size of the array is still less than the highest wavelength for each part of the array. The ring shape is probably the best configuration for this experiment, and for practical reasons it will be an octagonal ring. The graphic shows that an array of 8 2" drivers will be about 3" tall and 6" in "diameter".

To make this omnidirectional with no comb filtering, the 2" array will need to get crossed over to the tweeter array at approximately 4K, probably with fairly steep slopes and digital delay.

Besides just wanting to experiment with this, my son is starting woodshop classes at Woodcraft, so this should be a good project for us to work on. And I will probably end up doing something totally tacky like using those HiVi 2" transparent surround drivers (see the link) with lights inside the box. I already ordered some high power 3W tricolor LED's--just need some code to make them flash to the music.

[boso]

> When I worked on the US Fleet's Mark2 - Mod1
> Sonar Countermeasure, we accomplished
> omnidirectional jamming by using a set of
> Ring radiators for a series of ultrasonic
> frequency bands. (The SPL output was
> unreal!!).

> I wonder what a well designed piezo ring
> would do from a linearity standpoint?

I used to work here,
<A HREF="http://www.npt.nuwc.navy.mil/autec/">http://www.npt.nuwc.navy.mil/autec/</A>
Ever been there?

[Pete Schumacher ®]

> I used to work here,
> <A HREF="http://www.npt.nuwc.navy.mil/autec/">http://www.npt.nuwc.navy.mil/autec/</A> Ever
> been there?

I did all the design and testing, he got to take it to sea.

When the MK2 finally went to testing, it lasted longer, played louder, and was far more random than anyone expected. It was SO satisfying to overcome the problems and produce something far more capable than anyone expected.

Singer had originally been given a million dollars to conclude that the original MK2 transducer array just couldn't produce the Navy's new sound profile, what we called the "buy-line". No point on the output response could be below the buy-line except in the stop band of course, where nothing could be above the buy-line.

The problem is, anything above the buy-line is wasted power, not that too loud is bad, but that it uses excess power and shortens battery life. Singer just couldn't figure out how to get the SPL levels out of the rings, noise over a wide range of frequencies, in order to jam sonar. I figured out early on that you couldn't use a standard source for noise, like a noise diode, and still attain the high efficiency needed to deliver sound power to the water. It was really satisfying to get around the problems no one else could solve. My engineer partner Jim was a whiz at machine code and programming the microcontroller to execute the signal generation scheme. I designed the power amp that shifted from Class D to Class AB depending on signal requirements. With the ocean as a heat sink, we were getting over 30W per cubic inch from our amplifier space. This thing kicked major ****!!!

Then, my boss takes it to the Navy for testing, gets to go on the boats or subs, always leaving the two guys who created the thing behind. Sucked to say the least. But that was a really satisfying project to work on. 6 years total, off and on.

During that time, I visited Hazeltine in Boston, since Emerson Electric had just assimilated them into the collective. They were big into sonar and countermeasures, just BIGGER in terms of power and size. Our device was 3" diameter and maybe 3 feet long. Hazeltine was making these 6" diameter 12' long torpedo looking things. They had these huge hunks of piezo material inserted into a machined piece of aluminum that they deformed under pressure to insert the piezo in a gap. The pressure was released and the piezo was then under a very large bias pressure. Now, if you applied the signal to the piezo, it would cause the entire piece of machined aluminum to vibrate, and a more horrendous squall you've never heard. Even without the sea pressure to really load the device properly, the output was deafening at very low power levels. We went there to "learn" from their experience.

As I'm walking through the lab, I talk to their version of me and get him to describe what he's doing, the problems he's working on and how close they are to finishing. As he relates his efforts, I begin to realize that he's exactly where we were two or three years before, will run into exactly the same problems, and will realize that they have to do something different or they'll never get the required efficiency. I tried to let them know, but, who the heck are we? We're just working on these soda straws while they have fire hoses!!

A couple years later, after I transfered back to St. Louis, I got a call from the lab director and head engineer and they wanted to meet me, pick my brain, to find out what magic we pulled to get our device to work. They sat across the table from me and asked question after question, writing down whatever they could. I was stunned. But every question they asked had a textbook answer. "How did you design the pot-core inductors and transformers?" "I followed the recommended design process that accompanies the ferrite manual," I replied. The look on their faces was just priceless. I was giving them nothing they were hoping for.

Finally, finally, he asks me for my thoughts on why they were having the overheating problems, the poor efficiency, short battery life . . . and I told them the truth, what I told them in the meeting two years before, "you can't do it that way, you have to generate your signal differently." It sucks to start over, but when you do, the rest of it becomes easy, if you learn from what you did wrong the first time.

Man, that was a fun project . . .

[boso]

> I did all the design and testing, he got to
> take it to sea.

> When the MK2 finally went to testing, it
> lasted longer, played louder, and was far
> more random than anyone expected. It was SO
> satisfying to overcome the problems and
> produce something far more capable than
> anyone expected.

> Singer had originally been given a million
> dollars to conclude that the original MK2
> transducer array just couldn't produce the
> Navy's new sound profile, what we called the
> "buy-line". No point on the output
> response could be below the buy-line except
> in the stop band of course, where nothing
> could be above the buy-line.

> The problem is, anything above the buy-line
> is wasted power, not that too loud is bad,
> but that it uses excess power and shortens
> battery life. Singer just couldn't figure
> out how to get the SPL levels out of the
> rings, noise over a wide range of
> frequencies, in order to jam sonar. I
> figured out early on that you couldn't use a
> standard source for noise, like a noise
> diode, and still attain the high efficiency
> needed to deliver sound power to the water.
> It was really satisfying to get around the
> problems no one else could solve. My
> engineer partner Jim was a whiz at machine
> code and programming the microcontroller to
> execute the signal generation scheme. I
> designed the power amp that shifted from
> Class D to Class AB depending on signal
> requirements. With the ocean as a heat sink,
> we were getting over 30W per cubic inch from
> our amplifier space. This thing kicked major
> ****!!!

> Then, my boss takes it to the Navy for
> testing, gets to go on the boats or subs,
> always leaving the two guys who created the
> thing behind. Sucked to say the least. But
> that was a really satisfying project to work
> on. 6 years total, off and on.

> During that time, I visited Hazeltine in
> Boston, since Emerson Electric had just
> assimilated them into the collective. They
> were big into sonar and countermeasures,
> just BIGGER in terms of power and size. Our
> device was 3" diameter and maybe 3 feet
> long. Hazeltine was making these 6"
> diameter 12' long torpedo looking things.
> They had these huge hunks of piezo material
> inserted into a machined piece of aluminum
> that they deformed under pressure to insert
> the piezo in a gap. The pressure was
> released and the piezo was then under a very
> large bias pressure. Now, if you applied the
> signal to the piezo, it would cause the
> entire piece of machined aluminum to
> vibrate, and a more horrendous squall you've
> never heard. Even without the sea pressure
> to really load the device properly, the
> output was deafening at very low power
> levels. We went there to "learn"
> from their experience.

> As I'm walking through the lab, I talk to
> their version of me and get him to describe
> what he's doing, the problems he's working
> on and how close they are to finishing. As
> he relates his efforts, I begin to realize
> that he's exactly where we were two or three
> years before, will run into exactly the same
> problems, and will realize that they have to
> do something different or they'll never get
> the required efficiency. I tried to let them
> know, but, who the heck are we? We're just
> working on these soda straws while they have
> fire hoses!!

> A couple years later, after I transfered
> back to St. Louis, I got a call from the lab
> director and head engineer and they wanted
> to meet me, pick my brain, to find out what
> magic we pulled to get our device to work.
> They sat across the table from me and asked
> question after question, writing down
> whatever they could. I was stunned. But
> every question they asked had a textbook
> answer. "How did you design the
> pot-core inductors and transformers?"
> "I followed the recommended design
> process that accompanies the ferrite
> manual," I replied. The look on their
> faces was just priceless. I was giving them
> nothing they were hoping for.

> Finally, finally, he asks me for my thoughts
> on why they were having the overheating
> problems, the poor efficiency, short battery
> life . . . and I told them the truth, what I
> told them in the meeting two years before,
> "you can't do it that way, you have to
> generate your signal differently." It
> sucks to start over, but when you do, the
> rest of it becomes easy, if you learn from
> what you did wrong the first time.

> Man, that was a fun project . . .

I worked on MK27 and Mk30 mobile targets, basically an electronic torpedo with a sound system to simulate a submarine. They could be tweaked to simulate an exact submarine by mimicking the exact hull resonances of a specific sub. We used HP wave analyzers with 1 Hz resolution to tweak them. The target towed an array of transducers to simulate a sub sized sound source. They were fun to tear down and refurbish and prep for their next assignment.

I also occasionally would sit in at command control the war room and write reports on target performance reports for the weapons shop. This would aid in post run data reduction and mark time for sonobuoy drops. It was neat getting to listen in to all the radio communications between the helos and the fixed wing sub hunters and watch sub commanders chase the targets when they would go into evasive maneuvers and see how good the crew could do at pumping a torpedo at it especially if they were guiding it by wire.

In the end I was in charge of QA for the weapons shop. So if I didn’t sign off on a target prep due to problems and that would hold up a sub for an additional 24 hours and the questioning was intense. Do your job and get fried for it. I wasn’t getting paid for it as that was too many pay grade jumps, but they were sure they could make it up to me later, sure.

I did get one ‘that a boy’ in writing from the director of Navel Underwater Systems as directed by Congress for excellent little observation that I made that saved the day but I cant go into the story.

[cmac]

Hey you guys are giving away all of our secrets. Remember our enemies are delivering weapons on Datsun and Schwinn platforms. :^)

> I worked on MK27 and Mk30 mobile targets,
> basically an electronic torpedo with a sound
> system to simulate a submarine. They could
> be tweaked to simulate an exact submarine by
> mimicking the exact hull resonances of a
> specific sub. We used HP wave analyzers with
> 1 Hz resolution to tweak them. The target
> towed an array of transducers to simulate a
> sub sized sound source. They were fun to
> tear down and refurbish and prep for their
> next assignment.

> I also occasionally would sit in at command
> control the war room and write reports on
> target performance reports for the weapons
> shop. This would aid in post run data
> reduction and mark time for sonobuoy drops.
> It was neat getting to listen in to all the
> radio communications between the helos and
> the fixed wing sub hunters and watch sub
> commanders chase the targets when they would
> go into evasive maneuvers and see how good
> the crew could do at pumping a torpedo at it
> especially if they were guiding it by wire.

> In the end I was in charge of QA for the
> weapons shop. So if I didn’t sign off on a
> target prep due to problems and that would
> hold up a sub for an additional 24 hours and
> the questioning was intense. Do your job and
> get fried for it. I wasn’t getting paid for
> it as that was too many pay grade jumps, but
> they were sure they could make it up to me
> later, sure.

> I did get one ‘that a boy’ in writing from
> the director of Navel Underwater Systems as
> directed by Congress for excellent little
> observation that I made that saved the day
> but I cant go into the story.

[Pete Schumacher ®]

> Hey you guys are giving away all of our
> secrets. Remember our enemies are delivering
> weapons on Datsun and Schwinn platforms. :^)

But, the Chicoms are developing a submarine fleet of their own, as is Iran. Those countermeasures should still work very well, and they need to know that.