East Coast Sound Modulator Circuit?

[BrianBurnsSWL]

Hello again Carl,

Djibouti? Whereizzat?

The way the feds are regulating what comes in to the country in the way of exotic woods, I'm restricting my wood purchases to full time wood suppliers who can run interference for me. Our tax dollars at work, you know. Political Correctness is the new puritanism.

Cheers,

Brian

[KM1H]

The Horn Of Africa, just above the pleasure world of Somalia. A Google will give you lots of info.

Apparently the USN has established a base there to combat the pirates and since Brian is in the USAF he hasnt much of an idea what he will be doing

Knowing him it will be to learn new guitar styles, sample the local brews and take lots of photos and movies.

[WBear2GCR]

Brian,

Are you within traveling distance to any decent hamfests out there??

Get thee to a hamfest!
Chances are you can find "stuff" that will work for your build.
Put a "Wanted" ad up here too, once you ID the few items that you just can't find.

Also scour ur Craigslist for radio stuff... things come up.
Contact whatever your most local ham radio club is and let it be known what you are trying to do... you might get cheap project chassis that are unfinished, and/or parts, and/or freebies too...

Also, you might be able to trade a guitar or guitar work for some of the above?? I'd put an ad into the various online sites, AND maybe even QST about that? Just an idea.

Steve's point on the softrock, is great advice. It turns a so-so receiver into a state of the art unit almost instantly.

Btw, have you got your license yet?

The other question is, have you ever built anything with tubes and high voltage before? IF the answer is no, I would counsel you to NOT start with a rig like you are contemplating at all, quite frankly it is dangerous. Building it mechanically isn't, but making it work is. One needs to get familiar with the techniques and the dangers. Even then ask, you will hear some scary stories from people who are pretty much expert with this right here.

I'd suggest starting out with a built rig. Something like a DX-100, Apache, Johnson Valiant. (there are others as well) These are 100+ watt carrier rigs that can be modified with external modulation via a power amp and transformer OR internal mods to the modulator. This will get ur feet wet, and while it is still dangerous at ~800+ vdc, it is a bit less so than the very HV in a big rig.

You will be heard ok at this power level.

You can always resell that rig, and still work on acquiring the parts for your big rig, and fabricating that as you go along.

Doing some basic mods to the smaller rig will get you familiar with all sorts of issues and techniques, hands-on.

I'd be very cautious about jumping in the deep end of the pool straight away without any prior experience and without much practical knowledge.

Various AM rigs are often found at most hamfests.
Sometimes the price asked is a little high - so what? A few extra bux and a rig in hand, sounds like a plan to me. There are also quite a few rigs and chassis that come up on ebay, and you have to pay the shipping - so what? Even a rig that you don't really want, but has all the raw parts for the rig you want to build is a darn good idea.

Speaking of which, I don't know how far you want to travel to pick something up, but there have been some very very nice big rigs sold out of the west coast that I have seen on ebay, and they have gone pretty cheap. Best bet there.

Even broadcast transmitters...

                  _-_-bear

[BrianBurnsSWL]

Hello Bear,

The nearest hamfest would be an over-nighter for me--I'm really out in the sticks!

My guitars are the high-end kind--I can't afford one myself! Also, I'm a lousy guitar repairman--can't even fix my own mistakes!

The AM receiver I've got covered with a Hammarlund HQ-150. That's what has used up my ham budget for the time being. I spend all day running data and messages through the computer--It's those big old dials that appeal (;->)...

I've had lots of experience with HV, and virtually none with solid state low voltage. I was a ham and electronic tech at HP and the Stanford Microwave Lab from1953--1960. Virtually everything ran on HV in those days. I've also built and modified transmitters, and built a double conversion receiver. The 813 rig looks quite straightforward.

Cheers,

Brian

[WBear2GCR]

Ah... ok.

Fwiw, you need advertising.
That and a celebrity guitar player endorsement or two.

Dept of free advice.

You may have to travel... what can I say?

I'd still pick up a smaller plate modulated rig for now, get on the air, and
then build up ur 813 rig over some time...

these are on ebay right now:

http://www.ebay.com/itm/Vintage-Heathkit-Apache-TX-1-HAM-Tube-Radio-Amateur-Transmitter-/120889776544?pt=LH_DefaultDomain_0&hash=item1c259799a0

http://www.ebay.com/itm/EF-Johnson-Viking-Transmitter-VFO-/200734748443?pt=Vintage_Electronics_R2&hash=item2ebcb92f1b

Not necessarily what you are looking for, but this stuff is around...

             _-_-bear

[BrianBurnsSWL]

Hello Bear,

I putter along at building classical and flamenco guitars, and make a modest living at teaching guitar making. I have finally figured out methods, using audio spectrum analysis, to determine ahead of completion what a guitar is going to sound like. This next batch of 6 instruments should be ready for prime time.

I probably should have mentioned earlier that I'm equipped with a Kenwood TS-530S for SSB and CW, thanks to the generosity of Dennis Regan K6ZJU, an old high school buddy. Yeah, I know it's not AM, but it will keep me out of trouble until I can get an AM rig built.

Cheers,

Brian

[Steve - K4HX]

Very cool. Are you tap tuning the guitar tops and using spectrum analysis here or some other vibrational analysis?

[BrianBurnsSWL]

Hello Steve,

I use an audio analysis program called Spectra Plus. It's a remarkably good program with many features such as an audio signal generator with sweep functions, fast Fourier transform for analyzing an audio spectrum etc. etc.

I use it at several stages in the building process to do everything from measuring the Q of my woods to determining how thick to make tops and backs, and where the main soundbox resonances are located in the audio spectrum so that I can move them around if necessary.

Voicing a guitar is remarkably similar to getting an antenna to load on all the HF bands!

If you are interested, I have a bunch of .pdf's on the voicing process. They are a bit sketchy as they are intended to be notes for my students, rather than a how-to guide. If you have a large in-box, I can email them to you (or anyone else) as attachments. The files are full of photos and are rather large.

Here is a link to a youtube video of me demonstrating the differences between a classical and a flamenco guitar:

http://www.youtube.com/watch?v=kLzSYXlLBnI

and my website:

www.lessonsinlutherie.com

Cheers,

Brian



 

[Steve - K4HX]

Great stuff. That's a beautiful redwood top on the first guitar.

I'm not looking for a how-to guide since I won't be building a guitar any time soon (it's something I'd like to try sometime before I crap out). I have an interest in how acoustic guitars are built, how different sounds are achieved through bracing, wood selection, etc.  Since the 1980's I have thought (not in any great depth) about how spectrum analysis and vibroacoustic instrumentation could be used to "better" or more quickly voice guitars and bring some more science to the art. I think this has happened over the years with some luthiers and manufacturers.

I don't follow this stuff nearly as closely as I did years ago, so maybe this has been done but I always thought it would be neat to do a full up modal analysis using non-contact imaging laser vibrometry of the tops (and probably sides and backs) of widely recognized great sounding guitars. This info could then be used to produce similar sounding guitars. I'm sure I'm over simplifying the process and the follow on production but I'm sure quite a bit would be learned in any event.

Thanks for sharing. You can send the PDFs to my email. I don't think my inbox will choke. 

[Opcom]

Hi Brian,

It looks like you are developing intellectual property, trade secrets, coveted guild knowledge, etc.. and you are doing this for an income.

Why not scheme towards becoming known as the uber guru, the high master, of that stuff? All you would need is a few prominent guitarists to say you are 'the' magic wizard, and your income could increase accordingly. I'm not advocating greed, only getting what your reputation is capable of. In every line, there is one or two people that have become recognized as the best. Take a shot!, well, it's not a shot, its toil, but why shouldn't you have that reputation in your field? Otherwise some upstart will learn from all your free stuff and a few classes and do an end run to glory based on what you have worked on for years.  If that's how it is.

Just saying..

[BrianBurnsSWL]

"It looks like you are developing intellectual property, trade secrets, coveted guild knowledge, etc.. and you are doing this for an income."

Nah, there are a lot of guys doing this sort of thing, and we even have a Yahoo group: leftbrainluthiers@yahoo.com. I'm a moderate sized fish in this little pond, and quite content to swim along in it.

Someday I will gather up all this info, and publish it in one way or another. I'm going to call it "An Incomplete Guide to Classical and Flamenco Guitar Building".

And, as if I didn't have enough to keep me busy, I had to go and let a couple of old high school buddies talk me into getting involved in ham radio again! Talk about a time sink...

Cheers,

Brian

[BrianBurnsSWL]

Hi Steve,

"...I always thought it would be neat to do a full up modal analysis using non-contact imaging laser vibrometry of the tops (and probably sides and backs)..."

That would be wonderful, and I would be doing it, if the equipment were anything like reasonably affordable. The cheapest laser holography set-up is about $50K, and the laser vibrometry rig runs about $100K.

It turns out that building to a fairly traditional design, and getting the lower order resonances in the right spots in the spectrum can be done with pretty low tech methods. If you do that, you're most of the way home.

The big variable, and it's huge, is the wood itself. I do a lot of stiffness, density and Q measurements on tops, backs, and bridges, and the range can be a factor of 3 to 5 for these values! A paper on wood testing will be one of the .pdf's.

"...I won't be building a guitar any time soon (it's something I'd like to try sometime before I crap out)..."

Well, come on out, and build one with me before I crap out! I just teach one on one, and it's a lot of fun for me as well as the student.

BTW, I've taught a lot of classes over the years, and once I tried teaching one student at a time, I never looked back. I'm always trying to get people to hang out a shingle (website) and teach what they know, whether it's Chinese brush painting, or plumbing. Very satisfying...

Cheers,

Brian