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Author Topic: Barbecue Bob on JT-30's - by Rick Beall 4/11/2003  (Read 5713 times)

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Barbecue Bob on JT-30's - by Rick Beall 4/11/2003
« on: February 19, 2012, 12:59:13 AM »
The article below was written in 2003.   Barbecue Bob can be found at

http://www.facebook.com/barbequebobmaglinte

Barbecue Bob on JT-30's - Rick Beall 4/11/03
You could spend a lot of money experimenting with mics, but luckily we have the best harmonica player in Massachusetts Barbecue Bob Maglinte, to give us pointers. Barbecue Bob has toured with Jimmy Rogers, Luther Guitar Junior Johnson, Louisiana Red, his harp was used in the movie Fried Green Tomatoes, and he has been in some very popular bands in Massachusetts.

I think most people would agree that Barbecue Bob is one of the most friendly, knowledgeable, and helpful guys in the harmonica community in the United State. You can visit his website at www.barbequebob.com or email questions directly to him at barbequebob@barbequebob.com

Yes sir! Barbecue Bob was originally "hipped" to JT-30s by none other that Big Walter. And now Barbecue Bob can "hip" you!

We'll start off by saying a lot of mics can work for harp, but studying the two classic ones can help you branch into the other mics, because it gives you a reference point.
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Barbecue Bob with Jimmy Rogers in 1994

For Harp players, the two classic mics are the Astatic JT-30 and the Shure "Green Bullet" model 520 (GB). Barbecue Bob says that for those who play with an extremely light touch, GBs are probably better, but for those with a heavier touch, JT-30's seem the better way to go. This article summarizes an
email conversation I had with Barbecue Bob. Barbacue Bob even did a little research for us.

Barbecue Bob says that, if anything, the JT-30 has a WIDER range than the Green Bullet (GB), be it Controlled Reluctance (CR), Controlled Magnetic (CM), or dynamic. In fact, if you check it out carefully, you'll find that JT-30's have a frequency response of 30-10,000hz, wheras GB's, especially CR's & CM's are 100-10,000hz. The most noticeable difference is you check the response curve charts is that the GB's have a much more exaggerated midrange presence rise than the JT-30's (with the CM's are REALLY exaggerated IMHO). I've found that the exaggerated response is a better match for black faced Fender amps, but sheer overkill on tweed Fenders, and just the opposite with JT-30's. Also, with the GB's, because the bottom end response is weaker than with JT-30's, the bass setting with GB's has to be higher to compensate. GB's get dirtier faster, and for players who play with a light, melodic touch, such as Jazz or Country Harp players, who want some blusier dirt (lighter touch guys depend more on speed than a traditional blues player), then GB's make sense. Tradtional blues players as a general rule, have a considerably heavier touch and often find the JT-30's gives them greater overall control (the master of this was Big Walter Horton, who I saw many times over the years). GB's will growl no matter how soft or hard you play.

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Barbecue Bob with Louisiana Red at HOB in 1994

Barbecue Bob, a heavy blues player himself, says that "I find the JT-30 allows me more flexibility than GB's, and for straight PA use prior to the 70's, JT-30's were in wider use because when NOT cupped, the overall sound was cleaner, but the exaggerated midrange presence rise of the GB's made them a perfect mic for taxicab dispatching for a number of years."

He further says that he just recently won a JT-30 on Ebay for $41, but that "when I opened it, unbeknownst to the seller, instead of finding either a MC151, MC101, MC 127, or MC126, there was 1949 Shure Controlled Reluctance magnetic (CR) cartidge in it, and so I ABCD tested it with JT-30 crystal and ceramics and my Controlled Magnetic (CM) Green Bullet, the CR is SMOOTHER than CM's, but still isn't as smooth as either JT-30 crystals or ceramics."

Harp players like the Astatic JT-30 for heavy Chicago blues, but, unfortunately buying a good one for harp isn't as easy as picking the right model number. The part of the mic which gives it most of its tone is the element and the JT-30 elements, especially the crystal ones, are inconsistent and fragile.

Yet people, including Barbecue Bob, swear by them.

There are four types of elements for the JT-30: two are salt and two are ceramic. The Rochelle salt crystal MC-151 and the ceramic element MC-127 both have a midrange presence rise. The Rochelle salt crystal MC-101 and the ceramic element MC-126 both have, as described in some older Astatic catologues, a substantially flatter response characterics in the midrange.

When we asked Barbecue Bob "Is the JT-30 better with or without the midrange presence rise?", he replied: In MOST cases it is better, but there are some amps that already have unusually STRONG midrange to begin with, so the extra mids winds up making things so distorted to the point of overcompression and consequently, you'll lose your dynamic touch, much like the way 99% of master volume circuits on modern amps have a tendency to work. Barbecue Bob cites as an example, using a JT-30 with an MC151 plugged into my 1948 Sears Silvertone amp (which NEVER leaves my house) leaves the harp WAY too distorted (these amps distort on 2, and it's kinda like built in Hound Dog Taylor), but when I used a JT-30 with an MC101 crystal or MC126 ceramic, which has a substantially flatter response, especially in the midrange, the sound is much smoother and rounder. So what does come down to? For each and every amp, there no one total golden rule, because each amp has a different set of circuitry, and PREshaping of its sound from the factory, so the best thing is with whatever you use for a rig, plus the acoustics of the room you're playing in, clearly you gotta experiment
to see what is going to work. BTW, if I remember correctly from reading some old Shure literature, the CM's were originally developed for military communications work, where the strong midrange presence rise was absolutely necessary. The strongest midrange presence rise I can ever recall hearing was the the legendary Astatic D104, which was the Ham Radio standard mic for decades, but for most harp players, these crystals are FAR too hot for most amps.

Barbecue Bob says that the the ceramics have been around since the 1940's, almost as long as the crystals.
The salt crystals are inherently more prone to damage from moisture and banging than the ceramic. Also, because each salt crystal is a natural product, if you had 5 different crystals you would probably get 5 different sounds. The ceramic elements are less prone to this variation because they are a man-made crystal.

But admist all this confusion, which is best for tone?

Barbecue Bob says that tonewise the ceramics are as good as, and sometimes even a little better than the salt element made in the same year. People often say the ceramic is warmer, darker, more midrange, and hotter. Keith Graham (www.JT-30.com) says he can tell the difference between different elements (that darn
inconsistency!) but he cannot tell the difference between a salt and ceramic element. Barbecue Bob says that the ceramics made today are much more consistent than those made in the 1970's. After side by side testing with a variety of elements Barbecue Bob says that he much prefers the crystal and ceramic elements from the 1970's and earlier.

Barbecue Bob also notes that another variation in the JT-30 is that around 1984 Astatic "opened up"
the grill. A former Astatic sales rep informed Barbecue Bob "off the record" that when part of Astatic's internal labor force went on strike in 1984 and stopped making the salt crystals, Astatic still had an abundant supply of ceramic elements. So, without telling the public, they discretely opened up the grills to make the ceramic sound more like salt elements. The old grills have a nylon mesh and a "felt like" material between grill and the element, wheras the new ones have a piece of paper between them. Barbecue Bob's theory is that the paper allows the mid and high frequencies through more easily, making the ceramics sound more like the crystals they were replacing. The unfortunate consequence was that in later years when Astatic found a supplier for the salt elements, the new grill continued to allow in more moisture which is destructive to the elements.

Astatic made a second, even less desireable modification to the JT-30 in 1984. They changed the cord connector to a mini-XLR connector setup. This connector could use only thin, poor quality cords that held up far worse than the screw on connectors it had replaced. This only lasted until 1985/86, when they settled on the present regular XLR setup.

The JT-30 salt crystals are sensitive to body heat and temperature extremes, and if one sweats profusely,
there will be a drop in output volume. With the older style grill, it's a little bit, but with the newer style grille, not only is there a a noticable drop in volume, but if it gets wet enough, the mids flatten out and the extreme highs and lows over dominate, so obviously, the tone will change. However, the same mike, given to someone who hasn't sweated yet will return it to its original sound. The ceramic element is a man-made crystal that is MUCH more resistant to this.The newer styled grill allows in more moisture and salt crystals self-destruct 75% faster. Some people will give you the false tip to put the crystal in the fridge, but this will make the salt crystal brittle, and turn it back into a pile of salt faster.

To reduce the moisture problem in the new Astatics, Barbecue Bob suggests getting at least 3 more of the
grill papers from Astatic, or cut a piece of cardboard in the same shape of the grille, as Rod Piazza once did for a time with his mics. But even this will not completely resolve the moisture and temperature problems.

Barbecue Bob says that the older style grills, have decidely more bottom end to the sound than mics with the newer grills. Barbecue Bob is not real sure why this is, but he ventures to guess that the thinner materials allows more upper mids and highs to come through, thus "drowning out" the lows. Astatic did this to make the ceramic mimic what they considered to be the most important crystal characteristics.


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Barbecue Bob with Jimmy Rogers in 1977

Barbacue Bob says cable does affect tone. He says that "with the newer 3 pin connector setups, I've found that getting a good quality cord is really important, since many times the Hi-Z cables are still basically Lo-Z cables with a Hi-Z 1/4" phone plug end. A REAL Hi-Z cable, like guitar cords, are a minimum of 600 ohms, and low-Z is less than this. "

Barbecue Bob says that because you are connecting a high impedance mic to a high impedance amplifier jack, the higher the impedence of the connecting cord, the better the sound. He prefers using the old style screw on setup, but with the use of the screw on to 1/4" phono jack adapter so you can use a guitar cable. Why? For one thing, the cables with the screw on connectors for most people are very hard to find, but my main reason is that there are a wide variety of very high quality cables available. Over the years, I've found that the guitar cables tend to have a superior overall signal quality than the cables with the screw on connectors. Not only is the fidelity of the better quality cables superior, but they also have a higher output in addition. Does it mean that you need to spend big dough on these cables, like $200 for a 20' Allessandro cable? No, but there are excellent quality cables like Monster Cable, Spectraflex, etc. and a better quality cable will get you better overall results and will also last longer. The higher the output ability of the cable, the more efficent the signal is, requiring less power to get what you need (What would be, for example, volume on 3 with a good cable could be 4-6 with a bad cable).

If you could buy any JT-30, the best might be one with a 1970's or earlier salt or ceramic element (assuming you happened to get a 'good' one.) In terms of durability, a ceramic will have the edge, but the crystals have the classic, nasty sound, but either of these are your best choices. A worthwhile second choice would be buying a new ceramic element in a new JT-30.

Since the JT-30's are so expensive these days, you could try economizing by buying the an Astatic 200 or 241. They both use the same crystals and ceramics as the JT-30. They will give off a somewhat different overall sound because of the different shape of the housing. They are a little more clumsy for harp because the "stick" is attached to the element housing. The one I happened to buy contained an MC-101 element. I have not had a chance to test it.

But what about the Shure Green Bullets? Richard Hunter reports that Dennis Gruenling, who is a heavily jazz influenced player, uses two Controlled Magnetic Shure Green Bullets and one Controlled Reluctance Bullet for live performances. And Dennis has great tone! Unless they are doing maintenance, you can check out Dennis's tone on his web page under CD's and samples. This bears out Barbecue Bob's generalization about which players prefer which mics and why.

Shure Green Bullets come as both high impedance and low impedance. It is easiest to buy the high impedance because you can plug it directly into your guitar amp without a converter. The low impedance mic has a less strong signal and was designed for situations where a long cord was required in a dispatching office.

Shure Green Bullets also come with a variety of elements. Barbecue Bob says the best is the The early (around 1947) controlled reluctance transducer element. The next best is the the controlled magnetic element, and the least desireable are the newer ones with dynamic elements made in Mexico. Barbecue Bob says the controlled reluctance is much smoother than the controlled magnetic, because he believes the midrange presence rise is not so heavily exaggerated.

For a little more information about Green Bullets, visit the "Shure" section of Keith Graham's site
> www.JT-30.com

Do you have any questions about microphones? You can email Barbecue Bob directly at barbequebob@barbequebob.com because he has gratiously offered to do his best to answer them.

I would like to mention that Barbecue Bob is coming out with a CD soon. He sent me a rough version with preliminary mixes and I really like it. He also sent me notes telling me what amp and mic he used on each song. Cool! --That's exactly what you would expect from Barbecue Bob!

Keep your eye open for the CD. I'll post more info here when I get it.
« Last Edit: February 19, 2012, 01:28:22 AM by Rick »

 

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