GAS Attack - again

The lowdown on the Mississippi Sax. Just for Google, this section is about harmonicas.

GAS Attack - again

Postby MakaInOz » Mon Sep 22, 2008 2:22 am

Bloody eBay. It feeds off GAS (Gear Acquisition Syndrome – can be caught by reading gear-related emails so beware).

My name is Maka and I am a gear-aholic. :twisted:

I like different genres. I like different ‘tools’ (or toys). I enjoy playing through my 520DX Green Bullet and through my Eggstatic (Hi-Z, no volume control) and even through a Lo-Z SM58 ‘clean’ into the PA. Different tunes, different times, different tools.

But when you play harp, there’s always that Chicago Blues sound hiding in the back of your mind. The 520DX is good for what it is, but it isn’t an ‘old style’ CM/CR/crystal bullet mic and doesn’t quite deliver that Chicago sound. Now if I could get one of those ‘real McCoy’ mics – an old CM Shure 520, or a crystal Astatic JT-30 or………but the custom mics are beyond my budget and ‘originals’ rarely appear on eBay without the vultures swarming and driving the price through the roof.

The JT-30 was also made under licence by CAD – the only difference is a brass vs chrome grille. Apart from the cosmetics, the JT-30VC was the same as the CAD HM50VC. And a CAD HM50VC came up on eBay in Oz. And it looked purdy. And it called to me. And I got financial clearance from the domestic management. And I won!!

Can’t wait for the new toy to arrive.

I know it won’t make me into Little Walter, but it is a thing of beauty and deserves a home where it will be appreciated (even if the talent to make it work properly is lacking).
:D
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Re: GAS Attack - again

Postby jbone1 » Mon Sep 22, 2008 3:05 am

you know, if you can get hold of a decent crystal or a 99b86 cm element, you can change that gb into a monster. a firm but careful touch with a small soldering iron, and be sure to heat sink!!!but as long as you're getting a whole fresh mic, i hope it does you dirty- as in chicago dirt!

i see crystal elements going cheep but they aren't the fabled mc151. for the price i may have to grab one up just to see. my problem is, getting hold of a shell or two to mess with. i like the working mics i have so i don't want to swap elements in them, i have a crystal custom bullet and a ragged-looking cm shure 707a bullet, both of which see enough action that i want them just how they are. always good to have a backup or 2!

i recently got a bushman torpedo, and i'm debating swapping a "lessr" crystal element into it. don't know if the side vents would be a plus or minus, but that's why they make duck tape isn't it! the torp is a low-z element and plugs into a p.a., but if you have a sound man who doesn't want to waste his time messing with your high-falutin' mic, you may sound like crap. i did at a jam tonight! in and of itself it's not a bad mic but it does need highs dropped, lows bumped, and some effects if not too much reverb is involved. next time i'm taking an sm58 or a 545s. the torp was feeding back bad at first, then my volume got cut to where i could tell it wasn't cutting through the THREE guitars on stage much. since it's a pain dragging the bassman out for just a few songs, i'm not doing that so much lately. that's kind of why i got the torpedo. plus it was such a good deal!

i'll be interested to hear how the mic you're getting stacks up.
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Re: GAS Attack - again

Postby bottleneck » Tue Sep 23, 2008 7:47 am

i think it is good to have variety in harp mics,here's the tip of my iceberg.lately i've been gigging with three jt30's,one with a 151(or101)one with an astatic 127 ceramic,and of course one with a shure CR?CM.that way i can tweek the sound per room.once in a while i'll use a shure crystal or a turner dynamic for a specific applicatin,but usually stick to the 151,127 or CR/CM.of course i use other shells such as ev630's and shure 520's but i am most comfortable with JT30's,especially with the ears ground off.can you have too many harp mics?

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Re: GAS Attack - again

Postby jcayer » Tue Sep 23, 2008 12:47 pm

hmmm GAS attack ?

better read viewtopic.php?f=27&t=8287 :D
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Re: GAS Attack - again

Postby MakaInOz » Wed Sep 24, 2008 3:47 am

The CAD HM50VC arrived overnight registered mail. All other plans for the evening were quickly ditched for the big mic comparison. Got out the Eggstatic and a 5 metre ¼” to ¼” cable, then the 520DX Green Bullet (which is attached to its own cable) and finally an XLR to ¼” cable we use to put the vocal mics (SM58 knock-offs) into an amp. Feel like a kid at Christmas! I decided to give the Eggstatic (as it is the least hot of my Hi-Z mics) a go first to make sure everything is warmed up.

With everything checked out, I plugged in the matt black and brass HM50VC beauty. Zip, nil, zero, nothing. Must be the cable. I’m sure there’s another XLR to ¼” around somewhere. Replace cable. Still nothing. Check with vocal mic – cables OK. Much swearing. I’ve bought a dud. Never should have bought a crystal mic. I hope its just that the crystal’s dead and not some catastrophic internal failure.

The brain slowly engages. Vague memories of reading about someone with a Blues Blaster having cable issues due to differences in hot pins. Blues Blaster = JT-30 = CAD HM50VC. The only XLR connectors I have are on the vocal mics, and I just buy cables (XLR to XLR or XLR to ¼”) from the local music shop and they’ve all worked fine, so I’ve got no experience with hot pin issues.

So I take the HM50VC, the Smokey amp and the XLR to ¼” cable to work to see whether any of the techs can lend a hand. All the techs are out for the day. More swearing! I bit of googling reveals that the JT-30 (great site) does use a hot 3 pin, with 1 pin as the reference. Looking at the insides of the XLR jack, the 1 and 3 pins are wired together on one wire, and the 2 pin is on the other wire. Looks like a hot 2 pin to this amateur! So I bravely grab the side cutters and cut the jack off the mic cable. Then I cut the wire joining the 1 and 3 pin and use a bit of stray wire to join the 1 and 2 pins. Then join one mic cable wire (the hot one that was on 2 pin) to 3 pin and the other wire to the 2 pin. Twist wires together to hold, and separate things as appropriate with sticky tape (this is all happening on my office desk). Carefully push the internals (the outer casing is off for this ‘surgery’) of the XLR jack into the mic and the plug the ¼” end into the Smokey. We have noise!! The volume pot works!! I can get feedback. I’m not brave enough to play harp in the office, so it will have to wait until I get home, tidy up this electrician’s nightmare with some proper soldering and then I can do the big mic comparison. At least I know the mic works now.

Who’s silly idea was it to put a 3 pin jack system on the end of a 2 wire lead? Give ‘em an option and someone will pick the wrong one! Now I’ll have to label the XLR to ¼” cables as either 2 pin hot (for the vocal mics) or 3 pin hot (for the HM50VC). More cables for the collection - just what I need.

Mic review/comparison to follow (eventually)
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Re: GAS Attack - again

Postby jbone1 » Wed Sep 24, 2008 11:27 am

i have never understood that idea either. had a military nos electrovoice with a hot element in it some years ago, which i had to make a cable for. it had the wrong end of an xlr cable built into the mic housing! once i got the wiring straight, that mic was awesome.

note to self- NEVER PAWN YOUR MICS AGAIN!!!
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Re: GAS Attack - again

Postby MakaInOz » Fri Sep 26, 2008 1:58 am

Got to do a quick mic comparison before the Thu night harp group arrived and we got down to some serious practice.

As expected, the Eggstatic is the least hot. Surprisingly, the CAD HM50VC was slightly less hot than the GB 520DX. I could get the HM50 up to volumes that caused feedback to start with the GB. Not a lot in it, but the GB was definitely the hottest. Might be the HM50 looking for 5 M Ohm input instead of the 1 M ohm input on the amp.

Cupping made a significant difference and I need to experiment more with exactly how to position the HM50 (which is a matt black and bronze JT-30) in my hands. Despite being slightly smaller, it seems to have more bumps (the ‘ears’, the volume control and the big XLR jack) than the GB (volume control and cable only). It’s not difficult, but it needs a bit of practice and refining to get the cupping just right.

The tone of the HM50 was different to the GB. I lack the skills to describe it properly – warmer/sweeter perhaps. Still a ‘bluesy’ tone, just different to the GB. The Eggstatic is close to a vocal mic – very clean.

Initial impressions summary:
Hotness: 1. GB, 2. HM50 3: Eggstatic
Tone: = 1 (tie) GB and HM50 (still haven’t decided which I like better) 3. Eggstatic
Ease of Cupping: 1. Eggstatic (tiny by comparison, no volume control) 2. GB (I’m used to it) 3. HM50 (it will improve with familiarity)
Aesthetic appeal: 1. HM50 (its purdy!) 2. Eggstatic (its quirky) 3. GB
Price (USD): Eggstatic ($20, new on eBay), HM50 ($51, second hand on eBay), 520DX ($81, new, on special at Music123)

Test amp: Johnson T25R (modified preamp tubes).
(When Rico play his guitar, he plays with his Johnson. When I play my harp, I play through my Johnson)
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Re: GAS Attack - again

Postby ricochet » Fri Sep 26, 2008 2:21 am

You're just bragging 'cause you can play with your Johnson in your mouth.
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Re: GAS Attack - again

Postby gheumann » Sat Sep 27, 2008 3:53 pm

MakaInOz wrote:Who’s silly idea was it to put a 3 pin jack system on the end of a 2 wire lead? Give ‘em an option and someone will pick the wrong one! Now I’ll have to label the XLR to ¼” cables as either 2 pin hot (for the vocal mics) or 3 pin hot (for the HM50VC). More cables for the collection - just what I need.



I don't know but it is the single biggest source of confusion among my customers. Not only are there 4 discreet circuits in an XLR-wired cable (the shield can be independent of pin 1 and is still electrically connected at both ends) but as you point out it is used in both high- and low-impedance setups. The low impedance setup is standard, and called "balanced" wiring (which means the signal travels completely independently from ground.) But there is no standard for high-Z, which can be wired balanced or unbalanced (the latter being the norm), pin 2 hot, pin 3 hot and sometimes something else.

It gets worse. The cables with XLR on one end and 1/4" at the other allow you to physically attach a low impedance mic (like an Audix Fireball, Bushman Torpedo, Shure SM57 or -58) to a high impedance device (like a typical guitar/harp amp.) The problem with this is that it sort of works. But you won't get the full output from your mic. Moreover if you insert something impedance-sensitive in line, like my low-Z volume control, the volume control is effectively neutered by this setup.

But wait it gets worse still. When I see a device (usually a PA) with a female XLR jack, I think "ahh - guaranteed to be low impedance input." But it ain't so. Turns out some manufacturers skip an additional $.03 and just wire the damn thing in parallel with the high impedance input. Turns out many audio-computer interfaces are like this. Looks like a low-Z input, but isn't. But it IS wired "balanced." And it gets even more confusing with wireless systems. The AKG SO-40 wireless transmitter has been sold in two forms, one that actually is a true low-Z input and one that isn't. The Shure beltpack wireless transmitters, despite having a cord that connects to your vovcal mic, are also high-Z inputs. All of this works for most people most of the time but adding volume controls throws the whole thing into the air.

OK, I guess that's my problem, not a general one. And it is one of the reasons I can actually compete against high-volume suppliers who can't offer the kind of one-on-one customer support it takes to ensure customers get the right solution for their system. But it just goes to show that XLR connectors can be a source of huge confusion for harp players. There is one genuine advantage to XLR regardless of impedance, and that is the strain relief mechanism in the cable connectors is superior to screw-on or 1/4" connectors. Still, all cables fail, eventually. Carry a spare.

My own rule of thumb is to reserve XLR connectors for my low impedance stuff - typically my vocal and sax mics that get connected to the PA. I use screw-on connectors for all my high-Z stuff because they are the smallest, shortest, lightest and (the male side is) extremely reliable.

End Rant!
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Re: GAS Attack - again

Postby barbequebob » Sun Sep 28, 2008 9:05 pm

I agree 100% when it comes to those XLR to 1/4" cables, and it's really easy to get stuck with a bad cable. Generally anything over 600ohms is considered high z, but there's more to it, and when they changed the JT30's to that XLR-1/4 setup, it definitely comprimised the sound, plus the pot value was the wrong value for crystals and ceramics, as these pots are commonly used in a guitar, and they are more inline with the correct true impedance of a CM/CR GB mike, and for crystals/ceramics, tht pot has to be a minimum of 1meg or higher, preferably 5meg.
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Re: GAS Attack - again

Postby bottleneck » Thu Oct 02, 2008 3:42 am

keep in mind that if you do have a favored mic with an xlr connector you could contact greg at http://www.blowsmeaway.com and have it converted to screw on.

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