Littoral
1352 posts
Jan 25, 2016
3:49 AM
|
I say no, but that's only because of my experience with a Greg's bulletized 57. That mic set-up, to my ears, has a near perfect sweep without effecting tone. I've used it in a lot of applications and I am exceedingly sensitive to anything in the way of tone (which, IMHO and not to spawn the argument again, is 95% the player, all else is gear). My other bullets with VC have always been used as off/on because of the difference in tone.
So...?
|
Littoral
1353 posts
Jan 25, 2016
3:50 AM
|
Dennis Gruenling weighs in:
"If you invest in and use a good vintage mic, it's for the tone of it. A volume control will compromise that, especially with a crystal or ceramic element. If you need one, your best bet is an inline V/C but will still compromise some tone."
|
arnenym
368 posts
Jan 25, 2016
8:13 AM
|
I've done recordings with and without volume control.
Volume controls do affect the tone. On one type of mics more than on another.
|
Goldbrick
1285 posts
Jan 25, 2016
8:49 AM
|
If you are reducing the amount signal hitting the amp-it will change how amp reacts.
How you perceive the result of that change is what needs to satisfy you
|
Littoral
1355 posts
Jan 25, 2016
9:16 AM
|
Goldbrick:"If you are reducing the amount signal hitting the amp-it will change how amp reacts."
Yes, and basic logic gets us there and certainly reflects my experience with most mics and why I use their VC (if they have one) as On/Off.
But not the 57. I get an exceptional response out of all of my amps at low volume with the 57 turned down with the amp still at a high volume. Other mics, no way.
|
MindTheGap
1032 posts
Jan 25, 2016
11:18 AM
|
The DC resistance of a crystal element is effectively infinite, and it's impedance as and AC source is as a result of it's capacitance, so varies with frequency. If you load it with a VC (a DC resistor) then it's to change it's frequency response in unexpected ways. When I started looking at harp mics I couldn't credit that this was what was done - you'd never design a circuit like that if you were after fidelity - but it is and the fact that they sound good I guess is another happy harmonica thing. Just shows how real-world experience can trump theory.
The source impedance of dynamic mics, even after a transformer, is much lower, so you can load them with and it won't affect the frequency response very much. This is called Impedance Bridging.
Last Edited by MindTheGap on Jan 25, 2016 11:22 AM
|
barbequebob
3121 posts
Jan 25, 2016
11:50 AM
|
From my own experience, if the volume controls fully matches the mic's TRUE impedance, it really shouldn't do that at all. Everything over 600 ohms is considered high impedance, but there is some serious variance to that. Crystals and ceramics are of ULTRA high impedance, and so the volume control needs to be 1meg at a minimu, 5meg ideally. The Green Bullet type of mics using CM/CR cartridges are closer to medium impedance and shouldn't have a volume control no higher than 500K impedance and many dynamic mics need to be anywhere from 100K-250K.
----------
Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
|
mlefree
532 posts
Jan 25, 2016
12:09 PM
|
Greg Heumann?
Oh yeah. He's vacationing in Hawaii.
----------
SilverWing Leather - Custom leather creations for musicians and other eccentrics.
|
Littoral
1356 posts
Jan 25, 2016
12:41 PM
|
Replies that remind me why I'm here.
Nice, all.
|
1847
3139 posts
Jan 25, 2016
12:48 PM
|
you are adding resitance, there will be a slight differance in tone.
----------
if you appreciate what you have...
it becomes more.
|
bluemoose
1111 posts
Jan 25, 2016
1:04 PM
|
I did the harp weekend last summer with Carlos and Ron. We A/B'd my mics with and without an in-line volume control against two different amps. Very interesting.
I no longer use an in-line vc.
MBH Webbrain - a GUI guide to Adam's Youtube vids
FerretCat Webbrain - Jason Ricci's vids (by hair colour!)
|
harpwrench
1052 posts
Jan 25, 2016
1:29 PM
|
I have a couple freakish good CMs that sound close to identical without VC's in small shell bullets, but one now resides in a small shell with a VC done right by a pro. Even at wide open there's a difference in response between them now, it's not just a crystal thing. I still carry it along but it only comes out when someone else plays my rig.
----------
www.spiersharmonicas.com
|
SuperBee
3292 posts
Jan 25, 2016
2:46 PM
|
I have a CM I never liked. A 1959 99H86. I liked the shell, very clean 60s foil-label JT. But I never used it because the tone was just kinda high and thin. Recently took the volume pot out and I do believe it's somewhat better. I quite like it now, and I really have never liked it before.
I put a MC151 in another JT shell which has a vc fitted. It was certainly better than the old turner crystal which was previously in that shell, but I was not impressed enough to want to use it. I know all crystals sre not created equal, but shall try it without the pot and see how it is before I give up.
|
528hemi
497 posts
Jan 25, 2016
3:54 PM
|
My experience is it can effect tone but not always in a bad way....depends on the Mic
A hot Mic with a VC makes it very usable if you don't want a very over driven sound and feedback.
Last Edited by 528hemi on Jan 25, 2016 3:56 PM
|
harmonicanick
2352 posts
Jan 25, 2016
4:16 PM
|
My two favourite mics are an 1986 shure green bullet and an Electrovoice, neither have vc's and IMHO you do not need it
|
Greg Heumann
3159 posts
Jan 25, 2016
6:22 PM
|
Said it before I'll say it again. Properly matched volume controls have minimal (but non-zero) impact on tone. The benefits outweigh the drawbacks.
Musselwhite, Ricci, Hummel, Estrin, Piazza, Ford, Smith, Kumar, Westside Andy, many more pros use volume controls. They must not be that bad. I love having a VC.
----------
***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
|
Barley Nectar
1082 posts
Jan 25, 2016
7:37 PM
|
I'm with Greg, the added versatility of a VC is a necessity in my world. I use CM's with a 1M pot. With the pot dimed, it has virtually no effect on the signal...BN
Last Edited by Barley Nectar on Jan 25, 2016 7:41 PM
|
Barley Nectar
1083 posts
Jan 25, 2016
7:42 PM
|
I'm with Greg, the added versatility of a VC is a necessity in my world. I use CM's with a 1M pot. With the pot dimed, it has virtually no effect on the signal...BN
|
1847
3142 posts
Jan 25, 2016
7:45 PM
|
is that the correct value?
----------
if you appreciate what you have...
it becomes more.
|
Barley Nectar
1085 posts
Jan 25, 2016
8:10 PM
|
Who knows, that is just what I use...BN
|
shakeylee
493 posts
Jan 25, 2016
8:17 PM
|
i never use a VC. to each his own.
edit.
oops. i forgot,in one band,for a few years,i used a volume pedal,because there were so many people in the band i couldn't always get to my amp on crowded stages
----------
www.shakeylee.com
Last Edited by shakeylee on Jan 25, 2016 8:19 PM
|
mlefree
536 posts
Jan 25, 2016
9:51 PM
|
For a long time
I didn't understand the fuss
about volume controls.
Then I got one of Greg's.
Michelle
----------
SilverWing Leather - Custom leather creations for musicians and other eccentrics.
|
Harpaholic
796 posts
Jan 25, 2016
10:00 PM
|
I use 100K audio pots with CM's/CR's.
1 meg audio for crystals.
A 1 meg pot will work fine, but it will have less sweep compared to a 100K, IME.
IMO, a VC inside a shell effects tone more so than an inline VC, especially a bullet mic with a CR/CM.
When I started using audio taper pots, I noticed less effect on tone inside a mic and only a slight difference in an inline.
I only use miltary spec pots that measure within 10% of 100K or 1 meg. Most of the cheap pots out there can be as much as 30% out of spec.
Since most of my custom builds these days are for myself or customer's wanting the best, I use the good stuff.
|
Greg Heumann
3161 posts
Jan 26, 2016
11:23 AM
|
I believe the optimal value for CM/CR is 250K. For crystals, 5M when you can get it, 1M when you can't. (5M pots simply don't exist in some of the smaller form factors I use.)
----------
***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
|
bigd
614 posts
Jan 26, 2016
12:24 PM
|
I can't hear any discernible difference in real life (stage situations). If a band plays with versatile dynamics (I play with lots and lots of singers) it is invaluable to have volume control at your finger tips!
----------
Facebook
|
hvyj
2923 posts
Jan 27, 2016
9:20 AM
|
Don't know about bullet mics because I don't use them. I do regularly use 545 Ultimates (both hi-Z and lo-Z). I detect no erosion of tone attributable to the VC. What the VC does allow me to do is get better tone out of my tube amps. The VC enables me to drive the amp harder while I control performance volume and feedback by attenuating the input signal with the VC.
|
Harpaholic
798 posts
Jan 27, 2016
3:40 PM
|
Even though I disagree with Greg, I have owed two of his inline VC"s for 2-3 years now. There top knotch, and the difference in tone is minimal. In a band situation unnoticeable.
Every harp player should use one to control feedback, soloing, and when the guitar player/players turn up, and they will!
I also own two of the other brand on the market. Neither of the two lasted a year.
I had to replace both pot's. When I opened them up, I found the cheap miniature Alpha Tawain pots.
I use 100K and 1 meg based on the old Shure and Astatic minimum requirements.
I prefer the sweep of an audio taper pot when installed in a mic shell. 100K and 1 meg gives me a little more sweep without any noticable difference in tone compared to higher value pots.
Last Edited by Harpaholic on Jan 27, 2016 11:26 PM
|
Kingley
3997 posts
Jan 27, 2016
10:20 PM
|
I don't think the volume controls affect tone discernibly in a live gig setting. The only mic I have with one on is an Ultimate 545, because they come as standard with them fitted. Personally I only use it as an on/off switch. I can understand why some people like them though and wouldn't rule out using them if the situation warranted it.
|
Barley Nectar
1091 posts
Jan 28, 2016
7:45 AM
|
The RCA handbook states that a crystal wants to see 3M minimum load for best bass response. Remember also that your VC is in parallel with the resistors in the input of an amp. So, your mic element is not seeing the VC R alone. Using the #1 jack on a Champ and a 250K VC in the mic, my calculations show that the mic is seeing a 210.69K load. This will not bother most high Z dynamic elements such as CM/CR. I typically change the input R to 5M on my amps but this in not necessary with dynamic mics.
I know one thing for sure, the drunks in a bar will never know the difference! (;>)...BN
Last Edited by Barley Nectar on Jan 28, 2016 8:11 AM
|
Harpaholic
802 posts
Jan 28, 2016
9:00 AM
|
RCA never manufactured crystals as far as I know.
Shure recommended 5 meg, Astatic recommended 1 and 5 Meg depending on the time period.
Using a 5 Meg input and a 1 Meg audio pot, my ears don't hear any difference. Maybe it's old age?
Barley, with a 5 Meg amp input using a 1 Meg pot could you tell me what load a mic is seeing?
3 Meg?
All of my amps are modded with one 5 Meg input for crystals usually on the mic channel.
Last Edited by Harpaholic on Jan 28, 2016 9:16 AM
|
Barley Nectar
1092 posts
Jan 28, 2016
9:58 AM
|
http://www.sengpielaudio.com/calculator-paralresist.htm
833.3K
The RCA handbook, officially named, "Radiotron Designer's Handbook" copyright 1953, has nothing to do with who made what. This is the tube amp and radio bible and applies to all things tube to this day...BN
|
Barley Nectar
1093 posts
Jan 28, 2016
10:10 AM
|
OK, I reviewed the article. For diaphragm type crystal mics the grid resistor, (load) should be between 1-5 meg ohms...BN
|
Harpaholic
803 posts
Jan 28, 2016
10:46 AM
|
Thanks Barley! I am very familiar with the RCA handbook. I have referenced their vintage tube data countless times.
Shure and Astaic say the exact same thing with a 5 Meg minimum.
Barley, you just brought up the single most important part of this whole conversation!
Your a Genius!
If your amp input is too low for a crystal as is most vintage amps, a 5 Meg pot wouldn't be enough.
So running my crystal with a 1 Meg pot into a 5 Meg amp input is identical to anyone else running a crystal with a 5 Meg pot into a stock Bassman RI.
I don't notice any low frequency loss, but
fortunately none of my amps have lack of bass and/or have a tone stack to compensate.
This is copied and pasted from 1949 Shure 707A data sheet for those interested.
Connections: The inner or “hot” conductor of the cable should be connected to the grid of the first tube in the amplifier across a load resistance of 5 megohms. Input resistances as low as 1 megohm may be used if necessary but higher values are recommended because of better low-frequency response obtained. The shield should be connected to the amplifier chassis or ground. The shield, chassis or amplifier ground should be securely grounded to a water pipe or similar ground to prevent shock hazard during operation of the amplifying system. The cable may be lengthened if desired; low capacity shielded microphone cable should be used for this purpose.
Last Edited by Harpaholic on Jan 28, 2016 10:56 AM
|
Harpaholic
804 posts
Jan 28, 2016
11:07 AM
|
Thanks to Barley I now know It would take a 10 Meg amp input with a 10 Meg pot for a crystal to see a 5 Meg load.
More realistic would be a 5 Meg input with a 5 Meg VC. The crystal would see a 2.5 Meg load. Probably fine for the human ear.
|
Barley Nectar
1094 posts
Jan 28, 2016
12:13 PM
|
LOL, I'm no genius I assure you but thank you Harpaholic. My info comes from others and from old books, others also! I just try and pass it on or get people to research on their own. This is my contribution to the forum. Understanding what is going on with your gear is important if you play live. Messing with ancient technology is fascinating to me...BN
|
SuperBee
3307 posts
Jan 28, 2016
1:02 PM
|
Thats all good, i feel i'm starting to understand this at last.
|
Mojokane
852 posts
Feb 01, 2016
1:34 PM
|
I'm with Greg's comments. Use em all the time. It's rare when I make a custom mic for someone, and they tell me don't put a vc. Any questions, see Greg.
The pros far out weigh the cons.
----------
Yes, there are blues in Hawaii.
Last Edited by Mojokane on Feb 01, 2016 1:35 PM
|
