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N0CIC
12-28-2007, 04:43 PM
I have a Astatic 10-DA mic that I run on a Kenwood TS-440s
I have reports that the mic has too much base. Is there a mod that I can do to make it sound better?

VE2NSM
12-28-2007, 05:40 PM
Too much bass or not enough treble? There is often misconception about this.

AG3Y
12-28-2007, 05:58 PM
The elements of microphones often have air pressure relief holes on the back side of the diaphram. Some or all of these holes can often be partially or fully covered with tape to change the bass characteristics of a microphone.

NSM raises a good question, although I doubt that many microphones would be lacking in treble enough to be noticable through an SSB transmitter.

I was playing around with a microphone the other day that was waaaay too bassy. I covered over half the pressure relief holes in the element case, and made a rather good sounding microphone out of it. Its only problem now is that the element is very sensitive to "handling noise". Every little movement makes very pronounced scratching and scraping noises. No, it is not the cable, which is in fine shape. Putting the mic in a holder makes it work just fine !

If you can get to the element without distroying the mic, I would certainly recommend experimenting with it. That is part of what ham radio is all about !

Good luck, 73, Jim

VE2NSM
12-28-2007, 06:23 PM
Quote[/b] (AG3Y @ Dec. 28 2007,13:58)]NSM raises a good question, although I doubt that many microphones would be lacking in treble enough to be noticable through an SSB transmitter.
Often when it happens it's a matter of impedance, like a high Z microphone made for old radios (like the astatic 10DA) connected to a low Z input made for dynamic mics.

K8ERV
12-28-2007, 07:39 PM
I think he is having "trouble with trebbles". (ouch)

TOM K8ERV Montrose Colo

N0CIC
12-29-2007, 02:16 AM
If the Astatic 10-da is a high z mic. is there a mod that will change it to a low z mic?

W9GB
12-29-2007, 03:27 AM
Quote[/b] ]If the Astatic 10-DA is a high-Z mic. is there a mod that will change it to a low-Z mic?
William -

The Astatic 10-DA is suppose to be a Dynamic mirophone element -- designed for SSB usage.
http://users.pandora.be/oldmicrophones/thumb_astatic_10da.htm

IF you have a Hi-Z output from the microphone (through the base you are using) then a Hi-Z to Lo-Z audio transformer will address the issue. (Heil, Mouser, etc. carry this item)

w9gb

W6GQ
12-29-2007, 05:27 AM
http://forum.worldwidedx.com/viewtopic.php?t=7997

W2VW
12-29-2007, 01:48 PM
The linky hits the solution. If you have plenty of gain available then try some capacitive reactance in series with the mic lead. That will change the frequency response. Try a .1 mylar capacitor for starters. That might be too much maybe 1/2 or 1/3rd that value. It will take experimentation. Same idea as a high pass filter for a tweeter in a speaker crossover network. If you use too small a value the audio will sound very thin.

You might want to try another mic with similar specifications to be sure your 10DA isn't a dud.

KC9GUZ
12-29-2007, 03:51 PM
Hmmm i have a 10 da head and the mike element doesnt have any holes in the back of it. I think mine is an older version though. The later ones used a plastic cartridge.

AG3Y
12-29-2007, 04:36 PM
The suggestion about the holes was just generic. Blocking the holes in most mic elements will increase the damping, and lower the bass frequency response.

A comment about "impedance matching". Generally, if you try to feed a high-impedance mic into a low impedance input, besides the amplitude loss due to the mismatch, your frequency response will suffer in the bottom frequencies, not the top ! A good example is the famous un-amplified D-104 with the crystal element. They may sound good on a "boatanchor" where the only load put on them is the grid-load resistor ( generally somewhere around a half meg ), but sound terrible on a modern rig with medium to low input impedance. Harsh treble, and little or no bass. They were NOT designed to sound that way!

Well, anyway, if the pressure relief holes are not present on the back of your element, you don't have to worry about it. Just keep it in mind for some microphone you may come across in the future!

73, Jim

K7KBN
12-29-2007, 05:26 PM
Quote[/b] (K8ERV @ Dec. 28 2007,11:39)]I think he is having "trouble with trebbles". (ouch)

TOM K8ERV #Montrose Colo
That episode took place on "Deep Space Station K7".

I kept waiting for the "KBN" after the "K7", but it never came http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

VE2NSM
12-29-2007, 06:32 PM
Quote[/b] (AG3Y @ Dec. 29 2007,12:36)]A comment about "impedance matching". Generally, if you try to feed a high-impedance mic into a low impedance input, besides the amplitude loss due to the mismatch, your frequency response will suffer in the bottom frequencies, not the top ! A good example is the famous un-amplified D-104 with the crystal element. They may sound good on a "boatanchor" where the only load put on them is the grid-load resistor ( generally somewhere around a half meg ), but sound terrible on a modern rig with medium to low input impedance. Harsh treble, and little or no bass. They were NOT designed to sound that way!
True, depending on the configuration of the input and the type of source this can happen. If the source becomes capacitive or inductive when connected to a heavy load, it will tend to attenuate either the high frequencies or the low frequencies.

For my part and the audio work I do, the high frequency loss happens much more often than the opposite... Different strokes for different folks http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif

N0CIC
12-29-2007, 06:48 PM
Opened up the mic and found that there is a audio transformer mounted in the mic head. The # on it is B-9389-1
The mic is an Astatic MC 563
There are no holes in the mic for pressure relief.
Looked at Digikey but could not decide which audio transformer would work to make the mic a low-Z

K8JD
12-29-2007, 11:02 PM
When I bought my used TS440S, the previous owner supplied a Kenwood mic that had no number on it . has 2 buttons marked up and down on the top. On the rare occations that I get on fone, such as 10M FM, I always get good audio reports. If you can find a plain Kenwood hand held mike you would be able to sell that D104 to a CBer for big bucks, and have decent sounding audio.
I also have a TS520 and when I want to get on SSB with it, I have a Radioshack mic buried in a drawer somewhere and it always sounds great to whowver is at the other end.

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