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Offline tapers_are_geeks

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yet another sp preamp ?
« on: April 14, 2006, 03:36:54 PM »
is this a gain control knob or a line level volume control?i've been reading around and read with line level volume control that no matter the db gain is switch to it is always sending that much db gain to the recording unit which can cause brickwalling. isn't this the case with sp pre's? with the switch on 29db gain that the level control knob doesn't control the gain only the amount of volume. this is prolly not good for my app.. i need a true gain control knob not a level volume control knob..

if the switch is on 29db and i only need 15db im prolly gonna run into brickwalling problems with the level control.

the sp pre will not adjust this only a true gain control knob like the boost box will or Church pre?

insight on this knob control would be of much help. i have level control on the recorder. i beleive i need a true gain control knob.

has anyone used Church's 0>20db preamp with the gain control knob? Church says that his unti offers a true gain control knob from 0>20db

if sp will make a true gain control knob from 0>29db it would boost sells tremendously. if this is only a volume control knob 29db is going to be way to much for amplified recordings. i only need 15db of gain at the most and this is for big outdoor venues..

Offline scoper

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Re: yet another sp preamp ?
« Reply #1 on: April 14, 2006, 07:05:51 PM »
Please explain the difference between gain and volume, as it relates to preamps and the sending of signal to a recording device.
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Offline Church-Audio

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Re: yet another sp preamp ?
« Reply #2 on: May 04, 2006, 01:32:33 AM »
I think what he is trying to say is that, there are preamps that have a gain switch that effects the actual gain of the preamp. And there are some that use volume controls where they have a gain switch that sets the over all gain and then a volume control for reducing the level going to the recording device. We make two different types of preamp, our basic preamp the ST-9000 has a gain switch of 0-db +10db +30 db and then a volume control to adjust the output of the preamp, so that it does not overload the input of the recording device. We Also make a preamp with a true gain control that covers from 00- db or off to +20 db, this we find is most useful for people recording loud bands with sensitive mics and it comes in a 3 wire or 2 wire config.

Chris Church


Please explain the difference between gain and volume, as it relates to preamps and the sending of signal to a recording device.
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Offline scoper

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Re: yet another sp preamp ?
« Reply #3 on: May 04, 2006, 08:34:08 AM »
Thanks, Chris...

Now if you could explain why having it one way is better than the other? The SP preamps offer stepped gain ranges (usually 0/29/50), and a "volume control", which if I understand is simply an attenuator. The net effect is the same - the recording device gets the proper amount of amplification, so what's the difference?

Scott
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Offline Javier Cinakowski

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Re: yet another sp preamp ?
« Reply #4 on: May 04, 2006, 08:42:01 AM »
Quote
Thanks, Chris...

Now if you could explain why having it one way is better than the other? The SP preamps offer stepped gain ranges (usually 0/29/50), and a "volume control", which if I understand is simply an attenuator. The net effect is the same - the recording device gets the proper amount of amplification, so what's the difference?

I am no expert, but from what I understand the added volume control (attenuation) is an added step in the signal chain.  It could add noise and other problems. 
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Offline Church-Audio

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Re: yet another sp preamp ?
« Reply #5 on: May 04, 2006, 10:47:07 AM »
Hi the best solution is a true gain control but preamps that are designed well with fixed toggle switches for gain control and an output level control will work just as well we use 0 db and +10 db and +30 db we feel for recording concerts and accoustic stuff that about covers the ranges you need. We also make a +20 db preamp that has a true gain control this is good for loud situations where you want to get as much gain out of the preamp as possible. It produces a very Fat sound because it is class A and because it uses a burr brown op amp both types of preamps work well designed properly. So I guess to answer your question they are both good. There has been talk about the volume control adding noise thisis not true if the preamp is quiet and you attenuate the output with a volume control your not adding noise your attenuating a signal.

Chris Church



Thanks, Chris...

Now if you could explain why having it one way is better than the other? The SP preamps offer stepped gain ranges (usually 0/29/50), and a "volume control", which if I understand is simply an attenuator. The net effect is the same - the recording device gets the proper amount of amplification, so what's the difference?

Scott

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Offline Church-Audio

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Re: yet another sp preamp ?
« Reply #6 on: May 04, 2006, 10:57:35 AM »

Attenuation is an added step but in most cases its passive so it will not add noise....... however the cheap headphone attenuators that some people are using will add noise, and this is to do with the fact that A- its a carbon film resistor and B- that it is not followed by a preamp but by a mic with a tiny fet in it. We make a preamp that has an attenuator built in it comes After the gain stage this means that your not attenuating a signal and then asking a preamp to boost it. This will increase noise we do it after the gain stage of the preamp so that you’re just attenuating the signal. There are some that attenuate the signal before the gain stage we feel that this is not a good idea, with small battery operated preamps. We have our gain switch in the feedback loop of the preamp so that it controls the op amps over all gain. That is the best way to control gain. Some people just make a preamp that does 30 db all the time and then reduce the output this will always result in increased distortion and poor signal to noise specs. IMO And that is where the myth that attenuation increases noise comes from if you attenuate before the preamp you will get noise, because you will be forced to use more gain and you will bring up the noise floor at the same time you bring up the gain.

Chris Church


Quote
Thanks, Chris...

Now if you could explain why having it one way is better than the other? The SP preamps offer stepped gain ranges (usually 0/29/50), and a "volume control", which if I understand is simply an attenuator. The net effect is the same - the recording device gets the proper amount of amplification, so what's the difference?

I am no expert, but from what I understand the added volume control (attenuation) is an added step in the signal chain.  It could add noise and other problems. 
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Offline funk_pie

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Re: yet another sp preamp ?
« Reply #7 on: May 04, 2006, 11:34:39 AM »
nice, i've been waiting for someone to explain it like that!
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Re: yet another sp preamp ?
« Reply #8 on: May 04, 2006, 11:40:38 AM »
Yep, thanks for the respose Chris.  That explains it perfectly.

BTW, what op-amps are used in your stc900 series preamp like I have?  I asked you before but I cannot remeber.  i dont think it was the burr-brown.  thanks,   +T
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Re: yet another sp preamp ?
« Reply #9 on: May 04, 2006, 11:52:23 AM »
Some of them are NE5532 some of the newer ones are burr brown and some of the older ones were tlo72 or tlo82 the ne5532 and the burr brown are very close in specs but I like the burr brown yours I looked it up was a burr brown



Yep, thanks for the respose Chris.  That explains it perfectly.

BTW, what op-amps are used in your stc900 series preamp like I have?  I asked you before but I cannot remeber.  i dont think it was the burr-brown.  thanks,   +T
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Re: yet another sp preamp ?
« Reply #10 on: May 04, 2006, 12:02:55 PM »
Quote
Some of them are NE5532 some of the newer ones are burr brown and some of the older ones were tlo72 or tlo82 the ne5532 and the burr brown are very close in specs but I like the burr brown yours I looked it up was a burr brown

Thanks for the response. 

I really like your preamp.  It sounds great with my SenMKE40s.  I am in the market for a set of Omni's to run with my stc9000 preamp.  I want the Omni's for shows with very little crowd noise.  Also I need the full bass of an Omni mic as a band I tape does not have much bass to begin with.    The DPA's are out of my price range and I dislike Core-Sound. I have a set of those Radio Shack mini-electret omni's.  They actually sound really good considering who they are made by. 

Any suggestions?
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Re: yet another sp preamp ?
« Reply #11 on: May 04, 2006, 01:29:44 PM »
My new B-99M is a great omni with 20 to 20 response and I can sell you a pair for $99.99 they have been tested out to 114 db with a distortion of less then 0.5%!

Quote
Some of them are NE5532 some of the newer ones are burr brown and some of the older ones were tlo72 or tlo82 the ne5532 and the burr brown are very close in specs but I like the burr brown yours I looked it up was a burr brown

Thanks for the response. 

I really like your preamp.  It sounds great with my SenMKE40s.  I am in the market for a set of Omni's to run with my stc9000 preamp.  I want the Omni's for shows with very little crowd noise.  Also I need the full bass of an Omni mic as a band I tape does not have much bass to begin with.    The DPA's are out of my price range and I dislike Core-Sound. I have a set of those Radio Shack mini-electret omni's.  They actually sound really good considering who they are made by. 

Any suggestions?
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Offline scoper

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Re: yet another sp preamp ?
« Reply #12 on: May 04, 2006, 03:02:52 PM »

Attenuation is an added step but in most cases its passive so it will not add noise....... however the cheap headphone attenuators that some people are using will add noise, and this is to do with the fact that A- its a carbon film resistor and B- that it is not followed by a preamp but by a mic with a tiny fet in it. We make a preamp that has an attenuator built in it comes After the gain stage this means that your not attenuating a signal and then asking a preamp to boost it. This will increase noise we do it after the gain stage of the preamp so that you’re just attenuating the signal. There are some that attenuate the signal before the gain stage we feel that this is not a good idea, with small battery operated preamps. We have our gain switch in the feedback loop of the preamp so that it controls the op amps over all gain. That is the best way to control gain. Some people just make a preamp that does 30 db all the time and then reduce the output this will always result in increased distortion and poor signal to noise specs. IMO And that is where the myth that attenuation increases noise comes from if you attenuate before the preamp you will get noise, because you will be forced to use more gain and you will bring up the noise floor at the same time you bring up the gain.

Perfect explanation, Chris... thanks very much! +T

Scott
« Last Edit: May 04, 2006, 03:05:56 PM by scoper »
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Offline anechoic

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Re: yet another sp preamp ?
« Reply #13 on: May 10, 2006, 02:50:07 PM »
what capsules do you use in the B-99M? are they Panasonics?


My new B-99M is a great omni with 20 to 20 response and I can sell you a pair for $99.99 they have been tested out to 114 db with a distortion of less then 0.5%!

Quote
Some of them are NE5532 some of the newer ones are burr brown and some of the older ones were tlo72 or tlo82 the ne5532 and the burr brown are very close in specs but I like the burr brown yours I looked it up was a burr brown

Thanks for the response. 

I really like your preamp.  It sounds great with my SenMKE40s.  I am in the market for a set of Omni's to run with my stc9000 preamp.  I want the Omni's for shows with very little crowd noise.  Also I need the full bass of an Omni mic as a band I tape does not have much bass to begin with.    The DPA's are out of my price range and I dislike Core-Sound. I have a set of those Radio Shack mini-electret omni's.  They actually sound really good considering who they are made by. 

Any suggestions?
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Re: yet another sp preamp ?
« Reply #14 on: May 10, 2006, 03:09:49 PM »
what capsules do you use in the B-99M? are they Panasonics?

My new B-99M is a great omni with 20 to 20 response and I can sell you a pair for $99.99 they have been tested out to 114 db with a distortion of less then 0.5%!

If they are how do you match them?  Do you do what others do, and spend about $20+/- and just measure resistance across the terminals?  That's what I did, and $5 more and I had a nice little pair of omnis.  YMMV
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Re: yet another sp preamp ?
« Reply #15 on: May 10, 2006, 03:41:59 PM »
Resistance does not tell you anything, you can have two capsules that are 666 and because of the diaphragm tension they put out very different output levels.

 I use a db meter calibrator B&K that puts out 1k at 114 db ( I have had a machined coupler for 6mm, 3mm,10mm and 12mm capsules) I then measure the signal level coming out of the capsule and match them to with in 0.01% of a db. I have a very accurate signal level meter it takes about $2,000 to have the set up I use just for matching level on capsules. Resistance will tell you that the FET has the same internal resistance but not the same output. But it does get you close. Many microphone companies use the same method I do for matching capsules. It is still not as accurate as full range matching but not nearly as expensive.

Chris Church
Hope that helps


quote author=O-Canis link=topic=63054.msg863171#msg863171 date=1147288189]
what capsules do you use in the B-99M? are they Panasonics?

My new B-99M is a great omni with 20 to 20 response and I can sell you a pair for $99.99 they have been tested out to 114 db with a distortion of less then 0.5%!

If they are how do you match them?  Do you do what others do, and spend about $20+/- and just measure resistance across the terminals?  That's what I did, and $5 more and I had a nice little pair of omnis.  YMMV
[/quote]
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EMAIL Sales@church-audio.com

 

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