At your risk.
Always use a fuse in series with a battery for fire hazard protection.
It has always been a mystery to me why connecting a state of the art flat frequency response mic to a flat frequency response recording system makes a vocal reproduction sounding like mud with bass heaviness.
Nothing is wrong with the equipment but the bass heaviness takes place in our brain as in pop music we usually try to reproduce a softer singing voice at a higher sound pressure level [Lowe, Morgan].
(It has been a privilege to find the engineering answer on this paper).
In order to remove something offensive the first step is clearly hearing it and the new Pleiades setup makes this a piece of cake.
The setup used sounds great on commercial FM radio but immediately showed very severe bass heaviness and mid heaviness problems while recording and reproducing on 1/4in analog magnetic tape.
Signal path:
Uher 4200 report stereo 1/4 in tape recorder (1st bought on eBay) - JVC 9425W radio used as bass boost amplifier for small speakers - Pleiades linoleum Auratone type 5C monitoring speaker
Almost everything tried in terms of microphones used including Pleiades filters (for bass reduction) sounded horrible with extreme bass heaviness and sounding so far from a commercial recording by direct comparison. The comparison is done by just removing the AUX in connector from the JVC radio and immediately listening to any commercial pop song on the radio with the same reproducing system.
So it was decided today to use a Pleiades V1 CV2269 electrometer electron tube mic front end amplifier operating at so low anode current that there is another bass cut filter right at the anode from the inductance of the output transformer.
It turned out that it still sounded bass and mid heavy.
So then a Pleiades (130Ω,40mH) filter was added to the input (after the mic). With these 2 low cut filters the singing voice started coming out very natural with shinning detail or lack of bass or mid bass, or mid heaviness. This setup revealed the great detail of the Fostex M80RP microphone.
This is the complete setup including the recording path:
Singer's brain - not heavily treated living room - male singing voice - microphone - Pleiades (130Ω,40mH) gentle low cut filter - Pleiadss V1 CV2269 with Altec input transformer and Pleiadss output 10:1 transformer - Uher 4200 (1st bought from eBay) - BASF EMTEC SM911 tape - Uher 4200 (1st bought) reproducing - JVC Nivico 9425W as amplifier or radio amplifier - Pleiades linoleum Auratone type 5C monitoring speaker hung from ceiling - same living room - listener's brain
Why not using just a recording console and its tone controls for reducing bass heaviness?(br />
The objective is using as few as possible (class A ie electrons flowing all the time) active device gain stages from mic to tape. For the sake of keeping as much freshness and clarity of the voice.
The device count in the above setup is about 1 electron tube and about 2 transistors.
Below are further details of some signal path components so that results can hopefully be repeatable:
The Uher 4200 (1st bought with new Fujitsu D batteries) had been used instead end of (4th) as the latter produced low frequency hiss possibly due to aging batteries.
The Pleiades V1 CV2269 was used in breadboard jig form. The Altec green octal bass transformer was used as input transformer. A freshly charged Recyco green 1.2V battery for heater cathode and plate.
Anode current on V1 CV2269 is 10μA.
Altec Lansing 4722 is the input transformer.
22nF blue MKT Philips? is the coupling capacitor to grid.
19.7MΩ is anode to grid pull up bias resistor.
1.2V from a freshly changed AA Recyco battery is Va and Vb ie filament and anode supply.
The output transformer is a Pleiades 77H : 800mH (672 turns to 70 turns) wound on Magnetec 070 toroid tape wound nanoperm core.
Later addition: M80RP - Pleiades (130Ω,40mH) - German 500Ω:600Ω inline transformer - Uher 4200 report had been tried too but it still sounded a bit bass heavy.
Another option to try might be 2 omni mics connected out of phase (Dscribed in Lou Burroughs Microphones book). Just one 635a with Pleiades (130Ω,40mH) still sounded bass heavy.
Reference:
Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - Journal of the Society of Motion Picture Engineers
Always use a fuse in series with a battery for fire hazard protection.
It has always been a mystery to me why connecting a state of the art flat frequency response mic to a flat frequency response recording system makes a vocal reproduction sounding like mud with bass heaviness.
Nothing is wrong with the equipment but the bass heaviness takes place in our brain as in pop music we usually try to reproduce a softer singing voice at a higher sound pressure level [Lowe, Morgan].
(It has been a privilege to find the engineering answer on this paper).
In order to remove something offensive the first step is clearly hearing it and the new Pleiades setup makes this a piece of cake.
The setup used sounds great on commercial FM radio but immediately showed very severe bass heaviness and mid heaviness problems while recording and reproducing on 1/4in analog magnetic tape.
Signal path:
Uher 4200 report stereo 1/4 in tape recorder (1st bought on eBay) - JVC 9425W radio used as bass boost amplifier for small speakers - Pleiades linoleum Auratone type 5C monitoring speaker
Almost everything tried in terms of microphones used including Pleiades filters (for bass reduction) sounded horrible with extreme bass heaviness and sounding so far from a commercial recording by direct comparison. The comparison is done by just removing the AUX in connector from the JVC radio and immediately listening to any commercial pop song on the radio with the same reproducing system.
So it was decided today to use a Pleiades V1 CV2269 electrometer electron tube mic front end amplifier operating at so low anode current that there is another bass cut filter right at the anode from the inductance of the output transformer.
It turned out that it still sounded bass and mid heavy.
So then a Pleiades (130Ω,40mH) filter was added to the input (after the mic). With these 2 low cut filters the singing voice started coming out very natural with shinning detail or lack of bass or mid bass, or mid heaviness. This setup revealed the great detail of the Fostex M80RP microphone.
This is the complete setup including the recording path:
Singer's brain - not heavily treated living room - male singing voice - microphone - Pleiades (130Ω,40mH) gentle low cut filter - Pleiadss V1 CV2269 with Altec input transformer and Pleiadss output 10:1 transformer - Uher 4200 (1st bought from eBay) - BASF EMTEC SM911 tape - Uher 4200 (1st bought) reproducing - JVC Nivico 9425W as amplifier or radio amplifier - Pleiades linoleum Auratone type 5C monitoring speaker hung from ceiling - same living room - listener's brain
Why not using just a recording console and its tone controls for reducing bass heaviness?(br />
The objective is using as few as possible (class A ie electrons flowing all the time) active device gain stages from mic to tape. For the sake of keeping as much freshness and clarity of the voice.
The device count in the above setup is about 1 electron tube and about 2 transistors.
Below are further details of some signal path components so that results can hopefully be repeatable:
The Uher 4200 (1st bought with new Fujitsu D batteries) had been used instead end of (4th) as the latter produced low frequency hiss possibly due to aging batteries.
The Pleiades V1 CV2269 was used in breadboard jig form. The Altec green octal bass transformer was used as input transformer. A freshly charged Recyco green 1.2V battery for heater cathode and plate.
Anode current on V1 CV2269 is 10μA.
Altec Lansing 4722 is the input transformer.
22nF blue MKT Philips? is the coupling capacitor to grid.
19.7MΩ is anode to grid pull up bias resistor.
1.2V from a freshly changed AA Recyco battery is Va and Vb ie filament and anode supply.
The output transformer is a Pleiades 77H : 800mH (672 turns to 70 turns) wound on Magnetec 070 toroid tape wound nanoperm core.
Later addition: M80RP - Pleiades (130Ω,40mH) - German 500Ω:600Ω inline transformer - Uher 4200 report had been tried too but it still sounded a bit bass heavy.
Another option to try might be 2 omni mics connected out of phase (Dscribed in Lou Burroughs Microphones book). Just one 635a with Pleiades (130Ω,40mH) still sounded bass heavy.
Reference:
Sound Picture Recording and Reproducing Characteristics - D. P. Lowe, K. F. Morgan - Journal of the Society of Motion Picture Engineers
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