This one has kind of snuck up on me: the inputs seem to have almost zero gain until they are turned almost all the way up. That is, until about the four or five o'clock position, nothing. Can I do anything about this? Thank you.
Bad Input Pots?
- Thread starter Craig Jolly
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Mark Richards
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The DP-xx doesn't have physical volume controls for the INPUT SOURCES (caps used for clarity).
If you're referring to the 8 TRIM KNOBS, those are not volume controls. They are continuously variable pads that serve two purposes:
(1) set the TRS phone jack inputs to the high impedance "LINE" level or set the balanced XLR jack inputs to low impedance "MIC" level; and
(2) attenuate a too hot mic signal when the XLR/MIC inputs are used.
If the rotary pads were instead fixed switch pads, they would be marked left to right as: "Line" on the far left; "-40dB Mic" inner left; "-20dB Mic" inner right; and "Mic" on the far right.
If you have a weak "MIC" signal, move the mic closer to the instrument/vocalist or have the instrument/vocalist play/sing louder.
If you have a weak "LINE" signal, raise the output level of the line level device connected to the DP-xx.
If you're referring to the 8 TRIM KNOBS, those are not volume controls. They are continuously variable pads that serve two purposes:
(1) set the TRS phone jack inputs to the high impedance "LINE" level or set the balanced XLR jack inputs to low impedance "MIC" level; and
(2) attenuate a too hot mic signal when the XLR/MIC inputs are used.
If the rotary pads were instead fixed switch pads, they would be marked left to right as: "Line" on the far left; "-40dB Mic" inner left; "-20dB Mic" inner right; and "Mic" on the far right.
If you have a weak "MIC" signal, move the mic closer to the instrument/vocalist or have the instrument/vocalist play/sing louder.
If you have a weak "LINE" signal, raise the output level of the line level device connected to the DP-xx.
Last edited:
.Strat Brat
Active Member
For some reason I find it easier to regard the trim knobs as volume controls for the input into the DP24SD, coming from connected musical instruments, and the fader slide controls as the volume knobs for the output from the DP24SD to the tracks being mixed down, or to the headphones/speakers.
Mark Richards
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.Strat Brat,
Think of impedance in terms of water flowing through a pipe. The larger the pipe, the greater the volume of water that can pass through the pipe, from minimum flow to maximum flow, without backing up. You never want the incoming flow of water to exceed the flow capacity of the pipe.
The XLR jack is low impedance (2.4 kOhm). This is mic level - all mics with XLR cables are low impedance.
The 1/4" TRS phone jack is high impedance (>22 kOhm). This is line level.
The Input H "guitar" switch converts the 1/4" phone jack impedance from 22 kOhms to 1 mOhm (1 million Ohms). This allows for either plugging the guitar in directly, or running the guitar through a bunch of effects pedals first. The guitar itself is high impedance (typically 40kOhm), and each effects pedal adds its own high impedance to the signal flow.
It's okay generally to run a low impedance device (like a mic) into a high impedance input. The only downside is lower sound level/more noise in the mic signal than there would be when pairing the low impedance mic with the low impedance input.
Musical instruments are all high impedance. The proper way to record them on the DP-xx is as I described in my post above. The reason is that when a high impedance source is connected to the high impedance TRS phone jack and the Trim Pot is ~not~ in the "Line" position, the impedance is set to mic level and the mismatch can result in loss of high frequencies and other forms of signal distortion. Also, if the musical instrument has a pre-amp to boost its output signal, the impedance mismatch can place unwanted stress on the electrical components of the input that can result in component failure over time.
Think of impedance in terms of water flowing through a pipe. The larger the pipe, the greater the volume of water that can pass through the pipe, from minimum flow to maximum flow, without backing up. You never want the incoming flow of water to exceed the flow capacity of the pipe.
The XLR jack is low impedance (2.4 kOhm). This is mic level - all mics with XLR cables are low impedance.
The 1/4" TRS phone jack is high impedance (>22 kOhm). This is line level.
The Input H "guitar" switch converts the 1/4" phone jack impedance from 22 kOhms to 1 mOhm (1 million Ohms). This allows for either plugging the guitar in directly, or running the guitar through a bunch of effects pedals first. The guitar itself is high impedance (typically 40kOhm), and each effects pedal adds its own high impedance to the signal flow.
It's okay generally to run a low impedance device (like a mic) into a high impedance input. The only downside is lower sound level/more noise in the mic signal than there would be when pairing the low impedance mic with the low impedance input.
Musical instruments are all high impedance. The proper way to record them on the DP-xx is as I described in my post above. The reason is that when a high impedance source is connected to the high impedance TRS phone jack and the Trim Pot is ~not~ in the "Line" position, the impedance is set to mic level and the mismatch can result in loss of high frequencies and other forms of signal distortion. Also, if the musical instrument has a pre-amp to boost its output signal, the impedance mismatch can place unwanted stress on the electrical components of the input that can result in component failure over time.
Last edited:
.Strat Brat
Active Member
This clarifying explanation is much appreciated, Mark. I have cut and pasted your explanation kindly provided above, and added it to my growing file of pointers on the use of the DP24SD.
As a hobbyist guitar meddler, with virtually no experience in recording, besides my trial-and-error bumbling efforts using my DP08SD, an overview of the various input connections applicable to the DP24SD, is a summary that I will likely reference often, as my musical experiments continue apace.
Much thanks for taking a moment to simplify a sometimes baffling concept, enabling me and other less experienced Tascam owners to cut to the chase, as it were.
As a hobbyist guitar meddler, with virtually no experience in recording, besides my trial-and-error bumbling efforts using my DP08SD, an overview of the various input connections applicable to the DP24SD, is a summary that I will likely reference often, as my musical experiments continue apace.
Much thanks for taking a moment to simplify a sometimes baffling concept, enabling me and other less experienced Tascam owners to cut to the chase, as it were.
