Topic: DPA MPS6010

[jerryfreak]

can this circuit be tweaked?

its a dual purpose battery box that can either transform P48 from the xlrs into microdot power, or use the 9V to provide microdot power. problem being, like other DPA solutions its drops the voltage from 9V to ~2.5V under load. Ive been told by Bruce Myers and Len and others that best results for mini DPAs is ~8V. Im not sure about the new microdot-powered full sized actives, hard to get a straight answer from DPA anymore

so id like to:
a)increase voltage to mic by swapping some resistors
b)pull off an unbalanced out and put a female trs jack in the case. would i just pull off pin 2 and leave pin 3 float in that case?

the red caps are larger than the purple ones. red are non-polarized, purple are polarized, both are 50V 10uF. From the XLRs black=pin1, red=pin2, yellow=pin3. the black and red wires at the top of the first pic go to the microdot mic connectors

the entire perimeter of that board layout as well as the two cross-connections under the resistors are all ground common to the battery, XLRs, and microdot connections

not sure what the small gold things are, i get random resistance measurements on those which should be a symmetrical 2-channel circuit. are they small caps or something?

[jerryfreak]

some of the hidden traces illustrated in pink

[Sebastian]

not sure what the small gold things are, i get random resistance measurements on those which should be a symmetrical 2-channel circuit. are they small caps or something?

Could these be diodes?

[jerryfreak]

not sure what the small gold things are, i get random resistance measurements on those which should be a symmetrical 2-channel circuit. are they small caps or something?

Could these be diodes?

interesting ill test them with diode beep tester

[H₂O]

They look like diodes to me. - The black ring is the output side (or what points in the direction of current flow) - You do get a voltage drop across any diode and it can be substantial


Usually in power supplies they are used either for protection or slight voltage adjustments or both


Also note that the caps in the pics look like typical electrolytic caps which are almost always polarized - see [size=78%]https://en.wikipedia.org/wiki/Electrolytic_capacitor[/size]
[/size][size=78%]  [/size]

[H₂O]

They are called glass diodes

[jerryfreak]

They are called glass diodes

makes sense. its not apart right now, and opposite ones did show OL across them (as opposed to the symmetrical diode on the other channel that i was measuring with correct polarity)

[Len Moskowitz (Core Sound)]

(This will get technical.)

It's not quite correct to think that a capsule's power supply must always stay at a specific voltage. It's a Power supply - meaning a Watt supply - not a Volt supply.

When you see the voltage drop when the capsule is exposed to a loud sound source, what you're seeing is that it's drawing more current across the power supply's (the battery) internal series resistor. (The resistor may function as a current limiting resistor.) That's perfectly fine as long as the power supply can supply enough current, and the resulting under-load voltage is adequate to allow the capsule to capture the sound pressure level without distorting. So the ~2.5V you're measuring might be just fine.

Assuming that your voltage source (the battery again) can provide enough current, selecting the right voltage is an exercise in selecting a voltage that's high enough to allow for high sound pressure levels, and not so high that it will destroy the FET inside that capsule. Equally important is the value of the series resistor. Like much of engineering, it's a balancing act of trade-offs.

[jerryfreak]

 i finally found someone at DPA who understands tech questions!

when asked:
1. the various preamps like mmp-a,c,e,g all have different specs for dynamic range. in a given situation is that due to higher noise floor or reduced max SPL?

2. The mmp-e has significantly better performance than the mmp-g. the factory solutions such as DAD6001 and d:vice all power these ‘5V’ mics at less than 3V under load. can performance of MMP-g be improved under higher voltage? we already know from Bruce Meyers suggested circuits that the 406x wants closer to 9V for best performance. conventional wisdom is higher voltage (within spec)= better performance (S/N)


they responded with:
1)      It is the max SPL capability that differs with the various types of amps and thereby reduces the dynamic range (Dynamic Range = Max SPL – Noise Floor).

2)      The MMP-G can in theory give up to 5 dB extra SPL handling by supplying 9 volts instead of the 5 volts.

i want to ask them about the details of idle voltage/load voltage, but i want to make sure i ask the right question. i see inputs often spec'd as 'xx volts over yy resistance'. would this classic 4061 circuit be described as '9V over 10K?'

[Len Moskowitz (Core Sound)]

> i want to ask them about the details of idle voltage/load voltage, but i want to make sure i ask the right question. i see inputs often spec'd as 'xx volts over yy resistance'. would this classic 4061 circuit be described as '9V over 10K?'

That would be 9 Volts through 10k.

I have to caution you about that circuit, because a fresh 9 Volt alkaline battery can provide up to around 9.6 Volts, and a 10k resistor isn't large enough to prevent damage to the 4060-series capsules.

[Gutbucket]

(This will get technical.)

It's not quite correct to think that a capsule's power supply must always stay at a specific voltage. It's a Power supply - meaning a Watt supply - not a Volt supply.

When you see the voltage drop when the capsule is exposed to a loud sound source, what you're seeing is that it's drawing more current across the power supply's (the battery) internal series resistor. (The resistor may function as a current limiting resistor.) That's perfectly fine as long as the power supply can supply enough current, and the resulting under-load voltage is adequate to allow the capsule to capture the sound pressure level without distorting. So the ~2.5V you're measuring might be just fine.

Assuming that your voltage source (the battery again) can provide enough current, selecting the right voltage is an exercise in selecting a voltage that's high enough to allow for high sound pressure levels, and not so high that it will destroy the FET inside that capsule. Equally important is the value of the series resistor. Like much of engineering, it's a balancing act of trade-offs.

Thank you for this explanation, Len.  It clarifies a few things I've wondered about with regards to this for years.

[jerryfreak]

I have to caution you about that circuit, because a fresh 9 Volt alkaline battery can provide up to around 9.6 Volts, and a 10k resistor isn't large enough to prevent damage to the 4060-series capsules.

oh yeah i believe 13K3 was the choice, right?

[jerryfreak]

as an aside, i asked rens heijens about the specs he used for his preamps that include microdot (3/4 of the way down the http://www.rensheijnis.com/DPA.htm page under "Pre-amplifier for standard B&K /DPA Microdot and active powered B&K /DPA microphones") :

he said "I used 15V and a 36KOhm resistor"

that would be the highest voltage ive ever heard to power 406x series

[EmRR]

The diodes are polarity protection I believe.

I've never seen ANY condenser mic measure 48V when connected; same drop under load scenario.  Not a problem.