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Grimm Audio MP1 Manual Manual

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Summary of Contents for Grimm Audio MP1

  • Page 1 Please read this manual before operating the unit!
  • Page 2 TPInLB...

  • Page 3: Table Of Contents

    Table of Contents Introduction Important Safety Instructions 1. Operation 2. Modifying factory settings 3. Specifications 4. Appendix 1, Microphone voltages list 5. Grimm Audio Limited Waranty...

  • Page 4: Introduction

    Introduction Thank you for choosing the Grimm Audio MP1 power supply for tube condensor microphones. The MP1 is eminently fit to be used with modern tube microphones, but it has been especially designed to replace the traditional (usually passive) power supplies that orginally came with the now unique and very costly tube microphones from the fifties and sixties. Contrary to what many believe, these old power supplies can be improved upon, both with regard to stability, noise level and last but not least sound quality. And this is not just because the electrolytics in the old sup- plies tend to dry out, and carbon composite resistors have shot up in value or gone noisy: even if these have been replaced with modern good quality components, the classical supply is still no match for the MP1.

  • Page 5: Important Safety Instructions

    Important Safety Instructions Grimm Audio gaat er van uit dat u deze Engelstalige tekst volledig begrijpt. Als u hier moeite mee heeft dient u contact op te nemen met Grimm Audio. Op verzoek sturen wij u een vertaling toe. Grimm Audio nimmt an, dass Sie diesen Englischen Text völlig verstehen. Wenn notwendig, nehmen Sie bitte Kontakt auf mit Grimm Audio.
  • Page 6 10. Do not use this apparatus near water. 11. Do not use this apparatus outside. 12. Do not expose the apparatus to dripping or splashing. Do not place objects filled with liquids (flower vases, drink cans, coffee cups, etc) on the apparatus. 13. Clean only with a dry, soft, non-fluffy cloth. Do not spray any liquid cleaner onto the cabinet, as this may lead to dangerous shocks. Do not spray any liquid cleaner onto the faceplate, as this may damage the front panel. 14. Install in accordance with the manufacturer’s instructions. 15. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat. Avoid exposure to direct sunlight. 16. Use only attachments or accessories specified by the manufacturer. 17. Use only with a cart, stand, bracket, or table designed for use with professional audio or music equipment. In any installation, make sure that injury or damage will not result from cables pulling on the apparatus and its mounting. If a cart is used, use precaution when moving the cart/apparatus combination to avoid injury from tip-over. 18. This unit runs slightly warm when operated normally. Operate in a normal venti- lated area. If this product will be installed in a rack, make certain there is sufficient air movement within the rack. 19. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as when the power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped. 20. WARNING: To reduce the risk of fire or electric shock, do not expose this appa- ratus to rain or moisture.

  • Page 7: Operation

    1. Operation Upon delivery, an MP1 is factory set to the typical supply voltages of your micro- phone model. This microphone type is indicated at the back of the MP1. If the microphone features remote control of its polar pattern, this can be controlled with the optional knob on the front panel of the MP1. There is a multi-pin XLR cable con- nector supplied with the MP1. You will need to attach this connector to your own microphone cable (or let your dealer do that). For wiring data, refer to the ‘specifica- tions’ chapter of this manual. Please make sure you double check if you soldered the right wire to the right XLR pin, your microphone can get damaged if you fail to do so! In general, we advise to first connect all cables and then turn on the MP1. By doing so one avoids potential damage to the connectors’ plating. It is good to know that due to characteristics of our ‘shunt regulator’ circuitry the peak current is limited, which will lengthen your microphones’ tube life. The MP1 is delivered with a detachable foot. This can be removed by gently twist- ing the foot counter clock wise. Without feet, two MP1’s can be connected together to form a stereo 1U 19” unit. An MP1 generates some heat. When using a stereo set of MP1’s in a 19” rack, it is advised to keep one free rack space below and above to provide optimal cooling. Technology The MP1 features a specially designed discrete shunt high-voltage regulator fed from a current source to maximise suppression from mains induced anomalies. It also offers very low noise (typ. -96 dBV or 16 uV 20-20.000Hz unweighted). More importantly, this shunt supply sounds more natural than the more commonly used modern series regulators, due to the absense of electrolytic capacitors at the out- put. It would have been quick and easy to rely on industry standard voltage regulators for the heater supply. However, in quite a few classical mics the heater voltage is also used to bias the grid of the amplifying tube in the microphone, implicating an open gateway from heater supply to the sensitive input of the mic’s amplifying stage. We therefore chose to design a clean and ultra low noise discrete voltage regulator for the heater supply as well. It features a very low drift to ensure the heater voltage always remains within specs. Both the high-voltage and the heater supplies have an extra ‘crowbar’ protection circuit that will switch on in case one of the supplies breaks down. This is an extra line of defence to protect the valuable tube in your microphone.

  • Page 8: Modifying Factory Settings

    In appendix 1 a list can be found of known microphone types with their factory adviced supply voltages. Should your microphone not be listed, please consult the original manufacturer. Please also check this MP1 manual on Grimm Audio’s web- site, it might have had an update of the microphone list. Three preset high volt- age are available from the MP1: 120, 145 and 210 V. These are set internally using jumpers and not by external controls, to avoid costly mistakes while a microphone is connected. A trimpot allows some (+/-8%) adjustment of these voltages. The HT supply is inherently short-circuit proof as it is a shunt supply. As an extra safety a “crowbar circuit” will shut down the current source in case the output voltage ex- ceeds the nominal value by more than 12% due to malfunctioning. However, Grimm Audio cannot accept liability in case of damage to microphones should even the protection circuit fail. For the heater voltage two preset values are available: 6.0 and 3.9 V. These values are chosen in conjunction to what is prescribed for most classical microphones. They too are set by internal jumpers. A third jumper position enables a trimpot and allows the heater voltage to be set at any desired value between 3.6 and 7.0 V. In addition, the output polarity can be reversed as some mics require negative heater voltage. Noise is very low: typ. < -120 dBV ( < 1 uV), an improvement of at least 30 dB over industry standard voltage regulators. The output is short-circuit proof, the current limits at 0.5 A. As an extra safety a crowbar circuit has been added to protect the mic against unforseen failures should the heater voltage exceed the nominal value by 10% (in case of the variable heater voltage setting a second trim- pot allows the user to set an appropriate threshold). However, Grimm Audio cannot accept liability in case of damage to microphones should even the protection circuit fail. Check the voltages output of your MP1 How the MP1 is set, can easily be measured from the outside: a blue test socket allows the measurement of the heater voltage, a red socket gives acces to the HT divided bij 10 (for safety reasons); a black socket povides a ground reference. These...
  • Page 9 To minimize the risk of accidental damage to microphones equiped with 3.9 V tubes by plugging these into a 6 V MP1 supply, Grimm Audio has decided to deliver its 3.9 V version with an XLR6 socket and the 6 V version with an XLR7 socket. The factory set voltage is indicated on the back. Of course, if a user chooses to change the internal voltage settings, the XLR pin count no longer gives the right indication! This is one of the reasons we disencourage the change of factory settings. The MP1 features a rotary switch to allow a choice of polar pattern on microphones equipped with such a remote control input. The corresponding pin on the XLR6 or XLR7 microphone connector can be varied between 0 V and the 120 or 145 HT volt- ages or between 0 V and HT + 40 V, depending on the internal jumper setting. For example: if HT is set to 120 V, it can be varied between 0 and 120 V or 0 and 160 V. (The 40 V over-voltage is not available at the 210 V setting as there are no micro- phones that require that). Changing the internal settings Opening up the MP1 and changing its internal presets or trimmings is best left to a trained technician. When switched on, there are potentially dangerous voltages as high as 300 V inside. Grimm Audio cannot accept any responsability for damages to either persons, or the MP1 itself, or to any microphone connected by unwittingly chosen voltages or polarities. Before opening the MP1, switch off the mains power and remove the power cord. Also remove any audio cables. Wait 30 seconds to allow the HT on the electrolyt- ics to reach a safe value (< 40 V). Remove the 2 screws from one side of the cover as well as the 2 screw opposite of them on the other side. Carefully slide the cover backwards, away from the wooden front. The electronics will then become visible. An overview of setting and trimpots of the pcb is given in fig.1 on the next page. High Tension (HT) settings Jumpers 7 to 10 set the HT (high voltage to the microphone) to 120, 145 or 210 V. The junper on the left-hand row sets the voltage, the jumper on the right-hand row sets the crowbar protection. They should always be changed in pairs: both in the 120 V position, or both in the 145 V position, or both in the 210 V position. Failure to do so may shut the MP1 down, or incriminate correct protection against over- voltage.
  • Page 10 Fig 1. Voltage adjustment jumpers inside the MP1. In addition, J4 must be set to the upper position when 210 V HT is chosen. (Failure to do so will still output 210 V but the shunt supply will not be able to function op- timally, possibly degrading sound quality). Choose the lower position for J4 if you want a wider range of 0-160 V available for polar pattern control in the 120 V HT case. This will also work for the 145 V HT, resulting in a 0-184 V variable voltage, although no microphone is known to us that needs this setting. The trimpot allows some adjustment of the HT output voltage. The crowbar protec- tion thresholds remain fixed. Trimming the output voltage close to the treshold values is not recommended as this increases the risk of ill-triggered shutdown. To reset a crowbar action it suffices to switch of the MP1, wait a few seconds and switch on again. Heater Voltage Settings The jumpers setting the heater voltage are located to the right in fig.1. First take a look at the two jumpers J2 & J3 in the right-hand top corner. They set the heater voltage’s output polarity: || is positive. Change their orientation by 90 degrees: == is negative. Check with the red (plus) probe of the multimeter inserted into the blue test socket (no mic connected yet!).
  • Page 11 Lower in fig.1 two rows of headers, and two trimpots can be seen. The right-hand row sets the voltages, the left-hand row changes the according crowbar protection levels. Again, the jumpers in both rows must be moved in unison, failure to do so may shut the MP1 down, or incriminate correct protection against over-voltage. Both jumpers are set to the upper position if 6,0 V heater voltage is desired. In the lower position the MP1 delivers 3.9 V heater voltage; the value is intentionally chosen as deviating from the nominal 4.0 V found in the datasheet of the AC701 (+/- 0.2 V is allowed), as many manufacturers specify a slightly lower value for longer tube life or for the subtle change in mic sound reported by some users. However, if long mic cables with thin wires are being used, the voltage at the mic end of the cable may be lower than desired, so if the exact value is considered critical the actual result- ing value should be measured at the microphone itself. Normal tube microphone cables of 10 meter typically show a 0.1 V loss at the microphone. At the factory, the voltages are therefore set to slightly above 6.1 and 4.0 V respectively, which can be measured at the multimeter sockets on the back of the unit. With the jumpers in the mid position both trimpots become active. This allows to set any desired heater voltage between 3.6 and 7.0 V. One can use this for tube mi- crophones with unusual heater voltage requirements, or in case of very long cables to adjust the heater voltage at the microphone to an exact value (e.g. 5.8 V or 3.8 V). The best procedure is as follows. First disconnect the mic cable. Decide what the voltage Vx should be which would set off the crowbar protection (as a rule 10% higher than the desired working voltage). Turn the protection trim (left-hand one) totally anti-clockwise until soft clicks are heard. Switch the MP1 on (no mic connect- ed!). Adjust the right-hand trim until Vx + 10% is reached at the blue test socket; anti-clockwise will increase the voltage. Now slowly turn the protection trim clock- wise until the crowbar steps in: a red led will glow. Back to the voltage trim (R-H) again: do 10 clockwise half-turns (5 full rotations) to lower the setting of Vout. Re- set the MP1 by switching it off, and after a few seconds on again. Now trim Vout to the wanted Vx (do NOT touch the protection trim anymore) and make sure you have set the right HT as well. Switch the MP1 off again, connect the microphone, switch on. If desired measure the heater voltage at the microphone and make further small adustments if necessary. This makes sense for instance if one uses longer cables or cables without a thicker heater wiring. The heater voltage can be adjusted to an exact target value by measuring the voltage in the tube microphone itself. Needless to say this adjustment is better left to a trained technician.

  • Page 12: Specifications

    3. Specifications High Tension voltage: adjustable 120 / 145 / 210 V, with 8% trim. Variable High Tension voltage for remote polar pattern control: HT +0 V / HT +40 V. Heater voltage: adjustable 6.0 / 3.9 / 3.6-7 V Voltages factory preset for microphone type, indicated on the back. 4V heater sup- ply MP1’s are factory shipped with a 6 pin XLR, 6V heater supply MP1’s are factory shipped with a 7 pin XLR. Maximum ambient temperature for operation: 40 °C. Life expectancy power supply electrolytics > 45.000 hours. Power supply voltage range + 6 % /- 10% Fuses: 120 V (USA): fuse 500 mA-T 100 V (Japan): fuse 500 mA-T 230 V (EU): fuse 250 mA-T Weight: 2.3 kg Dimensions: 215 x 175 x 44 mm Power consumption: 20 W Wood type of front: Cherry XLR pinning (of both 6 and 7 pin XLR’s): Pin 1: GND Pin 2: Audio + Pin 3: Audio – Pin 4: Heater Pin 5: High Tension Pin 6: Variable HT (for remote polar pattern control) The XLR audio output is internally hard wired to the corresponding pins of the multi-pin XLR.

  • Page 13: Appendix 1, Microphone Voltages List

    4. Appendix 1, Microphone voltages list AKG C12, C12VR: 120 V & 6.3 V, HT-var +0 V position C24: 120 V & 6.3 V, HT-var +0 V position (this microphone is stereo and needs two power supplies and a cable splitter). (Telefunken) Ela M250, Ela M251, US version: 120 V & 6.3 V (Telefunken) Ela M250, Ela M251, EU version: 120 V & 3.9 V C12a: 120 V & 5.2 V, HT-var +0 V position C28A, C29A, C30A, C60/CK28, C60/CK26: 120 V & 3.9 V: the MP1 cannot be used with these microphones because their output transformer is mounted in the supply. Microtech Gefell CMV563: 120 V & 6 V UM57: 120 V & 6 V, HT-var +0 V position UM92, UM75: 120 V & 5.8 V, HT-var +40 V position M990: 120 V & 5.8 V Neumann (Telefunken) KM(2)53, KM(2)54, KM(2)56, KM(2)64, KM(2)66, M50, M250: 120 V & 3.9 V M49, M249, M269: 120 V & 3.9 V, HT-var +0 V position U67: 210 V & 5.8 V SM69, SM23: 120 V & 3.9 V, HT-var +0 V position (these microphones are stereo and need two power supplies and a cable splitter). U47, U48: the filament supply of these microphones is derived from the HT supply. Please buy our MP47 in stead of the MP1, because it is especially designed for this. M147, M149, M150: these microphones are partly solid state. They need + and -70 V and 32 V and cannot be used with an MP1. Schoeps (Telefunken / Philips / Siemens equivalent) CV60, CM61: 145 V & -5.7 V M200, M201: 150V & -6.3 V M221b: 120 V & 3.9 V M222: the MP1 cannot be used with this microphone because the output circuitry is mounted in its power supply. Sony C37A: the MP1 cannot be used with this microphone because the output transform- er is mounted in its power supply. C800, C800G: These microphones need 276 V which the MP1 cannot deliver. The C800G also needs an additional 6 V for the Peltier element.
  • Page 14 Grimm Audio contact information Grimm Audio CV Strijpsestraat 94 5616 GS Eindhoven The Netherlands +31 (0)40 213 1562 Email: info@grimmaudio.com Website: http://www.grimmaudio.com...

  • Page 15: Grimm Audio Limited Waranty

    5. Grimm Audio Limited Warranty Grimm Audio CV (“Grimm Audio”) warrants this product to be free of defects in ma- terial and workmanship for a period of one (1) year for parts and for a period of one (1) year for labor from the date of original purchase. This warranty is enforcable only by the original retail purchaser and cannot be transferred or assigned. During the warranty period Grimm Audio shall, at its sole and absolute option, either repair or replace free of charge any product that proves to be defective on inspection by Grimm Audio or its authorized service representative. In all cases disputes concerning this warranty shall be resolved as prescribed by law. To obtain warranty service, the purchaser must first call or write Grimm Audio at the address and telephone number printed below to obtain instructions where to send the unit for service. All enquiries must be accompanied by a description of the problem. All authorized returns must be sent to Grimm Audio or an authorized Grimm Audio repair facility postage prepaid, insured and properly packaged. Proof of purchase must be presented in the form of a bill of sale or some other positive proof that the product is within the warranty period. Grimm Audio reserves the right to update any unit returned for repair. Grimm Audio reserves the right to change or improve design of the product at any time without prior notice. This warranty does not cover claims for damage due to abuse, neglect, alteration or attempted repair by unauthorized personnel, and is limited to failures arising dur- ing normal use that are due to defects in material or workmanship in the product. In no event will Grimm Audio be liable for incidental, consequential, indirect or other damages resulting from the breach of any express or implied warranty, in- cluding, among other things, damage to property, damage based on inconvenience or on loss of use of the product, and, to the extent permitted by law, damages for personal injury. © 2011, Grimm Audio CV. All rights reserved Reproduction in whole or in part is prohibited. Specifications subject to change without notice. Grimm Audio MP1 manual v1.0, 11/17/11...