Stax SRM-727 fULL Range High output driver unit ear speaker Instruction Manual

: June 5, 2024
: STAX

Table of Contents

Stax SRM-727 fULL Range High output driver unit ear
To Ensure Safe Use of Your Product
Features
How to use
Preparations
Troubleshooting Notes
Specifications
Attachments
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Stax SRM-727 fULL Range High output driver unit ear

speaker

To Ensure Safe Use of Your Product

illustrations for viewing prior to use.

This manual makes use of various illustrations which have been included to enable you to use your product with complete safety. The situations likely to arise if these illustrations are ignored and the unit is used in the wrong way may be classified as follows. Please read the text and make sure you understand it fully.

Warning: We have shown situations in which ignoring these illustrations and using the unit in the wrong may result in death or serious injury.
Caution: We have shown situations in which ignoring these illustrations and using the unit in the wrong way may result in personal injury and situations in which material damage may arise .

This sign informs you of situations that require precautions (including warnings).
The example on the left indicates precautions against electric shock.
This sign informs you of a prohibited action.
The example on the left indicates prohibition on dismantling.
This sign informs you of an action which must invariably be performed.
The example on the lett indicates removal of the plug from the power socket.

Warning:

Do not take out the power plug or the earpiece speaker plug with wet hands. Doing so may result in electric shock.
Use only the specified power source.
Do not modify, forcibly bend, twist or pull the power cord.
Do not block the radiator vent on the top of the unit.
Do not insert metallic objects, liquids or any other objects into the SRM-7271I driver unit.
Do not touch the ear speaker’s output terminals.
If the unit begins to emit smoke or an odd smell, stop using it immediately and turn off the power.Continued use in such a condition may result in fire and electric shock.It is dangerous to attempt to repair the unit yourself. If the unit needs repairing, always consult your dealer or the Stax service department.
Do not remove the back lid or the cover. Repairs and inspections inside the unit should be entrusted to the store where you purchased the product or to an authorized distributor.
Do not dismantle or modify the unit.

Caution:

Do not put the product in any of the following places. Doing so may result in personal injury or may damage the unit,
A place subject to vibration or shock or on a slope.
A place directly exposed to sunlight.
A place with large amounts of water, moisture or dust.
A place with extreme variations in temperature or close to a source of heat emission (e.g. stove, heater, etc.).
Do not place heavy items on top of the unit. Doing so may unbalance the unit, causing it to tip over or fall down and thus cause personal injury.
Do not drop the unit or submit it to shock of any kind.
Do not raise the volume too high. Listening for a long time at a high volume may result in dam age to your ears. For the sake of your ears and for the sake of the product itselt, we would recommend listening at a moderate volume.

Features

SRM-727l is a power amplifier intended specifically to drive STAX’s electrostatic earspeakers in an ideal method. Furthermore, composed NON-NFB output stage enabled dynamic sound reproducing.
Presence of quadruple volume with outstanding sound quality makes it possible to connect to every kind of line level analog sound output, including XLR connectors.
A selected low-noise dual FET is used on the first stage and the output stage is equipped NON-NFB, large current emitter follower, thereby making it possible to drive the functions of the earspeakers to the full. The coupling capacitor that has an effect on sound quality has been scrapped with a simple configuration DC amplifier, thus realizing a direct and natural sound quality.
In consideration of sound quality and performance, each electronic component employed in the unit has been rigorously selected to ensure that there is as little possible change with time.
SRM-7271l is configured with a balance amplifier using low-noise dual FET, and there is no need for a transformer or an inverting amplifier for XLR balance input.
SRM-727l can invalidate a resource of the volume.
You can use the output of your favorite pre-amplifier and external attenuator. (See Page 5, “How to use the direct switches”)

How to use

Insert the attached power cord into the AC inlet 0 on the rear panel and insert the plug into the power socket.
Connect the device you wish to use for listening purposes into the input terminal 6 on the rear panel.
The input RCA pin jack and the XLR input terminal are operating using the XLR/RCA switch on the rear panel. Note that XLR and RCA cannot be used at the same time. Be sure to detach a cable that is not being used.
The LED 1 will come on if the power switch2 is pushed. Sound can be produced when you hear a clicking noise
Insert the earspeaker you intend to use into the earspeaker power socket on the front panel and adjust to the optimum volume by turning the volume knob@ gradually to the right. The left channel can be adjusted by turning the front of the double knob by itself, while the right channel can be adjusted by turning the back. This makes it possible to adjust the volume balance to left and right.
lf it proves impossible to obtain sufficient playback volume using the REC OUT terminal, connect to the PRE OUT terminal.
Connection methods other than the above: You can listen from a headphone jack using a commercial headphone jack leading to an RCA plug conversion cable, etc.
When using the PRE OUT terminal and a headphone jack, turn up the volume on SRM-7271l to the maximum and adjust the volume with the pre-amplifier or headphone jack volume.

Precautions for use

Take care because the RCA input pin jack and the XLR input terminal cannot be used at the same time. Always remove the cable you are not using.
The unit contains high-voltage parts and is therefore potentially dangerous. Do not use with the top cover or the base plate removed or in places liable to get wet or subject to large quantities of dust or high humidity.
Since the unit emits heat, do not block the vents at the top and bottom of the unit. Do not use the unit on its side.
Because adjustment of sound volume is not possible when passed the built-in volume, please be care ful. See Page 5, “Using the SRM-7271l direct switch”.

Names of parts and examples of connection

How to use the direct switches

At the time of shipment from the factory, SRM-72711 is set using the volume on the main unit.
We will now take a look at how to cancel the internal volume of SRM-727II in order to enable use of the volume of the preramplifier and the external attenuator.

Always follow these procedures before working.

Preparations

Turn off the power switch and remove the power cord from the power socket. Leave for at least 10 minutes in order to prevent electric shock, etc.
Get out the attached hexagonal wrench (see drawing on right).
Remove the screws from four places using the hexagonal wrench in Figure 1.

Caution! While operating, under no circumstances touch parts on P.C.B., inside SRM-727II. Touching such parts may result in electric shock and disturbance of adjustment.

Image from above with the top cover removed:

As shown in the figure below, loosen screws in four places using the attached hexagonal wrench and remove the top
There is a risk of electric shock and of adjustment being disturbed. Do not touch the printed circuit board (P.C.B.) and parts.

Troubleshooting Notes

No Sound:

Is the AC cord properly inserted into the power socket?
Is the power switch on?
Is the LED on the front of the panel on?
Is there anything wrong with the connecting cable?
Has the connected source been selected in the case of the pre-amplifier and the premain amplifier selector switch?

Sound Distortion:

Has the AC power voltage fallen to an abnormal level?
Distortion will arise if the volume is turned up too high.

Imbalance between Left and Right:

Is the input signal normal?
Is the cable connection faulty?
If there is imbalance between left and right, coordinate by adjusting the dual-axis knob.
When the volume is at the minimum level, there may be differences on either side in terms of the position at which the sound actually emerges. There is no cause for this concern since this is not a fault.
If it is not possible to adjust the volume, make sure that the direct switch is to “Direct”.

Humming Noise:

Are the input terminals properly connected? A humming noise may occur if the earth side of the cable is loose.
If a humming noise can be heard, trying connecting the earth of the main unit and the earths, etc., of the other devices.
Is there a faulty connection?
Is the power voltage at the prescribed voltage.
.Humming may be caused because of interference between two or more devices. Is there a device using a large transformer, an electric cooker, etc., in the vicinity? Create more distance between the devices.

If any other symptoms that might be attributable to a defect occur, please consult the dealer or distributor from whom you purchased the device.

Specifications

Frequency properties: DC-115 KHz/ +0,-3 dB SR-007 or SR-404 Signature, when using 1 unit
Rated input level: 200 mV/ 100 V Outputs
Maximum input level: 30 V r.m.s. / at Minimum volume
Amplification: 54 dB (x 500)
Total harmonic distortion: 0.01% /1 KHz, 100 V r.m.s. output SR-007 or SR-404 Signature, when using 1 unit
Input impedance: 50 KR /XLR balance 50K x2
Maximum output voltage: 450 V r.m.s./ 1 KHz
Standard bias voltage: DC 580 VV
Power voltage: 120-240V £5%, 50 to 60 Hz
Power consumption: 46 W
Temperature range for use: 0 to 35C
External dimensions: 195 (w) x 103 (h) x 420 (d) mm(including VR knob and pin jack (20+ 10)
Weight: 5.2 Kg
XLR terminal polarity: No. 1: Sealed; No. 2: Hot; No. 3:Cold (European system)