Tape Loop Replacement Instructions

1. General notes. There are two types of tape echo machines depending on the loop length:
i) Short-Loop Machines with the loop being tight all over its path. These are usually the older style machines, all Dynacord models with the 51cm loop, etc. Use the TL0.51m for the latter.
ii) Long-Loop Machines with the loop being tight only along the part of the path passing the magnetic heads, while the rest of the loop is curled in a separate compartment. Here the total loop length exceeds the geometrical span of the heads for several times, thus reducing the wear of the tape material. These are the renowned Roland RE series machines (RE-150, 201, RE-301, RE-501, SRE-555), and the Korg Stage-Echoes (SE-300, 500). In further text this type of machines will be referred to as the Roland-style machines. Use the TL4m for these units.
With the 4m long loops, approximately 8 times longer tape life is achieved than on the short-loop machines (0.5m loop).

2. The Tape Path. Before removing the old tape carefully investigate its path. Usually it is sketched somewhere on the machine.
It is essential to know the tape path before placing a new loop.
Locate the main rotating shaft (capstan) the black rubber pinch roller (see also §.10 on the other page), and possibly other shafts, leads and tape guides. Going in the direction of the tape movement you should locate the following: an erase head, a recording head, and one or more playback heads. There are exceptions, e.g. RE-301 has the “Sound on Sound” playback head placed just before the erase head. It enables delayed listening and dubbing of sounds with normal loops, or extra long delays with a special short loop.

3. Removing the Old Tape Loop. On the Roland-style machines the tape compartment acrylic cover has to be removed from the tape compartment. Unscrew the necessary nuts. After that the old tape loop can be removed.

4. Cleaning. If the tape loop is replaced without proper cleaning of the unit, an incomplete job is done. Use cotton moistened in at least 96% pure ethanol, or isopropyl alcohol to carefully clean the dirt and Ferro-oxide particles from the heads and all other parts found on the tape path. Don’t scratch the heads with metal or other hard materials. In the case of heavy dirt, repeat the procedure for several times. Clean the bottom of the tape compartment to ensure the minimal friction of the sliding tape. Take some time for alcohol to evaporate.
   If the heads are heavily scratched, or if you can see the grooves made by tape, than the heads should be replaced. Minor damages can be solved by careful polishing. Note that such a delicate action can end up in more harm than good if not done properly! For spare heads contact your local Roland dealers, people who dealt with the reel-to-reel tape recorders (e.g. on old radio stations), etc...
   We don’t have any spare heads or other parts for sale!
   If necessary lubricate the shafts of all rotating and moving parts with fine oil to ensure smooth and even action of the tape transport mechanism. Carefully remove all excessive oil.

5. Optional Demagnetization. If you have a demagnetizer it is advisable to demagnetize the tape echo machine.
The unit must be turned off and no abrupt changes of the magnetic field are allowed, ever! Turn on the demagnetizer far away from the unit and then slowly move it closer. Pass it slowly near the heads and other metal parts for several times, without touching them. Remove the demagnetizer slowly away before turning it off. See also §9 on the next page.

6. Optional Electronic Adjustments. If you have basic electronic skills and the service manual you can consider opening the unit and trimming the recording and reproduction level, the bias frequency and current level. The tapes we use have close setting to the factory ones, so that this procedure can be normally omitted.

7. Opening the New Tape Loops. Remove the whole cover of the plastic packing box to take the loop out. For the TL4m start with the loops which are packed in pairs, to loosen them and ensure more space for the tape. Hold the tape for its edge only. Strictly avoid touching either of its surfaces, especially the magnetic side of the loop with the brown Ferro-oxide layer. For Roland-style machines you don’t have to take the entire loop out of the box, just about 75cm (2ft). Leave the rest in the packing box. If the loop spills out of the box, just hold one of its ends and leave the rest to hang neatly. In either case the rest of the loop will be pulled into the tape compartment when the machine starts.

8. Placing the loop. The brown Ferro-oxide layer must be the inner side of the loop — the side which adheres to the magnetic heads. Thread the tape carefully along its path, around all the guides and over all the heads. On the Roland-style machines, the tape compartment side door must be opened to allow pulling the rest of the loop into the compartment. Now the tape compartment can be covered to prevent the tape from spilling out.

9. Starting the machine. Check the tape position again and start the machine with the lowest speed (on the variable speed machines). On the Roland-style machines take care that the tape outside the compartment does not get stuck as it is pulled in. Check the tape movement along its whole path. If the tape starts to jam, stop the machine immediately! Repeat the procedure from the step 8.
If the tape is placed well, it will run smoothly, adhering tightly to the heads. On the Roland-style machines all the tape should be pulled inside the tape compartment.

10. Testing and finishing. Run the new loop for 5 minutes to soften the material. Verify the mechanical and audio operation of the unit (see more details at the Preservation Tips on the other page). If the tape slows down and jams after replacing the loops, it requires the transport mechanism adjustment. The new tape loop may be thicker and heavier than the old one due to the professional tape used, and may require greater pulling force (see also the §10 on the next page[i] ).
On the short-loop machines, carefully investigate the tape transport. See that the tape path is free of obstacles and that it does not get scratched on the way. Ensure its proper action to avoid stretching and breaking of the loop.

Tape-Echo Machine Preservation Tips

1. Introductory Warning. Most of the tape-echo machines are now 25-30 years old (2006)! For their correct operation the following three vital sections must be in order: 1) the magnetic heads, 2) the tape transport mechanism, 3) the electronics.
General servicing may be needed to achieve the optimum operation quality of these parts and the machine as a whole.
Take care of your old analog tape-echo machine! It is a combination of electro-mechanical and electronic device, comprising an electro-motor, relay, several rotating parts, magnetic heads, etc... During its work the magnetic tape constantly slides against the magnetic heads, guides and leads and wear them over time. Always have this in mind and try to minimize the wear and tear

2. Choice of the Tape. The magnetic tape brands with smooth, the so called lubricated, magnetic surface, must be used for the loops (as are used by Robert L’s Analog Synths).
Never use the “rough tapes” such as AGFA PER-525, some old BASF and other mastering tapes, etc. Although some of these were considered to be the best mastering tapes of all times (due to their excellent adherence to the heads and dense magnetic material), they are inappropriate for the constantly running machines.

3. Never Leave the Machine Turned On Unnecessarily! Turn it off immediately after the usage. If there is a way to stop the tape transport without turning the machine off (e.g. by a footswitch) it's a good idea to do that in every single pause. In this case there is no turn on/off shock for the electronic elements (condensers). This action removes the pinch roller from the motor shaft by releasing the solenoid relay. The motor still runs and the shaft spins, but the tape doesn’t move. As a rule of a thumb, stop the machine this way in each pause lasting more than 2-3 minutes. If the machine must be turned off completely to stop the tape, do that for pauses lasting longer than 5-10 minutes. Too frequent switching on and off is not recommended either.

4. Audio Quality. A correct tape echo machine produces “loud and clear” echoes, with level and quality comparable to the input signal. The infinite loops should be achievable by gaining enough feedback to the recording heads. The full audio spectrum must be present in the first few delays, with the highs rolling off nicely in the later echoes.
Due to the physics of the magnetism the audio quality depends on the tape speed. The higher is the speed, the higher is the audio quality of the reproduced echoing, especially for the higher frequencies.

5. Audio Quality versus Machine Preservation. The higher tape speed also means more wear and tear. Have this in mind when choosing the appropriate combination of heads and tape speed to get the desired repeat ratio. On the units with several playback heads and the variable speed, the same effect can be obtained by choosing a reproduction head closer to the recording head and slower speed, as with a farther away head and greater speed. In the former case the wear of the machine is less, while in the latter the frequency response is better. In other words: if the tape is played with low speed (low “repeat ratio”), the reproduction of high frequencies is inevitably worse than if played with higher speed. The difference may be important in critical uses. Alleviating factor is that the natural high-frequency roll-off is expected and desirable phenomenon, found also in acoustic echoing. A skilled user will utilize this creatively.

6. Bad Sound Quality. The effect signal can be bad for several reasons:
old tape loop, dirty heads and worn-out heads. In all these cases the

symptom will be low volume and signal deterioration in the high audio spectrum. The magnetized heads can cause strange audio interference. Failed electronics causes an extra low signal and severe distortion.

7. Cleaning. The heads and other parts in contact with the tape material get dirty when the machine is used. The heads, tape guides and rollers, together with all other parts on the tape path must be cleaned after every 100-150 hours of use, and even more often in the critical uses like studio recording. Read carefully §4 of the Tape Loop Replacement Instructions.

8. Demagnetization. Echo units which are intensively used and run continuously for long hours tend to get magnetized. All parts made of ferromagnetic metals like steel, chromium, nickel get magnetized. To perform the demagnetization you must have a demagnetizer. An electromagnet can serve the purpose if you are skilled to modify it. The basic procedure of demagnetization is depicted in the §6 of the Tape Loop Replacement Instructions.

9. Tape Loop Replacement. The long tape loops (TL4M) should be replaced after every 500 hours of use, and the short ones (TL0.51m) after 100 hours. In the critical live or studio performances the loop life should be shortened to a half.
The old tape causes deterioration of the audio signal and is the simplest and most common cause of the tape echo low audio performance (see §5). Dropped off material can severely contaminate the machine and greatly accelerate the machine aging process.

10. The Transport Mechanism Adjustment (Roland-style machines). This is needed if the tape slows down, stops and jams because of inadequate tape pulling force. Source of the problem can be a worn-out black-rubber pinch roller which presses against the capstan (the metal shaft rotated by electro-motor), excessive pressure of the leaf spring stabilizer (at the exit of the tape compartment), or a bad position of the electromagnetic relay that is moving the pinch roller. If the problem occurs after the loop replacement, it may be caused by the heavier tape loop. Well adjusted machines (approx. 90-95%) will operate normally even with the heavier loops.*
When the transport is turned on, the pinch roller is pressed against the capstan by the relay. The tape-pulling force may be varied by the position of the pinch roller. Move it toward or away from the shaft holding its axis with your nail. If by doing this the tape transport improves, the problem can be solved by correcting the solenoid position. Contact us for detailed instructions on this.

11. Taking care about the potentiometers. The potentiometers, especially those which are not of the highest quality, are quite wearable parts. Do not use them excessively. Do not use them to constantly produce fade outs/ins, etc... For this purpose, use the potentiometers on other, easier-to-service devices.

12. Rationalizing. The critical and wearable parts on the echo units are magnetic heads, pinch roller and similar. The genuine spares for these are exhausted years ago. Finding adequate substitutes presents a notorious and ever growing problem. Thus the servicing and refurbishing of these units is a complex and difficult task.
Remember the general advice from the beginning: highly rationalize the use of your precious analog tape echoes! Save their unique analog sound for concerts, recordings, and other important occasions. Spare them from situations like prolonged practicing. Do not forget to turn them off when not in use for a long time!