Otari MTR15 Fan Noise

[RoadDawgWest]

Curious if other members here might have experience with an Otari MTR15 tape machine. Technically there is nothing wrong with the machine, but it has a cooling fan. When listening to music such as Jazz it is not much of a bother, but when listening to solo piano tapes for example you can hear a high frequency sound from the on board fan. The machine is 7-8 feet from the listening position, and I have been using a wool blanket around the bottom to lower the noise.



Moving the machine out of the room or further away is not an option. I'm OK with leaving the wool blanket, but it is rather unsightly.
I suspect studios had to deal with this in the past. Open to any suggestions, or ideas.

[kcin]

I've not had experience with this machine- but have had a lot of experience with drive motors in other electrical-mechanical devices. Usually crud or dried out lubricants causing binding or worse case bearing wear. Wait for experts on this piece to chime in but sometimes a drop of light machine oil will solve those kinds of issues. It may not hurt to examine the unit and the fan pathway for dust causing these issues - clean or vacuum as necessary.


In the meantime, you should sell me your Technics unit as that impressive Otari is taking up a lot of space.

[MylesBAstor]

I will be selling a Technics machine soon.

[RoadDawgWest]

Thank you kcin
I have gone over the machine, cleaning, applied new grease, and lubricants. The transport is smooth, and silent. The fan is clean, but has the high frequency whining noise. I have no previous reference to compare the noise, but it does not sound like anything is wrong. I believe it is normal.

The Technics 1500 was my fathers, and has been in my family since it was purchased new. A few years ago I had j-corder tune it up. The original head where like new, but I decided to also purchase a separate JRF head block wired for direct out. It would be very difficult for me to part with that machine, for sentimental reasons.

[jonathanhorwich]

Email me and I'll get you a solution for the fan noise. Jonathan Horwich

[RoadDawgWest]

Thank you Jonathan.

[Ki Choi]

I cannot tell a lie... I have four Otari MTR-15s in the house. Now that I got that confession out of my chest,...

Unlike the Sony APR machines (especially the later models with "improved" fan for cooling the cramped power supply that sounds like an airplane taking off) with unbearably loud fan that is not audiophile friendly at all, I have not noticed any fan noises from the Otari MTR-15s.

The fan in MTR-15 is for the card cage (DC Fan AS1040) cooling with less demand. The 24VDC coil fan is running slower than it is supposed to for lower noise with 20VDC power supplied from ambient air cooled power supply section with heatsink fins in the back of the machine.

If you are hearing the fan noise, the bearing in the fan may be bad and you are hearing high pitch bearing noise. One quick fix is to replace the fan with a new one with same specs. Or if it still bothers you, you can modify the fan operation: You can do this by replacing the current fan with one that has twice as much airflow capacity and run it at half voltage. You can get commercially available "silent" fans made for gaming PC's that runs at 12VDC and source the power from non-audio related section such as the VU meter lamp power supply that is generally at 5.6VDC or so. You will cool the card cage with same amount of original airflow requirement but the fan is running at far slower speed while generating min noise.

MTR-15 is one of the most advanced master tape recorders with such neat feature as auto record bias that none of the Studers have... But similar to the Sony APR machines, MTR-15s don't get much respect from the community. So sad...

[MylesBAstor]

Soren moved the PS outboard for Harry Weisfeld's Sony deck. Dead silent. And sounds great stock.

[RoadDawgWest]

I cannot tell a lie... I have four Otari MTR-15s in the house. Now that I got that confession out of my chest,...

Unlike the Sony APR machines (especially the later models with "improved" fan for cooling the cramped power supply that sounds like an airplane taking off) with unbearably loud fan that is not audiophile friendly at all, I have not noticed any fan noises from the Otari MTR-15s.

The fan in MTR-15 is for the card cage (DC Fan AS1040) cooling with less demand. The 24VDC coil fan is running slower than it is supposed to for lower noise with 20VDC power supplied from ambient air cooled power supply section with heatsink fins in the back of the machine.

If you are hearing the fan noise, the bearing in the fan may be bad and you are hearing high pitch bearing noise. One quick fix is to replace the fan with a new one with same specs. Or if it still bothers you, you can modify the fan operation: You can do this by replacing the current fan with one that has twice as much airflow capacity and run it at half voltage. You can get commercially available "silent" fans made for gaming PC's that runs at 12VDC and source the power from non-audio related section such as the VU meter lamp power supply that is generally at 5.6VDC or so. You will cool the card cage with same amount of original airflow requirement but the fan is running at far slower speed while generating min noise.

MTR-15 is one of the most advanced master tape recorders with such neat feature as auto record bias that none of the Studers have... But similar to the Sony APR machines, MTR-15s don't get much respect from the community. So sad...

Ki Thank you for the response.
Wow! Four MTR15's. I would like to add another one, but will wait for the machine to find me versus me searching for another machine.
I believe what I am hearing is high pitch bearing noise.

The following is a video clip from YouTube (not my machine), and exhibits the noise I'm hearing. After the person turns on the machine (at 6-seconds into the clip) you will hear a low frequency spin up to steady high frequency.

Not sure if the noise is normal fan noise, and simply replacing the fan will resolve the issue. As you stated above I suspect I will need to source a fan that can produce double the airflow, and half the voltage.

I can see the fan from inside the card cage, but after removing bottom panel that access the rear of the card cade I discovered it is not easy to access the fan. I will take sometime over the weekend to look over the exploded views in the maintenance manual to determine the best way to access the fan. If you have any experience to share on how to access the fan, that would also be appreciated.

Thank you for the help
Don