Porta One Hi Speed Upgrade: a.k.a Poor man's 244

L

lo-fi_guy

New member
Well, this afternoon I finally got around to completing my latest project; converting a 1 7/8ips Tascam porta one, into hi-speed 3 3/4ips. Tell ya what, it's like a totally different machine now!!! I put it up against my 244, and the sound quality is basically indistinguishable, no joke, I was actually quite floored! That's why I'm now calling it a "poor man's 244", less the gooey pinch roller-;)

I actually performed this very same thing before on an old Porta two model, it sounded excellent as well. I know they offered a hi-speed version of porta two back in the day, but it's quite rare.

The porta one & two are excellent machines, but I believe they get overlooked due to their lower 1 7/8 speed, which as you know, degrades overall sound quality.

Like I said, both are very simple to covert into a hi-speed models. Infact, The porta one, two and five all share the same deck, as they were lumped into the "ministudio" series.

I thought I'd post this information in the event someone might find it useful. I know the porta one model is quite popular up on ebay. I'm quite sure many folks don't realize that' it's possible to do this upgrade to them.

If anyone is interested how to do the hi-speed conversion, feel free to let me know, I'd be more than happy to share the process with you. I will point out that it does require some soldering skills, and possibly some minor calibration.

ps- I often find valuable info here on HR.com, I figure it's a way to give back if I have the opportunity to do so. Btw, I have 20+ yrs exp in electronics repair, I love tinkering;)
 
Reel,

I will post a pictorial/tutorial for this process showing how it's done for the porta 1 & 2. I'll have it up soon;)
 
In the meantime here's a little info:

I'll start out by saying this mod is totally reversible, just save the old motor!

The stock drive motor in the 1 7/8ips version is 4 lead "single" speed, often Sankyo brand. Sometimes you may find a "no name brand" in there as well. Two of those four wiring leads power the motor, the other two leads are for the pitch control. I'm sure you've may have seen the Tascam HS models, aka hi speed version porta two & porta five. The ONLY major difference is the HS models sport a dual speed motor. The flywheel in the 1 7/8 ips verison is EXACTLY the same as the HS version. As I mentioned before, the old ministudio series all share the same deck.

Therefore, If one were interested in this Hi speed mod, the very first thing they would need to score is a 12 volt dual speed (1600/3200rpm) motor. In truth, they're actually garden variety and can be found in all sorts of cassette based audio equipment. (dual cassette decks for ex:)

In fact, just about all the "modern" Tascam 4 tracks from the mid 1990's onward have "Mabuchi" brand motors in them. I point this out because, this VERY SAME brand of motor is in just about all modern consumer cassette decks.

In short, the motor in a "newer" tascam 4 track is plain old "off the shelf stuff", as it always was... even with the old units. Whatever was cheap and widely available at the time. Therefore, the parts that went into these machines are dime a dozen...

If you like to tinker, you might even have one of these dual speed motors laying around somewhere.

In addition, it MUST be a motor designed for a cassette deck! which looks like:

http://www.negatron.org/wp-content/uploads/2009/02/tascam_motor.jpg

For example: on the Mabuchi brand motor, the data tag will tell you if it's dual speed and it will tell you the rotation. THE MOTOR ROTATION IS VERY IMPORTANT!!! For our tascam mod, it MUST be CW, which stands for "clockwise rotation". This motor in our example picture happens to be CCW, thats stands for " counter clockwise", this rotation will NOT work! As said, you will need to find a CW, or clockwise motor for the ministudio mod to work!


For example: The CORRECT motor you will need for the HS mod will read someting like this:
*12Vdc
*1600/3200 rpm
* 4 lead wiring code on top of the motor will read; - + B A
*CW (rotation)

If you don't have one of these motors laying around, or cannot find one, they can easily be had online for peanuts! Therefore, ANY brand will work just as long as it meets the specs listed above.



PS- When I get those pictures up, it will explain the rest of the process and the addtional steps, as there are a few minor tweaks and other calibrations that need to be done. As I stated before, the porta one and two mods do have a couple different steps to them inorder for them to be modded correctly. For ex: The porta two mod requires a small ceramic disc cap, porta one doesn't. Also, The motor wiring is slightly different on the porta one VS the porta two.
 
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Porta One 1-7/8 IPS to 3-3/4 IPS speed conversion

lo-fi_guy:

I have just purchased a used Porta One in very good condition along with the dual speed motor that you specified for converting the unit from 1-7/8 IPS to 3-3/4 IPS. Per your thread entry below, can you please provide the rest of the conversion instructions?

PS - When I get those pictures up, it will explain the rest of the process and the addtional steps, as there are a few minor tweaks and other calibrations that need to be done. As I stated before, the porta one and two mods do have a couple different steps to them inorder for them to be modded correctly. For ex: The porta two mod requires a small ceramic disc cap, porta one doesn't. Also, The motor wiring is slightly different on the porta one VS the porta two. [/COLOR]Thanks,

Dan
 
Hi, Lo-fi_guy, I also have approx 20+ yrs electronics experience and a Tascam Porta 1 Ministudio and would be interested in knowing that trick, I understand the benifit of the faster tape speed. feel free to e-mail me the how to if you would. Thanks Rick, "Skinny little kid music" use e-mail link above.
 
As long as you are planning on only playing back the tapes on the same machine,increasing the tape speed may be feasable.Nothing in the postings said anything about modifying the record and playback EQ circuits.There are different EQ curves for different tape speeds.Of course, beauty is in the 'ear' of the beholder, and the skewed frequency response may be just what you are looking for.
 
This is really enticing. If anyone can fill in what the OP never followed up on, that would be excellent. In the meantime I’m going to see if my tech knows how to do this. If that’s the case I’ll have him walk me through it. It might not be soon but I’ll do my best.
 
It is a really simple thing to do but increasing the speed on a deck with a soft 4 channel head might not be that great as you will never see that head again. Heads for cassette decks are disappearing quickly. Some great ideas at times end up being bonehead ideas in the end.
 
skywaveTDR said:
It is a really simple thing to do but increasing the speed on a deck with a soft 4 channel head might not be that great as you will never see that head again. Heads for cassette decks are disappearing quickly. Some great ideas at times end up being bonehead ideas in the end.
Click to expand...
That’s potentially true. If the HS model of the PortaTwo used a different head for that reason it would be a good reason to stop right there. If they used the same head I’d be less concerned.
 
They had two heads they used. One wore much longer than the other. The 6008 (end 4 numbers that we refer to them as) was the better head and were use in decks like 234.
 
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