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Connecting Tascam 38 1/2" reel to Reel to patchbay - he

 
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hallymusic
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PostPosted: Thu Jun 25, 2015 6:36 am    Post subject: Connecting Tascam 38 1/2" reel to Reel to patchbay - he Reply with quote

Hi,
I'm currently trying to setup and configure my patch bays in the studio. I have 2 Tascam 38 machines with unbalanced RCA inputs and outputs.
Should I use an unbalanced patchbay to connect the ins and outs of the tape machines or is it ok to go into a balanced patchbay where the outs and ins are not normaled to each other?

thanks for any help
hally
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A.David.MacKinnon
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PostPosted: Thu Jun 25, 2015 7:40 am    Post subject: Re: Connecting Tascam 38 1/2" reel to Reel to patchbay - he Reply with quote

A balanced bay would work fine. If you're soldering it yourself connect your rca to the tip and sleeve.
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magneticfidelity
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Location: UK/Greece

PostPosted: Wed Jul 01, 2015 9:56 am    Post subject: Re: Connecting Tascam 38 1/2" reel to Reel to patchbay - he Reply with quote

A few consideration must be taken into account for such connections.

What is the rest of the equipment like? Where are you most commonly patching the Tascam machines?

The first question would be if it is a balanced or unbalanced input/output? Balanced I/O's that use transformers for the balancing are fine being connected directly to an unbalanced machine, on the other hand, cheaper equipment, using electronically balanced inputs and outputs are sometimes not happy being directly connected to an unbalanced machine. If you are sure the other machines will accept a direct connection to an unbalanced machine, best practice is to wire the signal or tip of the RCA of the Tascam to the tip of the TRS on the patchbay and connect the earth to both ring and sleeve. Leaving the ring open will result in signal loss in most cases. If you are connecting only to other unbalanced machines, ring connection is not important but it is probably best practice to connect it to ground.

Then you have to consider impedance matching, to avoid distortion and/or signal loss. Finally, you need to carefully consider signal levels. Consumer Hi-Fi equipment usually runs at -10dBV, which means around 0.3 Volts. Standard professional studio equipment usually runs at +4dBu, which means 1.228V. Some prosumer equipment such as those made by Tascam/Fostex were commonly referenced somewhere in between, such as 0.5 or 0.7 V. Some Revox tape machines were putting out 1 V. In some countries, broadcasting equipment was set for +6dBu (1.5 V) and some other countries used to use +8dBu (2 V).

To avoid distortion or excessive noise, all the equipment in your studio should be adjusted or modified to run at the same reference level. When building the Magnetic Fidelity mastering studio we decided for a variety of reasons to use a non standard reference level of +8dBu. We use a variety of equipment, some balanced and some unbalanced. Where ever there was a reference level difference that was too large to sort out by re-adjusting the existing electronics, we used some passive conversion circuits, based on high quality audio transformers, which take care of level and impedance matching. Such units are available from Magnetovolt.
I hope this helps.
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magneticfidelity
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PostPosted: Wed Jul 01, 2015 9:57 am    Post subject: Re: Connecting Tascam 38 1/2" reel to Reel to patchbay - he Reply with quote

A few consideration must be taken into account for such connections.

What is the rest of the equipment like? Where are you most commonly patching the Tascam machines?

The first question would be if it is a balanced or unbalanced input/output? Balanced I/O's that use transformers for the balancing are fine being connected directly to an unbalanced machine, on the other hand, cheaper equipment, using electronically balanced inputs and outputs are sometimes not happy being directly connected to an unbalanced machine. If you are sure the other machines will accept a direct connection to an unbalanced machine, best practice is to wire the signal or tip of the RCA of the Tascam to the tip of the TRS on the patchbay and connect the earth to both ring and sleeve. Leaving the ring open will result in signal loss in most cases. If you are connecting only to other unbalanced machines, ring connection is not important but it is probably best practice to connect it to ground.

Then you have to consider impedance matching, to avoid distortion and/or signal loss. Finally, you need to carefully consider signal levels. Consumer Hi-Fi equipment usually runs at -10dBV, which means around 0.3 Volts. Standard professional studio equipment usually runs at +4dBu, which means 1.228V. Some prosumer equipment such as those made by Tascam/Fostex were commonly referenced somewhere in between, such as 0.5 or 0.7 V. Some Revox tape machines were putting out 1 V. In some countries, broadcasting equipment was set for +6dBu (1.5 V) and some other countries used to use +8dBu (2 V).

To avoid distortion or excessive noise, all the equipment in your studio should be adjusted or modified to run at the same reference level. When building the Magnetic Fidelity mastering studio we decided for a variety of reasons to use a non standard reference level of +8dBu. We use a variety of equipment, some balanced and some unbalanced. Where ever there was a reference level difference that was too large to sort out by re-adjusting the existing electronics, we used some passive conversion circuits, based on high quality audio transformers, which take care of level and impedance matching. Such units are available from Magnetovolt.
I hope this helps.
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magneticfidelity
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PostPosted: Wed Jul 01, 2015 10:03 am    Post subject: Re: Connecting Tascam 38 1/2" reel to Reel to patchbay - he Reply with quote

I forgot to mention that a balanced patchbay can be wired for either balanced or unbalanced operation. Each module can be separately configured. There is not much point in using a patchbay that can only accept unbalanced connections (if they exist), unless you plan on only ever using unbalanced equipment or connections. It might help to consider that very few equipment have a fully balanced internal circuit. Most other equipment only use balanced input and outputs with an unbalanced internal circuit. All equipment can be easily converted between balanced and unbalanced to suit your working environment.
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