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Author Topic: Analog gear, patchbays, and signal quality??  (Read 4780 times)

Dan Lawrence

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Analog gear, patchbays, and signal quality??
« on: August 26, 2012, 05:56:11 pm »

In my home studio, I've developed a pretty nice, but small collection of outboard gear. Its grown to the point were its very difficult to make use of it all w/o a patchbay. When I bought some patchbays, it was the only piece of gear I bought from, shall we say, "consumer" grade manufacturers. I wasn't too familiar with the applied techniques using them, so I thought I'd take a chance and see how I liked having 'em around.

I finally redesigned my rack  w/ 48 channels of 4-way, top-access multi-switchable  patches (norm, 1/2 norm, parallel and open, all 1/4 inch TRS style.)  Of course, they are awesome ... in theory, but in reality, a single patch reduced my signal strength by a massive amount. Seems like it was somewhere around 6 or more db. I have two identical patchbays, and found the same results in both. I fear fidelity probably degraded to a similar degree, but strength was enough to make me abandon them. I tried different channels in all switching modes, observing direction of signal flow as outlined on the units.

But, of course, I know no pro studio (w/ racks and racks of analog gear) goes w/out them. So, is it just this low end manufacturer, and like anything you get what you pay for? Or is there some other explanation possible?

I've researched the nicer ones, and I am hoping to achieve studio-quality results w/ "1/4 TRS. Is this impractical? I have a hard time seeing me make the bantam/TT conversion, and would like to avoid open ended wires or soldering on the back side. I'm just growing too much daily, and need flexibility. I also have a couple of grand invested in my cabling, and would hate to redo that expense going to another style. So before I go throw money at other models, I'm hoping to hear what the pros have to say on this topic.

A second question is in regard to directional signal flow. This is specific, yes? It's hard for me to understand, that a TRS connection switch is something other than a straight=through connection. Am I misunderstanding something?

Thanks in advance,
Dan
 
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Rick Sutton

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Re: Analog gear, patchbays, and signal quality??
« Reply #1 on: August 27, 2012, 12:28:29 pm »

 You definitely have something mis-wired. A 6 dB loss is an indicator of losing one leg of a balanced signal. A properly wired patchbay should pass signal with no observable signal loss.
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Patrick Tracy

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Re: Analog gear, patchbays, and signal quality??
« Reply #2 on: August 27, 2012, 01:46:33 pm »

Yep, 6dB sounds like a lifted leg of a balanced connection.

Fletcher

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Re: Analog gear, patchbays, and signal quality??
« Reply #3 on: August 27, 2012, 02:13:36 pm »

Sounds like you need to call someone to look at it... if the 6db loss is full bandwidth then you may very well have a grounding problem.  If the problem starts at 1kHz (ish) and filters out more and more low end as you go down the frequency spectrum -- that is a symptom of a "one legged" connection.

Peace
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

Dan Lawrence

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Re: Analog gear, patchbays, and signal quality??
« Reply #4 on: August 28, 2012, 05:48:33 pm »

I appreciate the input. I'll have to research the possibility that the bays are not for balanced connections. It never occurred to me they might not be. Two bays by the same manufacturer react the same.

Just to clear my head, could any of you comment on this concept of a directional nature to the signal paths?  Does that make any sense?

d
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Dan Lawrence

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Re: Analog gear, patchbays, and signal quality??
« Reply #5 on: August 28, 2012, 06:24:17 pm »

So, that was it. I left behind unbalanced cabling so long ago it didn't occur to me that some bays are made strictly for unbalanced. Boy do I feel silly. But thanks to all for pointing me in the right direction.

Since I will be shopping for new ones, I was wondering if you pros have seen many which were made in this unbalanced style. Because I can't move up to a pro-style TT just yet, I want to be sure to avoid any more mishaps like this. Another feature (I thought) I liked about these units was the easy access switching on the top of the unit. Most others I've seen are either fixed or have internal switches. Is it uncommon to find this easy access switching in TRS models? Can anyone suggest any particular models?

d
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DarinK

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Re: Analog gear, patchbays, and signal quality??
« Reply #6 on: August 28, 2012, 07:30:39 pm »

The Samson S-Patch Plus is actually a surprisingly good piece of gear, despite Samson generally being a bargain brand.  They're durable, and have easy switching on the front panel.  (This means less room for labelling, but for a home studio you'll know where everything is without looking after the first few days, so small labels won't be a problem.)
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Dan Lawrence

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Re: Analog gear, patchbays, and signal quality??
« Reply #7 on: August 30, 2012, 01:06:00 pm »

Thanks for that tip Darin, I'll definitely check those out.

d
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Haolemon

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Re: Analog gear, patchbays, and signal quality??
« Reply #8 on: August 31, 2012, 06:12:04 pm »

The Redco 96 Point TT patch bays seem to be very well designed and made.  I am in the processing of installing a pair now (one for a Great River Mixmaster 20 and one for everything else).

The only trouble with patch bays is that the cables to connect stuff costs as much as the bays themselves.  But I am tired of going around to the back of my setup every time I need to make a change.  :)
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Jim Williams

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Re: Analog gear, patchbays, and signal quality??
« Reply #9 on: September 05, 2012, 11:43:10 am »

Patch bays have always been a compromise. It's convienience vs sound quality. Any patch point will degrade an audio path and it is measurable.

I prefer to not "double patch" audio gear here. That's what happens if you use a bay. You double the patch connections. Each degrades the audio a bit.

Use an Audio Precision analyzer and these problems are easily seen. Bypass switches mounted internally to the gear are another problem point. THD will increase to about .001% just running through a DPDT push switch. Remove it and hard solder those connections and the bypass THD drops to .0002%.

This probably doesn't mean very much for those engaged in producing modern rock/pop, but it is something to deal with if your productions require greater quality and resolution than an MP3.
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Dan Lawrence

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Re: Analog gear, patchbays, and signal quality??
« Reply #10 on: September 05, 2012, 03:49:54 pm »

Jim - I really appreciate that level of input. What your saying seems obvious enough to me, a connected cable being less stable than a straight-through. Add switches to the mix and all the more so. I never had that level of spectrum analyzer, but I do appreciate that someone who does took the time to measure those specs!

Sweet mixing to all!

dd
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Mo Facta

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Re: Analog gear, patchbays, and signal quality??
« Reply #11 on: September 11, 2012, 03:24:25 am »

Yeah, I second the S-Patch's.  I have four of them and they have never let me down in the ten years I've had them.

Cheers :)
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