Patchbay signal loss

[NL5]

UGHHHHHHHH!

I just re-wired EVERYTHING to a set of Furman PB40 patchbays. Everything seems to be routing nicely, but I have lost OVER 20db of signal going in and another 20 going out. Anybody have a guess - or can you point me where to start looking for why this is happening?

Thanks in advance.

[SonicAlbert]

So you are saying you lost 40dB on one in/out trip through your patchbays? That's not supposed to happen!

20dB is sort of an odd number, because you'd expect to lose about 14 with a mismatch between +4 and -10. You can lose 6dB by running the wrong kind of cable, like an unbalanced cable between gear that is expecting balanced.

So conceivably you could have a +4 to -10 mismatch and also be running the wrong kind of cable. That could potentially add up to a loss of 20dB.

I see a potential balanced/unbalanced issue going on, with both the patchbay and the cables. Also, the gear on both sides of the patchbay has to be basically set to the same levels, i.e. are you running +4 balanced gear or -10 unbalanced? Or, your patchbays could be weirdly screwed up, although it would be odd to have several of them show the same problem.

I'm really guessing here, because I've never had an experience where I lost that kind of level going through a patchbay. You might want to try and hardwire some of the gear together, just to see if the level problems are indeed caused by the patchbay. Or swap in a different patchbay and see if the units you are using now are the cause. Good old "process of elimination" troubleshooting.

Are your PB40's new or used? I have a stack of Furman PB-48's that I am gradually retiring because they don't seem to be holding up well to even light use, and they don't hold the jacks tight. I'm liking DBX PB48's better, although *any* patchbay of this kind of design is a little suspect and pretty lightweight in the bigger scheme of things.

[NL5]

All the gear was hooked together without a patchbay before withouta problem. I have new "better" cabling - still all balanced though.

[SonicAlbert]

Those PB40's are unbalanced aren't they? Or maybe they accept either balanced or unbalanced, like the Furman PB48's.

Anyway, it sounds like you need to get another patchbay in there and see if you ahve a similar problem with it. Try a DBX PB-48 or one of those inexpensive Neutrik ones.

[NL5]

Nope, they are balanced.......They come in three configs, but mine are balanced - I looked on the cards and I could see the T, R, and Ground.

I am wondering if maybe my new cables are bad..........

[SonicAlbert]

Maybe you should try hardwiring some gear together with the new cables, if you haven't done that already. If you've introduced two new factors at the same time, the cables or the patchbays, the culprit could be either of them.

Patchbays are something I rarely buy used. It's one of those products that just wears out and eventually goes bad with use, especially the 1/4" kind.

It does strike me very odd however that you are apparently having the problem on *all* your connections to the patchbays. Normally, some of the jacks will develop problems while others are fine. So either they are completely shot, or something is drastically wrong with how they are configured, or it could be the cables.

How do you have them configured? Normalled, half-normalled, de-normalled?

[NL5]

Originally Posted by SonicAlbert

How do you have them configured? Normalled, half-normalled, de-normalled?

I believe they are half normaled. The signal runs from the top to the bottom unless a patch is put in the bottom.. All the routing is working, I just get a really low throughput.

[Blue Bear Sound]

Originally Posted by SonicAlbert

20dB is sort of an odd number, because you'd expect to lose about 14 with a mismatch between +4 and -10.

Sorry - no... the difference in signal level between a -10dBV and +4dBu signal is about 12dB (11.82 if I recall)...


But yeah - NL5 - that is a strange problem... if the problem was with the bay, then I would not expect it to be bad on each channel - some would work and others may not (unless the bay was SERIOUSLY defective!)

Follow Sonic Albert's advice on trying the "hardwire" connections with the new cables and no PBs, and see if you get the same results... then try it again with the PB... if everything's fine hardwired, then the problem IS the bay, if not, then gain structure or some other mis-wiring or mis-configuration is the issue.

[NL5]

I can't really hardwire the connections, as all the cables were made for a patchbay. (converters take dsub connecters). I will go and get a trs-trs connector though and try that. I haven't changed any settings on my gear, and it was all working FINE!!!! UGhhhhhhhhhh!

[SonicAlbert]

Good idea, you only need one cable to be able to test every connection.

Do you have a cable tester? I bought one a few years ago and it has been indispensable for troubleshooting. It also has a test tone generator that is very useful for testing connections and levels. It's the EbTech Swizz Army 6 in 1 cable tester.

[easychair]

Originally Posted by SonicAlbert

It's the EbTech Swizz Army 6 in 1 cable tester.

Second thumbs up in one day. Love it.

[NL5]

Well, I got a female trs-female trs connector and bypassed the patchbay - I lost ANOTHER 20+ db - with that I was only able to hit -48 db - with the patchbay -22 is all I can get.



edit - WTF!!! If I run a patch from the top to the bottom on the front, it works fine. I thought the signal was supposed to flow from top to bottom w/o a patch!!!!

[SonicAlbert]

That's how it would work if the patchbay were half normalled. Yours are operating like they are de-normalled.

[NL5]

Hallelujah! Went down to the local GC and talked to someone who actually knew something - although he was as confused as me, and you guys. I went ahead and bought a new Neutrik patchbay, plugged in one channel into the back of it - just as it was set up on the furman, and BAM! - everything is good!

Thanks for all the help!



It was strange that ALL the channels I tried were bad - I don't know about every single one, but I tried 5 outta 20 with the EXACT same results......

[LemonTree]

glad you got it sorted mate. I hate trouble shooting at the best of times.

[c7sus]

Sounds like maybe they installed the cards backwards.

Mondays and Fridays.........

[SonicAlbert]

Originally Posted by c7sus

Sounds like maybe they installed the cards backwards.

Mondays and Fridays.........

Right, or they were de-normalled.

Also, I don't admit to being confused.

You should try taking the cards out of the Furman and move them around to different configurations until you find the one that works. That might save you replacing all of them. The cards probably are in the wrong way for what you want.

Glad you are able to use your studio again now! I'm sure once it's all up and running right you'll find all the patchbays a huge help and give you tons of flexibility. I couldn't do anything with my studio without the patchbays.

[NL5]

Shouldn't they pass NO signal then? I was getting about -22db. Seems like a lot if it were de-normaled or reversed.

[SonicAlbert]

That is odd. Okay, now I'm confused.

[xstatic]

NL5, I just read this thread and I gotta tell ya, it had me nervous. I thought I was going to have some major crap to deal with to make everything right for you. It sounds like you have got it all worked out now though. From what you are describing though, it does sound odd the way things were working out. It doesn't sound like the cards were normalling properly. But yes, completely "denormalled" shouldn't pass any signal in theory.

So everything is all up and working properly now I hope?

[NL5]

Yes, it looks like everything is good. I just bought one bay to see if that was the problem so all I have are my pre's-->converters set-up with one compressor to test everything. I am goingto get two more today(hopefully) and get everything set-up.



Thanks again for all the help.

[SonicAlbert]

I do strongly believe that patchbays are one of those items it is good to buy new, so spending the money on this is a great idea in my opinion. It's good to have something you know is new and working 100%, not only for the signal passing through them but for your own own confidence in your studio as well.

It does sound like your Furman's are configured incorrectly though, at least as far as from what you were expecting. Now that the emergency has passed it might be worth your time to experiment with the card configurations in the Furman's and see if you can get them to work properly.

[NL5]

One last update -

Got the second one installed - all outboard hooked up, went to run a mix thru the Vari-Mu, and only got 1 channel! Ugghhhhh! - the second bay had a bad card, moved it to a different card, and -- - - - - - NIRVANA!

(gotta love the V-Mu)

[SonicAlbert]

One thing I *will* buy used is a patchbay or two to cannibalize for spare cards. You can sometimes grab a compatible patchbay really cheap and even if it has some bad card it will most likely have more good ones, which you can use to replace any that are bad in your other patchbays.

I bught a Manley Vari-Mu a while back but it didn't really do it for me, on my music at least. I could see it being absolutely great for some things though. So I sold it.

However, would *highly* recommend you have the T-bar mod done, it makes it sound even better, richer and smoother.

[NL5]

Originally Posted by SonicAlbert

I bught a Manley Vari-Mu a while back but it didn't really do it for me, on my music at least. I could see it being absolutely great for some things though. So I sold it.

A lot of people love the Vari-Mu, many don't. I like it on the two buss with just a couple db reduction. It really gels things together and adds just a hint of "warmth" and "fatness". It was fun last night watching my wife try and hear it when I'd switch it from bypass to in. I had it set to where there was almost no volume gain, so the effect was subtle, but definetly there.

Anyway, thanks again for the help!