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Post by simpleman68 on Jun 3, 2017 9:32:00 GMT -5
My DSP has balanced outputs but my amps (Carver 305 monoblocks) are not. (Rig info below)
After using cheapie (Rat Shack) XLR to RCA converters I decided to go with a 1 piece wire (female XLR to male RCA) from Monoprice.
After running the room correction software I got an error message that the left channel was only passing up to 650 Hz and the right was up to ~1500 Hz
Finally put my old adapter back on and realized it was a bad set of adapters.
So I ordered a high quality set of Cardas wires (again female XLR to male RCA) and this time I got up to ~3500 Hz and the room sweep was a failed run.
WTF?!
Why does the cheap Rat Shack adapter work just fine and other wires all over the place with what frequency they pass?
Thanks for any help here, I suspect it's just something obvious I should know but I don't and am stumped.
Scott
Equipment in the chain:
Legacy audio Wavelet
Carver VTA 305M mono blocks
Legacy Whisper speakers
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Post by monkumonku on Jun 3, 2017 9:47:23 GMT -5
My DSP has balanced outputs but my amps (Carver 305 monoblocks) are not. (Rig info below) After using cheapie (Rat Shack) XLR to RCA converters I decided to go with a 1 piece wire (female XLR to male RCA) from Monoprice. After running the room correction software I got an error message that the left channel was only passing up to 650 Hz and the right was up to ~1500 Hz Finally put my old adapter back on and realized it was a bad set of adapters. So I ordered a high quality set of Cardas wires (again female XLR to male RCA) and this time I got up to ~3500 Hz and the room sweep was a failed run. WTF?! Why does the cheap Rat Shack adapter work just fine and other wires all over the place with what frequency they pass? Thanks for any help here, I suspect it's just something obvious I should know but I don't and am stumped. Scott Equipment in the chain: Legacy audio Wavelet Carver VTA 305M mono blocks Legacy Whisper speakers I use an XLR -> RCA adapter for my sub so that cutoff in frequency response wouldn't affect me but I wonder what most applications are for those kind of adapters? If it is for subs that don't have XLR inputs then it wouldn't be noticeable but that seems weird that wiring would affect frequency response like that. |
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Post by novisnick on Jun 3, 2017 9:51:18 GMT -5
Scott,,,,,, because NOBODY gives a RATS ASS!!
Yes, I just couldn't resist!!
Bahahahahahaha
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Post by simpleman68 on Jun 3, 2017 10:23:37 GMT -5
I use an XLR -> RCA adapter for my sub so that cutoff in frequency response wouldn't affect me but I wonder what most applications are for those kind of adapters? If it is for subs that don't have XLR inputs then it wouldn't be noticeable but that seems weird that wiring would affect frequency response like that. Same here; I've never noticed any issues either. I could understand 1 bad batch of wires but why did both sets not pass the full spectrum? For that matter, I'm baffled as to why the spectrum is cut short at all. If anything, I'd expect bad wires to result in noise, open ground issues or to attenuate the entire frequency not just the upper end. Scott |
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Post by simpleman68 on Jun 3, 2017 10:24:17 GMT -5
Scott,,,,,, because NOBODY gives a RATS ASS!! Yes, I just couldn't resist!! Bahahahahahaha Ha! Like Honey Badger. |
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Post by vcautokid on Jun 3, 2017 10:33:25 GMT -5
Adapter should be full bandpass unless otherwise specified. All my adapters at least pass the whole spectrum.
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Post by monkumonku on Jun 3, 2017 10:50:25 GMT -5
I use an XLR -> RCA adapter for my sub so that cutoff in frequency response wouldn't affect me but I wonder what most applications are for those kind of adapters? If it is for subs that don't have XLR inputs then it wouldn't be noticeable but that seems weird that wiring would affect frequency response like that. Same here; I've never noticed any issues either. I could understand 1 bad batch of wires but why did both sets not pass the full spectrum? For that matter, I'm baffled as to why the spectrum is cut short at all. If anything, I'd expect bad wires to result in noise, open ground issues or to attenuate the entire frequency not just the upper end. Scott It's gotta be a conspiracy. Did you check to see if those cables are made in Russia? |
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Post by simpleman68 on Jun 3, 2017 15:22:38 GMT -5
Same here; I've never noticed any issues either. I could understand 1 bad batch of wires but why did both sets not pass the full spectrum? For that matter, I'm baffled as to why the spectrum is cut short at all. If anything, I'd expect bad wires to result in noise, open ground issues or to attenuate the entire frequency not just the upper end. Scott It's gotta be a conspiracy. Did you check to see if those cables are made in Russia? Sounds legit  |
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Post by simpleman68 on Jun 4, 2017 9:02:20 GMT -5
Anybody have a similar problem? What's odd is that this is the 2nd set of adapters that don't work properly yet my $5 Rat Shack ones do.
First Monoprice and now Cardas? Just seems odd that both are flawed.
With the Monoprice wires/adapters, one side was cut off at the 600 Hz mark and the other side was closer to 3kHz.
Scott
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Post by simpleman68 on Jun 5, 2017 17:19:19 GMT -5
An answer! Spoke to Cardas (great folks BTW) and found that the adapter I have from them is hot on pin 3 and after speaking to Legacy Audio, I found my DSP is hot on pin 2. I'm guessing this may happen to somebody down the road and hopefully they'll find this post. I did try to name it with easy to find by search parameters. simpleman has left the building  |
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Post by Casey Leedom on Jun 5, 2017 23:50:09 GMT -5
So you had to solder new connectors then?
Casey
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Post by simpleman68 on Jun 6, 2017 6:51:42 GMT -5
So you had to solder new connectors then? Casey Yes but Cardas will be handling this for me. After speaking with Cardas, they offered to send me a pair that are hot on the correct pin in exchange for this pair for the cost of shipping only. Very nice of them since I ordered this first pair from Audio Advisor.  Scott |
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Post by Casey Leedom on Jun 6, 2017 9:39:09 GMT -5
That's certainly nice of Cardas, but a little disconcerting that there isn't a standard for this ... You'd think that XLR -> RCA would be a fairly standard thing ... Oh well, glad you got it all worked out!
Casey
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Post by simpleman68 on Jun 6, 2017 10:06:21 GMT -5
That's certainly nice of Cardas, but a little disconcerting that there isn't a standard for this ... You'd think that XLR -> RCA would be a fairly standard thing ... Oh well, glad you got it all worked out! Casey Agreed, and this was my first thought after learning there were 2 ways to do the XLR adaptation. A Goog search turned up nothing as well. That was an even bigger surprise. Scott |
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KeithL
Administrator 
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Post by KeithL on Jun 6, 2017 11:07:57 GMT -5
I have to admit that I find this whole thread to be somewhat confusing.... and I suspect that your solution... isn't THE solution.
Most of what was said is in fact quite true.
There are two different standards for XLR connectors - which differ as to which pin is the (+) phase and which is the (-) phase - sometimes referred to as "the US and European standards".
However, if they were reversed in a balanced connection, then the signal would be out of phase.
(If both channels are equally out of phase, then they will still be in-phase with each other, and the net result will be a barely audible failure to maintain "absolute phase".)
It's also true that passive adapters often use only one signal phase from the balanced signal and connect that to the RCA output while simply discarding the other signal.
However, while certain combinations there can result in no sound at all, NONE of them should result in a frequency dependent effect (which is what you described).
Basically, any sort of wiring "mismatch" of this sort should end up giving you either the correct signal, no signal at all, or a signal that is not in correct absolute phase (which is barely audible if at all).
NONE of these possibilities should result in something that acts like a filter... you should either get sound... or not.
Now, some older balanced to unbalanced adapters used a tiny transformer in the adapter.
In fact, in terms of impedance, this is nominally "the best way" to do the conversion.
However, transformers, and especially the cheap ones you find in low cost adapters, have all sorts of flaws which make them a bad idea
(unlike resistors, transformers can actually sound bad in a wide variety of ways).
If your adapters had transformers in them, the it would be quite possible for them to fail to pass things correctly.
(And the possibilities would include odd phase issues that might confuse room correction software.)
However, transformer-based adapters are pretty rare these days.
I also noticed that you didn't mention a few rather pertinent facts:
Did you actually LISTEN to audio through the adapters?
Do they sound really odd, or do they sound perfectly normal, but just seem to confuse your room correction?
I suspect you've got some strange sort of interaction going on between the room correction and your wiring.
Or, more likely, it could be that the Carver amps are introducing some "interesting" sort of phase shift that's confusing your room correction software.
(And the specific characteristics of the wire, including the different capacitance of different brands of cable, could affect that.)
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Post by simpleman68 on Jun 6, 2017 18:58:35 GMT -5
I have to admit that I find this whole thread to be somewhat confusing.... and I suspect that your solution... isn't THE solution. Most of what was said is in fact quite true. There are two different standards for XLR connectors - which differ as to which pin is the (+) phase and which is the (-) phase - sometimes referred to as "the US and European standards". However, if they were reversed in a balanced connection, then the signal would be out of phase. (If both channels are equally out of phase, then they will still be in-phase with each other, and the net result will be a barely audible failure to maintain "absolute phase".) It's also true that passive adapters often use only one signal phase from the balanced signal and connect that to the RCA output while simply discarding the other signal. However, while certain combinations there can result in no sound at all, NONE of them should result in a frequency dependent effect (which is what you described). Basically, any sort of wiring "mismatch" of this sort should end up giving you either the correct signal, no signal at all, or a signal that is not in correct absolute phase (which is barely audible if at all). NONE of these possibilities should result in something that acts like a filter... you should either get sound... or not. Now, some older balanced to unbalanced adapters used a tiny transformer in the adapter. In fact, in terms of impedance, this is nominally "the best way" to do the conversion. However, transformers, and especially the cheap ones you find in low cost adapters, have all sorts of flaws which make them a bad idea (unlike resistors, transformers can actually sound bad in a wide variety of ways). If your adapters had transformers in them, the it would be quite possible for them to fail to pass things correctly. (And the possibilities would include odd phase issues that might confuse room correction software.) However, transformer-based adapters are pretty rare these days. I also noticed that you didn't mention a few rather pertinent facts: Did you actually LISTEN to audio through the adapters? Do they sound really odd, or do they sound perfectly normal, but just seem to confuse your room correction? I suspect you've got some strange sort of interaction going on between the room correction and your wiring. Or, more likely, it could be that the Carver amps are introducing some "interesting" sort of phase shift that's confusing your room correction software. (And the specific characteristics of the wire, including the different capacitance of different brands of cable, could affect that.) Not sure what is going on but I understand what you're saying. That why I was so puzzled.... yes I did listen to music with the old adapters on (after running room correction with good adapters) I swapped in the Cardas ones and it sounds like somebody unplugged the tweeters. It didn't sound like a room correction error although I did get some intermittent buzzing in the tweets an d some odd muffled mids. To clarify, the adapter is connecting the DSP to the Carver amps. The signal sweep was generated from Bohmer audio over the web to the Wavelet and sound was metered via their provided mic which has a calibration file downloaded into the Wavelet. The Legacy Whispers have built in amps that handle everything below 300 Hz so the Carvers are only handling the mids and highs. Maybe I'm misinterpreting the error message? Thanks a bunch for your guidance, it is greatly appreciated. Scott Screen cap  |
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Post by simpleman68 on Jun 21, 2017 11:19:27 GMT -5
Hi Scott, As I said in my meet and greet, I am kind of old school, but I thought I might float a couple of ideas by you. I’m thinking in terms of trying to isolate the problem. If your Wavelet DSP has RCA jacks, you might try just a plain old set of RCA/RCA interconnects and repeat the room correction procedure. But, is it even possible to run the procedure using RCA/RCA with the Wavelet? If so, this might help to settle whether the XLR/RCA setups you have been trying are a part of the problem or not. Any inexpensive set of [low capacitance] RCA/RCA should do fine. Capacitance variations in the interconnects will change the HF rolloff point, but the kind of cutoff you were getting seems almost like a low pass filter action. I am not sure how much interconnect capacitance would contribute to what you are seeing, though it could account for some of the variations. The other thing that caught my attention is that you are running your Carver tube amps into your internally amplified Legacy Whispers, is that correct? If so, there could be some sort of mismatch there, maybe. Have you ever used a different tube amp into the Whispers in the same way as the Carvers except that the Wavelet DSP room correction ran normally? I remember once I took my Dynaco Stereo 35 and tried driving a pair of Martin Logan electrostatics that were internally amplified. The results were a sonic disaster. I am not familiar with the Carver tube amps, but there might be an issue with the load it sees looking into the powered Whispers, I don't know. Do you have another pair of speakers available to you that are not internally amplified? If so, you might try temporarily substituting them for the Whispers and see if the DSP routine will run more normally. Regards, Peter PS – I took a look at the description of the Carver amps www.bobcarvercorp.com/350wattsamps He talks about some sort of room correction that is built into the current version of this amp. Don't know if yours has this feature. If so, perhaps it is interacting with your Wavelet DSP. Again, process of elimination. If you have another amp that you can temporarily substitute for the Carvers, you might check to see if the Wavelet DSP works more normally. My suggestion would be to make one kind of substitution at a time to see if the cause of the problem can be isolated. Thank you for your input. I put an email out to Legacy about the Wavelet and possible interference with the Carvers. To clarify, the Whispers have built in amps that drive the 4 15" drivers and single 12" bass steering drivers. Customer provided amp drives the 4 7" mids, tweet and super tweet. (Cross over is 300 Hz) There is no crossing of signal paths there. Oddly though, my cheapie Rat Shack XLR to RCA adapters work perfectly when running the room correction. Still puzzled as to why the cut off above 3400 Hz. I'll post response from Legacy when I hear back. Just dropped my speakers off to Legacy HQ to have tweet/super tweets upgraded to the new AMT as well as upgraded Cross overs. Scott  |
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KeithL
Administrator
Posts: 10,269
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Post by KeithL on Jun 21, 2017 11:50:58 GMT -5
To be honest with you, given that last piece of information, it sounds like there's simply something seriously wrong with those Cardas adapters. The error message seems to be saying exactly what you're hearing - "there doesn't seem to be much high end". An adapter should NOT do this... and the input impedance of the Carver amps should be a little bit on the high side - which shouldn't cause a proper adapter to do anything weird. Likewise, the output of a solid state DSP unit shouldn't be especially intolerant of slight variations in adapters or cables. (And, if it was some sort of interaction between the Carver amps and your speakers, changing the adapter between the DSP box and the amp shouldn't make any difference.) (It's possible that they grounded the unused input phase in the Cardas adapters, and that the output stage of your DSP thingy really resents it..... in which case you could argue that the adapters aren't "broken" but are instead "wired in a way that makes them incompatible.") Either way, since a passive adapter that isn't broken isn't going to affect the sound in any way.... Just use the cheap Rat Shack ones that work right and call it a day. I have to admit that I find this whole thread to be somewhat confusing.... and I suspect that your solution... isn't THE solution. Most of what was said is in fact quite true. There are two different standards for XLR connectors - which differ as to which pin is the (+) phase and which is the (-) phase - sometimes referred to as "the US and European standards". However, if they were reversed in a balanced connection, then the signal would be out of phase. (If both channels are equally out of phase, then they will still be in-phase with each other, and the net result will be a barely audible failure to maintain "absolute phase".) It's also true that passive adapters often use only one signal phase from the balanced signal and connect that to the RCA output while simply discarding the other signal. However, while certain combinations there can result in no sound at all, NONE of them should result in a frequency dependent effect (which is what you described). Basically, any sort of wiring "mismatch" of this sort should end up giving you either the correct signal, no signal at all, or a signal that is not in correct absolute phase (which is barely audible if at all). NONE of these possibilities should result in something that acts like a filter... you should either get sound... or not. Now, some older balanced to unbalanced adapters used a tiny transformer in the adapter. In fact, in terms of impedance, this is nominally "the best way" to do the conversion. However, transformers, and especially the cheap ones you find in low cost adapters, have all sorts of flaws which make them a bad idea (unlike resistors, transformers can actually sound bad in a wide variety of ways). If your adapters had transformers in them, the it would be quite possible for them to fail to pass things correctly. (And the possibilities would include odd phase issues that might confuse room correction software.) However, transformer-based adapters are pretty rare these days. I also noticed that you didn't mention a few rather pertinent facts: Did you actually LISTEN to audio through the adapters? Do they sound really odd, or do they sound perfectly normal, but just seem to confuse your room correction? I suspect you've got some strange sort of interaction going on between the room correction and your wiring. Or, more likely, it could be that the Carver amps are introducing some "interesting" sort of phase shift that's confusing your room correction software. (And the specific characteristics of the wire, including the different capacitance of different brands of cable, could affect that.) Not sure what is going on but I understand what you're saying. That why I was so puzzled.... yes I did listen to music with the old adapters on (after running room correction with good adapters) I swapped in the Cardas ones and it sounds like somebody unplugged the tweeters. It didn't sound like a room correction error although I did get some intermittent buzzing in the tweets an d some odd muffled mids. To clarify, the adapter is connecting the DSP to the Carver amps. The signal sweep was generated from Bohmer audio over the web to the Wavelet and sound was metered via their provided mic which has a calibration file downloaded into the Wavelet. The Legacy Whispers have built in amps that handle everything below 300 Hz so the Carvers are only handling the mids and highs. Maybe I'm misinterpreting the error message? Thanks a bunch for your guidance, it is greatly appreciated. Scott Screen cap |
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