I just thought of something. Does the mystery power amp or preamp have little toggle switches to flip for SE vs. Balanced use? You might try exercising them back and forth (with power off) a few times, set them for correct input/output then try things again.
Impedance Mismatch(?) Help
- Thread starter CDLehner
- Start date
jdandy
New member
Chris.......What the heck is the big secret about which preamplifier and amplifier your are having this issue with. Are we playing Jeopardy or trying to help you solve an issue?
CPP
Active member
20, there is only a need for one question and that is What amps and pre-amps are involved.
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CDLehner
New member
- Thread Author
- #28
OK guys...sorry; I wasn't trying to be all Mysterio...or make you play 20 questions, or jump through 20 hoops.
My reasons for withholding the actual models involved were two-fold:
A) I just didn't want to bias the opinions or approach. I wanted to know what numbers were needed, to see if there was a mismatch; give you those numbers...and have you lend a perspective, without what you might personally think about brand ABC or XYZ.
B) I didn't want, to in any way disparage...either piece of gear; because I believe them to both be good performers. Just in this case...the solved issue, not withstanding...I didn't feel they worked well together.
The pre-amp is the Classe CP-700, and I was running it into the ARC VT-50. There...all better?
For the record...I was originally trying out, a C-J ET3-SE/VT-50 combo. No problems. The C-J, of course...only accepts single-ended connections; so I simply stayed SE, and swapped the CP-700 into its place. Now...with SE cables; I might have crossed some things up, as some have suggested. And I had only ever run the CP-700, into the CA-2200; and that was all balanced. So with the "issue"...I went back to balanced, both from the Ayre QB-9 DSD DAC to the CP-700, and CP-700 to the VT-50. No difference; I had the CP-700s volume at 12 o'clock or better, and I could just barely hear a signal. As I said before; I couldn't have crossed XLR cables up(!)...and no, I didn't have the mute button on. And for the record; while it was late...I was sober as a judge
The next day, I just "redid" everything...right down the line; from Aurender, to DAC, to CP-700, to VT-50...and things were "normal" again. I still found the output, to be rather low. At say 12 o'clock...I would call the volume, my relaxing level, lol; but it was nothing like the night previous.
I pulled the CP-700 out, and put a Wyred STP-SE on the VT-50; no problemo...lots of dynamic drive. Then I put the CP-700, back on with his running mate...the CA-2200; sweet.
My theory? The CP-700 has a micro-processor, that does control...input, output, processing, etc (I'm sure those of you, with the 800 have the same...only more). Either I had something there, out of whack (though I still don't think so...because the next day, boom; I had it up and running normally in an instant. Ergo...I am not an idiot
Or...that micro-processor, like ALL computers can sometimes get; was just "stuck" in a "glitch"...and it was restricting volume, or not responding to the right input selection. Etc., etc.
That's the story.
My reasons for withholding the actual models involved were two-fold:
A) I just didn't want to bias the opinions or approach. I wanted to know what numbers were needed, to see if there was a mismatch; give you those numbers...and have you lend a perspective, without what you might personally think about brand ABC or XYZ.
B) I didn't want, to in any way disparage...either piece of gear; because I believe them to both be good performers. Just in this case...the solved issue, not withstanding...I didn't feel they worked well together.
The pre-amp is the Classe CP-700, and I was running it into the ARC VT-50. There...all better?
For the record...I was originally trying out, a C-J ET3-SE/VT-50 combo. No problems. The C-J, of course...only accepts single-ended connections; so I simply stayed SE, and swapped the CP-700 into its place. Now...with SE cables; I might have crossed some things up, as some have suggested. And I had only ever run the CP-700, into the CA-2200; and that was all balanced. So with the "issue"...I went back to balanced, both from the Ayre QB-9 DSD DAC to the CP-700, and CP-700 to the VT-50. No difference; I had the CP-700s volume at 12 o'clock or better, and I could just barely hear a signal. As I said before; I couldn't have crossed XLR cables up(!)...and no, I didn't have the mute button on. And for the record; while it was late...I was sober as a judge
The next day, I just "redid" everything...right down the line; from Aurender, to DAC, to CP-700, to VT-50...and things were "normal" again. I still found the output, to be rather low. At say 12 o'clock...I would call the volume, my relaxing level, lol; but it was nothing like the night previous.
I pulled the CP-700 out, and put a Wyred STP-SE on the VT-50; no problemo...lots of dynamic drive. Then I put the CP-700, back on with his running mate...the CA-2200; sweet.
My theory? The CP-700 has a micro-processor, that does control...input, output, processing, etc (I'm sure those of you, with the 800 have the same...only more). Either I had something there, out of whack (though I still don't think so...because the next day, boom; I had it up and running normally in an instant. Ergo...I am not an idiot
Or...that micro-processor, like ALL computers can sometimes get; was just "stuck" in a "glitch"...and it was restricting volume, or not responding to the right input selection. Etc., etc.
That's the story.
mep
Well-known member
- Joined
- Dec 4, 2013
- Messages
- 5,109
OK...here are the pre-amp output numbers
...and the amp's input numbers
See a potential for "issues"; because it wasn't a very good pairing, IMO.
What you didn't give for your Classe was the output impedance. But since it's SS, it will be very low and there should be no impedance mismatch between it and the ARC amp.
CPP
Active member
Glad you got it all sorted out.
Jack
Active member
Mark
It's not an impedance mismatch, probably something a whole lot simpler.
It's not an impedance mismatch, probably something a whole lot simpler.
Face
New member
OK guys...sorry; I wasn't trying to be all Mysterio...or make you play 20 questions, or jump through 20 hoops.
My reasons for withholding the actual models involved were two-fold:
A) I just didn't want to bias the opinions or approach. I wanted to know what numbers were needed, to see if there was a mismatch; give you those numbers...and have you lend a perspective, without what you might personally think about brand ABC or XYZ.
B) I didn't want, to in any way disparage...either piece of gear; because I believe them to both be good performers. Just in this case...the solved issue, not withstanding...I didn't feel they worked well together.
The pre-amp is the Classe CP-700, and I was running it into the ARC VT-50. There...all better?
For the record...I was originally trying out, a C-J ET3-SE/VT-50 combo. No problems. The C-J, of course...only accepts single-ended connections; so I simply stayed SE, and swapped the CP-700 into its place. Now...with SE cables; I might have crossed some things up, as some have suggested. And I had only ever run the CP-700, into the CA-2200; and that was all balanced. So with the "issue"...I went back to balanced, both from the Ayre QB-9 DSD DAC to the CP-700, and CP-700 to the VT-50. No difference; I had the CP-700s volume at 12 o'clock or better, and I could just barely hear a signal. As I said before; I couldn't have crossed XLR cables up(!)...and no, I didn't have the mute button on. And for the record; while it was late...I was sober as a judge
The next day, I just "redid" everything...right down the line; from Aurender, to DAC, to CP-700, to VT-50...and things were "normal" again. I still found the output, to be rather low. At say 12 o'clock...I would call the volume, my relaxing level, lol; but it was nothing like the night previous.
I pulled the CP-700 out, and put a Wyred STP-SE on the VT-50; no problemo...lots of dynamic drive. Then I put the CP-700, back on with his running mate...the CA-2200; sweet.
My theory? The CP-700 has a micro-processor, that does control...input, output, processing, etc (I'm sure those of you, with the 800 have the same...only more). Either I had something there, out of whack (though I still don't think so...because the next day, boom; I had it up and running normally in an instant. Ergo...I am not an idiot
Or...that micro-processor, like ALL computers can sometimes get; was just "stuck" in a "glitch"...and it was restricting volume, or not responding to the right input selection. Etc., etc.
That's the story.
I have no idea what you've written here, not following your troubleshooting steps. Did you solve the problem or not?
CPP
Active member
The output impedance of the CP-700 per the manual is 100ohms
The input numbers for the VT50 are
[TABLE="class: specifications"]
[TR]
[TH]Input sensitivity[/TH]
[TD]1.95V RMS (Bal or SE) for rated output. (22.8 dB gain into 16 ohms.)[/TD]
[/TR]
[TR]
[TH]Input impedance[/TH]
[TD]200K ohms Balanced, 100K ohms Single-ended[/TD]
[/TR]
[/TABLE]
http://www.arcdb.ws/VT50/VT50.html
blackdog
New member
This is not an impedance mismatch. You're fine there. It is a gain mismatch.
Gain of the VT50 is 22dB. This is actually pretty low for a tube amp. The gain of the Classe is 6dB. The gain of the Conrad Johnson is 25dB (pretty high) so you will typically use less volume control travel with the CJ than you would with the Classe.
There are other factors as well. Efficiency of speakers, size of room, distance from speakers. Even the type/taper of the volume control can make it appear there is a mismatch.
Either the CJ or Classe is compatible with the VT50, from an impedance standpoint.
As to your original problem, I've never heard a Classe have any kind of software glitch that would prevent output. Sorry, but you probably made a mistake in the initial set up somewhere. It happens.
Face
New member
The Wyred 4 Sound STP-SE, which the OP claims works well, only has 6dB of gain as well.
CDLehner
New member
- Thread Author
- #39
Wow...this thread has really turned into a cluster. First of all...it sounds like half the participants, can't even really follow it (or follow links for that matter: post 18...that means 1 page back my man 
). Second...I think I made it pretty clear, I'm no EE; and so maybe my terms were incorrect...by implying "Impedance". But I'm surprised that some of you, didn't get the gist.
I mean, will anyone sit and tell me to my face; some pre-amp/amp combinations, require you to go higher on the volume dial...to get the same output? See...this is why I didn't want to name brands; because it might sound like I'm denigrating either of the pieces involved. I'm not.
The CP-700 is a dynamite piece! It worked lovely with the CA-2200 (and I didn't seem to have any trouble "setting it up correctly" then; nor after I put it back in the second time). But...when I first set it up, with the VT-50 (which is also a lovely piece); I had this "issue". Then...even when I solved the "issue", with that combo; I had to go to like 3 o'clock on the Classe, to get what I consider pretty good, moderately-loud volume.
By contrast, I get to about the same place with the C-J ET3-SE; at about 12 o'clock. Well you say, sure...Blackdog is right; duh...the Classe has only 6db of gain, and the C-J has 25. OK...then why do I only need to go, to about 10 o'clock; to get the same volume with the STP-SE...which Face claims has 6db of gain as well?
Look...I don't really care. Obviously I touched a real nerve...ONCE I NAMED BRANDS; because all the owners and dealers, became indignant that I was somehow knocking their product. I wasn't. Call it gain "mismatch", mistakenly call it Impedance mismatch (though that's what I've always heard, was to blame...when you have too little or too much, volume range); all I know, is I have to really crank the CP-700 with the VT-50...whereas I don't have to really crank the C-J or Wyred, with the VT-50. And I don't have to really crank the CP-700, with the CA-2200. I call that a "mismatch", that's all.
Jeez...you'd think I was the first guy, to ever say "this piece didn't play particularly well, with that piece". Hell...AFAIC; we've built a whole hobby around it.
I have to say; this one surprised and disappointed me Sharks. :S
). Second...I think I made it pretty clear, I'm no EE; and so maybe my terms were incorrect...by implying "Impedance". But I'm surprised that some of you, didn't get the gist.I mean, will anyone sit and tell me to my face; some pre-amp/amp combinations, require you to go higher on the volume dial...to get the same output? See...this is why I didn't want to name brands; because it might sound like I'm denigrating either of the pieces involved. I'm not.
The CP-700 is a dynamite piece! It worked lovely with the CA-2200 (and I didn't seem to have any trouble "setting it up correctly" then; nor after I put it back in the second time
). But...when I first set it up, with the VT-50 (which is also a lovely piece); I had this "issue". Then...even when I solved the "issue", with that combo; I had to go to like 3 o'clock on the Classe, to get what I consider pretty good, moderately-loud volume.By contrast, I get to about the same place with the C-J ET3-SE; at about 12 o'clock. Well you say, sure...Blackdog is right; duh...the Classe has only 6db of gain, and the C-J has 25. OK...then why do I only need to go, to about 10 o'clock; to get the same volume with the STP-SE...which Face claims has 6db of gain as well?
Look...I don't really care. Obviously I touched a real nerve...ONCE I NAMED BRANDS; because all the owners and dealers, became indignant that I was somehow knocking their product. I wasn't. Call it gain "mismatch", mistakenly call it Impedance mismatch (though that's what I've always heard, was to blame...when you have too little or too much, volume range); all I know, is I have to really crank the CP-700 with the VT-50...whereas I don't have to really crank the C-J or Wyred, with the VT-50. And I don't have to really crank the CP-700, with the CA-2200. I call that a "mismatch", that's all.
Jeez...you'd think I was the first guy, to ever say "this piece didn't play particularly well, with that piece". Hell...AFAIC; we've built a whole hobby around it.
I have to say; this one surprised and disappointed me Sharks. :S
CPP
Active member
I just think this was a CP-700 panel assignment error. I found this interesting article about the volume in the CP-700, one highlight that might of occurred in the setup.
"" Among the multitude of options are the ability to set the name, volume offset and
balance setting for each input. If you name an input ‘SSP’, it becomes a unity gain input; in
other words, it bypasses the volume control.
This is useful when integrating a home cinema system into the hi-fi, but dangerous in the
wrong hands.
You can also adjust the rate that the rotary control changes volume, but the standard speed-sensing setting is logical enough – the faster the knob is turned the greater the volume steps. This did catch us out a few times, though; for instance, when the preamp has ‘gone to sleep’ and turned off its display, one way of awakening it is to turn the knob. This can sometimes send it to 0.0 and be a little reluctant to go back up to the 40-50 range .""
http://www.classeaudio.com/reviews/reviews-pdfs/CP700_CAM400-HiFiChoice_May07.pdf
"" Among the multitude of options are the ability to set the name, volume offset and
balance setting for each input. If you name an input ‘SSP’, it becomes a unity gain input; in
other words, it bypasses the volume control.
This is useful when integrating a home cinema system into the hi-fi, but dangerous in the
wrong hands.
You can also adjust the rate that the rotary control changes volume, but the standard speed-sensing setting is logical enough – the faster the knob is turned the greater the volume steps. This did catch us out a few times, though; for instance, when the preamp has ‘gone to sleep’ and turned off its display, one way of awakening it is to turn the knob. This can sometimes send it to 0.0 and be a little reluctant to go back up to the 40-50 range .""
http://www.classeaudio.com/reviews/reviews-pdfs/CP700_CAM400-HiFiChoice_May07.pdf