doctorcilantro Posted March 4, 2005 Share Posted March 4, 2005 Craig & I discussed this once with the Sherwood and I seem to be encountering it again. When my Sunfire (ungrounded) is connected to my PC's audio card via RCA>1/4" cables the volume drops big time in terms of speaker output. the levels stay nice & hot in Wavelab but the speakers take a 10db hit AT LEAST. I was grounded out the + tips of the 1/4" jacks into other components and the PC case is the only one that causes this.... The Sunfire has 3 unbalanced ouputs, one of which is a pre-out (TAPE), and also one set of balanced XLR outs. I am using the Tape so I don't have to crank up the tunes to archive to the PC. The tube tuner seems to take the biggest hit in volume whereas the TT doesn't drop too bad. The cable from the TT to preamp is very short, 1' and the cable from tuner to preamp is about 6ft. I wonder if grounded the Sunfire or ungrounding the PC (not a great idea) it would help. I really know very little about impedance and all that good stuff so I am sitting here scratching my head trying different things. Dr. C Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 4, 2005 Share Posted March 4, 2005 do you have all the volumes on your pc turned up all the way? there should be a main out as well as a wave volume attenuater. Are you coming out of the right output on your sound card? one thing you might consider if you're still having problems is to connect your pc's headphone out into your preamp since that signal runs a bit hotter. btw, what kind of cable are you using? a y-adapter (3 plugs) or a stereo adapter (4 plugs)? Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 4, 2005 Author Share Posted March 4, 2005 The setup: Sunfire Preamp runs to Quicksilver monoblocks; as soon as the TAPE out of the Sunfire is hooked up to PC....volume drops on RF-7's. Emu advised that the I/O impedance on the analog I/O (4 1/4" jacks) is 10K. The Sunfire output impedance is 1.5K I am using a silver core cable that is terminated at one end with RCA's and the other is TRS 1/4" As soon as that TRS is plugged into the Emu soundcard (from Sunfire's TAPE pre-out), the volume drops on the RF-7's. The Sunfire uses a (3) 6922 line stage and a (2) 12AX7 phono stage. I could have sworn the phono took less of a hit than when I was using the tube tuner through the line stage. I can re-test that if it turns out to be a clue. Maybe the Sunfire's line stage 6922's are going? Emu said maybe the Sunfire is putting out at a higher impedance the spec'd. HYe suggested I try connecting the Emu soundcard output to the power amps directly, but I told him I wouldn't be able to discern any drop in volume because I couldn't remove the PC>Stereo connection without losing the experiment all together. Dr. C Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 4, 2005 Share Posted March 4, 2005 Are you absolutely sure your pluggin the preamp into the inputs on your sound card? I once had this problem and was plugging the outs into the in's and so on (does that make sense?). What was really crazy is it still worked but had the same symptom's. Other then something like this your bumming becauses it is definitly a impedence mis-match. I have no problem with my Blueberry preamp and my Audiphile 2496 soundcard combo. I even have 16' cables running to and from the PC. Craig Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 4, 2005 Author Share Posted March 4, 2005 I used to have a 24/96 then a Delta 44, now I've got this EMU 1212M. I should have mentioned this before; the Delta 44 has a breakout box and I got the same symptoms when I pulled the plug in & out of the PCI card that leads to the breakout box. So something was going on with the last card too. I'll double check the connections but I think I had them right. Is 10K to 1.5K a mismatch that would cause this? Dr. C Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 4, 2005 Share Posted March 4, 2005 How are the outputs from the Sunfire isolated from one another? Can you wire up some resistors? Below will give you a zero insertion loss pad, but raise the input impedance to 30k. Values don't have to be exact and it will still work. You'll need one for each channel. If you want a different impedance to feed the Emu card, let me know. IN OUT 0--------R1-----------------------R2------------0 / Zin=30k ohms / Zout=1500 ohms R3 / / / 0 GND R1= 30k R2= 175 R3= 1355 Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 4, 2005 Share Posted March 4, 2005 Instead of two cables with 1/4" TRS and RCA, try using just 1/4" TS (unbalanced). If that doesn't work, then you might need a matching transformer: You'll find more info here: http://www.colomar.com/Shavano/cable_xlr_to_phone.html You can purchase them from radio shack for about $20 a piece and then you will need another adapter to get into RCA (another $3). The reason I suggest the unbalanced 1/4" cable is because there is a chance that the EMU already has the transformer built into it. I noticed that there was a software switch to change between "professional" and "consumer" (balanced and unbalanced....20dBV and 6dBv). I don't know where you might find it though...have you checked your owners manual? Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 4, 2005 Author Share Posted March 4, 2005 Thanks for the schematics. I think there is a little transformer on the Emu. The Sunfire has (3) unbalanced RCA outs. It has (1) XLR out. One of the RCA's is pre-out; the other two are: Mains 1 & Mains 2. There are no 1/4" jacks on the Sunfire. I do not yet have aschematic; if someone does I would pay for the trouble of a copy. When I run any of the unbalanced RCA mains to power amp or tape deck (for headphones), the volume drops as soon as I hook up the Tape Out to the computer OR to the tapedeck's input. What's the deal with this Tape Out. I put the Sunfire Main into the tapedeck's CD Direct Line In and when I hooked up the Sunfire TAPE out to the tapedeck's Tape In ...it gets bogged down just like the PC did with the speakers, etc. Again, how well matched do I need to get. Is the difference from 1.5K to 10K causing a problem or is the answer more complicated than this. Shouldn't the Sunfire Tape Out be able to handle a Tape In without bogging itself down like this; as I imagine they would most likely have similar impedance. Dr. C Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 5, 2005 Author Share Posted March 5, 2005 Now I am confused. The Sunfire manual: The output from your Tape deck connects to the preamplifier's TAPE inputs. These inputs are only selected by using the preamps Tape Monitor switch. The inputs of your Tape deck connect to the preamplifier's TAPE outputs. These outputs are unaffected by the setting of the volume control or the countour controls. BUT: AN external processor can be connected in exactly the same way as a Tape deck - 1. The external processor outputs connect to the preamplifier's Tape inputs. 2. The external processor inputs connect to the preamplifier's Tape outputs. 3. Select the source you would like to listen to, such as CD, and then selct the Tape Monitor switch to listen to the proccessed sound. WTH? Is this a tape loop? Let's say I hook a tape deck as described. If a cd is playing it will combine with the whatever is coming in to the Sunfire via the Tape inputs? If I use my PC in this manner maybe it will eliminate the problem I'm having? I desperately need to learn something about this stuff....may have to switch majors : D Well I just tried setting up the "loop" using the tape deck since I don't enought cables yet to go to the PC. Volume did not seem to cut out. I need to wrap my head around how this "loop" works before I post any further. Dr. C Quote Link to comment Share on other sites More sharing options...
khorn58 Posted March 5, 2005 Share Posted March 5, 2005 Check your gain settings on the EMU patchmix. There are three you can paly with as well as the two in your pc. The patch mix has a two on the input channel and a master out. The Input channel also has a trim insert for more or less gain. Dont forget to check your Pc gain also. Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 5, 2005 Share Posted March 5, 2005 DoctorC, It is a tape loop. The idea , when using the tape monitor switch, is so you can hear the signal as it goes through your tape deck. Great for checking your levels when you have a three head deck. If the signal breaks up, you know you are either overloading the tape deck electronics or the tape itself. Meters can lie. The output impedance of the pre should be smaller than your input impedance to the sound card. If they match, you get max signal transfer, but (here is the unknown) it can really mess with the other pre outs depending on the configuration. My three resistor solution is only meant to more effectively load the preamp tape out. Many amps have a 50k input impedance. Looking at the EMU site, from their specs, your card uses electronically balanced I/O, and is not transformer balanced. Not suprising as it is far less expensive. Marvel Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 5, 2005 Share Posted March 5, 2005 Dr. C I will say this again are you sure your hooking these up correctly. If things are as you state impedance wise you should have no real problem it may drop the volume slightly but it should be hardly noticable if at all. PC OUT goes to Sunfire TAPE IN PC IN goes to Sunfire TAPE OUT Outs to Ins and Ins to Outs sound goofy don't it. If this is the way you have it something is most likely screwed with the tape out of the Sunfire. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 5, 2005 Share Posted March 5, 2005 DP sorry Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 10, 2005 Author Share Posted March 10, 2005 Everything is hooked up A-okay. I was waiting on some cables. The line stage seems to drop in volume more, uese (3) 6922's and I am playing the tube tuner though it. The phono seems to lose less volume. Is this strictly a loss of DB or am I affecting the sound? Possible damage to components? I am under the impression of no damage but high distortion is occuring. Can this be the result of grounding issues? The PC and stereo are hooked up to the same outlet; stereo through line conditioner and PC through mov power strip. How can I check the soundcard's output impedance. Simply put the two wires for the multi-meter in there and read the display? The Emu 1212M is suppoed to have 10K impedance, so if the Sunfire TAPE out has 1.5K I should be golden. Sunfire claims that the TAPE out could handle as low as 600 ohms. Now, hookin up the soundcard's ouputs to the line stage inputs of the Sunfire does not induce the volume drop, it only happens when I finsih connecting the soundcard; by hooking up the TAPE out to the soundcard's inputs. Is there a simple way to see what impedance there is at both ends? Dr. C Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 10, 2005 Author Share Posted March 10, 2005 Thanks for all the help guys. "The selector switch is a "Y". It takes the input source and feeds one copy to the linestage amplifier and one copy to the tape out jack." Does this mean the tube stage is literally bypassed? The TAPE out is handy in that it is a "jumper wire". I can bypass the volume control and record to PC with better SNR and don't have to leave the power amps off. The tuner is a Sherwood S-3000. Mono old tube tuner. I don't have a schematic. I have an old RCA cable that is opened up. I connected it to the TAPE out and then read the resistance on the two center wires and was getting 8.76K with the TAPE out selected on tuner; when I yanked the tuner out of the Sunfire I get 176K I don't really know if this is accurate, I doubt it. When I try the phono section I read about 50K out of the TAPE out. The line inputs of the Sunfire are 50K and the MM phono stage is 47ohm. Are you saying that the TAPE out won't put out the 1.5K ? Rather, it is directly connecting the source to the tape out and thus impedance? I'm in way over my head here. thinking out loud: The quicksilvers and the Sunfire share 1.5K and the volume into the PC from Sunfire TAPE is okay but obviously not loaded correctly if the Sunfire out to Quicksilver >>>RF-7's is getting decreased in volume (overloaded and distorted). Dr. C Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 10, 2005 Share Posted March 10, 2005 Doc, What Mark is saying is when using say a tuner or a CD (basically any high level source) the Input of your PC is directly connected to the source through the Sunfire. So yes the tubes are doing nothing to the signal that is heading to your PC. So if the source can not handle the 10K load of the PC sound card it load the Source down and cuts the single to the Sunfire and then ultimately to the QuickSilvers. The phono section tubes are still in use because they have to apply RIAA curve and amplify the signal to send it out the tape outs so the tube phono stage is acting as a buffer so the phono section is not effected as much. In other words your screwed at least with the old tube tuner. How does this effect CD playback ? It all makes perfect sense to me now that Mark explained it. My Scott LT110B is not effected at all by my PC connected to the tape out of the Blueberry or any other of my 4 High level sources. Craig PS What you might want to try is to use a pair of Y adaptor off each of the sunfires preamp outs and use this signal to record (but you will have to adjust the volume with the Sunfires VC). This will allow you to record all your sources with the tube in the sunfire doing there magic. Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 10, 2005 Author Share Posted March 10, 2005 Thanks for clarifying...I was hoping this would not be the case. I have unbalanced RCA > 1/4" cables going to the sound card from the main outs of the Sunfire. I have to crank the volume way up to get a good signal. Using ASIO I can't affect the input volume with Trim Pots on the Emu software because Wavelab is using ASIO directly. This is unfortunate. But, the phono would be my main recording source. It would also be nice to capture radio. This is starting to taste sour. I was really depending on that TAPE preout but I wanted the tubes on the signal. Even if I devise a resistor circuit as suggested I lose out. I'll have to check again how high the gain has to be on the Sunfire volume control and will record to see if the SNR is good or bad; another obvious downside is with 103db efficient speakers I won't be able to listen through the speakers. Maybe headphones through the TAPE out, but what kind of input impedance does a tapedeck have ( I connect my headphones to this) ? For the record: Sunfire tech support is horrible. I have called three times and cordially inquired as to this unit; fully explaining that I don't know a lot but being very friendly. This guy RXXXX says we'd need all your gear to reproduce the effect when all I want to do is talk about impedence, try to generate some ideas so I can diagnose the issue and find a starting point. It was like pulling teeth; at one point I think he was watching TV and I had to coax him back to the conversation which was rather one sided. I understand he thinks I am a worthless consumer but geez....it was really sad actually. He could have been off the phone in 3 minutes if had been the least bit proactive..."Hey okay have you tried this...it's definitely not that so try this" The funny thing is Sunfire states on their wwebsite that this is how they prefer to handle things, "I quick aside in a phone call can hold the answer that a tech can pick up on". Depressing, I'll shoot them an email. Dr. C Quote Link to comment Share on other sites More sharing options...
doctorcilantro Posted March 10, 2005 Author Share Posted March 10, 2005 LOL I just sold my 750$ Numark digital mixer that had a bazillion outputs/inputs. headphones would be through tapedeck; still no chance? Dr. C Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 11, 2005 Share Posted March 11, 2005 Once you travel on the Ship its a slow slide down until you sink Shoot me a email with your new number we need to chat anyway. Craig Quote Link to comment Share on other sites More sharing options...
maxg Posted March 11, 2005 Share Posted March 11, 2005 Just want to make sure of something here. Are you comparing the volume levels of balanced and unbalanced connections? Typcially balanced connections are 6 dB lounder - could this be the "problem"? Quote Link to comment Share on other sites More sharing options...
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