bracurrie
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Posts posted by bracurrie
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So why all the high end sizzle?
The red is no EQ and the green is the result at my amateur efforts to improve things with EQ.Just spoke to the creator and he relates that the paper cones make them "sizzle" with no shouting fatigue. I agree they are smooth and non grating. He also sent me some grill for the Audio Nirvana full rangers. When I can measure I bet that "sizzle" will diminish somewhat.
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I figured out the screen shot steps to show the EQ I am trying.
EQ
23.414 +8.57db Q1.041
311 -5db Q 7.27
2540 -8.38db Q10.13
3333 - 8db Q15.427 -
So why all the high end sizzle?
The red is no EQ and the green is the result at my amateur efforts to improve things with EQ.Not really sure what you mean, but if you mean why it appears to be higher further out I do not know. I have been told not to trust REW above 5k or so.
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Which apogee sound card you running?
Quartet. Its inputs are being used to recieve the REW output from the PC laptop.
Last night I setup my DAC to be the output device on the PC laptop instead of the Alesis sound card which is handling the mic input chores per mark1101 suggestion. This works much better
as the Alesis card kept sending a wee bit of mic signal to its main outputs no matter the settings. Its a cheap card. The image are the results from sweep test from 30 to 12,800 with no EQ measured with mic 3 feet from speaker at the hieght of the fullranger. I believe it confirms that my crossover bi-amp levels are correct. The red is no EQ and the green is the result at my amateur efforts to improve things with EQ.
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Ok, that begs the question - How old is the forum? Does anyone know who's been here the longest?
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For what its worth I did the following when I had a sub. I set it to as high as possible on its crossover which I believe was in the 100 range. I then use the active crossover to send it only signal below 38 because that's where it seemed the Jub cabs rolled off. The sub wasn't doing much but once I had the levels right it seemed to work quite well.
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Make sure the mic inside you laptop is disabled.
Dave
Thanks! I did that at first. Boy was I confused until I go the laptop mic disabled.
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Yep,
I would get soundcard I/O feedback too when I used a soundcard. It always made me question what I was seeing.
I ditched the soundcard. I use a USB cable in to the PC from my mic mixer, and a USB cable out of the PC to my Benchmark DAC. Problem solved.
Great idea. Do you use REW too? Any other tips from your experience? Thanks.
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You guys are too funny, but helpful.It contains all the music ever recorded! LOLI just tried doing sweeps with REW and some real-time with Pink Noise and I am still not sure I am right. Just discovered also that my Alesis IO2 card may have an issue that may be affecting my measurements.
I am using REW on a win laptop connected to the soundcard via USB. The main outs from the soundcard feed to my Apogee soundcard connected to my MAC running Pure Vinyl with RIAA correction turned off ( so the input is passed unaltered). I have a plug-in for EQ and it shows a graph of the music real-time. So anything coming from the measurement mic should 100% go to the win laptop and sweep tones go to the MAC via usb - Alesis - Apogee - usb - mac. Trouble is I am seeing some sound in the EQ window on the MAC that with hand claps and whistles from me show that the signal from the mic is somehow getting to the main outs of the sound card when they aren't supposed to. I guess its a cheap sound card. I need to isolate this issue before I go any further.
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i deserve that.My mic is calibrated for use pointed straight up. Do you think that is a problem?
Only if you don't point it straight up, apparently.
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Its like a business opportunity in a way. Once you have squeezed all the risk out of it, it's too expensive. It's fun to find great value in the land of "4 figure cables". I have taken the chance buying equipment that was less expensive than the recognized best in class and so far I am batting about .750 and I have a tenth the amount in my sound system as compared to some fellows I know. For some reason these same fellows are not eager to listen to my system once I tell them some details.Much to be said for being able to spec precisely what you want for inputs and such, but I guess I am still with Reagan: "Trust, but verify."
I have a company that sources oversees and there is a wide range of quality out there. Sometimes I can pay less and get better quality. Honest testimonials and track records are very good indicators. Price isn't a good predictor on goods made in China.
What I find fascinating is tube manufacturers of today versus NOS or just OS. Just don't have the time to get to the bottom of it. I will have to depend on those that have and are willing to share their expertise.
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I have been told that the switch has to make and break both the positive and ground, which makes sense.I have a few that I plan to use in reverse. But I will check under the hood to make sure I only have switches hooked up and don't get no surprise such as speaker protection.
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My mic is calibrated for use pointed straight up. Do you think that is a problem?I mute all channels except one and measure one at a time with the mic at 3' from the driver pointing right at it. In my case I have a 5 way system, so 10 curves.
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Thanks for the suggestion. Do you position the mic vertically in front of first the full ranger and then the LF twin 15s?I use Pink noise and RTA with mic at 3 ft. to understand each driver performance and adjust from there. I use a referecne pair of speakers to help with final adjustments like what you are doing balancing the gains.
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i think I have found a miles switch that will sense music and make the switch. When I change which amp is getting input music it will be connected to the speakers.
To quote Bruce Smith, All Pro defensive end for the Buffalo Bills "Bad things, Man. Bad things."
Thanks Craig. Yes I do have the ability to turn the incoming signal off when there is no load.Brad,
Be careful with having a music signal pumping into a tube amplifier with no load present it can send them into oscillation especially if the volume is up.
Craig
But to understand further, what happens when a tube amp goes into oscillation?
Your "amp selector" box should put a dummy load on any tube amp output when it is not going to the speakers. Solid State gear is generally more tolerant of no load conditions but to be ultra safe it should have dummy loads also.
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Brad,
Be careful with having a music signal pumping into a tube amplifier with no load present it can send them into oscillation especially if the volume is up.
Craig
Thanks Craig. Yes I do have the ability to turn the incoming signal off when there is no load.
But to understand further, what happens when a tube amp goes into oscillation?
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I am trying to adjust an active crossover setup and I keep going back and forth about 2db on the Audio Nirvana full ranger that is crossed at 200 Hz with 2 15's in a LBAT setup in an open baffle speaker. Dave Harris who made them took a month or more to determine that the best crossover point was 200hz with the LF using 3rd order and the HF using a 1st order. I could use the attenuation he used but I thought it would be fun to see what I get by adjusting the levels.
So do I I use pink noise and a C weighted db meter to set the levels? Or do I need to use tones at a specific frequency to set the levels?
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what I mean and I may not be using the correct vernacular is that the quiet ampsandaound Stereo 15 and the Manley use the same amount of gain from the sound guard to produce equal spl levels. Therefore I believe the Manley to be inherently noisier, in fact I believe the S/N ratio of the Manley to be in the low to mid 80s which would indicate that it's not a gain problem as much as a noisy design or tubes problem.Is that noise difference related to gain differences? I'd be curious about sensitivity comparisons. I recall suspecting the Manley of having had higher gain. What exactly do you mean by at approximately the same gain?
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I'll pass on e-mailing and talking with the remarkable Mr. van Alstine, but I really agree with adjusting parameters to suit. IMO, as you probably've noted, I think high amp gain and problematic gain matching is a major culprit in high audible noise levels.
Jud Barber gladly lowered the sensitivity of my 100-watt OTL amplifiers, which have proved to be very quiet since, once I solved some other causes. His standard sensitivity was 0.5 v. for 100 watts out, which I think is excessive for K-horns. He estimated that he'd lowered the sensitivity to 2.5 volts in for 100 watts out.
I don't know how to translate figures like this to db of amp gain. I gather it's not a simple, linear calculation.
I recall you had some noise issues in your setup. How is it at this time?
Larry, quiter amps did the trick on noise as well as now I am running a full ranger that is not near as efficient as the Faital/Eliptrac horn. Btw my Manley is maybe 10 dB noisier at approximately the same gain as my ampsandsound.com Stereo 15.
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What is the sensitivity (I think that's the term), i.e., what voltage in for 200 watts out?
I don't know and AVA doesn't publish detailed specs. Email them your question and they will answer. Or if you are really patient and tolerant of someone who may be a bit of a curmudgeon you could call and talk to Frank himself. Also, I am not sure of this, but AVA might be willing to adjust the parameters of the amp to suit.
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I don't remember looking at this amp, but it looks very interesting. I like the part of tubes doing what they do best and SS doing what its good at.
http://www.avahifi.com/index.php?option=com_content&view=article&id=108&Itemid=231
Comments and observations by the learned and wise panel?
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my vote is sell your current amp and buy an American designed Emotiva UPA-2, for about $200-225. these rock solid 125 watts will satisfy your ss thirst and could help you spent into the $1k tube amp range. at this price level you should expect to trust the sound and build quality.
my tube vote goes to the American designed and built, Bob Latino sold, VTA ST-120, or with patience and savings, the M-125 monoblocks.
http://dynacotubeaudio.forumotion.com/t396-prototype-125-watt-monoblock-tube-amplifier-kit
This is the second recommendation in this thread for the VTA ST-120. Intriguing.
I know the folks in Franklin TN that do Emotiva. Thier equipment, I have been told by those that repair a wide assortment of gear new and old, is nothing special for the price. I would vote to save your money and go with more money but way more value. I too am intrigued by the VTA ST-120. I would have pulled the trigger on them had I not been bi-amped and not needing tons of wattage.
Food for thought by Frank van Alstine. http://www.avahifi.com/index.php?option=com_content&view=article&id=106&Itemid=231 I have his Synegy 240 SS amp and am really happy. I haven't tried his tube gear, but its bound to good too. For the price I cannot see how you could beat it. The AVA people are also great to work with. American made and American serviced.
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Nothing nicer on a cold night than the warm glow of a tube amp with great music. It's also literally nice to have the heat. On the extreme end, I avoid using my Scott 222c, with its very hot rectifier, when its warm outside as it tends to trigger the AC more often. In the winter it helps keep the furnace from cycling on as often.Took this pic last night in the dark tubes a glowing nice and purtyHas anyone used cooling for tube amps?
as the Alesis card kept sending a wee bit of mic signal to its main outputs no matter the settings. Its a cheap card. 
Tips to adjust levels w active crossovers
in Technical/Restorations
Posted
I am a meathead.
Dave tried his darndest to tell me the full ranger was passed at 400 Hz and I just didn't get it. Well the point finally landed home as he told me about his epic struggle with the 300 Hz bump( see graph above) Well as soon as I figured out how to set the 64 bit software crossover control in Pure Music ( with the help of Rob Robinson at Channel D software) I now have the active configured with the low pass at 200 Hz 3rd order and the high pass at 400 Hz 1st order. Sweet bliss. A glass of wine and a little Miles Davis while the girls watch Grey's Anatomy. 