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Old 27th June 2010, 03:29 AM   #1
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Location: Sacramento
Smile Testing Tube Amplifiers

Hello All.
I have been reinspired. I started this project better than a year ago. I bought a midtower PC case on sale then a hard drive, ram, E-MU 1212 AudioTester 3.0. Then came Pete Millettís interface PCB. The computer is operational today. Petesí interface seems to be working. Lots of hardware, software and cables. I want to test and improve all the amplifiers and speakers I have been designing and building for years.
Now I donít have the first clue how to tie all this stuff together, other than reading a lot and trial & error. I want to stay as ďout of the boxĒ * as possible. To me this is more complex than a Single End Triode amplifier.
Has anyone been down this path with any insights to share?
DT
All just for fun!
*Plug it in and turn it on.
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Old 27th June 2010, 04:34 AM   #2
TheGimp is offline TheGimp  United States
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You might want to read a couple of threads on the trials and tribulations I have gone through getting my distortion measurements to make sense.

I was working on a Single Ended Tetrode (6P1P) amp and having trouble getting readings to make sense:
FireFly Single Ended Tetrode

Vitalstates was working on distortion measurements as well:
harmonic distortion

Here I finally got my distortion measurements to make sense after several people prodded me to straighten up my ground system in the shop.

THD, s/n and IM noisy measurements

Here I finally got my noise floor down and found that UL does not always result in lower distortion:

UL Connection results in higher distortion

Iíll be updating the first link with some recent measurements on tube distortion levels for 6N1P, 6N2P and 6N3P in a day or so.

Tomorrow Iím back to SC again on another road trip (a short 416 mile day).

I hope these help.
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Old 27th June 2010, 02:43 PM   #3
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Thank You TheGimp,
I read much of what you pointed me at in your post. I will reread it when I get that advanced. Now I am sorting the pieces of the puzzle. Petes’ interface card has balanced input and output. I went to Fry’s and bought a PCI E-MU 1212m sound card that sports balanced I’s and O’s. It turns out that this is not just a sound card, it is a sound studio in a box. If you don’t believe it read the box. Breaking this into manageable chunks I printed out chapter 4 of the manual, The PatchMix DSP Mixer. The sound card needs to be configured correctly to output and input. When the sound card setup is complete it can be saved to be used again another time. Off I go to DIY.
DT
All Just for fun!
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Old 27th June 2010, 11:50 PM   #4
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Quote:
I went to Fryís and bought a PCI E-MU 1212m sound card.....It turns out that this is not just a sound card, it is a sound studio in a box......The PatchMix DSP Mixer. The sound card needs to be configured correctly to output and input. When the sound card setup is complete it can be saved to be used again another time. Off I go to DIY.
I have a 1212. For now it is back in the box. Why? I got a deal on an EMU 1820M on Ebay. It resides in this computer where it is used for a "sound studio in a (computer) box". I got the 1820 because it has more channels, mic inputs, External converters, and a phono stage. I have used it to rip some of my vinyl collection to hard disk at 24/96 and much of my CD's have been copied to the hard drive using EAC. I hate to admit it but much of my music gets played right from the computer into a Tubelab SE amp. I even use the 1820 for my phono preamp. I also sold my old Teac 3440 and use this thing for recording now. EMU1820 + Cakewalk Sonar + Quad core PC = Serious recording studio.

I used to have a dedicated PC for measuring amps, but it died. It used an Audiophile 2496 and ran Windows XP, worked great with a clip lead and resistor interface.

I tried using the Mega PC for audio analysis but Patch MIX DSP kept getting in the way. It could have been a Windows Vista problem too. I got a file for Patch Mix DSP off of the internet (EMU web site maybe?) that is supposed to work with Audio Tester, but it would not work with WinAudio MLS which is what I use.

I decided that connecting things that run at 600 volts up to my main PC wasn't such a great idea, so I made a new "second PC". After the previous grief with Patch Mix DSP, I decided to just do what everyone else did, and troll Ebay for a Audiophile 24/192. The PC is functional now, but I have not had the time to build Petes interface.

Good luck with the 1212. Let us know if you get it to work. I still have one, and enough stuff to build another PC.
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Old 28th June 2010, 02:13 AM   #5
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Hello Tubelab and All,
I have chunked off some good sized pieces today. I also cut the sleeves off of my t-shirt and spent some time in the pool. It is 101 degrees F in Sacramento today.
I found that RMAA, RightMark, has worked with E-MU. In the E-MU software there is a pull-down prefabricated template that works with RMAA and fortunately also with AudioTester. I have the sound card outputs looped into the inputs. I have the output graphic attached below. It is a start. Next I will add the Millett Interface.
This dedicated computer is using a OEM version of XP out of a brown envelope. I have the feeling that the E-MU was developed for the XP platform
DT
All Just for Fun!
Attached Files
File Type: doc Doc1.doc (38.0 KB, 35 views)
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Old 29th June 2010, 10:16 PM   #6
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Hello,
I have worked with the E-MU 1212m and the Millett Interface a little more. The sound card output is looped through the MI and back into the input of the sound card. The left trace was a distraction so I turned down the left input to the SC. Things are encouraging but can still use some tweaking. After some refinement I will add information about the E-MU mixer settings including sampling rates. Next is to add a device to test into the chain.
DT
All just for fun
Attached Files
File Type: doc Doc7.doc (36.0 KB, 21 views)
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