Ki Choi Posted February 8, 2007 Share Posted February 8, 2007 Just bought a used Wright WLA 12A preamp that sounds a bit "hotter" than my other tube preamps but very transparent. I liked the way it sounded overall but it also had low 60Hz hum came through the AudioPrism Debut II Silver Signature amp (same as the Red Rose Model 2 Silver Sig) in Triod mode (~18W/ch) driving the Khorns. So I drug out my old oscilloscope and looked at the power from the wall. We live in not so crowded area with very good power (with no fluctuations or spikes although we have few power outages due to trees falling on the main power lines. I used to use P600 and P500 in my system and used to monitor its display on P500 to be rock solid 117V all the time. So, I haven't been able to use P500 with big SS amps and didn't hear much difference with Debut, 8B, Cit IIs, or WM5s so it had been resting in the closet. However, when I looked at the wall power with the scope, I was surprised to see less than perfect sine wave. Its amplitue was somewhat flattened at the top and saw no so smooth wave. The Wright preamp has all tubed retifier section and guessed it would more sensitive to power condition than other gear. Well, I plugged in the PS Audio P500 into the wall and hooked up the scope again... perfect sine wave... The mode choices in the P500s would modify the sine wave a bit and I could hear the noise from the Khorns change in level and frequencies, etc. Let me know what affects the less than perfect sine wave would in sound in general. Here's the before and after photo of the scope screen: Quote Link to comment Share on other sites More sharing options...
Ki Choi Posted February 8, 2007 Author Share Posted February 8, 2007 This is the screen shot of after...P500...no changes to the scope settings. Quote Link to comment Share on other sites More sharing options...
LarryC Posted February 8, 2007 Share Posted February 8, 2007 Let me know what affects the less than perfect sine wave would in sound in general.Interesting -- just like the pics in PS Audio ads. [] I use the smaller P300 to power my turntable, CD player and RTR and cassette decks because I think it makes a real difference with those. It seems like motor-driven components benefit from it. I didn't hear any benefit when I tried it with my preamp, but couldn't play with the S/W frequency because it would change motor speeds. I didn't recognize in your profile what sources you have other than tuners, but I suggest you at least give your CD player or turntable a whirl with P500 power. Quote Link to comment Share on other sites More sharing options...
seti Posted February 8, 2007 Share Posted February 8, 2007 I didn't buy anything super fancy as far as power regulation just an APC computer battery backup power supply featuring ups and avr. I did those mostly to protect against power blinks. If there are other benefits yeehaw. Sorry for venturing off topic here. I have used the WLA12A with SET and now my MC30s. I thought I would sell the wright and buy another preamp when I bought the MC30s but I like the combo so much I will be keeping it. What tubes are you using with your wright? My favorite tube combo now is Sylvania JAN CHS tall chrome dome 6SN7WGT, RCA 6EM7 and Sylvania 6X5WGT. It took me many nights of tube rolling to settle on this combo. Quote Link to comment Share on other sites More sharing options...
efzauner Posted February 8, 2007 Share Posted February 8, 2007 hello What was your scope settings...range, sweep time. attenuation setting How did you connect it to the wall outlets.. What kind of probe did you use. Did you calibrate the probe first. Nice HP scope...I sold lots of those...I still work for Agilent. Quote Link to comment Share on other sites More sharing options...
Ki Choi Posted February 8, 2007 Author Share Posted February 8, 2007 Seti: I hear you... I am probably a bigger skeptic than you are... The fanciest cables in my set up are 15+ year old Monster M1 speaker cables that are mechnically sound with more fliexible construction than I can come up with for the equivant gauge wires... Having EE background in my younger days, it is hard for me to get on the band wagon for the gagets that makes sound of your source better than what it is... OTOH, I do have collection of fancy power cables, interconnects, and speaker cables...that did nothing for me other than look impressive... but then again, I may not be qualifed to hear the differences... However, I have dealt with power as a serious ingrident in having stable operations when I used to design controls for industrial robots that could kill people when it malfunctions due to power situation in factories. Most of the factories I used to visit would have truely dirty power with spikes and fluctuations from the arc welding operations and variable speed AC drives and motors (the variable AC frequency drives use same principle as the PS Audio I believe). The PS Audio devices do work... I am not sure what the true benefits are in terms of sonics. Wright Sound WLA12A (used) came with all different brands of 6SN7 tubes that were all noisy through the Khors. I pulled out a pair of GE NOS 6SN7s I was saving for a future project in restoring a pair of organ amps. It's too early to tell if it sounds any better but certainly quieter than those that were sent to me. I'll have to check the two other tubes. Let me know if you know of a pair of WPA3.5 monos for sale somewhere. For this setup, I am using a Sony SCD-1 as CD source. Efzauner: The scope is a Tektronix....sorry. I do like HP instruments as well. left EE field many years ago so I am a dangerous amature than a competent pro... The scope was set up for 20v/div with a Tektronix 10x probe. I had a ground isolating plug for the scope power and plugged it into the wall outlet. The probe was calibrated by a certified (nuclear...) tech at work few months back and was measuring an AC cord with stripped wires plugged into the wall then moved to one of the conditioned AC outputs of the PS500. I'll have to get back to you with the rest of the settings. Ki Quote Link to comment Share on other sites More sharing options...
efzauner Posted February 8, 2007 Share Posted February 8, 2007 OK on the settings. I just looked so bad that I am scratching my head as to how home power can be that bad.... But once it is rectified and filtered by the capacitors in a power supply....Who cares? The harmonics get rectified too and just add to the DC... In theory , the higher freqeuncy harmonics would filter better anyway since a capacitor in series with the transformer winding resistance and diodes is a low pass filter.. I must be getting blind not to notice the Tek logo.... I personally have an HP 54501 Digital scope on my bench... got it on ebay about 5 years ago for about $400.. what a deal! Automatically measures voltager, RMS Peak, frequency risetime etc etc. Quote Link to comment Share on other sites More sharing options...
Ki Choi Posted February 9, 2007 Author Share Posted February 9, 2007 Digital storage scope would be very nice... Thanks for your insight on how the less than perfect sine wave out of my wall power would be handled by the audio gear. My guess was that if the device has properly designed power supply section, rectified, filtered and regulated DC should be as good as it can get without the help of power regeneration devices such as PS Audio. BTW, I switched the output level switch on the Wright WLA12A to -10db position and the volume is working at around 12 o'clock volume knob with almost no noise with AC power straight from the wall instead of working at ~9 o'clock. Ki Quote Link to comment Share on other sites More sharing options...
JJkizak Posted February 9, 2007 Share Posted February 9, 2007 I don't think I have ever seen power that bad from the power company. JJK Quote Link to comment Share on other sites More sharing options...
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