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Langston

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  1. Too many variables! Way off the WAF chart! Zero hope for your recovery! That last part is a compliment. : ) The easy loudspeaker solution for your situation are high scorers on the Spinorama chart and out from the walls. This would exclude the Klipschorn. I too am new to the Klipschorn and it's a completely different ballgame, though if played correctly will win the World Series against your competitors in a walk. IMNHO. Optimization will require quite a bit of patient study (start with @Chris A 's FAQ's) followed by a divide-and-conquer approach that may frequently challenge what you thought you knew. I'm finding the journey extremely enjoyable, which is necessary or you'll go crazy and/or give up. God bless you and your precious family - Langston
  2. Thanks so much Jim - and sorry for another newbie question, but is it possible to see these papers at the Museum? If so, would it be OK to bring a scanner for the papers of interest and a hard disk for stuff that's been digitized? I'd love to take a week or so to go through everything. I'd also like to get an understanding of the scope involved in "a project to make all available". I'm interested in helping, though I have a feeling I may regret ever typing those words. : ) PWK fascinates me as much as Heyser.
  3. In other news.. I learned something about resistors recently that overstated all my amplifier distortion measurements prior to the modified NC400 post above. I'm seeing a reduction in IMD and THD between about 3dB and 10dB using a new set of well-designed power resistors. The good thing is that my past distortion measurements are, of course, comparable with each other. We all know that resistors increase in value with heating, though some are designed with reduced thermal drift, the better/cheaper way to deal with this is to oversize the resistors and/or provide thermal transfer (cooling). Thermal drift tends to affect all frequencies equally in the audio spectrum and it's gradual and predictable. I accidentally discovered something entirely different recently while trying to buy 200W power resistors from Parts Express to "upgrade" the 100W versions I previously bought. For some reason the 200W version showed much higher IMD and THD readings than the 100W version even at very low levels - less than 1V. I thought something was wrong with the amp at first, but found it was entirely due to the resistor and it's nonlinear distortion derived from something called the Voltage Coefficient of Resistance (VCR). Even the 100W power resistors exhibit significant VCR distortion, but I didn't know it until I spent real money on resistors that act like resistors. VCR apparently is present to a minor degree in most resistors, but particularly in the cheap crap that is so hard to avoid these days. VCR distortion is independent of temperature, varies with frequency and can occur in the millivolt range. This isn't something simple like parasitic inductance or capacitance. It generates IMD and THD and probably other bad actors. I thought you could relax when it came to resistors, but you cannot. I sent the 200W resistors back to Parts Express and got some good ones, ARCOL NHS300 4Ω 1%, through Mouser per the recommendation of the ASR guy (Amir). These things are linear to 2,500V. I should have asked John Siau at Benchmark what he used because that's apparently how the Amir figured it out. I also designed a jig for (4) of these resistors that allows me to switch between 2/4/8Ω without removing cables. Very convenient. : ) God bless you and your precious family - Langston Edit: here's a link to the 1966 paper that Amir referenced. The authors think measurement of the 3rd harmonic distortion component can reveal many of the evils of passive components (L,C,R), though they spend most of the time discussing resistors. I'm always late to the game. : ) Edit 2: here's a link to Bruce Hofer's take on passive component distortion. His math supports the 1966 paper above in that the 3rd harmonic is the tell-tale. So does my experience at this point - keep an eye on the 3rd harmonic and keep the resistors cool and all will be well.
  4. Below are new measurements of my modified NC400 as discussed here. I originally purchased the AHB2 for loudspeaker measurement use due to its amazing specs, sufficient power, convenient size and weight. It didn't have enough power for the loudspeakers I was using at the time, but the Klipschorn changed that. The modified NC400 is better than the AHB2 in every way that matters for measurement use, so it gets that duty now and my Klipschorns get the AHB2. The better specs of the NC400 include more power, equal (and in some cases lower) noise, very similar CMRR and (in some cases lower) distortion, better transfer function with DC coupling, lighter weight, lower output impedance and lower cost. I added a high-current version of the NL4 connector on the back because they are superior and will directly interface with my cabling. BTW, I noticed that the screws on the OEM binding posts that clamp the 12AWG cable from the amp module needed tightening even though I torqued them as much as I dared during the build. Not an ideal design. If you built one of these amps I'd suggest you check on those screws. 120V was used for all measurements. Plenty of room for the NL4. Also plenty of room for additional wires on the amp module screw terminals. Gain and phase response for each measurement. The near zero output impedance results in overlapping gain traces regardless of load impedance. This little amp is a beast. It performs best on the most difficult loads. The following IMD distortion plot is a little busy, but the take-away is that the 1W distortion decreases at higher load impedances as expected, but at 100W and max output (the level required for 1% THD from 10Hz-20kHz) decreases with lower load impedances. This makes me suspect that the input stages are approaching clipping with the higher drive voltages allowed by the higher load impedances. 1W, 100W and max output at 2Ω. (-40dB = 1% THD) 1W, 100W and max output at 4Ω. (-40dB = 1% THD) 1W, 100W and max output at 8Ω. (-40dB = 1% THD) An amazing amp. : ) God bless you and your precious family - Langston
  5. This is a link to a ZIP file with everything I have written by or about Paul Klipsch. About 40MB. I would very much appreciate pointers to anything else you have or know about, thanks! God bless you and your precious family - Langston
  6. I expected the same thing given the Dayton target niche, but I've measured about a dozen Dayton poly caps and found them extremely good, better than some others that are more expensive. I'm talking objective stuff not "sonic differences" between poly caps of the same value, which I've never been able to hear. If you're into soldering, I would upgrade the woofer caps to poly simply because it's inexpensive and they'll never dry out. When it comes to woofers I bet even this upgrade will be inaudible. Michael's a good guy. Must be a communication issue - I do know he's slow on updating their web site (like father, like..), but boy is he fast with shipping (like father, like..). : )
  7. I think that every time Roy posts. Even his terse responses lead one to better understand Klipsch or physics or oneself. He made a joke once about fishing that made two valid points at once, (a) that the poster was spending a great deal of time and effort on something with little reward on the other end, and (b) that the poster was taking himself too seriously. Typical of an engineer - no wasted words. Atypical is his love and respect for his heritage. : )
  8. Exactly - and it makes sense to use the 12V DC output of the Oppo as well to avoid messing with 120V, but either will work assuming the 120V controlling device is a switched outlet (as your amp has per your first post). The relay's sense input works exactly like the 12V trigger system on audio components: it keeps stuff on as long as voltage is present on the sense input and turns off the outlets when that voltage drops below 3V DC or 12V AC. BTW, another (less reliable, but it might work) way to to do this is to use a a power strip that has a "master" receptacle and several "slave" receptacles. If the device on the master receptacle pulls enough current during turn-on and then stops pulling current at turn-off, it'll work. The problem is that many audio components either don't pull enough current at turn-on, or continue to use some current when turned off (standby mode), thus it's hit or miss with these things. God bless you and your precious family - Langston Edit: you'll need something like this to tap off your Oppo's 12V trigger.
  9. My amps and DAC's use a 12V DC trigger circuit that turns them all on or off when operating a single device. Typical and quite convenient. My processor is a professional unit like yours with a rear On/Off switch and I have another gizmo as well that has to be on for the system to work. I found a great solution that ties them into the trigger circuit for $30. This grounded 120V relay has a trigger input that accepts 3V-48V DC and 12V-120V AC, thus you can use your switched outlet to turn On/Off your processor. The relay has (2) outlets that turn stuff on, (1) outlet that turns stuff off (such as lights when you turn on your home theater) and a 4th always on outlet. God bless you and your precious family - Langston
  10. Nice and simple. Haven't seen that before. : ) Another thought is to make sure the big tubes that consume the largest heater currents are closest to the transformer (source) in the heater supply circuit, followed by the lesser current users toward the end of the circuit. This minimizes a potential noise source across the small tubes. The "humdinger" adjustment pot you referred to helped a lot with the Fender Twin, especially after increasing the twist rate of the downstream heater circuit wires. It's been awhile since I've been inside tube amps. Most of my experience was with guitar amps I rented out as backline in concert work. Crazy simple and amazingly reliable stuff. God bless you and your precious family - Langston
  11. Dimensions: 40 miles width 78,000 feet (14.8 miles) height 400 modules identical to the above Casing: Solid Krell Metal 26 inches thick Warranty: Self maintaining Power Supply: 9,200 Thermonuclear reactors Remote control: THE SUBCONSCIOUS ID!! Monitors: Analog meters as God intended! Be warned or die!! As you were - Langston
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