This amp being a balanced topology has inherently great PSRR and 1mV ripple PSU is not needed. I like the SLB but I also like simplicity. The SLB was designed for 5A and 6A is just over the limit. I felt using two SLBs was just too much complexity as the amp has a lot of parts internally. I wanted to free you some room and reduce complexity.
I have some pre-production samples coming my way for some final XO tweaks and adjustments. These speakers have the custom CNC waveguide for the tweeters, and a beautiful rosewood veneer cabinet with solid copper Viborg binding posts. Crossover will use nice custom made MKP caps and heavy gauge inductors.
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On the bench was the SuSyLu and more FFT measurements with a different analyzer. I think the Focusrite is damaged as noise was high. Switched to an inexpensive Behringer UM-2. Works well enough for this application as long as you don’t need to go less than 0.001%THD.
SuSyLu Where Are You?
A couple of good findings:
1. Amp displays dominant second harmonic distortion profile up to about 28w. About that the third harmonic starts to get higher. Higher order harmonics are all monotonously descending and at lower powers there is not much above 4th or 5th harmonic. All this is consistent with typical SE Class A amp behavior. Predictions show dominant third harmonic but that assumes perfect balance on both legs, rarely achieved in reality on a big discrete amp like this. So this is a fortuitous result and I’ll take it.
2. At max power of 100w, the measured THD is 1.4% and this is consistent with prediction that THD would be 1.47% is good and shows that the model is not too far off. It also means that for the majority of music played at or below 25wrms level, the dynamic peaks up to 6dB more will still have a nice harmonic profile.
3. The 60Hz mains peak is very low and the (2f) mains peak at 120Hz is only -95dB below peak signal. A very good result for a linear CRCRC PSU. Consistent with the Fluke 101 measurement of 0.2mV rms.
4. The noise floor baseline is also very good at -125dB and there is little noise in the higher frequency band above 1kHz. This should make for a very silent black background for music playback.
This is 8w:
This is 28w:
This is the noise background with no signal:
SuSyLu Where Are You?
A couple of good findings:
1. Amp displays dominant second harmonic distortion profile up to about 28w. About that the third harmonic starts to get higher. Higher order harmonics are all monotonously descending and at lower powers there is not much above 4th or 5th harmonic. All this is consistent with typical SE Class A amp behavior. Predictions show dominant third harmonic but that assumes perfect balance on both legs, rarely achieved in reality on a big discrete amp like this. So this is a fortuitous result and I’ll take it.
2. At max power of 100w, the measured THD is 1.4% and this is consistent with prediction that THD would be 1.47% is good and shows that the model is not too far off. It also means that for the majority of music played at or below 25wrms level, the dynamic peaks up to 6dB more will still have a nice harmonic profile.
3. The 60Hz mains peak is very low and the (2f) mains peak at 120Hz is only -95dB below peak signal. A very good result for a linear CRCRC PSU. Consistent with the Fluke 101 measurement of 0.2mV rms.
4. The noise floor baseline is also very good at -125dB and there is little noise in the higher frequency band above 1kHz. This should make for a very silent black background for music playback.
This is 8w:
This is 28w:
This is the noise background with no signal:
The new samples of the Vanguard speakers in high gloss finish are here. They sound great paired with a VFET.
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Beautiful finish there, X! When might these hit the market?
Shifting gears, literally. My bench has moved to the garage for now. Working on disc break conversion on all 4 wheels of my ‘69 VW Beetle. One of the best parts is the new tools I’m gathering. In particular a torque multiplier. The rear axle nuts on these cars are torqued to 225ft-lbs. After years of driving it can take over 300ft-lbs or more to break them loose. This tool multiplies torque by almost 10:1 making the task as simple as turning a ratchet.
Shifting gears, literally. My bench has moved to the garage for now. Working on disc break conversion on all 4 wheels of my ‘69 VW Beetle. One of the best parts is the new tools I’m gathering. In particular a torque multiplier. The rear axle nuts on these cars are torqued to 225ft-lbs. After years of driving it can take over 300ft-lbs or more to break them loose. This tool multiplies torque by almost 10:1 making the task as simple as turning a ratchet.
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Clever tool - neat. I gave up doing my car repairs about 20 years ago. Sort of like I gave up doing my own woodwork. Besides realizing what Dirty Harry said, “A man’s gotta know his limitations…”, I also hated skinned knuckles and black grime stuck under the finger nails for days after a repair. But worst part was always realizing I was missing a special tool.
I have seen the “Car Ninja” break a few large socket drive bars or the base of the drive socket when removing the main engine axle nut that holds the fan and pulleys on a BMW 7 series. No “torque multiplier”. Just a long handle and super human strength.
Go to 4:40 in the video:
Another Reason BMW V8 Engines Are JUNK! Timing Chain Guides On A 2001 740i Sport - YouTube
I have seen the “Car Ninja” break a few large socket drive bars or the base of the drive socket when removing the main engine axle nut that holds the fan and pulleys on a BMW 7 series. No “torque multiplier”. Just a long handle and super human strength.
Go to 4:40 in the video:
Another Reason BMW V8 Engines Are JUNK! Timing Chain Guides On A 2001 740i Sport - YouTube
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I definitely pick my battles when it comes to car repair. The minivan goes to the shop. The Subaru, I took to the shop twice, and both times ended up fixing shoddy work myself. I have to find a better shop for that one. The VW is a hobby car. Feels great to keep the old girl running and hopefully pass down to the kids some day.
We have similar taste in YouTube subscriptions, X! Hoovies Garage is great. I bet the Car Wizard has the right tool for the job.
Or probably why he's not the BMW mechanic. I feel like a lot of those cars are a lost cause after watching all the Car Ninja videos from Hoovie.
We have similar taste in YouTube subscriptions, X! Hoovies Garage is great. I bet the Car Wizard has the right tool for the job.
Or probably why he's not the BMW mechanic. I feel like a lot of those cars are a lost cause after watching all the Car Ninja videos from Hoovie.
Speaking of Subaru’s and Beetles, you must have seen this one.
SLEEPER BUG: 517 HP Subaru-Powered 1973 VW Super Beetle | Nicole Johnson's Detour EP1 - YouTube
Hoovie’s garage shows why BMW mechanics are wealthier than their owners.
SLEEPER BUG: 517 HP Subaru-Powered 1973 VW Super Beetle | Nicole Johnson's Detour EP1 - YouTube
Hoovie’s garage shows why BMW mechanics are wealthier than their owners.
I did see that one! Pretty common swap as far as engine swaps for Beetles go. I thought about it for a quick second but all the mods for the water cooling system turned me off. Here's an even better swap IMHO. ..:: Willkommen @ BUGSTER.at ::.. This guy swapped an entire chassis from a Boxster S into/under his Beetle. No surprise, he's German!
No joke, BMW mechanic must be one of the best paid professions!
Back to the Vangards though. How many different speakers are you working on for LSA right now?
No joke, BMW mechanic must be one of the best paid professions!
Back to the Vangards though. How many different speakers are you working on for LSA right now?