Interesting because I was using the Neurochrome 86 which was clearly better than a Leach fully regulated LOW TIM III, Fully regulated Leach Super Amp with match transistors, Borbeley Mosfet. The AHB2 simply changed the characteristic of a pair of Polk LSIM 707s. These speakers are much more demanding than what they say. What they say of the AHB2 was so quick to perceive, the dynamics and extension was immediate then the articulation of instruments and voices is so good. You hear the real performance. I use my system to watch TV as well. The ease with which you hear the space of the rooms people are in is also interesting. I am happy I sprung for them because they will finally end the quest of what I was looking for since 1977.
It's not a warm sound nor is it etched. The low end has dynamics and it a full bass but not wooley and slow and it has fantastic extension all the bass your speaker can naturally provide, it will bring out. It has SLAM when it call for it. The Neurochrome 86 sounds similar in character but it is unable to have the same bass control and punch but it gets close in the same direction. The AHB2 is much more open than the Neurochrome 86 despite similar specs. The AHB2 has excellent high end resolution, never sounding harsh but the deatils are all there. As soon as you push the volume level, the Neurochome 86 is not in the same league but I do my listening at lower levels, not even close to what the 86 limits. And it is here where the AHB2 is uncanny....you hear a lot more from the AHB2 at LOW listening levels. It is so tuneful and full sounding at low levels. That aspect is excellent for me.
I have yet to test it with my older B&W 802Fs. Maybe those speakers really needed this amp to come alive! The LA4 is certainly plays a part as well. It sounded as transparent as my passive but the passive was too lifeless.
My amplification journey now takes a stop.
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I think we have similar goals in what we expect from our system. I think the magic happens with the accurate reproduction of low level information together with dynamic range and transient response. From what you have said and I have quickly read, the Benchmark sounds like it hits all the right spots. It would be interesting to compare it to some Pass designs. There is DIY meeting in the making!
I noticed it uses low amount of feedback. I was listening (as best you can on YouTube) to a Gryphon Mephisto compared to a mega watt Boulder amp. Even over YouTube I commented that the Gryphon sounds like low feedback. Quick look at it's marketing blurb and sure enough, great specs without feedback.
I noticed it uses low amount of feedback. I was listening (as best you can on YouTube) to a Gryphon Mephisto compared to a mega watt Boulder amp. Even over YouTube I commented that the Gryphon sounds like low feedback. Quick look at it's marketing blurb and sure enough, great specs without feedback.
Power Amplifiers - A "First Watt" ABX Test - Benchmark Media Systems
The above article by Benchmark makes for interesting reading. First it actually follows the same philosophy as Pass's First Watt. The both of them are on the same page. Pass prefers to go the Class A route, Benchmark takes another direction to achieve the same goals. The last amp I was using was the Leach Super Amp, 300W per channel fully regulated and I was now tiring of the size of it as well as the heat it produced.
Then when the pandemic began I started to play more with "chip amps" and they possessed something about them that was correct but not all was right. Just beyond a certain level of output they fell apart. Then the Neurochrome 86 was tried and it had a difficult time handling the low frequencies at moderate levels. I imagine they would be perfect for much more efficient speakers. I then wondered if I should disassemble the Super Leach, remove the four 500VA toroids and use it for the Neurochrome 686. Again the size and heat produced swayed me. So I bit the bullet.
What is also interesting is that beyond the Fletcher Munson effects, which I thought was responsible for my turning up the volume to enjoy the music, it might have been the very aspect of the First Watt philosophy and the level and characteristic of distortion at low output levels that was the problem. So maybe Pass and the article above has merit, Tube SET probably don't have the crossover distortion being single ended but we do know they add some nice sounding distortion into the output. Again heat and the longevity of tubes was an issue for me.
I'll bring the Neurochrome setup/ stack at the next meet. When?
The above article by Benchmark makes for interesting reading. First it actually follows the same philosophy as Pass's First Watt. The both of them are on the same page. Pass prefers to go the Class A route, Benchmark takes another direction to achieve the same goals. The last amp I was using was the Leach Super Amp, 300W per channel fully regulated and I was now tiring of the size of it as well as the heat it produced.
Then when the pandemic began I started to play more with "chip amps" and they possessed something about them that was correct but not all was right. Just beyond a certain level of output they fell apart. Then the Neurochrome 86 was tried and it had a difficult time handling the low frequencies at moderate levels. I imagine they would be perfect for much more efficient speakers. I then wondered if I should disassemble the Super Leach, remove the four 500VA toroids and use it for the Neurochrome 686. Again the size and heat produced swayed me. So I bit the bullet.
What is also interesting is that beyond the Fletcher Munson effects, which I thought was responsible for my turning up the volume to enjoy the music, it might have been the very aspect of the First Watt philosophy and the level and characteristic of distortion at low output levels that was the problem. So maybe Pass and the article above has merit, Tube SET probably don't have the crossover distortion being single ended but we do know they add some nice sounding distortion into the output. Again heat and the longevity of tubes was an issue for me.
I'll bring the Neurochrome setup/ stack at the next meet. When?
Tube SET probably don't have the crossover distortion being single ended but we do know they add some nice sounding distortion into the output.
Another mechanism may be at play. If the amplifier's distortion is low order and approximately the magnitude of the speaker's it can reduce distortion reaching the listener. It's measurable and potentially significant.
The REW plots below used a pentode SET with ~0.35 THD @ 1 watt, predominantly 2nd order with the 3rd about 0.03%. 4th is about 100db below fundamental. The speaker is an ancient tweaked PSB Alpha Mite used for bench testing. The measurements were quick and dirty at a distance of under 1 foot, the speaker on a paint can and the mic resting on a bench vice.
Distortion reduction is clear on either side of the 3kHz crossover point when speaker phase is reversed. REW gives THD2-9 figures of 0.487% and 0.141%. I would expect one polarity adds distortion as well. For completion this needs to be followed up with equivalent plots using a standard low distortion amplifier. This SET also permits 'tuning' the level of the 2nd harmonic with minor bias/B+ changes, suggesting more effective cancellation is possible. I would also anticipate more broadband cancellation from a crossover-less full range driver.
SET feed-forward?
Another mechanism may be at play. If the amplifier's distortion is low order and approximately the magnitude of the speaker's it can reduce distortion reaching the listener. It's measurable and potentially significant.
The REW plots below used a pentode SET with ~0.35 THD @ 1 watt, predominantly 2nd order with the 3rd about 0.03%. 4th is about 100db below fundamental. The speaker is an ancient tweaked PSB Alpha Mite used for bench testing. The measurements were quick and dirty at a distance of under 1 foot, the speaker on a paint can and the mic resting on a bench vice.
Distortion reduction is clear on either side of the 3kHz crossover point when speaker phase is reversed. REW gives THD2-9 figures of 0.487% and 0.141%. I would expect one polarity adds distortion as well. For completion this needs to be followed up with equivalent plots using a standard low distortion amplifier. This SET also permits 'tuning' the level of the 2nd harmonic with minor bias/B+ changes, suggesting more effective cancellation is possible. I would also anticipate more broadband cancellation from a crossover-less full range driver.
SET feed-forward?
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I'm pretty good.
I've got my first dose, and I'm open to having a couple of people over to check out my amp/PCB designs if they want. We're gonna be able to have small gatherings soon.
I'd also like to offer some free boards to those interested to get opinions etc.
There are so many posts on here about using toroid PTs as OPTs, and I've been doing it for years now. It would be great if someone else on here could listen and give their opinion, too.
I even have amplifiers built that I could loan out and or sell.
I also hope all is well among our GTA members.
I've got my first dose, and I'm open to having a couple of people over to check out my amp/PCB designs if they want. We're gonna be able to have small gatherings soon.
I'd also like to offer some free boards to those interested to get opinions etc.
There are so many posts on here about using toroid PTs as OPTs, and I've been doing it for years now. It would be great if someone else on here could listen and give their opinion, too.
I even have amplifiers built that I could loan out and or sell.
I also hope all is well among our GTA members.
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Joined 2009
Paid Member
One thing that I discovered years ago opened my ear. I was attending a "music night" get together organized by a high end dealer in Montreal. Attendance was by invitation only and the shop was closed for business that night. They set up a few of their high end ensembles in different listening rooms. I have the opportunity listening to the Sonic Frontiers Power 3 mono-blocks driving a pair top of the line ProAc. It was wonderful and made me realized that a tube amp can also be dynamic, produce solid punchy low bass without getting bloomy. Female voice was sweet and natural. But the biggest surprise (for me) was in a smaller listening room where a pair of the top of the line Mark Levinson was driving a pair of Watt and Puppy. We turned the volume up so loud that the walls were shaking. The amazing thing was that the sound did not get distorted, just got loud, very loud. No smearing of the sound at all. The transients were as sharp as it was at lower sound pressure level. The dynamic was unbelievable, so was the bass (I recalled the room has some sound treatment). A few of us stay in the room to listen for a while at such a loud volume and no one left. That was the time I learned that turned up the volume does not necessary means the sound will get distorted - something that happens so often with a lot of amps-speaker combinations.
Unfortunately, I will never be able to afford that set - just the pair of ML amps costed over $100000. I was glad I went that night!!
Hope we shall meet again sometime in the fall
Regards,
By the time we meet up again I’ll have a new amp to check out. We are working on the Bc-1 design in Bob Cordell’s book. We have redone the pcbs and are putting them in a hifi2000 3Ux300mm dissipante chassis. Designing an amp that is easy to assemble and with high performance is the goal using readily available parts. Let’s see how the timing works out for later in the year once things open up again. I am scheduled for my second vac shot in August, but many will not be done too much later so who knows if meetings are possible for this year = get your shot ASAP
Green with envy, Lo_Tse, for the experience of an evening in a high end audio room. Your description brought the evening to life.
Sounds like an interesting project rsavas.
WRT vaccination, I'm scheduled for 2nd shot at the end of July. I expect it will move up earlier. The real issue will be giving it enough time that both my wife and I are comfortable with hanging out with strangers for an afternoon. That will take longer. I think it will be important to establish if full vaccination is a prerequisite to attend. IMHO, everyone is entitled to make their own choices, but also should expect to have limited welcome if they opt out of the herd immunity. I realize that's not a popular statement but its a conversation that will need to happen. If I am alone in that thought, then I'll remain engaged through the thread and leave the 2021 in person meet to the more adventurous.
Sounds like an interesting project rsavas.
WRT vaccination, I'm scheduled for 2nd shot at the end of July. I expect it will move up earlier. The real issue will be giving it enough time that both my wife and I are comfortable with hanging out with strangers for an afternoon. That will take longer. I think it will be important to establish if full vaccination is a prerequisite to attend. IMHO, everyone is entitled to make their own choices, but also should expect to have limited welcome if they opt out of the herd immunity. I realize that's not a popular statement but its a conversation that will need to happen. If I am alone in that thought, then I'll remain engaged through the thread and leave the 2021 in person meet to the more adventurous.
OK kids, getting my second Pfizer shot in three days. Nice that the province is looking kindly on the mortality of us frail elderly folk. But I'm likely to be the only 80 yr old showing up on a motorcycle.*
Ben
*1999 BMW R1100S... for sale:
1999 R1100S, most beautiful BMW ever in black, gorgeous cond., many goodies, Toronto - Bikes for Sale - Show Ad - The Internet BMW Riders
Ben
*1999 BMW R1100S... for sale:
1999 R1100S, most beautiful BMW ever in black, gorgeous cond., many goodies, Toronto - Bikes for Sale - Show Ad - The Internet BMW Riders
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Green with envy, Lo_Tse, for the experience of an evening in a high end audio room. Your description brought the evening to life.
Sounds like an interesting project rsavas.
WRT vaccination, I'm scheduled for 2nd shot at the end of July. I expect it will move up earlier. The real issue will be giving it enough time that both my wife and I are comfortable with hanging out with strangers for an afternoon. That will take longer. I think it will be important to establish if full vaccination is a prerequisite to attend. IMHO, everyone is entitled to make their own choices, but also should expect to have limited welcome if they opt out of the herd immunity. I realize that's not a popular statement but its a conversation that will need to happen. If I am alone in that thought, then I'll remain engaged through the thread and leave the 2021 in person meet to the more adventurous.
Walter,
My second dose is also scheduled a the end of July. The recent data (don't remember from which source) showed that even after the first dose, the protection efficacy is > 95%!! And if I remember correctly, no one that has received the full 2 doses died from a COVID-19 infection, even if the person got infected (post vaccination). I am of the same opinion as you and I think vaccination is the only way to deal with the pandemic. I have a high school classmate that suffered from Polio infection when he was very young, and he has to hop around on one good leg all his life. A big thank you to Salk who invented the Polio vaccine and save tens of thousands of kids world wide from life long misery.
I am cautiously optimistic that a get together for our group is possible this fall
.Take care!!
Regards,
Lo_Tse I agree. We are blessed to have an amazingly effective vaccine about a year after this thing hit. Last year I thought we'd be lucky to have one in three years. So we have a lot to be thankful for. All indications point to very high probability of being spared any serious complications if we get exposed. Gatherings of fully vaccinated people will be very low risk unless a new variant comes along. Current stats in the US... of 130m fully vaccinated, 10k have had a breakthrough case, 1k hospitalized and only 160 have died. I believe you are correct. I don't think we've had any deaths in Canada. More likely to die in a car accident on the way to the meeting.
Rick,
I remembered you brought a prototype of your amp to the meet last time. It really is a labour of love, ehh.....
Looking forward to hear your amp next time.
Regards,