Dan should stick to marketing, designing the bling cases and employ someone who knows what they are doing to design the electronics.
I get he doesn't like feedback (because it goes 'around and around' what can I say . . .that old chestnut again) but the plots look like there's other gross problems in the mix on his amp.
The well of probity, honesty and good electrical performance has been poisoned by the review community and hi-fi journos that except for a few individuals aren't qualified to hold a soldering iron. Sort of reminds of a picture someone put up a few weeks ago of a guy (obviously a model of some sort) holding a soldering iron like a ball point pen - you know, just above the tip 😀. I would loved to have flicked the switch on!
Virtually all closed box speakers and all ported/passive radiator speaker exploit resonances to extend the bass. Even panel speakers.
The issue is managing those resonances. They need to be suitably broad, well damped and not too strong to louse up the balance.
Bass extension without resonances can be done but not easily, usually needing some kind of feedback/servo etc. to control the cone motion.
Oh dear.
I did however say 'employ someone who knows what they are doing to design the electronics'
😀
They keep blaming bias drift. If an amp drifts bias that much in a couple of days its a piece of s**t. And a $45k piece of s**t that gets great reviews from an audio rag.
I'm embarrassed to be called an audiophile and be in the same group as that.
I'm embarrassed to be called an audiophile and be in the same group as that.
Ha, ha, I also want a Super Rail with turbo 😀
Or is it that they are using Class-G, causing the THD to go up first and then suddenly go down at higher power output ?
Never seen such strange THD before, can't think of any other reason.
Hans
I have come to conclusion that it is hopeless. The time is a precious thing and getting older one may not be willing to spend it in useless activities.
Of course Pavel, completely agree. Others with plenty of resources to spare will shoulder the burden.
Not to forget EQ. Closed box and EQ (LT) to taste at Q=0,5. This will become a non resonant system (if box is ideal 🙂)
//
I don't think it's hopeless. Don't forget the silent majority out there. When I was surfing the net for reviews on products (electronics & others), those who questioned / called out nonsense were helpful even though I didn't post thank you note because I wasn't a member of the forum or didn't have time. Without those who spent time calling out nonsense, I would have been much thinner in the pocket and hair (pulling due to frustration).
Regarding current drive, looks like it's all been done nearly 20 years ago. Tip_49 (No date to the article, but some of the graphs are dated '04)
The F1 amplifier has an output Z of 80 Ohms. The speaker crossover is designed to work with that impedance level. The author concludes; "Kudos to Nelson Pass for turning at least a few of us onto the joys of current drive".
Is it really so bad as an idea? Why all the thrash over it in 2021? One would think if you like it, here's how, if not, fine. One would also think "current drive" would have its own sub forum, rather than sprinkled throughout all the others. What, it's not significant enough?
The F1 amplifier has an output Z of 80 Ohms. The speaker crossover is designed to work with that impedance level. The author concludes; "Kudos to Nelson Pass for turning at least a few of us onto the joys of current drive".
Is it really so bad as an idea? Why all the thrash over it in 2021? One would think if you like it, here's how, if not, fine. One would also think "current drive" would have its own sub forum, rather than sprinkled throughout all the others. What, it's not significant enough?
"Tip 49. February 2005 - The First Watt Model F1 Current Drive Power Amplifier
And Introducing a pair of matching DIY Loudspeakers: The BassZilla Leopard and Panther"
Dick Olsher's "Tip of the Month" | Black Dahlia
And Introducing a pair of matching DIY Loudspeakers: The BassZilla Leopard and Panther"
Dick Olsher's "Tip of the Month" | Black Dahlia
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I think a lot of people are scared about it because it's not seen in commercial products. Why it's not been seen more in DIY I'm not sure but I suspect it's that amp designers don't generally design speakers and vice versa. Nelson is a bit of an outlier (and likes the type of speakers that react well to current drive).
Add in that the technique works best with active or full range speakers and active isn't very popular in DIY land and you can see why it's not talked about much.
Having said all that there are people who design speaker to work well with tube amps. Maybe they have always been aware of that but don't talk about it.
My personal interest is the distortion reduction and whether that is worth having.
It’s like the Wankel rotary engine.
Basically a very nice concept, but it came simply too late to change the market with a huge installed base in reciprocal engines and never could reach te same level of maturity.
Current drive with many advantages suffers the same faith.
Les jeux sont fait, the market has settled for a standard and it’s too late for a change. Clever workarounds are constantly being invented to reduce the disadvantages of voltage drive, thereby making the advantages of current drive smaller and smaller.
Hans
Basically a very nice concept, but it came simply too late to change the market with a huge installed base in reciprocal engines and never could reach te same level of maturity.
Current drive with many advantages suffers the same faith.
Les jeux sont fait, the market has settled for a standard and it’s too late for a change. Clever workarounds are constantly being invented to reduce the disadvantages of voltage drive, thereby making the advantages of current drive smaller and smaller.
Hans
Rotary engines?
Radial engine - Wikipedia
Wankel is one of the three types produced in quantity.
Of course the first two would not be practical for automotive use.
Radial engine - Wikipedia
Wankel is one of the three types produced in quantity.
Of course the first two would not be practical for automotive use.
Aero rotaries were a bonkers idea.
There is of course the Napier deltic Napier Deltic - Wikipedia . Three crankshafts, one of them counter rotating. Never got my head round how the gearboxes worked on those.
There is of course the Napier deltic Napier Deltic - Wikipedia . Three crankshafts, one of them counter rotating. Never got my head round how the gearboxes worked on those.