Increase (electrical) Damping of a Driver

[bmc0]

Ahem, the microphonic voltage of a VC is always proportional to velocity at all frequencies.

Oops; thanks for the correction.

DF itself was not a factor of increased control, but an indication of it, because it rises as a side effect of effective negative feedback and loop gain application, which, as you indicate, DOES improve load-invariant response and thereby pistonic driver behavior.

Better control of diaphragm motion does not follow from load invariance. Whether a diaphragm is pistonic at a given frequency is virtually entirely determined by its mechanical design, not anything to do with the driving amplifier. Load invariance is a result the output filter being subject to negative feedback control (i.e. inside a feedback loop). Linear amps (class A, A/B, B, etc) are almost always "load invariant" in this sense without any fancy feedback techniques because they do not require output filters like class D does.

 

[smowry]

NTK@ said, "Anyhow, you know much more on loudspeaker system design than me. Sorry for interrupting."

Thank you but any System Design work that I do today is as a hobby exercise only and that makes me an amatuer. Professionals typically get paid for their work.

 

[smowry]

Quoting Purifi's discussion article, "A so-called “iron-free” motor is inherently free of FFM. Permanent magnets are fully saturated. Their AC permeability is pretty much that of air. On the downside, it costs a fortune in magnets and without iron you can’t focus the magnetic field. That makes it harder to control the shape of the Bl(x) curve."

Some folks will pay US$10,000 or more for a power amplifier but refuse to pay US$1,000 for an almost air core transducer. I attempted to champion "iron-free" transducer development in the past; however, the only significant response was for Michael Borresen to claim my work as his invention. Charlie Hansen from Ayre did fund some of my work but he became ill and subsequently passed away before we could complete our projects.

https://pearl-hifi.com/06_Lit_Archive/14_Books_Tech_Papers/Mowry_Steve/Steallus_Motor_Design.pdf

https://pearl-hifi.com/06_Lit_Archive/14_Books_Tech_Papers/Mowry_Steve/Air_Core_Tweeter_Magnet_Assy.pdf

https://patentimages.storage.googleapis.com/ee/58/7f/2bcce6b865b6e7/US10993035.pdf

 

[smowry]

My present interest in new transducer development, essentially as an observer, is complementary symmetrical topology. This can be implemented with one symmetrical drive motor assembly and two diaphragm assemblies or one diaphragm assembly and two asymmetric (typical motor topology) motor assemblies with a potential for commutated voice coils.

 

[smowry]

My application is an active loudspeaker with a Radian 6CRF5130 - 6.5” coaxial with planar ribbon HF (https://cdn.shopify.com/s/files/1/0111/0324/0254/files/6CRF5130-data-sheet.pdf?1165) with gold plated ferrous binding posts replaced with copper fishtail lugs and nylon fasteners in an acoustic resistive enclosure . The Topping B100 drives the ribbon, while the B200 drives the low frequency cone transducer. There is also an active cardioid woofer (Woofer - Coaxial - Woofer) array with 2 x Hotroded (added bucking magnets) 10" Peerless XLS woofers and 1 x Hotroded 10" Peerless XLS anti woofer in equalized sealed tubes, 3 x 25 liter. A miniDSP FLEX Htx is the processor et al. All interconnects are balanced. The 2 ohm (parallel) woofers and the 4 ohm anti woofer are driven by Fosi V3 Monoblocks. Topping and Fosi products are readily available at competitive prices in Thailand with good warranty service.

Here's 2 pics of the system enclosures. The entire structure is composed of PVC pipe and fittings. The amps are housed within the bottom pipe stand. I am preparing to paint. I will post a thread on the DIY Project soon.

 

[smowry]

DIY "Maximizing Damping of a Driver" within a loudspeaker system in a practical sense based on the GENELEC Model.

1. Active loudspeaker system with no components (R L C) between the power amplifiers and the transducers.
2. Power amplifiers integrated into the loudspeaker topology as close to the transducers as possible.
3. 14 AWG or larger OFC hookup wires that are soldered to non-ferrous transducer terminals and with copper banana plugs at the amp's output connection only, no loudspeaker binding posts.

 

[Salt]

Here's 2 pics of the system enclosures. The entire structure is composed of PVC pipe and fittings. The amps are housed within the bottom pipe stand. I am preparing to paint. I will post a thread on the DIY Project soon.

View attachment 497790

View attachment 497795

Any new aspects to this?

 

[smowry]

Any new aspects to this?

Hi Salt! Yes, I have added 30 mm hard wood dowel cross braces and 2 inside coats of a nasty sand + epoxy resin mix to each woofer/anti-woofer enclosure.

 

[Salt]

Maybe I missed the forum thread about this...

 

[smowry]

Maybe I missed the forum thread about this...

No, there is no thread yet. I will message you when I start the DIY thread.