Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

DIY the device of US Patent 4,899,387
DIY the device of US Patent 4,899,387
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st March 2018, 06:33 PM   #91
Antoinel is offline Antoinel  United States
diyAudio Member
 
Join Date: Jan 2012
Location: Pennsylvania
DIY the device of US Patent 4,899,387
It appears that this sound system behaves like the device described in the Pass patent under study. It cleanses the room from resonances, and/or removes some bass energy from it . Here's a plausible explanation for the time being. Please refer to the attached and same schematic.

1. Let the voltage source amp [VSA] energize coil #1 so as to enable the woofer cone to [say] move out or travel towards me.

2. DEFcg is a current bootstrap. It simultaneously reacts by fully energizing coil #2. Thus it helps VSA to push the same cone out; because the currents through both coils, and the two coils are in phase.

3. Here's the important connection. A slight vacuum from a standing wave in front of the cone can also pull/move it out towards me. Thus, coil# 1 [and/or #2] become a microphone with a current flowing through it. This simultaneously causes the DEFcg current bootstrap to inject a similar current in coil #2, and thus help/move the cone out. This resultant forward motion of the woofer generates a slight positive pressure which minimizes or wipes out [meaning counteracts] the vacuum as taught by the Pass patent. Essentially absorbing the standing wave per this invention.

4. Let the VSA energize coil # 1 so as to enable the woofer cone to move back or away from me.

5. The resultant reaction of DEFcg current bootstrap is to help the cone continue to move back; meaning in the same direction which was initiated by VSA.

6. Here is the second important connection. A slight pressure at the face of the woofer from a standing wave pushes it back or away from me. The cone and its coils become a microphone. The consequent current bootstrap action of DEFcg pulls the cone back; meaning it keeps it moving in the same direction away from me. This motion of the cone creates a slight vacuum which minimizes or wipes [counteracts] the slight positive pressure from the standing wave and/or resonance. Thus absorbing the standing wave and/or resonances as taught by Pass in his patent.

7. Here is a third important connection. The resonances above are clearly external to the woofer cone from standing waves in the room. But; they might as well be inside the box housing it. This suggests that the combined operation of the loudspeaker [as box microphone too] and the Overall Power Amp [OPA; special!] cleanse/improve the performance of the loudspeaker itself.

Notes left over from previous posts:

1. I am a Bass Trap when I sit in the corner and listen to music. My muscles, some adipose tissues, and the garments I wear are naturally absorbing of base energy. Push comes to shove I may even consider cloaking myself with additional approved bass trap materials to augment the performance of " yours truly" bass trap. I'd say I'll be one funny sight to behold, but absolutely no itchy fiberglass stuff!

2. An error on my part. The longest dimension in my test room is the diagonal from a ceiling corner to the opposite floor corner, and not that on the floor only. The new wavelength of the most offending room resonance [per Pass patent] is ~36 Hz instead of 40 Hz.

Are you ready for a stereo system?

Best
Anton

The prototype amp/loudspeaker system which I listened to and mentioned in the previous post was modified and improved. The new schematic is attached. Additional info is found in the last two posts of the "DEF" thread. Please note the following relevant changes:

1. The location and circuit arrangement of the encircled two voice coils 1 and 2 of the dual voice coil [DVC] subwoofer. The indicated relative phase of the voice coils enables Positive Feedback. Positive feedback is preferred in this application

2. The previous voltage source amp [VSA] which has a possible voltage gain = 21 X [say that of SONY MHC 1750 amp] was replaced with a power buffer/follower [see post in DEF thread].

3. The bias or current idle of the FETs was increased to +/-0.6A. The ideal and future bias will best be at ~+/-1.3 A at +/- 23 Vdc . Because it is the primary source of power to the load.

4. The power buffer/follower delivers a small amount of music power to the voice coil #1 of the subwoofer and thus to its satellite loudspeaker. Little output emanates from this satellite loudspeaker. Consequently, this satellite loudspeaker can be replaced with an 8 Ohm non-inductive power resistor [so as to load the internal high pass crossover network]; but without an effect on sound.

What has not changed?

1. The loudspeaker system is the same and is in the same corner of the room.
2. My listening position is in the opposite corner along the floor diagonal [~28 feet away].

Subjective observations:

1. The bass is thunderous, clean and tight.
2. The rest of the audio spectrum is highly detailed. Vocals are intelligible and crystal clear.
3. Could not detect standing waves by walking towards the walls of the room.
4. Listening to this system for an hour+ was a satisfying experience. And that is my objective
5. This music system is stable against oscillation; provided the power buffer to its input is connected [see the last 2 posts in the DEF thread].

More to post on absorbing acoustic trash in the listening room...

Best
Anton
Attached Images
File Type: png DEFcGRA.png (50.4 KB, 331 views)
File Type: png DEFcGRA1.png (51.6 KB, 299 views)
  Reply With Quote
Old 10th July 2019, 10:46 AM   #92
yentzee is offline yentzee
diyAudio Member
 
Join Date: Jun 2019
Awesome, not being a native speaker nor trained in electronics it will take me some time to fully understand what is going on and build some of those myself (It would be great to know some parts that work well and are not too expensive). Until then I am using a dsp with an electret mic but I highly appreciate your work and that you share all those information. Best regards from Hamburg
  Reply With Quote
Old 10th July 2019, 01:32 PM   #93
oreo382 is offline oreo382  Canada
diyAudio Member
 
Join Date: Jan 2013
Location: Winnipeg
Lol,after reading all this wizardry i'll just crawl back under my cone of dumbness
  Reply With Quote
Old 10th July 2019, 01:55 PM   #94
Antoinel is offline Antoinel  United States
diyAudio Member
 
Join Date: Jan 2012
Location: Pennsylvania
DIY the device of US Patent 4,899,387
Thank you yentzee and oreo382 for your posts. I hope that you experiment with this set up. One's ears are the final and sole judge..
  Reply With Quote
Old 11th July 2019, 11:48 AM   #95
Schlumpfpeter is offline Schlumpfpeter  Germany
diyAudio Member
 
Join Date: Jul 2015
Location: UK near London
Quote:
Originally Posted by yentzee View Post
Awesome, not being a native speaker nor trained in electronics it will take me some time to fully understand what is going on and build some of those myself (It would be great to know some parts that work well and are not too expensive). Until then I am using a dsp with an electret mic but I highly appreciate your work and that you share all those information. Best regards from Hamburg
Thanks for showing me this thread!

Amazing design!

..... but I'm afraid I'm going to join oreo382 under the blanket of dumbness

Quote:
Originally Posted by Antoinel View Post
Thank you yentzee and oreo382 for your posts. I hope that you experiment with this set up. One's ears are the final and sole judge..
While I trust my ears to some extent, I trust a propper REW before/after meassurement even more.

Some day I might even build this one here and then I will surely post some of the meassurements here.
  Reply With Quote
Old 11th July 2019, 04:41 PM   #96
Antoinel is offline Antoinel  United States
diyAudio Member
 
Join Date: Jan 2012
Location: Pennsylvania
DIY the device of US Patent 4,899,387
Hello Schlumpfpeter and thanks for your post. Mr. Pass [and others] do encourage DIYers to experiment and to test [personal] or their hypotheses. How else can I unravel possible sonic/subjective improvements? I continue to experiment with the subject matter. IMHO, minimizing standing waves [SW] and their impact in my listening room is the last frontier to conquer; but with an additional enhancement. I hope that you and others:

1. Had the opportunity to experiment with the remarkable DEF circuit of Mr. Pass. A gem!

2. Noted in my posts the suggested and evolved hypothesis to use any loudspeaker in the corner of the listening room so as to enable it to do double duty [like a bat]. Send high fidelity music to my ears and simultaneously "suppress" the returning [SW] echoes. This approach will also free space in the room for "dancing" from absent expensive loudspeakers which can be toppled over as lovers sway back and fro.!

Best wishes
Anton
  Reply With Quote
Old 12th July 2019, 12:25 PM   #97
Schlumpfpeter is offline Schlumpfpeter  Germany
diyAudio Member
 
Join Date: Jul 2015
Location: UK near London
That is indeed, a very interesting idea, to use the speaker itself for the cancelation of the standing waves. Only thing which comes to my mind is that you would need to have a speaker using a double coiled subwoofer. I don't think that those special SWs are that common, at least I haven't seen one.
  Reply With Quote
Old 12th July 2019, 03:05 PM   #98
yentzee is offline yentzee
diyAudio Member
 
Join Date: Jun 2019
Definitely gonna try this at one point. Getting the low end right takes so much space if done using porous absorbers
  Reply With Quote
Old 12th July 2019, 06:47 PM   #99
yentzee is offline yentzee
diyAudio Member
 
Join Date: Jun 2019
Sorry to ask a dumb question but are all the values of the components known? If so I would just try to build it. Using a dsp with mic and phaseshift at the moment but "sucking" bass away instead of tryin to cancel by intereference seems really interesting.
  Reply With Quote

Reply


DIY the device of US Patent 4,899,387Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
DIY Single-Tube Directional surveillance device JimDiGriz Everything Else 0 24th October 2012 05:00 PM
mcintosh pcb 043-899 lizo Parts 0 8th February 2012 10:36 PM
Idea for Volume Control Device (DIY) Edin PC Based 1 22nd January 2012 07:24 PM
DIY GPRS device Grandma´s_SUB Everything Else 0 8th January 2007 04:39 PM
a great device for diy freaks ???? ergo Solid State 0 10th October 2001 03:34 PM


New To Site? Need Help?

All times are GMT. The time now is 01:00 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki