diyAudio Full Range Reference Project - Page 20 - diyAudio
 diyAudio Full Range Reference Project
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 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
diyAudio Member

Join Date: Apr 2004
Location: Winnipeg, Manitoba
Re: Re: Mono-pole vs Bi-pole

Quote:
 Originally posted by planet10 GM -- you need to shake the brain-washing... For a tube amp with proper taps you will get the 3 dB of extra sensitivity whether you connect in series or parallel... 6 dB is an artifact of MJK assumming everyone is using a SS amp with high damping (1/2 of the 6 dB gain from parallel is from assumming that the SS amp doubles its power into 4 ohms and -3 dB in the case of the series connection comes from the SS amp putting out half as much power into 16 ohms. (ie the 6 dB difference between parallel & series is purely that into 4 ohms the amp is providing 2 W & into 16 ohms a 1/2 W -- this is a completely false assumption if you have a tube amp) dave

I hope I am not being brain washed! If so, here is your turn!

What do you mean by a "tube amp with proper taps"?

To summarize what you have said, if one uses a tube amp to drive this bi-pole, the sensitivity will be about 93dB regardless of weather it is wired series or parallel.

Cheers,
Gio.

diyAudio Member

Join Date: Jul 2003
Location: Seattle, WA
Quote:
 The bi-pole port radius should be SQRT(2 * 0.75) = 1.225". I have attached a MJK mathCAD simmulation of the larger port.
Yes, that's the correct formula. Something strikes me odd about using a 2.5" port though. The modeling shows little difference other than slightly lower port velocity and slightly higher box tuning.

 12th December 2004, 07:01 PM #193 frugal-phile(tm) diyAudio Moderator     Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5 When Tim specified the bi-pole he gave a 2" port... for the monopole i divided the area in half, it came out to 1.4x something diameter so i just rounded it to 1.5" since that is a standrad size in NA... it may need to be a tad longer because of that approximation. Until someone actually builds them, the port size is really just a close approximation. dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA
frugal-phile(tm)
diyAudio Moderator

Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
speaking of monopole... here is the up-to-date round-top folded monopole....

dave
Attached Images
 diya-frref-roundtop-mono.gif (17.2 KB, 3445 views)
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA

frugal-phile(tm)
diyAudio Moderator

Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Re: Re: Re: Mono-pole vs Bi-pole

Quote:
 Originally posted by gmilitano What do you mean by a "tube amp with proper taps"? To summarize what you have said, if one uses a tube amp to drive this bi-pole, the sensitivity will be about 93dB regardless of weather it is wired series or parallel.

Tube amps have taps on there output transformers, typically at least 4 & 8 ohm, or 8 & 16 ohm (or 5 & 10 ohm on some older German OPTs). The idea is to connect the speaker to the one that is closest to your speaker. Now if your speaker doesn't correspond to the right tap (ie a 16 ohm speaker on an 8 ohm tap) you will get a little less power (in the case of the example shown usually a little less distortion also), but in the end the power output differences between taps is usually not all that great, and the best way to determine which one to use is the one that sounds best.

Yes... real sensitivity of 2 speakers in parallel or series will be 3 dB greater than a single one. And tube amps (and most SS amps for that matter) are happier with higher impedance (it is just that the SS amp typically puts out less maximum power -- ie it has a relatively more robust power supply just by changing speaker impedance)

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA

 13th December 2004, 01:13 AM #196 diyAudio Member   Join Date: Nov 2002 Location: Auckland, New Zealand I have two questions: First, is the purpose of this reference speaker simply for doing A/B test with other speakers. Or to provide a flat full range response? Personally i would prefer a reference speaker with a flat response to compare others to, rather than a speaker modelled to sound 'good'.. Secondly, does anyone know where to get Fostex drivers in New Zealand? Thanks guys, keep up the good work Matt
diyAudio Member

Join Date: Aug 2004
Location: Iowa
Quote:
 Originally posted by planet10 speaking of monopole... here is the up-to-date round-top folded monopole.... dave

I think i may give these a go next weekend...got some time on my hand...now this is basically my first DIY home audio project. Sence it looks "cute" according the the boss....i got the approval..so with that...i had one question...would anyone have any recommendations on stuffing...as in how much and where exactly.

thank you

diyAudio Member

Join Date: Jul 2003
Location: Seattle, WA
Quote:
 Originally posted by Optical I have two questions: First, is the purpose of this reference speaker simply for doing A/B test with other speakers. Or to provide a flat full range response? Personally i would prefer a reference speaker with a flat response to compare others to, rather than a speaker modelled to sound 'good'.. Secondly, does anyone know where to get Fostex drivers in New Zealand? Thanks guys, keep up the good work Matt
I believe the suggested designs in this thread provide an adequate standard to base future builds against when taking price, performance and construction requirements into consideration.

diyAudio Member

Join Date: Jul 2004
Location: Wherever I hang my hat...
Quote:
 Originally posted by Optical ... does anyone know where to get Fostex drivers in New Zealand?

Hi Matt,
Syntec in Auckland is the Fostex agent. Ph 263 9885. I spoke to Conrad when I phoned recently with an enquiry about drivers.
__________________
"Everything should be made as simple as possible, but not simpler." - Einstein

 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 OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

 New To Site? Need Help?

All times are GMT. The time now is 10:25 AM.