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Take Two: 2 way Open Baffle DIY Attempt

Home Theatre Systems

yogibear

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My indulgence in 2 way OB took a further leap. I am frugal in my approach and try to keep line-up as simple as possible. Please refer to my earlier post on my 2 way OB for initial details. The source in early line-up was flac, lossless format played by Vox from headphone out and fed to Dynaco ST 35 driving FRDs with no crossovers and bass drivers crossed at 120Hz and driven solid state by 250 watts amp.

I wanted to try a CDP as source and hence a preamp was needed. Please refer to the pictures of the update.

Source: JVC DVD XV-D723GD
Preamplifier: Re084 Tube DHT Preamp. Point to point wiring, with Siemens / Philips components.
Amplifier: Dynaco ST 35 EL84 tube Push Pull

Sonic Impressions: Perfect Analogue Sound !!! I do lose some low end as I cannot boost the lowest octave as I did on Vox. However its surprisingly sweet sounding, sweetest I should say, excellent clarity, details, no fatigue and gets scaringly loud with non-existent distortion. I can listen to this for endlessly, getting more and more amazed. Dead silent even with my high dB drivers. I wonder what a SET DHT amplifier plus an audiophile CDP will do to this line-up ! Sounds beautiful from 18K down to 40Hz. Will post measurements once I get to learn playing with Umik 2.

Thanks for reading. Comments / suggestions are welcome ! I am still learning and exploring........ Pardon my sin of placing the DVD on a cheapo table. My DIY audio rack is pending an upgrade.


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amangujral06

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Nothing sounds sweeter then a DIY build. I see you are from jaipur, I often visit there and would love to listen to these beasts if gotten a chance to.. How is the imaging on these ? I Often struggle to meet my expectations in imaging department with my OB builds .
 

Hari Iyer

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OB has diffuse sound as sound from the rear of the drivers hit the front wall and get diffused. Hence imaging suffers a bit, but as other put you get more lively and open sound. As FM Prem puts it, live music does not have imaging and every sound is in a stage like point source. It's more of what you prefer open live sound or excellent center imaging.
 

yogibear

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Nothing sounds sweeter then a DIY build. I see you are from jaipur, I often visit there and would love to listen to these beasts if gotten a chance to.. How is the imaging on these ? I Often struggle to meet my expectations in imaging department with my OB builds .

You are most welcome. PM me when you are around. Cannot really comment on imaging but Soundstage is staggering. I have nailed the midrange and HF quite a bit but bass department needs more experimenting.

It’s just a little stepping stone experiment for me but definitely the right direction towards getting as much close as possible to live reproduction. Bad recordings sound bad and good ones like Sony DADC amaze me.

It’s far from a final shape that I would like to build and rest on but for now serves me great for leisure listening, experimenting and comparing different FRDs and tube sonic signatures.
 

Sumanta

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OB has diffuse sound as sound from the rear of the drivers hit the front wall and get diffused. Hence imaging suffers a bit, but as other put you get more lively and open sound. As FM Prem puts it, live music does not have imaging and every sound is in a stage like point source. It's more of what you prefer open live sound or excellent center imaging.

With due regards, I would state from my experience which is diametrically opposite. The first thing that hit a properly seated audience by a well designed and placed OB is the precise imaging. Such is the precision that changing head position by inches changes imaging position by more than inches. That's how it should be as the wide stage is converging to a single point between ears. The difference of air pressures between ears need to be precise to have a sense of imaging to start with.

I have never heard someone speaking such thing about OB unless he/she has not heard a good one. But I have always read bad perceptions about OB, as very less have actually changed the perception with reality. Just because rear waves cancels front waves, it is not practically a low quality bass that OB generate, rather it avoid room impact a lot.

This, I am speaking from my 5 or so years of speaker design, study, pursuing others to listen to OBs. Omni speakers come very close to imaging of OBs, and are confirmed by Riley too with his comparison of Pluto and his Orion.

I request all to go out & listen to good OBs. The return on investment (DIY or straight purchase) is immense. My guess is, imaging of bass could be muddy if we use OB mid and cabinet lows, but I am not too sure. By the way, I have experienced imaging of bass too unless we talk about lower than 60~70 Hz. Others may disagree.

High Qt is not so important for mid frequency drivers. For playing bass, I think having greater SPL of LF drivers than the mid is more important than having Qt towards 1. It's a myth that drivers of 0.7~1 is a must for all drivers. How the whole system is synchronized is the first governing factor for performance. Ahuja drivers I use for LF have Qts of 0.54. they play superb bass.
Please do not think/perceive/design one item in isolation. Think of a system, think of the room too. Then the design will be the best compromised design and most economical.
 
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Sumanta

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One more point, if live music means live at a big ground or in a hall with line array speakers, then I wonder whether there really is spot on imaging at all! I have not experienced such. Yes, my live show experience reached upto A R Rahman and Indian Ocean (they to me are the most critical judge of their acoustic presentation of the lot I have heard).
Live programmes without electric/electronic support and performed at home are successfully replicated in my listening room with my OBs. I have some great field recordings.
 

yogibear

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WRONG!
The first thing that hit a properly seated audience by a well designed and placed OB is the precise imaging. Such is the precision that changing head position by inches changes imaging position by more than inches. That's how it should be as the wide stage is converging to a single point between ears. The difference of air pressures between ears need to be precise to have a sense of imaging to start with.

I have never heard someone speaking such thing about OB unless he/she has not heard a good one. But I have always read bad perceptions about OB, as very less have actually changed the perception with reality. Just because rear waves cancels front waves, it is not practically a low quality bass that OB generate, rather it avoid room impact a lot.

This, I am speaking from my 5 or so years of speaker design, study, pursuing others to listen to OBs. Omni speakers come very close to imaging of OBs, and are confirmed by Riley too with his comparison of Pluto and his Orion.

I request all to go out & listen to good OBs. The return on investment (DIY or straight purchase) is immense. My guess is, imaging of bass could be muddy if we use OB mid and cabinet lows, but I am not too sure. By the way, I have experienced imaging of bass too unless we talk about lower than 60~70 Hz. Others may disagree.

High Qt is not so important for mid frequency drivers. For playing bass, I think having greater SPL of LF drivers than the mid is more important than having Qt towards 1. It's a myth that drivers of 0.7~1 is a must for all drivers. How the whole system is synchronized is the first governing factor for performance. Ahuja drivers I use for LF have Qts of 0.54. they play superb bass.
Please do not think/perceive/design one item in isolation. Think of a system, think of the room too. Then the design will be the best compromised design and most economical.

My experiences have been very similar and I have been trying to put them in text.

If fact guys who used Qts >1 for LF drivers, preferred under Qts 1 drivers. A not so high Qts but larger cone area, high SPL and high senstivity drivers like even 100 dB are preferred for OB bass.

Imaging surely changes with position in my setup though I am yet to grasp the facts.

And YES, OB if done right, gives HIGHEST returns wrt effort, time and money. And to do it right is much easier than boxed speakers.

It’s not late BUT I really wish I had grown older making and breaking baffles instead of all those boxes !
 

prem

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Guys I have yet to hear anything that even remotely sounds like live.

Any OB that is have owned or heard does not sound like live :)

While OB sounds open as compared to a boxed speaker, the area that I found it lacking in was that it could not convincingly reproduce the ebb and flow of an instrument in a mix. As a result I never found it emotionally satisfying. This experience is obviously limited to only stuff that I have heard. There’s always the possibility that the systems I heard were never optimally set up:)

Every speaker topology has its own set of issues. At the end go with whatever floats your boat
 

yogibear

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While OB sounds open as compared to a boxed speaker, the area that I found it lacking in was that it could not convincingly reproduce the ebb and flow of an instrument in a mix. As a result I never found it emotionally satisfying. This experience is obviously limited to only stuff that I have heard. There’s always the possibility that the systems I heard were never optimally set up:)

Every speaker topology has its own set of issues. At the end go with whatever floats your boat

My efforts have been in this very direction, setting up it right. Just selection of right drivers does not make OB great but the line-up matters a lot. I think thats true with every setup.

One immediate effect of OB is sound is open, relaxed, effortless and transparent. And unfiltered FR drivers is the soul of my OB. I cannot make one without it. And I cannot listen to poor recordings on my OB setup, rather look for the best recorded stuff.

Another experience is: Its sounds amazing when I am seated in the front and NOT in any other room. Great boxed speakers, even the neighbors get to hear them and talk about.

However at louder volumes on my OB, neighbors do get uneasy.
 

prem

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Yogibear, that’s the first sign that it does not sound like live. Live music will sound good from any room:)
 

prem

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I guess OB is a great DIY option. Getting boxed speaker and horns right is not that easy in DIY
 

yogibear

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Yogibear, that’s the first sign that it does not sound like live. Live music will sound good from any room:)

Actually its similar to horns. I have been dwelling on this. It sounds realistic in the front but since I am using full range drivers with whizzer cones and these do 16-17K to about 120-140Hz and the LF driver takes up from 120-140 Hz down to 40Hz, the setup is not strictly dipole from 40 Hz to 16K but rather dipole from 40 Hz to about 3000Hz and above that monopole with kind of horn loading of HF (coz of surrounding larger cone of FR). No doubt at louder volumes the neighbors do complain as bass is dipole.

A strict dipole OB would be a 3 way with an extended range single cone driver and an open back OR something like vintage cone tweeter. Such a set up would surely sound more live and would be less directional. However here you lose the magic of point source reproduction in the front seat from HF to upper mid bass and invite headaches of CTC spacings.

Please correct me if my observation is not sufficient or flawed.
 

Hari Iyer

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@ Sumantha

I have to admit i have not heard any OB speaker till date other than yours - that too for not more than 15 min to 30 min. More over now memory does not serve well to form an impression. I will have to listen again may be with my reference cd to form some impression. In the meanwhile i am attempting a simple OB speaker myself after simulating them on Basta. Hope they are ready by end of month. Will let you know when.

About the imaging - are you saying that the imaging of the speaker should move along with your head? ie. when you swing one feet to the left or right the imaging should also swing along with your head? Please clarify as i am not able to understand this part. As far as my speaker is concerned they dont and are rock steady at the same point even you move 5 feet away.
 

sunder

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yogibear, in your speaker system, what is the gauge (AWG) of hook up wire & the main speaker cable? Which brand? Thank you.
 

yogibear

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Sunder, my cables are pure copper, soft and 16AWG both for FR and and 12 AWG for LF. Very common speaker cables.

I am not a fan of cables though there could be nuances of sonic impressions but I believe more in playing with tubes than cables.

The line-level cables are "Pro flex" brand from US and quite inexpensive. ($10 for a 1 mt pair)

I did my stint on DIY cables some 4 years back when I drew 92% 16AWG pure silver wire and plated it with pure gold and kept it in storage for 4 years only to find pin-holes in gold coating and discoloration due to oxidation of silver. I believe OFC copper of right gauge is the best bet. So called gold plated terminations/interconnects are actually rhodium plated. Rhodium has worse conductivity that copper but serves as an excellent barrier to oxidation to underlying copper and larger surface areas of contact compensates for the lower conductivity than copper.
 
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sunder

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Yes, pure copper is sufficient. Thanks for the videos. If you add a tube DAC or Tube Buffer, then the sound quality will be more warm. Nice set up :). Thank you.
 

yogibear

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Yes, pure copper is sufficient. Thanks for the videos. If you add a tube DAC or Tube Buffer, then the sound quality will be more warm. Nice set up :). Thank you.

Sound is nice and warm actually and I don't like rolled off highs. I think you missed to notice the Re084 DHT Tube Preamp in the line up. Anything else in line up will modify the actual sound. I like to keep things down to minimum and would do away with a preamp if possible.
 
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