[ttan98]

2007   Seas W26


2008  Tone Tubby and crappy sub

If I am not mistaken the TT on photo  is the 12" alnico version rather than 10" ceramic version. I believe the former is more expensive and sure sounds better.

[opnly bafld]

If I am not mistaken the TT on photo  is the 12" alnico version rather than 10" ceramic version. I believe the former is more expensive and sure sounds better.

I think it was the 12" alnico.

[panomaniac]

Thanks for the photo!  That's them.  I thought they were very nice.

ttan - yeah, sounds about right to me.  The TT might have been a bit "wooly" for my tastes.  Funny, 'cause I don't think I like lean sounding speakers.  Maybe I do.....

[ttan98]

Thanks for the photo!  That's them.  I thought they were very nice.

ttan - yeah, sounds about right to me.  The TT might have been a bit "wooly" for my tastes.  Funny, 'cause I don't think I like lean sounding speakers.  Maybe I do.....

Your OB 18" Paudio coaxial looks interesting indeed, I presume the sound would be lean and clean as well. I am curious about the compression driver you use, is the diaphram made from Titanium or some other material?, I find the titanium too gritty for my taste, with reference to the Selenium 220Ti. I prefer the De250 compression driver.

[ecir38]

If I am not mistaken the TT on photo  is the 12" alnico version rather than 10" ceramic version. I believe the former is more expensive and sure sounds better.

This thread has some info on the Lowther America OB.

http://www.diyaudio.com/forums/showthread.php?postid=1629625#post1629625

BR

[panomaniac]

Hey ttan,

I'm pretty sure the P.Audio CD uses a Titanium diaphragm.  But it's not bad, if you do the crossover right.  My Selenium D210t drivers are a lot rougher.  I think my Altec CDs have aluminum, they're nice.

I dunno - you can ask opnly bafld - he heard them.  Don't know if he liked the compression drivers or not.
When I 1st hear them, they would take your head right off!  But a few minutes of crossover work did a lot of good. Got pretty smooth.

[boudy]

... take a walk on the wild side... take out the copper inductors and resistors and let your 8" and 15" play "full-range" without any filters and see what happens... at the very least you might get a sense of the real potential of Open Baffle design to free your music from the constraints of what we think we know... or have been told to think... and what is actually possible.

15" and 8" drivers running full range...that's my dad's Magnavox console from the 50's, and it kicked. Unfortunately its long gone.

And those Maggie 6V6 PP amps have also come back around....

[-Richard-]

Hi boudy ~

That is exactly the audio system that Deborah's dad had in their house when she was growing up and developing her love for music... and she inherited that same "console" (everything in one cabinet with the drivers at either end, left and right) when she moved to NYC... and Deb still had it when we met many years ago... so I heard it play music many times and it was quite good.

I have since augmented the bass driver on my Open Baffle speakers... the Alpha 15A... with a simple coiled inductor with a value of .80 (I think) that cuts off all frequencies above about 1250 Hz at 6 db per octave increments. After about 1250 Hz the Alpha has a peak... which you can hear... so cutting it off at that frequency gives you a very smooth integration with the B200's... the result is a sound that is entirely seamless with a fully fleshed-out mid and lower mid range... fantastic for voice and instruments in that region... and this particular frequency integration seems to neutralize any apparent peakiness native to the performance of B200 alone.

I am now using a Heathkit 151A with a completely re-designed circuit by Sam Kim of Sam's Audio Labs in Canada... it is a 7 watt triode integrated design that sounds absolutely fantastic.

My father bought me (it was really for the whole family... but I took an active interest in it and bought the records and played them) a marvelous audio system when I was a young teenager... he worked in a factory 7 days a week (apparently without dad working overtime our family would not be able to meet our expenses) but he had a very refined taste for music (and theater and literature) and he secretly was delighted that I was so deeply interested in audio and music. At 12 years of age I was visiting the local audio shops in Brooklyn New York and listening to every speaker they had.

At that time the drivers were all mounted on a huge wall next to each other (you pressed a button to hear each speaker individually for comparison)... there was no baffle behind them... Open Baffle speakers!!!! When you purchased your system you also purchased a cabinet for it... there was no absorbent material provided for it or even suggested at that time... and that also was a kind of Open Baffle system... many baffle cabinets were even open in the back.

My audio system consisted of separate components... I had a tube integrated amplifier... I think it was a Bogen... and Wharfdale 10" co-axial speakers... the media was LP's... and the sound was glorious... those Wharfdale's were incredible sounding.

My current system is definitely out of that golden age in audio... audio has simply never gotten better than the sound it achieved in the 1950's... it all came together then (check out field-coil drivers for example).

So you are completely right, boudy... if you want to hear the most dynamic, alive, musical, fully textured, richest harmonics possible in reproduced sound... sound that rivals the real thing... then get yourself an EL 84 integrated tube amplifier and a pair of Open Baffle speakers and prepare (with a little care in component matching) to be stunned by what you hear... it will blow everything else away and expose the current scene in commercial audio for what it is... almost all hype and glitz... with very little real substance. You can spend a lot and get so-so audio... or you can spend a little and hear the best (build your own OB's for the fun of it and to save a fortune in speaker costs).

With Warmest Regards ~ Richard

[Magnetar]

I've had/built several EL84 amps and my favorite is still a bone stock (except the input jacks, hey, why change it if it sounds this good!) Grundig PP console stereo amp with telefunkens - 12ax7s as input drivers

It's psychedelic.....

Another good EL84 amp is the Gabe mod Magnavox console amp - Thermionic LSD

[scorpion]

I am a bit at loss here Richard, but I have been asked a question about the Alpha-15s in a mail, and I have to question your proposed crossover frequency at 1200-1300 Hz here. If you don't use any Zobel filter a 0.8 mH inductor would give you something like 4000 Hz 6 dB Low-Pass crossover frequency with the Alpha15 (and if you use a Zobel it will be even higher up). From my measurements that would probably be quite OK not changing much from the common knowledge that what is really dominating our impressions is response up to 600 Hz. And the lowest bass is not really counting until about 40 Hz here. Also I think that the Alphas and the B200 could complement each other beautifully because the precense build up in the Alphas is nowhere near their published response curve and the response could very well meet the rising B200. Now 1.8 mH would be feasible at 1100 Hz and 12 ohms impedance. Someone else should be confirming or denying this calculation about the crossover frequency ! 

/Erling

[pedroskova]

I've had/built several EL84 amps and my favorite is still a bone stock (except the input jacks, hey, why change it if it sounds this good!) Grundig PP console stereo amp with telefunkens - 12ax7s as input drivers

It's psychedelic.....

Another good EL84 amp is the Gabe mod Magnavox console amp - Thermionic LSD

...just swapped out the 12ax7's in a '59 Maggie console pull for some 'AT7's to level match between drivers - after a rough re-bias with parts onhand, they are totally transformed.

...gotta love the "seasoning" that different tubes afford.

[-Richard-]

Hi Scorpion/Eling

"I am a bit at loss here Richard, but I have been asked a question about the Alpha-15s in a mail, and I have to question your proposed crossover frequency at 1200-1300 Hz here. If you don't use any Zobel filter a 0.8 mH inductor would give you something like 4000 Hz 6 dB Low-Pass crossover frequency with the Alpha15 (and if you use a Zobel it will be even higher up)."

No Zobel is being used. I will have to check with PartsExpress to see if the .8 mH value is correct for the crossover I had in mind (around 1200Hz)... I had so many simple coiled inductors around that I may have wound up using this one by mistake. I will get back to you very soon with that information.

"From my measurements that would probably be quite OK not changing much from the common knowledge that what is really dominating our impressions is response up to 600 Hz. And the lowest bass is not really counting until about 40 Hz here."

I am not certain I understand your reference to "...the lowest bass is not really counting until about 40 Hz here."

"Also I think that the Alphas and the B200 could complement each other beautifully because the precense build up in the Alphas is nowhere near their published response curve and the response could very well meet the rising B200. Now 1.8 mH would be feasible at 1100 Hz and 12 ohms impedance. Someone else should be confirming or denying this calculation about the crossover frequency !"

I will check on your value of 1.8 mh... somewhere in the back of my mind it sounds right.

I looked up the word "precense" and could not find it in an english dictionary... what meaning does it have?

Always very nice to hear from you, Erling. Sorry for my slow response... I have been exceedingly busy lately. I hope you are well... I hear that Germany may relinquish the Euro... lots of fallout due from that.

Warmest Regards ~ Richard

[jeffac]

Hello Richard,

I assume Erling is commenting on the Alpha 15A cone breakup peak in its response curve at around 2 to 3 kHz, which from real-world measurements is nowhere near as pronounced as published frequency curves might suggest. And from a few of your descriptions of attempts to get the Alpha and B200 integrated to your taste, I have suspected that you have also been considering (adding) the voice coil inductance of the Alpha (0.84 mH) into some of your low-pass cut calculations. Correct me if you haven't. 

And I've followed your lead and that of Graham Maynard's "Spirit" speaker design in low passing bass drivers (twin Alpha's in my case) around the frequency both of you seem to have arrived at (~1100 Hz) to help flesh out the lower-mids of the B200 to correct for the rising response. With the Alphas in parallel (4 ohm) I've been playing with P-core inductor values of 0.56 and 0.68 mH. Both work OK, currently using 0.56 mH, and I don't notice any particularly nasty distortion emanating from the Alpha's. Maybe having 2 helps here a bit? I'm also playing with an alnico Saba greencone 8" mid and 4" tweeter on the same baffle, in an M-offset T-M arrangement above the bass drivers, flat narrow baffle. Purists will absolutely freak out at all the overlapping frequencies, nulls, phase inconsistencies, driver voice coil misalignment issues etc, but I'm going to persist with this for a bit because it sounds pretty darn good. The Saba mid adds a wonderful richness and it certainly doesn't fall behind the B200 in speed. However, early days and only a test baffle cobbled together with crappy plywood, alligator clip leads used etc. I have a way to go on settling on a baffle design that takes as many "OB good practice" factors into consideration as possible, but a great way to learn, have some fun along the way, and end up with that alive sound you always describe so eloquently.

cheers.. jeffac

[-Richard-]

Hi jeffac ~

Thanks for sharing your Open Baffle explorations... your present experiences are entirely synergistic to the theme of this thread... going beyond "hi-fi".

I really like your spirit of exploration... your willingness to actually "listen" to what your Saba experiments sound like... in spite of the non-text-book application of the drivers.

Perhaps the Saba is exactly what I am looking for... I would love to find an 8" Alnico wide-range driver with nice high-frequency characteristics to work with. I seem to lack the gene that would permit me to purchase anything from ebay. Somehow ebay and I are like opposite ends of a magnet... we seem to repel each other... that does not bode well for purchasing older drivers that would fit my criteria on-the-cheap.

These days things have to be really cheap for me to try them... I no longer have a budget worthy of the name.

Thanks for sharing your insights, jeffac... I really like the concise way you express your ideas... and you manage nicely to avoid the techno-speak language that seems to proliferate these days.

Warmest Regards ~ Richard

[scorpion]

Hi Richard,

I see I am inventing new words, presens it should be of course.
Jeffac is right in his assumption regarding my comment, it was directed to the Alpha cone break-up, which is not as severe as people might expect looking at
published frequncy plots. I think 1.8 mH would be a more appropiate value for your coil.

I will soon report on my latest OB, a 3 way passive with Alpha15s.

All the Best
/Erling

[-Richard-]

Hi Erling ~

Thanks for providing the correct value for the inductor crossover at 1.8 mH. I will also check things this week with Parts Express... I would guess that because I have a few inductors to choose from I inadvertently chose the wrong one... I deeply appreciate your astute observation and kindness in sharing your insights with me.

A passive 3-way OB... now that is something to cheer about!!!!!!!! How exciting!!!

It sound like you have been doing your Research and Development with precision... which is characteristic of your disciplined approach to design... I am very excited to see and read about your latest work, Erling. Solving difficult problems with simplicity brings one directly to the threshold of art.

With Warmest Regards ~ Richard