|Looking back, it's easy to comprehend why I'm a believer in the concept of thought as object - the notion that we bring into our lives that to which we give our attention. That's how I manifested many of the good things that I am fortunate to have this time 'round. But, sometimes I falter and forget that. I can be quick to immediately assume something is out of reach. That's exactly what happened last October when I learned that the speakers from the room I ranked best in show at RMAF 2005 were beyond my modest financial means. I managed a stiff upper lip and adopted a different, less optimistic kind of faith. Within a few days, they -- like many things that grab our attention and are pretty quickly released because they aren't that important to us -- would be but a faint recollection.
Not so fast there. Not this time. I was hooked. It turns out that I thought about them - a lot. And, believe it or not, I dreamt about them too. The amalgamation of deeply drenched tone, texture, nuance, dynamics, delicacy and drama that I stumbled upon in Denver was ostensibly not destined to become antediluvian history. So, let's begin with the cast of characters without whom the 604 Dream speakers would have remained just that.
- Pete Riggle (aka Mr. VTAF) for friendship, cleverness, competence, commitment, a great workshop, and a great stash of hard cider!
- Jay Fisher for the cabinet design and for being a great long-distance advisor. Jay's a quarterly contributor to the Robb Report and one of the artists and thematic designers responsible for the famous "The Dig" of the Atlantis Hotel on Paradise Island/Bahamas.
- Dennis Fraker (aka the Tube Wrangler) for showing me what this driver could do at RMAF 2005 in his Serious Stereo room.
- Bill Hanuschak of Great Plains Audio Inc. for a great product.
- Dan Babineau for some of the first capacitors to come off the Churchill line and Lenny Mayeux for a great conversation on the Blues; he and Dan are the founders of Running Springs Audio about whom you simply must read more.
- Steven King for sturdy and functional carbon steel stands
To get started, I decided to set aside some special time to humiliate myself.
Within three weeks of returning from the show, I began corresponding with Jay Fisher (who had been in on the initial design of the speakers in the Serious Stereo room). It started as a simple Email exchange:
Stephæn wrote: Just curious, how you and Dennis came up with the design ... having never built anything more than a birdhouse, I'm pretty clueless about all this.
Jay replied: The drivers are being re-manufactured with some real improvements by Great Plains Audio. I am using 1.5" Baltic birch plywood panels (super thick, super stiff and tonally great). I chose to use a mass-loaded transmission line because it is a great solution for the driver which has extraordinary bass for a point source. I have had great luck with this alignment in the past. There is a great DIY web site called Quarter-wave.Com created by mathematician/engineer Martin King. He developed calculation software for designing speakers with the MLTL alignment. The software was free and downloadable from the site. You enter the TS parameters for the driver and then the program allows you to explore various cabinet alignments. This is what was used to design the speaker. After completing my first pass at the design, I wrote speaker wiz Greg Monfort who has helped me in the past. He ran the Martin King program (and probably other ones too) and offered plenty of valuable advice. In my new pair, the driver is mounted on the wide side to allow the speaker to integrate better with the room by lowering the baffle step to inaudibility. Response will be smoother especially in the lower octaves and midband presence will be increased. I have changed/simplified the two braces that are in the plans I sent you, which is another important change. All of this will add up to improved sonics.
Okay, it sounds like English but I can't understand a word you're saying.
I was already fearful of asking another question. Looking at the plans, it was obvious that I was going to need to give this some thought - and perhaps more to the point, I was going to need considerable help. Plus, I needed to scrape up cash for the drivers. No drivers, no go. Next thing I knew, the holidays and New Year's had blown by. My next record on the topic is from mid February.
Stephæn wrote: Hi Jay, Pete Riggle and I were kicking back this weekend and decided that we're about ready to give the 604 project a whirl. I wanted to follow up with you to make sure you were still cool with me using the cabinet plans you sent, and, since I will need help, sharing them with Pete, my engineer. We plan to build one pair, spend some time with it in each of our systems and then decide what's next.
Jay replied: Very cool. It will be great to have another listener(s) of the design to compare notes with. I cannot give you guys my custom crossover design because I have an agreement with the designer that I would not. However, Iconic Manufacturing makes two excellent crossovers for the drivers. Iconic Manufacturing is located in your neck of the woods I believe.
Before you cut wood let's talk about the design. I have made some internal changes that you should be clear on since they will improve the sound. I have my pair assembled but one of the drivers was damaged in shipping so I shipped it back for repair and will have the speakers up and running very soon. The cabs are really big and heavy! Luckily in book-matched dark African rosewood, they look pretty retro.
Moments later, I get this email from Pete which Jay is copied on: Hi Stephæn, we need to do this project. I'm in. So is my shop. At my present level of understanding, I'd vote for going with the cabinet design Stephæn has actually heard and as shown in the plans versus the new version with the speaker on the wide face that Jay is speaking of. Advantages are, narrow frontal view makes it easier to get into room and Stephæn has heard it. I'm not sure I've got this all figured out. Let me know if I'm confused.
Stephæn wrote: Jay, thanks. We will be in touch before we cut wood! Pete, I'm ready to play. Will see about pricing on drivers tomorrow. Thanks, all!
And so, thanks to Pete's gallantry and generosity, it was set in motion.
"The point of living and of being an optimist, is to be foolish enough to believe the best is yet to come." - Peter Ustinov
Stephæn wrote: Hi Pete, I spoke with Jay this afternoon and he will let us borrow his custom xover. He also mentioned he bought his drivers from Great Plains Audio so I am going to try them, too, as they make the 704-8a for Iconic and as I understand it, have all of the original Altec machining and what not. I suggested a phone conference with Jay next time you are at my place. He thought that was a great idea. Much to discuss.
Pete replied: Thanks for all your groundwork. I've skimmed all of the emails you've sent on the project. Quality has a price. I remain in. One thing to keep in mind about the crossovers and cabinets is that you fell in love with a configuration you heard at RMAF. I really trust your ears and sonic tastes. I don't know how many times I've fallen in love with something, or someone, then chosen to change it or her, sometimes at considerable cost in time and money and aggravation and then found out that the thing I fell in love with was best left as is.
Might be wise to start with what you fell in love with. With Jay going to a new crossover design, maybe at some point he would let us try his old crossovers for a second opinion. Why did the Polish proctologist use two fingers? He wanted a second opinion.
Crossovers and drivers are sequentially the last thing we need to buy. First are the cabinets, then the drivers and crossovers. This allows time for others to give us reports on crossover experience while we craft the cabinets. And it delays our cash outlay, which is always good. We can start on cabinets as soon as we have settled on the configuration.
The fact that no one understands you doesn't mean you're an artist.
Things woulda, coulda, shoulda started to move pretty quickly from there. There was just one thing holding us back. Pete is a technical geek by nature and he just had to delve into the physics a bit.
Pete wrote: Jay and Stephæn, I'm relying on Stephæn's ears when he tells me that Jay's speaker design sounds good. I I trust Stephæn's ears. Other than the shape of the baffle plate, the box is intended to get the lowest octave out of the speaker. So I calculated the quarter wave frequency based upon the internal height of the box and got 71Hz. That made me think the system might be acting more like a bass reflex design. So I dug out the vented speaker alignment charts from Vance Dickeson's book on speaker design. I adjusted the Qts value upward to take account of the speaker being driven by a tube amp with a damping factor of about 10.
I found that this loudspeaker driver, with a Qts of .29, is a candidate for alignments known as SBB4, SQB3, and SC4. These alignments want a box volume on the order of 5 or 6 cubic feet, depending on the alignment. Required physical port lengths are on the order of xx.
Ohmigawd! See what I mean?
I could include many more of Pete's emails full of mental meanderings (it went on until May!), but Ill spare you. After receiving the above from Pete, Jay jumped in with a clarification.
Jay wrote: Hi Pete and Stephæn, I think I hear what you are saying and yes, you can get very close to the performance of my MLTL with a conventional bass reflex like the Iconic Stonehenge. However, my goal in this case was to go after the most linear, most natural sound possible with the most extended bass and to milk the driver to the last drop of its amazing 27Hz Fs parameter. (Actually there was one other MLTL alignment that would have been even less compromised with max flat response to 29Hz but it would be a 17ft² monster!) I guess I like my wife too much to do that to her. I chose the 10ft² alignment because its size was one stop short of completely insane.
I believe my cab sounds a bit more linear with tighter, more tuneful bass (and perhaps a bit deeper) than a conventional BR. The MLTL looks very much like a BR and it is vented similarly but, with the air column proportions and driver placement within that column, there is also some considerable transmission line action taking place. As Greg Monfort put it, "...this will be an MLTL, just not a 'forced' alignment like Martin King advocates. FYI, Altec recommended 9'3" and typically tuned them up around 45Hz to boost the mid bass a bit since vinyl didn't go very low but isn't the way to go if any source with much lower content will be used. Forcing an alignment with a pipe is for when you want to tune it well below the T/S max flat Fb .This means a much larger Vb so unless closet-size cabs are acceptable, high Vas and/or Qts drivers do not make good candidates for them. Martin King's work focuses on the smaller low QTS full rangers where the bass must be coaxed. The Altec 604 does not require this. I believe the Altec and JBL house sounds were rich in this upper bass region."
The bass in my MLTL should be pretty darn flat down to the 37Hz range with plenty of information clear down to 27Hz when corner-loaded or close to the back wall. If you have compared MLTL sound to BR, the difference is quite audible and even more so with smaller single-range drivers that are bass shy. With some driver's TS parameters, there are diminishing returns in going with the tapered MLTL. The performance difference between the parallel-wall MLTL and the tapered MLTL with these drivers is miniscule - and when you consider how much easier it is to build a rectangular cab, it's a no-brainer.
I think you guys should build one pair of BR and one pair of MLTL and then we will know for sure! The 604 driver is so killer. You would probably be happy with a little 5ft² box but why not go for Nirvana? It's what we are all looking for, ain't it?
"The basis of optimism is sheer terror." - Oscar Wilde, The Picture of Dorian Gray, 1891
Build one pair of each my ass! It was by now mid-March and we all got moving. Pete warned me that enclosure construction and weight with driver but without the required stand for the unbraced 1.5" thick Baltic Birch version will weigh in at 234lbs. If we built a braced unit with .75" thick panels and a 1.5" thick baffle, we'd be looking at 104 pounds. Then he asked a really good question: "How many more years will you and your friends be able to handle a 230-pound speaker?"
My back ached just thinking about that. In the meantime, Pete continued with his mad scientist ideas and computations.