My Hartsfield DIY Project

[mbeards]

Hi everyone,

So about two months ago I began probing the forums after being inspired to build my very own Hartsfields. I was asking questions about drivers, crossovers etc. I had very little knowledge about JBL product line, other than a few of the classic guitar and bass instrument speakers. Since then, I have learned a lot from everyone and continue to learn about the history and the JBL product line. The project is now well under way so I thought is was time to document the progress.

So way the Hartsfields?

Drawbacks? Many! Massive, heavy, expensive, dated, complicated.
Pros? Folded horn, dynamically revealing, powerful, JBL has the best drivers around, fantastic sound, and totally cool.

The main attraction for me was JBL's no compromise attitude in trying to blow Klipsch out of the water. JBL had the leg up, even though the klipshorn predated the Hartsfield, since JBL had the best drivers in the industry. This coupled with the best cabinet in the industry would surely be magic.

Second, I love the idea of high efficiency horns. Perhaps this is just the engineer in me, but minimizing driver movement while getting desired listening levels makes sense. I guess this is a little backwards from the initial days of horn speakers.

Volume level was the most desired characteristic, shaping the development of horn speaker systems. Theaters and stadiums needed louder PA systems and horns were the answer. Minimized driver movement was simply a side effect of the horn design. For me, minimal motor distortion and unparalleled transient response seems key for high fidelity; and are all benefits of a full horn system. That is if you can make a horn structurally sound, which does not add coloration. (Enter JBL)

For drivers the current lineup is: 15" 130A, 2441 Compression driver, 075 tweeter. I’m using JBL 3115 can N700 Crossovers (500 and 7000Hz), which I soon plan to rebuild with air core inductors and better caps.


The woodwork involved with these cabinets is simply staggering. Complex joinery, small pieces with complex angles, lots of fitting and gluing. Even using JBL plans in conjunction with CAD drawn plans, it is hard to wrap your bran around the project. Plenty of errors in both plans also help bring about headaches!

So... instead building it myself I have hired a good friend, Fred Goldstein of Heartwood Custom Interiors LLC, to do the building. His craftsmanship is second to none and attention to detail is spectacular, as I have come to know his work well over the years. I should also note that he has made small modifications along the way to better the design. For instance, the baffle for the midrange horn has been contoured to continue the shape of the horn, rather than leaving a hard 3/4" deep lip at the mouth. This kind of detail has been added everywhere in its construction.











For materials we are using mainly 3/4" Baltic Birch for all of the structural pieces and 3/4" medx moisture resistant MDF for large flat surfaces that are to be veneered. Joinery is biscuit-ed for pre aligning and added strength. Everything is glued as well as screwed together. They really are the nicest cabs around and much better than other repros or what JBL would have used at the time. No Home Depot cheap-o ply or cut and shaped 2x4's in this cabinet!

A good chunk is out of the way.

Next steps: Assembly of inner horn to outer cabinet. Caulk and smooth all facets and joints in the pathway of the bass horn. Then spray the assembly with black paint to smooth the wood inside of the horn pathway.


More to come,
Matt

[more10]

So... instead building it myself I have hired a good friend

Hardly DIY then

Sorry I couldn´t resist

I am looking forward to more pictures.

[BMWCCA]

Hardly DIY then

Sorry I couldn´t resist

Unless you create your own tools, or make your own plywood, or plant your own trees to harvest for the wood, everyone along the way has some assistance. I give credit for the idea and some of the grunt work.

[ChitoBG]

Hardly DIY then

Sorry I couldn´t resist

I am looking forward to more pictures.

"With a little help from my friends"

[maxwedge]

It's neat (awesome!) and all but please rotate your pictures. You know, it's kind of hard on the neck. Edit: missed post 4

[mbeards]

I originally planed the project to be a full DIY but with amount of wood working needed, a full wood shop is necessary. I don't think a table saw in my garage would cut it. (no pun intended)

Sorry for the rotated pictures, not sure why that happened!

I should also note that I repainted all the crossovers and added new mini 5 way connectors. Once They are up and running I will replace all the caps and inductors.

I also repainted the JBL 2310 pro lenses. These were fun! I disassembled the stack and sandblasted every aluminum piece. I didn't care for the black anodized finish and it started to flake off on the hard edges. I rounded off all of the hard edges and powered coated in a small oven one at a time. They came out great but it took a very long time.

[JUNGLECATGEORGE]

yep. i built my own hartsfields, but i have also build 4530 copys...way less work ,almost as good sound.take up a little less space

[JUNGLECATGEORGE]

man are them hartsfields heavy once you add 75 lbs of speakers.i liked my 4530's because the horns were in a separate box on top..way easier to move.i had to drag my hartsfields up stairs...wow.what a job to get them in the house..now the wife dont like the size.they are huge when they are all together

Hi everyone,

So about two months ago I began probing the forums after being inspired to build my very own Hartsfields. I was asking questions about drivers, crossovers etc. I had very little knowledge about JBL product line, other than a few of the classic guitar and bass instrument speakers. Since then, I have learned a lot from everyone and continue to learn about the history and the JBL product line. The project is now well under way so I thought is was time to document the progress.

So way the Hartsfields?

Drawbacks? Many! Massive, heavy, expensive, dated, complicated.
Pros? Folded horn, dynamically revealing, powerful, JBL has the best drivers around, fantastic sound, and totally cool.

The main attraction for me was JBL's no compromise attitude in trying to blow Klipsch out of the water. JBL had the leg up, even though the klipshorn predated the Hartsfield, since JBL had the best drivers in the industry. This coupled with the best cabinet in the industry would surely be magic.

Second, I love the idea of high efficiency horns. Perhaps this is just the engineer in me, but minimizing driver movement while getting desired listening levels makes sense. I guess this is a little backwards from the initial days of horn speakers.

Volume level was the most desired characteristic, shaping the development of horn speaker systems. Theaters and stadiums needed louder PA systems and horns were the answer. Minimized driver movement was simply a side effect of the horn design. For me, minimal motor distortion and unparalleled transient response seems key for high fidelity; and are all benefits of a full horn system. That is if you can make a horn structurally sound, which does not add coloration. (Enter JBL)

For drivers the current lineup is: 15" 130A, 2441 Compression driver, 075 tweeter. I’m using JBL 3115 can N700 Crossovers (500 and 7000Hz), which I soon plan to rebuild with air core inductors and better caps.


The woodwork involved with these cabinets is simply staggering. Complex joinery, small pieces with complex angles, lots of fitting and gluing. Even using JBL plans in conjunction with CAD drawn plans, it is hard to wrap your bran around the project. Plenty of errors in both plans also help bring about headaches!

So... instead building it myself I have hired a good friend, Fred Goldstein of Heartwood Custom Interiors LLC, to do the building. His craftsmanship is second to none and attention to detail is spectacular, as I have come to know his work well over the years. I should also note that he has made small modifications along the way to better the design. For instance, the baffle for the midrange horn has been contoured to continue the shape of the horn, rather than leaving a hard 3/4" deep lip at the mouth. This kind of detail has been added everywhere in its construction.











For materials we are using mainly 3/4" Baltic Birch for all of the structural pieces and 3/4" medx moisture resistant MDF for large flat surfaces that are to be veneered. Joinery is biscuit-ed for pre aligning and added strength. Everything is glued as well as screwed together. They really are the nicest cabs around and much better than other repros or what JBL would have used at the time. No Home Depot cheap-o ply or cut and shaped 2x4's in this cabinet!

A good chunk is out of the way.

Next steps: Assembly of inner horn to outer cabinet. Caulk and smooth all facets and joints in the pathway of the bass horn. Then spray the assembly with black paint to smooth the wood inside of the horn pathway.


More to come,
Matt

[mbeards]

[spkrman57]

Great project!

Ron

[Audione]

Beautiful work. You have definitely gone the extra mile with Baltic birch, expensive, nice to work with, smells good when you cut it. It is quite a project, I know as I have made in excess of fifty of these cabinets. The pair that I am completing in the next couple of weeks are veneered in koa and will be sent to San Diego. Very nice work.

[Audione]

I just read your choice of components. I was curious what made you choose a 130A?

[mbeards]

Hi everyone,

It has been a while since I posted on this project and I have had some very positive feedback from members.
The horns have since been completed and I felt it was time to follow up with remaining build pictures.


Enjoy!

[mbeards]

Hi everyone,

So I have been running this pair of 1959 spec JBL Hartsfields in Dallas for about two months now and I thought it was about time to write my opinion of these.

It took some tweaking and driver swaps to get them to the point they are at now but the efforts certainly paid off. The current driver complement is E145 woofers, 2441 midrange compression drivers, and 075 tweeters. I ditched the original JBL crossovers by first attempting to make my own complex autotransformer attenuated 3-way network with a low pass for the woofer, band pass midrange, and high pass tweeter.

With the advice from John Wolf from Classic Audio Loudspeakers (who has been selling some very nice Hartsfield reproductions for some time now), I moved to a much simpler crossover arrangement.

The woofer is directly wired with no crossover. As advised by John, the E145 will naturally roll off due to the cutoff frequency created by the bass horn. There is no need to force attenuation electrically.

The 2441 has a high pass filter with 12dB/octave slope crossed over at 500Hz. I used a capacitor in series with the driver so it runs flat out from 500Hz and up. A 16ohm L-pad takes care of the necessary attenuation.

The 075 tweeter has a 12dB/octave crossover set at 9Khz with a cap in series with the driver and a second L-pad for attenuation.

Moving away from complex JBL LX5 and N7000 networks was one of the best things going for these speakers. It opened up a new dimension. They have significantly more life and detail and feel more open and natural.

I have been running the speakers in this configuration for a while and I have been extremely satisfied with them. One of my biggest worries with this project was that the low frequency response would be restricted. Many people on the web warn of the Hartsfield limited low-end reproduction. With a pair of speakers this large, adding a subwoofer would take up that much more space. However, I am happy to report that the low frequency response is plenty low enough. I have yet to find any song in my collection that I feel is lacking in bass. Plus, the detail in the bass is unbelievable, adding to the depth and lifelikeness. My ears tell me that these go down to around 35-40Hz, which is perfect for most naturally produced bass frequencies…. maybe not ideal for home theater enthusiasts, but perfect for music.

I also love the midrange and high frequency detail these speakers achieve. Listening to some classic jazz records of Jimmy Smith, Stanley Turrentine, and Oscar Peterson, the solo instrument sits perfectly forward in the room with a staggeringly large sound stage.

If I had to sum up the JBL Hartsfield in a few sentences it would be that they exhibit extreme detail and nuance across the entire audible spectrum while still maintaining great amounts of musicality and lifelikeness. At the same time, they feel effortless and fill the room at low volumes without any feeling of constraint or forcefulness. It is just simply music filling the room without any perception of the loudspeakers’ existence.

Although I have had limited experience with electrostatic speakers, from my listening experiences they offer the same (if not more) detail than the Hartsfields but with a more sterile sound stage. To me I got the “wall of sound” impression from electrostatics, whereas the Hartsfields sound layered and full of life. Like I said, completely effortless.

This is the first speaker I have ever heard that if I close my eyes the band sounds literally in my room. I thought I have experienced this before with other speakers, but the Hartsfields proved me wrong!

Most recently, I had the pleasure of installing Truextent Beryllium diaphragms into the 2441s and the speakers made another leap forward in performance. An honest 100% improvement that was not subtle and easily obtainable by any listener.

The midrange horn seems to extend significantly lower than before, mating better to the upper range of the horn loaded E145. The upper registers of an upright bass transition from the bass horn to the midrange horn significantly better, giving a better sense of coherence. The lighter diaphragm also made a noticeable improvement in the transient response heard in drums and hard bass attacks. The midrange horn now truly matches the quickness and attack of the E145 folded horn.

The high frequency extension is also improved, giving greater detail to the click of a ride cymbal or the smash of a hard hit crash cymbal. Not only did the over presentation of sound due to frequency response improve but a significant jump in detail was also heard, putting these speakers miles ahead of electrostatics in my opinion.

If anyone is considering these diaphragms I feel they are worth the investment. The improvement is not subtle!

Anyway, I am extremely happy with these speakers and can’t think of a single system on the market I would rather have. Every time I use them I get as excited as the first day I first fired them up. The Hartsfields definitely needed some tweaking to achieve their full potential and in fact can be a bit crude sounding with the stock crossovers. …Especially as a two-way system. However, anyone who owns Hartsfields and are running them stock should consider these changes. There is a lot of potential here; it just needs to be unveiled.

Happy listening Y'all,
Matt

[robertg]

With the advice from John Wolf from Classic Audio Loudspeakers (who has been selling some very nice Hartsfield reproductions for some time now), I moved to a much simpler crossover arrangement.

The woofer is directly wired with no crossover. As advised by John, the E145 will naturally roll off due to the cutoff frequency created by the bass horn. There is no need to force attenuation electrically.

The 2441 has a high pass filter with 12dB/octave slope crossed over at 500Hz. I used a capacitor in series with the driver so it runs flat out from 500Hz and up. A 16ohm L-pad takes care of the necessary attenuation.

The 075 tweeter has a 12dB/octave crossover set at 9Khz with a cap in series with the driver and a second L-pad for attenuation.

How is this working for you? I built a pair of Hartsfields last summer and I am running active crossovers with three amps. I'm thinking of changing to just a single amp to simplify things.

To accomplish what you did, do you just use a capacitor in series and then an inductor in parallel, followed by a l-pad for both mid and high? I found information online for the values of the inductors and capacitors for the desired crossover points. I'm assuming I should use 8 ohm l-pads because my drivers are 8 ohm? What about the wattage of the l-pads, is higher better?

I'm running 130A low, 2446 mid, and 2402 or 2404 tweeters. Can't make up my mind on the tweeters yet.