My Hartsfield DIY Project

[mbeards]

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.

Great to here there is now another m with a pair of Hartsfields!

My crossover is extremely simple. I have attached a drawing of the schematic.



I use a 16ohm L-pad for the midrange and 8ohm L-Pad for the tweeter both from Parts express.

16ohm: https://www.parts-express.com/parts-...6-ohm--260-261

8ohm: https://www.parts-express.com/speake...8-ohm--260-252

I removed the original JBL autotransformers from the crossover plates and mounted these with the JBL knobs for a factory look.

My final driver lineup which I have been running for the past 2 years is:
TAD 1603 woofer 8ohm
JBL 2441 16ohm compression driver with Truexten Beryllium diaphragms
JBL 2405H 8ohm sitting in mount on top of the cabinet

• The impedance mismatch with the 2441 may seem odd, but the higher impedance helps knock down the efficiency a bit compared TAD 1603 so I can use a little less attention in the L-pad for the mid-range compared to running all 16ohm drivers. The net impedance curve is very kind on amplifiers and is very flat at 7-8ohms.

• No doubt the TAD 1603 is the best 15” woofer I have ever heard. It excels in this cabinet compared to the E145’s I was using. With the speakers placed near 2 symmetrical corners of my listening room for room gain, the speakers are roughly -10dB at 30Hz! Keep in mind that this bass is extremely accurate, and miles ahead of any subwoofer on the market.

• Also, I would recommend the 2405H tweeters based on my experience. I get superb imaging through the entire bandwidth with this arrangement. Female vocals never sounded more real. Dianna Krall’s “I don’t know enough about you” sounds like she is in the room singing since the sound field of her voice is roughly the size of a human head in the center of the room.

BTW if anyone is in the Chicago area and wants to hear these, my door is always open.

-Matt

[robertg]

It's funny you replied to this today, I just ordered parts to make a crossover. I believe these are first order crossovers, 6db/octave? I'm going to go with second order, 12db/octave. They have a capacitor and inductor. Building a crossover can be extremely complicated, and I know just enough to be dangerous.

I have a DBX Driverack now, so I can control everything. My ear can't hear a difference when I make major changes. If I change the woofer and mid to roll off early, or run flat out, I can't tell.

[Theopholis]

Absolutely gorgeous. I didn't see it in the thread. What wood veneer and stain did you use?

[mbeards]

[mbeards]

[mbeards]

[martin2395]

Oh my god, they are stunning

[Lee in Montreal]

Definitely impressive. I am pretty sure they even sound better than the orignal as you have much improved on the quality of woods and the structure. Great work.

[JBLP]

My compliments!!! What a nice craftsmanship and finishings.
And I really like the workshop!
They get a good home?

[mbeards]

Yes these will get a good home!

I am in the process of moving so they are stored until I have the setup ready for them.

As others have mentioned, the quality of the build and the materials available today blows anything JBL could have built out of the water. Even many of the other reproductions are using poor quality materials which all effect the sound quality of a folded horn. I was actually considering reproductions from one of the available builders for a while, but after seeing build photos, I wanted to control the quality of materials. No cut down 2x4's in these!

If you want historical value, buy the originals. If you want the best sound quality, get these!!

If anyone one is seriously interested in purchasing a singe or pair of these cabinets, please send me a private message. We would love to build more for others but it only makes sense if we have a couple of orders. This was we can do more and parallel and reduce the costs for everyone. They would be available with any wood veneer and any finish or color.

[mbeards]

Thank you everyone for your comments!

As for my electronic components:

VPI Scout turntable with a Soundsmith Zephyr moving iron cartridge
ProJect Phono Box S phono preamp
Project Pre Box S Preamp
As for amplifiers: I design my own. I am a trained EE with an analog design background. I started building tube guitar amplifiers then moved into HiFi amplifier design. I don’t intend for this to be a sales add but please visit www.bandwidthaudio.com for more information on the amplifier I am using.

The weakest link in my system is now my room:

I finally purchased a calibrated measurement microphone, which I use with Room EQ Wizard. I first realized that I was not getting the high frequency extension I wanted so I changed the crossover by strapping the tweeter L-Pad to the input of the speaker rather than off the already attenuated midrange horn.

However, with the high frequencies now measuring flat past 20KHz, the stereo image began to blur. I think the reason for this was due to mounting the tweeters in the pockets of the bass horn mouth, which puts the tweeters far off axis. Also my measurements hint at some lobbing at specific frequencies due to reflections off of the top of the cabinets and exit of the bass horn. (I would imagine that the Paragon suffers form this badly since they are mounted way into the mouth of the bass horn)

To fix this I ended up adding 077 tweeters on the top of the cabinets in a small cradle. Now there are minimal reflections and they are on axis with the rest of the system. The tightened the stereo image back and gave the high frequency content I was missing. Note: Keeping 10KHz to 20KHz flat really does make a huge difference! Everything opened up compared to the old 075 setup and I get the breath in well-recorded vocal tracks.

It is also amazing how much high frequencies change the perception of bass frequencies. For instance, the imaging of upright or electric bass is much improved since all of the cues (like fret buzz and clacking) help track the spatial location of the instrument in the room. Since low frequencies do not have strong directionality, the sense of location only comes form the very high frequencies produced by these instruments.

Lastly after much listening I swapped the JBL E145s for TAD 1603 woofers. These increased the bass weight slightly and improved the low frequency response. The bass is a little less fast but I think overall better rounded with a less “honky” feel. I think the E145 loses efficiency shapely below around 40Hz reducing the output and creating a slightly honky feel.

With these changes I am finally done with the speakers! My measurements show my room is the next challenge. There are lost of modes at low frequencies causing very uneven response. There is a fairly large null/roll off at around 40Hz in my listening position then a large constructive node at 30Hz causing a very sharp peak in the response.

I know these nodes don’t help my impression of the E145, but the TAD 1603 certainly works better with my room as it stands now.

Cheers,
Matt

[BeDome]

Oh my god, they are stunning

I am amazed and envious, but WOW!

[tomee]

Wow!! Beautiful work and outstanding final product!!! Although these are currently out of my league, I don't find the price out of line for what's being delivered.

[Val]

Thank you for taking the time to document this project!

[patallen]

hi, sorry i know this thread is old. i try to read all i can about the Hartsfield speaker to understand it the best i cani collected a lot of pictures from various forums on internet. one thing id like to know is if there is any stuffing/pading in the horn path itself, i saw in some cases on original cabinets some visible pading on the front cover where there is a V that direct the wave on the sides....am i wrong ? visible when the woofer itself is removed looking up front id say...(see picture)I made some prototypes of this speaker and found that there are very nasty resonances at 100hz and 200hz.horn lenght and calculation suggest a close match to a 50hz wavelenght...so basic harmonics should match.... pading in there must help i guess.any improvements you made on yours ? you mentioned it didnt sounded as good as you wanted....thanks....