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.

59843

59844

59845

59846

59847

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 :confused:

Sorry I couldn´t resist ;)

I am looking forward to more pictures.

[BMWCCA]

Hardly DIY then :confused:

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.
:applaud:

[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):D

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.

59850

59853

59851

59852

[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.

59843

59844

59845

59846

59847

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]

59880

59881

59882

59879

59883

[spkrman57]

Great project!

Ron

[ChitoBG]

Hardly DIY then :confused:

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.:D Edit: missed post 4

[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!


61452

61453

61454

61455

61456

[mbeards]

61457

61458

61459

61460

61461

[mbeards]

61462

61463

61464

61465

61466

[mbeards]

61467

61468

61469

[martin2395]

Oh my god, they are stunning :spchless:

[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.

[Mostlydiy]

Wow, just lovely!

/Mostly

[more10]

Beautiful! :thmbsup:/Mårten

[audiomagnate]

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.

Since this has now morphed into a marketplace thread, I have to ask. How much? Same finish, materials etc.

[mbeards]

Since this has now morphed into a marketplace thread, I have to ask. How much? Same finish, materials etc.


We were thinking along the lines of $12,000 Per pair for the unloaded cabinets. If we could get more going simultaneously, the price per pair would go down due to the increased efficiency of side by side building.

I Just got these speakers into my new apartment in Dallas and am setting them up currently with new simple crossovers with the advice of John Wolf from Classic Audio Loudspeakers. I will have more to come once I get some real listening time on them with the much more correct E145 woofers and crossovers.

[BeDome]

Oh my god, they are stunning :spchless:


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!

[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

[ivica]

We were thinking along the lines of $12,000 Per pair for the unloaded cabinets. If we could get more going simultaneously, the price per pair would go down due to the increased efficiency of side by side building.

I Just got these speakers into my new apartment in Dallas and am setting them up currently with new simple crossovers with the advice of John Wolf from Classic Audio Loudspeakers. I will have more to come once I get some real listening time on them with the much more correct E145 woofers and crossovers.
hi mbeards,
many thanks for the presentation of the fantastic project you have done.
I whish you to enjoy much listening them.
regards
ivica

[high sky]

I am so impressed with your project. I really love the design.

Could you bring a picture of them in your listeningroom. They do need some space, dont they.

Best Regards

[Eaulive]

I don't care if they don't sound so good (even if I'm sure they do ;)), the craftmanship is awesome... all the complex angles are a real work of art.
Bravo! :applaud:

[Mike F]

Very nicely done. Can you describe your upstream electronics and listening environment?

[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 (http://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

[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.

[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.

76400

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-express-speaker-l-pad-attenuator-100w-mono-3-8-shaft-16-ohm--260-261

8ohm: https://www.parts-express.com/speaker-l-pad-attenuator-50w-mono-3-8-shaft-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]

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

The veneer is movingui. I believe it is found in the African Congo. My friend Fred of Heartwood Custom Interiors had a large quantity stashed away for years waiting for a special project. He got it from someone who long since retired from professional woodworking. No doubt it came from a very old tree.

The finish was a custom mixed satin polyurethane stain with a few layers of clear over the final color. The entire internals of the cabinet were sprayed with clear polyurethane before final assembly to provide some resistance to moisture.

Thanks!

[Theopholis]

The veneer is movingui. I believe it is found in the African Congo. My friend Fred of Heartwood Custom Interiors had a large quantity stashed away for years waiting for a special project. He got it from someone who long since retired from professional woodworking. No doubt it came from a very old tree.

The finish was a custom mixed satin polyurethane stain with a few layers of clear over the final color. The entire internals of the cabinet were sprayed with clear polyurethane before final assembly to provide some resistance to moisture.

Thanks!


Well, looked it up on E-Pay and some other online wood stores. A 4 by 8 foot sheet was almost 200 bucks! I'd actually go for it, but it's not nearly as gorgeous as yours. They did have some very nice looking veneers, but they were limited to 7.25 inches wide. Maybe after I've veneered a few other projects, I'll think about buying the strips and joining them.

Enjoy your system!

[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....