DIY Yorkville U15 clone (Unity horn/multiple entry horn)

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I'm seriously considering cloning the Unity half of a Yorkville U15. This is for outdoor PA use, not home hifi.

For those who don't know, a U15 uses a 15" driver for the low end, and a 15" conical multiple entry horn for the mids and highs. The horn uses 3 mids (5") and 1 compression driver. Yorkville dealers will sell the horn, mids and compression driver by themselves. Cost will be about $700 for the pair.

I have the following questions:

  1. Does anyone have a schematic for the crossover circuit? GOT IT!
  2. Does anyone know the crossover frequencies and slopes? GOT IT!
  3. The U15P has a digital crossover/dsp. Any info on its crossover points, slopes, and notch filters? GOT IT!
  4. Is there a compression driver cheaper than the specified BMS 4550 that would be suitable? They're ~$170 (each), so it's about half of the cost for this project. I'll be using DSP so it doesn't have to be a perfect match for the BMS 4550.
  5. Has anyone done this project? It seems like the easiest way to get a pair of multiple entry horns going on a budget.
 
Last edited:
1) The schematic for the crossover circuit and parts lists are in the service manual:
YORKVILLE U15 SERVICE MANUAL Pdf Download.
2-3) The various crossover frequencies and slopes can be inferred from the "U15 Analog.ATS2" chart also in the service manual. Plenty of EQ used!
4)Any different drivers would require a different crossover design.
With the approximately 24dB/1200 Hz HF crossover used, there are certainly cheaper drivers available that could work, though doubt you'd find any that would work as well as the BMS driver the system was designed around.
Assistance Audio might have better BMS pricing than Yorkville.
Jack Arnott, owner of AA frequents DIY.
5)Most have found used U15s the "easiest way to get a pair of multiple entry horns" rather than buying them "one piece at a time" ;^).

Art
 

Attachments

  • U15 Xover.png
    U15 Xover.png
    122.6 KB · Views: 930
Last edited:
Many thanks! I'm so surprised that the manual has the complete crossover circuit. That's a pretty wild EQ. At this point I think I'll probably just do it with DSP using an RTA mic for guidance. It'll be simpler than building a physical crossover and it'll open up the possibility of using a cheaper compression driver.


I checked Assistance Audio and it was only a few dollars cheaper for the BMS 4550.


Haha, yeah, I'd buy used if it were an option. I live in an extremely remote area so it's fairly unlikely. I do check ebay, but there's none for sale.
 
For hifi use, Bill Waslo's Small Syns are hard to beat. Here's why:

4088257133_44dd20fa26_o.jpg


As I understand it, the Yorkville Unity was designed by someone at Yorkville and they licensed the technology. No idea if the license was from Sound Physics Labs or Danley Sound Labs. I'd assume the former, since they had the (now expired) patent.

So, the first strike is that Danley didn't do the design or the crossover.

The second strike is that conical horns exhibit an on-axis dip due to their symmetry. That's why JBL, QSC, 18Sound, etc, they all use asymmetrical horns.

The third strike is that there's no roundover on the horn. You really want a roundover, it makes everything better. Frequency response, imaging, etc. It's a no-brainer.

The fourth strike is that BMS 4550. That's a lovely compression driver, but you're right, it eats up half your budget.

Bill's design is smaller, it costs less, the compression driver is a third of the cost of a BMS 4550, it's horn is asymmetric. The only downside is that the waveguide is no longer available AFAIK. :eek:
 
I have U15 but I didn't spend too much time on them right now because I miss time but I can say that from what I've heard I must agree with Patrick. There is a problem with the design himself and the crossover. It is easy to detect just by ear. The crossover and in the delay they used (I have the passive version) are wrong. I'm not sure I'll spend too much time on them , because I wanted a ''hifi' loudspeaker. I might sell them for this reason.

By the way they sound big and I'm sure for a PA used there are okay
 
The only downside is that the waveguide is no longer available AFAIK.

I appreciate the reply. I can't argue with any of that, but with the SEOS15 waveguide NLA, it's irrelevent.

I asked Erich about that -- his reply:"
I've never told anyone that they were no longer available, so that seems strange. I've told people that the ones I currently have are allocated
to the kits but that I would be getting in more soon. I don't mind you telling people that.

So -- the SEOS15 IS still available (but may take a few weeks to get at the moment).
 
Update: I bought a pair of U15 :)

This project was largely put on hold the last few months. During that time I considered several approaches:
1). A quad-amped system without a passive crossover. (Subs, lows, mids, highs). This has the advantage of maximum flexibility. The drawback is that I don't have enough amps for that, and if I did, it would be housed in an annoyingly large rack.

2). A tri-amped system with a passive crossover on the mids/highs (the Unity horn), and the subs and lows crossed over with DSP. This seemed like the best way to go until I looked at the schematic for the U15. I didn't price it, but duplicating that crossover would be prohibitively expensive, I think, and also might be above my ability to build and troubleshoot.


I looked into class D boards for powering this. Most of them seem pretty squirrely. The exception is the Ice Power amps, but those are priced pretty high for what they are. If products like MiniDSP and Ice Power were cheaper, I would have used modules like that for this project. At this point they are too expensive for me so I'm sticking with Inuke amps and DCX2496 DSP.

Meanwhile I stalked ebay for U15 speakers, and last week I won an auction for a brand new pair. They sound fantastic!

Some friends-of-friends want some horns like these, so if they'll build the crossover then I'll build the speaker cabinets. If that happens I'll update this thread, otherwise that's all from me.

Thank you all for your help!
 
Last edited:
I know we're supposed to DIY here, but something like the U15 is very hard to out-do at about $1000 each brand new. I got the best of both worlds: a few years ago I took a chance on a trashed pair of U15, the shipping was about as much as the sales price, but about 1/3 of new, delivered. Gutted them, including passive EQ. They are active EQ-ed and powered by disreputable Behringer electronics :) With active tweaks (REW and limited testing) they are dialed in as best they can be. They are easily the best sounding speakers I've ever owned. They will do until I buy a pair of Danley SH50. These are for home use, but I see no reason they couldn't be used for gigs?
 
Yorkville U15s are the real deal!

Hello fellow audio enthusiasts! I am a life long audio engineer, musician and audiophile. I have been silent until now.

First, let me say that I too am addicted to good sound and while a lot of us have many opinions about what good sound is, I'd like to share a philosophy about it that many people ignore, or are in denial of, and, hopefully, inspire the same simple understanding of what it takes to achieve it very affordably and sensibly.

I have posted here on the U15 thread, because that's where my journey ended. Seriously… ended. They are as good as it gets. Which you'll see on the graphs later in the post.

Elements of a good sound system in order of priority;

1. Room Size and Acoustical Treatment (.6:1:1.6 proportional ratio) Preferably Real Traps Bass Traps. [No they don't just trap bass! The acoustical coefficient of the material is like magic.]

2. Reference Source Recording with proper dynamics (none of this squashed for iPod crap) I am starting a YouTube channel soon to illustrate how the audio manufacturers have duped the majority of consumers with their 24bit/96k nonsense. When most releases coming out of mastering facilities [since about 1991], due to thinking if they go against the masses to defend dynamic range, they won't get work. 24bit has nothing to do with frequency response. It's about dynamic range. And if your music has no dynamics because of how it's been recorded and mastered, then you may as well stop reading this.

3. Good quality (uncolored) preamp. [A preamp should not have its own sound. Its job is to let the source flow through it without changing it. It's a source selector-volume control. That's it - nothing more.]

4. Full range speakers and subwoofers. You MUST get the mud frequencies off of the low-mid woofer/driver to eliminate intermodulation distortion in the low mid bands. Period. [This is not negotiable unless you're lucky enough to own a pair of JBL L 250s.4-way speakers designed by Greg Timbers from JBL]

5. Good (fast) Amplifiers for Mid-Hi Cabinets and Good Amplifiers with High Damping Factor or good Back Emf control of cone movement of subwoofers.

6. Calibrated Mic and REW software or equivalent to measure and prove what is happening in the room and make adjustments to strive for a flat response with good control of decay. [Shown in graphs below.]

7. Reasonable listening distance and equilateral triangle between speaker spread and distance to your ears. We are attempting to recreate the recorded performance and the musicians were not sitting in your lap when they placed mics and created the recording nor were they recording in a giant living room with poor reflective surfaces. Your experience is only as good as the weakest link. There isn't a speaker you could spend enough money on to compensate for a poor room.

So, here's my system utilizing Yorkville U15s. I leave some brief comments behind each component and let the graphs speak for themselves.

Mid-Hi Speakers: (2) Yorkville U15 Passive Three-ways. Yes I know people think Tom Danley designed them. He didn't. The summation technology was licensed to Yorkville and the U15s were designed by Todd Michael at Yorkville. The magic in these cabinets and drivers is that the summation makes the crossover point between the mid drivers and compression driver indistinguishable - even off-axis. And the dispersion is smooth and far because the horn is conical. 60˚ is PLENTY in the listening position. The driver selections and summation time alignment make the horn NOT sound like a horn. Yet, the horn makes it come alive at low power levels and bring the dynamics into focus as a result. You U15 owners who have stated that they need a phase plug? Nonsense. It's your room causing the issue. As you'll notice by the graph, the high end has extremely flat response with little deviation due to the room being treated correctly. As far as the low-end performance goes, they are designed to be used with subs. that why they naturally roll off at 50Hz. Don't run them full range, They are not meant to - so stop comparing them to speakers that claim better low-end. then there's the question of: Can a PA speaker be used for Hi-Fi? The only reason Pro speakers and Pro amplifiers are classified as PA is they are rugged enough to be thrown around night after night. That's it. It's up the manufacturer to put into that product(s) to fetch the price a market will pay for them - and this U15 my friends is a GEM! If Yorkville made them with solid walnut and pretty grill covers, they'd be in your living room!

Subwoofers: (2) JBL 4641s. Don't get me started on ported vs. sealed. Those who pontificate on accuracy and chuffing like to act is if people sit in front of their woofers and listen to steady explosion sounds at full volume with no dynamics and act is if that's the same as music. And most of those are listening to music that was mastered horribly and completely out of balance with the high frequencies. See, you got me started! Bottom line - these JBLs don't chuff and extend to 20Hz WITHOUT DSP! VERY Efficiently I might add. And when they do that efficiently, there is no chance ever of a chuff and no need to be sealed. Here's the key: To recreate instruments with large diaphragms. Use large diaphragms.

Preamp:Bryston BP20. (This is one of the cleanest and quietest preamps for the money you'll never hear. That was meant to be thought provoking!)
Active Crossover: MiniDSP 4x10 Hd - Crossed over at 70Hz at 24db/Octave - NO EQ Active.

Subwoofers Amplifier: Crown K2. Best amplifier for bass on the plane(t). No fan noise and proper damping to keep the JBL 4641 drivers in check.

Mid-Hi Speaker Amplifiers: (2) Sanyo Plus P55s bridged mono [200W @ with 3dB Headroom!]. These amplifiers are the best kept secret most ignore just because it says Sanyo on them. If you do your research, you'll see not many amps even come close. Plenty of head room and the Slew Rate goes to 300V/usec! That's fast for crisp, accurate high end. And, since the U15s are so efficient, I haven't even come close to clipping them even at ear splitting levels. No I don't listen at ear splitting levels and my hearing is perfect even at 53!

Digital to Analog Convertor: Bryston BDA1. The absolute perfect DA. Balanced out into the Bryston BP20. A match made in heaven.

CD Player: Denon DN-C640. The most beautifully simple, elegant and modern player/transport for CDs. SPDIF out into the BDA1.

Phono Pre-amp: Project Phono Box RS. Transparency, versatility and balanced outs. Enough said.

Turntable & Cartridge: Technics SL1200 mk. III and Sumiko Blue Line No. 2.

Spectrum Analyzer: Audio Control 3050. Helps educate listeners as to what they are and are not hearing.


Reproduction of recorded sound is all about doing it with the least amount of effort possible. Effortless sound is the most musical.

So here's the frequency graph;
An externally hosted image should be here but it was not working when we last tested it.


followed by the waterfall graph;
An externally hosted image should be here but it was not working when we last tested it.


Picture collage of my listening room (taken a while ago while doing some improvements);
An externally hosted image should be here but it was not working when we last tested it.


Thanks for reading and enjoying this stuff as much as I do. Feel free to ask any questions. It's great to be a part of this community!

And, If you're ever in the area, I invite you to stop in and hear what you've been missing!

Brad
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.