Another OCD build

[ocdSCHACK]

Re: Another OCD build

I've been out of town and haven't been on here a while. I really appreciate all the comments, so thanks to all of y'all. The final crossover I chose skips the first cap on the tweeter x-over and uses an 8ohm resister. Skipping the first capacitor really smoothed out the tweeter response, but also it played with the amp's emotions. This type of x-over on the tweeter wants a 12, or even better, 20 watt resistor. Using a 10watt at loud levels, I kept waiting for a fire to start from the heat coming off it. I also tried the same crossover with the dome version of the XT-25. It measured as smooth or smoother, but lacked a certain clarity the nipple version has. It's weird, the "dual ring radiator" added more clarity, but I didn't hear much more hiss or recording problems that more revealing speakers usually provide. The dome version made them sound more like old school McIntosh speakers that sound almost muffled when compared to speakers made today. It's all personal preference, but I liked the revealing XT25-TG30 better... especially when $hitty recordings didn't really sound any worse.

Honestly, I'm not trying to be "that guy" that loves his designs, but if you actually adjust the placement of these, they image exceptionally well. Of course some recordings are better that others, but here's what I found listening to one song.
The method: close your eyes, spin in circles, point to sound you are focusing on...
In this song, I could hear 3 things that really stood out:
1) a Drummer
2) a Guitar
3) a Singer
After spinning around with my closed eyes, I pointed to where each musician was sitting in relation to the lead vocals.
1) Drummer- Left side of the room. Turned out to be very close to the left speaker's placement.
2) Guitar- Mid to right side of the room and behind the singer.
3) Singer- In the center in front of me, which was dead center of both speakers
I give more credit to the tweeters than myself, but I do promise these speakers image well.

[classicTEK]

Re: Another OCD build

Really Nice job on the design. EXCELLENT work!!

I am getting ready to put together a set of Peerless 830875 & Vifa XT25 for a two way combo. Looking forward to it!

Do you have a pic of the back of the crossover boards?

Cheers

[mgrabow]

Re: Another OCD build

nice build, great photos...

[2leftthumbs]

Re: Another OCD build

The neo xt tweeter is on sale,too.

[ocdSCHACK]

Re: Another OCD build

Just another update... I love these things. I'm delaying their departure, but am ready to build another pair. Anyone who's looking for a smallish pair of speakers for a small room...this might be them! They play sounds to almost 20Hz with an F3 of about 40-50Hz in a small room;) Either the quality of the tweeters, or my particular x-over design, may hurt their sound at 10,000Hz+. They might be too high for less-than-optimal recordings or children with great hearing.EDIT: I don't find final crossover version to be harsh; that comment was referring to the initial crossover I was working on. I'm debating a clone of this build with cheaper tweeters, but I must say...these HDS drivers are awesome for those that don't, or won't, play music at really loud levels. I'm ready to build another pair for myself with cheaper version of the same tweeters and a front port to help minimize the near wall sensitivity.
The two musicians (a guitar/bass guy and a drummer guy ) I played them for said:
1) How much to build another pair using two woofers? They sound awesome, but we should build them bigger and maybe add a sub later, if we need it."
2) The drummer, who heard them in my apartment, which is a smaller area, said " I wouldn't change anything. They sound so even. They sound so neutral."

P.S. I'm only writing this because the woofers are $30 right now, a cheaper version of the same tweeter might cut down at 10Khz+ for those with younger ears, and I'm ready to build another pair for my lonesome.

[ocdSCHACK]

Re: Another OCD build

Here's an update/ some tips that may be useful for others.

For the crossover, I used Radio Shack European style terminal strips that were cut in groups of 2 and 4. I used heat shrink tubing to separate the + from the - terminals as seen here:


The heat shrink was cut to size and placed on the terminal strip.



Then, I heated them for a tight fit.


I used a super expensive "flat nose" pair of pliers to straighten the ends of the resistors, capacitors and inductors. They were $199.00 from www.ripoff.com. Oh wait! They were $1.99 from Harbor Freight. They are great for removing bends and crimps in wire.


I used them for straightening and making sharp turns in the wire to keep the crossover clean. The clean layout has no audio effect but, I had to test my ability to build an OCD crossover. If I did it again, I would've used a circuit board over a scrap piece of Hardboard.


Another pic "in the process"


Here's the x-over layout: (note that the tweeter is reversed) EDIT: The new crossover has changed for the tweeter part. The first capacitor is omitted and the 4ohm resistor is now 8ohms. Use an 8ohm that's higher than 10watts...it can get really hot if you play them loud.


And here's the frequency response. The response below 100 Hz is excessive because of the near wall placement. Changing the placement will flatten it.


Here is the final crossover: I don't think I have a pic of the final frequency response, but my ears liked this version more.

[ocdSCHACK]

Re: Another OCD build

I doubt there's anything major, but I would guess... The smaller the driver, or the thicker the baffle, the more problems you would get. If you worry about driver alignment, it also works in the wrong direction. Some people will move the tweeter back, so the woofer's center is aligned with tweeter's center. But with all speaker building, it's a compromise. You have to choose what's important, and what's overkill.

[emilime75]

Re: Another OCD build

I've been wondering about rear mounting woofers for a while now and had concerns if it would effect sound quality in any way. Are there any pros and cons to the method, as far as sound quality goes?

[wyomingbob]

Re: Another OCD build

"I have FRD's and ZMA's for anyone willing to help. So far for crossovers, I've build 2 opposite extremes and confused myself on what I should go for. "

Howdy,

I ordered a pair of those 831735s for a first-time project with Dayton DC28FST-8 1-1/8" silk tweeters -- likely to be an MLTL or one of the Chang BVR series with a 2k 24dB crossover. Have been trying to use one of those crossover design worksheets, but figured out it needs specific FRD & ZMA files.

I'd appreciate if you could e-mail a copy of those files <[email protected]> and I'll let you know how the design works out....I've wired operating controls in oil fields and on a 10-story coal loading tower, but crossovers are a whole new challenge for me.

[ocdSCHACK]

Re: Another OCD build

It's always good to know the final application when voicing/crossing over .. I'd just set it up so you can meet the guy and learn where he'd like to put the speakers. He may put them in a large room (if he's wealthy, he's probably got a lot of large rooms) or he may shove them against a wall. You can't know until he's got them.

That's what I was thinking, but it's doubtful I'll meet him. I think I'm gonna have to send a paper with the speakers on how to place them for his tastes, or in other words, how to avoid making them sound awful. They sound good to me and I've switched the x-over too many times to count. I eventually convinced myself he won't attempt to blare them at concert levels, and I should be more objective with my listening. In anything similar to their current placement, I feel pretty confident they'll meet his needs.

By the way, is that picture by your name really you? If so, we're bound to have some mutual friends...assuming we didn't already meet in jail one night.:D EDIT: I'm not trying to sound "gay" or be an as$hole, but that picture cracks me up and reminds me of what my friends and I looked like every morning in college.

[ocdSCHACK]

Re: Another OCD build

Hello,
I would be happy to fiddle with your .FRD + .ZMA files and model your crossover, see if I come up with any suggested changes? Did you measure the woofer impedance in box?

A resistor in series decreases efficiency, not increase. The resistor simply converts electricity to heat....

Please add at least one brace, or a cross brace. Your walls are fairly thick, should be good for the bass.

How about lining the walls with fiberglass or some other fiber material? Listen both ways and see which you prefer? (A small amount of stuffing (such as lining the walls) will make the inside of the enclosure more "dead" - interior midrange frequencies bouncing around inside the cabinet will attenuate faster...


Plywood is particularly good for screwing, as you noticed [big adnvantage over MDF which is bad for screwing].

I actually have the crossover done pretty well now... I would just prefer more efficiency. PM me your email and I can send the files; it can't hurt.

[MSaturn]

Re: Another OCD build

It's always good to know the final application when voicing/crossing over .. I'd just set it up so you can meet the guy and learn where he'd like to put the speakers. He may put them in a large room (if he's wealthy, he's probably got a lot of large rooms) or he may shove them against a wall. You can't know until he's got them.

[critofur]

Re: Another OCD build

Hello,
I would be happy to fiddle with your .FRD + .ZMA files and model your crossover, see if I come up with any suggested changes? Did you measure the woofer impedance in box?

A resistor in series decreases efficiency, not increase. The resistor simply converts electricity to heat....

Please add at least one brace, or a cross brace. Your walls are fairly thick, should be good for the bass.

How about lining the walls with fiberglass or some other fiber material? Listen both ways and see which you prefer? (A small amount of stuffing (such as lining the walls) will make the inside of the enclosure more "dead" - interior midrange frequencies bouncing around inside the cabinet will attenuate faster...

I thought I would need to clamp it initially and did plan to go that route, but when I tested with the screws I used, it was sturdy...

Plywood is particularly good for screwing, as you noticed [big adnvantage over MDF which is bad for screwing].

[ocdSCHACK]

Re: Another OCD build

Alright. My current crossover has some baffle step and plays really low. It can actually vibrate things in my apartment pretty well. I thought the speaker was loose or hitting something because of this sound I kept hearing. It turned out to be a picture frame on the other side of the room was making the noise! In a small room, someone could mistake there being a sub. Here's the annoying part. They are inefficient.
Can I add a resister in series anywhere to increase efficiency, or is this just asking for a house fire?

[ocdSCHACK]

Re: Another OCD build

As an update, I'd like to talk about the sound on these. It has been a textbook example of baffle-step. In my apartment, which doesn't have a single large open area, a simple crossover sounded great (it measured flat.) When I put them in my old man's wood shop, which is more/less a semi-large open room, they sounded awful. The tweeters would burn your ears off! In my small apartment, with the rear placed near a wall, they were great and efficient. I have redesigned the crossover to sound flat in a large room and would like any tips, comments, or suggestions on how to improve.
-How do you build a speaker for someone you don't know that has a lot of money? Clear treble? Deep bass?
-I have FRD's and ZMA's for anyone willing to help. So far for crossovers, I've build 2 opposite extremes and confused myself on what I should go for.
-What is the typical F3 on a "high quality" mass produced speaker?
-Crutchfield, which I hate as much as BestBuy, claimes 50-36,000Hz on the well rated speakers...but I know that's probably F20.

I need help.

I appreciate everyone's input!!!!!