Three way speaker with R45" ribbon

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Over the years I have picked up speaker parts with the intention of building a diy speaker. I have never done this so I am a neophyte but enjoy reading others foray into diy speakers. I would build a three way speaker if it makes sense. I would tri-amp and use electronic crossovers for the three way. I am soliciting your opinions if I am on the right track or if the design won't work or integrate well with the speakers I have. I want to use the drivers that I already own. The speaker would be about > 90db efficient.

1. Tweeter is a Newform 45" ribbon. I believe they cross this over at 1khz with a first order crossover in the speaker it came from. This is a sealed ribbon speaker.

2. Midrange would be two Audax HM130Z0 aerogel speakers. I picked up several of these a while ago because I heard a speaker with them (Leedh) and liked the sound. Midranges would be placed at ear height.
Questions:
a) Would the horizontal placement work centered to the ribbon?
b) Would sealed or open baffle work? Would it integrate with a sealed ribbon tweeter.
c) I would crossover at about 250Hz unless this is to low for that speaker (fs is 68hz).
d) How critical is the baffle width?
e) How critical is horizontal spacing to Newform ribbon?

3. The woofers would be a pair of Dayton RSS265HF-4.
Questions:
a) Spacing between mids and woofers?
b) Spacing between woofers?
c) Sealed vs ported?

I want to thank you for any input you may give. Of particular interest is how to integrate the ribbon to the midrange.

Best Regards,
gwho
 

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I have played with the exact arraignment you have drawn out there in a number of systems over the years in both open back AND sealed (all drivers).

Your physical arraignment in the drawing is spot on. Particularly having the mids to side of ribbon and centered.

About the only thing I would do different to what you mention is to use a lower crossover between woofers and mids. Probably down around 100 hz give or take a little.

IF the mids you have wont do the lower cross to woofers well I would strongly consider different mids. You dont need a high end mid as it wont be asked to do much above 1khz. Almost any decent small cone can do that. Its more important that the "mid" can go low enough to cross to woofers around 70-120 hz. This may mean using a driver thats not a true "mid" but rather a "bass mid" designed driver.

I would use sealed alignments for ALL as their transient response will likely match the big ribbon better than ported. Open back can be made to work too BUT in my experience I dont like the mix of sealed and open. Keep them the same always seemed best.I have done many system in both and in a mix.

Spacing between woofers and mid are not really an issue at 100 hz crossover

Spacing between woofers are not an issue

In the end the only issue with the long ribbon and point source mids is the way sound level drops off with distance. Its different for "lines" and "points". This means when you get everything Taylor to your liking in the listening seat then that position may be the only correct spot.
 
Lowmass,

I appreciate the information and assessment. I was worried that I was not going to get a response. I was hoping for someone that has tried a similar combination. I have a couple of questions if you don't mind. What issues have you found from a listening perspective having a point source with a line array? I assume all is good at or near the listening position if the levels are balanced. Perhaps a frequency imbalance at other listening positions? Did you like the sound of your combination and was having the line array ribbon a positive vs a point source tweeter?

There is a thread on diyaudio where several people discuss using the hm130Z0. A couple state that they were using it in a two way down to 70hz. I assume this is a ported speaker. Would a ported enclosure be an option if it got me down to 100hz? I believe the HM130Z0 in a sealed enclosure would have a 3db down around 150-175hz.

You state that mid to low frequency driver spacing is a non-issue. Similarly, placing the mid range (6") speakers horizontally adjacent to the ribbon is the best that can be done. My guess is that the spacing would be about 5" to the center of the ribbon. My question is the mid range to mid range spacing. What if I could add more mid range drivers. What kind of spacing could I get away (not placing them adjacent to one another) to make the mid range a line array (which would determine how many drivers I would need) or do the speaker frames have to be touching one another.

Finally, at what point does the horizontal woofer to ribbon spacing become an issue. Have you used a 7" - 10" woofer to get a sealed 100hz or would the spacing be too much.

Once again. Thank you for the help. It is much appreciated.

Regards,
gwho
 
Lowmass,

I appreciate the information and assessment. I was worried that I was not going to get a response. I was hoping for someone that has tried a similar combination. I have a couple of questions if you don't mind. What issues have you found from a listening perspective having a point source with a line array? I assume all is good at or near the listening position if the levels are balanced. Perhaps a frequency imbalance at other listening positions? Did you like the sound of your combination and was having the line array ribbon a positive vs a point source tweeter?

There is a thread on diyaudio where several people discuss using the hm130Z0. A couple state that they were using it in a two way down to 70hz. I assume this is a ported speaker. Would a ported enclosure be an option if it got me down to 100hz? I believe the HM130Z0 in a sealed enclosure would have a 3db down around 150-175hz.

You state that mid to low frequency driver spacing is a non-issue. Similarly, placing the mid range (6") speakers horizontally adjacent to the ribbon is the best that can be done. My guess is that the spacing would be about 5" to the center of the ribbon. My question is the mid range to mid range spacing. What if I could add more mid range drivers. What kind of spacing could I get away (not placing them adjacent to one another) to make the mid range a line array (which would determine how many drivers I would need) or do the speaker frames have to be touching one another.

Finally, at what point does the horizontal woofer to ribbon spacing become an issue. Have you used a 7" - 10" woofer to get a sealed 100hz or would the spacing be too much.

Once again. Thank you for the help. It is much appreciated.

Regards,
gwho

Point/line-
The way sound level drops off with distance is different between a point and a line. So if you adjust the loudness of each to be right at one distance it may be noticeably wrong at another distance. Thats not to say its a deal breaker. Look at Apogees models that use a long ribbon and a single cone just to the side of the ribbon. These were successful designs and I have done similar. It works BUT the room positioning and sweet spot are a bit small for my liking. Some are fine with that, some are not. I got great sound this way bat as said its a smaller listening window.

In general short ( less than about 60 inches)"lines" are a bit troublesome in vertical listening position due to beaming. They can be demanding in getting position in room just right but when they are it can be very good.

100 hz crossover vs 250 hz-

I cant say for sure how your mid would sound in a ported enclosure. In my experience the ribbons transient response demands a woofer that is well damped to match it. If porting that transient response may not be as good as a sealed and might not be as good a match.

The reason I suggest 100hz and not 250hz is that in my own experience I have always had an issue with woofers crossed at 250 hz. Always got best sound when crossed at eather 100 or 500-1khz. I could never get 250 hz to sound quite right.

I suspect this is because the magority of energy in live music is between about 100 and 500 hz, and tring to crossover right in the middle of that tends to cause problems. It may be that doing it electronically would be ok but I do not have enough experience here to say.


more mids-

I have used up to 10 inch woofer to side of ribbon with no problems.

If you can do more small mids as in a "line" of mids next to ribbon I would defiantly do it.Especially if have enough mids to make a "line" of them the same length as ribbon. This avoids the issue with point/line volume at distance issue, AND can be extremely dynamic.

best to keep the mids as close to each other as possible and as close to ribbon as possible. At 1khz cross over you should be fine.

If cross to woofer at 100 then the distance between mids and woofer are not a problem due to long wavelength at 100
 
Lowmass,

Once again, thank you for the advice. I wrote to hear from people who have done what I am about to do. I use a woofer that can go to 100hz sealed. I will also investigate adding more woofers to build an array the same length of the ribbon to see how that sounds.

I appreciate the help. You answered my questions spot on.

Regards,
gwho
 
Damic,

Thank you for the response. The ribbon does not go that low. I am restricted to 1k and above. The original speakers from which the ribbon came is a two way speaker (newform research r645) so this was always on the table if I wanted to replicate the original design.

Regards,
gwho
 
Lowmass,

One last question. Have you tried an array of inexpensive mid woofers. For example, the GRS 6PR-8 6-1/2" Poly Cone Rubber Surround Woofer ($8.50 parts express) or MCM 55-1240 - Cone Woofer, 8", Clear Polypropylene, Low Frequency ($13.99 Newark) would seem to work in a sealed enclosure and provide possible 100hz cut off. Any idea if this would be worse or better than a single or dual point source (higher quality woofer) since it would provide the same array radiation pattern as the ribbon. My concern would be that the an array of lower quality woofers may output lower quality sound (at this time I would not want to pay for 12 or 16 $150 mid woofers for this experiment).

Best Regards,
gwho
 
Lowmass,

One last question. Have you tried an array of inexpensive mid woofers. For example, the GRS 6PR-8 6-1/2" Poly Cone Rubber Surround Woofer ($8.50 parts express) or MCM 55-1240 - Cone Woofer, 8", Clear Polypropylene, Low Frequency ($13.99 Newark) would seem to work in a sealed enclosure and provide possible 100hz cut off. Any idea if this would be worse or better than a single or dual point source (higher quality woofer) since it would provide the same array radiation pattern as the ribbon. My concern would be that the an array of lower quality woofers may output lower quality sound (at this time I would not want to pay for 12 or 16 $150 mid woofers for this experiment).

Best Regards,
gwho
 
IMO this is a very good question.

Yes I have done it in "cheap" woofers BUT not the ones you mention. I used some really cheap 5, 6 inch and 8 inch plastic woofers I bought from radio shack during some closeout sale many years ago.

They all had simple motors, basic foam surrounds, and poly cones. Nothing at all exotic.

They worked surprisingly well. All of them.

They were all well behaved up to about 3-4 khz and I was crossining between 400 and 1 khz. The sheer number of the drivers meant that they did not have to move much at all and therefore a good motor and suspension simply was not needed.


So yes if it were me and I was going to do a "line" of cones, and my cross was 1K or lower, I would find a decent 6-8 inch "cheap" cone with a smooth response out past 2-3 khz AND that gives the desiered lower freq perf in the size box I want.

When theres a bunch of small cones that hardly move at all and are not taken to the upper midrange , theres a big advantage. You can go cheap and still get ALL the perf of the really expensive cones. In fact IMO its often better. The cheap cones are often very light small motor etc, when in the right setup and not being asked to do anything up high in mids or to make big peak to peak swings in bass, they seem to have an advantage over even the exotic cones. Especially in mid bass dynamics.
 
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Lowmass,

One last question. Have you tried an array of inexpensive mid woofers. For example, the GRS 6PR-8 6-1/2" Poly Cone Rubber Surround Woofer ($8.50 parts express) or MCM 55-1240 - Cone Woofer, 8", Clear Polypropylene, Low Frequency ($13.99 Newark) would seem to work in a sealed enclosure and provide possible 100hz cut off. Any idea if this would be worse or better than a single or dual point source (higher quality woofer) since it would provide the same array radiation pattern as the ribbon. My concern would be that the an array of lower quality woofers may output lower quality sound (at this time I would not want to pay for 12 or 16 $150 mid woofers for this experiment).

Best Regards,
gwho
 
I had newform 645s for a few years. Here is some of what I learned about them through several years of experimenting. The best way to go is to bi amp with a low level cross over IME. The stock 645 had 2.7 ohms of resistance in series with the 2 paralleled SS 8545 drivers to match the sensitivity to the ribbon. Not a real good use of a high quality driver IMO. Big improvements were had using low level cross overs and bi amping. The ribbon driver itself weighs something like 45 lbs and is basically a long steel tube open on one side. If you fasten it directly to the top of the box it tends to ring IIRC at about 220hz. Some isolation is definitely needed.
Although rated to go down to 1khz I had better luck with higher crossover points. I always heard a coloration at lower crossover points. I think a first order crossover is too shallow for high output levels when set at 1khz. I used a Marchand Electronics 4th order LR crossover which seemed to work better, but I never really got the sound I wanted in my mid sized rectangular room. Eventually I sold them and moved on.
 
Lowmass,

Once again, thank you for the input. I am glad you saw merit to a line array of lower cost midwoofers. In reading about line arrays it seems there are many that do not like them, especially in a short array. I also did not want to buy 16 $150 > woofers just to try it out. So your input was invaluable to me.

I know this is a kluge but I tried the ribbon with a couple of speakers just to see how they sounded. I used an Ashly analog crossover (24db/octave) to cross the ribbon to two different speakers. I first crossed the ribbon to an old Snell Type C speaker at 1K. I believe the Snell uses Vifa drivers (4" and 10").

The other speaker is more of a HT speaker. It is a Mirage OS3-Fs. I don't believe it is a line array but it has two 4.5" midwoofers and (5)-4.5" passive speakers to generate low frequency. The Mirage also has an omni tweeter/midrange that distributes sound in all directions under the top cap. I listened to the mirage with the cap covered by cloth and open (as there was output from this speaker when crossed at 1K.

I tried to match the gain of the speakers with a radio shack meter. They did sound different from one another. The Snell combination obviously had a lot more bass. Interestingly, I liked the Ribbon/Omni combination better which is why I asked the question about an array of sealed budget midwoofers.

Best Regards,
gwho
 

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Bfpca,

Thank you for sharing your experience with the 645 Ribbon. I will definitely biamp or triamp with the final version of this speaker. You are correct that the ribbon is very heavy. I will play around with the crossover frequency per your suggestion. Also, you mentioned isolation of the ribbon to the box. How would you do this? Would you put some type of isolation material between the box and the ribbon mount?

Regards,
gwho
 
I ended up building better braced boxes than the stock ones. The bracket is usually mounted to the inside of the box with silicone caulking to give some vibration isolation but given the heavy weight of the ribbon it still needs to be fixed securely. I put sorbothane under the ribbon and also between the ribbon and the mounting bracket. I also isolated the mounting bolt from the bracket with a rubber washer and I machined off the threads where the bolt would have contacted the bracket. So the bolt did not have any direct contact to the bracket/box.
 
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