My next project

[NickH]

Hi Martin,

Ya I know. Its just a temporary. Ive got almost all the parts I need to build them. Just waiting on 4 more inductors. I dont have a measurement mic but Im thinking about ordering 1 next week.

How could you use the impedance curve to calculate the component values for a crossover? The impedance is never constant. Not saying it cant be done. Im just saying I dont know how to do it. But I know there will be a lot of trial and error. Doubt Ill get it right the first time I put it together.

Thanks,
Nick

Hey Nick!

Good job! They are looking very nice!

When it comes to the impedance curve of a speaker, it is changing a lot over the frequencies, and those "universal" filters will most likely not give a good result. It will help you if you have a measure microphone, to see how fare the theory is from the real world, when you are trying different values in the crossover
Remember, it is not the DC, or "Z" impedance of the driver, but the impedance curve that often appears along with the response curve, you have to use when making crossovers.

Best regards
Martin

[Ear4life]

Hi Nick

Start with picking a crossover frequency. Then look at the impedance curve, and see what it shows at that specific frequency. It might be 6 or 10 ohm or something else. And that value should be used along with crossover frequency to calculate the components (this is how it works in theory) But it takes a mic to make the best result, it can also be a very good leaning experiences.

Best regards
Martin

[NickH]

I feel stupid now. I should have thought of that. But anyway, I'll be increasing the crossover frequency in the future so I will use that method. I need to get something to measure it though.


I had the tester parts express sells but it died. I need to buy some testing toys. A measurement mic too.

Nick

Hi Nick

Start with picking a crossover frequency. Then look at the impedance curve, and see what it shows at that specific frequency. It might be 6 or 10 ohm or something else. And that value should be used along with crossover frequency to calculate the components (this is how it works in theory) But it takes a mic to make the best result, it can also be a very good leaning experiences.

Best regards
Martin

[NickH]

Had an eventful weekend. I spent some time with the jensen tweeters connected to the speakers. I was very pleased with the sound. They only go up to 15k, and Im sure it starts to roll off way before that. But they just are so easy to listen too. Then I thought to switch the ribbons back in. Man what a big change. I was hearing a shimmer on cymbals that I just wasn't hearing before. Im in a tough spot as they both and very nice qualities.

But I have decided that I need to try some jbl tweeters on them. Im thining either 2404's or 2405's. I want to keep they 3 way otherwise I would just use both the jensen and fountek tweeters. But as with ribbons, there lasers.

I also for kicks hooked them to a little class d amp. It pushes max 5 watts at 8 ohms. Im quite surprised. But its was a duh moment. All my audio friend where telling me that you dont need much over 10 watts with them. I knew they were efficient, but I just needed to show my self how efficient they really are.

Ive got a dynakit st35 that will be running them for a bit. I just have to figure out a little issue with it. The power tubes are not seeing any bias voltage. But once it's up and running they should be pretty good driving them until I finish the next amp im working on. Its a triode mode class a push pull kt120 amp. It will probably only produce about 10 watts. Maybe a little more if im lucky. But it should work pretty well at driving them until I build a single ended gm 70 amp.

I did get my thorens td 124 working and hooked it up to them. A buddy of mine came over. He love's the song inagaddadavida so I put on the record. I had my emotive amp hooked to them at the time. It produces 125 watts rms. I crank the you know what out of it at the drum solo. It was soooo freaking loud. MY GOSH. I know I lost some hearing on that one. I've been to concerts that were more quite. But I torned it down pretty quick. The jensens were on top and I doubt that can handle more then a watt or 2. The speakers they were on were only rated at 30 watts total.


But for an impromptu setup it sounds really good. Everyone who hears is say wow. But no audiophiles have heard it. Im sure it would be picked apart. Once the crossovers are built it will improve quite a bit.


Nick

[sbjacob]

Had an eventful weekend. I spent some time with the jensen tweeters connected to the speakers. I was very pleased with the sound. They only go up to 15k, and Im sure it starts to roll off way before that. But they just are so easy to listen too. Then I thought to switch the ribbons back in. Man what a big change. I was hearing a shimmer on cymbals that I just wasn't hearing before. Im in a tough spot as they both and very nice qualities.

But I have decided that I need to try some jbl tweeters on them. Im thining either 2404's or 2405's. I want to keep they 3 way otherwise I would just use both the jensen and fountek tweeters. But as with ribbons, there lasers.

I also for kicks hooked them to a little class d amp. It pushes max 5 watts at 8 ohms. Im quite surprised. But its was a duh moment. All my audio friend where telling me that you dont need much over 10 watts with them. I knew they were efficient, but I just needed to show my self how efficient they really are.

Ive got a dynakit st35 that will be running them for a bit. I just have to figure out a little issue with it. The power tubes are not seeing any bias voltage. But once it's up and running they should be pretty good driving them until I finish the next amp im working on. Its a triode mode class a push pull kt120 amp. It will probably only produce about 10 watts. Maybe a little more if im lucky. But it should work pretty well at driving them until I build a single ended gm 70 amp.

I did get my thorens td 124 working and hooked it up to them. A buddy of mine came over. He love's the song inagaddadavida so I put on the record. I had my emotive amp hooked to them at the time. It produces 125 watts rms. I crank the you know what out of it at the drum solo. It was soooo freaking loud. MY GOSH. I know I lost some hearing on that one. I've been to concerts that were more quite. But I torned it down pretty quick. The jensens were on top and I doubt that can handle more then a watt or 2. The speakers they were on were only rated at 30 watts total.


But for an impromptu setup it sounds really good. Everyone who hears is say wow. But no audiophiles have heard it. Im sure it would be picked apart. Once the crossovers are built it will improve quite a bit.


Nick

Nice work I have the JBL2404 baby cheek tweeters on my A7's a very nice match I also added a BBE sonic maximizer to my A7 setup and it really helps more on the LF .

[intercity125]

Hi Nick,

The speakers have really come along nicely, and it sounds like you are well on your way to finding the correct crossover points to suit your tastes. I wanted to ask about the modified reflex port and how it has affected the bass response. Not sure if you had heard the speakers before the mod, but I am curious to know if the bass response had a noticable improvement after the mod? I've also seen where some have closed in the cabinet completely and not used a port, at all. I'd sure appreciate your thoughts on the matter whenever you get the time. Thanks!

Willy

[NickH]

Hey Willy,

Yep went thru the process of charting the 416's impedance versus frequency. It changes quite a bit. I put a zobel network on it in the end. After all that work I have decided its just easier to go active. Im in the process of building a 3 way tube active crossover with a summed output below 100 hz for the subwoofer.. But I am thinking about still using a passive crossover for the mids to tweeters still. I havent made my mind up completely. I did on the other hand fix one problem with the st35 amp Im going to use on them. But I created another problem. I need to rewire the grounds on the amp. There are too many and its created a ground loop. So lots of hum.

Oh in regardes to the changes reflex tuning. Its not bad but not perfect. No matter what you do, they will always have a 6 db drop below 100hz. Thats why Im going the subwoofer route.
But progress is being made.

Nick

Hi Nick,

The speakers have really come along nicely, and it sounds like you are well on your way to finding the correct crossover points to suit your tastes. I wanted to ask about the modified reflex port and how it has affected the bass response. Not sure if you had heard the speakers before the mod, but I am curious to know if the bass response had a noticable improvement after the mod? I've also seen where some have closed in the cabinet completely and not used a port, at all. I'd sure appreciate your thoughts on the matter whenever you get the time. Thanks!

Willy

[intercity125]

Hey Nick,

Thanks for the info. Active is a great way to go, as there is so much flexibility and choice when it comes to slopes and cut-offs; the combinations are virtually endless.

The reason I asked about your port mod is because I have a chance to purchase a pair of A-7 cabinets, verses making a pair of Onken enclosures myself. I wasn't looking forward to the build, but I do like the design. The A-7's, on the other hand, will need a bit of TLC and I would, most likely, do a port mod on them, as well, but that's the fun of it.

I just have to decide which way to go.

Willy

[Ear4life]

Hello guys!

Nick: To make a very good passive crossover isn´t easy. So going with active crossover gives other opportunities and advantages as well. And it is easy to try out new components Keep it up!!

Willy: It is a must to create a real bass reflex rather than just one big hole especially if used at home (just where we want it!!) , it will extend the response in the low end as if it was different speaker. The Altec A7 / 828 cabinet does sounds very good, and has good internal volume. Most of the music-people I know prefer the A7/828 over the Onken for different reasons. What I really like about the 828 is that you can match the time domain of the bass driver and the compression driver on top very well.

Best regards
Martin

[intercity125]

Hi Martin,

I will, most likely, opt for the 828 cabinets simply because they are complete and need the least amount of work to get them done. I will still go through them with a fine-tooth comb, as my better half expects nothing less if they are going to be used in the house!

I've heard 828's (A-7 500's) on a couple of occasions and agree with your comment that they sound very good. I've just never heard a pair that someone has tweaked, if you will. Regarding the Onken, I have neither seen nor heard a pair, I just like the design aspect of them. I will be looking at the 828 cabinets, hopefully, this weekend, so I will report back and let you know how it went. Cheers!

Willy

[NickH]

Hello Gentlemen,

Didn't get much done this weekend. Have to get my garage organized. I started playing around with trying to diy some smith horns. But I think I'm going to hold off. I've got 3 2 by 4 foot sheets of 3/4 inch bb ply. I think I'm going to go full altec. Yep I'm going to put on some wings. I still want to try to diy some smiths but right now I'm still really digging these 2380 copies.

As for the wings I'm not going to go crazy. I figure a foot on the top and sides should do it. Plus my wife really wants the horns mounted in a baffle. The wings are supposed to really help the bass response.

I'm also thinking about putting a sub together. I've got a 7cuft cabinet that I built a while ago. I'm going to get 2 parts express 15" woofer and throw'em in there. I've got a 300 watt 2 channel amp to drive them for now. I'm going to run them from 2 100hz summed low pass active filters. Not going to run any equalization at first. Just run them straight.

Hey Willy. Okens are very nice. But the 416 is not the best driver for them. It will work though. The ultimate in onken driver is the 515. A very good friend runs onkens with iconic 515's in them. Though iconic calls them by another name. They are not the easiest to implement. The impedance of everything has to be taken into consideration. But your patience will be rewarded with stellar performance. But I would say that these 828's come in a pretty close second. But the onkens do a tad better in the bass department. But not much below 35 to 40 Hz. A sub still helps.

As for my crossovers they will still be analog. Plus I'm still going to use Passive crossovers between the mids and tweeters. I just wanted to have a separate amp for the woofers.

the crossovers are tube. Bass is fourth order sallen key and the woofer to mid tweet is 3 second orders in series.

For now I'm not going to bother with time alignment.

More later. Now I've got some John Williams to listen to.

Nick

[fpitas]

On the subject of damping the 511, here's my $0.02:

http://www.diyaudio.com/forums/multi...ml#post3060342

A skeptical friend repeated my procedure with similar results; no ringing, and to his surprise a much better sounding horn. This despite his horn being solidly mounted to a baffle board, with a good gasket.

Besides damping the ringing, I think the horn also needed to be reinforced against vibration in many spots, especially the bells.

BTW, later I discovered that "cocooning" the rear of the horn using the polyurethane adhesive, behind the flange back to the neck, made a small difference. Once again I think sound was radiating from the horn from vibration. The experience has made me appreciate why TAD, for example, starting making their horns out of solid or laminated wood, with thick wall sections everywhere.

[NickH]

Hi Fpitas,

Thatnks for the info. We arent actually talking about the 511 horn flares. I was trying to dampen the horn flares on the 828 bass horn. But this might be usalble here too. Ill check it out. Thanks.

Nick

On the subject of damping the 511, here's my $0.02:

http://www.diyaudio.com/forums/multi...ml#post3060342

A skeptical friend repeated my procedure with similar results; no ringing, and to his surprise a much better sounding horn. This despite his horn being solidly mounted to a baffle board, with a good gasket.

Besides damping the ringing, I think the horn also needed to be reinforced against vibration in many spots, especially the bells.

BTW, later I discovered that "cocooning" the rear of the horn using the polyurethane adhesive, behind the flange back to the neck, made a small difference. Once again I think sound was radiating from the horn from vibration. The experience has made me appreciate why TAD, for example, starting making their horns out of solid or laminated wood, with thick wall sections everywhere.

[fpitas]

Oops My reading comprehension fail.

Hi Fpitas,

Thatnks for the info. We arent actually talking about the 511 horn flares. I was trying to dampen the horn flares on the 828 bass horn. But this might be usalble here too. Ill check it out. Thanks.

Nick

[NickH]

No problem.

Oops My reading comprehension fail.