Altec

[adityapm]

Thanks for such a detailed write up Aditya. Wealth of info there. Let me wrap my head around it slowly.

With regards to RCA MI 9584, Victor of Japan branded equivalent is what I have. It's bloody fantastic. Never a harsh note and its like honey. Very easy on the ears. But as pointed out it must be used with a tweeter up top as it goes upto 8000hz (movie soundtracks at the time only went that high up). Most small jazz trio music, vocal focused music and the like, sounds great 2 way. The phenolic diaphragms used are very rounded and just beautiful sounding. I would like to retain them for that.

My 288c have an aftermarket titanium diaphragm which is very detailed can sound a tad sharp and fatiguing at higher volumes only. I must change it to an aluminium diaphragm soon. But my observation within this brief period of using them is that the 288c even with the titanium diaphragm are very exciting and have a large sound. Very enjoyable. The scale of them and the large sound the 288s throw is very nice.

GPA wrote and said 288 diaphragms will be available on their website in January but it hasn't happened. They have the smaller format diaphragms listed on their website.
Now coming to the cabinet. It is narrowed down to an 815 and a concept A9 in my use case.
I am leaning more towards the A9 but would like to reduce the height to 4ft like you have mentioned can be done. But so will other allied measurements i am guessing.
I have a 2ft x1 ft concrete beam hanging down from the ceiling just about 3 to 4 ft away from where my speakers are placed. You think suspect qts and out of spec issues with my drivers will be better overlooked by a sealed A9 cabinet? Plus it helps that they are easier to build.
Another question that comes to my mind is should I worry about internal bracing or partitions etc or just build a bigger box as per the A9 concept spec?

The RCA MI95854 will sound balanced as long as the lower 3db tunning of the (bass) enclosure stays above 62 Hz. One will not miss anything. For a 12KHz top-end, the bottom end has to be at 40 Hz to make the sound sound normal/balanced. For a 15KHz top-end the bottom has to be at 33 Hz. Unless this is maintained, it will sound either thin-ish (bass lacking) or dull (HF lacking). Phenolic diaphragms are very good in the lower-mid area. After all they are closer to paper. Aluminum is closer to phenolics than titanium, and titanium is closer to aluminum. Cascading the drivers in this way gives the best transition from one stage to the other. As long as the music does not have anything below 70/80 Hz the RCA MI95854 will sound ok. Say The Beatles, they don't have anything below 100 Hz. Their recordings while mastering used to pass through a Hi-Pass filter wiping everything below 100Hz.

About GPA, nothing is working. Nobody is there now. They are replying like this to everybody as if to keep things afloat. Nearly 250 diaphragm orders (US local) are waiting since past 11 months.

The box construction has to be very rigid with lots of bracing of course. But these are a lot simpler than building a horn enclosure. Once finalized, I will give you the plans to do it. It will be quite heavy.

The parameter deviations will not be an issue here, as it will be a larger than required size, and we will fill it up by manipulating the parameters. Of course we will lose cone excursion for full wattage drive. But that will be a welcome feature also, meaning the system will also become more sensitive. I am using such an enclosure since 2016 November. It is like a big studio monitor sound. I never use tone controls. What ever the studio (where the programme was scored) has done, I listen to that. I have never needed tone controls. The studios use much costlier equipment.

The concrete beam issue may or may not affect. We will see to it later.

Bye

 

[Sushant Sharma]

The RCA MI95854 will sound balanced as long as the lower 3db tunning of the (bass) enclosure stays above 62 Hz. One will not miss anything. For a 12KHz top-end, the bottom end has to be at 40 Hz to make the sound sound normal/balanced. For a 15KHz top-end the bottom has to be at 33 Hz. Unless this is maintained, it will sound either thin-ish (bass lacking) or dull (HF lacking). Phenolic diaphragms are very good in the lower-mid area. After all they are closer to paper. Aluminum is closer to phenolics than titanium, and titanium is closer to aluminum. Cascading the drivers in this way gives the best transition from one stage to the other. As long as the music does not have anything below 70/80 Hz the RCA MI95854 will sound ok. Say The Beatles, they don't have anything below 100 Hz. Their recordings while mastering used to pass through a Hi-Pass filter wiping everything below 100Hz.

About GPA, nothing is working. Nobody is there now. They are replying like this to everybody as if to keep things afloat. Nearly 250 diaphragm orders (US local) are waiting since past 11 months.

The box construction has to be very rigid with lots of bracing of course. But these are a lot simpler than building a horn enclosure. Once finalized, I will give you the plans to do it. It will be quite heavy.

The parameter deviations will not be an issue here, as it will be a larger than required size, and we will fill it up by manipulating the parameters. Of course we will lose cone excursion for full wattage drive. But that will be a welcome feature also, meaning the system will also become more sensitive. I am using such an enclosure since 2016 November. It is like a big studio monitor sound. I never use tone controls. What ever the studio (where the programme was scored) has done, I listen to that. I have never needed tone controls. The studios use much costlier equipment.

The concrete beam issue may or may not affect. We will see to it later.

Bye

I didn't know the bottom and top end were interconnected like that. It only makes sense that they are. You learn something néw everyday.

My current cabs for the altecs were made for an 8 inch full ranger so I am expecting huge gains moving to a dedicated and proper speaker cabinet. Looking forward. Thank you.

 

[adityapm]

I didn't know the bottom and top end were interconnected like that. It only makes sense that they are. You learn something néw everyday.

My current cabs for the altecs were made for an 8 inch full ranger so I am expecting huge gains moving to a dedicated and proper speaker cabinet. Looking forward. Thank you.

You mean they are now with the 416-8cs ?, enlarging the holes to accommodate them ?
Send me the box size.

Thanks

 

[Sushant Sharma]

You mean they are now with the 416-8cs ?, enlarging the holes to accommodate them ?
Send me the box size.

Thanks

Post in thread 'Lii (song) audio silver 8.' https://www.hifivision.com/threads/lii-song-audio-silver-8.92298/post-1030359

These cabinets. Approximately 18 inches wide and 34 inches tall and 22 inches deep. Yes, I enlarged the hole to accommodate the 416 8c. I knew I was going to receive the 8a in the future and didn't commit to a new cabinet.
The 416 8a I just received this week and haven't yet heard inside a cabinet.

 

[adityapm]

Post in thread 'Lii (song) audio silver 8.' https://www.hifivision.com/threads/lii-song-audio-silver-8.92298/post-1030359

These cabinets. Approximately 18 inches wide and 34 inches tall and 22 inches deep. Yes, I enlarged the hole to accommodate the 416 8c. I knew I was going to receive the 8a in the future and didn't commit to a new cabinet.
The 416 8a I just received this week and haven't yet heard inside a cabinet.

This box (around 9 cu.ft) is perfect for a 416 as a standard BR design. But what about the Silver-8 project for which you had got these boxes built just a year back ? I think you should just use the 416-8c pair for some time now as it is, and also play with the other Altec/RCA units for some time in diff. prmutations & combinations and get the picture in the head first. This will result in a good decision/design choice. Let me know what you decide/want to do.

 

[analogadikt]

Yes, just a typo. These phenolic drivers are in the circuit only for the nostalgia sake.

The same also for old alnico drivers. I prefer the ferrites. They are a bit harsh when driven hard, but never lack punch or bite. After all they are rocks. But alnicos are metal. They are very permeable, and the hysteresis curve changes as the current varies. This is the reason why the measured parameters when used do not give the desired results. Parameter measurements are normaly done with very little signal strength, as little as 1 milliwatt. But real use happens always at higher currents.and at that level the parameters have changed. Thats what happens.The trick here is to use a higher current for the TSP measurements, and then it will work when they are plugged in. But driven hard they will not give that bite that one expects. They will somehow prevent clipping, and sound roundish. It is like triodes and pentodes. When driven hard triodes will still keep it smooth but wiill lose the bite, whereas pentodes will show their true nature, a pure current source, and will go on driving hard with bite and punch. Ferrite drivers' TSPs always work alright.
After all we have graduated from alnicos to ferrites, from phenolic to metallic. Once the production techniques were at hand, all became metal diaphragms and higher bandwidths arrived.

Thanks

Ha Ha Ha
That is going to make some guys here a bit unhappy.

Regards,

 

[srinisundar]

Ha Ha Ha
That is going to make some guys here a bit unhappy.

Regards,

Nothing going to make unhappy. Just for arguments they can,

Music is always a listeners choice and all the measurements is nothing once you liked the sound output. All the human ears are tuned for different hearing but the speakers are tuned perfectly with fixed crossover.

So we have to tune only the ears not the speakers which have fixed values. So stay tuned and take full measurement of your ears first.

Have fun guys. All the forum is for healthy discussions without biting too much about the ears.

 

[keith_correa]

So we have to tune only the ears not the speakers which have fixed values. So stay tuned and take full measurement of your ears first.

What organs does one need to press/poke for the tuning of one's ears?

 

[srinisundar]

What organs does one need to press/poke for the tuning of one's ears?

Listener's choice, what they think they have heard properly and know those frequencies and sounding best or natural or neutral or ??

 

[Hari Iyer]

And I thought room was important

 

[grindstone]

Hey @Sushant Sharma do these dimensions look close to your 8-cell?

Just wondering what the horn angles are

 

[Sushant Sharma]

Hey @Sushant Sharma do these dimensions look close to your 8-cell? View attachment 84149

Just wondering what the horn angles are

The RCA MI 6438 in the photo has bigger dimensions. My 2x4 cell horn is smaller at 27W X 28LX 15H (inches). Length is inclusive of throat. I will have to figure how to measure horn angles.

 

[grindstone]

Thanks--no need to measure anything on my account. The dimensions you gave are perfect and I appreciate you taking the time to get numbers and post!

 

[Sushant Sharma]

Nothing special just an update..Couple of days back I opened the rear rounded metal cover of the 288c and played it open back. I thought it sounded nice. There is no felt pad on the inside of the driver rear covers. I think i might cut one to size and glue it on. I cleaned some rust deposit on the face of one of the drivers and cleaned the voice coil gap with paper. After touching a screw driver i found one magnet to have a tad bit stronger pull than the other.

The aluminium diaphragms for the 288s have reached Delhi customs from Japan. Looking forward to swapping out the current titanium ones I am using. I am awaiting the carpenter i know, to come back to town so a new cabinet build can get underway.

 

[grindstone]

It's funny your post just beat my reply but I'm leaving it all anyway
---------
Manohar's "instigating thread" has me thinking of this all again. Lots of good advice in this thread. I think that, if you have corners available to use, you might do just fine with either of the over-and-under short horn types (sort of aperiodic 820/821 or dual/separate reflex lansing C31 (d31050 etc)) type cabinets if you want them. They're not much longer than the 817 horns, it's just a different thing if corners work and/or if that works better in your room and arguably easier to "package" as furniture if that mattters. I have plans for those things if you care. Either way, you'd need to modify them to enclose the extra "way" in the 3-way, etc.

You know, Hilliard's house rig was big IB like others are talking, too. That'd be a sort of nearly foolproof approach--IF you like the sound.

I simmed a 416 in the Lii cab and compared it to the Silver 8 response and, if you like it the way it is, well...to Srini's point--that's important--it wont be the same in a big infinite baffle system (unless it gets tall/skinny/pipe-ey). I looked at a few different size pipes to see if something in the Lii-like approach made sense for testing a 1-driver system compared to what you already have. It really doesn't -- not until/unless it gets pretty big. If you just want a temporary thing that gets the multicell up in the air at ear-height on a pipe, it's not much bigger (50L) than the Lii cabs.

The other thing is wondering about how you want everything to work in your room--ie as lowboy or high and whether you can use the corner / move that bookshelf etc.

I've lived with one in-corner and one out-of-corner speaker for years and the honest answer, if a person is completely finicky, is that they both need different EQ to be "right" and they're never quite the same. Boundaries matter, so...with all large systems, how you use your room matters and I really don't know your thinking on that.

I could understand if you just started making giant midhorns for the RCA or something else and focused on that and adding pieces around it. That sort of depends on what you want to put on top and how to blend the horn patterns at the crossover points. Lots of ways to think about this (and every one of them is FUN!)



Oh--if you need 288 diaphragms, just skip GPA and get Radians if your 288's are compatible types.

 

[Sushant Sharma]

It's funny your post just beat my reply but I'm leaving it all anyway
---------
Manohar's "instigating thread" has me thinking of this all again. Lots of good advice in this thread. I think that, if you have corners available to use, you might do just fine with either of the over-and-under short horn types (sort of aperiodic 820/821 or dual/separate reflex lansing C31 (d31050 etc)) type cabinets if you want them. They're not much longer than the 817 horns, it's just a different thing if corners work and/or if that works better in your room and arguably easier to "package" as furniture if that mattters. I have plans for those things if you care. Either way, you'd need to modify them to enclose the extra "way" in the 3-way, etc.

You know, Hilliard's house rig was big IB like others are talking, too. That'd be a sort of nearly foolproof approach--IF you like the sound.

I simmed a 416 in the Lii cab and compared it to the Silver 8 response and, if you like it the way it is, well...to Srini's point--that's important--it wont be the same in a big infinite baffle system (unless it gets tall/skinny/pipe-ey). I looked at a few different size pipes to see if something in the Lii-like approach made sense for testing a 1-driver system compared to what you already have. It really doesn't -- not until/unless it gets pretty big. If you just want a temporary thing that gets the multicell up in the air at ear-height on a pipe, it's not much bigger (50L) than the Lii cabs.

The other thing is wondering about how you want everything to work in your room--ie as lowboy or high and whether you can use the corner / move that bookshelf etc.

I've lived with one in-corner and one out-of-corner speaker for years and the honest answer, if a person is completely finicky, is that they both need different EQ to be "right" and they're never quite the same. Boundaries matter, so...with all large systems, how you use your room matters and I really don't know your thinking on that.

I could understand if you just started making giant midhorns for the RCA or something else and focused on that and adding pieces around it. That sort of depends on what you want to put on top and how to blend the horn patterns at the crossover points. Lots of ways to think about this (and every one of them is FUN!)



Oh--if you need 288 diaphragms, just skip GPA and get Radians if your 288's are compatible types.

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View attachment 84460

Thanks for taking the time out to post a detailed reply. Very helpful. Appreciate your inputs @grindstone.

1. I am now leaning towards using both the RCA upto 7k or so and using the 288 above that. Partly because I don't want to part with any of these drivers but also only if it makes any sense to do so.

I have used the Beyma compression drivers in conjunction with both the above drivers simply with a .33 and 1 mfd cap. And I like what the beyma does up top especially with RCA given they dont go up very high and the beymas go upto 20000 hz on paper. I feel the 288 might do it better. Must try to mount them together today and see. The 288s are very heavy and I need to be careful mounting them with my current make shift mounting set up being not very sturdy. Do you think this to be a good direction to take?

Also when I run just the 288c I feel like I don't need a tweeter uptop but I am aware that the convention seems to be to use a bullet/super tweeter of some kind.

My fountek ribbon tweeters don't do any better than 2 compression drivers put together I feel, so I have given them a rest.

2. 3 or 4 way also means a complicated crossover but with some help I think it can be achieved. Would I need a specialised crossover or can I still use the 288s up top with just a capacitor in the path?

3. This combination will physically be taller if I were to put horns on both compression drivers. The 2 pairs of bass drivers can be put in a 817 like bass enclosure which is very similar to the one you have posted.

4. My room also opens up on one side after 6 ft or so and there's a wall on the other side through and through. With the help of adjustment in volume attenuation on my 6v6 amp, I get a centered image and keeping both volume pots at same levels makes the image lean towards one side.
I have a door on one side and a shelf fastened to the wall on the other side so corner placement might be difficult for me but I do see how this could easily be made to look like part of the furniture if the cabinet is done well.

5. The Lii audio cabinet I built was reduced in height when I put the 416c in that cabinet. At the moment there's more mid range and I feel the bass woofers aren't being made to work out. I have noticed the stand up bass to take precedence along with the high frequencies. I am hoping the curved wings in front of the 817 like cabinets will help the lower frequencies become better.

"I could understand if you just started making giant midhorns for the RCA or something else and focused on that and adding pieces around it. That sort of depends on what you want to put on top and how to blend the horn patterns at the crossover points."

Basically what you have said here is what I need to figure out.