Altec

[Sushant Sharma]

Partly by design and partly fortuitous but I have come in possession of a pair of Altec 416 8cs and now i will receive a pair of 416 8a (heathkit As 101 branded altecs) woofers this coming week. Both with original paper cones. The 8c are 16 inch and the 8a are 15 inch.

I bought a pair of RCA MI 9584 compression drivers and then a pair of Altec 288c came my way and I bought that too. I need to get better diaphragms for the altecs but have the original diaphragms for the RCA. And also a pair of 8 cell horns that are heavy and inert with stuffing inside. These could be RCA or Vitavox i am not sure will do the horn duty and I prefer these to the Lecleach wood horn in my system.

All these events have happened over a time frame of almost a year or slightly less.

Now, I am thinking of using both the altec woofer pairs together in an Altec 817 cabinet.

Though the 817 cabinet plans are available on the internet but I need to think about crossover design for them. I am currently using a simple 1st order butterworth crossover on a single pair of altec 416 8c..

Please share any comment and advise you might have on how I should go forward especially with crossover. Am I on the right track or am I biting off more than I can chew since my knowledge of crossover designs is very limited? My room is roughly 24 ft X 20 ft and I see this Double woofer combination being used in similar sized rooms. Sharing some photos.

 

[yogibear]

Is it just your room size (a dream for many including myself) or you are in a possession of a magnet that attracts legends from RCA or Altecs ?

 

[Yelamanchili manohar]

Partly by design and partly fortuitous but I have come in possession of a pair of Altec 416 8cs and now i will receive a pair of 416 8a (heathkit As 101 branded altecs) woofers this coming week. Both with original paper cones. The 8c are 16 inch and the 8a are 15 inch.

I bought a pair of RCA MI 9584 compression drivers and then a pair of Altec 288c came my way and I bought that too. I need to get better diaphragms for the altecs but have the original diaphragms for the RCA. And also a pair of 8 cell horns that are heavy and inert with stuffing inside. These could be RCA or Vitavox i am not sure will do the horn duty and I prefer these to the Lecleach wood horn in my system.

All these events have happened over a time frame of almost a year or slightly less.

Now, I am thinking of using both the altec woofer pairs together in an Altec 817 cabinet.

Though the 817 cabinet plans are available on the internet but I need to think about crossover design for them. I am currently using a simple 1st order butterworth crossover on a single pair of altec 416 8c..

Please share any comment and advise you might have on how I should go forward especially with crossover. Am I on the right track or am I biting off more than I can chew since my knowledge of crossover designs is very limited? My room is roughly 24 ft X 20 ft and I see this Double woofer combination being used in similar sized rooms. Sharing some photos.

Hi Sushant...that will be one awesome build for sure ...hearty congratulations on your acquisitions...Iam sure there is a story well worth a fun read on how they all landed in remote Himachal for a start .

Now coming to the crossover design, are you open to digital crossovers and running the altecs active with multiple amps or do you want to go with a passive crossover. This will decide the future course of action.

If you want to go passive, and only need to decide which crossover frequencies and slopes you need before committing to the build, then using something like a minidsp to try different crossover points will be ideal to finalize and then get passive crossovers built.

More once you tell us, if you will be staying passive or active

 

[Sushant Sharma]

@yogibear haha..it took some searching and looking high and low but finally I got lucky. Thanks.
@Yelamanchili manohar
thanks Manohar. Yes, these arrived from Hyderabad, Banglaore, Chennai and Vietnam. DTDC, train station pick up, flights and some volvo bus drivers also got to know me in the process. From friends who did not take my calls after hearing about size of packages to other not so close friends who lugged 17 kgs on international flights for me. This hobby I tell ya...
Many thanks for the active vs passive suggestion..very recently a few videos on youtube have appeared on whether to go active or passive. I feel active might be for me in the future because of the know how involved. Passive might be easier to build. Been looking for a tried and tested crossover design which might be easier to build and implement. I do not know how to use dsp and mics etc though u know I must learn that if I want to do justice to these components. How would you have proceeded if you were in my place?

 

[panditji]

Sushant, I don't know what your plans or intentions are but the ecosystem of Himachal is already quite fragile.. I remember floods last year and with a pair of a 16 and 15 inch driver in a speaker, it seems you are planning a small earthquake.. Kindly proceed carefully ...

 

[Sushant Sharma]

Sushant, I don't know what your plans or intentions are but the ecosystem of Himachal is already quite fragile.. I remember floods last year and with a pair of a 16 and 15 inch driver in a speaker, it seems you are planning a small earthquake.. Kindly proceed carefully ...

Rahul, you started this year's ago when you gave me the first hit (insert Art Blakey here) with the Harbeths.

 

[yogibear]

If you are targeting 2 way with your toys, miniDSP HD will give you a fair idea / starting point and then you can plan your passive crossovers.

Of course serious measurements in your own room will yield maximum sonic benefits but it’s a long / learning journey.

You are lucky to have a large, fitting room for the kind of toys you have acquired. In my case all such toys are hibernating…

 

[Hari Iyer]

@Sushant Sharma - TBH I am jealous of you. I always wanted to own an Altec VOTT as my amplifiers are a perfect match for them. But unfortunately I live in a puny home at Thane which prevent me from buying this legend. Unless something drastically change in.my life the room issues will contine. Till then owning an Altec is a distant dream.

For Altecs it's said that less is more in crossover design. Do not put any crossover on the woofer and allow it to rolloff naturally around 1.5khz. The cone breakups of Altecs are very gentle and should not cause much of integration issues with the CD. For the CD start with a single capacitor at 3KHz so that the -6dB is at 1.5kHz approximately. Go for only WIMA FKPS type or Dynami capacitors. The Altecs are mostly tuned by listening by ear. The measurements and simulations don't have much relevance with them.
Hope this helps.

 

[Yelamanchili manohar]

@yogibear haha..it took some searching and looking high and low but finally I got lucky. Thanks.
@Yelamanchili manohar
thanks Manohar. Yes, these arrived from Hyderabad, Banglaore, Chennai and Vietnam. DTDC, train station pick up, flights and some volvo bus drivers also got to know me in the process. From friends who did not take my calls after hearing about size of packages to other not so close friends who lugged 17 kgs on international flights for me. This hobby I tell ya...
Many thanks for the active vs passive suggestion..very recently a few videos on youtube have appeared on whether to go active or passive. I feel active might be for me in the future because of the know how involved. Passive might be easier to build. Been looking for a tried and tested crossover design which might be easier to build and implement. I do not know how to use dsp and mics etc though u know I must learn that if I want to do justice to these components. How would you have proceeded if you were in my place?

I dont know anything about Altec's, so I would listen very carefully to what @Hari Iyer is saying. He designed and built my speakers, which Iam seriously in love with. And even after 7 years, I have absolutely no itch to change them. So I would follow his advise meticulously if I was going passive.

But I plan on going active, because I sincerely believe that is the next big sonic jump for me. D&D uses a 100 dollar woofer in a 14,000 dollar speaker and it sounds like a 14,000 dollar speaker because of the DSP behind it. Till a few years back DSP was a secretive black art, outside the realm of common folks. But with the advent of modern software like Audiolense it is easy to create active crossovers and the process is automated.

It will become a very lengthy topic on its own, so I wont distract this thread. But if you are interested, please let me know, and I will start a new post in the speakers section how to proceed. But please bear in mind, that this path while giving great results will be limited to streaming via roon or Jriver only. So not ideal for Vinyl or CD playback.

 

[Sushant Sharma]

@yogibear thanks for your detailed comment. Will look into dsp HD. It seems unavailable at the moment on Indian websites. But Hari seems to be suggesting a different approach.
@Yelamanchili manohar thanks. I appreciate your comprehensive reply. I might stick with passive crossover especially since I do play vinyl and do not use roon or jriver or similar. I am all ears with Hari's advice.

@Hari Iyer thanks for your comments. Of the few perks of living in a small town, one definitely is more space and less crowds. I never knew you could drive these woofers without a crossover. Do you mean no crossover/ no caps or inductor there at all? Just connect it straight to the speaker binding posts?

Currently I have been using 8 mfd capacitor on the 288 HF and have toyed with few other cap values. When you say "For the CD start with a single capacitor at 3KHz so that the -6dB is at 1.5kHz approximately."
Could you simplify that further as to what value of capacitor I should use? Many thanks and much appreciated.

 

[Hari Iyer]

@Sushant Sharma - connect the woofers direct to the amplifier binding post with nothing in-between. Start with a 4.7uF capacitor and listen balance of mids with highs. If you find mids to be a little brighter reduce the capacitor to 3.3uF and so on until you find the right balance. If the mids- highs are sounding thin then consider increasing the capacitor value to the next value. Listen to the final balance for a day or two and fine tune as required. You will greatly benefit after one month if you add bypass capacitor to the croossover capacitor. These bypass values are 0.0l, 0.022. 0.047 and 0.22uF. The bypass should be added after one month once you are ok with the overall balance.


For MY OB setup I have used a capacitorless crossover. My woofers are direct, my fieldcoil is having just a 0.33mH and the tweeter terminals are bypassed with a 0.11mH and a 13 ohms resistor.

 

[yogibear]

@Sushant Sharma - connect the woofers direct to the amplifier binding post with nothing in-between. Start with a 4.7uF capacitor and listen balance of mids with highs. If you find mids to be a little brighter reduce the capacitor to 3.3uF and so on until you find the right balance. If the mids- highs are sounding thin then consider increasing the capacitor value to the next value. Listen to the final balance for a day or two and fine tune as required. You will greatly benefit after one month if you add bypass capacitor to the croossover capacitor. These bypass values are 0.0l, 0.022. 0.047 and 0.22uF. The bypass should be added after one month once you are ok with the overall balance.


For MY OB setup I have used a capacitorless crossover. My woofers are direct, my fieldcoil is having just a 0.33mH and the tweeter terminals are bypassed with a 0.11mH and a 13 ohms resistor.

Hari, what a change of approach from a die hard measurement and endless crossover tweaking !!!

I still remember reading your detailed posts on TL builds….

 

[Sushant Sharma]

@Sushant Sharma - connect the woofers direct to the amplifier binding post with nothing in-between. Start with a 4.7uF capacitor and listen balance of mids with highs. If you find mids to be a little brighter reduce the capacitor to 3.3uF and so on until you find the right balance. If the mids- highs are sounding thin then consider increasing the capacitor value to the next value. Listen to the final balance for a day or two and fine tune as required. You will greatly benefit after one month if you add bypass capacitor to the croossover capacitor. These bypass values are 0.0l, 0.022. 0.047 and 0.22uF. The bypass should be added after one month once you are ok with the overall balance.


For MY OB setup I have used a capacitorless crossover. My woofers are direct, my fieldcoil is having just a 0.33mH and the tweeter terminals are bypassed with a 0.11mH and a 13 ohms resistor.

@Hari Iyer thanks again. I tried the values you mentioned and heard the speakers this evening. Perhaps too soon to wax eloquent.. but yes it sounds very good to my ears. Appreciate it. Pls do suggest more such goodness..

 

[Hari Iyer]

Hari, what a change of approach from a die hard measurement and endless crossover tweaking !!!

I still remember reading your detailed posts on TL builds….

I still do measurements and do fine tuning by ear. But imo, drivers like Altecs do not measure and sound the same. The same is also true about my field coil drivers. They too measure and sound very very different. I think most vintage drivers fall in that category. Measurements / simulation might be useful for current generation drivers.

 

[adityapm]

@Sushant Sharma:

These altec drivers are very old, and surely will be severely out of specs, especially in the 'Q' area. Hence what "Hari Iyer" has suggested is the only way to put them to quick use. The cone breakup sound (also known as cone-cry) in the aitec woofers is almost nearly musical. One can always use them directly without any passive components in the path.

Any other higher order/type of crossover will need the drivers first to be measured for their parameters, to calculate the components & the enclosure. But this will cause a lot of heart ache after one realizes the truth.

And yes, don't go for the 817 design. This is PA purposed. Very soon you will wear out by the thrust and projected sounds from the sawn-off horns around the 200 odd Hz. area, and will crave for the smooth transitioning sounds of standard boxes. You have big space. You have 4 woofers. You can go for a A9 concept, say a 30 cub ft (5ft high x2ft deep x3ft wide) sealed box. This will do well for the drivers in their present conditions, and also will justify the space.

Enjoy !

 

[Sushant Sharma]

@Sushant Sharma:

These altec drivers are very old, and surely will be severely out of specs, especially in the 'Q' area. Hence what "Hari Iyer" has suggested is the only way to put them to quick use. The cone breakup sound (also known as cone-cry) in the aitec woofers is almost nearly musical. One can always use them directly without any passive components in the path.

Any other higher order/type of crossover will need the drivers first to be measured for their parameters, to calculate the components & the enclosure. But this will cause a lot of heart ache after one realizes the truth.

And yes, don't go for the 817 design. This is PA purposed. Very soon you will wear out by the thrust and projected sounds from the sawn-off horns around the 200 odd Hz. area, and will crave for the smooth transitioning sounds of standard boxes. You have big space. You have 4 woofers. You can go for a A9 concept, say a 30 cub ft (5ft high x2ft deep x3ft wide) sealed box. This will do well for the drivers in their present conditions, and also will justify the space.

Enjoy !

Thanks Aditya. These altecs woofers sound so good..I can only imagine what one in perfect spec might sound like. I have been using the 416 8c for close to 4 months or so. The compression 288c I have had only for a week or so and though old and beat up it still is very good too.
Quick google search on A9 did not yield too much literature on them but what little I could find it seems they are much bigger in size than what you mentioned. Thanks for the tip, I will try and read up more on them.

 

[adityapm]

Thanks Aditya. These altecs woofers sound so good..I can only imagine what one in perfect spec might sound like. I have been using the 416 8c for close to 4 months or so. The compression 288c I have had only for a week or so and though old and beat up it still is very good too.
Quick google search on A9 did not yield too much literature on them but what little I could find it seems they are much bigger in size than what you mentioned. Thanks for the tip, I will try and read up more on them.

I said "A9 concept", not a replica.

 

[Sushant Sharma]

I said "A9 concept", not a replica.

I understand now. Thanks.

 

[yogibear]

The suggestions by Hari reminds me of two vintage speaker designs where woofer had no crossover. One is famous Wharfedale sand filled open baffle. Check this link:

https://www.inner-magazines.com/audiophilia/vintage/wharfedale-sfb3/

The second is offered by Madisound utilizing Seas drivers based on A26 vintage speakers:

Seas A26 10" 2-way Kit Pair (based on the classic A25)

Seas A26 10" 2-way Kit Pair - a new spin on a true classic! Price is for a PAIR Designed by Håvard Sollien & Diego Ivars at the SEAS R&D laboratory. Seas of Norway and Madisound are excited to provide the A26 speaker kit. This kit utilizes the A26RE4 10" classic paper cone woofer and new...

www.madisoundspeakerstore.com

Both are interesting articles but serious designers don’t approve either of them. I have never personally listened to any or experimented with such simple crossovers but am quite curious as why some are die hard fans.

 

[Hari Iyer]

The second is offered by Madisound utilizing Seas drivers A26

I have used the seas driver in a TL enclosure but have used a 1st order on that as it was a 3-way speakers.