Altec A7 build

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June 26th, 2012, 12:01 AM
santhoshl

Altec A7 build

Hi fellow Altec Enthusiasts,
I would like to share with you my Altec Lansing A7 build. It is not exactly complete [staining still pending and also a few tweaks], but is functional and will be an ongoing project :). I have based this on the Altec 828 cabinet plan available on the Heritage site.

References:
In addition to the original plan, I have also used the plan on MFK Projects as a reference.
This Horn Flare diagram was of great use. Thanks mfk-projects, if you are reading this.
The sound practices article shared on Jeff Markwart's site was very useful in building the Altec A7s to sound more Hi-Fi (I have never heard the original, as they are very rare here in India).

Drivers:
LF: 416A refurbished with cones from GPA (16ohm)
HF: 802-8g with 811-B horn (8ohm)

Crossover: 1st order, crossed at 1Khz. Capacitors are "KBG" Russian PIO Military grade. Resistors are el-cheapo ones I could find, plan to source some Mills resistors from Parts Connexion.

About the partnering gear:
Source:
1) Turntable(s):
i) Project Xperience II with Carbon Fiber Tone Arm and Ortofon Rondo Red Cart
ii) Pioneer PL-15 with original cart and JICO stylus
2) CD Player: Marantz CD-94

Amplification:
Currently running it with an ADCOM GFA-535 MkII amp and GFP-345 Pre. In the process of selecting a SET tube amp.

I have used Altec 416a driver because that is what I had and also the sound practices article recommended a 416 more than a 515.

I would like to thank this Altec Forum for the valuable information in here, my friend and Fellow Member Rajiv for pointing me to this forum and offering tips at every stage in this project. Also Panomaniac for answering my questions on the flare design :).

Here are some pics shot over the last two months. The entire build has been documented on my DIY site : Home to the Indian DIY'er and Hobbyist . Appreciate your feeback and suggestions.

http://www.hostboard.com/forums/hbmc...2012/06/42.jpg

http://www.hostboard.com/forums/hbmc...2012/06/43.jpg

http://www.hostboard.com/forums/hbmc...2012/06/44.jpg

http://www.hostboard.com/forums/hbmc...2012/06/45.jpg

http://www.hostboard.com/forums/hbmc...2012/06/46.jpg

http://www.hostboard.com/forums/hbmc...2012/06/47.jpg
June 26th, 2012, 12:14 AM
cradeldorf

Re: Altec A7 build

Nice work Buddy, Keep us up on any new developments. Also welcome to Vintage Altec Land. :)
June 26th, 2012, 01:20 AM
mah

Re: Altec A7 build

Very nice. :) May pass the WAF test. :wink2:
June 26th, 2012, 08:44 PM
santhoshl

Re: Altec A7 build

Quote:

Originally Posted by cradeldorf

Nice work Buddy, Keep us up on any new developments. Also welcome to Vintage Altec Land. :)

Thanks cradeldorf for your kind words :)

Quote:

Originally Posted by mah

Very nice. :) May pass the WAF test. :wink2:

Thanks mah, she likes it. What she does not know yet is that I will be adding 805 horns soon ;)
June 26th, 2012, 09:47 PM
bowtie427ss

Re: Altec A7 build

Beautiful workmanship!

I really like how the system fits in that space!

You need a preamplifier, the Adcom is not up to the standards of the rest of your system, not even close.
June 27th, 2012, 12:50 PM
santhoshl

Re: Altec A7 build

Quote:

Originally Posted by bowtie427ss

Beautiful workmanship!

I really like how the system fits in that space!

Thanks bowtie for your encouraging words.

Quote:

Originally Posted by bowtie427ss

You need a preamplifier, the Adcom is not up to the standards of the rest of your system, not even close.

I plan to listen to a few SET amps with the A7s before I zero down on a tube amp. I tried it with a SET amp running 45 tubes, it sounded magical.
June 27th, 2012, 02:09 PM
Altec Best

Re: Altec A7 build

Beautiful work ! Nice job ! I noticed you are using 16 ohm woofers and 8 ohm HF drivers.I'm curious on the mismatch ?
June 28th, 2012, 10:15 PM
Panomaniac

Re: Altec A7 build

With 16 ohm woofers you won't need as much attenuation for the 8 ohm horns.

Very beautiful build, bravo! I think you will be very happy with the 805s. You really should close up those ports some, you'll get more bass.
June 28th, 2012, 10:43 PM
Alien_Shore

Re: Altec A7 build

Quote:

Originally Posted by Panomaniac

With 16 ohm woofers you won't need as much attenuation for the 8 ohm horns.

Very beautiful build, bravo! I think you will be very happy with the 805s. You really should close up those ports some, you'll get more bass.

I thought the same thing. And yes, great build. Thank you for sharing with us.
June 28th, 2012, 11:51 PM
cradeldorf

Re: Altec A7 build

I'm gonna lean the other way and say I bet the bass is pretty nice. :)
June 29th, 2012, 12:22 AM
VolvoHeretic

Re: Altec A7 build

Beautiful Altecs Santhoshi, They look wonderful.
June 29th, 2012, 12:43 AM
santhoshl

Re: Altec A7 build

Quote:

Originally Posted by Altec Best

Beautiful work ! Nice job ! I noticed you are using 16 ohm woofers and 8 ohm HF drivers.I'm curious on the mismatch ?

Quote:

Originally Posted by Panomaniac

With 16 ohm woofers you won't need as much attenuation for the 8 ohm horns.

Very beautiful build, bravo! I think you will be very happy with the 805s. You really should close up those ports some, you'll get more bass.

Quote:

Originally Posted by Alien_Shore

I thought the same thing. And yes, great build. Thank you for sharing with us.

Thanks friends, I am glad you liked it. Though I love to DIY and have been following speaker builds for several years, this was my first speaker build and I must thank you all for the knowledge I have gained from reading this forum. About the HF being 8ohm, I did not have much of a choice. I searched for almost 3 months after I got the 416s and finally managed to find a pair of 802-8gs in pristine condition in Singapore while on business travel. Not know much about these things, I too was worried and wanted to get 16ohm frams but was hesitant because my 802s have the original thinner? diaphragms. But I was lucky to have a friend, Rajiv (not sure what his handle is here) guiding me at each phase. He is an exprienced audiophile and an Altec enthusiasts. He listens to Altecs too (built using 515s and 288s with Stereo Lab Tractrix horns with a 2A3 SET amp). Like Panomaniac mentioned, Rajiv too told me that I should be fine with the correct attenuation and pointed me to some online calculators. After, a few changes in Lpad values, I zeroed in on what sounded right to me :) .
June 29th, 2012, 01:01 AM
santhoshl

Re: Altec A7 build

Quote:

Originally Posted by Panomaniac

You really should close up those ports some, you'll get more bass.

Quote:

Originally Posted by cradeldorf

I'm gonna lean the other way and say I bet the bass is pretty nice. :)

I am getting ample clean bass which I think could be because I am using 416s and not 515s. I will definitely try reducing the ports and post my findings here.

I also want to try with a pair of 515s that I have, but they need new cones and that will take longer as I am saving up to buy suitable amplification to replace the Adcoms :) .

Quote:

Originally Posted by VolvoHeretic

Beautiful Altecs Santhoshi, They look wonderful.

Thanks VolvoHeretic, thats a lovely Volvo you have in your avatar. Kindly PM me a link to larger pics. Thanks in advance :)
June 29th, 2012, 03:07 AM
aditya

Re: Altec A7 build

Quote:

Originally Posted by cradeldorf

I'm gonna lean the other way and say I bet the bass is pretty nice. :)

I will also say the same.

It is true that when the port size reduces it lowers the tunning, and there will be an extension to the the LF. But the 825/828 is not a straight forward BR design. It is with a FLH. How on earth anybody can match upto that extra gain unless a "lump" is created by a higher tunning ? For me the blending between the LF horn, the port and the HF horn always got lost whenever I tried it. The LF horn became clearly audible. Ofcourse I am talking about a situation of no equalizers in the path.

Another point to note here is that, while the Altec stable was full of BR designs and many with port holes almost like slits, why the designers tuned the 825/828s so high ? I don't think they missed anything here on this matter particularly ?
June 29th, 2012, 03:11 AM
aditya

Re: Altec A7 build

Very good setup there, Santhosl.....congratulations.
June 29th, 2012, 04:24 AM
Altec Best

Re: Altec A7 build

Quote:

Originally Posted by Panomaniac

With 16 ohm woofers you won't need as much attenuation for the 8 ohm horns.

Very beautiful build, bravo! I think you will be very happy with the 805s. You really should close up those ports some, you'll get more bass.

Are you sure ? You mean 16 ohm HF drivers and 8 ohm woofers will need less attenuation.With less resistance the HF horns will receive more power.. Crossovers (attenuation) were never my strong suit though.So I'll defer on this one..
June 30th, 2012, 10:19 AM
VolvoHeretic

Re: Altec A7 build

A7's can make plenty of low bass without EQ. You just have to be sitting at least 100 feet away from them. :)

At that distance, the lows magically appear, the mids get tamed, and with a gaggle of Piezo tweeters, the cymbals and cow bells shine through.
June 30th, 2012, 11:59 AM
Panomaniac

Re: Altec A7 build

Quote:

Originally Posted by Altec Best

Are you sure ? You mean 16 ohm HF drivers and 8 ohm woofers will need less attenuation.

Ooopps! Yes, that IS what I meant. And it's how I run my system. (must have been the rum and coke talking)
June 30th, 2012, 12:47 PM
Altec Best

Re: Altec A7 build

Quote:

Originally Posted by Panomaniac

Ooopps! Yes, that IS what I meant. And it's how I run my system. (must have been the rum and coke talking)

No Worries ! That's what I thought you meant.. Yes 16 ohm HF drivers and 8 ohm woofers will give the desired attenuation. :Big smile: I need to come by and catch up with some rum and cokes, and a smile, Or a Vodka Martini with lots of Olives :wink2:
June 30th, 2012, 12:52 PM
Panomaniac

Re: Altec A7 build

We have all of the above, along with Altec gear. :D
June 30th, 2012, 01:04 PM
Altec Best

Re: Altec A7 build

One other thought. He has the opposite so he will have some serious attenuation to do IMHO.His drivers are 16 ohm woofers and 8 ohm HF drivers (802-8G'
s)

@Pano BTW - I like to travel with lots of my own gear as well ! Then we could pool our stuff and put together something nice... Sounds like lots of FUN !

How far away are you ? :Big smile:
June 30th, 2012, 09:34 PM
aditya

Re: Altec A7 build

@ VolvoHeretic

Yes, you are quite right there.
Greater listening distance & higher power brings out the best in the bass region for the A5/A7.
Some design...
June 30th, 2012, 09:55 PM
aditya

Re: Altec A7 build

Quote:

Originally Posted by Panomaniac

Ooopps! Yes, that IS what I meant. And it's how I run my system. (must have been the rum and coke talking)

I liked it b'coz you are not alone there. In fact initially I had replied to AB's post saying that he was wrong (sorry AB...smile), & you were right, and I had also mentioned it as '16 ohms woofer & 8 ohms HF", but quickly realised my fault and removed the reply as it was unnecessay. However it seems you both are going to have a nice time soon with each other and the Altecs. I can't join but my good wishes will.

Strange creatures these A5/A7s are. Even mere discussions about them bring out the best in human beings ! Probabely b'coz after switching many times between hair tearing moments to moments of nirvana, one gets seasoned out.

Aditya
June 30th, 2012, 11:04 PM
amandarae

Re: Altec A7 build

Very nice!!!

I use 416-8B's and 288C's(16 ohms) on mine and no problem with attenuation even with the 8 ohms LF and 16 ohms HF XO. I will recommend discrete attenuator circuits once you decided the right level using Lpads as to me, the difference between the two is not subtle.

Preamps you say? I will recommend a Supratek if you want transformer coupled. Another one since you are into DIY heavily , I am sure you can build either a type 76, 56, or 26 preamp.

Abe
July 1st, 2012, 12:16 PM
Altec Best

Re: Altec A7 build

Quote:

Originally Posted by aditya

I liked it b'coz you are not alone there. In fact initially I had replied to AB's post saying that he was wrong (sorry AB...smile), & you were right, and I had also mentioned it as '16 ohms woofer & 8 ohms HF", but quickly realised my fault and removed the reply as it was unnecessay.

Yeah I was wondering were that post went ? :Big smile: No Problem Aditya ! We all make mistakes, and I probably make more than anyone ... :p
July 1st, 2012, 01:56 PM
Panomaniac

Re: Altec A7 build

Quote:

Originally Posted by aditya

I Probabely b'coz after switching many times between hair tearing moments to moments of nirvana, one gets seasoned out.

Yep, I think you've hit the nail on the head! :inkblot-smile:
July 1st, 2012, 03:52 PM
GM

Re: Altec A7 build

Quote:

Originally Posted by Altec Best

One other thought. He has the opposite so he will have some serious attenuation to do IMHO.His drivers are 16 ohm woofers and 8 ohm HF drivers (802-8G's)

Stack and series wire another pair of 511s on top of the existing pair to create a ~350 Hz horn with mids and attenuate just one each of the additional HF up high and add CD horn EQ if need be, i.e. a poor man's 805/288 combo except with a better, more extended HF response. GM
July 1st, 2012, 11:57 PM
santhoshl

Re: Altec A7 build

Quote:

Originally Posted by aditya

Strange creatures these A5/A7s are. Even mere discussions about them bring out the best in human beings ! Probabely b'coz after switching many times between hair tearing moments to moments of nirvana, one gets seasoned out.

Aditya

Very true and I am enjoying every bit of the journey and also learning from all your posts.

I will post the exact lpad values I am using later today.
July 2nd, 2012, 12:54 AM
santhoshl

Re: Altec A7 build

Quote:

Originally Posted by amandarae

Preamps you say? I will recommend a Supratek if you want transformer coupled. Another one since you are into DIY heavily , I am sure you can build either a type 76, 56, or 26 preamp.

Abe

Thanks Abe, appreciate if you could share some links. I am definitely considering DIY.

Quote:

Originally Posted by GM

Stack and series wire another pair of 511s on top of the existing pair to create a ~350 Hz horn with mids and attenuate just one each of the additional HF up high and add CD horn EQ if need be, i.e. a poor man's 805/288 combo except with a better, more extended HF response. GM

Very interesting. Thanks GM.
July 6th, 2012, 10:58 PM
santhoshl

Re: Altec A7 build

Hi Friends,
I received the 21216 throat adapters yesterday. Now the wait for the 805s begins :)

Here are some pics:

http://www.hostboard.com/forums/hbmc...2012/07/14.jpg

http://www.hostboard.com/forums/hbmc...2012/07/15.jpg

http://www.hostboard.com/forums/hbmc...2012/07/16.jpg

I must thank Altec Best for pointing me to these on eBay at the right time on another thread. Cost me ~$90 + shipping to India ($50). The seller found 6 of these lying in a barn and listed them separately which worked out well for me, chances of winning were higher.
July 7th, 2012, 12:10 AM
Altec Best

Re: Altec A7 build

Your Welcome ! I'm glad it all worked out for you... :smile2: