Hi !

AL 621, AL CS21, AL 251 & AL ATP3 Here!

haha...Don't ask me why so many but in the courase of upgrade, got so many....

As to preference...still prefer listening to the AL621. Damn...these got the best speakers so far....coupled with a Prodigy soundcard, its as close to reference speakers as you can get.

Hi...AL621 user here... got it from a garage sale for RM150.

Previously using AL CS21 - at first thought it sound great - good treble and midrange although to my ears a bit wolly. Bass is OK for its range.

Then I plug in the 621 and ....Wow....

treble is clear, marvelous midrange ...and bass is solid without the boominess...And the imaging is very open .... Paired it with a M-Audio 192 sound card....so the 621 is good enough for my home studio PC...

Was previously using Promedia GX2.1 - Terrific bass but the satellite speakers way too sharp for music listening and mid-range almost none existent so sold it off after two days.....

Hi. Altec Lansing 621 Owner here. Yes, it's an old model but still have the best sound, especially now when it is connected to a recently upgraded Audiotrak Prodigy HD2. At first I thought the sound from the speakers was quite bright when it was paired with Audiotrak Prodigy 7.1LT but after plugging in to the Prodigy HD2....

first impressions is that the pitch is truer... maybe it's my ears but the Prodigy 7.1LT don't sound pitch correct....soundstage now is wider, and there are quite a lot of details now...

I guess the AL621 is an old model and since discontinued...but it maybe the ideal combination with the Prodigy HD2 now... I pray the AL621 dont die off on me....

Hi guys...

Got a Altec Lansing CS21 and Altec Lansing 621 here. Paired them with a Audiotrak Prodigy HD2 (modded with LME49720NA OPAMPS).

Since I have a number of spare LME49720NA around, I decided to open up the CS21 and change the stock OPAMPS NE5532 to LME49720NA. I solder sockets so that I can swap them in the future.

You can see the picture below.

Anyway, Here are my impressions (I think a detailed writeup later) of the sound after 1 month of breaking in.

Test materials:

Hotel California -Eagles (Hell Freezes Over album - XRCD version)
Bloody Sunday - U2 (War - Mobile Fidelity Sound Lab CD)
Blue TRain - John Coltrane (Bue Train - Mobile Fidelity Sound Lab CD)
Miles Davis - Kind Of Blue (2003 remastered, SACD edition)
Beethoven String Quartet no 7 - Talich Quartet
Sheffield Drive - Sheffield Lab

Ripped to Hard Disc and played back thru Foobar2000 via ASIO.

The bass adjustment knob on the subwoofer is set to the default ie Middle of the line.

Stock OPAMPS (CS21)
Bass is overwhelmingly strong, Mids are very pronounced though a bit bright in the upper mid range
and the trebles are bright. Nice separation but lacking in depth and imaging.

LME49720NA OPAMPS (CS21)
Bass is much tighter, with a solid feel. The MIDs are smoother but is still noticeably birght in the upper mid range. The trebles have more body and air. Overall sound stage have expanded and more depth to the sound. You can sense the music playing inbetween the space of the speakers and extending beyond. Overall image have more body to them. Details are freaky....hear a lot more intrumental details than before....

Pianos, violins and guitars have body to them. Drum Kicks and Snares are tangible, with a solid Thump to the BAss Drum Kicks. The Snares have a tight whack, can hear the reverb in the room.

It's a nice sound but I feel as though the sound is a bit aggresive in the upper mid range for my taste.

I also compared this to the Altec Lansing 621. The 621 is quite neutral with a nice blend of the image, but I feel is lacking in body and imaging I get from the modded CS21. Am planning to mod the 621 with the LME49720 OPAMPS. I wonder if the imaging and body of sound will improve.

Brought back Alexis M1 Active MkII monitors from my studio and compared them .... Must say that the Modded CS21 comes quite close to the MKIIs... .....But of course there are somethings that the MKIIs will definitely sound better ....









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Yes, it's still the best altec lansing PC speakers there is. I have the 621 version. Paired it with the Audiotrak Prodigy HD2. Still sounds great after almost 5 years. Have another set as backup in case this one goes kaput...

I have been using Altec Lansing 621 for almost 4 years until a recent accident made the speakers going without the subwoofer playing. Must some internal PCB wiring problem. Have been modding it replace all speaker wires with Canare cables and changed to rubycon and nichicon caps salvaged from an old Aiwa hifi set. It was really a great speaker acquring legendary status in sound quality. Full, warm, body of tone....and depth and spread of stereo image is amazing.

Since the subwoofer died, I bought the newer MX5021, especially after reading most comments to say this is quite a good balanced speaker. When I first start it up, I thought it sounded very thin using the stock cables, so I switched the satellite speakers to the old Canare cables I have lying aorund. Better improvements and the sound acquires a little more body to it.

Actually MX5021 still sounds thin to me at the moment. The sound image seems to be compressed in the middle and the stereo spread is narrow, where it used to be very wide with the AL621. Perhaps a few days breaking in might help. Or a modding to the caps.

The AL621 is such an excellent speakers that compares favorablly with the Alesis MKII monitors in my office. I wonder if anyone knows how to repair a broken PCB trace...

Update 30/06/09

I couldn't wait and not being able to stand the thin and harsh sound from my MX5021, I decided to change some of the caps in the Amplifier unit and added two caps to each Satelite speakers.

After the changes, the sound quality has changed immensely. The sound has more body to it and very immersive. The treble is now clear. Details jump out at you.

There are still some things that I supposed could make it sound even better but for now I am satisfied until I can get hold of more components.

This is basically what I use as a guide to mod the speakers - http://www.techenclave.com/guides-and-tuto...l#content_start.


I didn't really follow the caps recommendation. I used the same values except changing the stocks to better brands such as Nichicon and some Black gates salvaged from various hardware lying around.

Update 02/07/09

Still finding the speakers sounding thin in orchestral music, I decided to go ahead and mod the speakers again and change the OPAMPs inside from 4558c to NE5532 salvaged from a Prodigy HD2 card. The impression now is much better. Clarity and body and depth to the sound signature. There are details i never noticed before. Really good upgrade and I am happy with this.

I believe what is on the reviews all over the net were refering to the older batch of MX5021 which apparently sounded superior. The one I bought is a cut cost 2nd version which really sounded harsh and thin to my ears, makes me wonder how AL can still maintain the THX certification when they changed the system design.

This post has been edited by damieneo: Jul 2 2009, 03:43 PM