120studio.com 4/29/2015

Copyright 2015.  All rights reserved.


8


Intro

If you're into vintage audio, you'll probably encounter Zenith Allegro speakers sooner or later.  The question is, do they work well?  Are they worth having? 

If you have these speakers, can they be fixed or upgraded? 

Let's find out.




A Quick Note


This article is made possible only by the support of readers like you, when you use the links on here to purchase your gear.

The small commissions from sales are what allow me to keep this site going.   Thank you in advance for your help.


In This Article


Some Specs

Dimensions & Weight

General Characteristics


Sound Quality

Frequency Response

Re-Capping

Blown Speakers


Price / Value

Conclusion







Some Specs


Cabinet Material:  Particle Board
Capacitor:  3 µF, 50V AC (Allegro 2000);   4 µF, 30V AC (Allegro 3000)
Crossover Frequency:  2,500 Hz
Dimensions:    There are two sizes for the Allegro 2000's;  see below.
Frequency Response:  50 Hz - 15,000 Hz
Impedance:  8 ohms (but some of them are reportedly 16 ohms)
Made In:  USA, with some components from Japan, Mexico, and possibly Hong Kong
Power rating:  40 watts RMS / 100 watts max.
Sensitivity:    Unknown but probably 89 or 90 dB
Tweeters:  3 1/2";  may be different brands, but usually Foster (Fostex)
Weight (each):   see below
Woofer size:   8" (Allegro 2000);  10" (Allegro 3000)
Woofers:  AlNiCo, brands may vary
Years of Manufacture:  1970's




Dimensions & Weight


Zenith made the Allegro 2000's in at least two different sizes.

Small version: 

Height.... 20.6"
Width..... 13.1"
Depth...... 8.9"


Large version: 

Height.... 22.5"
Width....  14.5"
Depth....   8.6"

These are the ones I know about for sure;  Zenith could have made different variants with different dimensions.

I'll update this with the weights as soon as I get the chance.




General Characteristics

Zenith Allegro was actually a line of audio gear, which included everything from 8-track players to full-on home stereo consoles.  This was not "high end" gear by any stretch of the imagination;  it was aimed more at the average consumer.     (There are even Zenith Allegro DVD players today.)

The goal with this product line was to give high-quality sound while being affordable.  That required some design trade-offs.  If you want to sell something cheaply, and you increase one quality, you have to decrease another.  Sound quality went up, while construction quality went down somewhat.

Even by 1970's standards, the speaker cabinets were a bit cheesy.  While many manufacturers were using real plywood, Zenith was already using particle board for many of the Allegro speaker cases.

If you can look past the cheap construction, a lot of Allegro speakers actually sound pretty good.

Many Allegro 2000's were stapled and glued permanently shut.  The front grills don't seem to be removable, either.   They are glued in place.

The backs have a note that advises taking them to a service center if they need repair.  I can only guess what special tools the service center would have utilized to get into those speaker cases.  Quantum teleportation?  I don't know. 

The backs have hard-wired speaker cables-- not really cables, just thin wires-- which help give the speakers an overall feeling of cheapness.  That's not always an indicator of poor sound quality, though.   (In this case, it's not.)   If you can get the backs open, you can always rig these up to have actual wire terminals.  

(Back to top)




Sound Quality


These speakers are almost the exact opposites of the Sansui SP-30's.  The Allegros have a lot of bass and treble, but not much mid-range.   These speakers are great for people who like V-shaped equalizer bands. 

You may want to bypass the tone control or flatten your equalizer a bit on your system to get the best sound out of these.   Then again, it depends on your room acoustics.

These speakers provide clear sound without any major artifacts that I can notice.  They have a nice "open" sound to them, at least compared to some of the cheap vintage speakers I've tried over the years.






(Back to top)



Construction & De-Construction

I'll be putting this in a separate article, because this can turn into an involved project.  Zenith designed the speakers so you cannot even get to the internal components... well, I'll show you how to do that anyway.  And put them back together.  We'll get to that later;  for now, let's talk more about the speakers.

(Back to top)




Frequency Response


50 Hz - 15,000 Hz.

People with good hearing can generally hear to 20,000 Hz.  Even older listeners can usually still hear to 16,000 Hz.    (The very high frequencies start to go first when you get hearing damage.)

Allegro 2000's have a "Brilliance Control" switch.  This either enhances the high frequencies ("+"), or suppresses them ("0").   It sounds to me like an upper-mid boost;  not quite the highest frequencies.




Groovy.

Yep, I should have cleaned the dust from these a little better.  But they work.




(Back to top)




Re-Capping


Like the Sansui SP-30, the Allegro 2000 uses a single capacitor in the crossover.    The Allegro 2000's have a "Brilliance" crossover, which also uses a couple resistors.  You probably won't need to replace these;  just the capacitor.

Many of the Allegros have electrolytics, but I'm not sure if they all do.  I've seen at least one pair that had what looked like paper or film capacitors, although they could have been a different type of electrolytic.   Film caps basically never go bad, so if that's what your speakers have, great. 

If they're electrolytics, replace them with polypropylene capacitors.  I'd get a pair of these.  For the specs they provide, the price is right.

Opening the cases:  you might be lucky enough to get a pair of Allegros that have screws in the back panel.  Many were stapled and glued together, which means you can't easily open the cases.   It can be done without scrapping them, but it's very time-consuming.  I'll detail the process in a separate article.

Long story short:  you'll have to cut out the back panel, then replace it when the upgrades are done.   I figured out a good way to do that, but you'll need a weekend when you don't have any other plans.

One reason why so many Allegro speaker drivers end up being used in other speaker projects... is because a lot of people knocked the cases apart.

(Back to top)










Blown Speakers

You can test the ohms with a multimeter, but you won't know if there's partial damage that could degrade the sound.

If you're looking to buy a pair of these, ask the seller if they've been tested.   Probably the main selling point of these speakers is the Foster / Fostex tweeters, so obviously you'll want to make sure these are still good.

You don't absolutely have to remove the front grill to replace the drivers, but you will have to open up the back of the case (even more difficult). 

The drivers are fastened in with screws from the front of the enclosures, but each screw is held in place with a nut from the inside of the case.  They use a black tar-like material to keep them from vibrating loose. 

If your speakers crackle a bit, but they still play sound, odds are it's a bad capacitor instead of a blown speaker.

(Back to top)






Price / Value

These are not expensive speakers.  Their construction quality is a major factor in the relatively low value.  If someone doesn't have to go through the hassle of listing them online and shipping them, a realistic price would be $5 to $25 a pair, depending on condition.

Online, you might see people asking upwards of $50 to $75 pair, not including shipping.  For that price, make sure the person has verified they sound perfect and everything is cosmetically good.

And for that price, they should be the kind that have screws holding on the backs.  If they have stapled & glued backs... you're looking at hours to get them apart without breaking up the cases.

These are not exactly light-weight speakers.  Shipping could add $30 to $70 for a pair.  That doesn't bother some people;  to them, it's better to pay the shipping cost than spend the time and gas driving to places yourself.    Some people don't live near any decent stores, either, so it starts to make sense.

If you get a pair with Foster tweeters and the capacitors haven't gone bad, they probably sound as good as any modern pair of $100 speakers. 

Still, though:  because of the construction quality, I might go for a pair of these before I'd seek out a pair of Allegros at $100.  Then again, sometimes you just want the real-deal Seventies stuff. 

Please help support my site by purchasing your Allegro speakers or anything else through this link.

(Back to top)




Conclusion


Zenith Allegro speakers are not expensive, and maybe they're not built that well... but then again they're not as bad as some people make them out to be.   If you can look past the cheap construction, they have actually very good sound. They are great for loud music.

If you get a good pair of these, you may never need to take them apart anyway;  and if you do, you'll have a (maybe) fun project for a weekend or two.

I hope you found this page useful, informative, or entertaining.  If so, please help me out by purchasing your stuff through these links.   Your help is greatly appreciated and is the only way I can keep this website going.

Thanks for visiting this page!








Contact me:

3 p o.t o . 1 2 0 s t u d i o.. c o m


This won't directly copy and paste.  Please manually type it into your mail program.
No spaces between letters.





Home Page


Site News



Disclaimer

All photos on this site are Copyright 2010-2015.  Please feel free to share links to this site.  However, copying or re-distributing page contents or photos for any purpose, electronic or printed, is prohibited without express written permission
.





 



Back to Top of Page