Dynaco A-25, the Large Advent, and JBL Century L-100: which one nad the best sound??

I worked at an audio store in Anaheim, CA in 1975-6 when the original Advent, JBL L100 and Bose 901 were dominating the market. I heard them (and Dahlquist, Ohm, and ESS) all day long.

I never heard the Dynaco speakers but I had a pair of hand-built floorstanders with dual Danish-built Peerless textile dome tweeters for 12 years.

L100s are physically well built (except for the ubiquitous rotting foam surrounds almost everybody had back then), but the horizontal bookshelf design, adapted from the vertically oriented 4311 studio monitor, was optimized for controlled, almost nearfield listening and had no consideration for (or maybe awareness of) in-room power response. By today's standards, the L100's crossover points are ridiculous--1500 Hz between a 12" woofer and 5" midrange, and 6000Hz between 5" midrange and the 1" tweeter. A 12" woofer starts beaming at 1125 Hz and a 5" midrange starts beaming at 2700 Hz. This means there are significant off-axis suckouts at 1100-1500 Hz and more than a full octave beaming between 2700 and 6000 Hz. If you move off-axis these suckouts give you that "cupped hands" sound. The advantage is that it translates into high power handling capacity.

The Advent, OTOH was designed specifically for linear in-room power response, and Kloss & co. paid special attention to driver size vs. crossover point. The Advent woofer, while mounted in a 12" frame to maximize cone excursion, had a 6.5" cone crossing over to the tweeter at a very low (for a tweeter) 1KHz. A 6.5" diaphragm doesn't completely beam until 2250 Hz. Therefore, the single 1KHz crossover point was not beaming in the slightest. That very low crossover almost certainly accounts for the frequently blown tweeters that came back to us from customers. Advents sounded good on a wide variety of music. Good on rock if you had the amp power, and great on classical, jazz, and pretty much everything else.

The Advent also had *real* bass--audible down into the mid 30Hz region. The L100 started rolling off around 100 Hz and was pretty much MIA by 50 Hz. It seemed to have strong bass because it was a 12" diaphram making big waves at the frequencies it *could* reproduce.

The L100 had a punchier, immediately engaging sound. It was way more sensitive. It could kick ass with a 40 wpc receiver and do pretty good on 20 wpc in a dorm room. The Advent really needed 100-150 to come alive, but we were just starting to learn about that back then, thanks to Bob Carver.

However, let's consider something: In the mid-'70s the L100s were $560/pair ($2500 in today's money). The Advents were about $200/pair. You could have bought a TRIPLE stack of Advents for $40 more than a single pair of L100s. In that showdown, and given that double Advents were already legendary by then, triple Advents would easily have beat the JBLs, with triple woofers making audible bass down to 32 Hz and three tweeters sharing the upper mid/treble load. The also had a 3-way switch on the back to boost the tweeters a bit. 

To erj, that was a nice amp you had in McIntosh, and also Marantz receiver. However, I am NOT sure I totally agree with you about the Advents. A pleasant sounding speaker with an excellent midrange and clean bass, however, classical and jazz ( not elevator jazz)  were limited in texture and range by that god awful tweeter the large Advent used. At least, the Dynaco  A-25 incorporated Seas drivers which were the best in the world at the time and in my opinion, still are.  What was your overall opinion of the Dynaco's??   Thanks for the reply      

Wow!  Back in the day I had all three of those speakers, driven by a McIntosh MC225, then a McIntosh MC275 and finally a Marantz 2275 receiver.

If you listen to a lot of rock & roll the JBL's would be my first choice.

If you listen to all sorts of music (i.e. classical & jazz, vocals, etc.), I'd say the Large Advents would be my first choice.

Had the DYNACOS , then the ADVENTS, then EPIs, and then JBL-100s back in my young days at university.

JBLs reign supreme .... Not even close.

BUT .., couple qualifiers:

(1)  these were a "California" sound speaker ( Google the term ...) with heavily spiked frequency curve In the  treble and bass to accentuate a tailored pop and rock music presentation  of the era.

(2) none of the OPs suggestions will match up to current era standmounts with their improved design build,  and crossovers ... Full stop..Remember that all of these geezer-rock era speakers  have ultra-cheap basic spring-loaded speaker binding posts limited to 18-gauge zip cord cheap and crappy speaker cable posts that need replacement, and likely need speaker surround re-foaming and maybe even new caps .

if you favour nostalgia and favour 70s hard rock played loud, the JBLs will be your boomy bass party speaker... No problem.

If you are looking for a non-coloured balanced musical presentation especially with all the other music genres, look elsewhere .

The Dynaco A-25's were my first "hi-fi" speaker, with a PAS3x and a Stereo 70.  I went from there to Large Advents, then to stacked Advents.  A roommate during that last time had JBL L-100's; he put them in storage while we lived together (for about 9 mos).

2 pairs of large Advents, stacked are even better  HP in TAS loved them.  The JBL's are great for rock but not so much for Jazz or Classical.  The JBL doesn't need too much power to drive them where the Advents and Dynaco do.  If you like all kinds of music, the large Advents would be the best bet.

The JBL L-100 Century was my first pair of real speakers.  IMHO, one the best rock-n-roll speakers ever made.

Wish I still  had them...

I owned both Dynaco A-25 and large Advent at one time in the distant past, but heard the JBL L-100 many times in friends' systems. I know I liked them all and would have been happy with any one of them at that time. As faded as my memory is I believe I might have liked the JBL the best...??? Best, Rob