LESLIE 147


On Different Woofers And Horn Drivers Used In 122 / 147 Type Leslies

The list below includes woofers and horn drivers originally used in tube amp based Leslies (two-speed models such als 122 142 145 147 251), quite some aftermarket replacements, and those used in recent editions like 122a/xb 147a, 3300. Since the decision regarding replacement types often was quite an individual one, there's no way that a list like this could ever be complete. Still, I thought I'd share the information I was able to gather during my search for optimum Leslie sound.

The original horn driver used in most vintage Leslies - even in those dating back to the 1940's, but also in transistor Leslies up until the mid 70's - was the Jensen V21; only in some later transistor models did they switch to other types. In the more recently made Leslies, they've been trying out different types with mixed success (types being overly bright, or simply breaking down after a wile) but as of 2012 or so seem to have settled on a reliable and good sounding one. (Manufacturers and types are not easy to track down, since these are no longer genuine types using standard manufacturer codes, but OEM products with mostly no markings at all). In vintage tube Leslies, anything different than V21 is most obviously non-stock.

As for woofers, Leslie already had their latest single speed designs fitted with Jensen P15LL (Alnico magnet) and continued to use them up until 1965, after which they switched to Jensen C15L (ceramic magnet). Two-speed Leslies (122, 147, and related designs) were introduced only in 1963, so the period during which these cabinets were actually fitted with P15LL - the most desireable woofer to many people - only lasted roughly 3 years. After 1971, the C15L's used in Leslies were made by a different company named Rola, which actually was a division of Jensen, though. Today, Jensen makes re-issues of their classic speakers, but also other manufacturers like Weber offer types leaning towards the vintage designs. The woofer that Leslie uses in their current models is an OEM version of the Eminence Delta 15b.

Over the decades, power ratings and efficiency of the types used have increased considerably. Both P15LL and V21 were only rated 35 Watts, where today's horn drivers and woofers used can handle 100W and 400W respectively. Also, the V21's frequency range actually rolls off at 4KHz, where those of any modern driver extends well beyond that, meaning a much brighter sound by default.

The amplifiers in vintage 122 / 147 type Leslies were rated 40W, later transistor models went up to 120W, the current model 3300 even boasts 300W solid state amplification, including a tube preamp. The 122a/xb/147a reissues, however, use the exact same 40W amplifier design (even the chassis) as found in vintage all tube Leslies.

Aftermarket Replacements And Tweaks

Depending on the amount of abuse of a Leslie over the years, drivers or woofers would eventually blow. Next to getting a replacement diaphragm for the driver, or having the woofer reconed, people would often toss the original units altogether and install a replacement of different type. The manufacturers and models used here are all over the place. Sometimes, people would even use replacements with a wrong impedance (e.g. 8 Ohms), resulting in a mismatch to both crossover and amp, diminishing overall sound quality. As for some replacement horn drivers, people would use certain tweaks to balance the sound. E.g. with some overly bright drivers, a ball of cotton wool would be inserted into the driver's throat to tame excess highs; to reduce the overall level, a resistive pad (e.g. 16 Ohms in parallel with the driver), sometimes even with an inductor in series (e.g. 1mH) would be used.

Many people, including myself, say that a Jensen V21 is essential for a real classic tube Leslie sound, since most other drivers are more or less brighter, and also louder. In terms of blending with the woofer, V21 just seems to be the best match. As for woofers themselves, the P15LL is mostly favoured over the (also classic) C15L, due to better balance in the low end, and also a nice "crunch" in the bass/low mids when being run hot.

The following list contains all the different types I just hinted at, to the best of my knowledge - restricted to those of correct impedance (16 Ohms).


HORN DRIVERS

Vintage Original
Jensen V21
Replacements
Raytheon V21
Jensen/Rola V21
Atlas PD-5VH / PD5VT
Klipsch K-55-V / K-55-X
Atlas PD-60 (60W)
JBL 2482 (120W)
P-Audio PDA-50
University ID 30/40/60
Electro-Voice 1823M
Altec 291-16A
Adastra DU60/70/100
Eminence PSD 2002
Peavey RX-22
RCF TW-100 / TW-101
Monacor KU-316 / 516
Fane HF 100
Used In Current Models
Atlas OEM
Eden Electronics OEM

WOOFERS

Vintage Original
Jensen P15LL
Jensen C15L
Rola C15L
Utah
Replacements
Eminence Delta 15b
Jensen P15N
Jensen C15K / N
Weber 15A200
JBL 140/145
Mackie SR1530Z
Fane KP-15 100C
Used In Current Models
Eminence OEM



35W,sometimes with bell labeled "Hypex"

visually identical to the original Jensen unit
later model used in some transistor Leslies
40W, said to be closest to the V21 freq. response
made by Atlas for Klipsch, identical to PD-5VH
60W, used in Leslie 860, said to sound better w/o bell
120W, used in Leslie 925 (very loud, so use w/ pad)
50W
30/40/60W


60/75/100W, also marketed under other brand names
100W

100W



100W, modeled after PD-60, used by Hammond
100W, Ferrofluid, offered by 3rd party dealers




35W, used until 1965
40W+?, used from 1966 to 1971
40W+?, used from 1972 onwards
Alnico or ceramic magnet, used from 60's to 70's

400W, standard replacement, OEM version also fitted in current Leslies
50W
100W / 50W
40W, engineered towards a Jensen P15LL replication

made by Eminence


400W, exact or slightly modified version of 15b