B120

• 1.1:  B120 Exterior Chassis Top Rear View
• 1.2:  B120 Rear View 
• 1.3:  B120 Rear Exterior Chassis View
• 1.4:  B120 Front Interior Chassis View
• 1.5:   B120 Rear Interior Chassis View
• 2.1:  B120 Front View
• 2.2:  B120 Rear View
• 2.3:  B120 Front Exterior Chassis View
• 2.4:  B120 Top Exterior Chassis View
• 2.5:  B120 Serial Number Label

L120 (External Link)

L120

• 1.1:  L120 Front View
• 1.2:  L120 Front Exterior Chassis View
• 1.3:  L120 Rear View
• 1.4:  L120 Interior Chassis View
• 2.1:  L120 Front View
• 2.2:  L120 Rear View
• 2.3:  L120 Front Exterior Chassis View
• 2.4:  L120 Rear Exterior Chassis View
• 2.5:  L120 Interior Chassis View
• 2.6:  L120 Serial Number Label
• 3:  L/B120 with Centered Reverse Logo

120 Energizer Slave Unit

• 1.1:  120 Energiser Slave Unit Front View
• 1.2:  120 Energiser Slave Unit External Rear View
• 1.3:  120 Energiser Slave Unit Internal Rear View

120 PA

• 1:  120 PA Front View
• 2.1:  120 PA Front View
• 2.2:  120 PA Rear View
• 2.3:  120 PA External Chassis Top View
• 2.4:  120 PA Interior Chassis View

120 R

• 1.1:  120 R Front View
• 1.2:  120 R Rear View

1.1: Sound City B120 Exterior Chassis Top Rear View
~120 watts from six EL34s. The following is according to this amp's owner: "Had a bad OT so I used a Marshall replacement and removed two EL34s. Replaced all filter caps. Replaced all internal caps with "orange drops." Replaced all those nasty red resistors with metal film resistors. Preamp tubes are Sovtek 12AX7LPS (not my first choice, but what I could find at the time). Phase-inverter (PI) tube is Groove Tubes USA 12AT7. Output tubes are Svetlana EL34s (now SED). At some point I want to replace the active [Mark 4] preamp with something else but haven't decided what yet."   Photos Home Page

1.2: Sound City B120 Rear View   Photos Home Page

1.3: Sound City B120 Rear Exterior Chassis View
Note the Dallas Music Industries (DMI) rear panel label.    Photos Home Page

1.4: Sound City B120 Front Interior Chassis View   Photos Home Page

1.5: Sound City B120 Rear Interior Chassis View   Photos Home Page

2.1: Sound City B120 Front View
~120 watts from six EL34s, very early DMI-era Mark 4 (IV) bass model, black "basketweave" Tolex, original black-capped knobs, silver vein, gold trim. Head is sitting atop a DMI-era F215 bass cabinet. (For photos of this rare, Mahwah, NJ bass cabinet, see Photo Page 11.)   Photos Home Page

2.2: Sound City B120 Rear View   Photos Home Page

2.3: Sound City B120 Front Exterior Chassis View
Note the positions of the five preamp tubes relative to the L120 model.   Photos Home Page

2.4: Sound City B120 Top Exterior Chassis View   Photos Home Page

2.5: Sound City B120 Serial Number Label
Note that this Dallas Music Industries (DMI) label has been glued over a Dallas Arbiter label, which provides additional evidence that for a time DMI-era heads were built in the UK but shipped to the US for DMI "relabeling." (c1973/1974).   Photos Home Page

1.1: Sound City L120 Front View
~120 watts from six JJ EL34s, heavily modified/rebuilt L120 Mark 4 (IV), black "basketweave" Tolex, non-original "chickenhead" knobs, silver vein, gold trim, grommet over headphone output, replica logo. Although this amp started life as a Mark 4, it was a non-working hulk with only some caps and both transformers and was almost completely rewired.   Photos Home Page

(This amp is the property of this site's author.)

1.2: Sound City L120 Front Exterior Chassis View
As part of the amp's preamp mod, only three (of five) 12AX7s remain (JJs), and a 4-Henry Hammond choke was added as a part of the amp's noise-reduction mod.   Photos Home Page

1.4: Sound City L120 Interior Chassis View
95% of chassis wiring was redone and 95% of components are new, except for original Partridge transformers and a few small odds and ends. Passive preamp mod was based on Hoffman Amps' "Plexi 100" mod. Output rewire was based on standard 120 Mark 4 schematic.   Photos Home Page

2.1: Sound City L120 Front View
~120 watts from (up to) six EL34s, Mark 4 (IV). Aside from some surface dirt and dust, this is a fine example of an almost 100% stock Sound City L120 Mark 4.   Photos Home Page

2.4: Sound City L120 Chassis Exterior Rear View
Only four of six EL34s being used.   Photos Home Page

3: Sound City L/B120 with Centered Reverse Logo
I have no data that indicates the logo on this L/B120 was ever a standard logo offered on Sound City amps; however, it's been suggested this logo was used on a tape echo machine manufactured/offered by Sound City at some point. Note also that the logo appears to be a sticker or decal, rather than a screwed-on plate like other, more common Sound City logo designs. That said, it's a very clean example of a Sound City 120, and who knows, the logo could have been one used on other pieces of Sound City gear.   Photos Home Page

1.1: Sound City 120 Energiser Slave Unit Front View
~120 watts from six EL34s. This seldom-seen Sound City amp was exemplary of a trend seen primarily during the 70s: extension (or "slave") power amps without preamp tone controls. The idea behind these "slaves" was to provide a less expensive way to add power for an extension speaker cabinet (or cabinets) by using the Slave output of some "master" Sound City head. These Slave outputs came after the "master" amp's preamp, so the "slave" unit was driven by the "master" preamp. The entire "master/slave" concept used by Sound City, Hiwatt, SUNN, and other 70s-era manufacturers, eventually fell by the wayside due, perhaps, to the politically incorrect nature of the nomenclature.   Photos Home Page

1.2: Sound City 120 Energiser Slave Unit External Rear View
Note that this model's rear panel view is the reverse of a standard L/B120 head: the power selector switch is on the right and the impedance selector switch and speaker outputs are on the left.

Another thing to consider about this model is the notion held by many that, sonically speaking, the Mark 4 active preamp is perhaps less than desirable. Would this amp provide the ideal solution? A Sound City 120's output section, which no seems to denegrate, but without the Mark 4 preamp's problems, to which many seem to point.   Photos Home Page

1.3: Sound City 120 Energiser Slave Unit Internal Rear View
Note the orientation of the six EL34s, which are positioned in two groups of three and which is a departure from the standard 120 head's six EL34s in line. This model seems to represent a unique chassis type; no other Dallas Arbiter-era Sound City amp used this chassis (although the DMI-era Sound City SMF head did have its eight EL34s in two groups of four). Also note the orientation of the output transformer (left) and the power transformer (right). These transformers are not only in the reverse position from a standard 120 head, but they are turned/oriented 90 degress with respect to one another, which is seen in only two other Sound City amps: the Bass 150 and the ST 50 PA Mark 3.   Photos Home Page

2.3: Sound City 120 PA Exterior Chassis Top View
Note the black tube cover in the lower left-hand corner. This extra tube is a "6C4 (1/2 ECC82)," which, according to this amp's owner, is a "cathode follower" that "allows the use of the 'reverb out' socket to drive other gear and long cables without high-frequency loss."    Photos Main Page

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