Jennings Musical Industries (JMI) 1967-1968

The caption reads: "A 50 watt peak power bass amplifier with a bass tone as rich and deept as a newly tapped oil well, and yet with fantastic tonal variation (exclusive TONE-X gives you this). The separate frequency-tuned speaker cabinet houses a special 15 in. loudspeaker. Four inputs through two channels. Supplied with roll-away stand. Dimensions:

Amp. Section - 23 3/4 in. x 9 1/2 i.n x 9 1/2 in.

Speaker Section - 24 in. x 25 in. x 15 in.

In actual fact the output of the Dynamic Bass by conventional measurement (rather than peak power) is more like 30W. The amp had two channels - normal and bass, the normal channel with distortion (operated by a footswitch) and mid-range boost (MRB); and the bass channel Tone-X, a sweep tone control. Speaker cabinets were normally provided at first with a Celestion T1109 driver, later a Goodmans unit.

The analogue of the Dynamic Bass in the solid state guitar amp range was the Conqueror, which had the same 30W power section, but a different preamp.

The Dynamic Bass, however, was not produced in such great numbers as the Conqueror. It is worth noting too that the Dynamic Bass and Conqueror amp sections were slightly smaller than the other amps in the range (Foundation and Super Foundation Bass; Defiant and Supreme).

The price list of April 1967. The Dynamic Bass cost £149 and 2 shillings, in today's money, around £2,500. To give some context, the list sets the AC30 almost on a par at £143.

In terms of general characteristics (and changes):

Below, a growing register of surviving amps. If anyone knows of any early Dynamic Basses that have not yet been included, .

Serial number 1011 - currently in Italy

An added DIN plug socket on the left hand side of the control panel fascia, but otherwise unchanged and original. Even the T-screws survive (to fix the amp the chrome frame). Both amp and cab have simple VOX logos in silver. Thanks to Sergio for the pictures.

Serial number 1029 - currently in the UK

In good order externally. Control panel brown; one of the pilot lights renewed.

Serial number 1035 - currently in Germany

Serial number 1048 - currently in the UK

Thanks to Paul Johnson for the info.

Serial number 1063 - currently in the UK

Supplied by Cooke's "Everything Musical" of Peterborough. The cloth has browned like that of certain early Foundation Bass sets. Good to see the Belling Lee mains input socket still in place.

Serial number 1066 - currently in Switzerland

Thanks to Uwe for details of the amp's existence.

Serial number 1068 - currently in Australia

The inside of the amp cabinet has, in chalk, "May '67". "May" is all probability the lady who did the grille cloth - her name is often to be found chalked in 7-series speaker cabinets and in some solid state amp cabs. It is likely in this case May was also the month in which she fitted the cloth - and so the added year numerals.

Serial number 1087 - currently in Germany


Serial number 1089 - currently in the UK (?)

Serial number 1121 - currently in Belgium

Great condition. Thanks to Jullian for the pictures.

Serial number 1122 - currently in Europe

What looks to be a "Vox Sound Limited" (rather than JMI) Dynamic Bass set, but with a JMI serial number plate on the amplifier section, and VSL plate on the cab (sn. 186).

Serial number 1135 - currently in the UK

In great condition and with its original cover. Only a few new caps in the preamp. For further pictures, click on the button below.

Serial number unknown - currently in the UK

Sold on ebay.uk in the 2000s. Probably a very early one. Note the blackness of the control panel.

Serial number unknown - currently in the UK

A nice amp - as above, probably an early one. Black control panel.

Serial number unknown - currently in France

A complete set. Apparently a black control panel.

Serial number unknown - currently in Europe - Slovenia or Czech Republic

Brown control panel, preamp fixings on top of box, white ceramic rings round jack input sockets.

Serial number unknown

A good looking amp. Brown control panel, and cloth faded to brown too.

Late 1967 / early 1968

"Solid State" now in the logo. Black plastic input sockets.

At this point too the preamp fixings on top of the box disappear

Serial number 1154 - currently in Europe

"Solid State" in the logos of both amp and speaker cabinet.

Serial number 1177 - currently in the USA

Serial number 1187 - currently in the UK

Replaced grille cloth front and back, otherwise in good condition. Pictures of the preamp show that one of the red filter caps has the date code "G7" - August 1967 - giving a useful point of reference.

Serial number 1198 - currently in the UK

Thanks to Steve for the pictures.

Serial number 1241 - currently in the USA

Still "Vox Amplifier" on the serial number plate. Formerly owned by Reisz Promotions in Germany. The entire collection at Reisz Promotions (which was large) was bought by Music Center and shipped to the USA in the late 2000s.


Serial number 1248 - currently in Europe

A set complete with chrome stand for the amplifier section. The serial number plate still has "VOX AMPLIFIER" at its head.

Serial number unknown - currently in the UK?

Serial number unknown - currently in Germany?

A nice full rig sold on ebay.de some time ago.

Serial number unknown - currently in Europe?

"Solid State" in the logo of both cab and amp.


"AMPLIFIER" alone on the serial number plate

Serial number unknown - currently in Europe

Advertised on vintageandrare a little while ago. Control knobs replaced, but otherwise a nice example. Probably one of the last JMI units made.

On to the next page of Dynamic Basses - .