5th December

Thanks to David, pictures of late JMI Supreme serial number 1304 with a Supreme cab originally isued with a different amp.

Late JMI Supreme serial number 1304. Cab and amp both re-grilled, speakers in the latter refitted.

30th November

A note on the resistor arrays in single-speaker Super Foundation Bass cabinets (following a recent question). Their purpose was to reduce the drive of the amplifier - effectively load its output down - in order to protect the Goodmans speaker.

The resistors, four in total, 20 ohms apiece, and wired in parallel, were part of the positive line from the input socket to the speaker's terminal. The common (negative) line ran directly from the input socket to the speaker.

Wiring the resistors in parallel gave a total resistance of 5 ohms - that in addition to the 15 ohm impedance of the Goodmans. Safe to say the maths is complex. Resistance is for the most part static, impedance dynamic - but the result was to create a small "power soak" such that the speaker would be safe.

The resistors were 9 watt wirewound ceramics bought in from Welwyn, their notional power handling in total being around 36 watts. The reason for the resistor array? When new, Super Foundation Bass amplifiers were capable of putting out well over 100 watts, power exceeding the recommended rating of all Goodmans 18" drivers: the Audiom 91 "Standard" rated at 50 watts, the Audiom 91 "Bass" at around 80 watts; and the Audiom 91/100 at a full 100 watts. In most instances a cabinet with a closed back will have allowed the speaker to handle 10-20 watts more, but it may be that Goodmans had already factored that in.

At any rate, JMI felt that the single speaker on its own was not enough to cope with the amplifier. The resistors provided a margin of safety. In late 1967, when the twin-speaker Super Foundation Bass cab was introduced, no such array was required. Two 18" Goodmans could easily cope with the amplifier's output.

A detail from a single-speaker Super Foundation Bass cabinet. On the tag board underneath the speaker (the picture has been inverted for convenience), four 20 ohm Welwyn 9 watt wirewound ceramic resistors, wired in parallel for a total of 5 ohms.

13th November

The list of Celestion speakers used by Vox, 1967-1973, given below (7th November) has now been moved to a page of its own - available here. A number of the entries have been expanded.

It is perhaps worth noting that one printed source states that Celestion T1304s were used in JMI Defiant speaker cabinets. No further point of reference is given though. In fact, most JMI Defiants had T1279s (G12H - heavy magnet). T1304s by contrast had medium magnets and are likely to have been the poly grey speakers without labels fitted in Vox Gyrotone cabinets. Perhaps a small number made their way into Defiants, but without referenced examples it is impossible to know. No T1304 seems to have come up on the open market. T1279s from Defiant cabinets do surface from time to time however.

8th November (2)

Just to add to the list of Celestion speakers used by "Vox Sound Limited" (entry for 7th Nov.), a pair of T1364 Greenbacks in a Defiant speaker cabinet. The orientation of the terminals and labels and nature of the wiring indicates however that this was not their original application. Also to say, in another photo the original Goodmans purchase order sticker can be seen stuck to the baffle.

8th November

Below, a couple of details of an early "Vox Sound Equipment Limited" Multi-Link 1 speaker cabinet (4x12", 15ohm impedance) - probably mid 1969. The original drivers have been replaced, but still present the impedance transformer, wiring harness, and printed input jack wiring schema.

On the right-hand side of the schema, the jacks one above the other, the two wires from the upper one leading up to the speakers. At left, the terminal block and transformer.

The wiring is arranged such that an amplifier plugged into either of the two sockets would (1) drive the speakers and (2) any other speaker cabinet plugged into the second socket ("daisy chained").

It is not clear at present exactly what effect the transformer would have had on the overall impedance of the Multi-Link 4x12" and a second - perhaps mis-matched - cabinet. More to follow.

The serial number on the plate is unfortunately not readable definitively, but it looks like "00x" - possibly "004".

7th November

13th November: the list of Celestion speakers used by Vox, 1967-1973, has now been moved to a page of its own - available here. A number of the entries have been expanded.

Some provisional material on Celestion speakers in Vox solid state amplifiers. Remember that these amplifiers, across the range, required speaker cabinets with a total impedance of 15/16 ohms.

For the time being, speakers fitted to organs and organ speaker arrays will be left out of account. For an overview of Celestion "T" numbers, see Brian Harding's excellent list here.

Some of the speakers listed below are unlikely to have been made in large quantities.

"Jennings Musical Industries" (Spring 1967 to early 1968)

CT7721 and CT7442: 10 inch, ceramic magnets, 10-15 watts handling, 15ohm. NIB4 cones. Used in Vox Traveller combos; single 10" speaker enclosures for wall mounting; and possibly in some Line Source 40 column units.

CT7724 : 10 inch, ceramic magnets, 10-15 watts handling, 8ohm. NIB4 cones. Used in pairs, wired in series, in Vox Virtuoso combos.

T1088: G12, alnico magnet, 17-20 watts handling (JMI reckoned on 17 watts), 8ohm. Sprayed poly grey. Used in pairs, wired in series, in Vox Conqueror speaker cabinets. There is no evidence to suggest that JMI fitted Conquerors with anything other than these speakers.

T1109: G15C, ceramic magnet, 50 watts, 15ohm. Poly grey. Used in Vox Dynamic Bass speaker cabinets.

T1225: G12H, ceramic, 25-30 watts, 15 ohms. Poly grey. In 1967 some were issued with green rather than poly grey dust-covers. Used in Vox Supreme cabinets and perhaps certain Line Source 60 public address speaker columns.

T1252: G12L (sometimes called G12S), lightweight magnet, 12/15ohm. Poly grey. Used in certain Line Source 60 public address columns, one set with date codes *19KL" = 19th October 1966. A set of four of much the same date was removed from a LS60 some years ago and transplanted into a 4x12 Multi-Link 1 cabinet from 1970. At present, there is no evidence to suggest that T1252s were originally used for anything other than Line Source 60 columns.

T1279: G12H, ceramic, 25-30 watts, 8 ohms. Pairs wired in series for a total impedance of 15/16 ohms in Vox Defiant speaker cabinets.

T1279 (15ohm): two sources record instances of 15ohm versions of the T1279. If correct, these are likely to have been implemented in the same way as T1225s.

T1296: G18C, ceramic, 100 watts handling, 15ohm. Poly grey. Used in Foundation Bass speaker cabinets.

T1304: G12M, ceramic, 8ohm. Poly grey. No example has yet come to light, but these may be the speakers without labels in Gyrotone 2 and 3 rotating speaker enclosures.

T1360: Exponential horn, 20 watts handling, 15ohms. Sets with July 1967 date codes appear in certain Supreme speaker cabinets.

T1463: Exponential horn, 20 watts handling, 3ohms. Prototype horn unit containing five T1463s dated May to August 1967. Total impedance of the unit: 15 ohms.

"Vox Sound Equipment Limited" (mid 1968 to late 1969)

VSEL came into being in the summer of 1968, taking over a good deal of unsold and incomplete stock from what had been JMI - JMI ceased trading at the end of April 1968. VSEL put its own serial number plates and speaker labels on new and existing items. The company bought in very few Celestion speakers however, its preferred supplier being Goodmans.

T1088: alnico G12, 8ohm. Vox AC30s and wall-mounted speaker units (each containing a single 12" T1088).

T1096: alnico G12, 15ohm. A set with date codes "10JA" = 10th September 1968 occurs in a Supreme speaker cabinet. But this cabinet and a similar one with a "Vox Sound Limited" serial number plate may have been made up of surplus parts.

"Vox Sound Limited" (1970 into 1973)

Following VSEL's collapse in December 1969, VSL was brought into being (in January 1970) to take the Vox name forward. VSL took over a good deal of unsold and incomplete stock from its predecessor, just as VSEL had from JMI.

VSL's preferred supplier was also Goodmans, but various batches of Celestions were bought in, perhaps at times when Goodmans was overstretched. VSL did not have its own speaker labels printed up, using VSEL's instead.

T1088: Still used for runs of AC30s, 1970 into 1972.

T1096: G12, alnico magnet, 15ohm. Used in 1972 for AC30s. A set of four T1096s, one with date code AF10 = 10th January 1973, occurs in a Vox Supreme cabinet with a VSL serial number. But the cab (and one with earlier 1096s noted above) may have been made up of surplus parts after VSL had come to an end.

T1102: G15C Greenback, ceramic, 50 watts, 15ohm. A pair of T1102s with VSEL labels used in a 2x12/2x15 Multi-Link 2 speaker cabinet. Date codes unknown.

T1217: G12H Greenback, ceramic magnet, 15ohm. Used in Vox Supreme speaker cabinets, and 2x12/2x15 Multi-Link 2 cabs. Date codes June 1970, February 1971, and September 1971.

T1252: G12L Greenback, 12/15ohm. Also used by JMI (see above) but poly grey finish. Date codes July 1969 and June 1970.

*T1364: G12H Greenback, ceramic, 8ohm. A pair in a Defiant cabinet, but this is unlikely to have been their original home.

T1925: G12M Greenback, ceramic magnet, whizzer cone (tweeter), 15ohm. Used in 4x12 Vox Supreme and Vox Companion cabinets. Date codes June, July and August 1972. A couple of sets have "EF" which is probably an error for "FE". The cabinets in which they occur have inspection (completion) tags dated 11th July 1972.

T2056: G12, alnico magnet, 17-20 watts handling, 8ohm. Used in 1972 for AC30s.

6th November (2)

Just to add that pairs of Goodmans 8ohm speakers (type 241/1214/8) wired in series were used in Vox Gyrotone 2 and 3 enclosures as well as in Vox Defiant speaker cabs.

6th November

Before moving on to Celestion speakers, a final note on Goodmans - IMPEDANCE. "Vox Sound Equipment Limited" Conqueror and Defiant cabs had two 8ohm drivers wired in series for a total impedance of 15/16 ohms. Supremes used four 15/16ohm drivers wired in series/parallel also for a total of 15/16 ohms. 15/16 ohms was the impedance required by Vox amplifiers across the solid state range.

As mentioned yesterday, the various types of speaker with "241" frames produced by Goodmans in the late 1960s and early 1970s are often difficult to tell apart. There are however the stickers indicating impedance.

A detail of one of the Goodmans 241s in the speaker cabinet accompanying Vox Defiant serial number 2494.

In the absence for the time being of a good photo of a "241" in a Supreme cab, a couple from a Multi-Link 1. The full type is: 241/1214/15.

Impedance 15 ohms.

Goodmans cone code "1214".

5th November (2)

It is likely that the blue hammerite speakers mentioned in yesterday's entry were originally made by Goodmans for Selmer but for whatever reason sent out to Vox instead.

One of the two Goodmans drivers in the speaker cabinet of a Selmer Thunderbird 50 Mark II combo from early 1968.

5th November

Further notes on Goodmans speakers. First, a speaker that is almost identical externally to the one illustrated at the foot of yesterday's entry but of a different Goodmans "type": 241/1235/12.

Given the impedance of 12 ohms, this speaker was probably produced for WEM. The difference between a "1235" cone and a "1205" is not known for certain at present, but it may be that the former is lighter.

Type 241/1235/12, probably for WEM

Second, 18" Goodmans speakers for Vox solid state amplifiers. In late 1967 / early 1968 Goodmans designed a new type of Audiom 91 for JMI - 15/16ohm, cone 1803/78173, type 95062. These were used in Foundation Bass and single-speaker Super Foundation Bass cabinets. Some were sold in late 1968 / early 1969 by "Vox Sound Equipment Limited", which put its new-style serial number plate on the back panels of the cabs concerned.

A Goodmans 95062 in a Foundation Bass speaker cabinet sold by "Vox Sound Equipment Limited", the cab's serial number unusually not stamped with a number.

In early 1969, Goodmans provided VSEL with a new 15/16ohm 18" driver - type 93170, but with the same cone as the 95062. Standard VSEL labels were affixed to the dust-covers.

For twin-speaker Super Foundation Bass cabinets, VSEL contracted Goodmans to produce an 8ohm 18" driver - type 03CiF / H17 and H28. Two were wired in parallel for a total of 15/16 ohms.

In at least one "Vox Sound Limited" Super Foundation Bass speaker cabinet, however, two 15/16ohm drivers are wired up in series for a total impedance of 8ohms (SFB amplifier sections required 15/16). But it is not clear what type of amplifier the cab was intended for, or whether the resulting impedance was simply an old-fashioned error.

4th November

A note on Goodmans speakers in Vox Supreme speaker cabinets. Goodmans normally described its speakers in three ways: (1) by a model or range name; (2) a code for "type" on a paper slip stuck to the speaker's label; and (3) a purchase order number (in case a replacement was needed) also on a paper sticker.

The speakers used in Supreme cabinets (and some Multi-Link speaker cabinets) are part of the Audiom range. "Type" was a three-fold designation: code number for frame / code number for cone / impedance - for example 241/1205/15. "241" is a heavy-duty frame, "1205" a type of 12 inch cone, and the impedance obvious. As Jennings / Vox generally removed any labels that had been affixed to the dust-covers by suppliers, stickers designating "type" are lacking - or at least none has come to light so far. But a few survive on identical speakers supplied to other amplifier manufacturers.

On the other hand, purchase order numbers, glued onto the frame beside the solder terminals, have survived better. The form of words on the sticker is normally: "For replacements quote P/O" - then the number. These P/O numbers were presumably recorded by Goodmans in its log-books along with the name of purchaser, size of order, and number of items purchased.

From late 1967 / early 1968 through to 1972 Goodmans supplied Vox with three different types of "241" (heavy-duty) speaker, all with an impedance of 15/16 ohms, here called "A", "B" and "C" simply for convenience.

An overview of Supreme speaker cabinets, to be updated in the coming days, can be found here.

A) - from late 1967 / early 1968 through to mid to late 1969. Black plastic dust-cover initially with smooth outer rim. The rims of later batches had diagonal striations. Early and later versions both have a sort of spider's web pattern in the sunken roundel; and at centre, an oculus.

One of the speakers from the cabinet accompanying JMI Supreme amplifier section serial number 1094. JMI did not number its speaker cabinets. Smooth dust-cover rim.

One of the speakers of "Vox Sound Equipment Limited" Supreme speaker cabinet serial number 212, issued from factory with Supreme amplifier section 2231. Dust-cover rim with diagonal striations.

B) - between late 1969 and early 1971, occasionally a species of "241" with a hammerite blue frame. Drivers of this type were fitted in Supreme cabinet serial number 272. The accompanying amplifier will have had a number in the low 2300s.

1969 certainly, possibly the 40th week, though it is not clear how the "6" should be read.

C) - from mid 1971 into 1972. Still a black dust-cover, but now quadrants of "furrows" radiating from the outer edge, and a square panel at centre. The square panel normally had the green Goodmans label.

"Vox Sound Limited" Supreme speaker cabinet serial number 474.

Below, an example of the same type of speaker, not from a Vox amp, with its Goodmans label - and sticker designating "type" - in place.

The sticker reads: "241/1205/15".

3rd November

Thanks to Rene, pictures of "Vox Sound Limited" Supreme, serial number 2355,. with tilt-back stand. The speakers are Celestion G12H T1217s, the latest date code "BD2" = 2nd February 1971.

VSL Supreme, serial number 2355. The speaker cabinet is serial number 300.

The page on Vox Supreme speaker cabinets will be updated shortly.

2nd November

Thanks to Ray, pictures of a "Vox Sound Limited" Supreme, originally with tilt-back stand, bought from Dawsons in Warrington around 1971. Speakers are heavy-duty Goodmans.

Speaker cabinet serial number 474. Number 525 has Celestion speakers dated July 1972.

June 1972, advert placed in the music press by Dawsons, which is still in business today, probably in conjunction with Vox.

From left to right: Focus folding PA speakers; a PA100SS on top of a set of organ speakers; SG200 bass and SG200 guitar; two "Hastings" pedals (a wah and a wow-fuzz?); a discotape unit; AC30 with an unidentifiable item on top; and a Supreme in tilt-back stand.

1st November

Thanks to Heinz, pictures of a pristine "Vox Sound Limited" Multi-Link 2 speaker cabinet, 2x15" and 2x12". The 12" drivers are Celestion G12H T1217s, date codes 10th September 1970. The 15" drivers are Goodmans Audiom 81s.

Pictured with an AC50.

Complete with speaker impedance matching unit and serial number plate (serial number 95).