Alnico magnet, 8 ohm impedance, around 15 watts handling, hammertone/"oyster" coloured frames, supplied to Jennings by Celestion in the last third half of 1960 and in early 1961. One also finds, in parallel, early T530s (forerunners of the Celestion blue), pretty much identical to the CT3757 in terms of appearance and general characteristics. Quite why the two models should have overlapped in such a way is not clear. According to the Celestion log book, the T530 is cast as a sort of derivative of the CT3757: "T530 - G12 - As CT3757. Sprayed Oyster.", "G12" being the generic type. Perhaps so. As it stands however, the earliest known surviving T530 (early June 1960) is a good deal earlier the earliest known CT3757s.

As for purpose, the CT3757 / T530 was commissioned by JMI for its new third circuit AC15s. Later on, use was extended - occasionally - to AC30/4s (TV Fronts and split fronts). See the section towards the end of this page.

So far as one can tell, the T530 / CT3757 was the first type of speaker to have been provided with a "VOX" label by JMI.

An early T530 - dated 7th June, 1960 - in a two-tone AC15 (third circuit) with no serial number.

Where early T530s are concerned, labels appear (operative word) to have been glued on in such a way as to present "VOX" horizontally in the cabinet. By contrast, labels on CT3757s are normally aligned with the speaker terminals and seem to have been applied prior to the fitting of the speaker in the amplifier. For the orientation to serve as a means of identifying the type of speaker in view requires more examples, however. The labels on two T530s with June 1960 date codes look unusually clean. Are they repros? Compare the one illustrated above with any of those illustrated below. It is probably well to note too that by late 1960 all labels were fixed such that "VOX" appeared horizontally, so there is only a brief "window" for the potential identification of models in this way (if at all).

Early T530s: "07FE" and "21FE" = 7th and 21st June 1960, respectively. Later instances from 1960 survive too.

CT3757s: "26HE" (two instances); "08JE"; "20JE" (two instances); "23JE"; "26JE"; "30JE" = 26th August 1960; and 8th, 20th, 23rd, 26th, and 30th September.

One of the latest AC15s to have been fitted from factory with an early T530 or CT3757 (probably the latter) is serial number 4408, mid 1961. Blues had already been used in a number of earlier amps.

Some examples

Date code "08JE" = 8th September 1960. The first of the two speakers above.

Date code "26HE" = 26th August 1960. The second of the two speakers above.

Cone code "RIC 1 EI" - speaker dated "26HE". The page on "RIC" cones in Celestions can be found here.

Below a CT3757 from December 1962, fitted as a replacement in a two-tone AC15 from early 1960. No "Vox" label is present.

Date code is "16LG" = 16th November 1962. The cone code is RIC 1 DO.

AC30s with CT3757s

Below, an AC30/4 chassis and what may have been its original speakers, either Celestion CT3757s or just possibly very early T530s, in a later AC30 cabinet (from 1963). Note the early form pink and yellow wiring. Labels are oriented with the speaker terminals.

The cabinet has rounded corners at back. Celestion CT3757s and T530s were effectively the same speaker.

As mentioned on the updates page in September, several other AC30/4s are known with such speakers. A pair also turned up some years ago in a Vox UL460 cab (as replacements for its originals). It seems highly unlikely that the five pairs in view were simply ransacked from single-speaker AC15s, the only model of Jennings amplifier fitted with this type of Celestion as standard, or at least moderately standard (serial numbers in the 4100s and 4200s).

Vox UL460 speaker cabinet with a pair of CT3757s, added in the 1980s, date codes late August and September 1960 (illustrated in the section above). The original speakers - Celestion T1225s - were long gone.

That certain AC30/4s (both TV Front and split-front) should also have been issued with 3757s (from factory) in late 1960 and early 1961 seems perfectly in order. Date codes are normally in the last third of 1960.

As for organs: speakers were hidden from view and, so far as we know (from photos and report), did not have special labels. Besides, the various ranges at this time were marketed not as "Vox" but "Jennings". The first "Vox" organ was the Continental.

In spite of what is sometimes asserted, JMI rarely used one type of speaker invariably for a particular model of amplifier then moved invariably to another in the late 1950s and first years of the 1960s. Nothing quite so abrupt or simplistic. Consistency only really came in during the course of 1961. For the time being, the charting of occurrences of types is key. As for Celestion 3757s in AC30/6s ...

Below, recently sold in the USA, an AC30/4 chassis in a new cabinet, serial number plate from a later amp, and a pair of CT3757s (less likely early T530s). Whether these last belonged originally to the same AC30 as the chassis is not known for certain, but there is a strong possibility that they did.

Distinctive wear along the front edge, in particular at left. One of the Hunts caps in the preamp has the date code "IAY" = 39th week 1960 for its manufacture.

Serial number plate from some later amp.

Shiny screws, nuts and washers throughout the cabinet. Non-original wiring of the speakers.