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JPS Esprit Conundrums - Sound System

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Car hifi has come a long way since 1979. There are options for replacing the sound system in a JPS Esprit with a modern digital set-up. But suppose you want to restore the 1970s sound experience. Puzzles and potential pitfalls lie ahead.

I remember Paul at UK Sportscars keeping me away from the radio cassette on my test drive of JPS #40 last September, “Who needs music when you can listen to the 907?”

I subsequently brought along one of my favourite 1980s cassettes for the first drive home. Sadly, my nostalgia moment ended with a few burps from the loudspeakers, a squeak from the radio, and a mechanism jam with the cassette tape swallowed up. No problem, I thought, it should be a straightforward matter to fix the sound system later. I enjoyed the Dellortos singing on the way home.

According to the Lotus Spare Parts List, the JPS Esprit was originally fitted with a Hitachi Digital radio cassette, connected via a crossover unit to two mid-range/tweeter door mounted speakers and to a single bass speaker under the dashboard. The radio cassette in the JPS Esprit differed from the Motorola LT 558 fitted to a regular S2 (see @GTK’s Lotus Motorola Radio Cassette - The Complete Reference). The addition of the bass speaker and crossover unit was presumably intended to deepen the sound. Predictably, none of the spare parts listed seems available from the usual sources.

The PO had taken good care of the interior trim in #40, and both original door speaker grilles remained in place (see photo). However, not much else was left of the specified sound system: the radio cassette was a Sharp RG-5850, the two door speakers were tired aftermarket additions, there was no sound from the oval bass speaker (see photos), and the crossover unit was nowhere to be found.

The first restoration conundrum was the radio cassette. A little research on the Forum (h/t @LOTUSMAN33) identified that Hitachi Digital 1 players are as rare as gold dust. The closest that a search on eBay came was a 1978 magazine advert for one!

The Sharp RG-5850 dates from around 1980, according to Radio Museum, and was considered a high specification unit at that time. So might repair represent a period friendly alternative? Very helpfully, Mike at Chrome London recommended Steve Smith at Revive Car Audio, and Steve in turn managed to restore the Sharp to functioning condition (with the added bonus of an auxiliary line input).

The second conundrum was the two door speakers. The original fixing rings behind the grilles say “Quality SEAS Speaker” and “Made in Scandinavia”, and have a 93 mm diameter between the fixing holes (see photo). I have seen these described misleadingly as 4 inch speakers. They are in fact closer to 3 1/2 inch, with the consequence that it is impossible to fit standard 4 inch speakers without either (a) drilling new mounting holes into the door trim, and replacing the original grilles and fixing rings, or (b) drilling extra screw tapping holes into the speaker rims, while trying not to damage the cones. The PO had opted for the latter route and #40 came with a pair of hacked and tired 4 inch Pioneer TS-G1001i speakers.

So far, trying to track down a pair of mid/upper range speakers that have 93 mm fixing holes has proven fruitless. Neither Lotus nor SEAS have been able to provide any information about the original speakers or potential replacements. The only refurbishment route for the Pioneers seems to be to replace them with similar 4 inch speakers and to use the SEAS fixing rings as a template for drilling into the speakers, just as the PO appears to have done. Ouch!

The third conundrum was the crossover unit. Steve at SJS informed me that, “the crossover unit is blue and attached to the back or side of the glove box.” However, there was no sign of one in #40. It seems that the PO cleared out a lot of wiring ten years ago when fitting new door speakers. The result was that the leads from the oval bass speaker simply disappear into the loom, never to reemerge, and the silence of the bass speaker was plausibly explained by the missing crossover.

So, how to replace the “crossover”? Approaching regular car audio suppliers was unhelpful: no one made or sold car audio systems with a similar configuration to the JPS Esprit, and no one had heard of a “crossover unit” which fed a single shared bass speaker.

Absent any detailed specification, some further research and guesswork was required. The upshot was that the original “crossover” had plausibly contained a pair of passive low-pass filters that passed the low frequencies from each channel to the bass speaker (while mixing the bass component of the left and right channels in the process).

This action could be replicated by wiring a pair of commercially available low-pass filters in parallel with the left and right speaker outputs. The subwoofer filter boards I found online had an attenuation slope of 12 dB for frequencies above 120 Hz, an impedance of 4 ohms and an ample power rating of 400 W (see photos). It just remained to mount these securely and to wire them into the space behind the radio cassette in the centre console, where they just fitted. The trickiest part was persuading some new spade connectors to mate with the terminals on the old bass speaker, which is almost unreachable behind the glovebox.

Power on, and then, pleasingly, the bass speaker burst into life. It is surprising how well even an old subwoofer rounds out the bass from the door speakers.

This then leads to the final conundrum, which is to identify the easiest method of extracting the old bass speaker from under the dashboard in order to measure the fixing holes, carry out maintenance and/or consider possible replacement. Do I need to remove the glove box and the front passenger seat to gain access? Like the PO, I am anxious to avoid upsetting the interior trim. Suggestions would be welcome.

In the meantime, I can at least fill the cabin with 1970s bass from the original subwoofer.







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The base speaker is secured from the top of the dash meaning you would need to remove the leather in front of the screen. The proper way to do this is remove the screen and dash itself as the leather tucks under each. Also the screws are very close to the screen so access is poor with the screen in place.

Unless you are desperate to correct the base speaker I would leave it alone and explore other options for the door speakers.


The US cars had a Blaupunkt unit as above.


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Do or do not, there is no try! 


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Is there no way to drop the speaker down by getting access to the four fixing nuts (as per the photo), leaving the four bolts in place and finding a replacement speaker with compatible fixing holes?

Although I can see getting access to the four nuts is not going to be easy…and probably harder to put back than remove…

So your advice to leave well alone may be the best!

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You may be lucky as they are in good rust free condition so should spin free provided the screw doesn’t turn.

Mine have nylon nuts fitted and had glue on them.

I decided to just leave mine as it works but sound was pretty poor tbh.

Dave :) 


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Do or do not, there is no try! 


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  • Solution

Rudi here's some original type door speakers from Denmark. The bass speaker does come out from under the dash. Keep looking for a Hitachi Digital 1, they pop up now and then.

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  • 1 month later...

I bought the pair of SEAS-10-F-LG on eBay and they arrived yesterday in good condition. They are now fitted and are an excellent restoration back to the original sound system.

Many thanks to @v8vantage for spotting them.

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