[mhennessy]

Hi Ian,

Many thanks for that - it must have taken you ages to compile! I've updated the list to include them:

• Goodmans (3 bolts): 18 (8 in RP18, 5 in RP25, 1 in AM Herald RP30, 1 in Jonster's AM Herald unnumbered - probably RP30, early RP10, Helsman RP36, Marine Herald RP32)
  
• Goodmans (no bolts): 11 (My RP25, 1 in AM Herald RP30, 3 AM Heralds RP35, 2 in Helsman RP36, 3 in VHF Herald RP37, 1 in Hunter RP38)
  
• Celestion (silver frame): 6 (3 in Sovereign RP25, 1 in RP25A, 2 in VHF Herald RP37A)
  
• Celestion (black frame): 4 (3 in Sovereign RP25B, 1 in VHF Herald RP37A)
  
• Elac (large magnet): 3 (VHF Herald RP37A)
  
• Elac (small magnet): 2 (Hunter RP38A)

* The AM Herald RP30 having a no-bolt Goodmans seems a bit anomalous, but this set is incomplete, and it's possibly not the original speaker. More on that when it arrives...

So your results reinforce my conclusions pretty well - many thanks again.

I would correct my earlier point:

• Or, the Goodmans speakers were used exclusively until the advent of the T309 tuner (RP25A and RP37A)?

It's clear that Hacker started using the Celestion in the RP25 before the tuner change. So far, the data shows that all RP37s have a Goodmans speaker, so I'd be interested to hear from anyone with an RP37 with a Celestion speaker.

Updated conclusions - changes in bold:

1. The Goodmans speaker was the "general purpose" model that was used in most models. It is available in two versions: the earlier version had 3 bolts, later ones don't, and it's available in at least two impedances.
   
2. The large magnet Elac was only fitted to RP37A VHF Heralds.
   
3. The Celestions were only fitted to later RP25 Sovereigns and VHF Heralds (probably only RP37A. Later versions had a black chassis.
   
4. An RP25 might have an early Goodmans with bolts, the later Goodmans sans bolts*, or a Celestion! I presume it depends on serial number, along with the usual production variances - trying to drill down further might be going too far
   
5. RP25As and Bs should have the Celestion speaker... There's every chance that speakers in the RP25B sets will have a black frame.
   
6. Finally, the Elac with the small magnet and gold-coloured frame/magnet was fitted to RP38A Hunters, and possibly later models throughout the 1970s (although according to the 1975 brochure, all other sets had a smaller 5 by 7" speaker, but from the pictures I've seen, I'm pretty sure it's still made by Elac).

* The only RP25 I know about with a no-bolts Goodmans is my set. Is my speaker non-original - perhaps they switched straight from bolted-Goodmans to the Celestion?

Thanks as always,

Mark