Goodmans 18 HP xmax (etc... )
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Category: Other Chat
Forum Name: Golden oldies
Forum Description: Post all historic interesting items, stories and photos here (no, not your Nan)
URL: https://forum.speakerplans.com/forum_posts.asp?TID=108864
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Topic: Goodmans 18 HP xmax (etc... )
Posted By: bob4
Subject: Goodmans 18 HP xmax (etc... )
Date Posted: 04 January 2025 at 10:23am
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Friend of mine has a couple of these old beasts kicking around. The brochures of yesteryear available on the net don't provide any parameters, probably because they predate the work of Thiele and Small. Does anyone on here have a vague idea of the xmax and xvar/xmech of the 18 HP? Iirc they claim 25 Hz resonance  Any input would be highly appreciated! Power wise I am aware that they are frail, they will be driven with suitably specced amps (100-200w rms @8 ohm) Apologies for the bad picture. Hopefully you can glean something despite the grill.  |
Replies:
Posted By: jbl_man
Date Posted: 04 January 2025 at 1:26pm
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Goodmans 18p has a paper cone, and a doped paper surround. Xmax is irrelevant with these. Power handling was 100 watts at best, and given fifty-year old adhesives, 50w would be about the limit today. 3 inch voice coil.They are quite efficient for an 18-inch though. Was mainly intended to be a bass guitar/organ speaker, so has some useful lower-mid sounds. I did buy a couple of these new around 1976, were only about £45, those were the days! ------------- Be seeing you. |
Posted By: slaz
Date Posted: 04 January 2025 at 8:18pm
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I have a couple of the 18HP in the shed .... both need a bit of attention. One has a small hole/rip in the cone (which I'm fairly sure could be repaired well) and the other has a terminal missing (but the tinsel wire is OK). I've tested both at very small power in free air, and both basically work. Not sure what to do with em - can't bring myself to chuck em .... any ideas anyone ? Re the 50-yo adhesives - yeah I hear you .... well - dunno. They've been stored in a totally dry, ventilated place. Mine are the HP version - prob a bit younger - 8ohms 230W is on the label. ------------- REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON |
Posted By: bob4
Date Posted: 04 January 2025 at 9:51pm
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Here is another picture. They are Pro Power series HP 18 Anyone care to share actual experiences of using these, what they are capable, what are the limits? For example, is there a risk of easily damaging the voice coil former with overexcursion? Does anyone know the dimensions of the voice coil, clearance from the pole plate etc........ I remember talk about using these in quad wardrobes, run off 600w kt88 tube amps..... they must move some air?
Edit: and furthermore, are these the frames people talk about being reconed by wembley speakers?  |
Posted By: jbl_man
Date Posted: 05 January 2025 at 9:01am
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That is the later model, the one i was refering to was the earlier 18p. The one you have would have been mid-80s. Yup, higher power rating. Will still be the same 3 inch coil i expect. ------------- Be seeing you. |
Posted By: Contour
Date Posted: 05 January 2025 at 10:10am
| I would suspect 200-400 W RMS power would be fine for these. Old stuff, but quality, just use it. |
Posted By: jbl_man
Date Posted: 05 January 2025 at 10:20am
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I have found the original 1984 brochure, it lists both the earlier 18p and later 18HP drivers. http://www.ajaudio.co.uk/GOODMANS%20POWER%20RANGE%20CATALOGUE%201984.pdf" rel="nofollow - http://www.ajaudio.co.uk/GOODMANS%20POWER%20RANGE%20CATALOGUE%201984.pdf ------------- Be seeing you. |
Posted By: Robbo
Date Posted: 05 January 2025 at 11:04am
| I seem to remember that the blue chassis 18P shown above was the basis for Wembleys own 18" sub range of cabinets from back in the seventies---IIRC they uprated both the voice coil and cone assembly to make them a much better driver compared to most on the market back then. |
Posted By: bob4
Date Posted: 05 January 2025 at 11:08am
Thank you for the link. This is the brochure/material I was referring to. Meanwhile I simulated the suggested cabinet and slot port, and apparently this yields a box tuning of 35 Hz for the Power Pro 18 HP !!! |
jbl_man wrote:Posted By: bob4
Date Posted: 05 January 2025 at 11:10am
Thank you for this bit of information! So this might suggest that the internal magnet structure geometry is not per se a restricting factor in this case?
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Posted By: knet94
Date Posted: 05 January 2025 at 3:51pm
| Nice trip down memory lane. I've still got 4 of the 15HPs. I always thought it odd that they were rated at 250 watts whilst the 18HP was 230 watts. |
Posted By: VECTORDJ
Date Posted: 09 January 2025 at 4:14pm
| LOVE OLD SCHOOL GEAR...A+....VECTORSONICS |
Posted By: madboffin
Date Posted: 09 January 2025 at 5:47pm
That was more than a week's wages...
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Posted By: Robbo
Date Posted: 09 January 2025 at 7:05pm
| I am sure that we used to have some really old Martin VRS cabinets used for sidefills and the 18" bass drivers were based on that Goodmans chassis. |
Posted By: madboffin
Date Posted: 10 January 2025 at 10:13pm
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If they were VRS1000 cabinets with the origianl drivers, they were probably Celestion B18-1000. They had a distinctive double spider suspension and were exceptionally good. They were actually designed to go in that cabinet, but became part of Celestion's standard product range. I think Dave Martin decided not to take out an "exclusive" deal as the production quantities weren't going to be enough to justify it. Some Martin 2x18 bins were also fitted with them. They were never a big seller for Celestion, probably because it was very expensive (although worth it) and Celestion wasn't generally known as a maker of such up-market drivers. |