I have to admit i saw these and had to have them. I never seen anything like it before, these things were built in 1971 by goodmans. 4 Bass drivers with a passive 12inch bass assist, 2 mids and 2 tweeters.
So my aim is to give them some TLC, usual things like check the drivers, the crossovers could probably do with new parts etc.
Hoping someone out there has experience or knowledge to assist me! But i am really intrigued by these and want to have them running as Goodmans intended!
So my aim is to give them some TLC, usual things like check the drivers, the crossovers could probably do with new parts etc.
Hoping someone out there has experience or knowledge to assist me! But i am really intrigued by these and want to have them running as Goodmans intended!
Thanks Galu, the youtube videos were ok certainly gave me an idea.
I've started work on renovating them, took off the passive bass radiator to reveal the crossover.
Wiring could do with a tidy, my next move is to replace the old capacitors on the crossover. Would anything else need to be changed? Inductors never really have issues do they?
Capacitors are
4.7uf 63v
40MFD 50v
10MFD 50v
60MFD 50v
My thoughts were to buy ALCAP capacitors as they are a close match to the originals.
I have a dayton DAT V2 which will help me check all the drivers to, then all i need to do is tidy the enclosures and get them resprayed.
I've started work on renovating them, took off the passive bass radiator to reveal the crossover.
Wiring could do with a tidy, my next move is to replace the old capacitors on the crossover. Would anything else need to be changed? Inductors never really have issues do they?
Capacitors are
4.7uf 63v
40MFD 50v
10MFD 50v
60MFD 50v
My thoughts were to buy ALCAP capacitors as they are a close match to the originals.
I have a dayton DAT V2 which will help me check all the drivers to, then all i need to do is tidy the enclosures and get them resprayed.
Yes, those old electrolytic caps (Elcaps etc.) will need replaced. The crossover will have been tuned with the ESR of electrolytics in mind, so best stick to electrolytics such as Alcaps. Also consider the Mundorfs from Wilmslow Audio.
Mundorf Electrolytic ECap Capacitors
The inductors can be left alone.
The twisted pair wiring looks good to me and you would hear no benefit from changing it.
Mundorf Electrolytic ECap Capacitors
The inductors can be left alone.
The twisted pair wiring looks good to me and you would hear no benefit from changing it.
I think Goodmans must have been experimenting with some sort of drugs to come up with this design.Very weird sounding things.By no means bad-just very strange.Not so much deliberately obtuse as deliberately diffuse.
Hahaha well either way they were breaking boundaries with the design. Its well built, the drivers are solid and they put a great deal into it.
I like weird and wacky! These speakers were produced by Goodmans in its heyday so the quality of the drivers should not be in question.
The mixture of direct and reflected sound may not be to modern tastes in regard to imaging, but I'd love to be able to hear the resulting soundstage!
I hope, vishalk, that you will continue to report on the progress of your renovation.
The mixture of direct and reflected sound may not be to modern tastes in regard to imaging, but I'd love to be able to hear the resulting soundstage!
I hope, vishalk, that you will continue to report on the progress of your renovation.
Of course i will Galu! Im actually doing a youtube build to help others who like me and you, like wierd whacky and vintage goodmans gear.
I will be sure to update my progress on here.
I will be sure to update my progress on here.
Drivers removed
Speakers removed
The black plastic type seal over the passive bass cone was coming away had to be glued, stretched and held down until it dries
Same with midrange, over the years the glue somehow had weakened and the surround was coming away from the chassis.
Speakers removed
The black plastic type seal over the passive bass cone was coming away had to be glued, stretched and held down until it dries
Same with midrange, over the years the glue somehow had weakened and the surround was coming away from the chassis.
The above picture shows the midrange test on the dayton dat v2.
The green line showing the test before and the blue after glueing the surround down.
New capacitors for crossover.
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That's a common problem with drivers of this age. Also worth checking that the rear suspension spider is still securely glued to the driver basket - see attachment.
Attachments
Well spotted Galu from the graph produced it shows from around 400hz to 1.5khz isnt smooth even after glueing the surround.
I doubled checked the spider and it was fine, what i need notice though was as i moved the spider the voice coil was sliding up and down the cone/diaphragm! The glue here had also come away, so that has been glued now and hopefully i will do another test and it should be a smooth curve.
I doubled checked the spider and it was fine, what i need notice though was as i moved the spider the voice coil was sliding up and down the cone/diaphragm! The glue here had also come away, so that has been glued now and hopefully i will do another test and it should be a smooth curve.
Well spotted! Just don't put full power through those drivers until you're sure all's glued that's meant to be glued! 🙂
Every Driver has been thoroughly checked with the dayton dats v2, the bass drivers i will match them up closely.
I have glued and checked all parts where needed now!, next is to tackle the cabinets and get them filled, sanded and repainted.
Not to happy about the sponge dampening material, i have lots of polyfill and wool to thinking one cabinet i will leave standard and the other use poly acoustic wadding and see which one sounds better.
I have glued and checked all parts where needed now!, next is to tackle the cabinets and get them filled, sanded and repainted.
Not to happy about the sponge dampening material, i have lots of polyfill and wool to thinking one cabinet i will leave standard and the other use poly acoustic wadding and see which one sounds better.
Re; the overall design of these speakers. They are 'different' but may well be based or serious research. There is a paper by (Roy Allison? I think) in the JAES many yrs ago ('70's?) where he did extensive testing of speakers against walls and corners etc. I recall they had woofers near the boundaries. This generated a series of graphs that showed bass reinforcement in the lower octaves. I understand he marketed models based on this research. These Goodmans may have also been designed with that in mind.
Cheers Jonathan
Cheers Jonathan
Foam alters the sound quality at high frequencies, while wool felts alter the sound quality at lower frequencies.
At least that is what it says here:
How to Use Sound-Damping Materials in DIY Loudspeakers
Perhaps you could also experiment with a mixture of the two?
At least that is what it says here:
How to Use Sound-Damping Materials in DIY Loudspeakers
Perhaps you could also experiment with a mixture of the two?
Yes Galu that's worth thinking about because filling the enclosure will increase the effective volume and alter the low frequency response damping etc. But after all these yrs the T/S parameters of drivers and bass radiator are likely to have drifted a bit.......so the result will be like the marriage vows.....it will effect the speaker 'for better or worse' ha ha.