Re-foaming the drive units of the Impulse H2 speaker

[Barry]

A friend of mine has discovered the bass driver of one of his Impulse H2 speakers needs re-foaming. Rather than take the entire speaker to someone who can do the work, is it possible to remove the drive units from the cabinet? Has anyone here done this, and how are the units attached: woodscrews or nuts and bolts?

Any information would be appreciated.

Thank you

[walpurgis]

Might be worth a chat with Paul at RFC. He's dealt with these. Doesn't look a difficult driver to remove or work on.

https://www.referencefidelitycomponents.co.uk/restoring-and-upgrading-impulse-h2-loudspeakers/

[Barry]

Yes, I did look at the RFC site. The STD code implies they are in, or near Dursley, South Gloucestershire, which may be drivable from North Wales where my friend lives.

He is thinking that it would be a good idea to have all the drive units of both speakers assessed and re-foamed.

[hifinutt]

Yes Paul has been poorly recently but getting back gradually. He is the right guy to do it or advise

[Lawrence001]

Yes, I did look at the RFC site. The STD code implies they are in, or near Dursley, South Gloucestershire, which may be drivable from North Wales where my friend lives.

He is thinking that it would be a good idea to have all the drive units of both speakers assessed and re-foamed.I think the foam in the tweeters can degrade too. The usual solution is to replace them with a better type, I think Paul does that on his upgraded H2s.

[hifinutt]

yes . he does . mine have original bass units and new tweeters and midrange

bit of background ideas

https://theartofsound.net/forum/showthread.php?57220-Impulse-h2-woofer-refoaming-a-couple-of-tips&highlight=impulse

The woofer surrounds in my Impulse H2 speakers were on their last legs, my finger went through them with ease, not surprising after 25 years of dailt use but a worry nevertheless. A quick search on the internet showed some great post linking back to a refurb by Reference Fidelity Components and you tube provided some great videos on replacing speaker surrounds so I thought why not give it a go - it doesnt look that difficult.

Its not !! the most tricky part was getting the drive units out - more of that later.

Ordered a pair of replacment surrounds from Good HiFi VOF (goodhifi.com/(speakerreapirsshop.nl) in the Netherlands, under 20 Euro, ordered Monday arrived Thursday. Great service.

Anita's sticky glue is widely available in the UK and worked fine. Its mighty hard to squeeze it out of the tube so I unscrewed the top and used a very small cheap paint brush.

Clothes pegs, non in the house but Wilko had them at £1 for 36 (36 per driver is good) I rermoved these from the drivers after about 1 hour as some were starting to stick to the unit, guess I used too much glue

Wood chisel I had one of these and it was very useful.

weight to hold the surround to the cone, this was a nightmare !! plant pots, saucers, saucepans find something the right size and not too heavy took ages. I ended up with something out of a fruit juicer. key internal/external diameter measurement needs to be 15.5/15.7 cm.

shimming and centring - everything seemed to line up fine so I didnt mess with this

removing the drive units.
Internet wisdom appears to be to lie the speakers on their backs I removed them in situ. the bass drive unit is a very tight fit to the case. With the 4 retaining bolts removed and the drive units still in the cabinets. I removing some of the foam surround and threaded some strong wire round the metal arms that support the drive unit rim. Holding the speakers still and I gave the wire a very strong tug. They popped out with some speed - anticipating this I had puts lots of padding round everything near by and held the wire tight.

I tried to unsolder the cables insitu but no joy so in the end I cut them off and retrimmed the cable. On the bench it took ages to get the terminals clean again. I solder removing tape or a suction pump would, no doubt, have helped. The solid core twisted Vector cable had been pushed through a hole in the terminal and squeezed tight against both sides then soldered

Time wise the first unit took 90 minutes from start to foam on the cone, the second one 30 minutes. 2 hours to let the glue set and then about 30 minutes all in for both units to glue and peg the surround to the chasis. left overnight to dry.

all is back in place now, bass sounds a bit tighter and deeper.

far easier than I first imagined, looking back the most difficult bit was unsoldering the old cable from the drive units

if you have some old Impulse speakers check the woofer cones ..........

I guess the crossovers come next

https://theartofsound.net/forum/showthread.php?63608-Impulse-h6-revamped-by-RFC&highlight=impulse

https://theartofsound.net/forum/showthread.php?71840-Impulse-H1-H2-Midrange-Drivers&highlight=impulse

[Mr.Ian]

A friend of mine has discovered the bass driver of one of his Impulse H2 speakers needs re-foaming. Rather than take the entire speaker to someone who can do the work, is it possible to remove the drive units from the cabinet? Has anyone here done this, and how are the units attached: woodscrews or nuts and bolts?

Any information would be appreciated.

Thank you

I replaced the foam on my h2s very easy. Tricky part was finding something thing the right size to apply a little pressure to the newly glued surface on the inner edge. Lots of clothes pegs on the outer edge

[Mr.Ian]

Drive units held in place by Allen bolts, unscrew lift out and cut the wire, solder back. Need something the right hight to rest driver on

[Mr.Ian]

Surrounds here, probably worth doing the mids too.
https://www.repairyourspeakers.com/en/foam-rubber-surrounds/other-manufactures/impulse/g-20000103

[killie99]

I’m sure there was a thread on PFM with a video and photos of how to fit new surrounds but I currently can’t find it, maybe someone else might be better at searching than me

[walpurgis]

Loads of videos on YouTube showing surround replacement.

[Barry]

My friend has spoken to Paul at RFC. Paul has been out of action (presumably due to a move of premises) and is only now getting back to work.

Whether my friend sends only the drive units back, or the entire speakers (including the cabinets) has yet to be decided.

Anyway thanks for all your comments and advice.

[hifinutt]

great . thanks for update