My time with the Impulse H6 speakers

[Audio Al]

I have owned these for a few months now and have just realised I have not swapped them with any of my other speakers during this time
They seem to suite my listening taste ,
They do so many things correctly ,
The bass is really good for the size of the driver ,
Being horn loaded must help with this ,
These are the first horn loaded speakers I have owned
Condition is mint , well worth my all day trip to collect and 600 miles
I am currently listening to Simple minds new gold dream half speed master LP

[Barry]

Yes, they're very good speakers. A friend of mine has a pair. One of the few folded horn speaker designs I can listen to.

[Reffc]

They're probably my favourite of the Impulse line up Al. Whilst they could never be accused of being the last word in neutrality, what they do well, they do really well. They are capable of eye-brow-raising results with a little fettering to provide lower distortion an octave each side of the crossover, and to improve polar response/imaging. The only concern is the tweeter (a matter of when and not if the voice coil bond with the inverted dome starts to break down). I have a collection of duff ones here and haven't yet decided whether they're worth doing anything with, but given what's on offer these days very reasonably, I suspect not. Highly entertaining loudspeakers

[Barry]

My friend's are at least 25 years old; no sign of any trouble with the tweeters. (Yet)

[Marco]

He doesn't play them loudly enough to cause the tweeters any problems

The only worry the tweeters have in those speakers is in developing 'lung cancer', having for the best part of those 25 years, 'inhaled' 20 fags-a-day!

Marco.

[Barry]

He doesn't play them loudly enough to cause the tweeters any problems

The only worry the tweeters have in those speakers is in developing 'lung cancer', having for the best part of those 25 years, 'inhaled' 20 fags-a-day!

Marco.

You should have seen the state of the Audio Innovations amplifier before he had to have it repaired! When it was collected, the repair man complained about the nasty, sticky patina of cigarette smoke tar, which took a long time to remove.

The owner has since given up smoking (at £300 a month it was proving to be too costly!).

[Marco]

I know, mate - I see (and have to deal with it) all the time when framing pictures!

Dave needs to find another way of 'enjoying' that £300 a month he's saved now, instead of simply topping up his bank balance, yet simultaneously claiming poverty!

Marco.

[Reffc]

My friend's are at least 25 years old; no sign of any trouble with the tweeters. (Yet)

Many taken to me have already failed though Barry. I get lots of healthy pairs in too but tbh, most people seems to prefer the SEAS conversions and know they'll last the next few decades hopefully without any problems.

[Barry]

Many taken to me have already failed though Barry. I get lots of healthy pairs in too but tbh, most people seems to prefer the SEAS conversions and know they'll last the next few decades hopefully without any problems.

Oh I'm not denying your experience Paul, it's just that tweeter failure on my friend's H6s hasn't as yet happened. Is the failure due to the vertical disposition of the tweeters?

Anyway, when it does occur I know where he can get help. The problem will be getting them there.

[Reffc]

Oh I'm not denying your experience Paul, it's just that tweeter failure on my friend's H6s hasn't as yet happened. Is the failure due to the vertical disposition of the tweeters?

Anyway, when it does occur I know where he can get help. The problem will be getting them there.

What seems to be happening is that the glue joint between the earlier kevlar inverted dome tweeters starts to break down, gets very brittle and starts to fail, setting up unwanted resonance to begin with (before it totally debonds) which can create audible distortion, before finally failing. The quick way to test is to set them up for a voicecoil "rub and buzz" test where a series of ever decreasing voltages are applied across a set frequency sweep and the resultant impedance curves are generated. A healthy tweeter should have smooth characteristic impedance curves with frequency across the range of voltages tested, whereas an unhealthy one will have very obvious spikes and dips along some or all of the impedance curves hinting that all is not well. Acoustic measurement usually confirms this with some very erratic plots.

I have tried re-gluing the voice coils but to clean all of the gunk and hardened glue from the delicate voicecoils and domes is a fiddly and time consuming business and they are so easily damaged too. The solvents will also affect both the voicecoil insulation and the resins within the kevlar matrix, and that's before you try and properly re-align them and try and use a glue which wont alter the effective mass of the coil and dome. It's a PITA to do properly so that they return to factory spec. I have done it, but it's cheaper and to my mind better just to replace them. There are many modern tweeters that simply out perform them for relatively little cost.