Impulse H2's

Brumjam

Quite why I don't know, but earlier this week I bought a pair of H2's off eBay. They're in fairly tatty condition and have no internal wadding, but I'm quiet impressed with them so far . Has anyone heard these speakers? I have them right against the wall which provides useful reinforcement to the bass. They're a very easy load for my amplifier and would probably go very loud with just a couple of watts.

Docfoster

I have not.
I like their look tho. A slightly different way of doing things...?

uglymusic

Impulses. I remember them in their heyday. In fact, I had a pair of H6s (the H2s' smaller brother) for quite a while. I think I've said here before I hanker after trying a pair of H2s - current domestic circumstances couldn't give them a home, though.

I seem to remember the big Impulses being used against a wall, so I think that's no surprise. And as they're horns, I wouldn't be looking for internal wadding. 

Brumjam

Apparently Impulse used to apply a small amount of wadding as standard. This approach is different to my other horns which have no wadding, but in fairness they're somewhat different being a 3-way folded horn with a wideband driver.

I'm listening at a distance of three metres and the driver integration appears seamless. They're the first speaker I've owned that can really pressurise my listening space as well - suitably impressed so far. My only minor reservation is their slightly forward presentation. This is only noticeable with poor quality recordings and can perhaps be tamed via the crossover.

uglymusic

I don't remember wadding in the H6s, but I'm sure you can find an H2 owner who can tell you exactly how the H2s should be set up.

Impulses are (were) definitely forward in their presentation. Much to my liking. 

Now I am getting jealous!

uglymusic

How are the H2s James?

Alan

H2s. Near the top of my bucket list, enjoy!

Brumjam

Here are my initial thoughts after a few hours listening...

The good: enormous dynamics...these speakers can really pressurise my listening room in a way I've not heard before. They sound very open, immediate and fast. Well recorded tracks are a pleasure to play......

The bad
....average recordings sound terrible! I also think the tweeter (to my ears) is too forward compared to the mid and bass driver. After a few hours I find myself wanting to retreat to the easy going nature of my normal speakers. These particular H2's have non-standard crossovers and there's signs of further tinkering with respect to the binding posts and internal wiring. Therefore it's hard to assess whether the modifications are causing the tweeter to be overly prominent or whether it's meant to be like that - I suspect the latter to be honest.

I'm going to get them returned to standard in a few weeks and then I can further evaluate. It has been an eye opening experience in terms of them exposing flaws in my current speakers - something I didn't want to hear, but it has set me on the road of shortlisting speakers that perhaps offer the best of both worlds.

uglymusic

That sounds like my remembered experience of the H6s. I used to scare people by playing the Red Hot Chili Peppers' Blood Sugar Sex Magic at ear-splitting levels, with the bass and drums feeling visceral.

To get a pair in my present house, I'd need to get some soundproofing.

Have you tried Googling for reviews? They should give you some feel for what the original balance was.

Brumjam

Having a go at refoaming the bass drivers tonight. The wadding behind the bass drivers has dropped down below where it looks like it should be. There's also evidence that the drivers themselves are past their best- I think that Audio Note use the same driver so should be easy to find replacements. Someone has gone all Audio Note with the internal wiring. Lots to get fixed, but I'm warming to their sound even in current condition.

uglymusic

I hope the reforming went well James.

Brumjam

The H2's are off on a trip to the hifi wigwam show today.  I've changed out the input valves in my amp for some NOS Amperex vintage wotsits which has helped take the edginess away - still borderline forward treble but it's sweeter with the new toobs.

uglymusic

Have fun!

Brumjam

My H2's are now down in sunny Gloucestershire with Paul while he brings them back from the brink. New tweeters will be fitted along with external crossovers. Cosmetically the veneer is being replaced with white oak and all cloth is to be replaced as it was ruined.

Docfoster

My H2's are now down in sunny Gloucestershire with Paul while he brings them back from the brink. New tweeters will be fitted along with external crossovers. Cosmetically the veneer is being replaced with white oak and all cloth is to be replaced as it was ruined.

Delighted to read this. :-)
I'm expecting great things on your behalf.
(No pressure Paul.)

uglymusic

My H2's are now down in sunny Gloucestershire with Paul while he brings them back from the brink. New tweeters will be fitted along with external crossovers. Cosmetically the veneer is being replaced with white oak and all cloth is to be replaced as it was ruined.

Now I am jealous!

Sounds like a brilliant idea.

PAC

Sorry for my tardy late response  ">

I've had a chance to evaluate Jame's lovely old H2's and there were indeed a number of "issues".  Whilst most horn designs shouldn't use any internal wadding (unlike transmission line designs), Impulse supplied a little with the H2's which I guess was a way of a) modifying the driver impedance (hence output) characteristics for room tuning and 2) for placement directly behind the main driver on the rear of the horn (just a little).

These have had some recovering work done in the past with the covered side panels being (badly) refitted.  They are all loose but one speaker has already come apart for refurb anyway.  The mid horn was held in by two captive screws at the rear but this pair have had glue put in the rebate where the mid horn slides in.  the glue joint on one has failed and the mid horn is free to move around with free will 

8-}

The internal wiring has been butchered up by a bodge job fitting in cable which is way too thick and inflexible for the drivers.  What difference 1m of cable would make, irrespective of the brand, is questionable. All that was needed was a decent quality OFC which should ideally be very flexible and light so as not to over strain the delicate terminals.

It has all proved too much for the mid terminals, one side of which has been torn off its hardboard mounting and was found dangling by the wire attached to the cone.  That has been swiftly epoxied back into place as a permanent repair and the terminals all strengthened to take the additional strain of the ships jump start cable used to wire these up!

The woofers are in good shape and the refoaming was a good job by James 

=D>

Tweeters are later replacement TC120 TiOxide coated jobbies minus their impedance modifying bar which looks like it's been removed.  They have a nasty sting in the tail at around 15 to 18KHz, which whilst on the cusp of what most of us can hear would add a significant top end lift which could accentuate the forward sounding nature James experienced.  The mid woofers have also a bit of a rise just above crossover.

My recomendation would in this case be to replace the tweeters with something newer having a far more linear and smoother response which means fewer crossover components needed to engineer a better sound quality, which is always a good thing if possible. Replacement tweeters by Seas would do the trick for a relatively inexpensive sum.

Crossovers can be removed to external enclosures allowing quality air cored inductors of low DCR to be used for mid and HF drivers.

The Oak veneer is already en-route, a new base is being constructed to take new inserts for spikes (the original has suffered a little) and the cloth for recovering will be here next week.

Its a pretty mammoth job!

Docfoster

Ah, I can see you're delighting in the creative challenges presented here Paul.
As always, I'm genuinely interested in progress. :-)

Brumjam

Paul has managed to source NOS replacement midrange drivers =D> . The speakers will now have new/improved Seas tweeters and brand spanking new midrange units. I'm salivating at the prospect of hearing such a pimped pair of H2's 8-} Pics below (courtesy of Paul) showing the new veneer:

Brumjam

Docfoster

Bastard.

uglymusic

Where arenyou going to put them? Are you having a speaker annexe built?

Brumjam

A speaker annexe would be useful.  More pics courtesy of Paul the speaker magician:

NOS replacement mid driver compared to the original:

Untreated veneer in place......

PAC

No piccies showing James...lets see:

New mid driver:

Docfoster

Enjoying this. :-)
Keep these updates coming...

PAC

Docfoster

=D> =D> =D> =D> =D> =D> =D> =D> =D> =D>

Brumjam

These are looking brilliant Paul. I like the way you've installed the new tweeters....you'd never know the original design was any different.

Docfoster

Have you had chance to listen yet Paul...?

PAC

These are looking brilliant Paul. I like the way you've installed the new tweeters....you'd never know the original design was any different.

That was the aim James so hopefully they'll not draw too much attention from the original design.

I haven't listened yet Ben as the crossovers haven't yet been modified for the new mid/tweeter. That's a job for next week which will need impedance and acoustic responses for each new driver measured and the outputs put into a simulator so that I can have a play with values to ensure things like phase are got spot on between drivers.  It's then a case of building the prototypes and fine tuning by ear.  The bass inductor value remains as-is.

Docfoster

Agreed. The subtle space around the tweeter is actually quite nice. Could easily be designed like that...
Why didn't my Goodmans get one?!

And of course! Crossover-time. They're not yet ripe for the listening.

PAC

Ah, but you got a Batman cape around your tweeters! (ooh-err)

Docfoster

True. True.
I suppose a cape is as good as a halo...

sovereign

Very nice Paul, I always like looking at your work.

PAC

Thanks James. Big pair of OBs perhaps coming up next week for a rebuild...more up your street I suspect 

AntiCrap

Paul nice work.

PAC

Thanks Col.

Am just modelling the crossover design having measured both impedance and raw driver responses (drivers in cabinets).  The original exhibited a fair amount of comb filtering partly due to driver layout and design of cabs (so not a lot to be done there) but also when importing original design values for filters, its evident that these would have been voiced by ear with little if any analysis.  I've managed to simplify the circuit slightly and raise the impedance dip seen by the amplifier (at around 1KHz) where the original models at about 2 Ohms load!  This was simply done by adding a series resistor for the mid which damps the 1 to 1.3KHz spike in response as well as raising the load seen by the amp to something more sensible (5 Ohms).  Tweeter L pad has been replaced with a simple series resistor prior to the filter.  Next step is to build a prototype filter and see how they sound.

uglymusic

They're looking wonderful. Could be my dream speakers.

sovereign

Thanks James. Big pair of OBs perhaps coming up next week for a rebuild...more up your street I suspect 

Sounds interesting Paul

PAC

H2 external crossover boxes taking shape.  These are heavy so don't drop them on your toe James

PAC

Brumjam

Will have to think of a way to explain these additional boxes away to SWMBO :-?

Docfoster

Will have to think of a way to explain these additional boxes away to SWMBO :-?

...Could they be boxes of chocolate biscuits...?

PAC

That's where James will hide his hifi cash stash Ben...get with it!

PAC

On the home straight now:

PAC

$64,000,000...................................................How do they sound?

SENSATIONAL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 

Docfoster

Cripes.
@-)

...and Paul, you seem pleased! =D>

Docfoster

I've really enjoyed this thread since James initial post back in March. >:D<

sovereign

Looks great Paul.
My xovers are sat on the bottom of the box section of my bass driver. I see a lot of your xovers are external, what do you think the advantage of this is ?

PAC

several reasons James including getting things like inductors well away from the driver magnetic fields, removing them (as they can be microphonic) away from the resonance of the cabinets and direct radiation of drive units.  Also because I favour the spacing that external layout allows for things like air cored inductors and finally because and changes or future upgrades are made easy.

sovereign

Thanks Paul. I thought as much, just wanted to make sure what I had read wasn't BS. LOOKING GOOD