Roll on Saturday when I get to hear these in action. They sounded pretty good (if a little shouty) before the RFC treatment. Looking forward to hearing this turbocharged version B-).
At this juncture I am going to rub salt into wounds and say I'm having a last listen to these before James comes to claim them back, and enjoying every minute of it :P
James has just left the building. H2s now gone and very sorry to see them go.
Hope you enjoy them James; they certainly made an impact with me, in more ways than one (bad back and various other injuries involved in the resto work!). Great sounding speakers.
James has just left the building. H2s now gone and very sorry to see them go.
Hope you enjoy them James; they certainly made an impact with me, in more ways than one (bad back and various other injuries involved in the resto work!). Great sounding speakers.
The H2's have been in constant use for the last couple of days and I'm pleased to report they've far exceeded my expectations :-B
Paul has managed to retain the H2's speed and dynamics, while reigning in the strident treble/upper mids and providing a useful dose of thunderous bass. The H2's always sounded a bit lightweight in my room but not any more! There's no wimping out now with Massive Attack's 'Angel' opener on Mezzanine. The H2's can provide window rattling bass without smearing the mid or treble frequencies which stand out clearly in the mix. I had them extremely loud today and it was only at deafening levels that you can here limitations in the original cabinet design. At sane to loud levels they remain composed with all types music.
Eric Bibb's guitar (live à Fip) sounds startlingly realistic and the much improved imaging gives you a real sense of the venue's acoustic. They even make Dire Straits sound good!
Paul treats every pair of speakers like they are his own - the care and attention to detail is remarkable. Sincere thanks for the effort that's gone into these Paul =D> . I owe you a pint (when your back is better)!
PS any fellow Impulse H2/Ta'us owners who are interested in hearing these speakers are more than welcome to pop round for a listen....just send me a PM.
if you consider mounting an 18 inch ANYTHING on the sides of those H2's, I'll be sending you my Chiropractors' bill :P
There's been a few comments banded about (not this forum I hasten to add!) about the refurbishment changing them into something that "aren't H2s any more".
To answer that here (as I am not a member on the "other" site), there is no real change to the performance or characteristics of the bass horn nor to the mid horn. If people did their homework, they'd realise that the replacement mid unit is a re-worked version of the original Seas unit using a rubber roll surround, and has very similar impedance and acoustic properties, so nothing's been significantly altered there.
The tweeter replacement was done partly on James' request but partly because off axis, despite the claims made by Focal inverted dome advocates, measured response shows a few anomalies from 45 degrees off axis outwards which will affect the reverberant field/imaging. This may have been due to issues with the tweeters tested because I have not been able to test a NOS pair to date. This is made doubly worse in H6/Lali models which I've tested, where crossover is high enough to cause quite a step in off axis response.
The initial reason for the higher crossover point I'm guessing was to ensure higher power handling but times have moved on, and better tweeters with improved power handling and low distortion exist today so it makes perfect sense if spending money on something you want to keep and to enjoy, to make it as good as you can. I have never been a big fan of the kevlar inverted dome tweeters as I've seen too many de laminate from the voice coil glue bond and exhibit high distortion as a result, plus they don't have the most even response with what appears to be a marked break up resonance within the audible band.
Later Focal units addressed this and used an impedance/phase modifying bar across the tweeter. These did perform better but cannot be had for love nor money, so the sensible solution if upgrading is to use a decent modern production tweeter with as good off axis response as possible, and decent power handling (enabling a lower crossover point for the two-way designs, allowing a reduction in the polar step response between drive units, which improves imaging and accuracy).
None of these (sensible) changes really alters the character of the H2s, rather they build on its strengths and offer improved on and off axis performance. It is, however, totally understandable, that purists may look on in horror as the original design has been tinkered with, but I'm hoping that the original designer (who I know has heard this pair not that long ago) might approve if he were to audition them now. I applaud the design of the H2, and have a real soft spot for the Lali/H6 and Taus too. The crossover, as far as was possible, mirrors the topology of the original with one or two component value changes necessary for the driver changes, and has been simplified by using a series resistor prior to the HF filter (rather then L-pad) to both raise HF impedance to ensure a nominally flat response as well as sensitivity match between drivers. Some sensitivity modification was also carried out for the mid driver for similar reasons as the original circuit on these showed both a large step in mid response as well as an alarming dip in system impedance which whilst remaining highly sensitive, presented the driving amplifier with a very low impedance load.
In every respect these modified H2s imho better the ones delivered to me. James, as the new owner, I'm sure can (and has) attested to the sonic improvements without loss of the immediacy, punch and sensitivity that these are famous for. Hopefully that sets the store straight
I have no idea what is being said elsewhere. From what James and you say, it seems like you struck a very carefully considered balance between maintaining the worthwhile design fundamentals of the H2 design on one hand, and on the other improving the sound based on more recent techonologies (and your own skill). I'm assuming James just wanted his speakers to sound as good as possible. >-
I have no idea what is being said elsewhere. From what James and you say, it seems like you struck a very carefully considered balance between maintaining the worthwhile design fundamentals of the H2 design on one hand, and on the other improving the sound based on more recent techonologies (and your own skill). I'm assuming James just wanted his speakers to sound as good as possible. >-
Not sure if this thread is ended, however I was googling to find out how to resolve distortion in my Impulse H2's and found the marvellous thread above. My H2 speakers are completely original but distortion appeared recently and it turns out the foam surrounds had rotted. I've change the foam on the bass and purchased replacement mids, which I found online, following the guidance above. Pretty amazing improvement. Now need to decide what to do with the tweeters, which are the original Focal Kevlar inverted and are showing a certain distortion on powerful output recordings such as DVD Audio. I dont have the capability to remodel crossover components to replace with a modern tweeter.
Hi Eric.
Welcome!
Sounds like you're progressing things for your H2s. :-)
I'd suggest you contact Paul directly at his RFC website. He's your man, and he's withdrawn from forum life in recent times.
Thanks Doc,I wil contact Paul to thank him. Actually after further listening, I am not hearing distortion generally, just amazing clarity. What may be happening is the rebuilt H2's were revealing what I now believe could be distortion in the recording of one track on Alicia Keys DVD Audio, which I used as the first test album after the rebuild. Shock, horror, I could not believe a supposedly audiophile DVD Audio could be recorded with distortion in the 'shouty' parts of Keys' vocal, but I've tried listening to the same track on a Pioneer Elite AV amp through the Impulse H2's and the distortion is just about audible but smoothed over.
Overall, I like vocal transparency and am willing to trade my system being overly revealing of source limitations. I usually listen to the H2's through an upgraded (Black Gates, silver wire) Audionote Kit 1 and homemade silver cables.
Given that I can listen to Susan Boyle at high volume with absolutely no sibilance, and with Adele's '25' I can imagine I am staring directly at her vocal cords!, I'm fairly confident it's time to put down the soldering iron and enjoy.
You'll get through the 'I can't stand the distortion' phase eventually.
Various tweaks and new gear from Colin have rendered my system like an audio magnifying glass. I still occasionally notice something annoying, but mostly I've got to the stage where I ignore them automatically. The overall transparency is, on balance, totally worth having.
You'll never get through the "I can't stand the distortion" with standard H2's unfortunately Dave. Phase issues, comb filtering and a very forward mid response (try +12dB in free space) are all responsible and require a rethink and changes to the crossover design. The standard design also shows an amp-busting dip at 1.6KHz of just 2.2 Ohms for a load that is optimistically stated as "8 Ohms". This coincides with mid vocals, and many people using low output valve amps, especially SE amps, report significant audible distortion in this area, unsurprisingly!
Ever since I put some of Colin's better cables in my system, I've been able to hear all kinds of stuff, which is a first distracting, but in time I get back to listening to the music.
But you're saying the distortion here is due to the speaker's electronics, and it's inherently so bad with H2s and some amps that you'll never through the distraction? Yikes!
That's exactly it Dave. They're rather unique loudspeakers and what they do well, they do very well, but linear and in phase, they are not, and the impedance profile is like the Alps. Once that mid is reigned in, and the tweeter balance adjusted to suit, you lose some sensitivity and efficiency but gain a more linear and rewarding response that doesn't shout at you or make your ears bleed. I also have a re-designed crossover for them which improved polar response and coherence/clarity as it doesn't run the woofer quite so high plus addresses some of the phasing issues.
personally, I prefer them with an alternative tweeter. I was never a fan of the Focal inverted dome and many early Kevlar ones suffer the incurable issue of brittle glue joints with the voice coils starting to break down which is both audible and measurable in the distortion it adds right up until eventual failure.
The mids suffer two issues: Firstly the foam surrounds disintegrate, and ALL original ones by now will need refoaming, even if they look ok, its likely that it's just the doping compound holding them together. The second issue is fine sand collecting on the doped surface where it's impossible to remove it. This alters the effective mass of the cone and alters their response. Where does the sand originate? It was used to fill the annulus between formed horn and MDF carcass as a damping material, and when owners use the horn mouth as a convenient handle for moving or lifting speakers (as many seem to!), the horn joints fail (crack) and even a small hair line crack is sufficient to shed this fine sand. beware, H2 owners....never lift the speakers by using the mid horns!
You can either keep 'em standard by very painstakingly cleaning up the edges of the original mids using Acetone and a scalpel (allow 2.5 to 3 hours per drive unit minimum) and refoaming, or you can replace with the newer NOS H543 SEAS unit (no longer in production), which requires very slight crossover changes for integration. It's pretty similar in response but better balanced and better damped thanks to a rethink and the use of a factory formed self damped surface, plus uses new rubberised surrounds which won't rot. I have limited stocks remaining here if anyone wants them (I am the sole UK supplier of remaining SEAS stock for these and bought the last ones up from the distributor to safeguard H2 owners!).
It sounds like a lot of work, but I'm sure it's worth it. Maybe I need to find an excuse to go up and see James (Brumjam) and hear his.
As I've mentioned before, I used a pair of H6s for quite a while and loved them, warts and all. I've hankered after a pair of H2s, but I think I'd blow myself on to the ramparts of Arundel castle with the current SECAs!
H6s can be lovely things but again, are not phase accurate and are rather muddled with that mid-bass being run way too high. It kills imaging potential too with the waist in mid response, plus they lack coherence standard. Fettled and with some inexpensive SEAS tweeters fitted, and a properly designed crossover that is phase accurate, they are transformed, and exceptional in sound and value terms. It would be interesting to get your thoughts on Jame's H2s. I'm working on several pairs as we speak...
You're right, H6s could be muddled and the frequency response could be all over the place. Their directness really connects you to the music, though, as I remember.
I'm glad you're finding a market for H2 mods, and that they're being given a new lease of life.
I'd love to come up and hear them, James. It'll need some arranging from this end - and, no doubt, from yours.
Have you bought the F6, or do you have it on loan?
I built it Dave using PCB boards from DIYaudio. It's a push-pull 25w class A design....nice and toasty for cold winter nights.
I don't think I've heard a Nelson Pass Class A. Strange thing is, some years ago, when I was looking at a pair of H2s on eBay, I wondered what to drive them with. Not wanting to go tube, I Googled and found Nelson's designs. I didn't bid on the H2s for some reason, and so didn't go down that route.
Now I have my 30 watt SECA monoblocks, I find myself thinking about horns again.
Comments
Looking forward to knowing what Santa's gifts sound like! <:-P
We await James' thoughts...
:-c
Paul has managed to retain the H2's speed and dynamics, while reigning in the strident treble/upper mids and providing a useful dose of thunderous bass. The H2's always sounded a bit lightweight in my room but not any more! There's no wimping out now with Massive Attack's 'Angel' opener on Mezzanine. The H2's can provide window rattling bass without smearing the mid or treble frequencies which stand out clearly in the mix. I had them extremely loud today and it was only at deafening levels that you can here limitations in the original cabinet design. At sane to loud levels they remain composed with all types music.
Eric Bibb's guitar (live à Fip) sounds startlingly realistic and the much improved imaging gives you a real sense of the venue's acoustic. They even make Dire Straits sound good!
Paul treats every pair of speakers like they are his own - the care and attention to detail is remarkable. Sincere thanks for the effort that's gone into these Paul =D> . I owe you a pint (when your back is better)!
You're clearly delighted.
I second your comments on Paul's attention to detail and love of his work.
=D>
[-O<
Just £15 now. Collection from Reading...
:-SS
From what James and you say, it seems like you struck a very carefully considered balance between maintaining the worthwhile design fundamentals of the H2 design on one hand, and on the other improving the sound based on more recent techonologies (and your own skill).
I'm assuming James just wanted his speakers to sound as good as possible.
I'm interested to hear some big JBL's in comparison to my H2's.....something like the JBL 4429 which is as big as I could go in my room.
FWIW (not a lot, I know), I've never liked JBLs.