Allison 6 Refurb.

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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Thu Dec 21, 2017 9:14 pm

I discovered that I had one speaker plugged into the 8 ohm outlet and the other into the 4 ohm on the amp. Needless to say this did little for the sound stage. I have corrected this and done a bit of speaker repositioning plus a hint of toe-in. On 50cm stands the sound stage is some four to five feet above the speakers with vocalists a little higher than this. This is good for my system but also quite possible for a well sorted P&S system. More positioning adjustments needed to get the extra width I know is possible from my system - it's currently about as wide as the speakers but can go a foot or more outside them on a good day when Mr Scottish Power co-operates with a nice clean supply.

The green Russian caps are proving to be very smooth and non-fatiguing, to the point that reducing the resistor down to 6.8 ohms is worth a try, It seems those cheapo caps were responsible for quite a bit of the top end brashness.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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karatestu
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Re: Allison 6 Refurb.

Unread post by karatestu » Fri Dec 22, 2017 9:11 am

So Simon, are you happy with the semi Omni presentation or is it back to P&S for you ?

Soundstage and imaging was never that important to me but is nice. Surely some of it is to do with the recording but if you have a smaller soundstage than before then something is amiss. A new room is probably part of it too so positioning may take a bit of experimentation.

Positioning is something I have never had a problem with although in a home setting you can only do your best with what space is available and what life (and wife) allows.
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Fri Dec 22, 2017 10:37 am

I cannot see me going back to P&S Stu. The main reason is the bass performance and the positioning needed for so many P&S speakers. Speakers stuck a meter or so into the room are just impractical for me and the consequent peaks & troughs in the bass performance with so many speakers are an issue. The last change of position brought about significant improvements and there's now more I can do, having move more bits of furniture. I'm after width and height as much as depth and the height part is now very good & better than any of my P&S setups.

For the small investment made so far (about £150) including drivers and new caps it sounds better than it has any right to, at least when compared with something new anyway. I've plumbed in my HT MJ Acoustics subwoofer as an experiment - verdict awaited!
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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karatestu
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Re: Allison 6 Refurb.

Unread post by karatestu » Fri Dec 22, 2017 8:46 pm

I am glad you have made progress. Point & squirt is yesterday's technology :grin:

Subwoofer - what's the verdict ? Cant be compared to a doped bass driver with a direct connection to power amp though. :naughty:
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Fri Dec 22, 2017 11:31 pm

Yes indeed, I suspect it's going to be a poor substitute for a BBC. The problem is that it operates at the very bottom of the audio spectrum - I set my XO to 40hz. The bass from it lacks texture and definition - as one would expect I guess. However, lack of steel lining will also be playing a part.

I now have 5.6 ohms padding in. Much better overall. Those cheapo caps certainly have a lot to answer for. Lana Del Rey's voice is emanating from a height of about six feet with the instrumentation laid out below. It's a heavily processed album, but the top end is hanging in there. A bit of Faithless - God is a DJ is also playing fine, albeit with the cabs joining in a bit. The bottom line is that it's pretty true to the source material

So it's steel next, then the BBCs However, until then it's perfectly listenable to.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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karatestu
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Re: Allison 6 Refurb.

Unread post by karatestu » Sat Dec 23, 2017 8:28 am

If you like lots of lovely bass texture and definition then you need to have a play around with isobarics sometime. That was a real eye opener as far as bass texture, definition and detail are concerned.

However, the doped 12inchers you have will be more than good enough especially if slightly overdamped and box steel lined.

I am enjoying this thread nearly as much as my own.
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sat Dec 23, 2017 12:31 pm

That's certainly the thinking re. 12 inchers. I'll be going for 25mm plywood and some overdamping. A BBC volume of 55 litres gives a Q of 0.46 with my drivers which should be ideal for my needs. With the driver at the bottom of the front panel and close to wall positioning the bass ought to be OK thanks to the early fall-off from the overdamping. IIRC the donor speakers were designed for close to wall positioning and had a cabinet volume of 57 litres minus a bit for the midrange sub-enclosure. So, something like internal dimensions of 62x30x30 should be fine. There's then the small matter of powering them!
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sun Dec 24, 2017 1:04 am

It's all settling down very nicely. The 5.6 ohms is just right with those big green Russian caps. Soundstage is high and wide now I have the positioning right - about 2cm from the wall at the inside corner and about 4cm out from the outer corner, so just a modest degree of toe-in. The sound seems very true to the recording quality: well recorded albums sound excellent and poorly recorded ones do not. I had thought the cabinets were singing along a bit but in fact there's very little vibration coming from them. Perhaps this is a characteristic of cube cabinets.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Simon Hickie
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Joined: Mon Feb 27, 2017 1:47 pm
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Fri Dec 29, 2017 8:10 pm

More extended listening has revealed a slightly recessed midrange with a lack of body, especially on vocals. Swapping a pair of pre-amp valves from Psvanes to Mullards seems to have done the trick and also added a little more depth to the imaging too.

I'm beginning to think that those who say it's not possible for semi-omnis to image well either have never heard a well set up system or don't want to admit that they might possibly image as well as P&S speakers.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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Dr Bunsen Honeydew
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Re: Allison 6 Refurb.

Unread post by Dr Bunsen Honeydew » Fri Dec 29, 2017 8:29 pm

Clutching at straws in the face of reality, there is a lot of it in this hobby. Mostly because of all the ego invested in previous *expert* comment. People should have open minds and accept they could be wrong, the proof is in the pudding, but ego / pride and the need for self worth is a BIG lump of stupidity to overcome.

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