SP 10

[Ali Tait]

Finally have my SP 10 playing tunes. Been a journey but it’s been worth it. It’s in it’s Panzerholz plinth and I finished setting up my new Reed 3P 12” arm this morning with an Empire EDR9. Tenuto mat to finish it off. Sounds gorgeous.


https://i.imgur.com/0oW5cSv.jpeg

[Barry]

Handsome looking vinyl spinner. Well done!

[Ali Tait]

Thanks Barry. It's been driving me bananas the last couple of days chasing a hum problem, but I finally sorted it this morning. I hate chasing hum down lol. Still, it's all been worth it. Read a lot of good things online about Empire carts, now I hear why.

[Macca]

Fantastic - is it a 12 inch arm?

[Ali Tait]

Yeah, Macassar Ebony. I always thought the 774 was a good arm but that sounds broken next to this.

[Pigmy Pony]

Thing of beauty Ali. Love that arm, I want one!

Big question is, will it be making an appearance at the next NEBO? I know the SL7 will be a hard act to follow :D

[Ali Tait]

LOL, no don't think so, all my gear's in my man cave in the loft now. Much easier to bring the SL7 again. :D

[Ali Tait]

I've recappped it and it seems to behave itself now.

[Andy831]

That's a lovely looking and no doubt sounding turntable Ali, great work :clapclapclap:

[Ali Tait]

Thanks, yes sounding great.

[Pigmy Pony]

How much of a contribution to the sound quality to you think the 12" option makes over say, a 9" one? The arm on my t/t is 12" (though not in the same league as yours), and while I have no complaints, I've never made a comparison. I read somewhere that a longer arm wand can potentially bring issues elsewhere.

[Ali Tait]

Yes have read the same. Hard to say, though it’s definitely on another level compared to the 774, good as that is. The plinth was made to take a Terminator arm, so the arm board is too far from the spindle for 9” arms, so had to go for a 12”.

I did fit the 774, but had to go with Ken Wynn’s geometry as the standard P to S measurement put the arm base off the arm board. Even using Ken’s geometry I had to use one of the armboard fixing holes for the arm base.

[Macca]

Originally longer arms were deployed for playing 16'' transcription discs intended for broadcast.

You will get lower tracking distortion from a longer arm - but it may also have higher mass, less rigidity, more inertia, more resonance. Which all create problems. So it depends on how it's constructed as to whether the trade-off is worth it. For a good one it probably is.

That's my understanding, anyway.

[Ali Tait]

Yep sounds right. Effective mass on this arm with the Ebony wand is 18g, so more or less in the middle. Resonance with the high compliance EDR9 is 6hz, supposedly out of the ideal range, but it sounds great.

[Barry]

6Hz may be on the low side, meaning the arm/deck assembly could be troubled by footballs, but if the assembly is mounted properly, say on a wall-mounted shelf or platform, you should not experience any problems.

Alternative decoupling mechanism may also work. You just have to "suck it and see".

[Ali Tait]

Seems to be fine so far Barry. It’s not wall mounted, but the plinth is pretty heavy so no issues so far with footfall.

[Qwin]

That's a great find Ali, lovely piece of kit.

[Ali Tait]

Thanks Ken, it's a brand new arm, got offered it at a really good price from a good friend. Just fitted yesterday an Acutex 312STR. There was a bit of a buzz about these carts a few years ago and I bought one to try, but it never seemed to gel with the 774 so I put it away. A different matter on this arm though, now I get what the fuss was all about. What a great cart!

[Barry]

Acutex is a totally new make of cartridge to me, so I have been reading up about them. They are an induced magnet design (like the ADC range of cartridges), but what really intrigued me was reference to "triple magnets". By that, I presume the cartridge uses three coils in its generator. So I wonder if it employs a 'sum and difference' coil configuration, similar to that used in the Decca designs. Without actually looking at the patent specification, this is just a speculation.

Looking at the Lenco Heaven forum site, a user there mentions that the clearance between the underside of the cartridge body and the record surface is very small; again similar to that of Deccas.

I have also calculated the low frequency resonance when fitted into your Reed tonearm. Making some reasonable assumptions, I calculate the resonant frequency to lie in the range 4.7 - 5.4Hz. This is very low, but as with your previous cartridge, the cartridge-arm combination having a resonant frequency of 6Hz, your deck, arm and cartridge hopefully will also be free from disturbance by footballs.

[Ali Tait]

There’s a lot of speculation that the compliance of these carts is a lot lower than originally stated, fueled by the fact that Acutex greatly increased the VTF specs from around 0.75-1.25g to 1.5-2.5g. VTF figures like that don’t square with the originally quoted compliance.

I’ve read those threads- the chap with the low riding cart I think had suspension problems- mine rides much higher, even at the 2g VTF I’m currently running at.

I suspect you’re right on the similarity to Deccas- there’s an immediacy to the sound that’s akin to the Deccas I’ve heard.

[Barry]

If you look at the data sheet for the Acutex 312 it quotes a dynamic compliance of 24cu at 100Hz. To adjust this figure to one appropriate to a frequency ~10Hz, the compliance needs to be increased by a factor of 1.5 - 2.0 (depending on the actual cartridge): thus a figure of 36 - 48cu.

These values are indeed high, but are typical for induced magnet cartridges, such as the ADC range, where there is no magnet mass to be moved. For the ADC cartridges the VTFs are typically < 1.5g.

I would agree that there is some variation and confusion concerning the actual compliance of the Acutex range. This might be due to current replacement stylii having a lower compliance to NOS stylii.

[Ali Tait]

But it was Acutex themselves that revised the VTF figures- I’d guess this was prior to any replacement stylus being available from anyone but Acutex. The one I’m using now and the other coming are both NOS so all original.

I can’t see them doing this for any other reason than they came to the realisation that their compliance figures were wrong?

They didn’t just do it with the 312, but all their STR carts as far as I’m aware, which would seem to point to an error in the original calculations.

[Ali Tait]

Here's a pic of the ride height at 2g-

https://i.imgur.com/vAgBBst.jpeg

[Ali Tait]

As far as I'm aware, Acutex were just a reseller, the carts were made in Japan.

[Macca]

I read somewhere that almost all cartridges are made either by Audio Technica or Nagaoka. I don't know how true that is.

[Barry]

Here's a pic of the ride height at 2g-

https://i.imgur.com/vAgBBst.jpeg

Your cartridge is the later version of the Acutex. The original version had a 'squarer' body like most of the cartridges of the '60s.

You can see what the original body shape looks like if you type Acutex 312 into eBay or Vinyl Engine.

What does the data sheet for your cartridge state about the compliance? Like you I'm curious, and puzzled about the change of specification. :scratch:

[Ali Tait]

Yes it's a strange one, never heard of similar with other brands. Yes I'm aware of the box shaped earlier models- confusingly Acutex used the same model names for the long nose versions. Apparently the best of all is the 320, but they are unobtainium now. I have the leaflet that came with the cart Barry, I'll post it up.

[Ali Tait]

Here's where it gets even more confusing. You can see on the photo all the specs for the 3xx range- note they've already revised the VTF figures. But look at the specs for the 320, a compliance figure of 42, yet they're still quoting a VTF range of 1.5 - 2.3g. Can't be correct surely?

https://i.imgur.com/XFBgHv0.jpeg

[Barry]

Thanks for that Ali.

I can only speculate that there was complete redesign of the 3xx series. I agree the cartridges are/were made in Japan, and not in Italy; the Italian company simply being importers and the European agents. It is thus possible the specification data sheet was not fully updated for the new design. Note the frequency for which the compliance figures are measured is not mentioned.

But in the end, all that matters is that you are more than happy with the performance of your cartridge in your arm. :)

[Ali Tait]

Yes that's a good point, the Japanese manufacturers tended to measure at 100hz didn't they?

I've just tried the HiFi News test record, arm resonance is around 15hz, which again doesn't square with the compliance lol.

Yes more than happy, this cart is as good or better than anything I've used previously, including my Benz Gullwing. Given I think I paid £50 for this cart originally, it's unbeatable VFM when you think the Gullwing is 50x the price!

[Barry]

If we take 15Hz as the measured resonant frequency and back calculate, we derive a compliance of 4.7cu. This is about a fifth of the published figure, but is more comensurate with a VTF of 2g.

[Ali Tait]

Yes that would make more sense. How could they have gotten it so wrong?