Angle Audio Phono stage

the thin end of the wedge
jkilla
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Re: Angle Audio Phono stage

Post by jkilla » 15 Jan 2013 14:42

Strongly considering buying one of these, is the battery version worth the extra 50 GBP added cost?

Angleaudio
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Re: Angle Audio Phono stage

Post by Angleaudio » 07 Feb 2013 16:52

Angle Audio here..

We will soon be selling our products directly from our own website,

Please 'like' our Facebook page by searching for 'Angle Audio'.. for upcoming news and offers,

Thank you all for your amazing reviews :D =D>

darkmatter
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Re: Angle Audio Phono stage

Post by darkmatter » 28 Mar 2014 22:51

I have contacted Chris as well to see if he can make a higher gain phonostage for use with a passive pre-amp :)

jurma
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Re: Angle Audio Phono stage

Post by jurma » 24 Apr 2015 15:54

Bought this device some months ago. Angle audiophile unit with virtual battery.
I must say that it is totally bad... :cry:
I will not speak here about "cheap alu-box design" and battery life that runs only 6Hrs when plugged into mains! That's not so disappointing as it's sound.
To be accurate in my conclusions I performed measurements using high quiality sweep-tone.
I passed high quality white noise and sweep tone to phono stages from M-Audio ProFire sound card using cable with resistive voltage divider (1/1000) not to overload the phono stage. The phono stage output was immediately captured with the same sound card.
First I measured the sound card loop-back. It is quite flat and we can ignore it for this test.

Then I applied reverse RIAA equalization to it.(using Audacity software equalization plugin preset)
Here is what I've got
http://i48.fastpic.ru/thumb/2015/0424/7 ... 6e673.jpeg
As you can see, Angle device begins to roll off too early and too strong: at 10kHz -3.5bB to RIAA, at 13kHz -3.8bB, at 15kHz -4.4dB, at 17kHz -5.1dB to RIAA, etc.
By the time I have tested 5 different phono stage models with the same set-up (Lehmann Black Cube, Cambridge Audio 651P, Pro-Ject phono box II, Rega Fono MM, Angle) and only Angle has that significant frequency roll off. Others begin to roll off at near 40kHz.

I contacted the seller with this problem but was responded that it's already too late for refund and they can repair it but only if it is out of THEIR specs.
Anyway it's too long way and money to send it here and there from the place I live at my own expense. So I decided to find where is the problem.

It's based on two BB opa1237 amps and passive RIAA circuit between them.
I recalculated RIAA circuit - it was more or less OK, but one capacitor is quite far from calculated. I added +330pF there to both channels.
Then I run the circuit in TI-TINA simulator and discovered the real reason of this early frequency roll-off. Schematics design is totally wrong.
OPA1237 does not work well at that setup. OPA1232 should run much better (I suppose the unit was designed for OPA1232 but they replaced it to 1237 due to price)
I replaced op amps to OPA1232 and made measurements again.
Result: frequency roll-off moved up. But I still had about 1dB less on 20kHz.
I decided to distribute amplification ratio of both cascades more equally(the first was 107 and the second was 10)
And here we are - I have perfect sounding Angle Audiophile unit now! :wink: =D>
It took 5$ on parts and much more time on thinking.
Do you really need to walk all that way yourself? I think no :D :D :D

Rob998
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Re: Angle Audio Phono stage

Post by Rob998 » 25 Apr 2015 21:56

SF's Angle Audio phono stage now lives in my system, and is sounding very nice indeed.

Seems to add a little more clarity than the Project, so in audiophool terms, "A veil has been lifted..." :mrgreen:

Thanks to Chris (SF) for the stage, and thanks to Chris (Angle Audio) for answering some probably very silly questions about his product... =D>

Rob998
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Re: Angle Audio Phono stage

Post by Rob998 » 25 Apr 2015 22:20

Also it doesn't have the worlds brightest blue LED blinding me every time I glance casually at it...

Finger Painter

Re: Angle Audio Phono stage

Post by Finger Painter » 25 Apr 2015 23:09

Glad to hear it went to a good and appreciative home Rob998.

As for the incredibly blinding blue LED, I know exactly what you mean. I missed one for so long it was one of the reasons to buy the Sonneteer :wink:

Cool blue?.......my arse

Rob998
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Re: Angle Audio Phono stage

Post by Rob998 » 25 Apr 2015 23:17

The more I listen, the more I agree with your initial review. Not surprising I suppose, after all I took the exact same upgrade path. It really is a nice upgrade over the Project, which I still think is a good stage, but there is a lot more information being sent through the Angle.

I was thinking of upgrading my speakers due to a perceived lack of bass, but no, I think I 'll hang on a bit...

jurma
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Re: Angle Audio Phono stage

Post by jurma » 26 Apr 2015 09:11

Forgot to post some test results to compare. I'm not speaking about that mystical audiophile 'veil'. Device with that frequency response as Angle Audiopfile MM has undoubtedly lacks of middle heights and upper heights. Having about -3db at 10kHz and -6db at 20kHz is just catastrophic not only for audiophile ears.

Here you are:

Initial Angle Audiopfile MM Virtual Battery unit:
http://i57.fastpic.ru/big/2015/0426/5c/ ... dea15c.png

Redesigned Angle Audiopfile MM Virtual Battery unit.
It has potential to push frequency roll-off even a bit higher. Not as lehmann and rega though. I suppose - up to 35kHz with current schematic design. I just used parts I had at home at the moment:):
http://i58.fastpic.ru/big/2015/0426/1e/ ... 9d051e.png

Lehmann Black Cube Statement:
http://i57.fastpic.ru/big/2015/0426/3e/ ... d4863e.png

Rega Phono MM:
http://i60.fastpic.ru/big/2015/0426/e6/ ... 30eae6.png

Rob998
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Re: Angle Audio Phono stage

Post by Rob998 » 26 Apr 2015 22:39

Well, I'm not going to get into an argument about how it measures, because, i) I don't have the equipment to measure my particular phono stages, and ii) I've heard stuff that measured horrendously, but still sounded superb for whatever reason.

All I'll say is that in my subjective opinion, the Angle Audio stage that I have sounds better to my ears than the Pro-ject it has replaced.

Rob998
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Re: Angle Audio Phono stage

Post by Rob998 » 10 May 2015 21:26

One negative thing I've found out. This thing is highly sensitive to mobile phone and WiFi interference.

If you go to change a record with your phone in your pocket you get that dit dit dit dit noise, and it just happens that in the next room, but less than a metre away from my hifi rack, there is a WiFi connected smart Tv, a PS3 and a Wii, and one of those things must do something over the WiFi every 5 minutes or so, because there is a regular lowish frequency signal that the stage picks up. When music is actually playing you're unlucky to hear it, unless it's a quiet passage, but if you're not playing anything then it's very audible.

Also there's a quiet, low frequency hum that's always there. I've tried every combination of earthing I can possibly manage to no avail. Then I turned off the WiFi....

I'm planning on changing my room around soon so it will be better isolated from all these external interferences, but until then I have put the Phonobox back in the system.

The Angle definitely sounds better in the absence of all the above-mentioned stuff, but the above-mentioned stuff is irritating me, and I'm finding that I'm listening out for it, rather than just listening to the music...