Benz Micro LP Ebony

well if it helps the sales of that phonostage as well as those horn thingys you have increase...then yes it was a figment of my imagination NOT!:D
 
'Matilda' from Hillaire Belloc's 'Cautionary Verses' ( for forum posters) Are you back?
 
I'm back in blighty for a month then back to crete in October. So when are you going to invite me to have a listen to the new speakers?
 
Quote P RansonThis sounds like nonsense.

what part of it sounds like nonsense? The filter stage between 2 gain stages or the fact that trichord etc use the technique?

I think the actual schematic originally came out of a Burr Brown application note for one of their ICs. Since then Michell, Trichord, TE and a whole load of them have been using it.

Doesn't MM require a gain of approx 40dB? and MC between 55 and 70dB depending on the MCs output.
 
RIAA puts 20kHz 40dB lower than 20Hz. So a fully passive eq has to amplify 20kHz 40dB more than eventually required. 40dB is 100times. With opamps this really seriously compromises the overload margin and in the real world scratches and clicks will cause unpleasant effects due to overload. So I doubt that a real world manufacturer would implement this.

It's quite common to put active bass eq around one gain stage and then passive treble cut before a second. OTOH I think the app note circuit in http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1154,C1009,C1026,P1293 has been used by some well regarded products. Fully active EQ FWIW.

Paul
 
Yes, I understand the math as I have built enough of them over the years. Page 12 of the LT1115 app sheet shows the schematic which Trichord, TE, Michell, Lehmann and many others use. This is a basic copy of the Burr Brown circuit and the filter section has been talked about by the great Walt Jung. It really is a cheap method but you can get around some of the basic problems easily. In terms of audio quality.... I'm not a fan.

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1026,P1293,D1612

This is where you'll find the original (I think)
http://focus.ti.com/lit/ds/symlink/opa606.pdf

It's the last circuit which uses a fully passive RIAA.

Hybrid filter circuits on the other hand are much harder to implement for all gains. Whest, Neve and Boulder do it because they have designed their own discrete circuits. But the component count is much much more which is why most manufacturers use ICs.

ICs are generally used to cut down costs. If it were about audio quality then all the BIG high-end stuff would use AD797 and LT1028s or AD825s, but they don't.
 
Paul. ( I know this thread has gone off topic a tad)

Read the tech sheet for the Lehmann Black Cube.

http://www.lehmannaudio.de/download/info/pdf_screen/EN_black_cube_statement_screen.pdf

The passive eq is the same one. Yes it is that easy to do it. I built my first passive stage in 1982. Using 2N4401s and 5534 in the input section - then fully passive - then a NE5534 and 550/560 pair for current output. Back then I managed to get the curve to within +/- 0.4dB at 63dB level 20hz-20Khz.

After you do many of these things you soon realise that the curve accuracy makes up about 4% of the audio quality. Even getting it down to +/-0.15dB at my 63dB made no difference. What makes the difference is when you go discrete and use active RIAA for part of it.

Anyway... the Benz Ebony is great Devil :D
 
Tom evens uses lt1028 and ad797 - plenty of others use ad825. The ad8065 is even better ;)
 
Ever listened to a Boulder 993 module compared to a 8065? or even simpler.... listen to an API channel strip with all the discrete opamps changed over for ICs.

When you get into the bigger league it's all discrete.
 
I don't doubt discrete is better - I refuse to have any opamp in my signal path - however a lot of high end kit does use them.
 
LCR is very difficult to do at any reasonable price. I know a couple of manufacturers who have tried but the cost has spiraled. The results are supposed to be fantastic. Op amp phonostages can be very good in MM stages. I like the firestone audio Korora phonostage. In MM mode it is one of the best I have heard. In MC mode it's good but I would pay the extra for an LCR or suchlike.

Another way of doing it is to use a MM phonostage with a decent step up transformer. The only problem with that any unwanted noise is amplified. So careful matching is needed.

If I were to buy a phonostage now i would buy an FM acoustics 122 or 222 phonostage.
 

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