BeoGram

Re: Cartridge choices - an independent test

kirkus — Fri, 15 Jul 2011 09:25:37 GMT

Some of these videos are quite interesting; I actually have the ones with Stanley Lipshitz, Richard Small, and A.N. Thiele. AES still wants $15 a piece (and no further discount with the E-Library membership) which IMO is a bit steep.

But I'm very much of the opinion that the 1970s were a time where the mechanical and materials improvements in phono cartridges were advancing rapidly, and the preamp stages were still very conservatively designed. B&O's designs are pretty conventional for the era, using two transistors for the gain with nested active EQ, and then later a third for an output follower. This bears more than a superficial resemblence to the two-section valve circuits from the Mullard preamp designs (themselves influenced by Sallen & Key?), which were designed to be able to use a single ECC83 (12AX7 in the US). Higher-end valve designs (i.e. Mac & Marantz) added a third valve as a follower (one section for each channel), just as B&O did in the mid-1970s with their similar transistor designs, as lower-impedance tape outputs became necessary.

The main flaws with these designs IMO is the fact that they still use circuit impedances similar to their valve ancestors, and suffer from increased noise (bipolar transistors having a lower Vn/En characteristic) and RF suceptibility (bipolars rectify incoming RF quite readily). The RIAA equalisation tends to be more variable as well, as it depends on transistor beta, which is much more variable than a valve's mu. These variabilities are amplified even more by the low open-loop gain of these circuits, and specifically the input capacitor would have had a handy side-effect of reducing the RF vulnerability of the input transistor.

It wasn't until the late-1970s and early-1980s that the design of RIAA phono preamps received widespread attention for redesign - the aforementioned Stanley Lipschitz wrote a famous AES paper in 1978 addressing many of these issues . . . and the contribution of Peter Baxandall through his responses to this paper was (and is) also greatly influential. Phono preamps certainly came a very long way in the 1980s, while the development of phono cartridges plateaued.

Anyway, it's certainly an interesting discussion.

Re: Cartridge choices - an independent test

soundproof — Sun, 10 Jul 2011 03:29:26 GMT

Here's Subir Pramanik on his work for B&O. He developed the SP15 cartridge and actually proposed the tangential arm, which Jensen originally was against.

(Please visit the site to view this media)

Re: Cartridge choices - an independent test

soundproof — Sun, 10 Jul 2011 03:21:54 GMT

Hello kirkus,

I doubt that the loadings used by B&O hung on to the 50/60s practices, particularly for the cartridges we are considering here. During the transition from multi-eq loadings to the generally accepted RIAA-standard, turntables/amplifiers had to accommodate a variety of EQ-standards. Many mono-recordings were using curves that differed significantly from RIAA, for instance.

But the Beogram 4000 came at a time when RIAA was well established, and when HiFi had begun moving away from giving users control of different curves. Soundsmith actually "beta-tested" different cartridges among selected customers, having given them different voicings, and the preference stated was for the brighter voicing.
As I theorize in my review, this could be because customers' vinyl had lost some treble, and the brighter voicing reintroduced it, or else because customers wanted a sound that more closely matched what they get from CDs.

A fun listening paradox is involved here. As you state, LPs became capable of reproducing better treble during the 60s/70s - but customers actually turned away from the best treble resolution available: DMM. They judged it harsh and bright, preferring the actually more muddled sound from pre-DMM vinyl reproduction. A conundrum for the conductors and performers, who found that DMM resulted in better treble than was available from any other record or tape method.

The classical music industry embraced DMM, but customers were skeptical, and as one by then couldn't adjust EQ-curves with any timing-specificity you were reduced to coarse treble/bass adjustments to get it to your liking. I have a complete Wagner Ring on Teldec DMM, an absolutely fantastic reproduction on vinyl, and it bombed when it was released.
Ironically, DMM-mastering is now all the vogue again in vinyl, and delivering even better results because of computer control in cutting.

Why did my Soundsmith SMMC20/CL+ cartridge sound fatiguing when reproducing Linn's Messiah? Well, the vinyl is very well made and has ample treble information. The brighter voicing of the cartridge overemphasized this, most likely.

I'm presently planning my next listening room, where I will have one of these. It gives me complete control of the EQ-curves and loadings, in an analogue signal chain. And everything comes full circle!

http://www.emt-studiotechnik.de/JPA66%20E.htm

Re: Cartridge choices - an independent test

kirkus — Sat, 09 Jul 2011 17:35:13 GMT

Hi Peter,

Thanks for the informative research and post, very interesting.

Just wondering, have you ever tried changing the electrical loading for the cartridge a bit? Most B&O phono inputs load the cartridge with 160pF and 47K Ohms, and I personally think this is for reasons of tradition . . . it gives a bit more pronounced high-frequency and ultrasonic peak from the cartridge's self-inductance, and was more necessary in the 1950's and 1960's with the cartridges and recordings of the era.

While cartridge technology increased greatly in the 1970s with regards to high-frequency performance, for some reason the preamp loading practices never changed, and IMO this leads to an unnatural accentuation of high frequencies and surface noise. It may be that the Soundsmith cartridges have a slightly higher inductance, and the 160pF load really amplifies the issue.

My preference with vintage B&O cartridges (I'm currently using a 20CL) and Soundsmith alike is loaded with only the cable capacitance (no loading cap on the preamp) and a 75K or 100K terminating resistor instead of 47K. I think it makes them all sound much cleaner and smoother (though not necessarily "duller") on the top end.

Re: Cartridge choices - an independent test

Agent00soul — Sat, 13 Nov 2010 14:08:51 GMT

Years ago I used to have a Beogram 4002 with the quadraphonic pickup, I think it was a MMC6000.
While this pickup yielded excellent sound quality, it was extremely sensitive to the quality of the record pressing. Some records that sounded totally OK on another system, sounded awful with this pickup. I returned several records to the store for a replacement but when they played them in the store, they sounded fault-free.
So using pickups designed for CD-4 on normal stereo records is not such a good idea. I now have a Beogram 2000 with a SP-10 and can play the same records without surface noise.

Re: Cartridge choices - an independent test

Doctor — Tue, 26 Oct 2010 13:39:41 GMT

Afraid I have deleted all the files. The SMMC20EN/CL has a pronounced lift compared the the old CL. Sounds more detailed but some might find it a little fatiguing to listen to. All a matter of taste! I prefer the MMC20CL.

Re: Cartridge choices - an independent test

Step1 — Tue, 26 Oct 2010 12:28:52 GMT

DSJR:

The Beogram 4002 has hard rubber "ribs" giving very marginal support to the vinyl records played (easily measured in reviews).

Is this really measurable and how does the contact effect tracking to such extent?

Re: Cartridge choices - an independent test

Step1 — Tue, 26 Oct 2010 12:27:13 GMT

Peter are these recordings still available? I am contemplating sending one of my carts off I would like to hear some comparisons...

Re: Cartridge choices - an independent test

DSJR — Sun, 30 May 2010 16:33:58 GMT

A quick comment on the new 20CL not always tracking as well as the new EN..

The Beogram 4002 has hard rubber "ribs" giving very marginal support to the vinyl records played (easily measured in reviews). This *may* upset the tracking security of the CL model with the fussier tip. Just my thoughts. Adding a thin felt mat such as the Linn one on top of the existing ribs and ensuring the stylus clears the record when lifting off used to gentle the roughness up a bit and the revised VTA (akin to lowering the arm at the pivot on a conventional tonearm) won't do any harm I think.

Having said the above, I must admit to finding my original but little used 20CL rather "distant" in perspective. Tracking of this sample is still excellent despite its age (I don't use it in a Beogram).

Many thanks for posting your results. It's great that these venerable old decks can still be kept going.

Re: Cartridge choices - an independent test

chartz — Mon, 23 Nov 2009 02:46:46 GMT

Hello,

Just to make things a little more confused (!) I went to iTunes and listened to the AAC track. It's a bit brighter than the CD version, but it may be down to the compression scheme. Anyway, my favourite cartridge is n°8 (whatever that is, CD again?), since n°9 is the CD!

I listened to the surface noise too, and the record appears to be very quiet. On my system, even the CD is a bit lacking in bite and dynamics I find, although the saxophone is very nice indeed.

My original MMC20EN (little used, in good condition) sounds like n°1, dynamic with excellent bass but lacking in treble.

Definitely n°8.

Re: Cartridge choices - an independent test

Peter — Sun, 22 Nov 2009 14:39:00 GMT

I think it is the record! So judge the recordings against each other!

Re: Cartridge choices - an independent test

chartz — Sun, 22 Nov 2009 14:28:55 GMT

By the way, I used CD Spin Doctor as well. Perfectly adequate!

Re: Cartridge choices - an independent test

superdario — Sun, 22 Nov 2009 14:14:49 GMT

nothing wrong about your apple g5. maybe it's the software... i use final vinyl with i mic usb adapter from griffin to record high quality .aiff-files. you can easely convert it to .mp3 with lame mp3 converter installed in audacity.

http://www.amazon.de/Griffin-1102-IMIC2-iMic2-USB-Audio-Adapter/dp/B000BVV2IC

http://www.apple.com/downloads/macosx/audio/finalvinyl.html

http://lame.sourceforge.net/

cheers

Re: Cartridge choices - an independent test

Peter — Sun, 22 Nov 2009 13:29:04 GMT

Have redone 9 and added Chartz recording - not as long but clearly different.

Re: Cartridge choices - an independent test

Peter — Sun, 22 Nov 2009 13:21:41 GMT

It is a PowerMac G5 which was supposed to be fairly useful in its day though it is getting on a bit. I wonder if it is the recording I have - sounds much the same through the record player direct to be honest! 9 is a control....