The Rohde & Schwarz EU-6201 tuner was made for German Ultrakurzwellen (ultra short waves or FM) Broadcast Network. The idea was to have a chain of wide-bandwidth composite signal receivers that feed re-transmitters. I made an attempt to accommodate EU-6201 for my tuner needs. The result is generally positive but not ecstatic. I very much in love what Sansui TU-X1 does and my primary objective were to see if the EU-6201 will be able to compete or exceed the results of the TU-X1.

The Rohde & Schwarz EU-6201 has no MPX decoder on board and outputs wide-bandwidth composite mono signals of the multiplex composite low-passed at 63kHz. After exploring the external MPX decoders I decided to use accommodate one of my Sansui TU-X1 just for stereo decoding functionality.  In the picture below the EU-6201 feeds the Sansui TU-X1 on the right.  The TU-X1 has IM stage disconnected form own the MPX decoder and out stages. The TU-X1s auto-muting circuitry is defeated and stereo engaging circuitry on TU-X1 is made to be active. The Sansui TU-X1 at the top shelf is a “default” TU-X1. Both TU-X1 and EU-6201 + TU-X1 made to output very identical signal level and they drive juts different inputs of Placette active. So to see the different between the tuners is very simple…

A few words about the Rohde & Schwarz EU-6201. It made more then wonderfully. I will not talk about it – take a look yourself:

http://www.goodsoundclub.com/Site_images/Rohde&Schwarz/

Still, it is highly possible that EU-6201 is not made optimum for what I need to get out it. The automated stereo recognition options is not necessary in there for my needs, the very powerful high-gain output stage not necessary for my needs as well, the very sophisticated low-pass filtering options are no good for me as well. So, I ordered the schematics of EU-6201 and I am sure Dima will find a way to optimize the operation for my need. UHF is Dima’s originals trade and he very much knows what and how to do with tuners. Will see where it would lead me…

As the default EU-6201 driven into TU-X1’s stereo decoder/output stage is very comparative to defeat Sansui TU-X1 I turn of sound, in fact the sound of those tow tuners are remarkably identical. This bring to attention the question: when we are not taking about tuner reception but sound quality then do we really talk about juts the sound of the stereo decoders and out stages?

Anyhow, the EU-6201 and TU-X1 have the same decoder/output and they sound the same. There is a VERY small difference in reproduction of the very lowers notes but the difference is very-very small. The difference is so small that it is lower than the difference between two Dominus cables (depends who assembled the cables in POD). Could the difference be neglected?  Hm… I do not know at this point. I think that the difference might be fine-tuned by loading of the EU-6201 out stage. Currently I load the Rohde & Schwarz EU-6201’s wide-bandwidth out (better sounding then filtered) to 900R (10.000R and 1000R voltage deviser before Sansui decoder).  Perhaps lowering it  higher or lower I might altering the minute  satellites of the lower bass but I did not play with it as I ultimately would like do not used the  Rohde & Schwarz’s output stage at all…

Well, if there is no big deference if any deference at all in Sound of the Sansui TU-X1 vs. EU-6201 +TU-X1 but there is quite a large difference in reception. Sansui TU-X1 has its auto-gain circuit before the second stage’s narrow filer and it make the TU-X1 tend for overload in case of a there is another  strong station within the wide scope of the first filer. The Rohde & Schwarz is much more intelligent in this circumstance and it is more immuned to overload. It has better reception for far stations and better noise; still it might derive from the Rohde & Schwarz’s ability to better filter stations.  It hard to say anything without seeing the schematics…

Still, if to use the antenna attenuator and fine-tune the antenna on Sansui TU-X1 for each station (it is what I do anyhow) then the Sansui TU-X1 delivers identical result to EU-6201. Only for very far-located stations or in the conditions of heavy multipath Rohde & Schwarz EU-6201 succeed Sansui. Sansui might resist in this condition if I switch Sansui in “Narrow Mode” but then Sansui loosing its glorious Sound quality.

So, the Rohde & Schwarz EU-6201 is a good tuner. It less convenient to use then Sansui TU-X1 but in its default version it might have some potentials. Let see what Dima would be able to propose to do with it after he overview the EU-6201’s schematics. Theoretically if to get rid from Rohde & Schwarz EU-6201 whatever is not necessary in there and then custom-build inside the Schwarz’s chassis the proven good sounding Sansui’s HA11223W-based PLL multiplex decoder then it might be interesting. The Rohde & Schwarz EU-6201 has two output channels and it has two separate output amplifiers that drive each output separately (!!!). The amps (you can see one of them on the picture):

http://www.goodsoundclub.com/Site_images\Rohde&Schwarz\DSC_3160.JPG

…are made as plug in card in the EU-6201’s motherboard.  The connectors on the card have input signal, access to output signal and power. So , why instead of the high-gains out stage (it dose around 10V in output – I dove with it my entire Macondo) to make a plug-in card that would have a decoder and a good quality 2V output buffer?  Well, let see how it all tune out in future.

I set up one of my TU-X1 to work from own front end and from Schwarz via high quality relay. It very convenient – push a button and the front-end switched. Everything is well shielded, there are no noises and everything is very nice. What however surprised me is that the cable between the Schwarz and Sansui out is very auditable.  Hey, does anybody sell a single Dominus cable?

I wonder: the cable cares analog signal up to 60kHz. Is any special topology would be more suitable for this cable? Perhaps I need to use the instrumental type coax cable? I never before used them for sound. Are any coax better then other? I have no knowledge about those cables...

After learning about the Schwarz’s circuit Dima declared that it will be very simple to build into the unit a good quietly multiplex decoder as the plug in modules as a substitute to the original modules. This will change nothing in the Schwarz but the unit will output a fully stereo signal.

Now I am thinking about the design requirements. The multiplex after the Schwarz’s 63K filter will go to PLL decoding around HA11223W decoder. It is absolute chip but I have bought some of them. The HA11223W is used in TU-1X and considering the sound I am getting from this Sansui I have no doubts that this decoder will do fine. After stereo extracted it shell be de-emphasised. In US the de-emphasis is 75mS, starting from ~450Hz and spreading to 15kH at + 16.5dB. The RIAA corrector anyone?  I think to use Sowter’s indictors for de-emphasis instead of the standard RC filters – it shell be interesting… Then I would need a buffer, probably IC buffer. I have no experience with sound of different op-apms but on recommendation of my friends I would most likely go for AD797, if anything else is more advisable then let me know.

It might be an interesting to see if that decoder will do better then the stock TU-1X. Anyhow, it will be fun to have the default Rohde & Schwarz EU-6201 operating in full stereo. If anyone have done it or consider your Schwarz conversed to stereo then let me know.

I do not know which core and wire materials I shell need, I need to consult with my transformer people for that. As the starting point I plan to use that:

http://www.sowter.co.uk/acatalog/EQ_INDUCTORS.html

It might be good as is of I might order some custom coils with exotic cores, perhaps amorphous, I do not know at this point. I have very little experience with line-level low pass filters with coils. It is possible that the RC will do fine as well because the capacitance will be shunting the signal not bypassing the signal as it would be in high-pass applications. The curve is know:

http://www.goodsoundclub.com/PDF/FMDeemphasis.pdf

 and it shell not be hard to implement.

Well, I still think the coils are a very cool idea, for a number of reasons; but if those coils are spec'd no tighter than 5%, should one also have a way to trim this circuit?

Might be a good idea no matter how they are spec'd...

Sure, parallel/shunt is better, but I can still hear differences between my lo-pass caps, and I still think the best cap is someone else's.

OTOH, coils can be FUN!

Best regards,
Paul S


*   with appologies to The Beatles...

The precision of those inductors is very much irrelevant – it would be easy to fine-tine the filter with the value of the resistor. There is a bigger fish to fry – the benefits of LR filter.

If we are taking about high-pass filter then there are no questions that a series cap is way inferior to RL filter. I tested it a LOT on the Melquiades’ MF channel. However, in case of low-pass the picture is not so clear and I did consider it in Melquiades’ bass channel.

We have two options: a cap to ground vs. a series coil. In case the series inductor the used or passed signal flows across the turn of inductor, so we are taking about a few dozen feet of wire. I do not mention all possible alinearity of inductor. Do not forget that it is a series devise. In case of RC filter we have a cap to ground. Well, we presume that a caps are bad because the electro-mechanic problems with dialectic (or whatever) but, there is one but. In our case of low-pass filter the filer-transparent or passed signal flows across a resistor to load. What flows via a cap is the filtered signal that is getting shorted to ground. So, it is hypothetically possible that a CR filter would not be damaging in low-pass context.

I do not know the answer at this point. I was trying to test it in Melquiades’ bass channel but the inductor was large in there and I was not able to shield it properly. In the case of decoder the inductor will be much smaller and the concept would be essay to trail.

Romy the Cat wrote:

As now the Rohde & Schwarz + T-85 sound just wonderful and I would not look for other Multiplex Decoders with exception of a future idea to built one even better (with L de-emphasize)  INSEDE of the Rohde & Schwarz. So, effectively so far the Decoder project is over.  Probably the most reasonable question would be to ask how the Rohde & Schwarz + T-85 Decoder sound in relation to TU-1X. I have the judgment and it is much unexpected judgment at least to me. I will post it later on in the Rohde & Schwarz’s thread along with some commentaries.

People who read my site regularly know that one of the fundamental rules for understanding my audio rational is accepting the following postulate:

http://www.romythecat.com/Forums/ShowPost.aspx?PostID=432

I have to admit the in my tries of adopting the Rohde & Schwarz were not the subject of my above linked rules of audio self-navigations. I very much pleased, beyond expectations of what the Sansui TU-1X does (not the “experimental one” but the very original one converted of direct coupled output - no other changes are made there). My level of comfort with my original TU-1X is so great that I not what (or afraid) to touch and have no desire to seek better Sound. So, the Rohde & Schwarz ides was pure fishing to see if anything else is possible by virtue of a classic analog tuner design. The Multiples decoder was a big obstacle but it was resolved.

http://www.romythecat.com/GetPost.aspx?PostID=7675

So, was the Rohde & Schwarz able to push the Sansui TU-1X’s Sound further?  Well, it was not able to. The key in the answer is that in case of respectfully-proper operating conditions the Rohde & Schwarz and Sansui system threw absolutely identical sonic results. What I realized it was in a way disappointed but then I spoke with Dima and he pitched to me a very interesting observation that I found fascinating. He said:”

Romy, look, you have two absolutely different top-flying tuners make with very high objectives. They were made by very different people with very different design cultures. They use different parts, different topology and different architecture. However, they both end up with the same resulting sound. So, does it mean that the result that you are getting it is what is basically possible to get out of FM by use of sensible means?”

I was thinking what Dima proposed and I feel that makes a lot of sense….

Well, I have no addenda what tuner is “better” my Sansui TU-1X of the Rohde & Schwarz +T85’s decoder, I have no need to sell ether of them and having two A/D processors that I trust (Lavry 122 and pacific) I might as well use both. I might set up one for listening and one for recording only – I can do whatever I want. There is a difference between Sansui and Rohde’s use & Schwarz’s use and I would like to take about it. However, the major underling fact of all differences shell be the knowledge that both R&S and Sansui, if be aware and to serve their own idiosyncrasies deliver absolutely identical Sound. Also, my Sansui is perfectly calibrated and aligned. My Rohde & Schwarz is not aligned and my Schwarz’s Multiplex Decoder (T-85) is calibrated by me (which might not mean a lot)

1)  Sansui need external, manual, very precise, antenna signal dial-in. 1-2dB of wrong signal strength on the Sansui’s front end send Sansui’s into FM noise. The R&S is much more immune from it and it basically would like to have as much antenna signal as you can feed it.

2)  R&S is pain in ass to tune in case of frequent station change. The Schwarz take time to stabilize the station, sometimes it needs 2-3 adjustment within a fist hour after the station is tuned. However, as the Schwarz is tuned and the tuner is in it’s cruise temperature and mechanic state then the Schwarz’s holds the frequency very fine, controlling and tuning the station with less than 5kHz(!!!) precession. Sansui is much more forgiving and much less precise then that.

3)  the Rohde & Schwarz has better selectively then Sansui in Wide Mode (I never use narrow Sansui’s’ mode as it sound not as good) but playing with attenuator it is possible to make Sansui to sound very similar to Schwarz. The Rohde & Schwarz with it’s one signal mode does have advantage in DXing and reception of far stations near a powerful neighboring stations however, I do not recognize is as “Sound” but  rather as a “receptions”. The advantage is there but overly huge. The Yamaha T-85 is far better DX machine then both Rohde & Schwarz and Sansui.

4)  Sansui has tone generator – very useful tool that permit to calibrate A/D processor – the equality of the R+L channels sensitively - I wish my stations broadcast always the channels equally.

5)  Rohde & Schwarz need to run for a few hours to become like a measurement machine. When it “cold” it “flies” here and there. Sansui is good after a few minutes.

6)  Sansui scale is more predictable and more intuitive then Rohde & Schwarz. The Schwarz’s ultra-precisions scale is more gimmicky and not good for play-and-play tuning

7)   Now, I can tell that internal Multiplex Decoder is a pint in ass. The decoder should be in the tuner and the output shell drive 2 loads with no impact to impedance sinking. So far the Rohde & Schwarz is two chassis tuner…. From a different perspective the Sansui is enormously large. Put Multiplex into Rohde & Schwarz or take AM section out of Sansui and make it smaller.

8)  Rohde & Schwarz and Sansui have slightly different character of noise in case they vaguely out of optimum operation condition. When Schwarz starve for signal then it develops a continuing MF hiss. When Sansui starve or overload with signal then it develops none-continuing choking, pinging time of distortions with some MF hiss.

This is all for now. I will be killing both tuners and perhaps will be more able to detect the advantage of a specific tuner at a given station of my given antenna configuration. I might post some recording from the R&S +T85 tandem if any interesting recording come along and if I use the Schwarz for recording. As time goes buy I discover more and more new ways to make my FM recordings better…

Romy the Cat wrote:

5) Rohde & Schwarz need to run for a few hours to become like a measurement machine. When it “cold” it “flies” here and there. Sansui is good after a few minutes. 6) Sansui scale is more predictable and more intuitive then Rohde & Schwarz. The Schwarz’s ultra-precisions scale is more gimmicky and not good for play-and-play tuning

I do some very interesting experiments with Rohde & Schwarz tuner. Dima and I have discovered a way to use the Schwarz without the wide bandwidth amplifier, driving the Multiplex Decoder from the Schwarz’s preamps. Basically we put two stages with all it caps cap out of services - a very nice intellectual improvement. Doing it I discover that Rohde & Schwarz is heavy on use right in signal pass he Tantalum Caps. They are 16V 10uF-220uf. I was looking at them and desired to replace them with non-polar Nichicon Muse - the tested good cap. Well, I would like to reports that it got substantially better but am not sure. The Muse need some time to open up but since I know them very well and can predict their sound I still am not convinced that muse will my cap of chose.

Thinking about it I was educated myself about the Tantalum Caps. It turned out that there are Tantalum Caps, that are not partially too exiting and there are WET Tantalum Caps. The Wet Tantalum Caps are very different animals. They expensive like hell but it is very possible that is they are probably used (they must be DC biased) then they do just fine:

http://www.itiomar.it/pubblica/Telecomunicaz/lezioni/3_anno/Cap-Ta-2.pdf

http://www.vishay.com/capacitors/tantalum/wet-tantalum/

Rohde & Schwarz used both dry and wet caps I replaced them all to wet. What attracts me in the sound of the wet caps is notable higher transient performance… and substantially less foggy bass.  Well, perhaps I need to let the   Nichicon Muse to settle down and then to see what happen. Anyhow, my initial prejudices that those Tantalum Spragues from 70’s should be replaced on spot might not be too reasonable. Let see what happen…

Since FM long has been my primary at the most enjoyable audio source I decided to push the envelope a little further. The Rohde & Schwarz tuner bind via wide-bandwidth output with modified Yamaha T-85 MPX decoder sounds identical to Sansui TU-X1. That is an accomplishment itself BUT the Schwarz has more sophisticated font end, twice faster intermediate frequency stage and way fancier filtration. It is not to mention that broadcast level Schwarz built 100 times better then consumer-targeted Sansui. So, why Schwarz’s advance do no manifest themselves sonically? Schwarz is slightly better in varicose reception settings but not a lot if to tune the signal attention for Sansui very precisely.

Sansui is very fine aligned and tuned with actual measured sensitively of 0.8uv, stereo distortions in wide range of 0.022% and separation of 56dB. The Rohde & Schwarz tuner is “as is” – I have no knowledge about its state. I made a number of calls for the different tuners shop – not one worked with Rohde & Schwarz EU-6201. I spoke with Rohde & Schwarz repair center in US – they told me that they do not support this model anymore in US. I spoke with Minchin guys and they told me the same. Well, with lock of ability to objectively evaluate the sate of my Schwarz alignment I went hard way to learn: I bought another Rohde & Schwarz EU-6201. That one come directly from Germany and the prices was quite attractive.

The new Schwarz was exactly what I was looking for – with all being equal it has 7dB more sensitivity then my old Schwarz. That is huge itself and that made Schwarz way more sophisticated then Sansui TU-X1 in term of reception. The DXing with new Schwarz is truly superb, the selectively is beyond compare to Sansui TU-X1 and the ability of the Schwarz to care overload is just wonderful – Sansui dives into noise in DXing with extra 2dB-3dB, the Schwarz cares +15dB with no effect to sound at all. Well, I still do not know if my new Schwarz is properly aligned but it itself clearly proves there is a room in Schwarz for alignment improvement. If the alignment improvements in Sansui are not truly effective as the Sansui easily get overloaded then in the Schwarz is totally different story and ease uV is very much usable in Schwarz’s reception. So, the concussion is that my Rohde & Schwarz need to be very precisely and very artistically aligned, preferable right along with the new MPX decoder that Dima and I am planning to bud.

Here is a good Rohde & Schwarz EU-6201 illustration. This is a station not truly DX but a station that is in very difficult reception environment. I never was able to get it clear from my location. Even the DX champion Yamaha T-85 in its ultra narrow more had it with quite unpleasant noise (not to mention that T-85 sound more or less OK only in super wide mode). Sansui have it with some noise and the most unpleasant with some braking up. It was very said as this station does BSO live broadcasts…

Now, the new Schwarz – no pre- filtration, not attenuation, one range, no tricks. The tuner doe wonderfully I am applauded the recording. It was recorded in 88/24 via Schwarz, T-85 decoder and then into Lavry Gold AD. The uploaded file is down conversion to 44/24 file – so some transients got eaten. The Trojans at Carthage of Berlioz's epic opera Les troyens James Levine conducts the Boston Symphony Orchestra and the Tanglewood Festival Chorus in a LIVE broadcast from in Lenox, Mass. You will see that sound is defused and not praised but it is from the Koussevitzky Music Shed at Tanglewood – open air performance. If you were then you know that it is how the Koussevitzky Music Shed sounds…

http://www.mediafire.com/?0rjmvgyjdhh

You will see some minor noise from Schwarz as well but at very low level. Also I did not deal a lot with this station and I do not know what noise normally their equipment has. Anyhow, regarding all technicalities I hope you will feel how different LIVE broadcasts are from any pre-caned crap that industry realizes on CDs.

The Cat

Romy the Cat wrote:

I do some very interesting experiments with Rohde & Schwarz tuner. Dima and I have discovered a way to use the Schwarz without the wide bandwidth amplifier, driving the Multiplex Decoder from the Schwarz’s preamps. Basically we put two stages with all it caps cap out of services - a very nice intellectual improvement. Doing it I discover that Rohde & Schwarz is heavy on use right in signal pass he Tantalum Caps. They are 16V 10uF-220uf. I was looking at them and desired to replace them with non-polar Nichicon Muse - the tested good cap. Well, I would like to reports that it got substantially better but am not sure. The Muse need some time to open up but since I know them very well and can predict their sound I still am not convinced that muse will my cap of chose. Thinking about it I was educated myself about the Tantalum Caps. It turned out that there are Tantalum Caps, that are not partially too exiting and there are WET Tantalum Caps. The Wet Tantalum Caps are very different animals. They expensive like hell but it is very possible that is they are probably used (they must be DC biased) then they do just fine: http://www.itiomar.it/pubblica/Telecomunicaz/lezioni/3_anno/Cap-Ta-2.pdf http://www.vishay.com/capacitors/tantalum/wet-tantalum/ Rohde & Schwarz used both dry and wet caps I replaced them all to wet. What attract me in the sound of the wet caps is notable higher transient performance… and substantially less foggy bass.  Well, perhaps I need to let the   Nichicon Muse to settle down and then to see what happen. Anyhow, my initial prejudices that those Tantalum Spragues from 70’s should be replaced on spot might not be too reasonable. Let see what happen… The Cat

Well the whole saga with the Wet Tantalum Caps turned out to be exiting but disappointing. I bought the 138D Wet Caps:

http://www.vishay.com/docs/40025/138d.pdf

….and tried them in the Schwarz’s critical signal pass. I mean it is not bypass or PS but right in series with signal as the coupling caps. The Schwarz’s used originally the 150D the Dry Tantalum Caps, those were replaced with bipolar Nichicon Muse. The MUSE was better, Muse sound like bipolar BG caps that were burned in for 16 years. Anyhow, to make the long story short – the ugly (but expensive like hell) Wet Tantalum Caps left no doubt that they are way more superior then even MUSE, not to mention the dry Tantalum caps.

I do not want to talk about it a lot – this is the Rohde & Schwarz tuner thread and I mention it here juts because the Rohde & Schwarz project let me to discover the wonderful sound of the Wet Tantalum caps. So, why do I call the result disappointing?

The sound of the Wet Tantalum caps is not disappointing – quite in cotasry but I was told by many “experienced” people with whom I consulted before and I heard from them only (with exception of one guy) one answer from them: “as soon you see those Tantalum caps then get rid of them immediately.” Well, this indicated nothing more then there are too many idiots in audio who love to talk confidently about the subjects that have no clue.

Anyhow, the Wet Tantalum Caps stay in my Rohde & Schwarz.

be wrote:

Very interesting "review" thanks. The 150D is possibly not the most relevant comparison, it does not seem to be a high quality product since its ESR values are not even mentionned in the data sheets. Tha T97 series: ( http://www.vishay.com/docs/40092/t97.pdf ) might be even better than the 138D and other wet types, at least its much better data hints at that, but they dont come in as large values as the wet ones.

Tonight I recorded the Live Tanglewood broadcast with all Russian program:

http://www.bso.org/bso/mods/perf_detail.jsp?pid=prod2110030

…  I decided to let the ghost out of bottle and to let the EU-6201 receiver with modified Rohde & Schwarz MSDC MPX decoder to record the second part of the broadcast. I connected Schwarz to Lavry AD122 analog to digital converter. Flipped the Lynx 16 from dual-wire mode to single-wire … here we go… The file is as usually – 88/24, around 90meg (converted to WAV 32-bit before uploading) - make you own judgment.

http://www.mediafire.com/?sharekey=0491b631ff230f14d2db6fb9a8902bda

The BSO was not at thier best but they were reasonably-reliable today. You will see some FM hiss but my Saturday broadcasts, as I previously told, come from “ugly” station.  Still, the Sound is good enough to trash most of the LPs and CDs