Marek, the next step is to try tube output stage,
could you share simplified scheme of point 3 and 4 ?
3. SRPP -> The Valve Wizard- SRPP
4. diff preamp http://rapidshare.com/files/448854915/ls60_balance.pdf
ofcourse for you should modify circuit for tube you choose.
and one more thing. If you want to connect DAC directly without caps you have to recalculate cathode resistors to compensate DAC DC offset.
4. diff preamp http://rapidshare.com/files/448854915/ls60_balance.pdf
ofcourse for you should modify circuit for tube you choose.
and one more thing. If you want to connect DAC directly without caps you have to recalculate cathode resistors to compensate DAC DC offset.
I am in the interim tried using a step up with 28dB gain. The primary is 1.5R and secondary is 400R, with good results, appreciate some advise if this is safe for longterm usage?
Do you reckon if any of these could be adapted to work with B-II, which would be ideal?
a) 6SN7 SRPP by diyhttp://analogmetric.com/ebay/6SN7%20Preamp%20schematic.JPG
b) ebayer raindrop_hui's SRPP tube output module coupling transformer
Thank you
Do you reckon if any of these could be adapted to work with B-II, which would be ideal?
a) 6SN7 SRPP by diyhttp://analogmetric.com/ebay/6SN7%20Preamp%20schematic.JPG
b) ebayer raindrop_hui's SRPP tube output module coupling transformer
Thank you
Step up trafo you use is ok for long term use.
You should load secondaries with a proper resistance (as low as possible) to allow DAC see low impedance (to put Sabre outputs to work in near current mode).
From my experience step up trafo is not the best choice with Sabre32 chip - it is not typical current out DAC and it seems working better in voltage mode with 1:1 trafo (like Jensen JT-11P-1).
If you plan to use tube output the best choice is leave trafos and put positive DAC output DIRECTLY to tube grid without any capacitor (you should recalculate cathode resistor to compensate Sabre DC offset)
SRPP is good choice but that one form analogmetric is based on 6SN7 tube which has definetely to much gain for voltage mode Sabre and to high output impedance.
You should load secondaries with a proper resistance (as low as possible) to allow DAC see low impedance (to put Sabre outputs to work in near current mode).
From my experience step up trafo is not the best choice with Sabre32 chip - it is not typical current out DAC and it seems working better in voltage mode with 1:1 trafo (like Jensen JT-11P-1).
If you plan to use tube output the best choice is leave trafos and put positive DAC output DIRECTLY to tube grid without any capacitor (you should recalculate cathode resistor to compensate Sabre DC offset)
SRPP is good choice but that one form analogmetric is based on 6SN7 tube which has definetely to much gain for voltage mode Sabre and to high output impedance.
What do you mean by "long term use"?
You should load secondaries with a proper resistance (as low as possible) to allow DAC see low impedance (to put Sabre outputs to work in near current mode).
how did you load the trafo?
Best
Pietro
yes but you said something about "long-term" use which to me is quite strange, can you tell us what did you mean?
Pietro
I'm running a 2:1 trafo and it's working perfectly. I haven't even had the time to fine tune the load for the transformer and it's still kicking *ss.
What I understood is that you need to know the preamp/linestage input impedence in order to match the trafo's load.
I use a Lundhal trafo, so I wrote to Per Lundhal with preamp specs and he gave me the right resistor to load the trafo... it works very good, and I don't undesrtand this "long-term use" thing mentioned previously.
ciao
Pietro
silver rock transformer output stage
This is exactly the configuration I've been seriously considering for my Buffalo IIs, although I haven't pull the trigger on silver rock due to its cost and the lower dynamic range of 9018 chip when voltage mode is used. Did you compare this with any other output stage? Or can you give any comment about sound characteristic of your modded CDP with any high end CDP?
Thanks!
This is exactly the configuration I've been seriously considering for my Buffalo IIs, although I haven't pull the trigger on silver rock due to its cost and the lower dynamic range of 9018 chip when voltage mode is used. Did you compare this with any other output stage? Or can you give any comment about sound characteristic of your modded CDP with any high end CDP?
Thanks!
rdj845, I have only tried B2 with battery-powered Placid & Tridents through an output stage of Audio Consulting Silver Rock transformers and battery-powered LME49600 buffers. My guess is that together with galvanic separation, the well powered and bypassed buffers do the best than can be done with B2 as a voltage source. This output stage has been proved out by Reference Audio Mods across a wide range of modified CDPs. Personally I can only vouch for it in my modified SCD-1, where I directly compared buffered transformers coming directly off the DAC to several approaches using an I/V stage. There is a lot to be said for a very simple, optimally powered circuit coming directly off the DAC chip with a minimum of piece parts to get in the way. It's the best RBCD I've heard, and I do get out to CES, RMAF, Axpona, etc. to hear many commercial alternatives. The buffer is critical to adding dynamics and detail that go missing with passive transformer output. People praise the smooth relaxed quality of naked traffos; IMO this suggests a loss of current drive.
The further improvement with dual mono B2 was surprising. More detail and separation and a tremendous payload of dynamic energy on transients and decay.
The further improvement with dual mono B2 was surprising. More detail and separation and a tremendous payload of dynamic energy on transients and decay.
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Thanks for the explanation.
For balanced mod, do you use 4 silver rocks? You said you directly compared buffered transformers to several approaches using I/V stages. Wondering what I/V stages you tried and how it compared to the silver rock + buffer. Based on what you wrote, I guess using B2 under voltage mod with buffered transformer is better than using say, simple resistor I/V followed by silver rocks, despite better dynamic range for the current mod?
The fact that you are noticing "surprising" improvement on dual mono is quite promissing. I have been communicating with Kyle at RAM, but the issue with silver rock for me is its cost, the performance of resulting DAC should be at least equal or better than that of high end DACs like EMM lab or DCS, which you are saying it is. I wonder whether you could describe the sound of your moded cd player more specifically with respect to some well known high end CDP or DAC, roughly how it is different and better, if at all possible? (I understand it can only be not so rigorous comparisons since you were listening to other players in audio fairs.) Thanks again!
John
In dual mono two transformers are sufficient. The DACs in each Sabre chip are summed by jumpering the left & right outputs—taking care that the jumpers are crossed over to obtain correct phase.
My initial experiment was a Sony SCD-1 DAC chip through silver traffos, tested both with and without the monolithic buffer. I tried this DAC both as a current and voltage source, with and without Sony’s op-amp based I/V stage in circuit. It sounded more natural as a voltage source, and more so with the buffer added on either side of the traffo. In the course of transplanting the transformer output stage to B2 I never tried a simple I/V resistor. Sometimes life is too short... I first tried B2 passively through traffo to XLR output. As with the Sony DAC, B2 with an unbuffered traffo had an appealing sweet & pretty sound, but was compromised by soft rounding at the frequency extremes, limited resolution, and somewhat wimpy dynamics. The addition of the buffer woke up B2 with more resolution, a sense of wide and neutral frequency balance, and taught natural timbres similar to DCS, EMM, Burmester, Playback Design, but with more authority, scale, tone, and organic flesh than those players. One thing I like about B2 is that this organic quality is not achieved with artificial “warmth”, i.e. blurring of LF detail or smeared midrange. There is a deep relaxing calm underneath articulated dynamic swings that turn on a dime. BTW it took many hours of break-in of Buffalo kit to reveal the finer points.
My initial experiment was a Sony SCD-1 DAC chip through silver traffos, tested both with and without the monolithic buffer. I tried this DAC both as a current and voltage source, with and without Sony’s op-amp based I/V stage in circuit. It sounded more natural as a voltage source, and more so with the buffer added on either side of the traffo. In the course of transplanting the transformer output stage to B2 I never tried a simple I/V resistor. Sometimes life is too short... I first tried B2 passively through traffo to XLR output. As with the Sony DAC, B2 with an unbuffered traffo had an appealing sweet & pretty sound, but was compromised by soft rounding at the frequency extremes, limited resolution, and somewhat wimpy dynamics. The addition of the buffer woke up B2 with more resolution, a sense of wide and neutral frequency balance, and taught natural timbres similar to DCS, EMM, Burmester, Playback Design, but with more authority, scale, tone, and organic flesh than those players. One thing I like about B2 is that this organic quality is not achieved with artificial “warmth”, i.e. blurring of LF detail or smeared midrange. There is a deep relaxing calm underneath articulated dynamic swings that turn on a dime. BTW it took many hours of break-in of Buffalo kit to reveal the finer points.
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As you mention, the caveat is that my comparisons are drawn from recent visits to audio fairs. Also, my experience with Buffalo is limited to RBCD-- which leans in Buffalo's favor, as so many exhibitors at the shows these days are demoing hi-res CPU files. I do have an excellent vinyl rig at home to use as a benchmark in judging CDP modifications. Recent Buffalo updates take RBCD much closer to LP quality than expected, and in certain respects I'm liking RBCD through Buffalo more than vinyl.
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Thanks for the most appropriate and eloquant description of the sound you achived. I like the fact that you are benchmarking a very good vinyl.
Do you mean when dual mono is used 2 silver rock are sufficient for balanced but for single buffalo you need 4 silver rock? Does silver rock have center tap in both primary and secondary? Also do you place buffer after B II and before the silver rock? Finally, with balanced set up, can one just use + and ground from silver for single ended use? This is not possible, as I understand, with Buffalo + TP iv stage, but I wonder whether it'd be O.K. with transformer output stage.
Thanks!
Two transformers, whether in stereo or dual mono. In dual mono the stereo outputs of each Buffalo pcb are paralleled-- both configurations look the same to the transformers except for the lower output impedance associated with dual mono. The Silver Rocks don't have a centertap. Connect the primaries to (+) and (-) at Buffalo output and float Buffalo ground. Connect the transformer secondaries to XLR pins 2 & 3; for SE output you ground the (-) phase. The buffers can be placed on either side of the transformer, but the number of buffers varies depending on their position and whether SE or balanced output is desired. I buffer the secondaries, with one buffer chip on each of four phases into two XLR outputs. For SE output just two buffers are needed, as anti-phase is tied to ground. Placing the four buffers on the transformer primaries makes for simpler wiring on the secondary side if you want the ability to switch between XLR and RCA outputs. In this case you would need to add a toggle switch between XLR pin 3 and RCA barrel.
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ESS9018 specially made IV transformer from Japan and Feastrex
New Japanese ESS9018 IV Transformers –a mini review
Executive summary: these new Japanese transformers are the best sounding IV transformers that the author have ever listened to, and compared to a highly modified Legato and a fully discrete all-FET IV converter, these transformers are sonically hard to beat.
I have tried both the amorphous core Lundahl LL1684 and Sowther 9545e audio transformers applied as IV converters, and although the sound has been good with the LL1684:s, and OK with the 9545e:s, they did not sound as good as the discrete IV converters I have. I actually gave up on transformers even though they had something special sonically. Instead I started to modify and upgrade my Legato, IVY, and fully discrete FET IV converters with new components, and the power supply super shunt regulators were modified as well.
I thought that I´d given up on transformers as the ultimate IV converter, when a few months back, Bunpei wrote to me about a new Japanese transformer distributed by Feastrex*, that was made especially for the ESS9018 DAC, and that this transformer used a special type of core material called FINEMET, which is a nano crystalline soft magnet material. I checked out the new material and got a few photos of the transformers, and two weeks later, I had a pair of unusually heavy transformers hooked up with solid core silver wire to my reference DAC, the Buffalo II with the three Tridents installed, playing music from the SDTrans384 memory card player I use daily.
Compared to having a dual mono, discrete IV converter with dual toroids for raw power supply, and dual super shunt regulators to feed the converters, hooking up a similar transformer setup, is unstressingly easy. For each channel, just connect two (GND is not needed) short wires from the Buffalo2´s output to the transformer, connect the three or two wires (balanced or unbalanced) from the transformer outputs to the line amplifier, and voila, you are done! Well, OK, you need to have a load resistor on the transformer outputs and maybe a small capacitor across the secondaries, too.
I used a 4,02k TX2352 bulk metal foil resistor connected directly at the transformer outputs as load resistor to get 2,0Vrms at 0dBFS into the Buffalo2. A 10nF RIFA PFE210 film and foil polystyrene capacitor was also soldered to the outputs, as I, on my oscilloscope, noted a ringing when only a resistive load was used. The cap removed the ringing, and also made the treble sound as it should. For the experimental person, lower resistance values and made of other resistor materials, and ditto for the capacitor could be fun try out. If a lower output voltage is wanted, just lower the resistor value. One could even use a volume control of top notch quality connected at the secondary windings to get the master volume control for one´s complete hifi system.
To make the comparisons between - first the Legato and the transformers - and secondly between the all-FET IV converter and the transformers, I used two identical Buffalo2 DAC:s that were both powered by identical Placid super shunt regulators. The two Buffalo2:s were via I2S connected to a single SDTrans384 memory card player. One of the Buffalo2’s was always connected to the transformers, whilst the other Buffalo2 was connected either to the Legato or to the all-FET IV converter.
After a week’s burn-in of the transformers using the repeat functionality of the SDTrans384, I started out to compare my Legato, with Duelund VSF 10 uF caps and only film and foil polystyrene caps for the other caps, against the transformers. These transformers, in general, sound more clean or pure, less foggy, and less fat. The bass is deep and more articulated from the transformers but the Legato has more fattiness and more weight. About like from a high Q loudspeaker. Women´s voices are clearer to hear with the transformers but maybe they lack a bit of “body” in the voices – or this is how it should sound like if the fog is removed.
The transformers have more accurate energy in the treble which might be disturbing listening to for ex “Love over gold” which, IMO, is having a too harsh treble. The Legato smoothes this over and makes the song almost enjoyable. I am very sensitive to bad sounding s- and tch-sounds from voices and these sounds are better reproduced with the transformers. Listening to snare drums or steel stringed acoustic guitars there is more snap and attack.
Exchanging the Legato for my reference, the all-FET IV converter, which also uses a TX2352 resistor in the most critical position, I immediately noticed that it has the same accurate energy in the treble, that the transformers have more articulation in the bass, and as earlier with the Legato, the transformers do not have the sound of a high Q loudspeaker. I am really like the bass reproduction of these transformers. It is deep and firm but not even a tad dominant over mid or treble.
Compared to the transformers, the treble from the all-FET converter sounds a bit cloudy. For ex. cymbals and tambourines sound more real with the transformers, with less hash and more details. Male voices have a tad less body from the transformers but this is more and more feeling as correct. The all-FET converter has a more forward reproduction with more authority and I get the feeling of a demo type reproduction.
What made me decide to use the Feastrex transformers as my reference IV converter, was that when I listened to a duet between a male and female singer. They sing at the same time, and both singers were positioned at the same spot in the 3D image. With the all-FET converter (and also the Legato) it was hard for me to hear every word that the woman sang, but with the transformers I could pick out every word. They are very detailed.
Seems like I will be enjoying transformers for a while J. As I like to experiment, I will be trying an Audiocap Teflon and tin foil capacitor, and also a Caddock Mk132 as load resistor.
At the type writer - Staccatiss
*Feastrex, a Japanese full range loudspeaker driver company, is distributing the ESS9018 transformers, but the design of the transformer is made by Mr. Yasuo Suzuki - a “typical” Japanese audiophile. Primary DC resistance is 14 Ohms, and secondary resistance is 16 Ohms, and the turn´s ratio is 1+1:1+1. The transformers can be had with black urushi coating that is supposed to dampen against microphony.
Information about FINEMET can be found here http://www.hitachi-metals.co.jp/prod/prod02/pdf/hl-fm9-e.pdf.
New Japanese ESS9018 IV Transformers –a mini review
Executive summary: these new Japanese transformers are the best sounding IV transformers that the author have ever listened to, and compared to a highly modified Legato and a fully discrete all-FET IV converter, these transformers are sonically hard to beat.
I have tried both the amorphous core Lundahl LL1684 and Sowther 9545e audio transformers applied as IV converters, and although the sound has been good with the LL1684:s, and OK with the 9545e:s, they did not sound as good as the discrete IV converters I have. I actually gave up on transformers even though they had something special sonically. Instead I started to modify and upgrade my Legato, IVY, and fully discrete FET IV converters with new components, and the power supply super shunt regulators were modified as well.
I thought that I´d given up on transformers as the ultimate IV converter, when a few months back, Bunpei wrote to me about a new Japanese transformer distributed by Feastrex*, that was made especially for the ESS9018 DAC, and that this transformer used a special type of core material called FINEMET, which is a nano crystalline soft magnet material. I checked out the new material and got a few photos of the transformers, and two weeks later, I had a pair of unusually heavy transformers hooked up with solid core silver wire to my reference DAC, the Buffalo II with the three Tridents installed, playing music from the SDTrans384 memory card player I use daily.
Compared to having a dual mono, discrete IV converter with dual toroids for raw power supply, and dual super shunt regulators to feed the converters, hooking up a similar transformer setup, is unstressingly easy. For each channel, just connect two (GND is not needed) short wires from the Buffalo2´s output to the transformer, connect the three or two wires (balanced or unbalanced) from the transformer outputs to the line amplifier, and voila, you are done! Well, OK, you need to have a load resistor on the transformer outputs and maybe a small capacitor across the secondaries, too.
I used a 4,02k TX2352 bulk metal foil resistor connected directly at the transformer outputs as load resistor to get 2,0Vrms at 0dBFS into the Buffalo2. A 10nF RIFA PFE210 film and foil polystyrene capacitor was also soldered to the outputs, as I, on my oscilloscope, noted a ringing when only a resistive load was used. The cap removed the ringing, and also made the treble sound as it should. For the experimental person, lower resistance values and made of other resistor materials, and ditto for the capacitor could be fun try out. If a lower output voltage is wanted, just lower the resistor value. One could even use a volume control of top notch quality connected at the secondary windings to get the master volume control for one´s complete hifi system.
To make the comparisons between - first the Legato and the transformers - and secondly between the all-FET IV converter and the transformers, I used two identical Buffalo2 DAC:s that were both powered by identical Placid super shunt regulators. The two Buffalo2:s were via I2S connected to a single SDTrans384 memory card player. One of the Buffalo2’s was always connected to the transformers, whilst the other Buffalo2 was connected either to the Legato or to the all-FET IV converter.
After a week’s burn-in of the transformers using the repeat functionality of the SDTrans384, I started out to compare my Legato, with Duelund VSF 10 uF caps and only film and foil polystyrene caps for the other caps, against the transformers. These transformers, in general, sound more clean or pure, less foggy, and less fat. The bass is deep and more articulated from the transformers but the Legato has more fattiness and more weight. About like from a high Q loudspeaker. Women´s voices are clearer to hear with the transformers but maybe they lack a bit of “body” in the voices – or this is how it should sound like if the fog is removed.
The transformers have more accurate energy in the treble which might be disturbing listening to for ex “Love over gold” which, IMO, is having a too harsh treble. The Legato smoothes this over and makes the song almost enjoyable. I am very sensitive to bad sounding s- and tch-sounds from voices and these sounds are better reproduced with the transformers. Listening to snare drums or steel stringed acoustic guitars there is more snap and attack.
Exchanging the Legato for my reference, the all-FET IV converter, which also uses a TX2352 resistor in the most critical position, I immediately noticed that it has the same accurate energy in the treble, that the transformers have more articulation in the bass, and as earlier with the Legato, the transformers do not have the sound of a high Q loudspeaker. I am really like the bass reproduction of these transformers. It is deep and firm but not even a tad dominant over mid or treble.
Compared to the transformers, the treble from the all-FET converter sounds a bit cloudy. For ex. cymbals and tambourines sound more real with the transformers, with less hash and more details. Male voices have a tad less body from the transformers but this is more and more feeling as correct. The all-FET converter has a more forward reproduction with more authority and I get the feeling of a demo type reproduction.
What made me decide to use the Feastrex transformers as my reference IV converter, was that when I listened to a duet between a male and female singer. They sing at the same time, and both singers were positioned at the same spot in the 3D image. With the all-FET converter (and also the Legato) it was hard for me to hear every word that the woman sang, but with the transformers I could pick out every word. They are very detailed.
Seems like I will be enjoying transformers for a while J. As I like to experiment, I will be trying an Audiocap Teflon and tin foil capacitor, and also a Caddock Mk132 as load resistor.
At the type writer - Staccatiss
*Feastrex, a Japanese full range loudspeaker driver company, is distributing the ESS9018 transformers, but the design of the transformer is made by Mr. Yasuo Suzuki - a “typical” Japanese audiophile. Primary DC resistance is 14 Ohms, and secondary resistance is 16 Ohms, and the turn´s ratio is 1+1:1+1. The transformers can be had with black urushi coating that is supposed to dampen against microphony.
Information about FINEMET can be found here http://www.hitachi-metals.co.jp/prod/prod02/pdf/hl-fm9-e.pdf.
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