Hi Ken
I feel honored by that, thanks. I don't like to sound like I have a big head, but I think a separate thread should be started by somebody, not just an Oppo topic, but can you imagine what it would look like if I started a thread on the "The 'Rasmussen Effect' on Delta-Sigma DACs" and it will always show me as the initiator of that thread? Don't mind the name, but I still need to be comfortable about it.
The good thing about the name Rasmussen, it is a very common name in Scandinavia, especially Denmark (in the top ten most common list) and Norway. So it will sound suitably 'generic' if the first name is not mentioned.
There is a 'Rasmussen Report' in the US, I believe they are a polling organisation.
Has anybody ever Googled their name? Let's be honest now. Well, have you any idea how many 'Joe Rasmussen's there are in the US alone? Lots.
So, if nobody objects, and if they feel it is deserved, then Rasmussen Effect, I can live with. Now just wonder what Pandora's Box has been opened?
Cheers, Joe
.
Trinity DAC
It would be very interesting because of the different approach in its DAC implementation.
And according to some (owners and reviewers) the best DAC ever to walk the surface of this planet.
Ok, I'll do that, even if I don't have any first hand personal listening experience with it. There is enough info here and there (with measurement graphs and links) to keep it interesting for many members here at diyAudio.
Thx for the suggestion.
* EDIT: Done! ...In the Digital Line Level section of the forums.
It would be very interesting because of the different approach in its DAC implementation.
And according to some (owners and reviewers) the best DAC ever to walk the surface of this planet.
Ok, I'll do that, even if I don't have any first hand personal listening experience with it. There is enough info here and there (with measurement graphs and links) to keep it interesting for many members here at diyAudio.
Thx for the suggestion.
* EDIT: Done! ...In the Digital Line Level section of the forums.
Last edited:
So far we have only really confirmed that the 'effect' works with delta-sigma DACs and that is a very obvious effect when heard.
But with NOS DACs, it may simply perceived as HF roll-off, if the cap value becomes too high and no sweet spot is heard before the roll-off becomes very obvious. No sweet spot, then nothing gained.
Cheers, Joe
And maybe we are closer to understanding why.
I have both types of DACs myself.
Cheers, Joe
As thought, as done it...
http://www.diyaudio.com/forums/digi...g-technique-rasmussen-effect.html#post3781505
Joe, you are invited to write first there more about, and then let`s see what happen...
I think it will be interesting...
http://www.diyaudio.com/forums/digi...g-technique-rasmussen-effect.html#post3781505
Joe, you are invited to write first there more about, and then let`s see what happen...
I think it will be interesting...
Last edited:
One word: Analog.
* A DAC like for example, the Burrr-Brown PCM-1704K (or PCM-63) sounds more 'analog' (smoother, more pleasant, less irritating, fuller, faithful, natural, ...) than another one from say Cirrus Logic (Crystal DAC - CSanything) or AKM DAC.
Yes, you can alter the sound of a delta-sigma DAC to make it more euphonic, from various implementations, and more similar to a turntable somehow; but a digital EQued turntable sound.
Just my own view anyway.
As thought, as done it...
http://www.diyaudio.com/forums/digi...g-technique-rasmussen-effect.html#post3781505
Joe, you are invited to write first there more about, and then let`s see what happen...
I think it will be interesting...
That's cool.
Just tuned into this discussion, and will need to read back further on what the posts brought up. A key point that triggered my attention is the bolded comment, a classic behaviour in digital sound tweaking - this is the sort of thing I've been 'battling' with for what feels like eons, though using other techniques.
Guys this thread was going along smoothly, but has suddenly started to derail. Please stop with the personal comments I will probably go back and cull a few posts. Edit: ok I've culled almost all of the recent posts. Please leave arguments in other threads where they are. That goes for both sides!
Last edited:
Hi Eric
Unfortunately I was correct.
But I have enough faith, but it will just take time - and just like I did the audio 'buffer' thing 12 years ago and now it's everywhere, they will forget me. Oh yes, that was me. lol
Off to bed.
Cheers, Joe
IV converter suggestions wanted
I've been working on AC powerline conditioning for both my amplifier and the OPPO. This helps a lot and I ended up buying a Furman elite-15 i, which I'm using together with some other filters for each component separately. This provides blacker blacks, and a more relaxed presentation, especially during the day. Then I discovered the Felix DIY common mode choke design for AC filters. Now I'm installing some of these, after the Furman, but before the amp and OPPO (to replace the other older filters). Actually, I think it would be very desirable to put a small Felix filter inside the OPPO, between the IEC receptacle and the analog transformer. This would separate the noise from the switching power supply from the analog section. I would also like to increase and replace some of the power supply filter capacitors and improve bypassing, but I haven't had time to look inside and get the measurements yet.
I've also been thinking about replacing the IV and output stages. I'm using both the balanced and unbalanced sections. The balanced goes directly to my amplifier, while the unbalanced is currently used for my subwoofer (although a buffered second balanced output would be better). My amplifier has a lot of gain, and so one volt AC would probably be more than enough output.
Ric has suggested using an OPA1632 op amp as a simple replacement. This is appealing, but I do worry a little about the single pole filtering arrangement. I would probably collect both pairs of IV differential outputs.
Currently, at night, my system sounds quite good, if a little on the resolving side, so I would benefit from more warmth and relaxation.
So I welcome suggestions for IV converter / output circuitry. I'm thinking that a discrete circuit could be superior. I'm willing to spend a little money for a developed circuit or a prebuilt board. Something like a legato or a Sen seem appealing. I'm looking for suggestions, reviews, or comments.
Thanks,
Eric
I've been working on AC powerline conditioning for both my amplifier and the OPPO. This helps a lot and I ended up buying a Furman elite-15 i, which I'm using together with some other filters for each component separately. This provides blacker blacks, and a more relaxed presentation, especially during the day. Then I discovered the Felix DIY common mode choke design for AC filters. Now I'm installing some of these, after the Furman, but before the amp and OPPO (to replace the other older filters). Actually, I think it would be very desirable to put a small Felix filter inside the OPPO, between the IEC receptacle and the analog transformer. This would separate the noise from the switching power supply from the analog section. I would also like to increase and replace some of the power supply filter capacitors and improve bypassing, but I haven't had time to look inside and get the measurements yet.
I've also been thinking about replacing the IV and output stages. I'm using both the balanced and unbalanced sections. The balanced goes directly to my amplifier, while the unbalanced is currently used for my subwoofer (although a buffered second balanced output would be better). My amplifier has a lot of gain, and so one volt AC would probably be more than enough output.
Ric has suggested using an OPA1632 op amp as a simple replacement. This is appealing, but I do worry a little about the single pole filtering arrangement. I would probably collect both pairs of IV differential outputs.
Currently, at night, my system sounds quite good, if a little on the resolving side, so I would benefit from more warmth and relaxation.
So I welcome suggestions for IV converter / output circuitry. I'm thinking that a discrete circuit could be superior. I'm willing to spend a little money for a developed circuit or a prebuilt board. Something like a legato or a Sen seem appealing. I'm looking for suggestions, reviews, or comments.
Thanks,
Eric
Won't suggest any mod's, but just comment on the "resolving side" aspect. Recorded music is complex, intense - if the system is working properly then an enormous amount will be resolved, automatically - because that's what's on the recording. If you want "warm and relaxing" then some form of filtering, "distortion" will be required, to modify what you hear. Which is fine, but just be aware that you're moving away from the recorded sound, rather than towards it ... just a thought I would keep in mind ...
Sorry, maybe that was poorly worded. The system is wonderful in many ways and is extremely resolving. After much work, female vocals are pure and very clear on modern high quality high-resolution recordings, and instruments are well-positioned and convincing in tone with lovely harmonics. Base is deep and taut.
Still, the system seems sometimes slightly unforgiving, or very slightly edgy especially during the day. Some of this may be my amplifier, which is certainly more responsible for the day night problem, and I also need more room treatment… So I'm working on all these things.
Still, the system seems sometimes slightly unforgiving, or very slightly edgy especially during the day. Some of this may be my amplifier, which is certainly more responsible for the day night problem, and I also need more room treatment… So I'm working on all these things.
Last edited:
For the price, and I know that Oppo has detractors, they have done a pretty good job. Oppo did not themselves design the three post-DAC circuits (XLR, RCA and Headphones) and used outsiders to do that.
I did somewhere earlier in this thread suggest an alternative circuit, based on the OPA-860.
Not sure of the post number... will look later for it, or you make try find it, I have an Oppo 105 here right now using it.
Cheers, Joe
PS: I found it, read from here onward: http://www.diyaudio.com/forums/digital-source/222596-oppo-s-bdp105-discussions-upgrading-mods-65.html#post3597677
.
Last edited:
Okay, slightly unforgiving, or edgy I 'get' - this is where things gets tricky, this is fine tuning of system aspects, where all sorts of factors which can be quite unexpected come into it.
Number one, I would forget the room treatment thing, that sort of "remedy" is band aid or crutch treatment, and will always never do everything properly. If it's a time of day thing then that sounds very much like it could be an interference artifact - something electrical switched on inside the house, the quality of the mains, where cell phones and suchlike are operating may be the cause.
If it were me, I would shut the house down totally, electrically, and see what that told me - or, fiddle with devices and techniques to improve the quality of the mains power that the components were seeing. Step at a time, try and change only one thing at a time, and narrow it down ...