AK4393 with 6N6P
Hi All, I have a squeezebox which on its own has a wonderful sound, very open and pure. I wanted to experiment with some tube output stages on this following on from a very successful mod of my TDA1541 Marantz CD30 player.
I've lifted both the + side outputs from the AK4393, feeding them onto the grids of two 6n6p in SRPP mode with separate B+ supplies. Initially i tried using both diff outputs from the chip with the (-) output onto the cathode of the lower triode for a poor man's unbalancer. I didn't like this at all. The sound was very strained and this config offers far too much gain. Unlistenable in my opinion. Reverting to just a single (+) output to each grid, leaving the (-) output loaded on the unused op-amp IC, the sound is amazing. I always know when something is 'right' because i feel the need to listen to all of my fav albums in one sitting
A/B comparisons between the standard squeezebox output and the ak4393/6n6p stage prove that the sound is way more open and detailed from the ak4393/6n6p combination. Its easy to hear each instrument/voice in the music. I'm really quite astounded by this bit of kit.
see the link below for pic of my proto.. The big caps are AeroVox on the B+ to each tube.. Overkill but a solid HT.
http://3.bp.blogspot.com/-LZJ-dwxDdV8/UPML7TzgcNI/AAAAAAAAAwk/sphTpOwFKy4/s1600/photo-780684.JPG
Hi All, I have a squeezebox which on its own has a wonderful sound, very open and pure. I wanted to experiment with some tube output stages on this following on from a very successful mod of my TDA1541 Marantz CD30 player.
I've lifted both the + side outputs from the AK4393, feeding them onto the grids of two 6n6p in SRPP mode with separate B+ supplies. Initially i tried using both diff outputs from the chip with the (-) output onto the cathode of the lower triode for a poor man's unbalancer. I didn't like this at all. The sound was very strained and this config offers far too much gain. Unlistenable in my opinion. Reverting to just a single (+) output to each grid, leaving the (-) output loaded on the unused op-amp IC, the sound is amazing. I always know when something is 'right' because i feel the need to listen to all of my fav albums in one sitting
A/B comparisons between the standard squeezebox output and the ak4393/6n6p stage prove that the sound is way more open and detailed from the ak4393/6n6p combination. Its easy to hear each instrument/voice in the music. I'm really quite astounded by this bit of kit.see the link below for pic of my proto.. The big caps are AeroVox on the B+ to each tube.. Overkill but a solid HT.
http://3.bp.blogspot.com/-LZJ-dwxDdV8/UPML7TzgcNI/AAAAAAAAAwk/sphTpOwFKy4/s1600/photo-780684.JPG
I have a 15-0-15 3A transformer. It says in the ebay ad that you can jumper the 9V supply off one side of the 30V CT transformer thereby eliminating a 2nd transformer. Wouldn't this cause the transformer to become "unbalanced"? (By about 26mA. by the looks of it.)
Thank you for all the help Dario
The 150Ohm PRP's are in the DAC and I am just shocked over the quality of the sound (My Denon DCD-S10 and Denon DVD-3910 internal DAC's have no where near this sound quality)
The 150Ohm PRP's are standing in the "Socket,IC,SIP,2.54mm,Sn/Au" that you mentioned in earlyer post.
I am would like to test out some Carbon Film resistors that you mention, are the Takman REX a good choice here and are there maybe other types worth testing out? I see in the BOM that The Takman REY metal film are mentioned?
PS! I just ordered some 10nF Philips Polystyrene for testing.
@ Erin & Dario,
Thank you for your patience I have just finished reading the entire thread -wow this is long- and both of you have answered repetitive questions, not reacted to criticism, and exceeded in helping the noobs (of which I am one).
I am preparing to coagulate four of these DAC's into a 4-way active speaker project I am working on.
The components I have ordered thus far are:
4 x 2496 DAC kits (un-assembled, but with all the components and SMD mounted)
4 x Dario's complete BOM parts
4 x Dario's simplified shunt regulator parts
1 x Custom toroidal transformer 110v primary 15v-0-15v(30w), 15v-0-15v(30w), 15v-0-15v(30w), 15v-0-15v(30w) $65 shipped
1 x nanoDIGI 2x8K | miniDSP for stereo 4 way crossover
I will be using this setup to feed line level signal to a pair of Parasound HCA-2205 amps I already have (5x220watts) into 4 x IB318 subs, 2 x Dynaudio 12's, 2 x Dynaudio 3" dome mids, and 2 x 1" Dynaudio soft dome tweets. All calibrated via REW using a Tascam US-144MKii and a EMM-6 calibrated mic. Eventually I'll upgrade the Dynaudio drivers to JBL Selenium pro audio drivers, but that's about $1100 down the road, the Dynaudio's I have now...
I'll post up more as stuff arrives and the build begins. I do have a few questions though.
Is there anything to be done so far as tuning the individual DAC's specifically to the crossover sections they will reproduce? I.e. <50hz, 50-150hz, 150-3khz, >3khz (rough numbers for example only)
Would I be better off pulling the +5v and +3.3v sections (digital and analog separately) off the 15v-0-15v lines as per Dario's shunt diagram in google doc's for each DAC individually (with the addition of a second +5v leg on the opposing 15v output) -OR- a dedicated 12vdc (8 amp) power supply that would group all the <5v shunt supplies from a single preconditioned DC source?
Last for now, factual info only, would a vacuum tube "unbalancer" output stage be a more ACCURATE amplifiaction of the 4396's analog outputs vs. the dual OPA827 opamp -without- concern for the frequency response correction the LPF the opamp's perform, as I can compensate for this in the active crossover prior to the DAC's?
^^^ this question is really directed at Erin and Dario as I can see they read data sheets and I'm down with that, but if you can give technically accurate information and not speculation, I'd like your wisdom too
First post is always long LoL Sorry
Thank you for your patience
I have just finished reading the entire thread -wow this is long- and both of you have answered repetitive questions, not reacted to criticism, and exceeded in helping the noobs (of which I am one). I am preparing to coagulate four of these DAC's into a 4-way active speaker project I am working on.
The components I have ordered thus far are:
4 x 2496 DAC kits (un-assembled, but with all the components and SMD mounted)
4 x Dario's complete BOM parts
4 x Dario's simplified shunt regulator parts
1 x Custom toroidal transformer 110v primary 15v-0-15v(30w), 15v-0-15v(30w), 15v-0-15v(30w), 15v-0-15v(30w) $65 shipped
1 x nanoDIGI 2x8K | miniDSP for stereo 4 way crossover
I will be using this setup to feed line level signal to a pair of Parasound HCA-2205 amps I already have (5x220watts) into 4 x IB318 subs, 2 x Dynaudio 12's, 2 x Dynaudio 3" dome mids, and 2 x 1" Dynaudio soft dome tweets. All calibrated via REW using a Tascam US-144MKii and a EMM-6 calibrated mic. Eventually I'll upgrade the Dynaudio drivers to JBL Selenium pro audio drivers, but that's about $1100 down the road, the Dynaudio's I have now...
I'll post up more as stuff arrives and the build begins. I do have a few questions though.
Is there anything to be done so far as tuning the individual DAC's specifically to the crossover sections they will reproduce? I.e. <50hz, 50-150hz, 150-3khz, >3khz (rough numbers for example only)
Would I be better off pulling the +5v and +3.3v sections (digital and analog separately) off the 15v-0-15v lines as per Dario's shunt diagram in google doc's for each DAC individually (with the addition of a second +5v leg on the opposing 15v output) -OR- a dedicated 12vdc (8 amp) power supply that would group all the <5v shunt supplies from a single preconditioned DC source?
Last for now, factual info only, would a vacuum tube "unbalancer" output stage be a more ACCURATE amplifiaction of the 4396's analog outputs vs. the dual OPA827 opamp -without- concern for the frequency response correction the LPF the opamp's perform, as I can compensate for this in the active crossover prior to the DAC's?
^^^ this question is really directed at Erin and Dario as I can see they read data sheets and I'm down with that, but if you can give technically accurate information and not speculation, I'd like your wisdom too
First post is always long LoL
Sorry
I presume you are talking about this unbalancer
In which case, since I cant find any THD + noise specifications for this circuit, it will be hard to answer in the manner which you request. Perhaps writing to tube CAD website, might provide you with these figures. Though on that page was written "The distortion is still amazingly low and the PSRR is still exceptionally fine"
"Accurate" is an interesting term. Any DAC chip designed according to the manufactures datasheet will have low distortion and flat frequency response. But.. somehow they all manage to sound a bit different.
So I think it all comes down to tuning or refining, or matching components in your system, to get the sound you like.
I have owned numerous DACs. And heard even more than I have owned.
My favourite sounding ones have tube output stages.
The parts listed on the Dario's BOM, and my alternate suggestions, are "tuned" with full frequency audio in mind. From personal experience, it is possible to install different values or brands of components that will emphisise certain frequencies, and make some frequencies sound really good, but to the detriment of a well balanced sound.
Since you intend to use multiple boards in a active crossover, I think you will be able to tune them according to the frequnecies they will reproduce, but I have no specific recommendations other than to suggest experimenting for youself. good luck.
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If anyone in Europe/Scandinavia is interested I'm buying some polystyrene caps for this DAC and a phono stage from the cheapest source I know - JAB Electronic Components for Radio Hams & Hobbyists in the UK. Not only is this the cheapest polys I can find eg. 680pF/630V @ £0.50 or 10 x @ £4/ 3300pF/160V @ £0.50 or 10 x @ £4. and the postage is the cheapest as well.
I say the cheapest but they are still making a very good profit on the postage @ £3.75 for the UK & mainland Europe - I weighed 4 poly caps = 2g, so the 10 caps I want would be 5g + an envelope and a bit of bubble wrap = £0.87p. Others quoted £4.50 - £7.50 and that was for (1) cap - simply outrageous - do these companies declare the big profits they make on postage - do they hell.
So, take a look at the site and let me know by PM if interested in the next 24 hours - postage costs will be shared pro rata and I have plenty of envelopes and bubblewrap to post the caps on, so will only charge what it costs me via La Poste.
If the total order is £30 or over, the postage is free from the UK to me here in France.
I say the cheapest but they are still making a very good profit on the postage @ £3.75 for the UK & mainland Europe - I weighed 4 poly caps = 2g, so the 10 caps I want would be 5g + an envelope and a bit of bubble wrap = £0.87p. Others quoted £4.50 - £7.50 and that was for (1) cap - simply outrageous - do these companies declare the big profits they make on postage - do they hell.
So, take a look at the site and let me know by PM if interested in the next 24 hours - postage costs will be shared pro rata and I have plenty of envelopes and bubblewrap to post the caps on, so will only charge what it costs me via La Poste.
If the total order is £30 or over, the postage is free from the UK to me here in France.
My DAC is singing
Succesfull from the first start, my DAC is singing and it sounds really good.
Apart few caps i've ordered from Distrelec the recommended parts by Dario,
I'm sad because i've tried to connect an optical received as my transport is having only optical output with no success.
Maybe my optical receiver is defective, who knows.
I'm using a single 2x15v transformer. Makes sense to look for a transformer with a separated 9v winding ?
I have a small concern regarding the group of 3k resisor and the two 10nf 22nf caps wich forms the PLL for CS8416. In datasheet it is strongly recommended to use ceramic caps with very short traces. This 3 parts are very important in jitter level.
I want to thank to Dario and the others for a well documented BOM and mods.
Succesfull from the first start, my DAC is singing and it sounds really good.
Apart few caps i've ordered from Distrelec the recommended parts by Dario,
I'm sad because i've tried to connect an optical received as my transport is having only optical output with no success.
Maybe my optical receiver is defective, who knows.
I'm using a single 2x15v transformer. Makes sense to look for a transformer with a separated 9v winding ?
I have a small concern regarding the group of 3k resisor and the two 10nf 22nf caps wich forms the PLL for CS8416. In datasheet it is strongly recommended to use ceramic caps with very short traces. This 3 parts are very important in jitter level.
I want to thank to Dario and the others for a well documented BOM and mods.
An externally hosted image should be here but it was not working when we last tested it.
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