Hi Joshua_G
It's simply a current amplifier. I attach a link where it explains the Aikido pre-amplifier.
http://www.tubecad.com/Product_PDFs/9-Pin_Stereo_Rev_C.pdf
regards,
It's simply a current amplifier. I attach a link where it explains the Aikido pre-amplifier.
http://www.tubecad.com/Product_PDFs/9-Pin_Stereo_Rev_C.pdf
regards,
I see there 2 cascaded SRPP stages, neither current buffer nor current amplifier.
Hi,
The second stage is a cathode follower with active load. I guess with some imagination one could call it "current buffer", but the more traditional name is fine IMNSHO.
The active load could have been used to improve the overall performance of the follower (White Follower, Gomes Stage) but is wasted here instead on fixing a problem (powersupply noise) that should not exist in the first place in well designed equipment.
The comparison between the much older Gomes Design and the Aikido has been done quite a few times (it is quite easy to do) with the Gomes invariably taking first place...
But for that you need to build the circuits and listen to them, not just run sim's and pick the "winner"...
Ciao T
The second stage is a cathode follower with active load. I guess with some imagination one could call it "current buffer", but the more traditional name is fine IMNSHO.
The active load could have been used to improve the overall performance of the follower (White Follower, Gomes Stage) but is wasted here instead on fixing a problem (powersupply noise) that should not exist in the first place in well designed equipment.
The comparison between the much older Gomes Design and the Aikido has been done quite a few times (it is quite easy to do) with the Gomes invariably taking first place...
But for that you need to build the circuits and listen to them, not just run sim's and pick the "winner"...
Ciao T
Hi guys,
If the gurú says "build your own honeycomb resistors because they are better", then that's what I do.
https://picasaweb.google.com/lh/photo/-vULf_BUzel2XafYGCyvatMTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/pf08g41H6u3y3GctjpjTldMTjNZETYmyPJy0liipFm0?feat=directlink
Cheers,
M.
Hi,
I did.
Convert your Aikido into a Gomes and have a listen. JB covered the Gomes circuit extensively, concluding of course that Aikido was better because it has better power supply rejection (it seems he is incapable of considering anything else to be a relevant quality) in his simulation and leaving it at that.
Ciao T
I did.
Convert your Aikido into a Gomes and have a listen. JB covered the Gomes circuit extensively, concluding of course that Aikido was better because it has better power supply rejection (it seems he is incapable of considering anything else to be a relevant quality) in his simulation and leaving it at that.
Ciao T
I found this to be one of the worst sounding resistors I ever heard. Just totally sterile. But that is just my opinion. YMMV.
Hi,
There are other threads where you can find comments of mine on specifc solutions. This one here is John's gig (who incidentally does not care much for tubes, while I do).
Ciao T
There are other threads where you can find comments of mine on specifc solutions. This one here is John's gig (who incidentally does not care much for tubes, while I do).
Ciao T
I'm using a Mills MRA05 now and I think it sounds goo; not overly bright but and good in detail/resolving. Too bad the TX2575 is so pricey, it might be worth a try before discounting it.
I may also try a Riken or AMRG for grins....
I'm using a Mills MRA05 now and I think it sounds good; not overly bright but and good in detail/resolving. Too bad the TX2575 is so pricey, it might be worth a try before discounting it.
I may also try a Riken or AMRG for grins....
Silly spelling error in post, resubmitted. No such thing as "goo" sound, unless you are a new mother.
Hi ThorstenL,
I agree, circuits running on clean power supplies only have to cope with the passing signal and this is already difficult enough.
Fixing power supply noise with an Aikido driver stage works fine in theory, the problem is that it has to do this in practice as well. It is likely that low frequency noise is attenuated while higer frequency noise simply passes and inter-modulates with the signal being processed. This causes selective noise attenuation or coloring.
Also keep in mind that the circuit connected to the TDA1541A needs to offer inaudible noise levels, large bandwidth, fast settling time and very low linearity errors.
Amplifying low amplitude signals is likely to increase noise, limit bandwidth, increase settling time and increasing linearity errors.
That's why I no longer use this output stage concept.
I applied tubes in the octal D-I DAC and DI8M projects. Balanced passive I/V conversion, balanced input stage (twin triode) followed by a Broskie buffer. Spent a lot of time with tube rolling and testing effects of different coupling caps. I used tubes that were selected for lowest microphony / noise and closely matched triode characteristics.
Later I experimented with Aikido amplifiers and DC-coupled tube amplifiers with OTL output.
Few days ago I even experimented with a balanced crystal oscillator based on a twin triode.
If tubes offer advantages over semiconductors in a specific application I wouldn't hesitate to use them.
I agree, circuits running on clean power supplies only have to cope with the passing signal and this is already difficult enough.
Fixing power supply noise with an Aikido driver stage works fine in theory, the problem is that it has to do this in practice as well. It is likely that low frequency noise is attenuated while higer frequency noise simply passes and inter-modulates with the signal being processed. This causes selective noise attenuation or coloring.
Also keep in mind that the circuit connected to the TDA1541A needs to offer inaudible noise levels, large bandwidth, fast settling time and very low linearity errors.
Amplifying low amplitude signals is likely to increase noise, limit bandwidth, increase settling time and increasing linearity errors.
That's why I no longer use this output stage concept.
I applied tubes in the octal D-I DAC and DI8M projects. Balanced passive I/V conversion, balanced input stage (twin triode) followed by a Broskie buffer. Spent a lot of time with tube rolling and testing effects of different coupling caps. I used tubes that were selected for lowest microphony / noise and closely matched triode characteristics.
Later I experimented with Aikido amplifiers and DC-coupled tube amplifiers with OTL output.
Few days ago I even experimented with a balanced crystal oscillator based on a twin triode.
If tubes offer advantages over semiconductors in a specific application I wouldn't hesitate to use them.
Hi roger57,
I agree with erin, bulk metal foil resistors for passive I/V conversion sound detailed, yet sterile and "thin". This is a bit surprising as these resistors offer very low noise levels, low inductance and low stray capacitance. So other factors like resistor geometry may be causing this.
Carbon resistors are noisy, Riken or AMRG resistors with cool gold plated wires are no exception. When used as passive I/V resistor, its noise spectrum will emphasize specific frequencies. This leads to sound coloration and masking of details.
I suggest to use home made non-inductive wire wound resistors with low stray capacitance like maxlorenz did.
If you want to use off-the-shelf non-inductive wire wound resistors you could try Rhopoint or Neohm.
I agree with erin, bulk metal foil resistors for passive I/V conversion sound detailed, yet sterile and "thin". This is a bit surprising as these resistors offer very low noise levels, low inductance and low stray capacitance. So other factors like resistor geometry may be causing this.
Carbon resistors are noisy, Riken or AMRG resistors with cool gold plated wires are no exception. When used as passive I/V resistor, its noise spectrum will emphasize specific frequencies. This leads to sound coloration and masking of details.
I suggest to use home made non-inductive wire wound resistors with low stray capacitance like maxlorenz did.
If you want to use off-the-shelf non-inductive wire wound resistors you could try Rhopoint or Neohm.
Hi,
I would second Rohpoint, Neohm less. Rohpoint are truely excellent. For my first TDA1541 Non-OS DAC (in 98) I handmade bifilar wound Non-inductive 25 Ohm resistors. In susequent builds I compared to Rohpoint (which I have used extensively and found no reason to handwind resistors.
In my commercial designs we use a specfic type of SMD resistors after auditioning tons. Some SMD resistors are really bad, some are so-so and some are most excellent, though no patch for a Rohpoint Squaristor GR102.
Ciao T
I would second Rohpoint, Neohm less. Rohpoint are truely excellent. For my first TDA1541 Non-OS DAC (in 98) I handmade bifilar wound Non-inductive 25 Ohm resistors. In susequent builds I compared to Rohpoint (which I have used extensively and found no reason to handwind resistors.
In my commercial designs we use a specfic type of SMD resistors after auditioning tons. Some SMD resistors are really bad, some are so-so and some are most excellent, though no patch for a Rohpoint Squaristor GR102.
Ciao T
Where can i get the wire for build the honeycomb resistor?
Hi guys,
If the gurú says "build your own honeycomb resistors because they are better", then that's what I do.
https://picasaweb.google.com/lh/photo/-vULf_BUzel2XafYGCyvatMTjNZETYmyPJy0liipFm0?feat=directlink
https://picasaweb.google.com/lh/photo/pf08g41H6u3y3GctjpjTldMTjNZETYmyPJy0liipFm0?feat=directlink
Cheers,
M.
Dady,
Ive got heaps of wire, have a read here: http://www.diyaudio.com/forums/swap...ameter-constantan-isotan-resistance-wire.html
Ryan
Ive got heaps of wire, have a read here: http://www.diyaudio.com/forums/swap...ameter-constantan-isotan-resistance-wire.html
Ryan