rms
New Member
Posts: 4 
Audio Industry Affiliation: None
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Post by rms on Aug 24, 2019 14:42:36 GMT 10
First post at MAP  I was surprised to hear that using different power supplies affected the sound stage greatly. Since the sound stage was changing, fine details were lost as a consequence. In all likelihood, the cost of the power supply 12-15V dc would have to be very quiet to obtain a sound stage that is stable and has some depth to it, probably costing more than the itube2. I tried two SMPS units, the ifi iPower2 15VDC as it was supplied with the iTube2, and a bench power supply from Jaycar Cat # MP-3840. The post over at Head-fi details the connections and methods used in evaluating the ifi iTube 2 tube-valve buffer design and which supply did what. The conclusion is that the SMPS [15V - 150(300V)] internal to the itube2 would cause more problems that externally could not be solved. So for now, the iTube2 is back in the cupboard. So rule 1 of valves, don't use a small DC power supply to feed the whole device. Waiting for a Yaqin CD3 to arrive. |
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sandyk (RIP Alex, 1939 - 2021)
Global Moderator 
Posts: 226
About Me: Retired ex Principal Telecommunications Technical Officer with 43 years at Telstra (Australia)
I am also a Moderator in Hi Fi Critic Forum
Electronics hobbyist for >65 years with DIY projects including Loudspeakers, Stereo FM tuner, S/W Regen Receiver, Superhet AM ,
Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
Audio Industry Affiliation: NIL
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Post by sandyk (RIP Alex, 1939 - 2021) on Aug 24, 2019 15:10:34 GMT 10
First post at MAP I was surprised to hear that using different power supplies affected the sound stage greatly. Since the sound stage was changing, fine details were lost as a consequence. In all likelihood, the cost of the power supply 12-15V dc would have to be very quiet to obtain a sound stage that is stable and has some depth to it, probably costing more than the itube2. I tried two SMPS units, the ifi iPower2 15VDC as it was supplied with the iTube2, and a bench power supply from Jaycar Cat # MP-3840. The post over at Head-fi details the connections and methods used in evaluating the ifi iTube 2 tube-valve buffer design and which supply did what. The conclusion is that the SMPS [15V - 150(300V)] internal to the itube2 would cause more problems that externally could not be solved. So for now, the iTube2 is back in the cupboard. So rule 1 of valves, don't use a small DC power supply to feed the whole device. Waiting for a Yaqin CD3 to arrive. Hi Gary
You may also find diyah.boards.net/ of interest when it comes down to Vacuum Tube headphone amplifiers etc. They are designed by E.E. Frans de Gruitjer (Solderdude) who is a very experienced E.E. and even available in kit form IIRC.
Kind Regards Alex |
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rms
New Member
Posts: 4
Audio Industry Affiliation: None
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Post by rms on Aug 24, 2019 17:58:25 GMT 10
First post at MAP I was surprised to hear that using different power supplies affected the sound stage greatly. Since the sound stage was changing, fine details were lost as a consequence. In all likelihood, the cost of the power supply 12-15V dc would have to be very quiet to obtain a sound stage that is stable and has some depth to it, probably costing more than the itube2. I tried two SMPS units, the ifi iPower2 15VDC as it was supplied with the iTube2, and a bench power supply from Jaycar Cat # MP-3840. The post over at Head-fi details the connections and methods used in evaluating the ifi iTube 2 tube-valve buffer design and which supply did what. The conclusion is that the SMPS [15V - 150(300V)] internal to the itube2 would cause more problems that externally could not be solved. So for now, the iTube2 is back in the cupboard. So rule 1 of valves, don't use a small DC power supply to feed the whole device. Waiting for a Yaqin CD3 to arrive. Hi Gary
You may also find diyah.boards.net/ of interest when it comes down to Vacuum Tube headphone amplifiers etc. They are designed by E.E. Frans de Gruitjer (Solderdude) who is a very experienced E.E. and even available in kit form IIRC.
Kind Regards Alex Hi Alex, I will have a look at the site. The purpose of the valve buffer is to place it in the Tape Loop circuit with a gain of 1.0, so a quick AB can be made. The itube2, tonally wasn't bad, but with the sound stage akimbo, there was much distraction. The distortion is one aspect I worry about, however an article from VTL relates to an even order distortion relating to valve gear, so this may not be so bad. The buffer is inexpensive compared to a full blown pre-amp, and can be an adventure in ancient technology. As far as a power amplifier is concerned, a lot of tubes and the output transformers really complicate high power delivery, read also high current, so will stick with solid state for now. During research for valve pre-amps, the facilities most offer are very much on the lean side, for example tape monitor loops absent, line outs in XLR AND RCA. AR or VTL are about the only ones with multiple inputs, they aren't cheap either, so will try the buffer first, since I'm after the 'tone' of valves without the expense. |
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sandyk (RIP Alex, 1939 - 2021)
Global Moderator
Posts: 226
About Me: Retired ex Principal Telecommunications Technical Officer with 43 years at Telstra (Australia)
I am also a Moderator in Hi Fi Critic Forum
Electronics hobbyist for >65 years with DIY projects including Loudspeakers, Stereo FM tuner, S/W Regen Receiver, Superhet AM ,
Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
Audio Industry Affiliation: NIL
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Post by sandyk (RIP Alex, 1939 - 2021) on Aug 24, 2019 18:24:34 GMT 10
Hi Gary
You may also find diyah.boards.net/ of interest when it comes down to Vacuum Tube headphone amplifiers etc. They are designed by E.E. Frans de Gruitjer (Solderdude) who is a very experienced E.E. and even available in kit form IIRC.
Kind Regards Alex Hi Alex, I will have a look at the site. The purpose of the valve buffer is to place it in the Tape Loop circuit with a gain of 1.0, so a quick AB can be made. The itube2, tonally wasn't bad, but with the sound stage akimbo, there was much distraction. The distortion is one aspect I worry about, however an article from VTL relates to an even order distortion relating to valve gear, so this may not be so bad. The buffer is inexpensive compared to a full blown pre-amp, and can be an adventure in ancient technology. As far as a power amplifier is concerned, a lot of tubes and the output transformers really complicate high power delivery, read also high current, so will stick with solid state for now. During research for valve pre-amps, the facilities most offer are very much on the lean side, for example tape monitor loops absent, line outs in XLR AND RCA. AR or VTL are about the only ones with multiple inputs, they aren't cheap either, so will try the buffer first, since I'm after the 'tone' of valves without the expense. Hi Gary Years ago the MF Buffers were all the rage in Rock Grotto forum where I was assistant Admin. They still offer upgrade kits for the original too. This one is a clone.
Regards Alex www.aliexpress.com/item/1456387391.html
Alex
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Post by ROWUK on Aug 25, 2019 7:49:23 GMT 10
Of course the power supply is critical as all voltages (even the output) are supported there. There is not common agreement to how the PS should be built. Some favor low impedance, some high rejection others low capacity, others a high level of regulation.
I have always had the best results with power supplies with inductors. They seem to be less problematic with line noise or "other" mad electricity issues. I have not scientifically tested this, I just generally use inductors in power suppies - even for SS circuits.
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sandyk (RIP Alex, 1939 - 2021)
Global Moderator
Posts: 226
About Me: Retired ex Principal Telecommunications Technical Officer with 43 years at Telstra (Australia)
I am also a Moderator in Hi Fi Critic Forum
Electronics hobbyist for >65 years with DIY projects including Loudspeakers, Stereo FM tuner, S/W Regen Receiver, Superhet AM ,
Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
Audio Industry Affiliation: NIL
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Post by sandyk (RIP Alex, 1939 - 2021) on Aug 25, 2019 9:26:13 GMT 10
Of course the power supply is critical as all voltages (even the output) are supported there. There is not common agreement to how the PS should be built. Some favor low impedance, some high rejection others low capacity, others a high level of regulation. I have always had the best results with power supplies with inductors. They seem to be less problematic with line noise or "other" mad electricity issues. I have not scientifically tested this, I just generally use inductors in power suppies - even for SS circuits. Hi Robin There are advantages with the use of inductors in SS equipment too, but size, weight, and cost usually rules them out. E.E. John Swenson designed a nice +5V PSU for the Squeeze Box Touch that uses a choke, which was published in DIY Audio several years ago. You can also use a small value choke in power supplies for power amplifiers, as Silicon Chip magazine later did for their 20W Class A amplifier to reduce transformer buzz that some constructors reported. The main disadvantage though in a high current supply is that it may mean you need to use a higher voltage transformer to make up for the reduced output voltage. I can provide the explanation behind the reasons for the Silicon Chip change via email if anybody wishes to go further into this. Regards Alex Attachments:
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Post by ROWUK on Aug 25, 2019 20:20:03 GMT 10
As our sources of AC become less "analog" and more "on demand" (elimination of coal and atomic power generation), we will need to come up with power supplies to allow transparent reproduction. Many trustworthy ears complain about the quality and resort to UPS schemes like with Pure Power regenerators.
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sandyk (RIP Alex, 1939 - 2021)
Global Moderator
Posts: 226
About Me: Retired ex Principal Telecommunications Technical Officer with 43 years at Telstra (Australia)
I am also a Moderator in Hi Fi Critic Forum
Electronics hobbyist for >65 years with DIY projects including Loudspeakers, Stereo FM tuner, S/W Regen Receiver, Superhet AM ,
Synchrodyne PLL AM tuner (Phase Lock Loop),Stereo Tape Deck, Amplifiers including I.C. types, Class A, Class AB 100W/Ch. (ETI5000) 240W/Ch. Mosfet (AEM6000) ,several DACs , numerous PSUs including VERY low noise (<4uV) types etc.for myself and friends
Audio Industry Affiliation: NIL
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Post by sandyk (RIP Alex, 1939 - 2021) on Aug 25, 2019 21:20:48 GMT 10
As our sources of AC become less "analog" and more "on demand" (elimination of coal and atomic power generation), we will need to come up with power supplies to allow transparent reproduction. Many trustworthy ears complain about the quality and resort to UPS schemes like with Pure Power regenerators. The proliferation of Power derived from rooftop Solar Panels using an inverter ,going back into the network makes this aspect even more important as their frequency may not always be of a very high stability . |
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