jacco vermeulen said:
Say what, i visit your homepage 50 times a month for possible updates on the Yapidiyap without any difficulty and only count as 1 ?
What a subjective commercial attitude, it's an outrage !
Supposingly so, however if you are on DHCP the counter will (or should) increment each time your IP changes. Unless Internic came up with a different policy without letting me know (happened before).
Regarding the content, the HPS 2.0 and other home based chores kept me away from updating the site. Right now, I'm pondering between:
a) finishing YAP (case, etc...) as is.
b) HPS 3.0 with improved noise performance and a single case (rather than hosting the PSU in a separate case, defining an internal shield).
c) YAP OPS 2.2, which would implement a modified input stage, based on a nice idea suggested by Andy http://www.diyaudio.com/forums/showthread.php?postid=1681713#post1681713 I've already experimented this by adding to an existing board a small extensions and there isn't a huge improvement in AC (about 15% less THD), but every bit counts, isn't it?
d) Trying a new input stage for the YAP OPS. It's on the drawing board already.
Some input would be appreciated on what would be the best priority. Right now I'm tempted to go with b) My new SME Series IV tonearm is in the mail and I'm for the moment very excited about re-discovering the vinyl world.
P.S. Ok, I changed the counter to register all visits
syn08 said:
I'm so not sure it's a local ISP or DNS issue. Why? See: http://www.diyaudio.com/forums/showthread.php?postid=1704009#post1704009
atiq19 said:
The only missing YAP things are publishing the details (PCB layout, etc...) on my web site and finishing the construction (case, etc...). I haven't decided yet if I'll do another revision (with input buffers, following Andy's idea). There's only so much time available...
If you are looking for a starter project, I would though recommend starting with the VSOP amp. It's smaller, simpler and was experimentd with both MOSFET and bipolar output devices.
YAP Building
Ovidiu,
I thought YAP would have few refinements. Some of the comments made by ES (e.g. flying clamp in VAS, 2PC arrangement terminations, Servo without input cap etc) are worthwhile to look. Anyway, I am interested in YAP and wouldn't mind facing challenges while enjoying a complex DIY project .
Let me know anything I should know from design perspective before I start building it.
What would be the effect of C34 if I modify OPS so that none of the MOSFETS ever turns off (so called non-switching) in class-B?I wish to bias the output FETS to 210mA. What is the rule of thumb? I know about 100mA reported by Self for BJT class-B but don't think its equal for MOSFET and CFB amp.
Is dual layer PCB mandatory? I was going through TI hi-speed pcb design guidelines and found that not all hi-speed design lend itself to dual sided pcb ( issues related to ground plane, capacitance, loop gain response etc.).
-Atiq
Ovidiu,
I thought YAP would have few refinements. Some of the comments made by ES (e.g. flying clamp in VAS, 2PC arrangement terminations, Servo without input cap etc) are worthwhile to look. Anyway, I am interested in YAP and wouldn't mind facing challenges while enjoying a complex DIY project
.Let me know anything I should know from design perspective before I start building it.
What would be the effect of C34 if I modify OPS so that none of the MOSFETS ever turns off (so called non-switching) in class-B?I wish to bias the output FETS to 210mA. What is the rule of thumb? I know about 100mA reported by Self for BJT class-B but don't think its equal for MOSFET and CFB amp.
Is dual layer PCB mandatory? I was going through TI hi-speed pcb design guidelines and found that not all hi-speed design lend itself to dual sided pcb ( issues related to ground plane, capacitance, loop gain response etc.).
-Atiq
Re: YAP VS PGP
To me, they sound about the same. The only thing that is significanty different is the ability to drive 4ohm loads - YAP has all the muscle it needs. However, this has nothing to do with the amp topology (NDFL+EC vs. current feedback), but only with the power supply and the number and type of output devices. While the PGP power supply is on the weak side (2 x 300W toroids) and the number of lateral MOSFET devices (three per leg, six per channel, delivering max. 20 Amps) is low, YAP is fed by 2 x 500W toroids and has six vertical devices per channel, delivering about twice the PGP current (35 Amps).
My preference goes though for PGP into 8ohm loads and YAP for 4ohm loads. The VSOP amp will drive 2ohm loads (I already have two low noise 1KW toroids) and I'm really curious if this will make any difference.
atiq19 said:
To me, they sound about the same. The only thing that is significanty different is the ability to drive 4ohm loads - YAP has all the muscle it needs. However, this has nothing to do with the amp topology (NDFL+EC vs. current feedback), but only with the power supply and the number and type of output devices. While the PGP power supply is on the weak side (2 x 300W toroids) and the number of lateral MOSFET devices (three per leg, six per channel, delivering max. 20 Amps) is low, YAP is fed by 2 x 500W toroids and has six vertical devices per channel, delivering about twice the PGP current (35 Amps).
My preference goes though for PGP into 8ohm loads and YAP for 4ohm loads. The VSOP amp will drive 2ohm loads (I already have two low noise 1KW toroids) and I'm really curious if this will make any difference.
Re: YAP front end compensation
VSOP has the same performance target as YAP, while attempting to further simplify the topology. So far so good.
Not sure what you mean, and honestly I don't care much about what ES simulations are telling. The YAP front end has better performance than a vanilla Alexander front end, that's why I added the Hawksford cascode and modified the compensation. Rememeber, the whole YAP has a ULG of no less than 8MHz.
The YAP OPS needs a modified input stage and I'm still pondering if it's worth a revision or to go ahead with finishing the VSOP. Meantime, I diverted to build the HPS series of preamps, to little time, to many projects. It's just a matter of priorities.
EDIT: If you are interested in design philosophy, then you should contact ES directly. Unfortunately I don't have the time and the stomach to digest his late topologies. You should also consider building one of his designs, I'm sure this would make him very happy.
atiq19 said:
VSOP has the same performance target as YAP, while attempting to further simplify the topology. So far so good.
atiq19 said:
Not sure what you mean, and honestly I don't care much about what ES simulations are telling. The YAP front end has better performance than a vanilla Alexander front end, that's why I added the Hawksford cascode and modified the compensation. Rememeber, the whole YAP has a ULG of no less than 8MHz.
The YAP OPS needs a modified input stage and I'm still pondering if it's worth a revision or to go ahead with finishing the VSOP. Meantime, I diverted to build the HPS series of preamps, to little time, to many projects. It's just a matter of priorities.
EDIT: If you are interested in design philosophy, then you should contact ES directly. Unfortunately I don't have the time and the stomach to digest his late topologies. You should also consider building one of his designs, I'm sure this would make him very happy.
post 221
Hi Edmond,
From your previous post:
''What are C8,C13, R6 and R13 for? Looks like TMC, but it certainly doesn't improve THD. Without these components, I finally get 1.6ppm, almost the same value as Mr P. has measured.
This exercise leaves us with two questions:...''
Can you clarify your reasoning on YAP's front end compensation? When you said 'without this' did you mean no compensation at all for front end?
Cheers.
Atiq
Hi Edmond,
From your previous post:
''What are C8,C13, R6 and R13 for? Looks like TMC, but it certainly doesn't improve THD. Without these components, I finally get 1.6ppm, almost the same value as Mr P. has measured.
This exercise leaves us with two questions:...''
Can you clarify your reasoning on YAP's front end compensation? When you said 'without this' did you mean no compensation at all for front end?
Cheers.
Atiq
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