Hi Hugh,
You design seem interesting for a newbie like me. I will go for 2 board + 2P from the second GB unless you have sapre one available. I will start in either the FetziLLA or the Gainclone since both use the saem transformer (300VA 25VAC x 2).
The power supply schematic has Dr1, Dr3 in separate box but the Dr2 and Dr4 are in the same box, they are all BYQ28E, what is the meaning of that? ARe Dr1,DR3 are singleton and Dr3/Dr4 are dual diode? Why the D1A require heat sink?
The BOM shown D1A/B/C 625-BYQ28E-200-E3 quanty is 2,
Same thing for D1A/B/C which is different form the schematic provided. Got confuse.
Will you be able to provide the L1 as part of the kit?
Thanks
You design seem interesting for a newbie like me. I will go for 2 board + 2P from the second GB unless you have sapre one available. I will start in either the FetziLLA or the Gainclone since both use the saem transformer (300VA 25VAC x 2).
The power supply schematic has Dr1, Dr3 in separate box but the Dr2 and Dr4 are in the same box, they are all BYQ28E, what is the meaning of that? ARe Dr1,DR3 are singleton and Dr3/Dr4 are dual diode? Why the D1A require heat sink?
The BOM shown D1A/B/C 625-BYQ28E-200-E3 quanty is 2,
Same thing for D1A/B/C which is different form the schematic provided. Got confuse.
Will you be able to provide the L1 as part of the kit?
Thanks
Assessing the potential hum problems is not easy because of so many factors involved. It can not be done by testing the amp on the table, it has to be fully assembled to do it right. My amp is very quiet fully assembled, but I have used much different design for PSU. If anybody is interested in my filtering scheme I can pot it here.
George
George
I just got my Fetzilla playing music this morning. Need more time before posting any real impressions.
However, I have NO hum issues and I did the standard stock build. I do have some turn on thump though.
However, I have NO hum issues and I did the standard stock build. I do have some turn on thump though.
Mike,
Here it is. The filter you see before transformer is standard EMI filter inside power connector. This is floated ground design and there is only one connection to the chassis trough R11 for safety reason. I also made modification to the ground distribution on Fetzilla PCB to remove high current path from the ground traces. I run two AWG16 (1.3mm) bare wires in parallel beginning at C16-C14-C12-speaker cold spade-C11-C13-C18. Please note that input's GND pin is not connected to this wire. In addition to that all my input and output connectors are insulates from chassis. All series resistors on the rails are wire-wound type (you need as much inductance here as you can get). If you add the wires (about 8" AWG12) between PSU and Fetzilla PCB you will get triple PI filter on each rail. Measured ripple at the end of filter is 101mVAC at full 50W output load. Hope this helps.
George
Here it is. The filter you see before transformer is standard EMI filter inside power connector. This is floated ground design and there is only one connection to the chassis trough R11 for safety reason. I also made modification to the ground distribution on Fetzilla PCB to remove high current path from the ground traces. I run two AWG16 (1.3mm) bare wires in parallel beginning at C16-C14-C12-speaker cold spade-C11-C13-C18. Please note that input's GND pin is not connected to this wire. In addition to that all my input and output connectors are insulates from chassis. All series resistors on the rails are wire-wound type (you need as much inductance here as you can get). If you add the wires (about 8" AWG12) between PSU and Fetzilla PCB you will get triple PI filter on each rail. Measured ripple at the end of filter is 101mVAC at full 50W output load. Hope this helps.
George
George,
Very nice design, thorough, lots of capacitance, intercap resistors, bleeders, snubbers, WOW!! Should be very, very quiet.....
Syklab, do a datasheet search on BYQ28E-150. All will be revealed..... thank you for the correction on the BYQ order numbers on the BOM. I will amend it.
Here's the link to #2 FetZilla Group Buy, thanks also to Steve: http://www.diyaudio.com/forums/aksa/198170-group-buy-2-fetzilla.html
Cheers,
Hugh
Very nice design, thorough, lots of capacitance, intercap resistors, bleeders, snubbers, WOW!! Should be very, very quiet.....
Syklab, do a datasheet search on BYQ28E-150. All will be revealed..... thank you for the correction on the BYQ order numbers on the BOM. I will amend it.
Here's the link to #2 FetZilla Group Buy, thanks also to Steve: http://www.diyaudio.com/forums/aksa/198170-group-buy-2-fetzilla.html
Cheers,
Hugh
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Hugh
How about exploring a 100 watt Fetzilla design in the future ?
Regards & looking forward to being the first in Africa with this amp !
Jozua
How about exploring a 100 watt Fetzilla design in the future ?
Regards & looking forward to being the first in Africa with this amp !
Jozua
Jozua,
I will examine it. But I would go for a quasi, which in my experience are sonically better than fully complementary designs.
I look forward to your package arriving in Cape Town.... won't be long now, and hoping you can use an iron as your arm picks up!
Cheers,
Hugh
I will examine it. But I would go for a quasi, which in my experience are sonically better than fully complementary designs.
I look forward to your package arriving in Cape Town.... won't be long now, and hoping you can use an iron as your arm picks up!
Cheers,
Hugh
Hugh
I would love to hear a more powerful version of this design driving bigger speakers and coping with more demanding loads.
Regards
Jozua
I would love to hear a more powerful version of this design driving bigger speakers and coping with more demanding loads.
Regards
Jozua
Hugh
Package received !
Damm those output devices are small and fragile looking !!
Thx !!
Jozua
Package received !
Damm those output devices are small and fragile looking !!
Thx !!
Jozua
Well, this thread has been quiet for awhile now. I have now had a couple weeks of living with my FetZilla and can offer a short opinion on it.
At initiation two weeks ago my opinion pretty much mirrored Woody's initial impressions. There was no "Wow" factor whatsoever. There was just music. But I never really found it to be "like a single malt Scotch whiskey". In comparison to my Aspen Lifeforce, the fetZ seemed a little less. And it did have less, in the way of gain, several decibels less. Once I adjusted for this, the fetZ came up quite a bit in performance. I only had 3-4 hours of burn in testing before connecting everything so I thought I needed to give it more time before writing anything else.
It has plenty of time on it now. I now find the fetZ to be a splendid performing amplifier. It has pretty good bass, which it seemed to initially lack a little in comparison to the LF, and has excellent definition and tonality everywhere. I find it a step up from the LF. I have heard the new Naksa series of Hugh's amp. The fetZ is not a Naksa wannabee, though it does share some characteristics with it.
One area where I do find the fetZ to really shine is in sound width. This amp gives a really big sound. Much of my listening is to romantic era symphonies and concertos. These sound really big and large in the room now, moreso than with the LF amp. This is a real plus for me.
This FetZilla project is a great way to get into really good sound for not much investment, though it does require a fair bit of hands on knowledge beyond just soldering some components onto a pcb.
Here are some particulars on what I did and used:
Parts were procured from Newark, Digi-key, and Mouser. Newark has a good deal on 160VA/24V transformers from Triad.
Heatsinks were from Heatsink USA. I had to buy a tapping set to make the mounting holes for the board. I had not done this before, and this takes a bit of patience and care.
Case is an aluminum 12x12x4 from Par-Metal. Everything fits inside, though tightly, but I meant to get a 16x12x4 case, and I think this would work a little better.
Oh, and lastly, the heatsinks get quite warm, warmer than I expected. I presume this is normal. My other Aspen amps have all had rather cool heatsinks, so I was initially surprised by the heat. But all seems okay.
At initiation two weeks ago my opinion pretty much mirrored Woody's initial impressions. There was no "Wow" factor whatsoever. There was just music. But I never really found it to be "like a single malt Scotch whiskey". In comparison to my Aspen Lifeforce, the fetZ seemed a little less. And it did have less, in the way of gain, several decibels less. Once I adjusted for this, the fetZ came up quite a bit in performance. I only had 3-4 hours of burn in testing before connecting everything so I thought I needed to give it more time before writing anything else.
It has plenty of time on it now. I now find the fetZ to be a splendid performing amplifier. It has pretty good bass, which it seemed to initially lack a little in comparison to the LF, and has excellent definition and tonality everywhere. I find it a step up from the LF. I have heard the new Naksa series of Hugh's amp. The fetZ is not a Naksa wannabee, though it does share some characteristics with it.
One area where I do find the fetZ to really shine is in sound width. This amp gives a really big sound. Much of my listening is to romantic era symphonies and concertos. These sound really big and large in the room now, moreso than with the LF amp. This is a real plus for me.
This FetZilla project is a great way to get into really good sound for not much investment, though it does require a fair bit of hands on knowledge beyond just soldering some components onto a pcb.
Here are some particulars on what I did and used:
Parts were procured from Newark, Digi-key, and Mouser. Newark has a good deal on 160VA/24V transformers from Triad.
Heatsinks were from Heatsink USA. I had to buy a tapping set to make the mounting holes for the board. I had not done this before, and this takes a bit of patience and care.
Case is an aluminum 12x12x4 from Par-Metal. Everything fits inside, though tightly, but I meant to get a 16x12x4 case, and I think this would work a little better.
Oh, and lastly, the heatsinks get quite warm, warmer than I expected. I presume this is normal. My other Aspen amps have all had rather cool heatsinks, so I was initially surprised by the heat. But all seems okay.
During this development of this design over on the other thread I noticed that PSRR was not that great and proposed filters in both rails consisting of 20R + 470uF between the o/p & vas/ip stages.
I think this has now been modified a bit to better suit Hugh's version here but the principal I believe remains the same.
So I thought I should report that I just added 22,000uF across the 470uF and noticed good improvements in the bass, midrange and general effortlessness & fluidity of the sound.
It may be 22,000uF is over the top and as you have different value resistors in the different rails there might be a different optimal solution but I would recommend you check this out.
cheers
mike
I think this has now been modified a bit to better suit Hugh's version here but the principal I believe remains the same.
So I thought I should report that I just added 22,000uF across the 470uF and noticed good improvements in the bass, midrange and general effortlessness & fluidity of the sound.
It may be 22,000uF is over the top and as you have different value resistors in the different rails there might be a different optimal solution but I would recommend you check this out.
cheers
mike
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Mike,
I've found that PSRR with amps is much vaunted but less significant than you would expect. There are inevitable distortions in ALL amps, but rather than seeking to reduce them to vanishingly low levels I have found that it's best to manipulate the various artefacts and 'work' with them. I have even found with single ended input and voltage amp circuits that too much decoupling can actually degrade the music presentation; so I conclude that there are other factors operating here, and I would assume it is phase. If the VAS and the output device are operating from the same rail then there will be serious interaction, BUT, that interaction will be in phase at the VAS emitter/source. Viewed on the collector/drain side, the phase is reversed, and this can work for you. Use a large cap and resistor/diode to decouple the VAS emitter/source from the output device and you subtly change the phase each see; this then affects the scalar amplitude of the artefacts as they present to the gates of the output stage.
As in all things audio, you do what you think is best, but there are a thousand ways to kill a cat and while it may be tempting to say one is better than another, such is the diversity of human psychoacoustic preferences that it's probably more appropriate to simply say that it's different......
Thanks for your great input and obvious excellence with this amp, much appreciated.
Cheers,
Hugh
I've found that PSRR with amps is much vaunted but less significant than you would expect. There are inevitable distortions in ALL amps, but rather than seeking to reduce them to vanishingly low levels I have found that it's best to manipulate the various artefacts and 'work' with them. I have even found with single ended input and voltage amp circuits that too much decoupling can actually degrade the music presentation; so I conclude that there are other factors operating here, and I would assume it is phase. If the VAS and the output device are operating from the same rail then there will be serious interaction, BUT, that interaction will be in phase at the VAS emitter/source. Viewed on the collector/drain side, the phase is reversed, and this can work for you. Use a large cap and resistor/diode to decouple the VAS emitter/source from the output device and you subtly change the phase each see; this then affects the scalar amplitude of the artefacts as they present to the gates of the output stage.
As in all things audio, you do what you think is best, but there are a thousand ways to kill a cat and while it may be tempting to say one is better than another, such is the diversity of human psychoacoustic preferences that it's probably more appropriate to simply say that it's different......
Thanks for your great input and obvious excellence with this amp, much appreciated.
Cheers,
Hugh
Hi to all ,i have just recently joined in on this project (to many pages),looking for the parts list for the amplifier and any schematics for the latest release ,i also noticed that pcbs are being sourced from OZ more details please ,many thanks
Sam,
Have a gander at Group Buy #2, first non-sticky thread on the AKSA forum. All the details you need are there.
Post #59, here: http://www.diyaudio.com/forums/aksa/198170-group-buy-2-fetzilla-6.html
Hugh
Have a gander at Group Buy #2, first non-sticky thread on the AKSA forum. All the details you need are there.
Post #59, here: http://www.diyaudio.com/forums/aksa/198170-group-buy-2-fetzilla-6.html
Hugh
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