macka said:
ShinOBIWAN said:
Probably startup condition. If the bootstrap caps are too large
and have too slow corner frequency there may be a momentary
over current condition on the OP MOS devices or elsewhere. It
depends how everything ramps up.
Since you are doing ongoing R & D for Mr Ball I suggest you talk
to the man and get the fix.
Cheers,
Terry
Terry Demol said:
Greg has suggested that for the GB150 47uf is safe for C4 and C5, 10uf is standard and 100uf appears to work OK for me but I quote "100uf should be OK". I'm going to back my value down to 47uf when I get the opportunity as a safety precaution.
Hi carlosfmcarlosfm said:I feel that the 1nF cap from input to ground is (at least in part) responsible for this. Those of you who arewith the amp, try reducing this cap for something around 200pF.
No ceramics, please.
You might be right
You know there it isn't much missing, because, there is plenty of sparkle there, but, we are looking for absolute highest possible results, aren't we 😀 I have to say that this is an extremely nice amp 
Also, Greg quoted the following in a post on another site
This amp has nine lives..it still goes!
I have the Panasonic Fc 220 uf 35 volt on the feeback postion to ground and the BG N series 20uf (super E topology).
It is far more neutral than prior original parts.
Hugh,
Thanks for jumping in with a suggestion and a new approach.
I will look carefully as this idea!
Thanks again for all your posts.
Macka
I have the Panasonic Fc 220 uf 35 volt on the feeback postion to ground and the BG N series 20uf (super E topology).
It is far more neutral than prior original parts.
Hugh,
Thanks for jumping in with a suggestion and a new approach.
I will look carefully as this idea!
Thanks again for all your posts.
Macka
Listening impressions
I hate to keep harping and know I sound like a grump BUT I am still waiting for listening impressions.
It seems quite a number of people have now built this amp but precious few are prepared to come forward with listening impressions.
I support the concept that new amps need to bed down and their parts run in before they sound their best. This seems to be the excuse being used BUT contrary to actually allowing this to happen everyone seems to be busy changing parts types and values all over the place, often with no sound basis or even understanding of the design.
Given the amps aren't run in enough to provide a listening opinion how can there be any decent basis for comparing mods??
Now I fear we will rarely ever get any listening opinions as all we can get are impressions of modded amps with flavours that suit various personal tastes and all second guessing the original design.
So where are we?
BTW blaming a 125KHz roll-off for "lack of treble sparkle" is quaint!
Cheers,
I hate to keep harping and know I sound like a grump BUT I am still waiting for listening impressions.
It seems quite a number of people have now built this amp but precious few are prepared to come forward with listening impressions.
I support the concept that new amps need to bed down and their parts run in before they sound their best. This seems to be the excuse being used BUT contrary to actually allowing this to happen everyone seems to be busy changing parts types and values all over the place, often with no sound basis or even understanding of the design.
Given the amps aren't run in enough to provide a listening opinion how can there be any decent basis for comparing mods??
Now I fear we will rarely ever get any listening opinions as all we can get are impressions of modded amps with flavours that suit various personal tastes and all second guessing the original design.
So where are we?
BTW blaming a 125KHz roll-off for "lack of treble sparkle" is quaint!
Cheers,
Re: Listening impressions
It sounds like your looking for answers that only you yourself can provide. Subjective listening impressions are fine but coming here with 'there aren't many listening impressions' and then complaining about it won't still won't help you come to any real conclusions. There could be another 10 members that each submit a 1000 word essay on their own opinions and they could all be glowing or damning and it wouldn't matter until you'd heard one and made your own mind up.
KLe kindly collected up the opinions so far a few pages back:
http://www.diyaudio.com/forums/showthread.php?postid=855397#post855397
Non of those actually mean much BTW.
Greg has been very helpful in picking out the best area's for improvement and possible weakness's in the original component selection. If there aren't mistakes being made somewhere then we aren't trying hard enough! He's also come up with a way to further reduce PSRR and I will be trying that very soon.
I don't really believe in that rubbish about bedding in nor have I ever conclusively heard differences between cables that are competantly designed and intended for audio.
The only exception that I've encountered would be with the AKSA N+ which did definitely improve with run-in. Most folks believe the Blackgates to be the cause of this.
The folks that appear to be modding and posting on forums; Greg, me, KLe, Macka, Rellum have all submitted some sort of opinion on the sound of the original and now we're doing what DIY is all about and tinkering to try and improve on something that's already good and I do think its abundantly clear from the opinions so far that the amp in stand guise is already superb for the money. How many more opinions do you need?
I believe this will benefit everyone who owns an SKA as they will know what does and what doesn't improve the sound. Its all part of a slight evolution process.
So what are you looking for? Are you expecting a particular opinion to vindicate your own thoughts? I thought you'd bought a GB300? And if so, why not build it up, take a listen and then post a listening impression on here.
The amp is so smooth and clean sounding that I can imagine where the treble doesn't sparkle thing comes in. Its not your usual sibilant or shiney top end but controlled, clean and clear. The amp seems to be very even in its performance and nothing really stands out above any other element, so the treble isn't hyped nor are the mids or low end. I keep going back to my Roksan Kandy mkII and the SKA is clearly the better performer in all respects. In case you were wondering, the treble does sparkle nicely on decent recording and in my system.
hifryer said:
It sounds like your looking for answers that only you yourself can provide. Subjective listening impressions are fine but coming here with 'there aren't many listening impressions' and then complaining about it won't still won't help you come to any real conclusions. There could be another 10 members that each submit a 1000 word essay on their own opinions and they could all be glowing or damning and it wouldn't matter until you'd heard one and made your own mind up.
KLe kindly collected up the opinions so far a few pages back:
http://www.diyaudio.com/forums/showthread.php?postid=855397#post855397
Non of those actually mean much BTW.
Greg has been very helpful in picking out the best area's for improvement and possible weakness's in the original component selection. If there aren't mistakes being made somewhere then we aren't trying hard enough! He's also come up with a way to further reduce PSRR and I will be trying that very soon.
I don't really believe in that rubbish about bedding in nor have I ever conclusively heard differences between cables that are competantly designed and intended for audio.
The only exception that I've encountered would be with the AKSA N+ which did definitely improve with run-in. Most folks believe the Blackgates to be the cause of this.
The folks that appear to be modding and posting on forums; Greg, me, KLe, Macka, Rellum have all submitted some sort of opinion on the sound of the original and now we're doing what DIY is all about and tinkering to try and improve on something that's already good and I do think its abundantly clear from the opinions so far that the amp in stand guise is already superb for the money. How many more opinions do you need?
I believe this will benefit everyone who owns an SKA as they will know what does and what doesn't improve the sound. Its all part of a slight evolution process.
So what are you looking for? Are you expecting a particular opinion to vindicate your own thoughts? I thought you'd bought a GB300? And if so, why not build it up, take a listen and then post a listening impression on here.
The amp is so smooth and clean sounding that I can imagine where the treble doesn't sparkle thing comes in. Its not your usual sibilant or shiney top end but controlled, clean and clear. The amp seems to be very even in its performance and nothing really stands out above any other element, so the treble isn't hyped nor are the mids or low end. I keep going back to my Roksan Kandy mkII and the SKA is clearly the better performer in all respects. In case you were wondering, the treble does sparkle nicely on decent recording and in my system.
Re: Listening impressions
I don't think you understand where "we" are at.
Most of us who have made the effort to actually build it are now familiar with it and are looking for refinement and to try options assuggested by the designer Greg Ball.
As Greg Ball advised me in his email, the SKA is equiped with various options for experiementation and so this is exactly what I am doing.
Greg is at the moment encouraging me to try alternative parts types so I am doing this. In Greg's words the SKA is a work in progress.
So it would seem you are out of touch with what is going on.
No, this is not AudioKarma or a Stereophile download page.
If you like reading lots of glowing reviews, please leave quietly and go elsewhere.
I don't think you understand where "we" are at.
Most of us who have made the effort to actually build it are now familiar with it and are looking for refinement and to try options assuggested by the designer Greg Ball.
As Greg Ball advised me in his email, the SKA is equiped with various options for experiementation and so this is exactly what I am doing.
Greg is at the moment encouraging me to try alternative parts types so I am doing this. In Greg's words the SKA is a work in progress.
So it would seem you are out of touch with what is going on.
No, this is not AudioKarma or a Stereophile download page.
If you like reading lots of glowing reviews, please leave quietly and go elsewhere.
hifryer said:
macka said:
Thanks.
What voltage rating are you using BTW? I've seen the BG N-HiQ in 22uf but only rated for 6.3v. I've mailed Greg to ask if this is safe before doing anything.
I'm thinking of swapping out R2, 3, 4 and 24(1W) from metal film to Audionote tantalum resistors:
http://www.hificollective.co.uk/components/resistors.html
Looks to be going to cost around £45 to mod all 4 GB150's.
http://www.hificollective.co.uk/components/resistors.html
Looks to be going to cost around £45 to mod all 4 GB150's.
AKSA said:
Hugh
You are right the signals are effectively in phase...the danger of making post at bed time.
But I still see your proposition of using a 0,22 uF bootstrap capacitor as a bad idea , because at 50 hZ the capacitor will have a impedance of ~ 15 KOhms and this impedance in conjunction with the resistor that connect the base of the follower to the rail , will make a voltage divider, so the bootstrapped effect will be diminished specially at low frequencies with the consequent increase in distortion and loss of PSRR .
Cheers.
New Listening
I have finally installed the GB150D in my system. For reference, I have listened to a large number of amps through the years and a number of them would make me happy (many would not) as their differences are, for me, subtle and the impact of my listening room and speakers are a much larger effect.
In one word, the GB150D is, for me, precise. Imaging is excellent with instruments well placed and stable, i.e. precise. As ShinOBIWAN pointed out, instrument sizes are natural and not out of proportion. The precise characterization carries over to attack and decay of sounds as well. As others have noted the dynamics are superb. One thing I particularly enjoyed is the amps ability to reveal subtle detail in very dynamic passages. I am particularly fond of Beethovens Ninth, and there is a lot of subltle detail in the highly dynamic 4th movement that you may not be aware of if you have not heard a live performance. I use the word precise in the sense of being correct, with little error, not to imply clinical or sterile.
I am not too good at assigning words to what I hear, so I will sum it up by saying the sound is Precise and Correct to my ear. Do not know what those words will mean to you, but they mean to me that I like the GB150D.
Bill
I have finally installed the GB150D in my system. For reference, I have listened to a large number of amps through the years and a number of them would make me happy (many would not) as their differences are, for me, subtle and the impact of my listening room and speakers are a much larger effect.
In one word, the GB150D is, for me, precise. Imaging is excellent with instruments well placed and stable, i.e. precise. As ShinOBIWAN pointed out, instrument sizes are natural and not out of proportion. The precise characterization carries over to attack and decay of sounds as well. As others have noted the dynamics are superb. One thing I particularly enjoyed is the amps ability to reveal subtle detail in very dynamic passages. I am particularly fond of Beethovens Ninth, and there is a lot of subltle detail in the highly dynamic 4th movement that you may not be aware of if you have not heard a live performance. I use the word precise in the sense of being correct, with little error, not to imply clinical or sterile.
I am not too good at assigning words to what I hear, so I will sum it up by saying the sound is Precise and Correct to my ear. Do not know what those words will mean to you, but they mean to me that I like the GB150D.
Bill
Re: New Listening
Nice summation of the GB150 Bill,
I'd have to completely agree with you and like the way your described the dynamics and correctness of the sound, I was reading it and was thinking 'hey yep mine does that too' and 'that sounds like we're talking about the same thing'.
I think its clear that from all the opinions gathered so far, the SKA is a pretty special amp for the money, actually its pretty special full stop.
Glad that Greg made this possible, its been enlightening and continues to improve with the mods being suggested 🙂
wwood said:
Nice summation of the GB150 Bill,
I'd have to completely agree with you and like the way your described the dynamics and correctness of the sound, I was reading it and was thinking 'hey yep mine does that too' and 'that sounds like we're talking about the same thing'.
I think its clear that from all the opinions gathered so far, the SKA is a pretty special amp for the money, actually its pretty special full stop.
Glad that Greg made this possible, its been enlightening and continues to improve with the mods being suggested 🙂
macka said:
OK cheers Macka,
I'll wait to hear back from Greg on whether the 6.3v Nx-HiQ are rated high enough to be used on bootstrap and feedback.
listening impressions
Hi shinOBIWAN,
No, I'm not expecting any answers! So sorry for expecting to read listening impressions in a listening impressions thread!! ;-)
You wrote a good review. Others have promised. Is there a problem in wondering where these reviews are? Hopefully some will appear soon 🙂
You seem unduly defensive?
However, I did manage to squeeze some new useful listening comment from you!! ;-)
How does the 300 compare to the 150??
cheers,
Hi shinOBIWAN,
No, I'm not expecting any answers! So sorry for expecting to read listening impressions in a listening impressions thread!! ;-)
You wrote a good review. Others have promised. Is there a problem in wondering where these reviews are? Hopefully some will appear soon 🙂
You seem unduly defensive?
However, I did manage to squeeze some new useful listening comment from you!! ;-)
'
How does the 300 compare to the 150??
cheers,
Re: listening impressions
Give it time and I expect more will pop up. Wwood just did that, like everything there's only so much time for indulging in hobbies and forums.
I don't think you can reasonably demand that folks post impressions. When they feel the time is right, they'll do so I expect.
Oh, and like virtually every thread on DIYA, the topic does sometimes wander. Its still all SKA related just not purely listening impressions.
Defensive, maybe.
It sounds more like you just after every post in this thread to be a listening impression. On top of that you suggested that modding is being done in uncontrolled ways, with no knowledge of the design and without aquinting one's self with the original component selection and package.
I raised an eyebrow to all of that because:
A) Not everyone is going to be a*sed about posting a review, I'm sure they'll be people that have said they'll post a review but never actually get around to it. There's also impressions from KLe, wwood, myself, Macka, Rellum, Hubert that I know of so there enough to make a decision about the amp. More just seems like further confirmation and bedtime reading. Like I already said, you've bought the GB300 so you'll get to hear it soon enough and then the opinions won't matter 😉
B) Everyone that's trying the mods (that I know of) is already familiar with the original SKA, I have even left 2 modules as standard so I can compare the differences in stereo, can't say fairer than that. So the modding can only be productive or at least a learning experience. Its looking to be yielding an even better amp too.
C) Greg has been in touch with most of us the whole time, guiding and suggesting the best area's to tackle as well as idea's to further the design as a whole. I guess that was harder to ascertain since he can't post on here.
The 300 sounds like the 150 but I haven't compared directly. The bass is revelatory and the dynamics are huge but with 250w that's to be expected. TBH I've only had it running very briefly and instead have been playing with the GB150 and the mods. I'm waiting on some cases being delivered from Italy, so until then I'm holding off doing anything serious with them.
hifryer said:
Give it time and I expect more will pop up. Wwood just did that, like everything there's only so much time for indulging in hobbies and forums.
I don't think you can reasonably demand that folks post impressions. When they feel the time is right, they'll do so I expect.
Oh, and like virtually every thread on DIYA, the topic does sometimes wander. Its still all SKA related just not purely listening impressions.
Defensive, maybe.
It sounds more like you just after every post in this thread to be a listening impression. On top of that you suggested that modding is being done in uncontrolled ways, with no knowledge of the design and without aquinting one's self with the original component selection and package.
I raised an eyebrow to all of that because:
A) Not everyone is going to be a*sed about posting a review, I'm sure they'll be people that have said they'll post a review but never actually get around to it. There's also impressions from KLe, wwood, myself, Macka, Rellum, Hubert that I know of so there enough to make a decision about the amp. More just seems like further confirmation and bedtime reading. Like I already said, you've bought the GB300 so you'll get to hear it soon enough and then the opinions won't matter 😉
B) Everyone that's trying the mods (that I know of) is already familiar with the original SKA, I have even left 2 modules as standard so I can compare the differences in stereo, can't say fairer than that. So the modding can only be productive or at least a learning experience. Its looking to be yielding an even better amp too.
C) Greg has been in touch with most of us the whole time, guiding and suggesting the best area's to tackle as well as idea's to further the design as a whole. I guess that was harder to ascertain since he can't post on here.
The 300 sounds like the 150 but I haven't compared directly. The bass is revelatory and the dynamics are huge but with 250w that's to be expected. TBH I've only had it running very briefly and instead have been playing with the GB150 and the mods. I'm waiting on some cases being delivered from Italy, so until then I'm holding off doing anything serious with them.
I supose we could always set up an email stream so we can communicate and discuss our impressions and modifications.
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