Gabdx1
The only difference was the decay of notes, it was more detailed you could hear the microphones distortions of old recordings just bellow the high frequency : like 1k - 3khz around that.
so you hear some difference
But the amp has already lot of details... so I would not suggest doing any DC coupled without a dc servo. you dont want 28 X amplified DC current
I suggest an output fuse made from low temperature co-efficient resistance ( constantan ) wire soldered in place.
You will need to thermally link the q1-q2, and q3-q4 for around +- 5mv dc output... With the cap in you can get +-0.1 mv of dc !!!!!
what's wrong with 5mV ?
The sound itself doesnt change at all with dc couple... so just put a good cap there and don't worry about it and biaised people who say a capacitor in the feedback is bad...
But you said at the begining you could hear a difference . . .
I wonder why you say that people who disagree with you are biased.
I spoke to a guy who makes and sells audiophile film caps and he told me there is no cap that exists that sounds like no cap - and you are looking for an electrolytic that sounds invisible ?
For me, when you have removed the last cap from the signal path and use only high quality, low noise resistors and have a very very low noise power supply - then it becomes possible to approach true high fidelity - then when you re-introduce one cheap resistor or one cap, then you really know how it changes the sound.
That's my opinion but from what you say I guess we don't agree 100% on this
The only difference was the decay of notes, it was more detailed you could hear the microphones distortions of old recordings just bellow the high frequency : like 1k - 3khz around that.
so you hear some difference
But the amp has already lot of details... so I would not suggest doing any DC coupled without a dc servo. you dont want 28 X amplified DC current
I suggest an output fuse made from low temperature co-efficient resistance ( constantan ) wire soldered in place.
You will need to thermally link the q1-q2, and q3-q4 for around +- 5mv dc output... With the cap in you can get +-0.1 mv of dc !!!!!
what's wrong with 5mV ?
The sound itself doesnt change at all with dc couple... so just put a good cap there and don't worry about it and biaised people who say a capacitor in the feedback is bad...
But you said at the begining you could hear a difference . . .
I wonder why you say that people who disagree with you are biased.
I spoke to a guy who makes and sells audiophile film caps and he told me there is no cap that exists that sounds like no cap - and you are looking for an electrolytic that sounds invisible ?
For me, when you have removed the last cap from the signal path and use only high quality, low noise resistors and have a very very low noise power supply - then it becomes possible to approach true high fidelity - then when you re-introduce one cheap resistor or one cap, then you really know how it changes the sound.
That's my opinion but from what you say I guess we don't agree 100% on this
From my experience removing caps from the signal path is worthwile under the circumstances that the other parts of the chain are top notch. The chain includes the person(s) who are listening.
There have been some discussion earlier on in Electronic World with measurments on caps and caps do introduce distortion. If you can hear this is? I guess some of us can, thus it is rather meaningsless to start a debate on the topic and try to persuede one another who´s right.
Only double blind tests make sense to me. It´s clear that our hearing differs and that we can be more aware of small differences if we practice to hear them. Consider small children who get their senses for music while living in a stimulating environment at earlly ages perhaps 4-7 years of age when there is a clear window of high sensivity to musical training. The likelyhood that they will suffer later on if they hear someone singing out of tune is higher than children not benifitting from such stimulation (of course one can´t disregard heredity).
This sensitivity declines and unfortunately at at ages about 60 years or so there is a decline in some of the brain´s structure to some aspects of musicallity (maybe) mainly the ability to remember tunes, and this mean to some extent how we can explain that our ability to remember names gets worse.
You may argue that I mix up being skilled at music with the ability by a person to distinguish small differences in the reproduction of music and perhaps I do. But I believe they are closely related and that they have something to do with self-confidence, attention and training.
Of course we can´t disregard the possibility that we hear what we expect to hear. If we tweak an amp for a week or so we very much want a positive result and just therefore might hear it without any objective result at all.
But doing large changes to the room acoustics in our listening room will very likely make a real difference and will be heard even by people with a "normal perception" if they are presented with the changes in a closly spaced time. But probably, if we expand the time between listening sessions, only a few individuals are able to describe the difference (naturally visual cues make sense to).
There are only a few people that can say how the sound has changed in my very revealing system with time and efforts by me and there are agreement among those of us who can. Others say it sounds "as usual". Who are right? Maybe both groups in a subjective sense....
There have been some discussion earlier on in Electronic World with measurments on caps and caps do introduce distortion. If you can hear this is? I guess some of us can, thus it is rather meaningsless to start a debate on the topic and try to persuede one another who´s right.
Only double blind tests make sense to me. It´s clear that our hearing differs and that we can be more aware of small differences if we practice to hear them. Consider small children who get their senses for music while living in a stimulating environment at earlly ages perhaps 4-7 years of age when there is a clear window of high sensivity to musical training. The likelyhood that they will suffer later on if they hear someone singing out of tune is higher than children not benifitting from such stimulation (of course one can´t disregard heredity).
This sensitivity declines and unfortunately at at ages about 60 years or so there is a decline in some of the brain´s structure to some aspects of musicallity (maybe) mainly the ability to remember tunes, and this mean to some extent how we can explain that our ability to remember names gets worse.
You may argue that I mix up being skilled at music with the ability by a person to distinguish small differences in the reproduction of music and perhaps I do. But I believe they are closely related and that they have something to do with self-confidence, attention and training.
Of course we can´t disregard the possibility that we hear what we expect to hear. If we tweak an amp for a week or so we very much want a positive result and just therefore might hear it without any objective result at all.
But doing large changes to the room acoustics in our listening room will very likely make a real difference and will be heard even by people with a "normal perception" if they are presented with the changes in a closly spaced time. But probably, if we expand the time between listening sessions, only a few individuals are able to describe the difference (naturally visual cues make sense to).
There are only a few people that can say how the sound has changed in my very revealing system with time and efforts by me and there are agreement among those of us who can. Others say it sounds "as usual". Who are right? Maybe both groups in a subjective sense....
Mikelm,
You posted on another thread about the sound of the Zeus amp's main characteristic being fluidity. That amp uses transformers instead of caps in the signal path & no global feedback.
How does your SKA (with high global feedback) now compare in sound to the Zeus? Has it more forward presentation in the upper midrange (more apparent detail) as is considered the sound of global feedback amps?
Just trying to get a handle on the possible sonic influences of various configurations/devices!
You posted on another thread about the sound of the Zeus amp's main characteristic being fluidity. That amp uses transformers instead of caps in the signal path & no global feedback.
How does your SKA (with high global feedback) now compare in sound to the Zeus? Has it more forward presentation in the upper midrange (more apparent detail) as is considered the sound of global feedback amps?
Just trying to get a handle on the possible sonic influences of various configurations/devices!
jkeny said:
The SKA in the configuration I have has more actual detail and as I alluded to before elsewhere whether or not this is desirable perhaps depends on several different factors.
This amp is very transparent you hear so much of what is happening in recordings so if it is not a good recording you hear all about it. Equally so with the source you are using. Hard to say how much or what the amp may be adding
But when I say detail it is very different from the kind of exaggerated rough sounding detail that many solid state amps create.
The plus side is that on a some recording it sounds quite sublime with very very fine textures conveyed including the ambience of recordings - like u can actually hear the texture of the air and even cymbals begin to sound vaguely realistic - hehe
However on other recordings you can almost hear too much detail and perhaps these recordings will sound better with an amp without feedback that is a bit more sympathetic and smooths things out to a small degree.
But on good recordings - perhaps when the mics are not so close and / or where some natural ambience is included I think I would miss some of the rich and fine texture that the SKA can resolve.
If you read the SKA constructors thread I have posted what I have done recently with my amp.
The zeus I built is in the UK at present but I have a plan to build another one do do this very comparison - just waiting for one or two components.
For me the real key ingredient is extremely low electrical noise throughout the entire reproduction chain - this in itself will allow the fine low level details to be revealed and make the sound very smooth & natural. That achieved, for me it is then just a matter of personal preference and or type of recordings as to whether NFB or FB amps are preferred.
mike
Thanks for your reply - educational, as usual.
I agree with you about the low electrical noise being a key ingredient for this magic to appear. Both of these amps have excellent PSRR which goes a long way to explaining their exemplary performance.
Even with these high PSRR amps I guess careful design of low noise PS is beneficial but to what degree is it heard in both amps?
As I'm looking for as much realism in presentation of music, good or bad, my choice would be the SKA but as you said already this does depend on having a near perfect front end (and who does). It also depends on how much of my music library is badly recorded as to whether I could live with this realism long-term.
For DC protection of speakers, can you say how a constantan output fuse would be sized?
I agree with you about the low electrical noise being a key ingredient for this magic to appear. Both of these amps have excellent PSRR which goes a long way to explaining their exemplary performance.
Even with these high PSRR amps I guess careful design of low noise PS is beneficial but to what degree is it heard in both amps?
As I'm looking for as much realism in presentation of music, good or bad, my choice would be the SKA but as you said already this does depend on having a near perfect front end (and who does). It also depends on how much of my music library is badly recorded as to whether I could live with this realism long-term.
For DC protection of speakers, can you say how a constantan output fuse would be sized?
hi mike,
Sorry if I said indirectly your biased, i am biased too by my sound system, and my ears
I just wanted to warn people about this:
- possible long term damage to speakers ( 50 mv +)
- possible blow fuses
- possible speaker damage in case of failure of circuit components
It just make it worse in case of an accident.
For example if you remove one wire of the rca , MY amp goes into pop noise and blow the fuse.
If i switch sources, i can get over 100 mV of DC so i need to adjust it I blow some fuse also switching sources with lots of DC.
Finally the DC couple thing I did was to improve the bass, make it more but it made NO difference there, also the detail of decay was better but the sound itself and dynamics didnt changed...
Keep in mind the difference will be bigger if you replace the Lelon cap, my caps was the best you can find and bypassed.
Now that I am thinking about it I wouldnt done the DC thing if i had known the little difference it made.
Everyone is free If you want try it.
My Ska is tweaked a lot : nichicon everywhere, PRP, tantalums, it already sounds perfect before and after the DC
Sorry if I said indirectly your biased, i am biased too by my sound system, and my ears
I just wanted to warn people about this:
- possible long term damage to speakers ( 50 mv +)
- possible blow fuses
- possible speaker damage in case of failure of circuit components
It just make it worse in case of an accident.
For example if you remove one wire of the rca , MY amp goes into pop noise and blow the fuse.
If i switch sources, i can get over 100 mV of DC so i need to adjust it I blow some fuse also switching sources with lots of DC.
Finally the DC couple thing I did was to improve the bass, make it more but it made NO difference there, also the detail of decay was better but the sound itself and dynamics didnt changed...
Keep in mind the difference will be bigger if you replace the Lelon cap, my caps was the best you can find and bypassed.
Now that I am thinking about it I wouldnt done the DC thing if i had known the little difference it made.
Everyone is free
If you want try it.My Ska is tweaked a lot : nichicon everywhere, PRP, tantalums, it already sounds perfect before and after the DC
I found this site for calculating speaker fuse requirements http://www.barryrudolph.com/greg/fuse.html from this I read a current rating of~2.0 Amps needed for 8ohm speakers on a 100 watt amp (400 watt RMS?)
Does this seem appropriate?
I have access to some old stocks of wire in the electrical dept of college - 26 SWG (0.46mm) Eureka wire & Tophet C wire. Both of these are in the same category as constantan - low temperature-coefficient of resistance.
So now I just have to match wire sizing to current capability.
I take it this speaker fuse just prevents DC on the speaker which could blow the speaker cone coil/ former - something I'm sensitive to as I blew my Rogers LS3/5a speakers with a DC connection & the coil heat deformed the former - I rebuilt them satisfactorily, however with new coil/formers.
Does this seem appropriate?
I have access to some old stocks of wire in the electrical dept of college - 26 SWG (0.46mm) Eureka wire & Tophet C wire. Both of these are in the same category as constantan - low temperature-coefficient of resistance.
So now I just have to match wire sizing to current capability.
I take it this speaker fuse just prevents DC on the speaker which could blow the speaker cone coil/ former - something I'm sensitive to as I blew my Rogers LS3/5a speakers with a DC connection & the coil heat deformed the former - I rebuilt them satisfactorily, however with new coil/formers.
a pair of F fuses on the supply rails achieves the same protection and can run a smaller value fuse since each gets a cool down period during the rectified AC signal that passes.
Quasi recommends fuse rating of half of maximum Irms into your speaker load. Using this indicates F1.6A or F2A for 100W into 8r0.
I suspect from my full power testing into resistive loads that the fuse can be even smaller and still not suffer nuisance blowing.
Quasi recommends fuse rating of half of maximum Irms into your speaker load. Using this indicates F1.6A or F2A for 100W into 8r0.
I suspect from my full power testing into resistive loads that the fuse can be even smaller and still not suffer nuisance blowing.
Commercial amp or GB150kit?
I'm hunting for an amp to partner my Usher BE-718s. Old-timers will remember I was considering the GB-150s to partner my Dynaudio BM6, but I'm happy running those off a paralleled LM3886, which drives them to high levels for nearfield monitoring, without running out of current (the Dynes are 4 ohm, 86 db/w and I sit about a meter away from them).
The Ushers very good speakers, and are fairly revealing (not in a very harsh way) of the quality of upstream equipment. Plus, they're 85 db/W as per John Atkinson's measurements, so they need voltage, but they're not particularly demanding of high current. So far, I'm using a single LM3886 per side with lots of capacitance to drive the amps, and though the sound is acceptable it runs out of steam early due to the low sensitivity, and is a little 'cold' and 'hard', probably due to the chip itself.
I'm looking out for an amp that is natural and neutral, with lots of voltage drive. My choices were commercial amps in the <$2000 range, or the GB150 kit from Greg. I don't mind a DIY kit, I love fiddling around but need it to be somewhat plug and play.
Would any of you have had a chance to compare your (or anyone else's) GB150s to commercial equipment and if yes, what were your impressions? I'm currently considering the Cambridge Audio 840AV2, the Vincent SP331-MK, Usher R1.5 and the Odyssey Stratos as alternatives. The GB150D kit is 1/3rd the price, but I'm not really looking to save money, only to get as good a sound as I possibly can. Of course the 840 and the 331 are frontrunners due to the 150 w/ch ratings, the Ushers and Odyssey are lower output and may not present a step up from the 3886.
Thanks for your opinions and help.
I'm hunting for an amp to partner my Usher BE-718s. Old-timers will remember I was considering the GB-150s to partner my Dynaudio BM6, but I'm happy running those off a paralleled LM3886, which drives them to high levels for nearfield monitoring, without running out of current (the Dynes are 4 ohm, 86 db/w and I sit about a meter away from them).
The Ushers very good speakers, and are fairly revealing (not in a very harsh way) of the quality of upstream equipment. Plus, they're 85 db/W as per John Atkinson's measurements, so they need voltage, but they're not particularly demanding of high current. So far, I'm using a single LM3886 per side with lots of capacitance to drive the amps, and though the sound is acceptable it runs out of steam early due to the low sensitivity, and is a little 'cold' and 'hard', probably due to the chip itself.
I'm looking out for an amp that is natural and neutral, with lots of voltage drive. My choices were commercial amps in the <$2000 range, or the GB150 kit from Greg. I don't mind a DIY kit, I love fiddling around but need it to be somewhat plug and play.
Would any of you have had a chance to compare your (or anyone else's) GB150s to commercial equipment and if yes, what were your impressions? I'm currently considering the Cambridge Audio 840AV2, the Vincent SP331-MK, Usher R1.5 and the Odyssey Stratos as alternatives. The GB150D kit is 1/3rd the price, but I'm not really looking to save money, only to get as good a sound as I possibly can. Of course the 840 and the 331 are frontrunners due to the 150 w/ch ratings, the Ushers and Odyssey are lower output and may not present a step up from the 3886.
Thanks for your opinions and help.
I think SKA audio can build you a 300 watts amplifier in the price range (2k). GB300 -- Greg's amps have lots of gain and very good for like 85 DB sensitivity speakers.
IMO it really depends on the speakers your plugging the amp - and the preamp, foreplay tube amps are very good, optivol with skapre also...
IMO ska beats lots of amps in the neutrality, natural high and midrange, lack of digital sound.
Because i think* they are neutral the bass is somewhat just in the middle, its just very detailed... some like some don't
I remember quite well the cam 840av2 - its clean - multitexture of the sound - but IMO you can hear electronics... and the sound stage is not as good... still there is strong points to the cambridge, its well priced. Since i have the ska the only amp that compares to it is the creek destiny - but i do not have the same speakers... my ska is on DIY open baffle and the destiny was listened with harbeths - very different speakers.
I hope this helps.... also just to let you know i can build you a modified gb300 or gb150, but my price would probably be higher than Greg's.
IMO it really depends on the speakers your plugging the amp - and the preamp, foreplay tube amps are very good, optivol with skapre also...
IMO ska beats lots of amps in the neutrality, natural high and midrange, lack of digital sound.
Because i think* they are neutral the bass is somewhat just in the middle, its just very detailed... some like some don't
I remember quite well the cam 840av2 - its clean - multitexture of the sound - but IMO you can hear electronics... and the sound stage is not as good... still there is strong points to the cambridge, its well priced. Since i have the ska the only amp that compares to it is the creek destiny - but i do not have the same speakers... my ska is on DIY open baffle and the destiny was listened with harbeths - very different speakers.
I hope this helps.... also just to let you know i can build you a modified gb300 or gb150, but my price would probably be higher than Greg's.
Its based on shopping experience listened to it around 1 hour (at planetofsound on bank street = very good audio shop, the salesman is very friendly and his systems are the best i have heared so far : Simons Yorke ? record player, harbeth speakers, audio research amps... the match is like heaven , I went at Codell audio in Montreal and I didnt had a good experience.
Last year i was looking for cd-amp-speakers just under 10k
I finaly ended up with diy speakers, sony player, and vp845, bottlehead gears (very good) did all kind of modifications.... and now I have the ska with Sound-noise of around 100 db it is perfect for paper drivers with 100 = no hum at all after I cured the ground loop issue.
My cd players include, blu-ray, sony707, 610es (broken now by me), and dbx dx5, that ill modify to death : dexa regulator, clock, independant passive iv with discrete // class A output etc. I just LOVE to play with electronics.
(at planetofsound on bank street = very good audio shop, the salesman is very friendly and his systems are the best i have heared so far : Simons Yorke ? record player, harbeth speakers, audio research amps... the match is like heaven , I went at Codell audio in Montreal and I didnt had a good experience. Last year i was looking for cd-amp-speakers just under 10k
I finaly ended up with diy speakers, sony player, and vp845, bottlehead gears (very good) did all kind of modifications.... and now I have the ska with Sound-noise of around 100 db it is perfect for paper drivers with 100 = no hum at all after I cured the ground loop issue.
My cd players include, blu-ray, sony707, 610es (broken now by me), and dbx dx5, that ill modify to death : dexa regulator, clock, independant passive iv with discrete // class A output etc. I just LOVE to play with electronics.
Cool, nice to meet you Chris.
I am a French-Canadian, and I don't pretend to know anything about electronics or stereo in general. My background is more musician and music lover. But since my youngest age I wanted to know how things are made and have a passion for listening music, I used to sit on the carpet near the speakers with a never-ending awe.
My audio philosophy:
When you chose a stereo it’s like choosing an instrument, none sound the same. Many* people don't hear the difference between different sounds, accuracy, pitch, clarity, fundamentals, harmonics... - the ear needs to be trained. Also your music taste will influence your pick of components. If there was an *accurate* way to reproduce sound at all the best studio in the world would be sitting same equipment
The ear is also easy fooled and this is what I try to avoid
: hifi that crystallize sound and make it irritant and lifeless, hifi that diminish the dynamic range and pretends to have lots of details, hifi that just pretends..., low-fi that pretends to sound better than hifi, people with no education in music rock witch is mostly distortion) judging what sounds good. I can think of many other things : but to finish : racial differences, like chineses or japanese don't have the same sound preference, because the ear is trained or adapted ( evolution) to hear better in some frequency of the native language.
What I am looking for and nearly reached : flat response in the room (35 - 18khertz), life-like dynamics - absence of digital/tube artifacts - purity of the output sound wave for sine wave, magic : 3d - event transportation - realism.
I am a French-Canadian, and I don't pretend to know anything about electronics or stereo in general. My background is more musician and music lover. But since my youngest age I wanted to know how things are made and have a passion for listening music, I used to sit on the carpet near the speakers with a never-ending awe.
My audio philosophy:
When you chose a stereo it’s like choosing an instrument, none sound the same. Many* people don't hear the difference between different sounds, accuracy, pitch, clarity, fundamentals, harmonics... - the ear needs to be trained. Also your music taste will influence your pick of components. If there was an *accurate* way to reproduce sound at all the best studio in the world would be sitting same equipment
The ear is also easy fooled and this is what I try to avoid
: hifi that crystallize sound and make it irritant and lifeless, hifi that diminish the dynamic range and pretends to have lots of details, hifi that just pretends..., low-fi that pretends to sound better than hifi, people with no education in music
rock witch is mostly distortion) judging what sounds good. I can think of many other things : but to finish : racial differences, like chineses or japanese don't have the same sound preference, because the ear is trained or adapted ( evolution) to hear better in some frequency of the native language.What I am looking for and nearly reached : flat response in the room (35 - 18khertz), life-like dynamics - absence of digital/tube artifacts - purity of the output sound wave for sine wave, magic : 3d - event transportation - realism.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.