a333bt said:
Hi Bostjan
I have an SKpre, but, I am a bit slack in getting it up and going. Its purely because I am enjoying listening to music with my GB300D that I am not in a hurry ... oh well 🙂
The SKpre specs look exceptionally good, except IMO, for the input Z, which is 10K. Having said that, it still looks particularly impressive with only 2 transistors and a 50R directly in the signal path ...
Wrsto the Monstre, could you define what you call musical ...
thanks
KL
Hi KL,
you got me.
about term musical, i will try, it is only my perspective: non sterile, enjoy, not slow...
Did you tried AD815 preamp?
Bostjan
you got me.
about term musical, i will try, it is only my perspective: non sterile, enjoy, not slow...
Did you tried AD815 preamp?
Bostjan
a333bt said:
Hi Bostjan
I think I have the idea ... one more question ... how would you describe the GB150D's dynamics with C9 and with C9 removed
No, I haven't tried Carlos's AD815 preamp, yet, but the posts indicate that it is very good. It does have one fault, which is DC offset at the output. This may require the use of an input cap. 🙂
thanks
KL
KLe said:
Hi Bostjan
I think I have the idea ... one more question ... how would you describe the GB150D's dynamics with C9 and with C9 removed
No, I haven't tried Carlos's AD815 preamp, yet, but the posts indicate that it is very good. It does have one fault, which is DC offset at the output. This may require the use of an input cap. 🙂
thanks
KL
Hi KL,
i didnt have time to reply.
To answer you i check today with C9 and without C9 (wire instead).
there was no difference in dynamics, sound is better without C9, more details, more clean sound.
I tried with 2x BG NX HiQ 22uF anti-parallel connection. C9 add blur to sound, which i dont like.
You can try. Greg was in holidays till 17. december as i now, so i guess you can contact him.
regards, Bostjan
Thanks Bostjan
It sounds like w/o C9 is the way to go.
I wonder if larger than 47uF, say around 200uF would be better also?
thanks
KL
It sounds like w/o C9 is the way to go.
I wonder if larger than 47uF, say around 200uF would be better also?
thanks
KL
SKA150 impressions
Been running for a while now (about 3 weeks) and thoroughly enjoyable. I cannot pinpoint any weaknesses, except perhaps for a brightish treble on poorer recordings (about 1% of my CD collection-recordings from the 1940's etc).
On good recordings, everything sounds great. I am particularly pleased with the mids and bass, mids being well projected and bass being taut and detailed. Treble quality is excellent and on some of my discs (audiophile recordings...) there is a discernable "airyness". Staging is wide and deep with a wonderful presence. Detail retrieval is amazing and nothing seems to escape the amps. As others have pointed out, despite their detailed sound, the amps don't induce listener fatigue. Tweaks such as component changes etc don't come to mind, which says much about the prevailing quality. So yes, I am very impressed!
One final note: I have used LM3875, LM3886 and the 3886/386 based amps. These gave a good performance but had a tendency toward brightness; Mids tended to be grey relative to the SKA. Bass was detailed but thinner. I have relegated my chip-amps to the parts bin.
FWIW, the rest of the system is:
1. Theta Data III drive, Wydeye balanced digital cable (which is marginally better than the Madrigal Fat boy)
2. Theta Gen Va DAC (highly modified with ultra low noise ALW (Andy Weekes) power supplies, parallel PCM63K's and extensive digital power supply/clock mods), Van den Hul the Second Balanced cable.
3. Carlosfm's implementation of the AD815, but using Rudi's 2604 based DC servo and layout. Replacing my old pre (627 with BUF634) with the AD815 was one of the best upgrades I've had in my system.
4. The balanced to single end converters used in the pre are THAT1200, the best I've heard and far outperforming any competitors (SSM, Analog, etc). The THAT1200 was created in collaboration with Jensen.
5. The volume pot in the pre is a DACT, 100k stepped attenuator
6. Modified Royd Doublet speakers (new 30kg bases added, 5 9's silver internal wiring).
7. Speaker cable is a solid core, 28 gauge diy design
Happy listening!
Ryan
Been running for a while now (about 3 weeks) and thoroughly enjoyable. I cannot pinpoint any weaknesses, except perhaps for a brightish treble on poorer recordings (about 1% of my CD collection-recordings from the 1940's etc).
On good recordings, everything sounds great. I am particularly pleased with the mids and bass, mids being well projected and bass being taut and detailed. Treble quality is excellent and on some of my discs (audiophile recordings...) there is a discernable "airyness". Staging is wide and deep with a wonderful presence. Detail retrieval is amazing and nothing seems to escape the amps. As others have pointed out, despite their detailed sound, the amps don't induce listener fatigue. Tweaks such as component changes etc don't come to mind, which says much about the prevailing quality. So yes, I am very impressed!
One final note: I have used LM3875, LM3886 and the 3886/386 based amps. These gave a good performance but had a tendency toward brightness; Mids tended to be grey relative to the SKA. Bass was detailed but thinner. I have relegated my chip-amps to the parts bin.
FWIW, the rest of the system is:
1. Theta Data III drive, Wydeye balanced digital cable (which is marginally better than the Madrigal Fat boy)
2. Theta Gen Va DAC (highly modified with ultra low noise ALW (Andy Weekes) power supplies, parallel PCM63K's and extensive digital power supply/clock mods), Van den Hul the Second Balanced cable.
3. Carlosfm's implementation of the AD815, but using Rudi's 2604 based DC servo and layout. Replacing my old pre (627 with BUF634) with the AD815 was one of the best upgrades I've had in my system.
4. The balanced to single end converters used in the pre are THAT1200, the best I've heard and far outperforming any competitors (SSM, Analog, etc). The THAT1200 was created in collaboration with Jensen.
5. The volume pot in the pre is a DACT, 100k stepped attenuator
6. Modified Royd Doublet speakers (new 30kg bases added, 5 9's silver internal wiring).
7. Speaker cable is a solid core, 28 gauge diy design
Happy listening!
Ryan
Wait until you try the zener mod - if you think it's good now, that takes it to another level.
You have an impressive array of gear there.
You have an impressive array of gear there.
Hello Hifiddle,
Yeah, I forgot to mention that the zener mod is in already! The boards are standard otherwise, no magic components. Power supply is 25,000uF per rail, so 50,000uF per channel and I've built it as dual mono, each channel with its own 300VA transformer, 35V AC.
Mods I might try are:
1. Replacing the diode bridge with fast soft recovery rectifiers
2. Snubbing the rectifiers with 100 ohm in series with 47nF caps (this mod has worked very well in other applications)
3. Adding 0.1ohm resistors between the caps (on the plus and minus rail)-A friend of mine reports excellent results on his (non SKA) amp
But I'd like to just listen for now! Any other mod ideas?
Ryan
Yeah, I forgot to mention that the zener mod is in already! The boards are standard otherwise, no magic components. Power supply is 25,000uF per rail, so 50,000uF per channel and I've built it as dual mono, each channel with its own 300VA transformer, 35V AC.
Mods I might try are:
1. Replacing the diode bridge with fast soft recovery rectifiers
2. Snubbing the rectifiers with 100 ohm in series with 47nF caps (this mod has worked very well in other applications)
3. Adding 0.1ohm resistors between the caps (on the plus and minus rail)-A friend of mine reports excellent results on his (non SKA) amp
But I'd like to just listen for now! Any other mod ideas?
Ryan
Mine has only the zener mod done, I haven't substituted any 'premium' parts.
The next thing I might try is to DC couple the feedback loop by linking across C9. It is purported to remove a further veil - possibly due to capacitor dielectric absorption in the electrolytic.
Greg has advised that I need to be very sure of the thermal tracking to do this.
It was instantly better than my old Leach amp ( now binned).
The next thing I might try is to DC couple the feedback loop by linking across C9. It is purported to remove a further veil - possibly due to capacitor dielectric absorption in the electrolytic.
Greg has advised that I need to be very sure of the thermal tracking to do this.
It was instantly better than my old Leach amp ( now binned).
Hi,
i built also SKApre and after first listening, i can say that things went to another level: better everything about sound;
even cleaner, better - deeper soundstage, more details.
for volume control i use 10k blue Alps and i have plan to change with 10k relay attenuator.
regards, Bostjan
i built also SKApre and after first listening, i can say that things went to another level: better everything about sound;
even cleaner, better - deeper soundstage, more details.
for volume control i use 10k blue Alps and i have plan to change with 10k relay attenuator.
regards, Bostjan
Hi,
i built also SKApre and after first listening, i can say that things went to another level: better everything about sound;
even cleaner, better - deeper soundstage, more details.
for volume control i use 10k blue Alps and i have plan to change with 10k relay attenuator.
For PSU i use only trafo, regulators are already on PCB of SKApre.
regards, Bostjan🙂 🙂
i built also SKApre and after first listening, i can say that things went to another level: better everything about sound;
even cleaner, better - deeper soundstage, more details.
for volume control i use 10k blue Alps and i have plan to change with 10k relay attenuator.
For PSU i use only trafo, regulators are already on PCB of SKApre.
regards, Bostjan🙂 🙂
AndrewT said:
Hi Andrew,
SKA was very good without SKApre (i use pasive 10k pot), but now it is even better.😀
SKApre is in same chasis - box as SKA, (i like more less cables).
Later i will improve some critical components and make double power supply for SKA.
regards, Bostjan
Hi,
thanks.
10k passive was probably upsetting all the source/receiver conditions and introducing unintended filtering.
thanks.
10k passive was probably upsetting all the source/receiver conditions and introducing unintended filtering.
wher (how) to buy ska pcb?
hi,
I'm wondering how to buy ska pcb, is it still available?
Greg's site isn't accessible by me.
many tks for any information.
best rgds,
hi,
I'm wondering how to buy ska pcb, is it still available?
Greg's site isn't accessible by me.
many tks for any information.
best rgds,
Hi all!
Are the schematics of this amp available anywhere?
I'd like to stydy it to try to get an understanding of this amps unique points.
Regards
Are the schematics of this amp available anywhere?
I'd like to stydy it to try to get an understanding of this amps unique points.
Regards
Hi,
no Greg B wants to protect his intellectual property.
There are some titbits in the construction thread.
no Greg B wants to protect his intellectual property.
There are some titbits in the construction thread.
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