float said:
They sound like typical Big Box systems. So, too, did Norman Crowhurst's designs, so did Williamson's fifty years ago. It goes with the territory since Self, Crowhurst, and Williamson were design consultants to the Big Box manufacturers. Then, as now, these guys want impressive looking specs to make the marketing dept. happy. Doesn't mean that they don't know any better, but they aren't going to blow their careers by blowing the whistle on the numbers game. (Except for Williamson who readily admitted that his design sucked because it used way too much feedback to force the numbers to spec good.)
You have to read between the lines, so to speak, and not take everything as "gospel", because it ain't. There's always a certain amount of "schmoozing" required if you want to keep on getting consulting fees. Guy's gotta pay the bills dontchaknow.
I don't agree with everything Self ever wrote, since he was wrong about the quasi-comp topology. Q-C may spec worse, but it sounds better than a full complementary. I tried it both ways, and Q-C definitely wins. At least so far as my preferences go.
hey Miles
The ska gb150 is my main system amp. Greg Ball definitely helped me a lot to optimize what I built. But I have other amps in the closet from previous times; I like building stuff.I have a P.Daniel a30 pcb's and schemo. Finding the right size heatsinks at an affordable price is an ongoing pursuit, anyone know of any in a dusty corner somewhere?
Miles, could you point me towards the amp design that you like using the bjt ?
The ska gb150 is my main system amp. Greg Ball definitely helped me a lot to optimize what I built. But I have other amps in the closet from previous times; I like building stuff.I have a P.Daniel a30 pcb's and schemo. Finding the right size heatsinks at an affordable price is an ongoing pursuit, anyone know of any in a dusty corner somewhere?
Miles, could you point me towards the amp design that you like using the bjt ?
re: topic
The following listening impressions are in 2 parts by necessity.
I've had a GB150 up and running for a few weeks which has been mated to a ESP P88 (1/2 of) connected to a 6922 valve "pre?" It adds some tube flavour, that's all, oh, and a bit of hum. It's had ample running time so here are my impressions.
Previous to the GB150 I was using Mauro Penasa's My_Ref (rev C) from Twisted Pear. The build was stock excluding a Auricap on the input. So Mauro's amp is what the impressions are compared to. I should note that I was extremely impressed by the little Mauro and if I hadn't wanted more drive (headroom) I'd still be using it.
Part 1.
In general the differences are better tonal balance in that it appears more even across the board, more coherent upper end, drive and control. The biggest plus however is all the minute details that were always there but are now more cohesive, the mids in particular. That's not to say these little details detract or demand your attention but more so that you aren't guessing anymore if you heard something. The added depth (imaging) is a big deal too. This is the first amp I've had (though not heard) that projects sound forward of the driver and into the room where locating a performer is as easy as listening. Blacks are black - the amp is quiet. Take the valves out of the equation and I can't hear anything with ear against the drivers.
With regard to negatives, well, there were a couple though by degree's they were slight – note that comment is past tense. The bass seemed lighter than Mauro's amp. Not lean just lighter. At the time I put this down to tighter control or perhaps because the amp has a black gate as the feedback cap, I don't know how much this could affect the sound and if so how long it may need to 'burn-in'. The treble too, seemed a little light-on. This was rationalized easily as the Mauro it quite hot up top and I was about ready to pad down the tweeter a notch or two. Sadly the brain was still getting signals that I was listening to the gear, not just the tunes.
Part 2.
After hours listening to the GB150 I began wondering what the weak link was and it was obviously the op-amp based pre (2134, 843 and even the 627, using a 15VDC regulated PS hooked to a 30VA tranny). You could argue it's the CDP but, your not allowed – besides its being addressed!
After knocking up a pair of SKpre modules and wiring them into the existing pre case they were tested, DC nulled and fired up in the system. From the first notes of Talking Heads This must be the place I was hooked and was hearing the GB150 sing as it was intended. Its probably overused but, 'a veil was lifted.' The top end shone, the bottom end kicked like a mule and the mids were even more coherent. It's airy with a fantastic 3D space bringing the artists as close to being into the room that I've heard. The difference was quite astonishing. The music is bliss and best of all I'm not listening to the gear anymore
Just to be fair I hooked up Mauro's amp to the SKpre and the benefits were worth the exercise but not quite as substantial. I'll be getting one for the Mauro all the same.
It's been nearly a week with the SKpre's in situ. Whether you want a SKpre to get the most from the GB150 (or 300) I can't say, but a good pre certainly seems a must. This system can take anything I have in my humble collection. If it helps I've listened to Beck, Ben Harper, Cafe del Mar compilations, Buckley, Supertramp, Simply Red, Tchaikovsky, Diana Krall and a bunch of other odds and ends and haven't found any weaknesses at all. It's taken 2 years to get here and well worth the wait... Brilliant!
GB150 - stock values & parts excluding:
Bootstrap (Cerafines)
Feedback (Black Gate std.)
R10, 12 paralleled 47k for bias (30Vac toroid)
C3 silvered mica
Zener mod
SKpre - stock plus 100nF MKT bypass on final PS caps.
Used with Electro Harmonix 6922 & JAN Philips 6922 flavour-additive-enhancer-pre-buffer-thingie.
Marantz CD67MkII (and soon a Monica2 DAC)
Rabbitz' RZ6 SEAS/Peerless 2-way with AR xo. http://www.rzaudio.com/rz52/rz6.htm
The following listening impressions are in 2 parts by necessity.
I've had a GB150 up and running for a few weeks which has been mated to a ESP P88 (1/2 of) connected to a 6922 valve "pre?" It adds some tube flavour, that's all, oh, and a bit of hum. It's had ample running time so here are my impressions.
Previous to the GB150 I was using Mauro Penasa's My_Ref (rev C) from Twisted Pear. The build was stock excluding a Auricap on the input. So Mauro's amp is what the impressions are compared to. I should note that I was extremely impressed by the little Mauro and if I hadn't wanted more drive (headroom) I'd still be using it.
Part 1.
In general the differences are better tonal balance in that it appears more even across the board, more coherent upper end, drive and control. The biggest plus however is all the minute details that were always there but are now more cohesive, the mids in particular. That's not to say these little details detract or demand your attention but more so that you aren't guessing anymore if you heard something. The added depth (imaging) is a big deal too. This is the first amp I've had (though not heard) that projects sound forward of the driver and into the room where locating a performer is as easy as listening. Blacks are black - the amp is quiet. Take the valves out of the equation and I can't hear anything with ear against the drivers.
With regard to negatives, well, there were a couple though by degree's they were slight – note that comment is past tense. The bass seemed lighter than Mauro's amp. Not lean just lighter. At the time I put this down to tighter control or perhaps because the amp has a black gate as the feedback cap, I don't know how much this could affect the sound and if so how long it may need to 'burn-in'. The treble too, seemed a little light-on. This was rationalized easily as the Mauro it quite hot up top and I was about ready to pad down the tweeter a notch or two. Sadly the brain was still getting signals that I was listening to the gear, not just the tunes.
Part 2.
After hours listening to the GB150 I began wondering what the weak link was and it was obviously the op-amp based pre (2134, 843 and even the 627, using a 15VDC regulated PS hooked to a 30VA tranny). You could argue it's the CDP but, your not allowed – besides its being addressed!
After knocking up a pair of SKpre modules and wiring them into the existing pre case they were tested, DC nulled and fired up in the system. From the first notes of Talking Heads This must be the place I was hooked and was hearing the GB150 sing as it was intended. Its probably overused but, 'a veil was lifted.' The top end shone, the bottom end kicked like a mule and the mids were even more coherent. It's airy with a fantastic 3D space bringing the artists as close to being into the room that I've heard. The difference was quite astonishing. The music is bliss and best of all I'm not listening to the gear anymore
Just to be fair I hooked up Mauro's amp to the SKpre and the benefits were worth the exercise but not quite as substantial. I'll be getting one for the Mauro all the same.
It's been nearly a week with the SKpre's in situ. Whether you want a SKpre to get the most from the GB150 (or 300) I can't say, but a good pre certainly seems a must. This system can take anything I have in my humble collection. If it helps I've listened to Beck, Ben Harper, Cafe del Mar compilations, Buckley, Supertramp, Simply Red, Tchaikovsky, Diana Krall and a bunch of other odds and ends and haven't found any weaknesses at all. It's taken 2 years to get here and well worth the wait... Brilliant!
GB150 - stock values & parts excluding:
Bootstrap (Cerafines)
Feedback (Black Gate std.)
R10, 12 paralleled 47k for bias (30Vac toroid)
C3 silvered mica
Zener mod
SKpre - stock plus 100nF MKT bypass on final PS caps.
Used with Electro Harmonix 6922 & JAN Philips 6922 flavour-additive-enhancer-pre-buffer-thingie.
Marantz CD67MkII (and soon a Monica2 DAC)
Rabbitz' RZ6 SEAS/Peerless 2-way with AR xo. http://www.rzaudio.com/rz52/rz6.htm
SKA circuit schematics by Greg Ball. His killer amplifier!
My attachment below shows the simplified version of SKA
as published by Greg, but later removed from public.
It is as far as I know SKA, without paying for it.
This version, I think is not too far from the Real SKA.
Because in another topic in this forum,
he uses this setup in his own simulation pictures attached.
In his attachments (the other topic) we can also see a few resistor values of this circuit.
Which can be of some little value, trying figure SKA out.
The basics of SKA is in this circuit ... for sure
Regards
lineup
fab said:
My attachment below shows the simplified version of SKA
as published by Greg, but later removed from public.
It is as far as I know SKA, without paying for it.
This version, I think is not too far from the Real SKA.
Because in another topic in this forum,
he uses this setup in his own simulation pictures attached.
In his attachments (the other topic) we can also see a few resistor values of this circuit.
Which can be of some little value, trying figure SKA out.
The basics of SKA is in this circuit ... for sure
Regards
lineup
Attachments
AndrewT said:
If you want to know results, you do it, Andrew.
And be sure attach some nice images
My thinking:
Amplifierguru is a good designer. Better than I ever will be.
SKA is a good amplifier topology idea.
But, in my humble opinion,
if want to build diy audio power amp
using MOSFET or any other power FET, JFET
then
I hold master Nelson Pass, still, a little higher up in regards.
From this follows this logical question:
If I can get schematics and instructions and papers and support
here in forum for free by Nelson
with a large number of interesting FET POWER amplifiers to pick from
.. then
why should I pay somebody else
for to get just a fraction of what the real master can give me.
Just asking
Regards
lineup
Amplifier choice VERY much depends on what load you are trying to drive and personal preference of the kind of sound that you like.
amps from greg & nelson are very different animals comparing them is a bit daft especially when you have not heard one of them
I have one of greg's amps - a module pre built by him which I have powered with good quality supply and done the zener mod he suggests plus 2 other minor tweaks. given that you like detail and the load is suitable for a high feedback amp - this amp sounds quite sublime - actually quite amazing
I have a good deal of respect for both these guys
it seems that you do not
and based on the fact that you just posted greg's SKA circuit when he specifically asked for it not be posted - I don't have much respect for you.
amps from greg & nelson are very different animals comparing them is a bit daft especially when you have not heard one of them
I have one of greg's amps - a module pre built by him which I have powered with good quality supply and done the zener mod he suggests plus 2 other minor tweaks. given that you like detail and the load is suitable for a high feedback amp - this amp sounds quite sublime - actually quite amazing
I have a good deal of respect for both these guys
it seems that you do not
and based on the fact that you just posted greg's SKA circuit when he specifically asked for it not be posted - I don't have much respect for you.
Just a heads up this one.
After selling my SKA amps last year so as to go around and explore other possibilities I've now returned back into the fold using GB300 - still probably the best DIY amps available IMO and I've tried nearly all the good ones now. Talk about full circle eh chaps
However I had a bit of tough time tracking Greg down, I half thought he'd gone to ground but after asking about I found he has his own support forum now where other GB users can share ideas, troubleshoot and mods etc.
If anyone else is looking for Greg he can be regularly contacted on the forum:
Here
After selling my SKA amps last year so as to go around and explore other possibilities I've now returned back into the fold using GB300 - still probably the best DIY amps available IMO and I've tried nearly all the good ones now. Talk about full circle eh chaps
However I had a bit of tough time tracking Greg down, I half thought he'd gone to ground but after asking about I found he has his own support forum now where other GB users can share ideas, troubleshoot and mods etc.
If anyone else is looking for Greg he can be regularly contacted on the forum:
Here
lineup said:
From this follows this logical question:
If I can get schematics and instructions and papers and support
here in forum for free by Nelson
with a large number of interesting FET POWER amplifiers to pick from
.. then
why should I pay somebody else
for to get just a fraction of what the real master can give me.
Just asking
Regards
lineup
And in reply to your logical question is an equally logical answer:
You don't have to and clearly your not going to either.
There is only one real master as well and his initials ain't NP. More like ANT.
Just completed an SKPre c/w SKOpticalAttenuator kit
Hi ShinOBIWAN
Yes, the GB300D is a very nice amp, indeed ...
I have just completed an SKPre c/w SKOpticalAttenuator and thought that I would give a short report on it.
This is a very transparent and neutral preamp.
The stage is very open, deep and wide.
It is very musical and detailed.
The highs are very detailed and have no edge to them, as is the mid-range.
The bass is nicely detailed and full, also.
Everything has a very "there" feel to it.
Nothing seems to stand out or be out of place ... very nice
I do have a small humm ... I just need where it coming from and I will be extremely happy, indeed
This preamp is definitely worth a listen
I will give a more detailed evaluation after its had more runin and I have worked out were this humm is coming from.
ciao
Hi ShinOBIWAN
Yes, the GB300D is a very nice amp, indeed ...
I have just completed an SKPre c/w SKOpticalAttenuator and thought that I would give a short report on it.
This is a very transparent and neutral preamp.
The stage is very open, deep and wide.
It is very musical and detailed.
The highs are very detailed and have no edge to them, as is the mid-range.
The bass is nicely detailed and full, also.
Everything has a very "there" feel to it.
Nothing seems to stand out or be out of place ... very nice
I do have a small humm ... I just need where it coming from and I will be extremely happy, indeed
This preamp is definitely worth a listen
I will give a more detailed evaluation after its had more runin and I have worked out were this humm is coming from.
ciao
Hi Stuey
You can also glean details from here
http://ska-audio.com/Forum/YaBB.pl?catselect=general
What are your thoughts on your GB150D?
It sounds like they do not have any of the Mods ...
ciao
You can also glean details from here
http://ska-audio.com/Forum/YaBB.pl?catselect=general
What are your thoughts on your GB150D?
It sounds like they do not have any of the Mods ...
ciao
Hi Stuey
No worries ... in that case, make sure you order the other parts from Greg so that you can do all the mods to your coming 150D's
I have a pair of 300D's which don't need these mods, but like you I have read about all the excellent results from applying the mods to the 150D's
The more I run in the preamp (c/w Optical volume) the better it gets. Very natural, open and dynamic. Very nice, indeed
I have a friend who will be bringing over his Spectron Musician 3 amp, to compare to my 300D. I looking forward to this very much. I will report the results of the comparision
ciao
No worries ... in that case, make sure you order the other parts from Greg so that you can do all the mods to your coming 150D's
I have a pair of 300D's which don't need these mods, but like you I have read about all the excellent results from applying the mods to the 150D's
The more I run in the preamp (c/w Optical volume) the better it gets. Very natural, open and dynamic. Very nice, indeed
I have a friend who will be bringing over his Spectron Musician 3 amp, to compare to my 300D. I looking forward to this very much. I will report the results of the comparision
ciao
I've just completed a SKA build, in the testing phase at the moment but it is really quite amazing.
I've built a preamp using 2 SKPre modules and the LDR volume with external power and 2 x GB150S. My source is a highly modded Arcam Alpha 5+(NOS, caps etc) and it's going into 2 very old JPW Sonata speakers (bookshelf and budget at the time but I like them).
The clarity of this set up is unbelievable, the amps simply do not hinder or colour the music in any way. The dynamic range and clarity opened up a recording of Nimrod (Elgar - Enigma variations) to the extent it bought me to tears. The emotion and feeling of the orchestra's performance is delivered to you in a form that can only be better by physically playing yourself.
I have played a range of discs from opera, 80's alternative to industrial metal and it is the purity of the music that stands out on every disc. The one down side is I have discovered a couple of CD's where the poor quality of the recording is revealed and the disc becomings unlistenable as the amps deliver the things you don't want to hear! I see this as a good thing, poor recordings have no place here. I do not want colour, bloom, warmth etc with my music, I want the music itself and this is what the SKA delivers.
I'm looking forward to listening more and more.
As a side note, Greg is a very helpful chap and his tech support has been second to none through this build.
Cheers
Iain
I've built a preamp using 2 SKPre modules and the LDR volume with external power and 2 x GB150S. My source is a highly modded Arcam Alpha 5+(NOS, caps etc) and it's going into 2 very old JPW Sonata speakers (bookshelf and budget at the time but I like them).
The clarity of this set up is unbelievable, the amps simply do not hinder or colour the music in any way. The dynamic range and clarity opened up a recording of Nimrod (Elgar - Enigma variations) to the extent it bought me to tears. The emotion and feeling of the orchestra's performance is delivered to you in a form that can only be better by physically playing yourself.
I have played a range of discs from opera, 80's alternative to industrial metal and it is the purity of the music that stands out on every disc. The one down side is I have discovered a couple of CD's where the poor quality of the recording is revealed and the disc becomings unlistenable as the amps deliver the things you don't want to hear! I see this as a good thing, poor recordings have no place here. I do not want colour, bloom, warmth etc with my music, I want the music itself and this is what the SKA delivers.
I'm looking forward to listening more and more.
As a side note, Greg is a very helpful chap and his tech support has been second to none through this build.
Cheers
Iain
Excellent, guys. I'm excited! Unfortunately I still don't have the kits - Australia Post seems to have had a glitch in its systems. I'm counting on arrival on Monday...
Iihay, what was the transformer spec you used? And did you simply use a single transformer, or a dual mono setup?
Thanks.
Stuey
Iihay, what was the transformer spec you used? And did you simply use a single transformer, or a dual mono setup?
Thanks.
Stuey
You shoudl be excited, it's great I used a single toroid 30 0 30 toroid, if you want to see the layout I have a post over at Greg's forums showing my build.
The post is variable I just got a BassXt from Greg all the way to the UK in just a few days but the last lot took weeks.
Transformer spec:
VA Rating 300VA
Input Voltage 230V(ac)
Output Voltage 2 x 0 - 30V(ac)
Output Current 5A
Regulation (Typ.) 8%
Dimensions (L x W x H) 58 (H) x 115 (Dia) mm
Temperature Rise 60°C
Weight 2.3kg
Have fun.
Iain
I used a single toroid 30 0 30 toroid, if you want to see the layout I have a post over at Greg's forums showing my build.The post is variable I just got a BassXt from Greg all the way to the UK in just a few days but the last lot took weeks.
Transformer spec:
VA Rating 300VA
Input Voltage 230V(ac)
Output Voltage 2 x 0 - 30V(ac)
Output Current 5A
Regulation (Typ.) 8%
Dimensions (L x W x H) 58 (H) x 115 (Dia) mm
Temperature Rise 60°C
Weight 2.3kg
Have fun.
Iain
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.