Re: GC and ATC
Nice friend you have there! 🙂
I've know someone with the SCM50SL's hooked upto Krell FPB700CX monoblocks, those amps cost as much as the speakers. And he informed me that they only now do they really sound at their best.
Its probably to be expected that a 50w @ 1%THD amp won't have a chance in hell of doing them justice. I'd hate to see some 10w SET trying to get them going.
Bratislav said:
Nice friend you have there! 🙂
I've know someone with the SCM50SL's hooked upto Krell FPB700CX monoblocks, those amps cost as much as the speakers. And he informed me that they only now do they really sound at their best.
Its probably to be expected that a 50w @ 1%THD amp won't have a chance in hell of doing them justice. I'd hate to see some 10w SET trying to get them going.
The QSC SRA series looks pretty nice too
SRA discontinued.
SRA = fanless
When you look at the guts of these products,
they are more alike than different. From an audio signal
path point of view {not counting crossovers},
PLX = PLX2 = PL2 = SRA
Download the schematics and see for yourself not
😎
SRA discontinued.
SRA = fanless
When you look at the guts of these products,
they are more alike than different. From an audio signal
path point of view {not counting crossovers},
PLX = PLX2 = PL2 = SRA
Download the schematics and see for yourself not
😎
thylantyr said:
The SRA is about the only fanless pro amps that I know of. I really need fanless TBH.
Any others you could suggest?
trusound said:
Yes.
I started audio in 1983 with my car. In 1986 it had six monoblock amps and two stereo amps fully active, many drivers, 4 way
design.
Stuff we did then was never done in home audio.
Stuff we did then is rarely seen in commercial home audio today.
Stuff we did then is showing up more and more in DIY home
audio.
Time to move on and exit the dark ages
jleaman said:
I have;
planar tweeters with awesome SQ and SPL potential.
103db sensitivity, 13 ohm.
I have 100dB sensitivity rated midranges, 8 ohm.
I can drive those speakers very well with low power
but I'm still going to connect those drivers to my bridged
proamps because the drivers are not being pushed to
their performance envelope on musical transients with
low powered amps.
On a transient, the low powered amp reaches it's limit first
before the speaker does.
With a high powered bridged proamp, the amplifier becomes
the lesser variable and all I do now is worry about driver limits.
I can over drive a high quality Focal dome into distortion due
to driver limitations, but it takes a lot to overdrive better drivers.
In Shins case, the dome will be the weakest link, the ATC
mid and woofer can probably handle a few kilowatts of peak
power easy.
ShinOBIWAN said:
SRA was their studio amp, not the touring amp
Many proamps have variable speed fans and fan rotation
speeds up as temp rises. Easy load, the fan spins slow,
less wind noise. etc.
Many folks on AVS are using the entry level Crown XLS
amps for HT, but those amps have no variable speed,
plus there is two fans that are noisy. They do mods.
Either they swap out the fans with low noise fans or
they install an inline resistor to reduce voltage to reduce
fan speed to reduce noise, but they sacrifice cooling.
Most of those HT systems are 8 ohm 'easy speakers' so
they get away with it. Some folks place their amp rack in a closet to muffle the noise.
In my case, I was going to make an enclosed amp rack to
minimize noise, but have two vents. Suck air from the bottom, exhaust air out the top since my room is small.
Any DJ rental stores to try QSC, Crown, etc amps for a day ?
fyi;
QSC RMX vs. PLX internal pics.
http://home.pacbell.net/lordpk/qsc/
What I like about the QSC design {others may do it too} is
the transistors are not insulated from the heatsink using
mica or whatever insulators, the transistor is mounted directly
on the aluminum heatsink. RMX uses a grounded collector
topology to accomplish this. PLX uses a more common topology
but they isolate the heatsinks from ground using insulators.
See pics. PLX has more heatsink, heatsink shroud for better
wind tunnel cooling. SMPS too! ... very nice design considering
it's a decade old design. All the proaudio folks love this amp
to run the mids and tweeters. For woofers, it's a mixed bag
as some folks need more power than what a single PLX offers.
Re: Re: GC and ATC
I know ! 😎
The only problem was getting them home. At 80kg each even two people struggled to get them in/out of the back of my 4WD.
Actually, valve amps (OK, maybe not 10W) will sound better with ATCs as they will clip gracefully and simply compress (which is far less intrusive than rubbish generating SPIKE protection of chip amps). 50W of good amplification will in fact be plenty for 'super' 75-150 (as you already said it is plenty efficient at 94dB and quite benign at 16 ohms) - the problem is occassional peak which triggers SPIKE and that, as you know, sounds crap. Unfortunately SPIKE is not defeatable, and it is quite 'intelligent' in its operation, so it is not easy to predict when it will chop the signal (so you can't even have say LED to warn you to back off). It varies with chip temperature, signal voltage, current, phase, which constellation Mars resides in and god know what else.
Shame, 'cause when those chips are in their operating region they actually sound very nice indeed.
Bratislav
ShinOBIWAN said:
I know ! 😎
The only problem was getting them home. At 80kg each even two people struggled to get them in/out of the back of my 4WD.
Actually, valve amps (OK, maybe not 10W) will sound better with ATCs as they will clip gracefully and simply compress (which is far less intrusive than rubbish generating SPIKE protection of chip amps). 50W of good amplification will in fact be plenty for 'super' 75-150 (as you already said it is plenty efficient at 94dB and quite benign at 16 ohms) - the problem is occassional peak which triggers SPIKE and that, as you know, sounds crap. Unfortunately SPIKE is not defeatable, and it is quite 'intelligent' in its operation, so it is not easy to predict when it will chop the signal (so you can't even have say LED to warn you to back off). It varies with chip temperature, signal voltage, current, phase, which constellation Mars resides in and god know what else.
Shame, 'cause when those chips are in their operating region they actually sound very nice indeed.
Bratislav
Vikash very kindly lent me his proto LM3886 with a decent PSU and snubber:
I've been checking it since yesterday evening, I've noticed an immediate improvement over my own LM3785 implementation and I'm pretty impressed so far with just a couple of reservations.
Will post more later, I'm going to back to listening 🙂
An externally hosted image should be here but it was not working when we last tested it.
I've been checking it since yesterday evening, I've noticed an immediate improvement over my own LM3785 implementation and I'm pretty impressed so far with just a couple of reservations.
Will post more later, I'm going to back to listening 🙂
Spent a fair amount of time with Vik's LM3886 now and have used them for all sorts: watching a movie(Running Scared), a few hours of TV, couple of hours gaming and several hours of music. So plenty of critical and non critical listening from a variety of sources.
I'm finding that the GC's have an appeal all of their own. The treble seperation is particularly good making 'spaces' seem more real. The mids are straight down the line too with no emphasis on any particular frequency making sounds seem equal and even handed with all frequencies being equally as important and audible. Its pretty sweet overall. I think the Vik's LM3886 makes a great HT amp with its clean nature and I never felt like I was really straining to hear anything in the mix.
My only complaints are that they still can't do much with the ATC SCM7's - my comments above are with reference to some Mission 771e and also a cheapo Audax based MTM. With the ATC's they sound as though everything good about them has been robbed and instead a flat, lifeless and boring fascimille of the music has replaced it. The ATC SCM7's certainly sound better, whilst not on the end of the GC's, than either of the two examples above but in this case I actually prefer not to listen SCM7's.
I can't really judge the bass as those Missions and Audax's hardly extend below 60hz what with them being tiny bookshelf designs. What little bit I heard sounded tuneful though, if a little flabby but I hear that everytime with these speakers and its just part of their sound ie. cheap commercial speakers have naff bass.
On another note, the amps seem to run much hotter than my LM3785's. Way hotter in fact, I've got them fastened down to a slab of alu using a blob of thermal compound and some pegs to hold them. After a loudish listening session I felt the sink and could barely hold my fingers on it for more than a few seconds, I did of course immediate turn the amps of and allowed them to cool but I'm going to add more heatsink area just to keep them and the speakers safe.
Next up is the LM3785 with SMPS vs. Viks LM3886 🙂
I'm finding that the GC's have an appeal all of their own. The treble seperation is particularly good making 'spaces' seem more real. The mids are straight down the line too with no emphasis on any particular frequency making sounds seem equal and even handed with all frequencies being equally as important and audible. Its pretty sweet overall. I think the Vik's LM3886 makes a great HT amp with its clean nature and I never felt like I was really straining to hear anything in the mix.
My only complaints are that they still can't do much with the ATC SCM7's - my comments above are with reference to some Mission 771e and also a cheapo Audax based MTM. With the ATC's they sound as though everything good about them has been robbed and instead a flat, lifeless and boring fascimille of the music has replaced it. The ATC SCM7's certainly sound better, whilst not on the end of the GC's, than either of the two examples above but in this case I actually prefer not to listen SCM7's.
I can't really judge the bass as those Missions and Audax's hardly extend below 60hz what with them being tiny bookshelf designs. What little bit I heard sounded tuneful though, if a little flabby but I hear that everytime with these speakers and its just part of their sound ie. cheap commercial speakers have naff bass.
On another note, the amps seem to run much hotter than my LM3785's. Way hotter in fact, I've got them fastened down to a slab of alu using a blob of thermal compound and some pegs to hold them. After a loudish listening session I felt the sink and could barely hold my fingers on it for more than a few seconds, I did of course immediate turn the amps of and allowed them to cool but I'm going to add more heatsink area just to keep them and the speakers safe.
Next up is the LM3785 with SMPS vs. Viks LM3886 🙂
Interesting findings. I think 25v secondaries could be contributing to the excessive heat. I also used a large cap value on the chip pins (2200uf) which should ideally be much much smaller (allegedly) with this kind of PSU (unfortnately un-testable in the current p2p setup). This may or may not improve the sound (although I don't see it changing your impression with the ATC's).
I believe the amp implementation and not the PSU is responsible for the better mid/hi sound seperation and would think it unlikely that any psu change would make the lm3875 kit you have sound favourable over the lm3886 you're testing. The hi-cap psu gives it a better low end without affecting the mid/hi's. Again allegedly.
By all means try that as well if you like -> The PSU into the LM3875.
On a final note, I've only tested the setup for minutes as opposed to hours like you - so you're actually burning it in for me 😀 I'm just glad it hasn't blown any of your stuff 😉
I believe the amp implementation and not the PSU is responsible for the better mid/hi sound seperation and would think it unlikely that any psu change would make the lm3875 kit you have sound favourable over the lm3886 you're testing. The hi-cap psu gives it a better low end without affecting the mid/hi's. Again allegedly.
By all means try that as well if you like -> The PSU into the LM3875.
On a final note, I've only tested the setup for minutes as opposed to hours like you - so you're actually burning it in for me 😀 I'm just glad it hasn't blown any of your stuff 😉
m0tion said:
More pics? I thought I'd bored everyone to death with these already.
Here's a few more for those still awake 😀
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An externally hosted image should be here but it was not working when we last tested it.
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And here's a couple of the mid/treble hookup cable.
Completely thankless task building those:
Cable is Qed Genesis Bi-wire with Neutrik Ag Silver plated speakon and Black Rhodium locking banana's.
Completely thankless task building those:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Cable is Qed Genesis Bi-wire with Neutrik Ag Silver plated speakon and Black Rhodium locking banana's.
Member
Joined 2002
Its biwire though so that's why its fairly hefty.
TBH I wish I'd gone with something a little more flexible as this stuff doesn't do corners.
TBH I wish I'd gone with something a little more flexible as this stuff doesn't do corners.
I know the feeling, had QED Silver Anniversary Biwire on my main speakers downstairs, got sick of the snakes so replaced with some arctic grade mains cable from CPC - less then 1/10 price, but still looks cool (nice blue) and is loads more flexible.
richie00boy said:
I'm not sure why I spent so much on the cabling, I'm the kinda guy that pokes fun at expensive cables since I've never noticed any difference between OFC solid core and some Nordost Blue Heaven I wasted good money on a few years ago.
I didn't pay the recommended £60 per meter for the Qed Genesis biwire though and instead bought from an ebay seller for a more sensible £25p/m. Still rip off but I figured I'd already made a considerable investment in the speakers so why not have fancy looking cable to go with it. I still fully believe that the £3p/m stuff I tested, evaluated and measured the speakers with sounds equally good. Thankfully I only need short runs of 2m so in the end it worked out around £240 for all the cabling including internal wiring on the speakers plus all the connectors which I again picked up cheap on ebay.
I'm glad to see that even given your obvious analytical skills when auditioning your amps, that you have not fallen into the cable trap, or been swayed by hype and looks. I fully understand your point in wanting to have fancy cable to keep up with such superb speakers from a cosmetic/subconscious view at least.
What you need now is a review of your product compared
to store bought speakers you auditioned. What the readers
might be interested in knowing is how much money do you
have to spend to get that sound if not DIY. I know the answers,
but it's good to do a final evaluation vs. store bought.
If would be cool if you can audition high end speakers
for comparison. There are snobophiles out there that
never see any value in DIY and nobody can meet or
beat store bought from famous vendors. 🙄
Your project would make a good candidate for display,
make a dedicated website for DIY'er ammunition, I can
use it on the snob forums. /rofl/
😎
to store bought speakers you auditioned. What the readers
might be interested in knowing is how much money do you
have to spend to get that sound if not DIY. I know the answers,
but it's good to do a final evaluation vs. store bought.
If would be cool if you can audition high end speakers
for comparison. There are snobophiles out there that
never see any value in DIY and nobody can meet or
beat store bought from famous vendors. 🙄
Your project would make a good candidate for display,
make a dedicated website for DIY'er ammunition, I can
use it on the snob forums. /rofl/
😎
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