Shin:
I built a 4 ch chipamp for someone that bought the Brian kit, IIRC.
I applied my own minor design changes which are more in tune
with common sense engineering than audio voodoo. I think I
have schematics somewhere I can show you. Point is, don't think
too hard about the chipamp project, these are simple projects,
lipstick on a pig, ie .. no matter what you do, the power limitation
is the biggest handicap.
I don't think you will be satisfied with low power on your loudspeaker. You may be satisfied in the beginning but as
time passes you will desire more headroom. Those ATC drivers
can handle much more and they should be pushed closer to
their abilities.
I built a 4 ch chipamp for someone that bought the Brian kit, IIRC.
I applied my own minor design changes which are more in tune
with common sense engineering than audio voodoo. I think I
have schematics somewhere I can show you. Point is, don't think
too hard about the chipamp project, these are simple projects,
lipstick on a pig, ie .. no matter what you do, the power limitation
is the biggest handicap.
I don't think you will be satisfied with low power on your loudspeaker. You may be satisfied in the beginning but as
time passes you will desire more headroom. Those ATC drivers
can handle much more and they should be pushed closer to
their abilities.
thylantyr said:
I agree but its already gathered momentum now. These are cheap cheap projects and the cases are designed with reusability in mind so I can swap out the modules and PSU's should I decide to.
I also think your right about the power output of these things, its low by anyone's account. The ATC's will soak up much more power and the mid alone really demands 200w to be heard at the top of its SPL range and with full authority.
I mentioned it in another thread on here but I'm really waiting on Gregs new design. The GC's are a stop gap and just to follow up on the impressive initial showing in my mates 2ch setup. I'm not expecting miracles from such basic designs but what I've heard so far is very good. Shame they have a low output.
I've also bought some LM4780's which I can use in parallel to boost the power to around 100w still weak for the ATC's but better.
I've been in touch with Nuuk too and plan to order some of those Skynet SMPS's should things initially go well.
A couple of things, firstly Alu has grain which you must sand with to get a decent finish. And use lots of lubricant (soapy water). Depending on what the scratches are like you can start at around 320 grit and work up to 600 or so and you should get an ok finish. Of course hand sand with full strokes up the whole length of the piece. Belt sand works here too, but your palm sander is probably no good. But tbh, it was more bother than it was worth when you consider it cost me £10 per chassis to have them anodized.ShinOBIWAN said:
Again, Peter has mentioned another chemical finish method which is not a robust a finish as anodizing but looks excellent on the DAC enclosure he built for me. A search might find you some more info on his method.
If you look at amplification from purely a "watts" scenario - you are bound to be mislead. In otherwords a little "voodoo" is in order here.
Just from a "gain" perspective your lowest eff. driver (the midbass) at 85db, (assuming that includes baffle step loss), will have at least 15db of headroom in a typical GC (..depending on the PS). 100 db isn't just loud - it can be painfull. (..and of course how loud it sounds is also a function of room effects and ambiant noise.)
Where the "voodoo" steps in is with regard to an amplifier's current handling and the driver's mms. (..the higher the mms, the more current needed.) Its in this instance where the amplifier may not be "enough" for a given driver.
Effectivly this means that neither the tweeter nor the midrange should need any more watts given their eff. and their mms. In fact this is the area where Peter's "tweaking" the power supply will pay dividends, and can allow subtle yet distinct alteration of the sound.
On the other hand the midbass may be suffering due to insufficient current. Subjectivly this tends to decrease dynamics, punch, drive, clarity, and transparency to some extent. This is most noticible with bass reflex designs where the amp with the higher current capablity seems to provide another half-octave of extension in addition to the above subjective comments.
Its also possible with some orchestral works that have very large dynamic ranges that those dynamic peaks will be in "peril" due to insufficient watts for the midbass.
Just from a "gain" perspective your lowest eff. driver (the midbass) at 85db, (assuming that includes baffle step loss), will have at least 15db of headroom in a typical GC (..depending on the PS). 100 db isn't just loud - it can be painfull. (..and of course how loud it sounds is also a function of room effects and ambiant noise.)
Where the "voodoo" steps in is with regard to an amplifier's current handling and the driver's mms. (..the higher the mms, the more current needed.) Its in this instance where the amplifier may not be "enough" for a given driver.
Effectivly this means that neither the tweeter nor the midrange should need any more watts given their eff. and their mms. In fact this is the area where Peter's "tweaking" the power supply will pay dividends, and can allow subtle yet distinct alteration of the sound.
On the other hand the midbass may be suffering due to insufficient current. Subjectivly this tends to decrease dynamics, punch, drive, clarity, and transparency to some extent. This is most noticible with bass reflex designs where the amp with the higher current capablity seems to provide another half-octave of extension in addition to the above subjective comments.
Its also possible with some orchestral works that have very large dynamic ranges that those dynamic peaks will be in "peril" due to insufficient watts for the midbass.
As always Scott your considered and level headed approach is refreshing.
I like Thy's approach to amplfiers, its simple, brutal and honest. You can never claim he's underpowering his speakers when he's using 15kw top of the line Crest amps in conjunction with a host of other high power PA amps.
There's also the other end of the spectrum whereby some get by on just a few watts in the form of SET's. The gainclones offer a little more headroom than these but not massively so.
I'll only be using gainclones on the mid and treble. Obviously an LM3875 is more than enough for the R2904 treble. But the mid is of concern, ATC drivers can soak up large amounts of power - at least twice their continuous rating of 150w and also love big current. I was chatting with an SCM50SL user who has Krell FPB700 monoblocks and feels that in comparison to his previous amp that they have only just began to open up fully on the end of these monsters.
The ATC mid is deceptive because of its 94dB sensitivity rating, you'd think it was efficient from that but experience tells me that it will take whatever it can get. I've had 50w, 150w, 200 and 300w amps all driving these ATC mids and each time they just ate up whatever was thrown at them. As you've said Scott, its a matter of current delivery as big amps do that well.
ATC themselves use 50, 100 and 200w for HF, mid and bass respectively in their active version of the SCM50. I'm essentially using the same drivers bar the treble.
I don't listen loud, I'd estimate on average its 70-80dB and sometime go to maybe 100dB if the mood takes me. Are the GC's going to be enough to get by on and still get something like the sound that I heard in my mates 2ch setup on the end of the Wilson Benesch Discoveries?
I like Thy's approach to amplfiers, its simple, brutal and honest. You can never claim he's underpowering his speakers when he's using 15kw top of the line Crest amps in conjunction with a host of other high power PA amps.
There's also the other end of the spectrum whereby some get by on just a few watts in the form of SET's. The gainclones offer a little more headroom than these but not massively so.
I'll only be using gainclones on the mid and treble. Obviously an LM3875 is more than enough for the R2904 treble. But the mid is of concern, ATC drivers can soak up large amounts of power - at least twice their continuous rating of 150w and also love big current. I was chatting with an SCM50SL user who has Krell FPB700 monoblocks and feels that in comparison to his previous amp that they have only just began to open up fully on the end of these monsters.
The ATC mid is deceptive because of its 94dB sensitivity rating, you'd think it was efficient from that but experience tells me that it will take whatever it can get. I've had 50w, 150w, 200 and 300w amps all driving these ATC mids and each time they just ate up whatever was thrown at them. As you've said Scott, its a matter of current delivery as big amps do that well.
ATC themselves use 50, 100 and 200w for HF, mid and bass respectively in their active version of the SCM50. I'm essentially using the same drivers bar the treble.
I don't listen loud, I'd estimate on average its 70-80dB and sometime go to maybe 100dB if the mood takes me. Are the GC's going to be enough to get by on and still get something like the sound that I heard in my mates 2ch setup on the end of the Wilson Benesch Discoveries?
My father had an old pair of nelson reeds for many years that had the ATC domes powered by an old Threshold beast "I forgot the model number" ...but they took every watt with ease and wanted more...still to this day one of the most dynamic non horn laodspeaker I have ever heard...
trusound said:
Yep those ATC mids do have some amazing dynamics and general snap that can make you flinch with the right volume and track.
My only real critisicm is that dynamics can seem somewhat hyped when listening at low SPL's, with more higher SPL's this seems to re-align with what you'd expect. Its as if the quiet sections are in music are too quite and the loud sections are too full on when listening at quiet levels. Its an unusual sound but this sorts itself out at higher SPL's.
ShinOBIWAN said:
Almost certainly if you are just using them for mid and treble. I even think you could use them with the midbass with great success (..provided you have substantial reservoir capacitance in the PS).
Note however that they could well sound different, particularly because you have an active loudspeaker.
re: monster amps.
I don't want the amplifier to contribute to SQ anomolies. I want
the main SQ to come from the speakers and environment
and EQ/crossover as needed.
Monster amps have the ability to play at low volume too,
people forget 😀
I do alot of low level listening but there is potential for more
without worries about exceeding the amplifier's performance
envelope. In other words, the idea is when I crank the music
I never say that my power plant is running out of fuel unless
I trip a home circuit breaker
This gives me the ability to focus on a better speaker
design if the one I have is struggling. If I remove the amplifier
as the variable, I simplify the quest.
From what I can see, your Perceive project is done if
you don't venture into voodoo land.
You have a good source, good crossover, and just get
some monster amps to give that you anomoly free SQ
and let your speakers do all the work.
You should be bridging the big amps for uber headroom.
Who wants squashed dynamics when listening to drum solos,
etc. 🙂
... then plan your next speaker project as you will eventually
get bored with these, it's the evil way unless you can
control the evil audio demons
I don't want the amplifier to contribute to SQ anomolies. I want
the main SQ to come from the speakers and environment
and EQ/crossover as needed.
Monster amps have the ability to play at low volume too,
people forget 😀
I do alot of low level listening but there is potential for more
without worries about exceeding the amplifier's performance
envelope. In other words, the idea is when I crank the music
I never say that my power plant is running out of fuel unless
I trip a home circuit breaker
This gives me the ability to focus on a better speaker
design if the one I have is struggling. If I remove the amplifier
as the variable, I simplify the quest.
From what I can see, your Perceive project is done if
you don't venture into voodoo land.
You have a good source, good crossover, and just get
some monster amps to give that you anomoly free SQ
and let your speakers do all the work.
You should be bridging the big amps for uber headroom.
Who wants squashed dynamics when listening to drum solos,
etc. 🙂
... then plan your next speaker project as you will eventually
get bored with these, it's the evil way unless you can
control the evil audio demons
I know what your saying Thy.
The GC's aren't my main choice, if I could afford it I'd have another two 1200E's but I'm too poor to do that at the minute. I don't think that messing around with modding amplifiers is voodoo, although the gains are pretty insignificant compared to the progression offered by things such as new loudspeakers, DRC and room treatments. Its all valid and whatever keeps your mind busy is a good thing in my book. The worst that comes from virtually any amp tinkering is that it could have been a waste of money. Since were talking gainclones here rather than swapping out the bottles of a 300B, its all rather budget anyhow and since there's plenty of GC fanatics the stuff is easy to sell on should you decide its not doing it for you.
All this talk is somewhat premature because I haven't even heard the gainclones on the end of the speaker yet and 'what if's' won't get me any closer to the truth. I know the 1200E will handle that ATC midbass very easily. And foresight gave me the sense to buy an LM4780 from Peter so I'll config that for parallel and give it a go with the mid if I think the LM3875 is lacking.
On another note I've ordered four of the SMPS modules from Nuuk to try out with the GC's. Perhaps even more alarming is that they have 12v rails! So this means that power output will be around 20w. I've also got some 25-0-25 toroids to try out alongside Peter's Blackgate PS. So I've clearly got plenty to mess around with. I've had confimation that my Blackgates have been shipped and hopefully I'll have these tommorow so that will be when I can start playing.
Looking at the common sense side of things, the ATC will be putting out 94dB with a single watt from 1m distance. Since my listening position is only 2.5m from the speakers then its easy to see why I don't need huge power, but as you've said, its nice.
The GC's aren't my main choice, if I could afford it I'd have another two 1200E's but I'm too poor to do that at the minute. I don't think that messing around with modding amplifiers is voodoo, although the gains are pretty insignificant compared to the progression offered by things such as new loudspeakers, DRC and room treatments. Its all valid and whatever keeps your mind busy is a good thing in my book. The worst that comes from virtually any amp tinkering is that it could have been a waste of money. Since were talking gainclones here rather than swapping out the bottles of a 300B, its all rather budget anyhow and since there's plenty of GC fanatics the stuff is easy to sell on should you decide its not doing it for you.
All this talk is somewhat premature because I haven't even heard the gainclones on the end of the speaker yet and 'what if's' won't get me any closer to the truth. I know the 1200E will handle that ATC midbass very easily. And foresight gave me the sense to buy an LM4780 from Peter so I'll config that for parallel and give it a go with the mid if I think the LM3875 is lacking.
On another note I've ordered four of the SMPS modules from Nuuk to try out with the GC's. Perhaps even more alarming is that they have 12v rails! So this means that power output will be around 20w. I've also got some 25-0-25 toroids to try out alongside Peter's Blackgate PS. So I've clearly got plenty to mess around with. I've had confimation that my Blackgates have been shipped and hopefully I'll have these tommorow so that will be when I can start playing.
Looking at the common sense side of things, the ATC will be putting out 94dB with a single watt from 1m distance. Since my listening position is only 2.5m from the speakers then its easy to see why I don't need huge power, but as you've said, its nice.
The 4 channel GC I assembled for a friend was LM4780
based. It's good for what it is, but this forum has hyped up
the chipamp way beyond belief. Chimpamps
have been used in audio for decades, people act like it's
something new
Re: no money
Many people suffer from this strange phenomena,
would you beleive if I told you my crazy audio project
quest began near year 2000? Maybe even 1999.
I found the drivers of choice in year 2002. 4 years later,
I'm still collecting parts.
Be patient if you need to be as long as you get
what you want.
If I had a bucket of cash, I'd be done long ago. Point
is ....... the show much go on for us audio freaks.
The Frodo quest looks easy by comparison
based. It's good for what it is, but this forum has hyped up
the chipamp way beyond belief. Chimpamps
have been used in audio for decades, people act like it's
something new
Re: no money
Many people suffer from this strange phenomena,
would you beleive if I told you my crazy audio project
quest began near year 2000? Maybe even 1999.
I found the drivers of choice in year 2002. 4 years later,
I'm still collecting parts.
Be patient if you need to be as long as you get
what you want.
If I had a bucket of cash, I'd be done long ago. Point
is ....... the show much go on for us audio freaks.
The Frodo quest looks easy by comparison
Have been listening to a pair of the GC's this evening, not with the Perceives but on the end of the ATC SCM7's.
First impressions aren't good. They sound flat, boring and claustrophobic, the sound is as small as the amps themselves. These just don't sound anything like convincing, play an acoustic piece and it just sounds synthesised and unrelated. These aren't a patch on the SKA's I had previously nor do they sound anything like what I heard with the Discoveries.
I'll give them a bit more time to break-in but the first impression is usually the lasting one. I'll also see how they fare with the Audax MTM's which should be a much easier load than the SCM7's.
First impressions aren't good. They sound flat, boring and claustrophobic, the sound is as small as the amps themselves. These just don't sound anything like convincing, play an acoustic piece and it just sounds synthesised and unrelated. These aren't a patch on the SKA's I had previously nor do they sound anything like what I heard with the Discoveries.
I'll give them a bit more time to break-in but the first impression is usually the lasting one. I'll also see how they fare with the Audax MTM's which should be a much easier load than the SCM7's.
ShinOBIWAN said:
I've seen other responses like this as well. It appears to be something of a "coin-flip" with respect to sound quality/user response. I've personally heard the GainCard and I can say it sounded pretty good with the with the Thiel 2.somethings I listend to (..though they did have a pretty flat 4 ohm impedance).
I definitly agree with the first impression (at least with most electronics). Only once have a heard a solid state amp where there was a dramatic change in sound quality with about 100 hours play-time.. a Cello Ltd. 50 watt amp (by Mark Levinson the man). Grainy and flat is what what it sounded like fresh out of the box - 100+ hours latter it was smooth with rounded imaging and quite dimensional (..still wasn't worth anywhere near the 5k over ten years ago that they were asking). I hope though that your experience is the exception (..i.e. more like the Cello amp).
ShinOBIWAN said:
If frequency response is good, distortion and noise low,
as is any good amplifier design, the user will perceive {pun}
power as the biggest variable of sound quality of an amplifier.
Your response supports this. Save up and get some PLX amps
😱 😀 😎
I assume you're using the BG caps. Trust me, it'll change. Maybe not significantly better, but just maybe. My first LM3875 amp with caddocks and BG caps is the worst sounding I made. The chip amp experience did get much better with perseverance.
Thy, I like your attitude - Watt Junkie! 😀
Thy, I like your attitude - Watt Junkie! 😀
Shin,
What happened with Aksa's you had? You got rid of them? I've heard that it is exceptional amp. AFAIK, GC isn't near it's performance
What happened with Aksa's you had? You got rid of them? I've heard that it is exceptional amp. AFAIK, GC isn't near it's performance
Tomac said:
I sold the AKSA 55N+ some time ago. The GC's have the capacity to sound good but I'm just not feeling that on the end of the tough to drive ATC's.
Vikash maybe right about the BG's, I'm using 1000uf STD types on the supply and 100uf N types at coupling position. I'll give them a little more time before sending them to the classifieds 😉 😀
David Gatti said:Give in to the dark side & go passive - you know you want to
"I'll never join you!" 😀
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