| Peter Daniel |
It is well known that the GainCard amp started a new trend in diy circles and many tried to copy the design, if not the chassis construction then at least the circuitry. My first amp was also very much influenced by the Card and I thought initially that this is as far as one could go with the design.
However, after experimenting with different chassis built and more esoteric construction methods, it seems like the original concept can be further improved. After the controversy thread on AA, I was also bugged by Yoshi Segoshi of Sakura Systems to come up with something more original than merely a copy of the 47Labs amp and to create a Patek of GC amps, while Gaincard would still be a Rolex.;)
So here's my attempt at Patek amp. It uses similar size as Card, but it's slightly higher. I know it doesn't look very sexy, but the main concern was to achieve the mastery in the sound and not in the looks. |
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| Peter Daniel |
I always listen to a good advice and also this time a quote from Thorsten gave some ideas for a new approach:
| quote: | Originally posted by Kuei Yang Wang
Well, I HATE (not) to say it, but you may wish to read my original comments on CFrasers Gainclone "Builder Data" Page... Look for "Thorstens Thoughts"....
http://home.ca.inter.net/~cfraser/Gainbuilder.htm
:devilr:
What I would suggest as Heatsink in such a design is actually a block of Bronze with several chimeys drilled out.
Keep the wood and C37 Lacquer it. And probably some Altman "Tubolator" Lacquer on the Chip and C37 on all Capacitors, plus wooden, C37 lacquered Capacitor Clamps for the (plastic stripped) PSU Cap's. Oh yes, also avoid any magnetic screws....
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So I decided on the best materials I could use in such design and the core of the amp, the main support bar, is made out of bronze, while the front and back is out of 1/4" copper flat bars and "I keep the wood" so the sides are made of maple.
The size is about 5" x 6" and it's 2.5" high (excluding spikes) |
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| Cradle22 |
EDIT: I was too fast, insights are coming in...!
Hi!
But in what ways does it differ exactly from the original GC concept, or the "improved inverted GC concept" developed by you and members of this forum?
Don't just show off you chassis building capabilities ;) , offer some insights!
Circuitry? Chip (do I dare to ask? I assume that the LM3875 is still being used on this one)? :confused:
Shed some light!
Bye,
Arndt |
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| Peter Daniel |
| Here's the better detail of the main bar. I used a similar method to attach the chip as in my monoblocks as this seems to work very well. The parts include Caddock for feedback and some Vishays for input and ground connection. |
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| Peter Daniel |
| I chose to use the best parts here and this amp features BG N caps. The wooden sides create the capacitor clamps. They are shielded with mu-metal strips. |
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| Peter Daniel |
| I didn't drill the convection channels through bronze slab, as from my experience the GC doesn't normally run that hot and I preferred to use top and bottom covers for a complete look. Here I used a perforated, ultralight aluminum panels. They shouldn't affect the sound in any way, as I know from other members, that this may be problematic. Their surface also helps to dissipate more heat and the holes keep the inside cooler. As usually, i'm using those brass spikes, as I get them pretty cheap and they sound good. One spike in a back, right in a place where the chips are mounted. |
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| Peter Daniel |
The rear panel is pretty straightforward and the only upgrade from my usual stuff are Kimber RCA jacks. I didn't implement volume control in this amp, as I want to use it as two channel monoblock for bi-amped system.
For stereo operation, I will come up with a support platform, containing PS and volume control with source switcher. I want to be more original this time;) and don't want to lower the amp's performance with a standard plastic pot.
Also titanium, aircraft screws are used. |
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| Cradle22 |
What is the small input cap you use? Not the BG you used in your amps before, but what else?
I like the approach of using more wood. Even if it means using some additional shielding material. For a cheaper approach I just used on an amp of mine some oak shielded with cheap PCB material (those PCB-material meant for etching your own boards, just without etching).
Wood is great. Even I can work on it ;) I've got two left hands when it comes to metalworks.
But what I also like is the concept of using a thick metal bar in the middle of the amp. Never thought pf that before (normally everybody attaches power devices to the "outside walls" of an amp, with inverted symmetry for stereo amps. This approach is nice.... |
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| Peter Daniel |
Coming back to Thorsten quote:
| quote: | Originally posted by Kuei Yang Wang
And then change the external Powerpack to 4 X 12V/7AH++ SLA Batteries, plus charger. Oh, and fit Autoformer TVC's as Volume controls.
Now THAT would likely be an Amplifier I'd just LOVE to test for an extended period for you.... ;)
Sayonara |
I will also be using batteries and TVC's with this amp, so basically your wishlist is fulfilled. The only thing missing is C37 laquer, but this you could do yourself, when playing with the amp.
And if you would decide on a review, there shouldn't be any confilct of interests, as this amp is non inverting;)
Jokes aside, thanks for good suggestions.:wiz: |
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| Peter Daniel |
| quote: | Originally posted by Cradle22
What is the small input cap you use? Not the BG you used in your amps before, but what else?
I like the approach of using more wood. Even if it means using some additional shielding material. For a cheaper approach I just used on an amp of mine some oak shielded with cheap PCB material (those PCB-material meant for etching your own boards, just without etching).
Wood is great. Even I can work on it ;) I've got two left hands when it comes to metalworks.
But what I also like is the concept of using a thick metal bar in the middle of the amp. Never thought pf that before (normally everybody attaches power devices to the "outside walls" of an amp, with inverted symmetry for stereo amps. This approach is nice.... |
IMHO, this approch is so far the best for that type of amp. Since I didn't want to copy 47Labs this time, the concept of center bar divides the amp again into halfs and seem to be better from resonance control view. Instead of bronze one can use copper and the front and rear panels could be made out of standard, preanodized, 1/8" bars available from HD. The wood adds a nice touch and works as capacitors support as well. This amp's character borrows more from tube equipment chassis materials and it can also be observed in its sound. It doesn't posses this aluminum glare and the silence between notes seem to be deeper. It is very smooth sounding right from the beginning. And for proper performance those BG need at least 24 hours.
I'm not using any small coupling caps. Signal goes directly through 244 ohm Vishay to + input. Feedback is 22k Caddock, another 22k vishay from + to ground and temporarily (for lack of anything better around) 655ohm Holco setting the gain. |
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| Netlist |
This is jewellery!! :)
The colours of all different materials fit so well together. :cool:
I never did the effort to listen to differences between materials and certainly not the way you do.
How can one describe the sound of rosewood and maple in conjunction with bronze, copper and silver?
Only two possibilities: One must have extremely good ears or the perception is the main factor. Just guessing.
You must have both of them and clearly also the skills to build those extremely beautiful amps.
When you describe those different materials sound-wise, you must have compared them to each other and other materials as well. Which I know you did for most of the electronic parts. But now also the case parts?
This is astonishingly nice.
Oh, and make sure the mains cables are well burnt in before testing :devilr: (Just couldn’t resist ;) )
/Hugo :) |
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| zygibajt |
Great Work Peter!!!
Hey,paint it with dammar at least (if you don't have C37).
you can get it at every artist's store.
Bartek |
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| zygibajt |
Peter, there is a cap. on the picture in post #4.What is it's purpose?
You say there is no input cap ,maybe that's Zobel from the output to ground?
Bartek |
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| Peter Daniel |
| That's a Vishay resistor (VTA 55 or somehting similar) setting 22k input impedance. |
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| wormturns |
Very, very nice work Peter!
| quote: | | I will also be using batteries |
Just wanted to mention that several people using battery clones reported best results using film caps ~10uf(or less) for rail bypass when using batteries.
Scott |
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| Peter Daniel |
| Here's one more interesting pic, showing perfect symmetry;) |
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| Peter Daniel |
I switched to batteries now, and although I said in the other thread that I wasn't impressed that much, after listening again for a while, I have to admit that there is something to the sound of the amp running on batteries. It sounds like nothing else and the music seems to be very effortless. The detail is improved and everything seems to be harmonically right and coherent. The effect similar to using an air suspention platform. Nothing really to complain about. Also, the bass is deeper.
I just listened to The Wall CD (the first one) and on track 10, 50 sec into it, a girl says "Hello". Right after that there is an echoing voice in left channel saying "Hello" again, sort of washed out with the music. I've never noticed it before. If Combat 84 will sound as good as well, I think I will switch to batteries permanently;)
I noticed that sometimes TVC seems to sound a bit dull (in the highs) on certain recordings, but with this amp it works fine on everything. Mind you, the BG are not even recharged completely yet;) |
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| ronc |
OK guys, even though i am an old time speaker builder i have no idea what C37 is?Is its purpose to dampen vibrations?
Hay Peter is the hold down bar on the chips Cu, brass???I played around and finally(as finally as anything i do LOL) settled on Poly but am always open to suggestions.
ron
BTW! Peter, good engineering. Form follows function.Like the center H/S and good flow. |
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| jam |
| .......now batteries. Just shoot me, will you..............:D :D :D |
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| Peter Daniel |
Hey jam, get me a gun and I'll shoot you;)
The bar on the chip is copper. I didn't experiment with that, but since it worked on monoblocks I decided on same approach here. I like the shielding properties of copper, and I wanted to use natural materials, not man-made;)
I'm not sure about C37, but I presume it's a sort of violin laquer improving the sound, but I've never tried it yet. Do google search, you'll find enough info.
I played whole evening using batteries and I think I start to like them. Lyrics seem to be much easier to uderstand, especially for someone who's listening to all sorts of music;)
But I still don't feel that comfortable with batteries. What happens after they run out of voltage (unevenly)? Any DC offset danger?
Since I'm using 2 of them in series, I have to figure out a convenient way to charge. I think they could be charged in series as well, by 24V charger?
New amp, TVC and batteries seem like a winning combination. Kuei was right.... |
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| ronc |
No danger to the speakers, it just starts to distort like crazy.
ron |
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| advance |
Hello Peter
| quote: | | I switched to batteries now, and although I said in the other thread that I wasn't impressed that much, after listening again for a while, I have to admit that there is something to the sound of the amp running on batteries. It sounds like nothing else and the music seems to be very effortless. The detail is improved and everything seems to be harmonically right and coherent. The effect similar to using an air suspention platform. Nothing really to complain about. Also, the bass is deeper. |
Welcome to the club. I use batteries in preamplifiers and amplifiers for ages and today I never ever would return to any other power supply for audio applications.
| quote: | | Since I'm using 2 of them in series, I have to figure out a convenient way to charge. I think they could be charged in series as well, by 24V charger? |
I use a very simple charger design with great success. This design may fit your requirements.
Charger Schematic Diagram: http://home.tiscalinet.ch/cooltune/...MCLP-BSU1aS.pdf
Power Supply/Amplifier Block Diagram : http://home.tiscalinet.ch/cooltune/...lockDiagram.pdf
The complete amplifer article: http://home.tiscalinet.ch/cooltune/.../Megalith01.htm
advance |
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| advance |
... and by the way Peter,
Your gainclone design looks very impressive. Congratulations.
advance |
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| Flemming J P |
This is totally unfair. :dodgy:
I am just lurking around, planing to use all the good tested ideas and only doing a minimum work and testing myself :cool:
First it was the AX clone. (never really got started with the project (got the prints), don't understand it enough). Then it was the IGC in all the shape and colors it went through and the resistor war.
When you just thought everything was worked out, Peter destroys it all be using different materials in the chasing which caused changes to the sound. :dead:
Then all of the sudden the non inverting GC was a hit (yes it is a lot easier to integrate into systems) and now I had just build my prototype IGC's.
Then a few days later my BUF634 preamp got absolute, due to some rather expensive trafo's.
And just for the fun of it you add batteries :bawling:
But anyway thank you for all that testing and sharing your finds, you make it so simple for us (me anyway) that one just have to build it.
/Flemming
To do list:
Rebuild my 4 mono IGC's to GC's.
Design and build an active XO (currently using a non DIY... yak)
Build new boxes for my speakers (jbl2225 sealed + fe206e OB)
Redesign IV and output stange on my non os 2x1541S1 dac.
Build the powersupply for the CD-PRO2.
Rob somebody so that I can get those trafo's for a new preamp. |
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| tbla |
| quote: | | Rob somebody so that I can get those trafo's for a new preamp. |
i have some trafos - but they are very expensive.....:D |
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| protos |
| quote: | Originally posted by Peter Daniel
But I still don't feel that comfortable with batteries. What happens after they run out of voltage (unevenly)? Any DC offset danger?
Since I'm using 2 of them in series, I have to figure out a convenient way to charge. I think they could be charged in series as well, by 24V charger?
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You won't get much offset if the rails are 1 or 2 volts out.I had a bigger problem when I attached a battery voltmeter to one just to one battery to check the state but the meter was drawing apparently more than 70ma and drained the battery.However I didn't have problems with the speaker.
A battery charger can be as simple as one lm 317 current regulated only for about a tenth or a fifth of the Ah of your batteries.It is not absolutely necessary to add a voltage regulator as well unless you plan to leave the charger on continually as a trickle charger because you don't want the batteries to draw too much current all the time.
I guess you could use a generic 12v charger off the shelf for all the batteries.I was thinking off the top of my head that this could be possible if you add diodes at the connections between the batteries so that you wouldn't short the charger when connected in parallel. |
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| antomas |
Hi Peter, compliments for your new masterwork!
| quote: | | But I still don't feel that comfortable with batteries. What happens after they run out of voltage (unevenly)? Any DC offset danger? |
I'm not an expert on that, but I think that If the current flowing thru the ground line is little, you could use a rail splitter (precision voltage divider) to balance the voltages:
http://headwize2.powerpill.org/images2/opamp20.gif
This technique is used in several diy portable headphone amplifiers. Please note the TLE2426 has a maximum rating of 40V, so not useful here. Not sure, but I think a power opamp with a couple of precision resistors could be used for the same purpose.
Hope it helps,
Massimo |
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| carlosfm |
| quote: | Originally posted by antomas
Not sure, but I think a power opamp with a couple of precision resistors could be used for the same purpose.
Hope it helps,
Massimo |
Yes, a (unity-gain stable) power op-amp does it.
Like the Burr-Brown ones.
Divide the voltage with two resistors and buffer the virtual ground.
And connect all the batteries in series.
Say goodbye to differences between rails.;)
Nice jod, Peter, as usual.
NASA will contact you.:D |
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| zygibajt |
| quote: | | Signal goes directly through 244 ohm Vishay to + input |
Peter ,what is the purpose of this resistor?
I have noticed on my GC (the same layout accept this resistor) that when there is no source and no cable connected to the amp the DC offset is 200mV (speakers connected to amp are cracking and humming).When I plug the preamp in it is about 30mV and speakers are dead silent.I think DC offset in both cases should be the same.
Any one has idea ,why it is so?
Bartek |
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| GregGC |
| quote: | Originally posted by zygibajt
I have noticed on my GC (the same layout accept this resistor) that when there is no source and no cable connected to the amp the DC offset is 200mV (speakers connected to amp are cracking and humming).When I plug the preamp in it is about 30mV and speakers are dead silent.I think DC offset in both cases should be the same.
Any one has idea ,why it is so?
Bartek |
With my limited expertise the possibilities are:
1. Noise in the input. Without cable connected the input is not shunted by the low output impedance of your source/preamp and more susceptive to noise.
2. There is a change of the DC component at the input of the GC. It would happen if you don't have input cap and your source/preamp has low DC impedance.
This is just a speculation because I don't know your exact sch. |
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| UrSv |
| quote: | Originally posted by zygibajt
Peter ,what is the purpose of this resistor?
I have noticed on my GC (the same layout accept this resistor) that when there is no source and no cable connected to the amp the DC offset is 200mV (speakers connected to amp are cracking and humming).When I plug the preamp in it is about 30mV and speakers are dead silent.I think DC offset in both cases should be the same.
Any one has idea ,why it is so?
Bartek |
It's called oscillation and could kill your speakers as well as your GC. |
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| ronc |
DC offset will not cause hum or static of any kind.It will move the cone to a given position and the incoming sine wave will have to exceed the DC offset voltage for the cone to move from that position.
ron |
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| hitsware |
| FWIW ..... An op-amp with assymetrical supplies (as long as they're within proper operating range) still centers on 0volts (assuming the inputs are there) The output does not reflect offset in the rails.........mike |
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| zygibajt |
Thanks guys,
Then what can be wrong???
My setup is:
2*19VAC power transformer
double MUR860 bridges
2*1000uF Panasonic FC caps (directly on the chips)
22K feedback resistor
- input connected with 680R to ground (no cap here)
+input connected through 22K resistor to ground.
I tried to put 220R resistor in series with + input,nothing changes.
When I put 4uF coupling cup the DC offset got to -200mV ,but speakers are silent.
It looks like this:
The speakers and preamp connected:about 30mV offset and dead quiet.
I disconnect the cables from preamp to GC:
There is -200mV offset (how come minus?)
and there is a big humm in the speakers.
Bartek |
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| Peter Daniel |
My Dac is AC coupled. If I don't have the resistor at the input, and the potentiometer is at the max volume (effectively no series resistance) the oofset jumps from 30mV to 200mV and there is a noise in speakers. I'm using 244 ohm resistor to take care of that particular situation.
Also, the Caddock in FB might be a bit hrash sounding. Vishay S102 brings better tonal balance, as they always sounded very soft. |
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| Peter Daniel |
| quote: | Originally posted by zygibajt
Thanks guys,
Then what can be wrong???
My setup is:
2*19VAC power transformer
double MUR860 bridges
2*1000uF Panasonic FC caps (directly on the chips)
22K feedback resistor
- input connected with 680R to ground (no cap here)
+input connected through 22K resistor to ground.
I tried to put 220R resistor in series with + input,nothing changes.
When I put 4uF coupling cup the DC offset got to -200mV ,but speakers are silent.
It looks like this:
The speakers and preamp connected:about 30mV offset and dead quiet.
I disconnect the cables from preamp to GC:
There is -200mV offset (how come minus?)
and there is a big humm in the speakers.
Bartek |
With interconnect connected I have 10mV and 20 mV in ea channel respectively.
When I disonnect it I got 50mV and 80mV (I didn't check for polarity). Your 200mV seems normal and I noticed before that some chips present more offset than others. I once had a chip which in particualr NI setup produced 400mV (no 22k to ground) and when I replaced it with the other one, I got 170mV of offset. So don't worry, just keep the cables connected all the time;) |
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| zygibajt |
Thanks a lot for that informations
Just half an hour ago I checked everything once again.
I put that 220ohm resistor in series with + input and I think I leave it there becouse it seems not to change the sound (opposite than with putting input coupling cap).
It's not the offset that I'm worring about but the noise in speakers when I unplug the input cables.
I remember from Aleph expirences that DC offset stayed the same either input cables were connected or not ,and there was no noise in the speakers either.
Do you have any noise in the speakers when You plug the amp in without input cables connected?
My GC is an open design (no enclosure) for now so that may be the couse. |
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| Peter Daniel |
| When I disconnect the cables at amp's side, no noise. When the cables are disconnected from the preamp (and connected to amp) I get noise in the speakers. It was the same for inverted amp and I think it's normal. |
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| carlosfm |
zygibajt, it seams that you have a ground loop there...
Can you test only one channel?
Do you have one or two PSUs/transformers?
If only one, you have to put the two channels (chips) very close one from the other, and join the two star grounds with a very small piece of wire. |
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| zygibajt |
Thanks again Peter
There is always noise when one disconnects cable at preamp side,but I have a noise when I disconnect the cables at amp side leaving only amp and speakers connected.
Something must be wrong,but it seems my schem. is identical to yours ,now.
Hmm.. |
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| zygibajt |
Thanks Carlosfm
Maybe ,but with amp connected to preamp there is absolutely no hum in the speakers (usually in case of loops there is).
Also I converted the IGC to NIGC without changing grounding schem. and IGC didn't have that noise.
I will try one channel later (I have to go out ,now)
Bartek |
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| GregGC |
Bartek,
What's your exact schematic?
"Just half an hour ago I checked everything once again.
I put that 220ohm resistor in series with + input and I think I leave it there becouse it seems not to change the sound (opposite than with putting input coupling cap)."
I hope you ment (and you used) 220 kOhm rather 220 Ohm. |
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| Cradle22 |
Hi!
| quote: | Originally posted by Peter Daniel
I once had a chip which in particualr NI setup produced 400mV (no 22k to ground) and when I replaced it with the other one, I got 170mV of offset. |
That made me wonder... I have read about stuff like this before, and also experienced it by myself on my GC stuff.
If it comes to actually manufacturing something like the LM3875 or OPA 549... I think the process could be compared to manufacturing a computers processor.
And from those I know that for example position of the die for each chip on the big wafer, and also experience in building that particular chip matters in terms of quality of the resulting processor (for example, the frequency with which it can be run).
And we all know of transistors having different measurements (therefore the "matching" of output & input transistors).
:confused: :confused: :confused: :confused: :confused: :confused:
And so I just wondrered: Has anyone ever experienced sonic differences / variations because of those manufacturing processes?
Would it be advisable to "match" / measure chips used for GCs?
Bye,
Arndt |
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| darkmoebius |
Rod Elliot of ESP has provided an easy design that does it all.
Introduction
For those who want the cleanest possible DC for sensitive preamps, battery power is ideal. At last, remembering to turn the charger back on is no longer a problem!
This project is one for the experimenter, but as shown will work extremely well. The sensing circuit can be made so sensitive that a load of only 2.5mA is enough for the circuit to detect, and disconnect the charger.
The idea is that the charger is left permanently connected, but of course that would normally introduce some hum into the supply lines. The sensor detects that you have switched on the preamp (or small power amp for that matter), and immediately switches off the charger, so while listening, there is no connection to the AC. Although it is possible to use a "solid state" switch, these are not as good as a standard relay, which provides perfect isolation of the AC input.
Elliot Charger |
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| stelios |
I often wonder if the choice of case materials isn't just as important as the dimensions and shape of the case. After all resonance behaviour is controlled by both the dimension/shape choices as well as sound velocity of the medium.
To that effect, the position of the amp chip on the bar would matter eg. centered vs. off-centered, as well as the size and material of the screws, torque (of course), shape of the "bar" (eg. a disk, or cylindre vs. a rectangular bar) etc.
I also wonder what it would sound like (in this implementation) if the wooden sides were eliminated and the thin perf. aluminium was used there instead - ie. an overall simpler design more akin to that of a tuning fork with possibly a stronger sonic character but better ?
Going along this (even more expensive experimental) route I would be tempted to try and subjectively correlate the amps sound with that of the case when eg. knocking on it or performing some other sonic test on it.
Perhaps instrument builders would have more to say on these matters.
Well this approach would probably lead us fast in the region of diminishing returns and would be quite impossible to pursue without some quantitative research done first and a method established with the aid of suitable software for example (Excel, or other freeware).
Lastly I noticed here a switch to magnet wire for the internal wiring - this is sth I've "decided" to use as well on the second amp I'm making (more a result of having nothing else available actually) and I'm wondering what the difference will be.
Stelios |
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| grataku |
Peter,
you make delicious little pakages that look almost good to eat but I think it's time to break through the glass ceiling which you have quite obviously reached.
I.E. It's time to try a better circuit dude! |
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| Peter Daniel |
| quote: | Originally posted by grataku
I.E. It's time to try a better circuit dude! |
Any suggestions? |
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| tbla |
| ...very tastefull peter, mail me an offer - only the amp and not the ext trafo....:) |
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| Peter Daniel |
| quote: | Originally posted by tbla
...very tastefull peter, mail me an offer - only the amp and not the ext trafo....:) |
You understand that just 4 electrolytics are about $300?;) |
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| tbla |
| quote: | | 4 electrolytics are about $300 |
...and people say that my prices are too high....:D
ok, i'll take the empty box incl. the cardas b posts.....
btw how come you don't use cardas rca femaleplug...? |
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| Peter Daniel |
Because Kimber is more expensive and I kept them for special occasions. I'm not that sure about it, but whenever I tried Cardas it seemed to add very soft character. Sometimes I think that Chinese (tiffany knock offs) are simply better.
I'll be building few more boxes with copper inside and aluminum on the outside. I could offer them for sale then. They will also be slightly lower (2" vs. 2.5") for better looks. |
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| tbla |
| ok, let me know when you have it ready....:) |
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| analog_sa |
| quote: | | tried Cardas it seemed to add very soft character. |
My experience exactly. I still like them but wouldn't mind something with slightly less euphonic character. Any suggestions?
| quote: | | Also I converted the IGC to NIGC without changing grounding schem. and IGC didn't have that noise. |
The IGC is inherently more stable so it's quite possible after the conversion you get oscillations.
| quote: | | Excel, or other freeware |
Oh, me God! Hope that Gates dude isn't cruising the forums looking for an amp to build. |
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| stelios |
| quote: | Originally posted by analog_sa
Oh, me God! Hope that Gates dude isn't cruising the forums looking for an amp to build. |
The new version of windows comes with an amp built in {it's called "winamp"}. It will be an amp better than any other amp before it (until the next windows upgrade that is). |
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| Peter Daniel |
| quote: | Originally posted by analog_sa
My experience exactly. I still like them but wouldn't mind something with slightly less euphonic character. Any suggestions?
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Normally I use those Chinese Tiffany imitations, I buy at $2.5, and they seem to sound not that bad. Otherwise, Kimber seems to be fine, but it's quite expensive ( $26). I understand that plating on Kimber is thicker and it also seems to be very tight when attaching male connectors. |
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| Peter Daniel |
| quote: | Originally posted by stelios
I often wonder if the choice of case materials isn't just as important as the dimensions and shape of the case. After all resonance behaviour is controlled by both the dimension/shape choices as well as sound velocity of the medium.
To that effect, the position of the amp chip on the bar would matter eg. centered vs. off-centered, as well as the size and material of the screws, torque (of course), shape of the "bar" (eg. a disk, or cylindre vs. a rectangular bar) etc.
I also wonder what it would sound like (in this implementation) if the wooden sides were eliminated and the thin perf. aluminium was used there instead - ie. an overall simpler design more akin to that of a tuning fork with possibly a stronger sonic character but better ?
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I would imagine that in my case the most critical area is the barr attaching chip to the chassis. I didn't experiment with that, but both the material and the torque on the screws certainly affects the chip (I'm cautious enough not to say sound;). I used the minimum torque on my screwdriver to be safe. |
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| stelios |
| quote: | Originally posted by Peter Daniel
I would imagine that in my case the most critical area is the barr attaching chip to the chassis. I didn't experiment with that, but both the material and the torque on the screws certainly affects the chip (I'm cautious enough not to say sound;). I used the minimum torque on my screwdriver to be safe. |
I remember a while ago you were posting about the differences between insulating pads. So I thought different torque settings will have different damping effects. I guess after a certain point the amp would sound rather strained ;) (Btw what are these pads in this picture ? Did you cut them from a larger sheet ?)
Anyway, my whole post was generated from a thought I had yesterday while I was deliberating how I would cut sections from some pi-shaped aluminium extrusion off-cuts I had lying around to optimally built the sides of a box based on a large heatsink. While doing that I was flicking them with my fingers to get that 'ping' sound and noticed they sounded different.
And the rest as they say is history... (or, in this case, maybe it isn't ;)) |
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| hifi |
Well.. migth be time to try a amp not so sensitive to just about everything?...aaaagh why are you chasing me with tar and feathers =)
Is there any successor to the LM3875 from Linear themselfs on the horizon?
/ micke |
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| Peter Daniel |
Those are silpads and I cut them from TO-3 insulator.
I don't think there are non-sensitive amps. I was experimenting with Aleph and the material used under the feet made very big difference as well. |
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| GregGC |
| quote: | Originally posted by Peter Daniel
I would imagine that in my case the most critical area is the barr attaching chip to the chassis. I didn't experiment with that, but both the material and the torque on the screws certainly affects the chip (I'm cautious enough not to say sound;). I used the minimum torque on my screwdriver to be safe. |
Peter,
I'm sure you thought about it, but I'll mention it anyway.
I'm not too crazy about that kind of attachemen to the heat sink as the chip starts heating up the plastic will start expanding and ..... crack. And if not "crack" at least a lot more compression on the chip inside. Unles you have some kind of spring-loading construction.
Greg |
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| Peter Daniel |
| That's a method used by many manufacturers and if they still use it, I don't expect any cracking. I was hesitant also, but after trying in monoblocks, I didn't notice any degradation in sound, but rather improvement, so I continue to use it. |
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| stelios |
| quote: | Originally posted by hifi
Well.. migth be time to try a amp not so sensitive to just about everything?...aaaagh why are you chasing me with tar and feathers =)
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I was going to report you to the moderator but I'm feeling kind today...| quote: |
Is there any successor to the LM3875 from Linear themselfs on the horizon?
/ micke |
well I don't know about you, but I'm listening to Elgar thru my crappy PC speakers which I collected from the corridor after someone decided to get rid of them and I'm telling you, they sound a-mazing ! (for the price) I'm not joking: for natural instruments and voices they're killers.
I've been trying to find out what brand the 3" paper cone drivers inside are without success. The stereo chip amp inside looks bog-standard and the power supply - well, let's not even discuss that. If you pester me enough, I'll open them up and have a look at the chip for you. In fact the only thing I think is bad about them is the placky box which rings. The make is "Typhoon" "sound system" btw. With a bit of luck you might find a pic on the web (not in their site.)
| quote: | Originally posted by GregGC
I'm not too crazy about that kind of attachemen to the heat sink as the chip starts heating up the plastic will start expanding and ..... crack. And if not "crack" at least a lot more compression on the chip inside. Unles you have some kind of spring-loading construction.
Greg |
Call me a cynic but I'm sure the people who are employed to design the chip case have thought about that. Otherwise the chip would "explode/crack" from it's own heat. Besides, if you're worried, use a low torque setting like Peter does and add another silicone insulated pad in between... |
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| GregGC |
| quote: | Originally posted by stelios
Call me a cynic but I'm sure the people who are employed to design the chip case have thought about that. Otherwise the chip would "explode/crack" from it's own heat. Besides, if you're worried, use a low torque setting like Peter does and add another silicone insulated pad in between... |
I know manufacturers use it and I'm not saying it's not going to work. Sure it provides more even preasure distribution over the chip. I just think that the implementation have to be very careful (not that Peter isn't) and maybe there is a bit more hidden stuff behind a picture. Like you suggested, double insulating pad or speciffics about the torque used or bracket material or .... |
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| stelios |
| quote: | Originally posted by GregGC
Like you suggested, double insulating pad or speciffics about the torque used or bracket material or .... |
I'm probably wrong, but I think I've seen datasheets providing these "max torque specifics" for some semis.. I'm probably wrong...
I was thinking of tightening them enough till they crack so I would then know actually.... |
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| hifi |
Hello,
I´m well aware of the GC:s quality ... just messing with you guys,
Anyway I´m contemplating building the Tube buffer by JLTi. maybe something for you to try?...("you" applies to anyone with a GC)
/ micke |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by stelios
I often wonder if the choice of case materials isn't just as important as the dimensions and shape of the case. After all resonance behaviour is controlled by both the dimension/shape choices as well as sound velocity of the medium.
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Of course. Dimensions matter as much. I will only mention here again that occult studies and occult numberology can give amazing insights.
Did you know that the movements of ALL Planets can be represented as notes on the primitive tonal scale? They don't make notes in the well tempered scale.
Music of the crystal spheres? Occult numberology and audio? Study of the Metals and origins?
You bet. Sounds like the seven hermetic arts to me.
Sayonara |
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| zygibajt |
| quote: | | I hope you ment (and you used) 220 kOhm rather 220 Ohm |
I ment 220 ohm on +input,just to put some resistance on input.
Peter said he used 244ohm Vishay there.
220kohm - why???
I figured that my problem is some kind of microphonic/RFI/grounding oscillations.When I move my hands around the input RCA's and star ground point the noise modulates.
Bartek |
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| GregGC |
| quote: | Originally posted by zygibajt
I ment 220 ohm on +input,just to put some resistance on input.
Peter said he used 244ohm Vishay there.
220kohm - why???
I figured that my problem is some kind of microphonic/RFI/grounding oscillations.When I move my hands around the input RCA's and star ground point the noise modulates.
Bartek |
If you are reffering to IGC 10k/220k with input cap, the closer to 220k the resistor from +In to GND the lower the output DC offset will be. The concept is described here :http://www.diyaudio.com/forums/show...9680#post259680 though it refers to NIGC.
Greg |
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| zygibajt |
| I'm talking about non inverted GC here. |
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| lohk |
No Greg, here you are way off.
The method of mounting Peter uses here is also used by many manufacturers (like Naim) and is the better mounting method in most cases. The chip is bended less (very importand with broad ones like the LM) than mounted with a screw, the overall contact to the surface is better. The plastic case does not "expand" that much, not even in case of burning through. It is although necessary that the mounting force is substituted evenly on the surface, it is done normally by using non-bending blocks and a torque wrench.
Klaus |
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| Bratislav |
| quote: | Originally posted by Kuei Yang Wang
Did you know that the movements of ALL Planets can be represented as notes on the primitive tonal scale? They don't make notes in the well tempered scale.
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Can you tell me what notes do Neptune and Pluto do ? Cause their orbits intersect. And what note do Ceres, Vesta, and millions of other minor planets do ? Must be rather cacofonic.
How do you pick a note for a highly eccentric orbit like Mars' or Pluto's ? Or for a planet whose perihelion constantly shifts, like Mercury ?
| quote: |
Music of the crystal spheres? Occult numberology and audio? Study of the Metals and origins?
You bet. Sounds like the seven hermetic arts to me.
/B] |
Sound like lots of c#@p to me.
Glad guys like you are not designing my gas supply. Or brakes in my car. |
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| Peter Daniel |
| quote: | Originally posted by Bratislav
Glad guys like you are not designing my gas supply. Or brakes in my car. |
And I'm happy that guys like you post only occasionally in a Chip Amps forum.;) |
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| Bratislav |
| quote: | Originally posted by Peter Daniel
And I'm happy that guys like you post only occasionally in a Chip Amps forum. ;) |
Only here to please :) |
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| Peter Daniel |
| At least your sense of humor is fine;) |
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| Alex S |
| quote: | Originally posted by GregGC
I'm not too crazy about that kind of attachemen to the heat sink as the chip starts heating up the plastic will start expanding and ..... crack. And if not "crack" at least a lot more compression on the chip inside. Unles you have some kind of spring-loading construction.
Greg |
actually, as the thing heats up there'll be less compression 'cuz the metal bolts (longer lengths needed in this sort of arrangement) expands more.
So spring washers (nice beryllium copper ones are cheaply available) are useful, not to ease pressure, but to maintain it over the heat cycles. |
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| ofb |
| quote: | | Alex S: actually, as the thing heats up there'll be less compression 'cuz the metal bolts (longer lengths needed in this sort of arrangement) expands more. |
you sure? as heat source, the chip is going to be warmer than the bolts off to the side. not much, but enough to compensate for the expansion difference perhaps? and what about the increasing thickness of the plates taking up some of the increasing length of the bolts? (or is that in the southern hemisphere?)
seriously, i'm not much worried about this and am just following along with an interesting quibble. i suspect that the chip is only in danger if the bolts are cranked down too tight; if stressed near fracture, the heating and cooling cycles will likely finish it off in a manner more akin to fatigue than one-time overpressure.
i do like the idea of a sprung system for high end amps though. maybe that can be taken care of more directly by careful selection of bolt and plate material & dimensions alone. plus keeping in mind you want springs that will keep sufficient tension throughout the temperature range.
(yes... i'm just going to tighten my own bolts down till they feel right. but if we must quibble, let's have a good run with it.) |
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| BTW |
| The clamping bar on top of the chip actually becomes a heat sink as well and heat transfer is further improved . So IMO thermal expansion of the chip is not an issue. |
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| Peter Daniel |
That's how Rowland does it.
It would never occur to me that a chip could break because of it mounted this way. I once tried to break the chip myself, to see how the connections run inside. Believe me, it's not an easy task;) Even if it expands, I would first see the bolt heads making dimples in a copper bar, the bar bending, the pad compressing, the thread giving out, before the chip breaks. This is a flexible assembly and it can't damage the chip. |
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| analog_sa |
| quote: | | Music of the crystal spheres? Occult numberology and audio? Study of the Metals and origins? |
Strong opinions from someone who religiously applies C37 every full moon. Is that so different from proportioning an amp case for least vibration? |
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| Alex S |
blurb:
"A range of beryllium copper crinkle washers in both metric sizes. These washers have good corrosion resistance, are non-magnetic, and have high resistance to permanent set under compression. They have a number of uses including use as vibration-proof locking washers that will not mark or damage panel surfaces." |
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| carlosfm |
| quote: | Originally posted by Kuei Yang Wang
Konnichiwa,
Of course. Dimensions matter as much. I will only mention here again that occult studies and occult numberology can give amazing insights.
Did you know that the movements of ALL Planets can be represented as notes on the primitive tonal scale? They don't make notes in the well tempered scale.
Music of the crystal spheres? Occult numberology and audio? Study of the Metals and origins?
You bet. Sounds like the seven hermetic arts to me.
Sayonara |
:eek:
Gotta buy a gold bar from a swiss bank and try it as a heatsink for my GC.:D
Kuei, let's drink a beer, I'm getting a little lunatic with all this.;) |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Bratislav
Can you tell me what notes do Neptune and Pluto do ?
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I have done the calculations only for the seven "classical" planets found in occult philosophy. And they match precisely.
| quote: | Originally posted by Bratislav
Cause their orbits intersect. And what note do Ceres, Vesta, and millions of other minor planets do ? Must be rather cacofonic.
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Who knows. Maybe Philip Glass designed it all?
| quote: | Originally posted by Bratislav
How do you pick a note for a highly eccentric orbit like Mars' or Pluto's ?
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Notes are just expressing a frequency. Like A is nowadays reckoned to be 440Hz, but should really be 432Hz. How do you get a frequency from the orbit of a planet? If you have to ask you will never "get it".
| quote: | Originally posted by Bratislav
Sound like lots of c#@p to me.
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Maybe. That is your perogative.
| quote: | Originally posted by Bratislav
Glad guys like you are not designing my gas supply. Or brakes in my car.
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Hmm. Maybe you are. Maybe you would still be better of if we did.... You see, you never actually TRIED it, you simply reject things out of hand because you fail to understand them. Setting oneself up the yardstick of all knowledge is a dangerous position to be in.
Sayonara |
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| tbla |
| batteries......!!!!!!here's what you should try peter - REGULATED SUPPLY.....i use lt1083 + pedja's scematic and 10.000 uF cerafine + wima fkp3 before reg and silmic 470 uF / 63 V after the reg close to powerchip........the regs could easily be placed on each side of the lm3875 on the broncebar.......:) |
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| stelios |
| quote: | Originally posted by Kuei Yang Wang
Konnichiwa,
Of course. Dimensions matter as much. I will only mention here again that occult studies and occult numberology can give amazing insights.
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Well, I don't know much about that. What I'm suggesting is not different than the resonance behaviour patterns of a room. Or the general acoustic properties of a room. You only have to make the room smaller, perhaps a funnier or simpler shape, and fill it up with copper/bronze/brass whatever instead of air. The software, reports, technology is there. So it might be worth investigating or it might not. But if we're concerned with harmonic content, spectra, behaviour etc. I think it might.
Or it might just lead to a different avenue yet. Why do bell makers make bells the way they do ? Why do they choose one material over another ? Why do I hate the ones they have at college and like the ones at my village ?
Why are most guitars not square and why some of them are ? There's more questions than answers no doubt but there's surely some (already worked out) answers too. It's a question of how much time you want to spend on it. (I obviously prefer spending my time ranting ;))
Stelios |
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| ronc |
Well we all can just build better amps but the thing is the source goes > amp >speakers > room.
Most ppl never realize what the room does to the sound. I myself have bass traps, mid traps and high traps. I went thru a lot trying to get the correct sound and have finally gone with gainclones fostex fe-166e horns(single driver full range, horns tuned to 50hz).The IGC and TDA 1524a pre are battery powered and the only P/S caps are 6.8uf mylar.
As i have a buyer for the horns/GC combo (my dentist, hay i will get some of my money back)I am going to go to Fe-108e horns,tuned to 57Hz, and NIGC but all will still be battery powered.
ron |
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| tbla |
hey, thats not legs - but you'r just a guy with 4 arms...:bawling:
btw is that an italien t-shirts you are wearing - there's spagetti sticking out from the sleeves.....:bawling: :bawling:
ok - somebody stop me, no more jokes.....:clown:
i'm pretty shure that your system sounds very good and it looks good too......:) |
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| planet10 |
| quote: | Originally posted by ron clarke
Most ppl never realize what the room does to the sound. |
I was in the fortunate position to have been able to start my hifi by designed my listening room :)
Makes a big difference.
dave |
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| ronc |
Well it aint my best view LOL.This may be OT but has anybody used the argent room lens or clones ?
I see PD has finally gone with Batt P/S (bout time).I am presently running +/- 24Vdc on the P/S as after trying +/- 12Vdc it just didnt give enough response.Thinking about a seperate battery for the pre as it may be contaminating the ground to the pre using the amp batteries.Any ideas or feedback on this?
http://community.webtv.net/roncla/THISISME
ron |
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| carlosfm |
Some days ago, at a friend's house, I blocked the rear bass-reflex on his Kef Q7 speakers.
Much better now.
Otherwise they would only play well in the middle of the room.:D
And the room is a large one.
Guys, let's talk about audio.
You're flying in the outer space.:D |
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| carlosfm |
Hey Ron,
Everything is very nice, except the t-shirt.:clown:
You should get one from National.:clown:
:angel: |
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| hitsware |
>Everything is very nice, except the t-shirt.
Here he his in his Sunday best :) |
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| GregGC |
Let me make your life a bit more exiting.
I don't mean to start a new war or suggest that one sounds better than the other, but just found out:
OPA541 has 22db better CMRR than the LM3875. |
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| hitsware |
| FWIW ..... I think the PSRR is not quite as good.....?????? |
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| GregGC |
| quote: | Originally posted by hitsware
FWIW ..... I think the PSRR is not quite as good.....?????? |
Strange, I can't find the PSRR in the OPA541 data sheet. |
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| GregGC |
And it should be a lot less prone to oscillations. I may be wrong but it looks like that according to the data sheet (45 deg. more reserve or 10 dB gain reseve at 180 deg. in favour of OPA541). Though at 30dB gain they are both good.
!!! OPA541 has a lot more THD at 0.1W/1kHz compare to LM3875 0.35% vs 0.015%). At 5W and up they are the same.!!! I don't know how vital that is. I suspect it is.
I guess LM3875 would sing better at low volume. Plus with wider frequency response (200 kHz vs. 50kHz at 30dB) will be even better. |
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| hitsware |
| quote: | Originally posted by GregGC
Strange, I can't find the PSRR in the OPA541 data sheet. |
I don't see it either.......Guess I was thinking of the 549 .... |
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| ronc |
LOL geee Mike hahahahahaha.
Really i kinda like the shirt (in a warped kinda way)
ron |
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| travis |
what the name for the connectors you use for the power connections?
i'm looking through a mouser catalogue and i am over whelmed. |
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