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Old 5th December 2006, 09:11 PM   #231
Kooka is offline Kooka  Italy
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Quote:
Originally posted by VLSI
Should I put these in my next GC?
Came from a bit of telecom equipment I recently trashed (also had in it 12x 47,000/50v capacitors as well)



These Nichicon are nice.
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Old 5th December 2006, 09:14 PM   #232
Kooka is offline Kooka  Italy
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Quote:
Originally posted by VLSI
PS rail voltages are +/-42v, I would have liked it a bit lower but I have 12 of these transformers from old computer terminals and wanted to use one.
If you were not on the other side of the world I would have asked you to send here some of these trafos...
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Old 5th December 2006, 10:55 PM   #233
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Quote:
Originally posted by Kooka


You mean that the sound of my GC got worse? I had the opposite impression.


I didn't say anything about the sound of your GC , I've seen several disscussions on caps in GCPSU on this forum, but common concent seems to be that more capacitance improves the amps abilities in the lower frequencies, but also slows it down, ruining the immidiacy (spelled rigth ?) the rythmic flow that makes the original my favourite, in spite of it's obvious problems n the bass area.
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Old 5th December 2006, 11:44 PM   #234
Kooka is offline Kooka  Italy
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Quote:
Originally posted by superhkm




I didn't say anything about the sound of your GC , I've seen several disscussions on caps in GCPSU on this forum, but common concent seems to be that more capacitance improves the amps abilities in the lower frequencies, but also slows it down, ruining the immidiacy (spelled rigth ?) the rythmic flow that makes the original my favourite, in spite of it's obvious problems n the bass area.
Ah, we are at the point: I haeard the same boards without and with the extra caps. The impression is exactly in the way you describe them, but since the improved bass section is clearly audible, and the slowing down of dynamic is really on the little size, I assume one thing: if an amp is lacking in basses but quite dynamic, an improvement in the bass section and a little reduction in dynamicity transalte in a general improvement of sound.
Making a long story short: after hearing the boards without and with the extra caps, I will leave the caps there
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Old 5th December 2006, 11:50 PM   #235
VLSI is offline VLSI  Australia
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I have experimented with capacitor values from 1000uf to 50,000uf and I would have to say that on the whole more is better.
What really seemed to help are 4.7uf 10uf Polypropylene capacitors as close to the chip as practical.
I have built 9 chip amps all different parts and layouts and they all sound basically the same, even with a listening panel of friends (2 of which are using my old GCs full time) agree there is not much difference.
The biggest breakthrough to my ears has to be the LM4702, Even my rough prototype has far better imaging and detail than any GC I have built.
I am very excited about this chip and hope to hear much more from the DIY community.
BTW Just for fun I took the entire front end out of an old LUXMAN 5L15 amplifier yesterday (leaving just the output transistors, driver transistors and VBE multiplier) and replaced it with a LM4702 and the improvement in sound was absolutely incredible.
I have 2x 5L15,s so it is easy to compare them.
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Old 5th December 2006, 11:58 PM   #236
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It may be just a question of taste, in sound and in music.
My nr.1 stereo system is in the familiy livingroom, and plays a lot of acoustic jazz and classical. If I crank up Deep Purple I'm usually in the car, or with headphones in front of the pc.

ps. it may be time to leave this thread for it's rightful purpose..ds.
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Old 6th December 2006, 08:36 AM   #237
billbo is offline billbo  Australia
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Default stk4048XI

My first Chip amp after building a few tube amps and it suprised me very much.
I used the stk4048XI and it behaved perfectly.
I even designed it on vero board and had no troubles at all.
I completed a stereo amp with built in passive pre amp with four inputs.
Extremely easy to build. Very powerful.
I fully documented the project with board layouts and pictures to reconstruct the amp.
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File Type: jpg stk_amp1a.jpg (95.2 KB, 5495 views)
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Old 6th December 2006, 10:46 AM   #238
Nordic is offline Nordic  South Africa
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My_Ref_C being reboxed.
Also upgraded a number of elco caps to low ESR models, ceramics to cog and bypassed some other, and found 2 caps that were 470nf instead of 1nf, which I think explains my previous heat issues.

This rear part slides into a box from the rear... I will post pictures of the box later... just took a small smoke break quickly inbetween installing PCBs.

Click the image to open in full size.

Click the image to open in full size.
The heatsinks 2.5C/W 10cm x 10cm x 5cm x2
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Old 6th December 2006, 12:02 PM   #239
Nordic is offline Nordic  South Africa
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Almost done

Click the image to open in full size.
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Old 6th December 2006, 12:27 PM   #240
VLSI is offline VLSI  Australia
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Almost finished my Bridged LM4780
Just need to remove the old pre-amp and make a timber front panel?
It is built in the chassis of a wrecked KODA 260 amplifier (A2760 in Australia) from DSE.
I was able to use the 300va transformer, 4x 10,000uf filter caps, DC protection circuit and input selector, New heatsinks though as the originals where too small.
The pre amp is disconnected, Just using the volume control till I can get a good quality Alps.
I designed and home made the single sided PCBs
It has a regulated 5A PS (tested limit 7A) using 2x LMS 1585-1.5v regulators protected from capacitor charging inrush and output shorts by 2x 9.1v/50w zener diodes. PS input is 45v output is adjustable with a 10T trimmer in the ground lead and set to 38v.
The sound is very sweet and smooth almost valve like in quality, Probably the best sounding LM3886/LM4780 amp I have built, I really like using this amp.
I have used the amplifier modules before but they have not sounded this good. (Must be the regulated power supply??)
RMS outputs are 75w+75w 8ohm, 110w + 110w 4ohm (voltage regulators drop out with 2x 4ohm load) 75w one channel 8ohm and 140w one channel 4ohm
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