Amp4 Mod Round-up Ė Input wire, power caps and high capacitance speaker cable - diyAudio
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Old 11th March 2007, 12:15 PM   #1
Peteruk is offline Peteruk  United Kingdom
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Default Amp4 Mod Round-up Ė Input wire, power caps and high capacitance speaker cable

Hey all,

Iím coming to the last stages of my Amp4 project, where Iím deciding on some of the perhaps more trivial parts. Iíve already sorted out the input caps (Jensen 2.2uf PIO), output caps (Wima MKP2) and torioid inductors (Metglas Cores). However, there are just a few bits Iím undecided on, and would appreciate any feedback available.

Firstly, the electrolytic caps. While many claim Blackgate are the undisputed champion here, they are indeed a considerable amount of money (that said, I did get Jensen PIO for the input :wink and more importantly, I trust Michael Mardisís word when he says they arenít really suited for this amp. Therefore, after considerable searching, Iím left with generally two choices that seem good for most caps. Firstly, the Elna Cerafine. From what Iíve read about them they offer a good compromise between the Ďnaturalnessí of the Silmic II, and the Ďdirectnessí of the Blackgates, and Iím assuming theyíre suited to this application. My second choice is the Panasonic FM series. While rather less impressive, theyíre still meant to be ideal for this situation, and are rather cheap too. The various capacitor situations and my thoughts on it are as follows:

2x 10000uF 50V Ė These caps I do not need to consider, as theyíre for AC smoothing, which is unneeded with my battery source.

1x 10uF 10v , 1x 1000uF 10v, 2x 330uF 35V Ė These caps can all be Elna Cerafine quite easily. There are several places that sell this size range of them but Audio-cube (although theyíre currently on holiday) have the best range.

2x 1500uF 35V Ė These power supply caps are rather important. However, Iíve found it quite hard to find Cerafines in a suitable voltage/size. Audiocube doesnít stock them, and while the PDF they link to on that site doesnít say that Elna do anything that large (might be old) Iíve seen several 10KuF caps and some 63V ones on ebay in the past, so they must have been made sometime. Anyone any ideas on where I might be able to source these? If all else fails, I could quite happily go for the Panasonics here, probably to be sourced from Farnell UK.


Next issue, is the input hook-up wire. Iíve been convinced using shielded wire is the way forward, as I have a particular noise issue in my ampís to-be home (PC, and various other noise makers). However, thereís still quite a list that I have to choose from. If youíd like to express any opinions on your preferred it would be great.

Weisd - Belden 8442 $1.02 / foot
DIY Audio Store- Oyaide Pa-02 $35 AUS /metre ($27.57USD) (A bit pricey...)
DIY Audio Store- Mogami W2893 $4.25 AUS/metre ($3.35USD) Ė AWG26
Percy Audio - Mogami 2534 - Four conductor (24ga) 6mm D shielded microphone cable OFC Neglex copper $1.15 per foot AWG24
Percy Audio - MUSIC METRE IV A quasi solid core design comprised of four insulated strands, 3x28ga & 1x34ga per + & -, utilizing a high purity Teflon insulated OF copper, foil shield (40pF foot shielded), 7mm DÖ $7.50 mono foot
Percy Audio - Canare Star Quad: The L4E6S four conductor (21ga) 6mm D microphone cable 44, 57pF/foot, black 6mm DÖ 95Ę


Next, Iím considering making myself some new Cat5e speaker cable, specifically VHaudioís DIY project. However, the site does state that they will be of high capacitance, and that this could prove a problem for some amps. Even though Iím not going to be using lengths any long than say 2.5m (and there are Zobel caps in the amp4 design), would this be the case with Tripath amps? If so, what would you advise?

Lastly, Iíve already chosen my attenuator from the bargain one on diyfidelity, but Iím still undecided as to which resistance is best. I remember someone telling me Scott Endler said 10Kohm was preferred, while Vinnie of Red Wine Audio fame prefers 20kohm. Iím not really sure how to judge this.

Oh, and on a side note Ė banana plugsÖwhat are your favourite?

If anyone can offer any advice to help me finish off this project, it would be greatly appreciated.

Thanks to all who post,
Peter
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Old 12th March 2007, 11:02 PM   #2
xenob is offline xenob  Austria
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And, one of the most important questions: What gain will you set for your amplifier?
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Old 15th March 2007, 08:16 PM   #3
Peteruk is offline Peteruk  United Kingdom
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Quote:
Originally posted by xenob
And, one of the most important questions: What gain will you set for your amplifier?
Good question.

I have 2 sources that I will be using with this amp - firstly, an ipod, which I believe has an output voltage of about 1V RMS and secondly, my M-Audio 2496 Audiophile sound card, which seems to have an output of 2V RMS, but this I shall measure myself to check.

With a desired input into the amp of 4V P2P, This edited diagram explains what I've done best:

Click the image to open in full size.

Unfortunately, I'm not sure what effect this has on the input impedance of the amp, or exactly (and this bit is crucial) where the attenuator goes , probably between the input cap and the source selector.

Thanks for the post!
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Old 2nd April 2007, 06:12 PM   #4
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Any thoughts on Nichicon Muse KZ's?

I've just about got all the SMT doodads mounted on my amp4 and should start thinking about upgrading some of the other bits. I'd like to know how things go for you. Good luck!
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Old 2nd April 2007, 11:01 PM   #5
xenob is offline xenob  Austria
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Hi

If you want to uprade the eletrolytics, you could also think of useing bypass caps of foil type. (see many posts on snubbers eg.)

My AMP4 is finnaly working beautifully and I think I prefer it over the AMP6.

I did not do much changes exept the input caps were replaced for Mundorf 2,2 ¬ĶF Polypropylene caps.

Click the image to open in full size.

Here you see my first experimental case.

Finnaly the amp went into a nice fisher aluminium case together with a dantimax relay stepped attenuator

Click the image to open in full size.
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Old 3rd April 2007, 10:56 AM   #6
v-bro is offline v-bro  Netherlands
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About Tripath amps driving capacitive loads, I drive electrostatic speakers with AMP9, but I've read about people driving fullrange ESLs with AMP5.....
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Max. cone displacement can be several foot on any speaker!Too bad it can be done only once......
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Old 3rd April 2007, 11:00 AM   #7
v-bro is offline v-bro  Netherlands
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here:
http://www.41hz.com/Forums/topic.asp?TOPIC_ID=492
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File Type: jpg ob-57.jpg (52.6 KB, 314 views)
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Old 3rd April 2007, 11:09 AM   #8
Peteruk is offline Peteruk  United Kingdom
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Quote:
Originally posted by whitelabrat
Any thoughts on Nichicon Muse KZ's?

I've just about got all the SMT doodads mounted on my amp4 and should start thinking about upgrading some of the other bits. I'd like to know how things go for you. Good luck!

I also posted this thread on Audiocircle here, and after discussion on there, concluded that the Panasonic FMs were the most suited to most places. More info can be found there .
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Old 3rd April 2007, 11:19 AM   #9
Peteruk is offline Peteruk  United Kingdom
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Quote:
Originally posted by v-bro
About Tripath amps driving capacitive loads, I drive electrostatic speakers with AMP9, but I've read about people driving fullrange ESLs with AMP5.....

Hey V-bro,

That's good to hear. If I do have the effort to build a Cat5e project then, it should work fine .

I'm Reverie off the 41hz forum by the way .
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Old 3rd April 2007, 05:26 PM   #10
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I've ordered a set of Nichicon KZ's with values 1x 10uF 10v , 1x 1000uF 10v, 2x 330uF 35V. Voltages may vary though. I was buying some for a phono amp and figured, why not. I'm not sure how to compare these to the Panasonic FM's. I looked over the specs for both. I guess only time will tell.
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