Altering an AMP4 Kit - PIO Caps, Coils, Attenuators and SLA Batts.

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Reverie

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After having a Sonic T amp for a fair few months, and being very impressed with its performance, I looked into making myself another ‘class t’ amp. Coincidentally, my T-amp seemed to develop an irreparable fault. After only a minute or two of standard use there would be a huge noise build up through one of the channels until it reached an unbearable level; the chip got very hot too, but cooling it seemed to make little difference.

Anyway, I’ve recently bought an amp4 kit from www.41hz.com,. I've been looking over the spec, looking at other TK2050 amps, and listening to other people's ideas as to how you can 'upgrade' this kit, without wasting money.  As will become very obvious by the end of this thread, after reading the 6moon's review of the Red Wine Audio Signature 30 , I’m aiming to try and replicate that amp’s performance as much as my budget will allow. It uses essentially the same tripath chip.

There are a few areas I’ve been considering:

Coils
I’ve got a clear choice between toriodial or air core:
Air core – Many DIY people I’ve spoken to have said they believe these to have ‘a smoother operation.’ I’ve been pointed in the direction of these from autocostruire.
Toroidal – These are what come as standard with the 41hz kit and also supposedly what Vinnie uses in the Signature 30. According to him  these are ‘favored over air-core inductors for better bass definition, speed, dynamics, and lower noise’. However, I haven’t looked out of ferrite cores to other cores, such as MPP.

Capactiors (input filter)
It seems the general opinion is that paper in oil capacitors are the way to go.  As for what value – the 41hz kit comes with 1uF and 3.3uF, but after discussions with Vinnie, he said he used a value of 2.2uF, which is a compromise between the two, so I think I shall follow suit. However, back to what type of capacitor:
Jenson:
Copper Foil 2.2uF 100V - $60.95 – Very pricey, but exactly what the Sig 30 uses.  Supposedly legendary.
Mundorf:
Silver in Oil 2.2uF 1000V - $43.90 – Not cheap, but considerably less than the Jensens. Some people who have made their own amps have expressed the view that they think that these are in fact better than the fabled Jensons.
The M-CAP Supreme 2.2uF 800V- $21.90 – Much better value, but in a totally different league. The reason I’ve included these in my list is that some listening tests argued that there was no real noticeable difference between the higher tier of the Mundorf capacitors.  This thread here: http://www.diyaudio.com/forums/showthread/t-50254.html gave a range of opinions on them.

I’m not entirely sure how important the voltage of the capacitor is. Surely 100V is plenty for this application?

Attenuator
For volume control. The signature 30 uses the DACT 2. However, this is very expensive, so I’m looking for suggestions for much cheaper alternatives.

SLA Batteries
As I loved the portability of the Sonic T, I’m going to try and run the amp off batteries too. However, as this will probably be the last part of the making, I haven’t given this much thought yet. Is there anything I should consider?

All suggestions/comments very welcome!  :D
Peter.
« Last Edit: 26 Oct 2006, 03:46 pm by Reverie »

Jampot

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Some more reading on caps here -

http://www.humblehomemadehifi.com/Cap.html

I don't doubt you will finish up with a fine amp.

Good luck

Jim

ebag4

Peter:
I have ordered an Amp 4 as well and look forward to any responses you recieve from this thread.  With regard to the input capacitors, I was able to purchase the Jensens from Ebay for approx $35 (from rex_imp).  I have been running these in my self modded T-amp for a couple hundred hours now and they are sounding good.  i will be trying these with my Amp 4.  I have also decided to try the Promitheus TVC for the volume control duties, I am anxious to hear this combination.

Best,
Ed

GHM

I wish I could be of more help. I have a unit similar to yours in the works. I'm having mine put together by a friend whose been busy lately. He informed me the unit wouldn't be complete till December. So I haven't heard it at all. I can't complain..he's building it for free! Also you may want to ask Michael Mardis about this. He uses the Obbligato Premium Oil Capacitors in his commercial T amp. He told me they sound terrific and not overly expensive either. Since the addition of my Promitheus..I've considered asking him to make me a direct connection for separate volume control.

Mine has the 41Hz Tripath TA2022 chip. You may consider the Endler stepped attenuators also in place of the DACT..much cheaper.

This is what my unit has in it right now.

Endler 4k ohm 24 stepped stereo attenuator
12 SLA 12 volt batteries as a power supply
Vampire gold plated solid copper RCA inputs
Eichmann Cable Pod Gold plated binding post
Silver over copper signal path wire from e-ticket cables
Mundorf Supreme Silver PPIO input coupling caps 2.2uF
Custom built Maple stained wood chassis

Reverie

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Thanks for the replies people, I've been looking into what you've said...

http://www.humblehomemadehifi.com/Cap.html

Excellent source on caps, pity it doesn’t feature the Jensens.

Quote from: ebag4

I was able to purchase the Jensens from Ebay for approx $35 (from rex_imp)
I had also seen his caps on ebay, and asked him for a price on that value and got the same inexplicably low price  :?. I hate to be suspicious, but are they genuine? I've emailed for confirmation. 

If it's true, then I can't really go wrong with them from him at that price  :green:.

I’m very interested to hear the results!

Quote from: GHM

I have a unit similar to yours in the works...

Seems you’re in a very similar situation too. It’s interesting to see you’re using the Mundorf Silvers – I was split over them and the Jensens before I saw the cheap supplier.
 
Also, that attenuator sounds impressive for the money according to the review on the site, but they are only single channel devices :( . Will I notice much difference using a potentiometer, something like an ALPS perhaps? Though I could go higher than that price.

I'll probably refer to your list when it comes to the later stages of development  :D. Interesting that you use special signal path wire.

Where did you get your SLA batts from may I ask? And 12? That's quite a few... :scratch:

GHM




Seems you’re in a very similar situation too. It’s interesting to see you’re using the Mundorf Silvers – I was split over them and the Jensens before I saw the cheap supplier.
 
Also, that attenuator sounds impressive for the money according to the review on the site, but they are only single channel devices :( . Will I notice much difference using a potentiometer, something like an ALPS perhaps? Though I could go higher than that price.

I'll probably refer to your list when it comes to the later stages of development  :D. Interesting that you use special signal path wire.

Where did you get your SLA batts from may I ask? And 12? That's quite a few... :scratch:







Hi Reverie..actually I have the stereo version attenuator. Go to the bottom of Scott Endlers main page you'll see them. Here's one place to buy the batteries Battery Mart. I ended up with so many batteries from several incomplete projects. So instead of just letting them sit unused. I decided to put them all in this integrated. The chassis is pretty big. There's room for more.. :lol:

shep

check this out. Also Panasonic makes a very nice pot.
http://www.diyfidelity.com.au/product_info.php?cPath=0_33&products_id=32
I'm going a similar road, having mine made though. I haven't a clue how it will sound!

Reverie

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I’ve had that kit recommended to me several times now, looks good.  :)

Any more comments on MPP or (as has been recently suggested to me) ‘amorphous’ cores (these could be very similar terms for non-ferite, I’m not sure)? A recent link given to me was:
http://www.metglas.com/

For the record I need a value of 15uH.

GHM, what input voltage is best for the amp 4? And how are you supplying that from the batteries?

I've seen a few Endler attenuators like yours in kit form that look promising. Isn't your 4k value a bit low though? It recommends 50k in the guide...

Thanks.
« Last Edit: 14 Nov 2006, 10:53 pm by Reverie »

Reverie

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My appologies people, I just noticed I had a totally unrelated link pasted in my previous post.  :oops:

It has now been alterred to the correct one.
« Last Edit: 17 Dec 2006, 02:55 pm by Reverie »

GHM

Sorry for the late reply Reverie. I talk to my friend about this but I can't remember exactly what he said about the power supply voltage. I think he's using a 5 volt regulator? Not sure on this though.

From talking to Scott Endler..he suggested I try the 4K ohm attenuator. Not sure how well it will work though. I've read it must be at least 10k ohms or lower.. so hopefully 4K ohms won't be a big deal.

Reverie

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Thanks.

I'll ask around about the attenuator size, as I'm sure the amp4 PDF says '50kohm'  :scratch:.

Something that did catch my attention quite urgently though - I haven't even begun to consider what to do about the output capacitors. On the tripath datasheet they emphasise the recomendation of 'high quality film caps', on Co and Cz capacitors  :|.

Is it worth throwing so much money at these ones?
Do I have the same range of caps I can use for these as I looked at for the input, or are specific sorts needed?
The Jensons again?
Your usage?

Excuse the barrage of questions, but any advice would be appreciated as always. :D