Building my Amp11's (Was: Amp11 or Amp4)

[reine73]

Hello

I am quite new here, and new to audio stuff, but not really to electronics in general (usually stays at the digital side).
I have been reading a lot of posts and have tried to sort out some answers to my questions from that.

I did choose the Amp11 forum for these questions as I lean towards the Amp11 now, but that might change from the answers here

I have read that Amp4/Amp11 a little better from an audio perspective when compared to the other kits (except for the truepath)
and I am therefore aiming at one those two (ok, in case of the Amp11 it would be two of them, obviously ).

As stated here the Amp4 is better suited for 8 Ohm loads, and the Amp11 is better suited for 4 Ohm loads.

• The Amp4 is at 50w@8 Ohms and amp11 is at 100w@4 Ohms, so would I end up with 50w if I connect the Amp11 to 8 ohms? This would mean that Amp11 is basically a "high current version" of the Amp4, is that correct? (ok, optimized for mono... so less omponents)
• My speakers are specked at 4-8 Ohms (Dynavoice challenger S5), which I guess depends on the frequency, would that imply that I am better off with the Amp11?
• I have read that other input caps are recommended, but it is quite hard to grasp what to choose, are there any of those others available here at the shop as well? any recommendations?

Now to a very subjective question, that is hard to answer I guess, unless you have first hand experience...
Today I have a Sonic Impact T-Amp, the flat generation 2 version of it which is using the 2024 chip set. The speakers (Dynavoice challenger S5)
which are quite small but ok (and I won't get anything bigger according to my significant other either, or my wallet for that matter)

Today I get the feeling that it doesn't quite cope when raising the volume a bit, not really that high...

Will I notice a big difference with the amp4 or dual amp11?

Will I notice a difference in audio quality as well?

Btw. I have had a very good time reading this forum, keep up the spirit here! love it!

Best regards
Reine

[V-bro]

Hi Reine and very welcome!

There are STA517B chips in stock now at 41hz, I could help you out on building a high current high voltage AMP4! This can be VERY exciting pioneering, but if you just want something that is more thoroughly tested then I'd go with an AMP11. The sound of all the TK2050 amps I render better (by a very small margin though) than all the other Tripath amps (including the TA3020 amps like Truepath!) The thing is, Tripath have pulled out another trick from their sleeve to keep the distortion and noise level incredibly low in this chipset. Unlike all the other chips. Still the sound of all these amps is quite comparable and all at an insanely high level, so you will probably be more than satisfied with any of these amps with a little more power than the TA2024 based SI amp. The SI amp is overall built from much poorer components than all the 41hz kits, so there may be a problem with the distortion you have. Also the power supply you are using could be much the cause of this...

The high current AMP4 would be well suitable to drive 4 ohm loads up to more than 30Vdc, probably even 40Vdc! The difference is 40V max and 3A against 60V max and 6A power stage. Do keep in mind that the 'modification' includes replacing all the 100nF caps for X7R quality (still cheap) then most of the electrolytic caps have to be changed and you need to externally feed the 5V regulator circuit (or use PS4, which can easily take the higher voltage) Plus the relay needs a different value resistor to adapt it to the higher voltage. And if you want to go brutal you might better use AMP9 wire on the output inductor cores (which you wind yourself anyway)...

I'm sure 41hz can help out with the parts, just order an AMP4, use "pay by bank" which basically puts the order on hold, then open up a support thread to ask for the right components.

I shall make an AMP4-HV BOM if necessary...

[krilli]

• The Amp4 is at 50w@8 Ohms and amp11 is at 100w@4 Ohms, so would I end up with 50w if I connect the Amp11 to 8 ohms? This would mean that Amp11 is basically a "high current version" of the Amp4, is that correct? (ok, optimized for mono... so less omponents)

Precisely!

• My speakers are specked at 4-8 Ohms (Dynavoice challenger S5), which I guess depends on the frequency, would that imply that I am better off with the Amp11?

Yep. The parts of the spectrum where the speakers are 4 Ohm COULD kill an Amp4 running at high volume, high voltage. Probably it would be OK though - forum people have ran the Amp4 at 24V into 4 Ohm successfully. But that's details. Your understanding is correct, and 4 Ohms does indicate an Amp11.

• I have read that other input caps are recommended, but it is quite hard to grasp what to choose, are there any of those others available here at the shop as well? any recommendations?

I've thought a lot about this ... and it doesn't really matter In my opinion. There are pretty good film caps included with the Amp4, and you can fit almost any cap to the Amp11, and you can always swap and test later. I have tried different caps, biiiig Obbligato film caps and nice box polypropylenes from 41Hz and Wima PPS caps and electrolytics and ... well, I haven't heard a clear difference between any of them. I have these in my Amp11: http://shop.41hz.com/shop/item.asp?itemid=883&catid= ... search for "MKP" to find other metallized polypropylene at the 41Hz shop. Cheap and cheerful, and the sound from the system is very very good. Polypropylene is said to be one of the best sounding types.

I mean I'm sure it matters to have good caps, but there are so many other factors that are more important, for instance what amp you choose, how you power it, how you connect the system together, how far from the walls the speaker are ... The most important one is that the amp gets built. I am talking like this because I spent a long time overanalysing input caps, myself, and I'd hate to have to wait for your amp-building success story

Now to a very subjective question, that is hard to answer I guess, unless you have first hand experience...
Today I have a Sonic Impact T-Amp, the flat generation 2 version of it which is using the 2024 chip set. The speakers (Dynavoice challenger S5)
which are quite small but ok (and I won't get anything bigger according to my significant other either, or my wallet for that matter)

Today I get the feeling that it doesn't quite cope when raising the volume a bit, not really that high...

Will I notice a big difference with the amp4 or dual amp11?

Will I notice a difference in audio quality as well?

I think you will indeed notice a difference. I looked at the specs for the speakers and saw they have 89dB/W efficiency. That's OK but low-ish for an amp running at around 12V, like the TA2024. I have some 90dB/W Mission speakers at the office, and really start to shine at around 30W, which is what I get out of my Amp11's at around 20V rail voltage. You'd probably be very happy at a supply around 24V.

With those speakers, I'd say you can choose either Amp11 or Amp4. You'd be hard pressed to burn an Amp4 powering these.

4 and 11 are VERY similar. There are some small differences: The Amp11 has a very interesting dynamic character, especially in the bass. Stuff like Boards of Canada and parts of the Blade Runner soundtrack for instance are ri-diculously dynamic through this amp - quite amazing. Conversely, the Amp4 has this extra sweet and magical midrange. Incredibly captivating and musical.

But make no mistake, Amp4 is very dynamic. And the Amp11 has a very sweet midrange of course too ... The difference between them is IMO less than the difference between them and the TA2024. My personal fave is the Amp4, but the Amp11 is growing quickly on me.

W.r.t. practical matters:

The Amp11 looks cooler and is more flexible because you can use a broader range of speakers with it - 'cause it handles 4 Ohm and a little below that.

The Amp4 is cheaper all in all for two channels (i think), and has a speaker protection relay, and is a bit smaller than a couple Amp11's.

I hope I haven't talked too much I'm evaluating what amps to build next, so I'm giving the Amp4 / Amp11 choice some thought these days.

[Scratchy]

Have you seen this thread with the very useful comparison chart?
http://www.41hz.com/forums/showthrea...z-AMP-PS-Chart

As Krilli mentioned, the AMP11 has no speaker protection relay or power supply, as compared to the AMP4.
You should have very good soldering skillz if you plan on building one of these SMD amps.

[kifysara]

If there is a consensus amongst the most experienced of you guys that the TK2050 amps are the best SQ-wise then perhaps we should ask Jan for an "ultimate" AMP12 or something?

[AMP12 = High power AMP11-type mono amp which combines all the good stuff the 4 and the 11 have and then some (see: relays, good onboard PSUs etc. etc.) !]

I'm sure it'd turn the heads of the Sure crowd and many more..

[reine73]

Wow, thanks all of you for you answers, awesome!


V-Bro:

That do sound like a bit overwork for me for the moment, for me the actual build of the standard AMP4/11 would be a very exciting pioneering for me personally at the moment . This is my first kit build and my first smd soldering.
The things I have been doing earlier is basically my own designs or modifications or plain ripoff from other persons designs, and as I mentioned, mainly digital stuff...

But I do actually have one ongoing project now, a modified CMoy, six channel for my surround headphones as I think that they do have some impact on the surround speakers to my computer if they are just splitted from the line-out. The main modification is that it has a differential input to lift signal ground to a virtual ground as it is going to be powered by USB (I had very bad result when connecting the signal ground to ground...)
So as this is my first smd project I have thought a while about it before posting here and finally thought after

watching some smd soldering on youtube "Well, I can do that... ".

So I do think I will stick to the standard kits. But thank you very much for the offer of creating a bom-list!


Krilli:

Nope, that was not a to long answer, that was actually a great answer as it actually answered a lot more questions then I had asked!

I will probably go with your input cap suggestion as that seems like a good choice, and not to exotic to be expensive...


Scratchy:

Yes, I know I need quite good soldering skills for this. I have thought about it for a while and I do think that I will manage... after looking at quite a few examples of how you can do this I do have enough confidence that I will cope with it, but it will be a challenge...

At least, I do have a quite ok temp controlled soldering station at about 50W



After reading the answers here and been thinking for a while about it, if this work out good, I will probably not build another one in reasonable time (have you heard that one before? ) So I would like it to give me a wide choice of speakers in the case that I actually get better ones sometime, so I guess I will end up with something like this:

• Amp11 x2 -(to be on the safe side today, and also be able to drive 4 Ohm in the future)
• PS1 -Good, because I don't need to design the power part myself, and it also adds speaker protection
• 2x20V 220VA toroid transformer, will give me around 28v
• Input capacitors suggested by Krilli

Then the 80 mm high galaxy box would enable me to put the amps on the sides, giving them the thick aluminum sides for cooling (with ground isolation).

And of course, some digital control logic for power, power on mute and that stuff

Does this sound good to you? something obvious that I missed out? (ok, I didn't mention switches, fuses and that kind of stuff)

How badly do I need shielding for the transformers? ( I need two of them, as I plan to have one constantly running to power the digital logic)

And thanks all of you for spending the time to give me those great answers to my questions!
Best regards
Reine

[V-bro]

The Sure crowd are bargain hunters, care more for the price than quality. Not to say the product sucks, but it sure isn't very good either. Here at 41hz you buy much more serious quality stuff, and that attracts a different crowd anyway. We all know that it doesn't just take the board to get it done. When you take the trouble to make a complete amp and add the price of a power supply and a nice case and sockets and stuff the amp better be great, not just mediocre. Plus it's much more fun and educative to build it yourself all the way from the board and components.

There will be new TK2050 designs I tell you! I've got some pans on the stove myself!

I am also very curious to how a the TDA2500 amp will eventually perform! It may be just as good as the other TC2000/2001/2002 based amps, but then much more powerful. It might be that using fet drivers with it and large fets makes it perform the same as the other amps with external fets. But I think it will not, it WILL be better because of the tricks in the TC2001 that influence the distortion behaviour so positively in the high frequencies.

[Scratchy]

Hi Reine and very welcome!

There are STA517B chips in stock now at 41hz,

http://shop.41hz.com/shop/search.asp

Search Criteria: 'STA517B'
Records/Items Found: 0

Help, I can't find them!

[V-bro]

As you can see the AMP11-HV is back in stock, but the chip may not have been placed on the site. I'm sure Jan will respond when you open up a support thread.

[krilli]

• Amp11 x2 -(to be on the safe side today, and also be able to drive 4 Ohm in the future)
• PS1 -Good, because I don't need to design the power part myself, and it also adds speaker protection
• 2x20V 220VA toroid transformer, will give me around 28v
• Input capacitors suggested by Krilli

Then the 80 mm high galaxy box would enable me to put the amps on the sides, giving them the thick aluminum sides for cooling (with ground isolation).

And of course, some digital control logic for power, power on mute and that stuff

Does this sound good to you? something obvious that I missed out? (ok, I didn't mention switches, fuses and that kind of stuff)

Sounds pretty good to me! Rather awesome actually.

One thing that sticks out ... I don't 100% understand how the two transformers feed the PS1 and the Amp11's and the digital logic. I'm very sure that it's going to work, I don't doubt that, I just can't picture it completely