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Old 5th April 2012, 09:09 AM   #1
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Default Comments on chipamps vs. class-D (Ucd & LM3886)

Hi there,

I’d like to share some listening experience with my freshly assembled Chipamp, wich sings now since three days.
Although it is not enough to have any definitive comments, it played constantly, sometimes in low level but also by listening with me in front of the speakers.
I bought this kit from Brian Bell in 2007, and now exactly 5 years later it’s finally playing… don’t ask me why it took so long but there is a story behind.
I’m an addicted to Hypex’ class-D amps since 2005, when Bruno, who was a colleague of mine at Philips at that time, lent me his prototype for a couple of days. The day after my ICEPower 500 modules where on eBay, and I ordered a set of UcD400 in the Netherlands.
In 2007, curious if a “normal” class AB design could do better, I got my chipamp kit but did not have time to build it. End of 2007 I upgraded to UcD400HG, equipped with HxR regulators, the original PSU’s and trannies from Hypex; a friend made me a nice casework – now I was in heaven – a reason why the motivation to assemble the chipamp was not around.
In 2011, Holger Stein, from Steinmusic in Germany gave me a set of his MicroTube and MicroPower kits, which are respectively a very simple tube preamplifier with AEG 5702 WB microtubes; the power amp uses a small stereo chipamp on a single PCB. The chip appears to be the TDA8560 or TDA8563Q, it is designed for a use in car stereo devices, but run with +18 volts it makes about 2 x 40 watts on two ohms. It needs only a few external components, including 470nF input coupling caps, which I replaced with MKP1837 devices.
I plan to build an integrated stereo amplifier, as the MicroTube has an unusual output impedance of some 2200k ohms, so I don’t want to use it as a stand alone preamplifier (as Stein suggests it).
Anyway, it was a “zero Euro” concept: I didn’t want to spent any money on it since the kits were a gift (I know Holger since more than 15years…), I had a nice existing case made by myself for another project 10 years ago which I repainted (expenses here: 15€…), and I still had some motor driven potentiometers, and IR control, knobs, sockets etc.
The amp is almost finished but I first wanted to try it as a power amp first, and connected it instead of my UcD400 power amp.
Surprise: in term of musicality, it beats the UcD amps… (sorry Jan-Peter). Let’s say it in a different way: despite its sophisticated technology, the UcD amp sound like an amplifying wire – very neutral. Tuning a speaker with it is the best thing to do as it is so neutral, that the speaker will sound on any amp.
On my speakers, who sound slightly laid back, and lack a tip of warmth in the low midrange region, well the UcD sound to same. It is despite its exactness, transparency, image and dynamics a little unemotional.
The MicroPower amp is not 100% neutral, it doesn’t have the power at the bottom end, neither the depth in the image, but it lights out the midrange almost as a tube amp, highs are sweet and smooth, and voices palpable.
Intrigues what a 10$ chip could do, I dig out my chipamp kit; a couple of industrial transformers of about 350VA with 4x24 volts in series have been reconnected to get 2x24 volts, an old HiFi2000 case got a new nice gold anodised alu frontplate that I’ve got from the same supplier then Atoll, here again I didn’t spend a dime taken in condideration that every was paid since years.
After some weeks of assembly the dy came when it was working, and after a half hour of warming up I plaid a couple a songs. The spark didn’t come over yet, there was something but the bass was full and not controlled, highs were brilliant and forward, yet the image depth definitively better than the MicroPower (thanks to a real dual mono PSU).
The my seven years old daughter decide to watch Alvin and Chipmunks in the neighbour TV room, which meant end of listening session so I let it run with low level music all night.
Next day in the morning: quick listening – and – yeah it’s better but not to yell eureka.
I replaced the input resistor of 1k by a Dale type, ad a ferrite on the mains cable within the case, and a small filter (C + toroidal core inductor +C), and let the beast play until night.
So, there I spent until 1AM to go through my best vinyls, but also – for a change – digitally stored music (Squeezebox with an external Arcam rDac).
On my hard-disk I have an umpsampled version of Niels Lofgren’s Live CD (upsampled to 24/96 with dBPoweramp, and yes, it does improve the sound).
Well, I never heard this album like that, I took the time to listen from first to last track and it was revealing. The LM3886 is definitively a killer. Better than the TDA amp? Yes, because the TDA truncates a little the low end. I have to add that the TDA amp came with a switching PSU, I’ll will replace it with a linear one later, might improve the sound.
The LM3886 is also warmer in the low midrange, there where I needed it. The LM is still a little bit brighter but after two days of burning in it’s well integrated. 3D stage is astonishing – I always thought it was the domain of class-D amps, but the dual-mono LM3886 does is just as fine.

I'll post some pics of the amps.

Cheers,
- daniel
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Old 5th April 2012, 09:27 AM   #2
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Default Comments on chipamps vs. class-D (Ucd & LM3886)

Here some pics of the amps.

The UcD amp is the one with the curved fron, the LM the one with the alu front ond a urve in it (slightly golden), the integrated amp using the TDA chip is the Yellow and red one
Attached Images
File Type: jpg UcDAmp_front.jpg (143.3 KB, 492 views)
File Type: jpg UcDAmp_back.jpg (109.7 KB, 482 views)
File Type: jpg LM_AMP_front.jpg (118.5 KB, 474 views)
File Type: jpg LM_AMP_back.jpg (125.4 KB, 467 views)
File Type: jpg MicroTube_Power_front.jpg (134.7 KB, 461 views)
File Type: jpg MicroTube_Power_back.jpg (123.0 KB, 89 views)
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Old 5th April 2012, 09:39 AM   #3
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thanks for the good story and those amps look fabulous

my experiences with IC amps are a simple gainclone, heavily modded topping td20 and myrefc. of course myrefc blows everything else i heard in the past out of the water but the t amp has a certain charm that's hard to put down.

i'd say t-amp is 'mosfetty' in a fit of my silly vocab.
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Old 5th April 2012, 10:29 AM   #4
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I have build active speakers with UcD modules and with LM3886 chipamps. There is really no comparison, the UcD blows the chipamps out of the water in terms of neutrality, dynamics, distorsion and so on. If you like the sound of a chipamp you probably like a bit of distortion with your music. Nothing wrong with that but maybe you want to look at a more controlled way of introducing distortion, maybe a nice tube buffer that produces even harmonics in combination with UcD amps will be a good match for you? Best of both worlds so to say..

Just my 2C!
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Old 5th April 2012, 11:36 AM   #5
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Quote:
Originally Posted by Mark.Clappers View Post
maybe a nice tube buffer that produces even harmonics in combination with UcD amps will be a good match for you? Best of both worlds so to say..

Just my 2C!
i´b been thinking of doing just that , a ucd amp with a tube buffer/preamp
bet it will sound nice
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Old 6th April 2012, 08:06 AM   #6
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Default Comments on chipamps vs. class-D (Ucd & LM3886)

Quote:
Originally Posted by PreSapian View Post
my experiences with IC amps are a simple gainclone, heavily modded topping td20 and myrefc. of course myrefc blows everything else i heard in the past out of the water but the t amp has a certain charm that's hard to put down.
I checked, and the myreffc looks interesting. Maybe later I'll try, but on my wish list there is an amp with 2 or 3 chips in parallel.
But just right now I'm happy with my "simple" amp.

I used to have some T-Amps in the past. Sound was somewhat smooth, and I preferred the UcD sound.
Still have an eval board with the 2020 somewhere, need to hook it up.

- cheers, Daniel
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Old 6th April 2012, 08:15 AM   #7
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Default Comments on chipamps vs. class-D (Ucd & LM3886)

Quote:
Originally Posted by Mark.Clappers View Post
... Nothing wrong with that but maybe you want to look at a more controlled way of introducing distortion, maybe a nice tube buffer that produces even harmonics in combination with UcD amps will be a good match for you? Best of both worlds so to say..

Just my 2C!
Mark, I didn't say the UcD was a bad amp, far from that. I had it for almost 7 years now, and I will not sell it. I'll move in Summer, and new home means new speakers, and maybe the UcD will be more suitable again.

As I'm on a permanent "construction site" ("bouwplaats") with my tube preamp, a 6N3 SRPP, rather simple but excellent in sound, I'm use to combine it with some UcD amp.
When I hooked it up with the UcD, it was a dream combo. Still not finished yet, and in meantime I'm listening with a MM-Audio "MiniPre", which is also an Bruno's design, using a LM4562 OpAmp in a pure balanced design. MM-Audio belongs to Hypex, but they don't make big sales with it I guess.
I modified mine, by replacing the standard 7812/7912 with the Hypex regulators, nice improvement. It's a good preamp, but my Tube preamp is better and more involving.

When it's done I'll post some impressions.

- cheers, Daniel
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Old 6th April 2012, 08:17 AM   #8
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Quote:
Originally Posted by lduarte1973 View Post
i´b been thinking of doing just that , a ucd amp with a tube buffer/preamp
bet it will sound nice
See my post with the tube preamp: definitively the right way to go.

- cheers, Daniel
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Old 6th April 2012, 09:48 AM   #9
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Alfetta87, Please check out this thread, The RR is a great addition to the BrianGT amps.

http://www.diyaudio.com/forums/chip-...ml#post2924833
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Old 6th April 2012, 11:14 AM   #10
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Hi Bob,

I saw this thread already, and it sounds interesting to me. Didn't know this technology (thanks to diyaudio.com we learn new stuff all the time).

Since I just replaced the 1k R's with Dale types, I'll stick around with them 'till I get bored - then I'll try those LDR items. Will let know the community about the results.

- cheers, Daniel
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