Chip Amp or what Amp?

[pappaapa]

OK! I didn't mean this to turn out an autobiografy, but it seems it did. For those of you who don't have all the the time in the world, as I seem to have, I've tried to highlight the most important parts and you can skip right to the questions.


Hello everybody!

Let me begin with saying that I've never in my entire internet life, before this, have stumbled across such a gathering of good hearted and as it seems pedagogically talanted people.
Cudos!

My name is Levi and I'm from Sweden. I just recently got bitten by the HiFi-bug. I've always had the DIY-bug crawling around in my pants, just never when it comes to electronics. Also I've always been a passionate music lover (and creator). But not until three or four of years ago, when a friend invited me in to listen to his +10,000 euro (15,000 $) Hi-Fi rig I got the audiophile-bug. After that my favorite records just didn't sound the same anymore. At home I still had the same stereo I bought for my first real pay check (I'm guessing -92 -93 -ish) and a pair of Celestion speakers from the sixties, that I robbed my mother of when I left home.
What the pay check got me was a NAD-302 amp, a Denon DCD-595 CD-player and a Denon cassette deck now hiding somewhere under a stack of books in the shelf. Actually the 33-year old me is rather proud of the 16-year old me. I could just as easilly have ended up with a peice of plastic.

Ok, so I got the bug!
The problem is, ever since, I've been a poor architecture student and oh my lord this stuff is expensive. I managed to come around a pair of speakers (JPW Ruby II), they cost me ca 100 euro (150 $). For those of you who don't know these speakers,and most people don't, they were manufactured around the year 2000 and they sound a hell of a lot better than my mothers old Celestions. But they are not the most sensetive of speakers (rated at 88 dB and 6 ohm) so when I plugged them in to my old NAD 302 (rated at 25 watt and switchable between 4 and 8 ohms) it sounded like Leaonard Cohens bass-player had trouble at home, he definitely forgot to take his mittens of before recording. There was just no way for the NAD to give the speakers what they needed. Luckily I came across a pair of Rotel RB-850's (2*50 or 100 bridged watts, 8 ohm impedance) for what I could afford, 100 euros for the pair. I plugged one of them in, using the NAD as a pre, and the bass player got his mittens off but was still thinking about his wife at home, cause the timing was still awful. I plugged the other one in (briged mono) and it happened. I spent hours and hours, running through every record I had.

All good and well you might think!

Just a couple of days ago I got my first DIY audio project, a shigaclone, up and running and it's amazing how the good stuff can make you notice the bad stuff. The treble sounded like never before, at least never in my appartment, but that was it. Nothing happened to the rest. So now I have very clear and separated high frequencies but a very unbalanced soundscape since the lower freqs are the same as before.
Today I've been fiddeling around with different setups. Listening to just the NAD, the NAD and one Rotel, the NAD and two Rotels, and with the signal straight to the Rotels.
-I found that the NAD brings the treble. With only the Rotels there's no separation and no edge to the sound.
-The Rotels brings the prescence to the bassline (the fingers on the strings).
-Together they match up pretty well, but I will never get satisfied with them since nothing of anything truly gets expressed.
-I need new amplification.

So I'm new at HiFi, I'm poor, and as some of you might already have figured out, I'm an absolute beginner at electronics. But I'm still gonna build myself an amp.
As it turned out, building the shigaclone, I was pretty good at soldering so that's not going to be a big problem.

Here are the questions:

1 - Concidering the pile of bills lying here next to me I really would love to go for a chip amp.
Concidering my speakers, is a chip amp what I should be looking at?

1.1 - From what I've been reading here on the board, the LM3886 is the best chip amp for me. True, false?

1.2 - What schematics should I be looking at, whatever chip amp recomended? Peter Daniel's and BrianGT's or National's or what's out there? (I plan to do a p2p)

1.3 - If I build a chip amp I've been meaning to scavenge the trafos from one of my Rotels. I measure them at 28V so they would probably work but they're not torroids ( I don't know what you call them, El, laminated???). They look really sturdy and nicely built but what I've read is that they are much noisier than torroids. Is that going to dissapoint me in the end?

2. If a Chip amp turns out not to be for me (i.e. my speakers) what is the "next best bang for the buck"?

3. It seems to me we're short on audio grade caps here in Sweden. We've got Rubicon YXF an Sanyo MV-AX series. Any ideas on them or where to shop?


-Thank you for listening!
Or as we say in Sweden:
-Sorry for taking your time!
-Kara halsningar!

Levi

[pappaapa]

The stuff I tried to highlight almost disappeared. Can't seem to find the edit button. Just mark the yellow text with your cursor and it will be readable. So sorry!

Levi

[dantwomey]

Just recently I tried one of Peter Daniel's chip amp kits and I couldn't be more pleased. Results and support are second to none.

Regards,
Dan

[pappaapa]

Originally Posted by dantwomey

Just recently I tried one of Peter Daniel's chip amp kits and I couldn't be more pleased. Results and support are second to none.

Regards,
Dan

Yeah! I think I must have read thousands of his posts at this forum and just about everything that is to read on the audiosector webpage. And I've heard nothing but good things about doing buisiness with him.
I'm just not sure if the lm3875 and the lm4760 are right for me. (I would love it if the 3875 was an option with my speakers)

What chip did you go for and what speakers do you have.

And anyone; is making a p2p amp too hard for a noob like me? I can afford the kits. Just have to save a little longer.

Regards
Levi

[Minion]

Accept a 2 x 28 transformer is going to be a bit high on the voltage side for a LM3886 , at 2 x 28v you will get close to +/-42vDC which is the very max the chip can tollerate and would need a very Large heatsink and if the voltage were you live fluctuates up and down you risk going over the Safe voltage limit ....

the TDA7293 is good at 42v and are more powerfull and sound good accept they are a bit harder to use and the kits aren"t nearly as common as a LM3886 .....


good luck

[zebra100]

Hi,

I'm running an Audiosector LM3875 (premium) kit in dual mono. It is fed with 2x 18-0-18v, 120VA torroidal transformers and 1 rectifier board per amp module. I get about 24V off load at the rails. The attenuation is taken care of by a dual log Alps Blue attenuator (50k with a 47k metal film shunt resistor). This is mounted in a seperate box with 2 sets of inputs and a selector switch. The amp is used to drive Tannoy Mercury M1's (8 ohm nominal impedance).

It is a very fine amplifier. Excellent transparency, with good bass extension and a nice mid range. It cost me all in about £180 and I don't think it could be bettered commercially for less than £500. It might not win any beauty contests, but all I care about is how it sounds, and it sounds great.

Chris.

[pappaapa]

Thanks for the replies!

@Minion
I guess if I sell my Rotels I could buy a couple of good torroidals that are more in tune with the chip I decide upon.
I'm gonna have a look at the TDA7293 today. Thanks for the tip.

@zebra100
What's the average efficencie on your tannoy's. I did a quick search but didn't find it. I've too been thinking about building a attenuator with an input switch. Or maybee a B1 buffered pre.

[AndrewT]

Hi,
download the National datasheet and the application notes.
Read them thoroughly and implement all the option components, they are not really optional and omit them at your peril.

Build one channel of 3886 on a temporary support. No case, no hardware.
Listen to it and decide whether it meets your ambitions.

If you like what you hear, then build second channel and buy the remainder to case up your creation.

If you don't like the 3886 with your speaker then don't think that spending money on exotic components/cables will save the day. Junk the chipamp and keep the PSU and build something else from the reclaimed components.

[pappaapa]

Originally Posted by AndrewT

Build one channel of 3886 on a temporary support. No case, no hardware.
Listen to it and decide whether it meets your ambitions.

Hi Andrew!
That's very sensible advice and I guess it's the way to go. Although I'm eager to sit with the finished product and just enjoy.

Maybee I should get a couple've different chips and set up a test rig where it's not to much hassle to compare the different chips.

It sure will be much easier to enjoy, knowing you made the right choices.
The remaining chips can become mic preamps for my recording studio.

Levi

[zebra100]

Hi Levi,

My Tannoy's are 87db/w/m, Nominal 8 Ohm. They go loud enough for my needs and sound good with all types of music. They are great with classical, although they don't have the bass weight of a floor standing speaker. Very good with my chip amp.

My attenuator works very well in this application. I've never tried a buffer.

Chris.