6 channel amplifier considerations?

[Mackan2]

HI.
I'm thinking about building a 6 channel amplifier (5.1). What I want to achieve is HiFi-grade stereo sound and decent surround sound. I'm a rookie when it comes to amplifiers so I wanted to check in the forum if my assumptions are correct.

Will I achieve my goals by combining the following:
* 1 x Toroid transformer
* 1 x 41Hz AMP15-PS
* 2 x 41Hz AMP5

The AMP15 needs 60V and the AMP5 needs around 30. If I get a dual toroid transformer that outputs 30V, can I power all amplifiers by connection one AMP5 to each output and the AMP15 to both of them i series?
If this works, what kind of transformer do I need? 300VA? 500VA?

I think the front speakers I'm currently using are 8 ohms and the rest 4ohms but that might change soon :-).

I'm thinking about using one of the amplifier stages on the AMP5 to power a butt-kicker/bass-shaker (see first pic on http://minhembio.com/Mackan2/19901/ ) is this strong enough?

Is 1xAMP9 a better choice than 2xAMP5?

Thanks in advance!

[FFF]

It might be useful to give more info:

You want the amplifiers & power supply in one spot, or do you prefer to have (some of) them active?
Do you want really quality sound or just good sound?
How good are you with building these amp-kits? A lot contains SMT (very small components)

Why I ask?
Well, amp15 needs (max) 60Vdc Plus AND Minus NOT just 1x60Vac from that 'toroid'.
And amp5 needs (max) 30Vdc Plus AND Minus NOT just 1x30Vac from toroid.

A bit hard to go from 60Vdc to 30Vdc without serious losses. So you'll probably need 2 toroids.
And loading a toroid asymmetrically is not advised, unless for low power.

But if you want it simple you might want to use 2x AMP-9-basic, about 50W rms per channel.
Very easy to build, then a total of 8 channels (some spare, can be usefull), and only needs a single supply, say, 24Vdc.
But amp9-b can be a bit harsh in use.

You should read a bit about each amp, maybe the overview page in the TecDoc (top right), then left List-all-pages, AMP-ALL will give you some more usefull info and a picture of some.

And check on this thread: http://www.41hz.com/forums/showthread.php?699-6-channel-Home-Theater-Amp&highlight=5.1+surround

You might want to check out AMP-11 (mono) or AMP-10-basic?

[krilli]

Interesting idea w/ the transformer ... wish I could tell you if it's going to work

You probably know this but: The Amp15 doesn't need 60V, it can take up to +/- 60V. I believe it turns on at +/- 18V when correctly adjusted to do so.

Anyhow: Which amp and transformer to choose depends a lot on what speakers you have. Most important is the dB/W efficiency of the speakers, and the speakers' impedance is also somewhat important. Got those figures?

[Mackan2]

Thanks for fast replies!

Now I finally get what the +/- means, thanks. I guess that means 1 toroid / output voltage...

To answer your questions about my setup;

• I currently own a pair of B&W 602 s3, they are rated at 90dB/W and 4-8ohms. ("full" specs in swedish: http://www.prisjakt.nu/produkt.php?e=3394 ) But I'm going to get something else a bit more high-end in the future. I have been looking at Dali Ikon 5 (88dB/W and 8 ohms) http://dali-speakers.com/display_con...s.html/171/986
• The center and rear speakers are cheep shit to be honest, they work for me when watching movies (4 ohms). Maybe I'll get something nicer in the future (nicer as in less ugly).
• I will buy a high-end sound card for my TV-computer when I have a nice amp, I will use the sound cards volume, delay, balance, etc. and let the amp function as a power amp (is that the correct word?)

For starters I will probably just throw everything into my cupboard under my TV and eventually, when I feel satisfied, I'll build some sort of metal housing for both amp and computer.

I really care about super audio quality for the front channels, and would like cheaper amps for the other channels that produce little heat.

About my building skills .
I have built some less complicated stuff and have successfully soldered mod chips into xboxes before. And I guess that these kits are doable with a lot of patience. And maybe a new tip for my soldering iron.

More questions;
Higher voltage into the amp = better sound quality?
All I have to buy to get this going is AMP15-PS, 2 AMP5 or 1 AMP9, 2 toroids?
How much effect do I need from the 2 toroids?
How much heat will this amp generate when nothing is playing?

[Mackan2]

One more question, I believe that the truepath will perform better than AMP15-PS (true?), so I'm considering that one too. Do I need all 3 steps in the PSU1-series (PS, VR and SS). Well I realise that I need the PS and VR, but what is the Soft Start for?

[V-bro]

Hi, and welcome... A lot has been answered already so don't care if I answer stuff twice...

AMP15-PS can run up to + and -60Vdc, BUT this is max voltage and a better operating voltage would be +/-50Vdc in my opinion. This will make it live longer for sure. Plus a higher supply voltage won't make it sound any better. I would even go lower because I would like it stable with 4 ohm load as well. So unless you want it to be a dedicated 8 ohm amplifier you can best run it lower.

To run them all on one power supply is possible, but you would still need two transformers. Then you can series connect both and you'll have enough voltages to run amps on half voltage and some on full. If it is saving space this could still be a good option, if it is saving money you are after it will probably not help much because you can just as well run two AMP5 on one single (dual output 2x22Vac) and the AMP15PS on it's own (2x35Vac is what I would choose)...

Keep in mind that usually a transformer has a few volts more output voltage at a low/no load situation!! Like I have a 2x35Vac transformer here that outputs about 2x39Vac! Also at dynamic load (like an amplifier) an amp running on dual rail voltage can cause the voltage of the power supply to 'pump' meaning it will swing up and down and at transients it can even swing up far over the max. allowed voltage of the chipset! So keeping it on the safe side is not a bad thing...

Funny you have the DM602/S3, I have worked on modding the S1 and S2 versions and found some very interesting mods for those! Possibly some will also work on the S3, but I never opened one up so far. In any case the S1 had OK filter values (especially the capacitor for the tweeter), later on they found out that customers usually pick the loudest speaker as the best in a shop, so they did all they could to raise the 'voice' sound. They changed the tweeter capacitor value from 4,7uF to 6,8uF!! Changing it back on the S2 made it MUCH more mellow and MUCH less metallic! Then you could change the wirewound resistors for the tweeter for some metal film resistors, this will bring back more detail. There are more mods, but these changed the sound in a positive and most dramatic way... The filter is attached to the input terminal by the way, so it is rather easy to reach.....

Truepath, well some like AMP15 better, I have built AMP7, AMP15 and Truepath many times, also for others, some reported to me they liked the AMP15 better....

I personally am a BIG fan of the TK2050 amps, in the (near) future there will be a much more powerful power stage chip (STA517B) available making it about just as powerful as an AMP15 or Truepath, but the noise floor IS better....The standard chip (STA505) sounds just as good though, only it's less powerful...

[FFF]

OK
You want super audio quality up front, that means a 2050 or a 3020 based AMP.
An AMP-15 is good but total system will get bulky even if you CAN run on lower voltage (you don't need +/-60Vdc).

If front (L+R) is 2x30W rms, use a AMP-4, it should be plenty for home use, because these AMPs are -very- dynamic. It's really enough.
Rest can be simpler, so that's Center, Lrear, Rrear and that BassShaker I believe?
That's 4-channels. Use a AMP-9, not basic.

So:
1x AMP-4, has PS on board, only toroid needed
1x AMP-9, has PS on board, only toroid needed.
1x Toroid, of about 2x18Vac 400VA, to power them both.
1x metal casing, not that big

Then:
- put toroid in middle and maybe metal shield to left and right
- AMP9 mounted to left side of casing
- AMP4 mounted to right side, to bottom

But if want to go all the way: use 3 Truepaths, perfect sound, lots of power.
It will cost you, though.

OH:
- higher voltage CAN mean better sound quality, but this will be plenty.
- effect from toroids.....you lost me. VA?
- this is class-T. efficiency 75-90%. normal use: luke, maybe warm.

More:
You know that these "digital" amplifiers have a slight EMI/RF issue?
And with an surround system you will have long cables around your (living-) room?

It might give a problem, that's way a lot of people prefer to switch to active speakers/boxes.
Or they make existing ones active:
- a small mono amplifier like an AMP-11-LV (ready-made) inductors inside a alu-box (=heatsink too)
(and these are small because of design they need to be compact AND they don't need a big heatsink)
- a small laptop power supply say, 20V-3A
- both of them screwed to the back of a speaker.

Or you could:
- AMP-4 + toroid 2x18Vac 100VA in small housing in front (cable length acceptable)
- 4-channel signal cable to second box (under couch?)
- AMP-9 + toroid 2x18Vac 300VA in small housing under couch. (cable length acceptable)

Just some ideas.

+ about housing, cases: http://wiki.41hz.com/Housing.ashx checkout AMP-9-basic. The AMP-7 compares to big Truepath. The AMP-6-basic is powered by a laptop power-supply.
+ of-course, http://www.41hz.com/forums/showthrea...professionally if you want to have it done....can't see if prices include the amp itself. ask the dude.

[Mackan2]

OK, more questions coming up!

But if want to go all the way: use 3 Truepaths, perfect sound, lots of power.
It will cost you, though.

This is intriguing, would it be possible to power all three with a single PSU1-kit and say a 50V / 500VA toroid?

- effect from toroids.....you lost me. VA?

Yes.
VA = volt-ampere = an effect unit?

You know that these "digital" amplifiers have a slight EMI/RF issue?
And with an surround system you will have long cables around your (living-) room?

I don't like the sound of this! Is this really a problem for livingroom-length cables? I guess I have cables around 10 meters for my rear speakers and butt-kicker and 2 meters for my fronts. Still a problem? Found a few threads on the forum, will read more... I have access to a Sonic Impact T-amp, does it suffer from the same effects? (so I can hear it my self).

switch to active speakers/boxes

This will be my last resort...

+ of-course, http://www.41hz.com/forums/showthrea...professionally if you want to have it done....can't see if prices include the amp itself. ask the dude.

I kind of look forward to building this by myself!

To run them all on one power supply is possible, but you would still need two transformers. Then you can series connect both and you'll have enough voltages to run amps on half voltage and some on full.

I can't see how this is supposed to work, but I guess one toroid per needed voltage is easier, takes up as much room and cost sort of the same?

[V-bro]

Don't worry too much about EMI/RF issues, there have been more fairy tales about this than true facts. A Sonic impact T-amp isn't exactly the best performer, so if that doesn't scare you than no 41hz amp will. I bet you have some power supplies running in your very house that have far worse EMI/RF issues!

[krilli]

And building is fun, just wanted to mention it. in-case-of.

+1!!

Indeed.