was HYPEX amps cheap surround system

[JR.]

OK I need somebody to talk me out of this (hypex digital modules).

I recently upgraded my TV and direct TV receiver, then moved a good for computer speaker system over to the TV... Night and day better than the cheesy speakers inside the flat panel TV, but I know it could be a ton better. (I recently turned the bass tone control all the way down and the computer speaker sub now sounds better, there was some odd artifacts coming from it).

I should probably buy a cheap AV amp to decode 5.1 and deliver 6 channels of amp. I don't need much power. Even the 180W hypex is probably too much.

The smallest Hypex module is 180W UCD180HG (70EU) so 6x plus conversion for USD $466

Then a hypex switching PS SMPS1200A180 1200W at rail voltages for 180 amp module 180eu or$200

So with shipping roughly $700 for modules that still need to be packaged.

I have 2 different pairs of decent hifi speakers, one needs to be reconed, but I already have the recone kit. I also have a big honking sub that has been sitting in my living room for a couple decades. So I only lack one full range speaker... and 6 channels of amp, and decoder...

Being cheap, I should probably buy a AV receiver with modest power. A couple I looked at don't directly drive the syb, but expect a powered sub.

Oh well... I know I can design and build an amp from scratch for less than $700, but probably won't sound as good as the hypex modules.

decisions decisions decisons.....

JR

[Speedskater]

Why not think about the serious DIY chip amp kits by Tom Christiansen?

Key features of the Modulus-86 Rev. 2.1:

65 W (4 Ω), 40 W (8 Ω) output power when using the Power-86 and recommended transformer.
Vanishingly low 0.000061 % THD (1 W, 8 Ω, 1 kHz).
Ultra-low 0.000067 % THD (40 W, 8 Ω, 1 kHz).
Ultra-low 0.00038 % THD+N (40 W, 8 Ω, 1 kHz).

http://www.neurochrome.com/modulus-86-rev-2-1/

[mediatechnology]

Thanks for the link Kevin.

I have a Denon integrated amp that was given to me with both power amp sections trashed.
I've been looking for some boards like these and may be able to use them if the existing transformer voltage isn't too high.

[JR.]

Why not think about the serious DIY chip amp kits by Tom Christiansen?

Key features of the Modulus-86 Rev. 2.1:

65 W (4 Ω), 40 W (8 Ω) output power when using the Power-86 and recommended transformer.
Vanishingly low 0.000061 % THD (1 W, 8 Ω, 1 kHz).
Ultra-low 0.000067 % THD (40 W, 8 Ω, 1 kHz).
Ultra-low 0.00038 % THD+N (40 W, 8 Ω, 1 kHz).

http://www.neurochrome.com/modulus-86-rev-2-1/

Thanks, that's interesting but only 40W @ 8 ohm is not much. [edit] oops 3886 is linear part[/edit]. The slick thing about Bruno's class D topology is that he uses the output filter lag to create the PWM oscillation.

The 3886 by itself is rated for 0.03% thd which is probably adequate for (my) TV speakers. I was thinking 180W was more power than I need, 40W is borderline too low.

I recall back in the 70's a few of us threw together a simple 75W amp, class A/B but a single pair of devices could deliver the 75W with a simple topology and modest heat sink.

Looking at the same website as 3886 TI has a TAS 5611A rated at nominal 125W (>50W @ 8ohm). These guys have been busy since the last time I looked. FWIW I use a small SMD TI class D amp in my drum tuner but thats < 2W.

I need to do some more homework, thanks I think you guys talked me back from the ledge for now... If I can live with 40W I can just throw a bunch of 3886 in a box,,, maybe bridge the sub for more power.

JR

[edit] Interesting 3886 cost $7 for one channel, while 5611A is $8.50 for 2 channel... hmmm did I mention I'm cheap? [/edit]

[mediatechnology]

I think the Neurochrome amps (IIRC) embed the LM3886 inside the feedback loop of the LME49710 to obtain lower distortion.
Its a current-boosted LME49710.

[ricardo]

I've got a similar requirement. I want 8+4 channels for a Periphonic (with height) Ambisonic Surround system. I've got the 8 speakers and have designed the subs (4 off) and how to mount the speakers to the ceiling.

After ooing & aaing etc. I concluded it would be simplest & cheapest to buy some old AV receivers. Those without digital inputs (ie all analogue in) are going for a song as they can't be used with da new digital sources.

The smallest & cheapest for each manufacturer all seem to advertise 50W/channel though I would take that with a large pinch of salt. Probably a bunch of 3886s.

Its one of those projects which may never see the light of day. The 8 speakers are still in their boxes after 8 yrs But I have cleared the space in the shed I live in

[JR.]

I think the Neurochrome amps (IIRC) embed the LM3886 inside the feedback loop of the LME49710 to obtain lower distortion.
Its a current-boosted LME49710.

Yes I looked at the link.

The 3886 uses a quasi-complementary output stage (all NPN power devices) so the distortion is caused by over compensating for the slower side.

That said the bare 3886 doesn't completely suck at <.03% thd, probably good enough for (my) TV sound.

right now it's a toss up between the lower tech 3886 (class A/B) and slightly higher power and lower cost class D 5611A.

Class D has more glue parts (and more pins), but single PS (actually two + supplies ) vs split...
------------
@ Wayne, I guess it depends on what kind of PS your old receiver has. The 3886 will be happy with conventional split supply.

JR

[JR.]

I'm still chewing on this... The class D looks smarter (2 channels per chip), but the 3886 is more old school (class AB).

I have the PS inside a 4x250W amp I built in the '70s but the +/- 75V rails are too much for modern IC amps.

JR

[JR.]

I've been soaking this in beer over night and I am leaning toward the low tech 3886 even though power is marginal low. I may bridge two or do something different for the sub that will be the power hog.

Today's off the wall idea, is to slug the output of the 3886 with resistor (or current source) to the minus rail to increase the effective class A bias near 0V and reduce low level crossover distortion (actually shift it to higher voltage). The 3886 uses NPN power devices so logical to pull a current out of the output stage (?), but this might be looked at on the bench to confirm.

For the record I don't expect 0.03% THD to be problematic for watching movies, but this could be a worthwhile "cheap" tweak IF the dominant distortion is crossover (my assumption based on the quasi-comp topology inside 3886).

JR

[edit] I hate the idea of slugging op amps but for this all NPN power stage it may have value). [/edit]

[mediatechnology]

I think your neighbors would prefer the 40W/CH amps.

MCM have some great low-cost amp modules for subwoofers. http://www.mcmelectronics.com/product/50-6269

I'd look at Parts Express too: http://www.parts-express.com/cat/subwoo ... ifiers/332