[TheChairGuy]

The little Tripath/Class T mobile amps can be found for as little as $100 online....has anybody out there monkeyed around with them?  I thought I remember someone mentioning them a while back, but I don't remember if it was here at AC or elsewhere.

Little they are in size at 4.6 lbs, but they put out big power...150 x 2 (at 4 ohms) if you feed it a minimum 13.2 volts.  They even have hi and low pass 12db crossovers.  Seems like an interesting experiment.

One thing that does give me pause is that they are not in current production at Blaupunkt...Blau now only makes some Class AB amps for the US market.  Sometimes it's just a marketing blunder when these things happen - other times it's more than that.  The amp started out life at a $460 list, so there may be more marketing foolishness involved than anything else   .

Anyhow, anybody have some points of view on this? Ya' know, I've pissed away a $100 too many times in my life, so it won't kill me if it's a bust, but I'd like to save time and avoid issue entirely if it ain't worth my time and efforts.  The little Sonic Impact inspired me to try another peck up in the Tripath line.

BTW, I still love my little JVC, but I am quite curious about all this digital and Tripath stuff.

[Monolith]

I currently own four of these (along with the Carver ZR1600).  Once you remove the plastic casing and the bottom shell, the units themselves are quite small.  I highly recommend them for their intended purpose - car audio amplifiers.  Very clean sounding with great bass impact and small enough to fit almost anywhere.  

Since I have the Carver, I don't plan on using these for home audio, but it could make an interesting project on the cheap, especially in a dual mono 300w+ setup (each amp comes with a 'certification paper' stating what RMS the amp has been tested to).

[TheChairGuy]

Monolith,

HAVE you used them for home audio...or only car use? Have you used them for awhile...are they stable, ie', don't crap out?  If you have 4, you're the best judge of all.

My SAAB factory system needs a lot more help than just an hi powered amp (tho it would help, surely), I am more interested in using these for home audio purposes for kicks.  If it fails in that regard, using them for the car is always a safe option for that kinda' money.

Thx.

[Monolith]

I have only used them for car audio for about 4-6 months or so (I've forgotten exactly when I installed).  I never had any problems.  I used them with a/d/s components.  Gave a whole new perspective on "Another One Rides the Bus" by Queen.  Gotta love the bass with a digital amp!

The big difference between car use and home use is that home use allows better tweaking of the sound stage, etc.  So, I can't really comment on how they would do in the home environment, but there is nothing to indicate that they wouldn't perform well.

[TheChairGuy]

I have only used them for car audio for about 4-6 months or so (I've forgotten exactly when I installed).  I never had any problems.  I used them with a/d/s components.  Gave a whole new perspective on "Another One Rides the Bus" by Queen.  Gotta love the bass with a digital amp!

The big difference between car use and home use is that home use allows better tweaking of the sound stage, etc.  So, I can't really comment on how they would do in the home environment, but there is nothing to indicate that they wouldn't perform well.

I think I'm sold on buying, at least, one...but the temptation for two is whispering softly in my ear right now    Thanks for the input and feedback - just knowing that they still work 4-6 months down the road is helpful.

[mgalusha]

ChairGuy,

What are you going to use for a power supply? You'll need a bad ass power supply to drive it. To produce 300 watts with only a 13.2V input means 22.7amps and that's if the amp was 100% effcient, which of course it's not.

Getting that kind of current out of a car battery isn't a big deal but it's likely a very expensive proposition if you plan on running it from 115V mains.

Not trying to discourage you but it's something to keep in mind.

Mike

[TheChairGuy]

Yep Mike, was thinkin' something along those lines.....but I didn't know the technicalites of how BIG a battery is needed.

I sent an e-mail inquiry over to the guys in Winchester, VA (BatteryMart.com) that I just bought a 12v / 7mAh battery from (I don't know how they sell it for only $9.95 - it's half the cost of anywhere else I looked).  A large sealed acid battery was something along the lines I was thinking of...but I'd let them answer it if I need car or motorcycle sized batteries.

Why would it be expensive to run off of 115v mains...do you mean the cost of a battery and pure sine wave inverter (the best way to run it -those guys are mondo expensive I've researched)...or the electricity used and involved in the running of it?  At 90% or so efficiency, how could it be expensive?  Shouldn't it be less than any traditional Class AB amp to run?

Maybe there is a technicality here that I'm not figuring in to the equation??? Thx in advance.

[mgalusha]

Ahh, I didn't realize you were planning on using a battery. In that case you would only need enough power to keep it charged.

If you were planning on running it from AC only that is were it gets expensive. A Hammond transformer capable of supplying 12V @ 25A runs about $71 from Allied Electronics. This would come close to allowing the amp to reach full power. Add in the cost of some good rectifiers and filter caps and the power supply cost will easily excede the cost of the amp. Of course this is true in many amplifiers, the power supply is often the most expensive part.

The reason you need such a high current power supply is because the voltage is so low. The amp actually has a DC-DC voltage converter inside to raise the voltage up to a level high enough to produce the rated output power. You need approximately 35 volts at the speaker with an 8 ohm load to reach 150watts (35V and 8R works out to 153Watts). If the amp is 90% efficent one would need about 39Volts on the rails to produce this output. Approximatly 4.4 amps will be required at this voltage as well.

Of course since the battery (or supply voltage) is 13.2V this has to be increased. To raise the voltage means transforming current into voltage as nothing is free. Hence if you wanted 5A and 40V you would need 15A of current at 13.2V - and that is just for one channel. Big transformers are not cheap. You could probably get by with a switching power supply but that's not usually in the realm of DIY.

Does this make sense? The numbers are approximate but fairly close.

You could run it off of the 7Ah battery, but at full power (which you won't likely hit very often) it would last about 15 minutes. 7Ah means 7 amps for 1 hour. At 30 amps that is a bit less than 15 minutes. Of course it will last longer at lower power levels. Using a lead acid battery inside is not a very good idea because of the hydrogen gas produced. Don't want your house to go up like the Hindenberg. A sealed gel-cell is fine though.

Mike

[GUNN]

Monolith,

I heard from the car audio forums that these amps were pulled from shelves because emit a lot of RFI and kill radio reception. Did you notice a difference running these Blaupunkts in your car?

[Monolith]

Monolith,

I heard from the car audio forums that these amps were pulled from shelves because emit a lot of RFI and kill radio reception. Did you notice a difference running these Blaupunkts in your car?

I was not aware of this issue.  If you've got a link to the forum discussing this, please post it.  I'd like to read what the problems are.  The amp itself is inside a metal case with holes for ventilation.  Running it next to a radio might cause RFI issues, but I doubt the RFI is transmitted very far away from the unit.  Radiating RFI through the speaker wires would seem to be the most likely culprit.  That would indicate a poor output design.  I did not have an amp next to the receiver, and I never had a problem that I noticed.

[tubesguy]

The amp also comes with individual test results showing output power and current draw.  Mine is at home, and I'm at work, but I recall something like 51 amps(!) current draw at 400w bridged.  Kind of shot my subwoofer amp plans all to heck. - Pat

[TheChairGuy]

Ahh, I didn't realize you were planning on using a battery. In that case you would only need enough power to keep it charged.

If you were planning on running it from AC only that is were it gets expensive. A Hammond transformer capable of supplying 12V @ 25A runs about $71 from Allied Electronics. This would come close to allowing the amp to reach full power. Add in the cost of some good rectifiers and filter caps and the power supply cost will easily excede the cost of the amp. Of course this is true i ...

Yes, Mike, it did make sense to me.  Thx for padding down the technical stuff for the layman sect  

I would expect to need something larger than the 7 mAh SLA just ordered, but I could evaluate the amp with it initially, at least.  

Reality is, as I have a 12 x 12' listening and am well past Metallica and Thus Spake Zarathustra days so I'll probably only use a fraction of full rated power (probably cruise around at something like 20 watts) in everyday listening.  But, as with all high power amps, it's great to have the extra on reserve for those dynamic peaks. Realizing this in the past year has made all the difference in the enjoyment of music. Weak kneed amps simply ran out of gas on dynamic peaks.  This probably doesn't bother the SET crowd looking for 'purity' much - but it sure bothers me.  It's like having Ellis Marsalis getting an asthma attack while I'm listening to him    

I think, at this point, I'm too intrigued not to try one out on the battery I already have.  What's the worst that could happen - I sell it for $40 on ebay or something?

Thanks much for the important input and potential pitfalls  

[mgalusha]

Keep us posted on the results. I suspect in a 12 x 12 room at reasonable listening levels it will only have to provide a couple of watts most of the time. Even with 85dB efficient speakers 1 Watt is pretty loud.

I agree with you, running out of power with the consequent compression and reduced dynamics is not good. I have the JJAZ 1KW monos in the system right now (on loan until the RMAF starts) and the sense of ease at any volume level is great. The never sound strained and I cranked it up the other night until I bottomed out a woofer and there was no sign of reaching the limits of the amps.

[nhtran]

You guys need to check out the discussion below.  The amps run very hot...one member's amp blew up.


http://www.audiocircle.com/index.php?topic=11147&postdays=0&postorder=asc&highlight=blaupunkt&start=0

[TheChairGuy]

I bloody well did miss that topic, nhtran, and it was only 2-4 months ago.  Guess my head wasn't into the digital amp thing and I didn't pay ettention to it.  Thanks for bringing up and glad I asked if anybody knew anything about it...clearly many do.

Not that $100 will break me, but I think I'd rather invest in cooler runing products that don't have a prior repuation for blowing up.  Man, these hobbyist audio forums are great...might've just saved me some grief.  I like my speakers, don't want a mid or tweeter smoked.

Thanks again.