T amp questions.

[gvr4ever]

I searched for "T amp" and found threads under all the sub amplifier forums, so please forgive me if this is in the wrong place.

I want to know if this amp http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-952
could power these speakers.

http://www.polkaudio.com/homeaudio/products/r30/

I bought the polks on outlet for my gym, but we moved to a larger place and the amp I was using is too far away and hooked up in a totally different place in the house.

The use is for a gym and I would be plugging a MP3 player in to it. I don't need anything insainly loud, just loud enough to hear over the noise of a treadmill.

 

[preiter]

The manual says they get 89dB / watt, which is fairly efficient. I think it would be ok depending on how loud your treadmill gets.

The actual power output of the T-Amp is 8W / channel driving 8 Ohm speakers, btw.
This thread belongs in the Class-D amplifier forum, where you find lots of discussion on the T-Amp.

 

[gvr4ever]

Thanks for the information. I think I might just get it. Two acually. I have some (don't laugh) bose for the bed room and they need a amp too. They are good enough to sleep too and I bought them over 10 years ago. We've all made our mistakes They acually sounds pretty crisp and clear. They don't have any bass, but I don't want that for background music while falling asleep.

The tread mill is pretty quiet. I was acually using computer speakers that had a baby sub, but I want to put that back in the garage so I can have some tunes while I work on the car. I got some long projects comming up and I just have to listen to music while I'm working.

If a mod comes along, please move this to the correct forum.

Thanks

 

[phn]

9-10W is maximum into 8Ohms for the Sonic Impact. It produces about 5 useful Watts. It's real Watts, but still just 5. I would say Polk is correct when they say <20W.

I would go for an LM3875 chip amp. Cheap and easy to build. A 24-0-24V (100W) transformer will give you 2x25W@8Ohms

 

[gvr4ever]

9-10W is maximum into 8Ohms for the Sonic Impact. It produces about 5 useful Watts. It's real Watts, but still just 5. I would say Polk is correct when they say <20W.

I would go for an LM3875 chip amp. Cheap and easy to build. A 24-0-24V (100W) transformer will give you 2x25W@8Ohms

It says 10 watts RMS, not peak. Where are you getting that it just has 5 real watts?

Anyway, I already ordered it. I'll let you know how it turns out. I think it will work. If not, I acually have a 20 watt solid state healthkit amp that I was going to use, and it does work, sort of, but the volume and balance knobs are not working right. They have a short in them. At 20 watts, the speakers were much louder then I expected and sound was really comming out of only one speaker.

I was going to fix the old solid state amp (and probably will in time), but I needed a quick and cheap fix. The old amp acually sounds decent, but it needs to cleaned out and checked over. It would take hours that I don't have right now. Hopefully I just need to hunt down a short. I hope the knob doesn't need to be replaced. It doesn't feel loose or sloppy, it's just that the sound crackles all over the place if you try and move it and the sound stopes comming out if you touch it the wrong way. It was a freebie.

 

[phn]

At 9-10W the SI produces about 10 pct distortion. At 4W it's 0.2 pct.

 

[gvr4ever]

I did do a little research before I bought this amp and I read some good reviews. I was worried about it not being able to push the polks, but after reading a lot of reviews, I think it will work.

Some of the reviews are almost unrealistic as these cheap little amps are getting MAJOR praises.

Amazon has a lot of reviews. Some bash the quality while others praise it. Some people simply hooked it up wrong and fried it. I think a lot of people used the wrong power adapter for it. I tried to find a cheaper one, but I couldn't find anything cheap that was in spec of what the amp wants.

One good review is from here.

http://www.6moons.com/audioreviews/sonicimpact/t.html

*WARNING* link is not work safe due to some of the advertizing on the site.

I ordered power adapters them it so I don't have to always use batteries.

http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=120-1135

 

[phn]

I'm a big fan of the SI. I second everything written about it. With my old Altecs with a sensitivity of 96-98db, it's more than enough.

For every 3 db less you have to double the Watt. So 20W into your speakers is roughly 4W into mine.

I'm not trying to scare you off or anything. None of us knows for sure until you've tried it. I hope it will work out.

 

[gvr4ever]

I'm a big fan of the SI. I second everything written about it. With my old Altecs with a sensitivity of 96-98db, it's more than enough.

For every 3 db less you have to double the Watt. So 20W into your speakers is roughly 4W into mine.

I'm not trying to scare you off or anything. None of us knows for sure until you've tried it. I hope it will work out.

Ya, it will probably be close. I hope I didn't make a mistake. I read one good review from someone that had 90db speakers and mine are 89db, so it will probably be close.

Also, from some of the reviews I've read, it sounds like it runs stronger/better from a power adapter then from batteries.

I'll update how it works when the stuff comes in. I acually bought two and I know for a fact that it will work with the bose I have. I'll test it on the polks and if it just doesn't work out, I can return unopned stuff back to partsexpress. I'll be out a little bit of money, but live and learn I guess. I'm still a newb.

 

[gvr4ever]

Ya, it will probably be close. I hope I didn't make a mistake. I read one good review from someone that had 90db speakers and mine are 89db, so it will probably be close.

Also, from some of the reviews I've read, it sounds like it runs stronger/better from a power adapter then from batteries.

I'll update how it works when the stuff comes in. I acually bought two and I know for a fact that it will work with the bose I have. I'll test it on the polks and if it just doesn't work out, I can return unopned stuff back to partsexpress. I'll be out a little bit of money, but live and learn I guess. I'm still a newb.

Silly 30min edit lockout. Anyway, I have a suspesion that the db rating on the r30s are wrong (missprint). My first set of speakers I ever bought were Polk Audio Monitor5 JRs and they are rated at 90db. However, I tested old against new and I have to turn my amp up more to get the same volume out of the older speakers. The older ones kick the snot out of the new ones too in build quality and in mid range and the trebble soars compared to the r30s. I got them on outlet for $110 and the original MSRP was $399. I feel sorry for anyone who paid that much for them. Anyway, the db rating on them might acually be a miss print because they seem to be way more effecent then my older polks.

 

[gvr4ever]

Update and review:

To be fair, I tested on my HT speakers because they were rated at 98db and a Sony SACD player.

After about a two hour break in, things really started to smooth out and sound very sweet.

All the insain reviews are true. Tube like? I probably depends on the tube. I've heard tubes that were warmer/softer sounding, but I would not laugh at any reviews that say they produce a tube like sound. From what I've heard, they are right up along if not on par with some very costly seperates I've heard.

It's a music lovers dream come true! The T-amp kicks the ever living snot out of any Harmon Kardon or Denon amp I have ever heard.

If you want to use one as a main amp, pay a little more for the super t amp. 100% worth it and then some.

 

[preiter]

For every 3 db less you have to double the Watt. So 20W into your speakers is roughly 4W into mine.

I thought 6 dB was double the power.

 

[phn]

I'm not an engineer. 6 db is twice the gain. I don't know if that translates into twice the power. Some helpful sould here might want to enlighten us?

What I do know (or at least think I know) is that for every 3 db less sensitivity you need to double the power.

 

[gvr4ever]

I was too lazy to read in my LDC book, but I googled it. I thought it was like 20-30 watts for ever 3db, but it's twice the power.

http://www.anandtech.com/printarticle.html?i=1317

I acually bought two baby t-amps. One was going to be hooked up to some polks rated at 89db and it works, but it's not enough. If I turn it up a lot, it gets loud enough, but I don't want to dammage my $30 investment. The t-amps sounded better then I thought they would. For the first time in life, you can acually get something good for not a whole lot of money. So, I'm going to take my main stereo amp to power my gym speakers and hook the t-amp up to some polks that are rated at 90db. 90db rated speakers seem to be the least you want to run with the little amps.

The test was acually on my rear HT speakers. I acually want to test them on my fronts HT speakers that are rated at 100db. Yikes. As it is, the t-amp gets LOUD barly turning it up with 98db rated speakers.


Most importantly, they are very clear. They DO need a break in. I can hear them clear up the longer I use them. At first, they had too much trebble, not enough bass and they sounded like a cheap best buy amp or something (still good for $29.99). They are smoothing out and I'm starting to hear nice bass hits, the mids are getting really clear and the bass is comming out. Strange little things. I'm hearing things in my music that I've never heard before. They clear up a LOT in about 2-3 hours and that's when I wrote the first review. They acually seem to be clearing up even more. I read that they need a full 300 hour burn in time to fully break in. That seems like a lot, but if you try them, do NOT judge them out of the box.

Well, I think I am going to go play with the main HT speakers and see what they sound like.

 

[preiter]

Ah, a bit of googling had the answer. I thought that the formula for a decibel was 20*log10 (x), but that only applies to voltages.

It's 10 * log10(x) for power, so 3dB is correct.

 

[AndrewT]

Hi,
a poster that is prepared to do his own homework. TOP MAN.
and the correct answer.