Possible alternative to SI T-amp found

[Max_Andrews]

I came across this nicely priced unit tonight: http://sewelldirect.com/Ultra-miniat...ier_specs.asp?

It comes with an included 24V AC power supply and appears to be lower distortion, more powerful, and more versatile than the venerable SI T-amp. Spec sheet says 15Wrms in stereo, but it's bridgeable to 30Wrms mono. Both configs yield 0.05% THD and 115dB S/NR. It's really tiny at about 4"x3.5"x.75" high, so would be easy to fit into just about anything.

Here's the somewhat sparse spec sheet from the manufacturer: http://www.amphony.com/download/pdf/dsheets/A100.pdf

If the specs are to be believed, it appears to be a better option than the SI T-amp if you need a bit more power but want to maintain the small form factor the the SI T-amp is so famous for.

[brianpowers27]

This looks like it could provide a good solution for remote locations that require lower power levels (eg: in wall speakers on back porch.) I could also see using this as a power amp for a bedroom diy setup.

I imagine that in order to take advantage of 15watts rms (stereo) you should have an 86db or greater system.

[Face]

A more versatile, but pricier option: http://www.nuforce-icon.com/Product-Icon.htm

[Operandi]

A more versatile, but pricier option: http://www.nuforce-icon.com/Product-Icon.htm

The Nuforce is nice and the price isn't so bad when you take into account it also features a decent DAC and headphone amp.

Another interesting micro amp is the Winsome Labs Mouse. It uses two T-amps in a bridged configuration so it is significantly more powerful than the other T-amps out there.

[philiparcario]

A more versatile, but pricier option: http://www.nuforce-icon.com/Product-Icon.htm

looks like it will hiss see the caution at the bottom. too bad the price is good.

NuForce® Icon™

The NuForce Icon’s Applications:

As the core of a desktop audio system, the Icon connects to an Ipod, CD player, PC or Mac. To fully utilize the Icon’s sonic capabilities, we recommend high-quality monitor speakers with a sensitivity of 87dB or higher.

Via the best, jitter-free USB technology, the Icon operates as a USB DAC for converting a PC or Mac’s audio signal to high-quality analog sound.

For optimal headphone performance, the Icon includes a discrete, high-performance headphone amplifier.

For operation as an audiophile-grade preamplifier, the Icon’s linestage can be connected to a power amp or active speakers.

As a high-quality auxiliary power amp in a surround-sound setup, the Icon can be used to drive tweeters or rear-channel speakers.


Caution: If you have high efficiency speakers with sensitivity > 92db, you might hear high frequency switching noise.

[philiparcario]

The Nuforce is nice and the price isn't so bad when you take into account it also features a decent DAC and headphone amp.

Another interesting micro amp is the Winsome Labs Mouse. It uses two T-amps in a bridged configuration so it is significantly more powerful than the other T-amps out there.

the winsome is really truly overpriced. 400 bucks with the alps pot assembled is a lot more then 52 for the amphony amp or 99 for the nuforce and the nuforce has a dac and a sub out.

[Operandi]

the winsome is really truly overpriced. 400 bucks with the alps pot assembled is a lot more then 52 for the amphony amp or 99 for the nuforce and the nuforce has a dac and a sub out.

True someone looking at the Amphony probably isn't going to consider the a $300+ amp but I don't know if it's that overpriced. Its also a lot more powerful than either of those amps, and almost certainly of better quality than the Amphony. For $50 I wouldn't expect much in terms of quality. Either way it's an interesting amp.

Also the Nuforce is $250 not $99.

[neildavis]

the winsome is really truly overpriced. 400 bucks with the alps pot assembled is a lot more then 52 for the amphony amp or 99 for the nuforce and the nuforce has a dac and a sub out.

It's also not a "T-amp", which usually refers to something with the TA2024 chip running off of 12V. The winsome uses the TK2050 chip set with a 30V supply, so it should have 6 times the power of the T-amp in each channel. Nonetheless, I agree with the assessment that it is way overpriced.

I keep meaning to get back to work on an amp based on the STA328 chip, which would be a lot more powerful than the T-amp yet still be low cost. It's a 2.1 channel low-distortion class D amp that is supposed to be good for around 60W per channel, and it has 4 biquads per channel to build digital filters for crossovers and EQ. I actually have an evaluation board already wired to a power supply...just need some software to control it.

[philiparcario]

yeah I cued up the headphone amp not the intergrated one. so 250 is the price.

i had a lot of t amp's even some better made. higher power ones from red wine audio. vinny r was the builder I can't remember his last name. they are not that good. I also had some of flying mole's versions'. all of these amps are not that good. They all hiss. now that may just be my ears but they all hiss to me.
I hear the power switching in all of them except the clari-t by redwineaudio and in that case only when it was on battieres was I unable to hear hiss. It only had 7 watts and 4 hours of playing time between charges so it was a limited amp. Red wine has some better ones now but they hiss.
so the 52 dollar one will work just as well as the 300. By the way the flying mole was 800 and some of the red wine setups were 750 plus.

I have many gainclones no hiss many ska-audio DIY amps no hiss. Many commerical amps some hiss some don't. I have gainclones that are so quiet I can put my ear on a focal TLR tweeter that is 95db sensitive and have trouble hearing the hiss. I ended up going all gainclones with my focal gear because of the lack of hiss.

[lhwidget]

If I understand the technology correctly, all of the pulse width modulation (digital) amps have to deal with switching artifacts in their output stages (as well as possible noise from switching mode power supplies if they use them). Most of these amps I've looked at use regulated power supplies, not switching mode power supplies.

They remove the switching artifacts in the output stages with filtered outputs. All of the designs I've seen based on the Tri-path chips do this (including the T Amps? I'm assuming they are a PWM amp) with filter chokes on the outputs. It appears that they achieve varying degrees of success...

Has anyone seen the FR data for the gain-clone amps? I'm really curious what the bandwidth of these amps is...

[eyekode]

None of these spec's state the the load for the wattage. I am guessing that for the stereo mode the load is 4 ohm and for bridged it is 8 ohm. So if you want to run this amp in stereo and your speakers are 8 ohm expect about half the power.
That being said I am seriously considering one of these!

[lhwidget]

Hey Neil (cause it looks like you're light years into electronics),

If Tripath is out of business, where are the chips everyone is using coming from?

[neildavis]

If Tripath is out of business, where are the chips everyone is using coming from?

Good question, but it just looks like there are a lot of Tripath chips left over in supplier inventories. Look at this link: http://w01.ic-trade.com/eparts/TA2024.html. Lots of parts available, but all with old date codes. I guess the chips didn't sell, which explains why the company folded.

Cirrus bought the Tripath IP rights, so they now own the patents and chip designs. Cirrus has a very nice competitor to the T-amp chip (CS4525), but it obviously doesn't use the same Tripath design (different modulator & no feedback). Maybe Cirrus will reuse some of the Tripath technology, but so far that hasn't happened.

[lhwidget]

Thanks Neil,
Another question, am I interpreting the designs correctly? The digital amps all have 1 or 2 (big for an electronic circuit) inductors in each output. From what I've read, these filters drop the output heavily just above 20 kHz to catch processing noise.

If this is true, the little Amphony amp in the OP probably isn't filtered well, the case is too thin for the inductors & they are advertizing FR from 1 Hz to 70 kHz. It may be a bit hissssy...

[brianpowers27]

I am at best a novice in the field of electronics. Please help me with this question.

What would it take to bridge both channels of the T-amp together? Would this yield 30 watts at 8ohms? A stereo design employing 2 t-amp ta2024 chips sounds affordable. 30 @ 8ohms watts would be much more usable than 15 @ 4ohms.

[neildavis]

Thanks Neil,
Another question, am I interpreting the designs correctly? The digital amps all have 1 or 2 (big for an electronic circuit) inductors in each output. From what I've read, these filters drop the output heavily just above 20 kHz to catch processing noise.

If this is true, the little Amphony amp in the OP probably isn't filtered well, the case is too thin for the inductors & they are advertizing FR from 1 Hz to 70 kHz. It may be a bit hissssy...

The output inductors do not attenuate "hiss". If they are too small they will saturate and introduce distortion at high current levels, and if they are not the right core materials they can get hot due to internal losses. "Hiss" is amplified input noise, usually from the analog gain stages. The relatively low power rating of the T-amp (TA2024-based amps) means you can use fairly small output inductors without worrying about saturation.

The output filter is designed to work at a specific load impedance, so changing the load impedance can affect the cutoff frequency of the output filters. So at some load impedance the Amphony amp should meet the advertised spec. Also, one of the attractive features of the Tripath chips is that they switch at a higher frequency than most other digital amps, so the output filter can be designed for a higher frequency. For example, the application sheet for the TK2350 recommends an output filter frequency of 100KHz for 4-8 ohm loads.

[philiparcario]

I am at best a novice in the field of electronics. Please help me with this question.

What would it take to bridge both channels of the T-amp together? Would this yield 30 watts at 8ohms? A stereo design employing 2 t-amp ta2024 chips sounds affordable. 30 @ 8ohms watts would be much more usable than 15 @ 4ohms.

THEY ARE PRE BRIDGED T STANDS FOR TRI PATH AND they are not 3 channels. MAKE A SMALL GAINCLONE INSTEAD! I have gainclones in small boxes dead quiet . will handle 25 watts per channel

[brianpowers27]

THEY ARE PRE BRIDGED T STANDS FOR TRI PATH AND they are not 3 channels. MAKE A SMALL GAINCLONE INSTEAD! I have gainclones in small boxes dead quiet . will handle 25 watts per channel

I have no experience building even the simplest of amplifiers. WHere would I get started if I were to build a gainclone?

[philiparcario]

links for pre built on ebay plus links for parts on ebay

http://shop.ebay.com/?_from=R40&_trk...All-Categories

some audiogon sellers

http://www.audiogon.com/cgi-bin/cls....e-on-Gaincard-

http://www.audiogon.com/cgi-bin/cls....one-LM3875-diy


the 5 channel on ebay is mine the one from birk on audiogon is a small size . these amps don't hvae a lot of parts.

build link
http://myweb.tiscali.co.uk/nuukspot/...gainclone.html


more links

http://www.webring.com/hub?ring=gaincloneamplifi

you can get a well made one for under 200. the one I am selling on ebay is really good but it is 5 channels. the one in the clear plastic on ebay is a good build. he sold a nice plastic box one a few days ago for about 185.
I have a rugged looking one. really quiet one no hum no hiss. about 5 by 6 by 10 inches 25 watts per channel. very nice amp. i would sell it for 150 with shipping included. It is good for 8ohm. 25 watts per channel. it could be put in a smaller case.

[lhwidget]

Thanks Neil, I appreciate your patience.

I was trying to refer to the switching noise in my post, I really appreciate the info.

It looks like the little Amphony might be worth trying for a test amp after all.