Tripath, Great w Klipsch

[leok]

The following design is great with Klipsch speakers. Note, for DIY types, you can purchase modules (complete pc assemblies) called "Eval boards" from Tripath for the 10W TA1101B or the 20W TA2020. I can help you do the input mod to remove the caps. The other mods will depend on your skill and patience with small circuits. See schematic attached to this posting. It is a .pdf file.

Tripath no caps

I have designed, produced, and distributed (including a few sales) a small stereo amplifier based on the Tripath TA1101B. My design is taken directly from the Tripath application scematic in the TA1101B data sheet. I have made one very important change in the input, and learned a few things about which components should be optimized.

My application is driving Klipsch Forte, RB-5, and RF-7 loudspeakers. I generally use a fraction of a watt .. never more than two or three Watts. I have done some work with tubes: currently I have a design that uses KT66s, PP, triode, no feedback. The tube amp is nice, but the Tripath is very very nice.

The input:

see Tripath's TA1101B Data Sheet:

"Application/Test Circuit" at Tripath.com

There is a 2.2uF electrolytic (C1) on each input because the input amp is biased at something like 2.5V. That cap has a huge impact on the sound. To get rid of it:

Observe static electricity protection rules. Until this circuit is complete, the Tripath input is floating and very vulnerable.

1) Use a floating, non grounded, 12V power supply. They are readily available.

2) Isolate audio input ground from the 12V ground and connect it directly to the TA1101B-pin 14.

3) Connect the audio signal directly to the resistors: R1. Now the audio is connected differentially to the input amps.

4) Bypass the audio ground (now connected to pin 14) to the circuit 12V ground. I use a 22uF electrolytic and 0.1uF ceramic. + connects to the audio ground. This step limits common mode noise which otherwise totally swamps the input circuit.

5) Insert a 7 or 8 volt zener diode between the audio and 12V grounds, cathode to audio gnd, to protect the chip input, esp pin 14.

6) Put big rf beads on all power, input, and speaker wires (you really should do this anyway with this amp). A single bead for each +/- pair is fine .. that's 5 beads total.

That's it. it makes a BIG difference.

Other tips:

1) rf beads (I already said it, but it's important).

2) nice 1.5 amp torroid output inductors

3) nice (mylar or better) output caps. I use .22uF because my speakers

are 8 Ohms.

4) nice 2200 uF electrolytics for VDD1/2 instead of 180uF

This is a beautiful amp: not big, not powerful, but a great match for horn speakers.

If I can figure out where to post a schematic I'll do so. Also, I;ll try to answer any questions right here.

[j-malotky]

Leok

How flat is the performance? Can you post your test data and pictures of your AMP.

I may be interested in a set to drive my Khorns sometime in the comming months - after my new house is built.

At the moment I am taking to a guy who builds tube amps who has a production sterio 40 and 70 watt models. I am negociating having him make a 40 or 70 watt monoblock from his currnet design.

Thanks,

JM

[leok]

JM

I tried to send an email message. There were several server errors, but they seem to come with the territory. If you don't get the email, let me know here and we'll try again. You can email me directly clicking on the email icon below.

I don't have measured data. If you go to the Tripath.com website and look at the TA1101B datasheet it pretty much tells the story. What I think is significant is that the distortion and noise remain below 0.1% as power drops below a Watt. This is what originally attracted me to the circuit. It "sounds" very neutral. In fact, it has no particular sonic signature. Plenty of detail and no harshness.

I've tried the amp with KHorns, and it seemed to work fine.

[j-malotky]

leok

I did not get your email.

I did visit your website and looked at your PDF's etc. I have never seen anything like your "class T" amps. When I think of circuit board or chips that amplify I cringe thinking of my kids boombox amd sound cards with onboard amplification etc. Being a Class A - ish audiophile for the last few decades - I guess I have some steriotypes (pardon the punn) to get over.

On the upside, with the costs of circuitboards etc. Im sure the cost will be much less than the custom tube job I have been considering!

Not being an EE, I do not fully understand how this is possible with such low voltage etc.

If this works, I may invest in your company!!!

I will be interested in what others on this BB feel.

JM

[leok]

JM,

Take a look at the entry below in this BB "B@W opinions" posted by techguy13. There is a note by TBrennan, posted 21-Apr.

It doesn't require much voltage for good sound .. mostly just low distortion, and with horn speakers: low distortion at a fraction of a Watt.

Power has been a marketing tool for amplifiers since the late 50s. When transistor amps hit the market, the power craze went nuts .. one reason is most transistor amps have excessive distortion at low powers and only sound good on power hungry speakers like acoustic suspension or other power-hungry types like Magneplaners (which are beautiful sounding speakers, by the way .. I just happen to prefer horns).

People are justifiably suspicious of low power amps: the concept is counter to 40+ years of audio industry mainstream culture. (But you're on the Klipsch BB, and Klipsch, and people who like horn speakers have held on to an approach that doesn't simply follow trends.) Look at the growth of SET and ss class A. Recently the Quicksilver Audio "Horn Mono" amp was released, and reviewed in the May 2002 Stereophile mag. I think some sanity is returning to audio.

Concerning my amps, have you tried sending me a note by clicking the mail icon below. I thik that will work.

By the way, tell us about your plans for a listening room in your new house. Will the Khorns be new or do you already have a pair.

leok

[j-malotky]

leok

I took your email address off of your profile and sent you an email. I don't think the email feature on the bbs works.

JM