Hafler Amp - PROBLEM????

I purchased a Hafler TA1600 for a decent price after seeing a lot of good comments about the amp and thought it might be a step up from my Alesis RA100.

I tried it through my Mackie 1202 into my DAW through a Lynx L22 card into my Event 20/20s using both a recorded project and a commercial CD through a stand alone player (not the computer). I hooked it up and was a bit surprised that the sound wasn't very good. It reminded me of a transistor radio albeit with crisp mids and highs - basically lacking low end. Quite different and have less power than the Alesis.

Afraid I had been screwed, I took it to an electrician/musician friend of mine for diagnosis. He ran it through some tests - most of which seemed to indicate it was fine. He ran a tone generator through it into a single speaker cabinet the whole range of available frequencies without a problem. He then played both an electric and bass guitar through it which also seemed fine.

Relieved, I took it back home to see if I had bad cables or some other anomaly that might be causing it. The odd kicker is that the only normal sound I could get from it was with the connectors plugged in to the 2nd click (sleeve - regardless of balanced or unbalanced plugs) with the amp volume knobs OFF???? which sounded great. However, when I would turn up the volume knobs it would seem to morph back into the transistor radio type sound. Push the connectors in all the way and its back to the bass-less bright sound.

All the cables I tried were good and it made no difference whether I ran through the Mackie, the DAW, or direct from the CD or MD player - same phenomenon. I called my friend back and he said return it, it's bad!

Anybody have any experience or knowledge of what's happening? I've been in touch with the former owner and he has agreed to refund my money but I thought I would check here before I do. Here are his comments:

Doesn't make much sense to me. I ran it here for over an hour with a Carver CM2002 preamp playing cds from my JVC player through a Teac 10 band eq and powered my Cerwin Vega V15-X 500 watt studio monitors and it sounded great.

It sounds like you have the speakers out of phase to me. Zero out the volume of one side and see if you get better bass response with just one side running.

Thanks for the responses.

Yes, I initially swapped out the amps replacing the Alesis with the Hafler. It doesn't matter what way I set it up - the sound is the same except for when I insert the plugs half way in.

From CD to DAW to Lynx to Mackie to Amp to Speakers
From CD to DAW to Lynx to Amp to Speakers
From CD to Mackie to Amp to Speakers
From CD to Amp to Speakers

From MD to DAW to Lynx to Mackie to Amp to Speakers
From MD to DAW to Lynx to Amp to Speakers
From MD to Mackie to Amp to Speakers
From MD to Amp to Speakers

From Sonar to Lynx to Mackie to Amp to Speakers
From Sonar to to Lynx to Amp to Speakers

I will try what you Mod suggests and get back.

ORIGINAL: fwrend

Mod Bod - Turning down the volume of one channel makes no difference to the sound.

While I describe it as sounding like a transistor radio, I don't mean that it is "bad" - as I said the highs and high mids are clean and crisp. But the only time lower frequencies are heard is when the source input is inserted only halfway.

Could there be that much difference in coloration between the two amps?

Are you pluging in a stereo ( tip .ring . sleeve )connector? or are you only hooking it up on the hot and not connecting the ground? I can't imagine what your talking about here except to say it sound like you definately are experiencing the input or speaker outputs out of phase or somehow one side isn't grounded on the input.

Sorry guys, I am trying to be as brief, specific, & consice as I can.

Yes, balanced/unbalanced was a thought but I've tried all of the configurations with both balanced and unbalanced cables as well as all inputs/outputs including the RCA amp inputs from the MD & CD players. I've even tried the speaker posts on the amps outputs to the speakers instead of the 1/4" outs. It makes no difference using bal or unbal cables - when I plug them in halfway (i.e. second click which places the tip on the ring part and the ring on the sleeve part of the input) is when it sounds like it should. Same results. It doesn't make sense to me either.

Another thing: I have also tried using different outputs from the Mackie: 1/4" CR out, 1/4" Main out, and XLR Main out. They all react the same when plugged in halfway - i.e. good sound with the amp volumes OFF. I might add here that the volume seems full as if it is indeed bypassing the volume control all together.

But here is where there is a slight difference and where an audible phasing occurs (I use the word "phasing" descriptively only):
1. Push the bal or un-bal plugs from any of the 1/4" outs of the mixer ALL the way into the amp inputs and there is NO sound until the volume knobs are turned up. When the volume of the amp is raised it fades a bit at 50% then phases into the aforementioned transistor radio sound from there on up to full volume.
2. But, push the bal plug from the XLR out of the mixer ALL the way in to the amp input and there IS still sound but not as good as when it is in half way. Again, when the volume of the amp is raised it fades a bit at 50% then phases into the aforementioned transistor radio sound from there on up to full volume.

p.s. I've also checked the wiring of the cables both old and new - mogami gold plated XLR-1/4"TRS wired Pin 1 to Sleeve, 2 to Tip, & 3 to Ring.

Is it possible it's just a low power amp... it is... and you're somehow getting it to operate in bridge mode and perceiving that it's louder when you do?

just a guess.

The trans NOVA circuit may have some sort of failure mode that creates symptons like these that are unfamiliar with other amp designs.

another guess.

I suggest you contact Harmon.

good luck,
mike

"Yes, balanced/unbalanced was a thought but I've tried all of the configurations with both balanced and unbalanced cables as well as all inputs/outputs including the RCA amp inputs from the MD & CD players. "
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I know this is a lot to read but yes, I've tried the RCA inputs together and indepently. Same issue.

I have the schematic for the Hafler TA1600 in PDF that you can save and print to take to your tech.



JD...

Not a problem and you're welcome. I remembered I had one for it and I hope it helps you get it fixed. One day when I can find the time I'll try to get mine fixed too. :)

Good Luck! JD...

Losguy,

I PM'd you a link to the PDF schematic for the TA1600.

Regards, JD...

I have the exact same problem with my TA 1600. Driving me crazy!!!!
Did you figure out the cause?
I could also use a copy of the schematic...please...

Yeah at first I was sure I goofed up the wiring but it is not an external issue.
Something is wrong with the circuitry. I'm going to open her up today and see if anything is obvious.
I could really use the schematic, would make tracking it down a bit easier.
I will post the results here so others can benefit from my experience with this as it seems to be a common problem with this model.
Thanks for your input Bill.

OK, I found the TA1600 schem, so you can PM me your email if you want it.

iron25 - please do keep us posted. Wish I could help but I haven't had the time or resources to have mine in the shop. I'm sorry for your woes but I am glad to know that someone has encountered similar problems.

bill - there is no external switch (or internal for that matter) that I can find. Not sure about the grounding issues as both had the same power source - I'll check to see if it makes any difference with thogh.