[mcgsxr]

lcrim - Vinnie is definately the guy of Toshiba 3950/60 "fame", and also plays over at Head-Fi.  Wayne at Bolder is the person that I chose to mod my Teac, but I do know that VinnieR also offers a set of mods - perhaps you can email or PM him for the details.

Larry you are right on the money that the PS seems to be the weak point here, and that is likely why a large portion of the mods that Wayne did to my amp centered around that area - better caps, shorter signal path, improved connectors, and the opportunity to play with power cords, all should add up to some decent improvements.  Now, for the ultimate, battery power could prove really good, but I think that since the rails in the Teac operate at some elevated voltage, it would take a bank of batteries, not that cute little 3a that is in use with the Clari-T amp...

ludavico - yes, the Teac will accept banana plugs, I use them at present, BUT not the dual kind, just the single kind.  By dual, I mean the single unit, with dual banana posts on it - the spacing is wrong for those, but you can use single banana plugs no problem.

[MattS]

I'm not a electronics expert. But since the Teac was designed for running  3 channels, would just turning down the level controls on the  unused Left and Right channel  get you a major increase the power supply capability to just the center channnel?  Is it really necessay to physically remove the L&R boards?

[Wayne1]

All the volume controls do is attenuate the input signal. If you want an improvement from the power supply, cheaply, you will have to remove the center channel board.

The only way to bypass the input board and the controls is to hardwire the input jacks to the input connectors on the amp boards. You would have to pull the main board to run the jumpers.

The amp boards do pull a fair amount of current. There are 3 voltages that the amp needs: 28 V 12 V and 5 V. You might be able to build a conventional PS for 28 Volts with a decent amount of current but you would also need to add regulators for the 12 volts to operate the relays and 5 volts for the Tripath control chip.

I do not think batteries would be a good solution. You would have to go to 36 volts and regulate down to 28 and 12 and 5. It will get a little busy. High current regulators are not inexpensive.

Adding a RFI/EMI  filter before the amp will help out quite a bit by blocking the noise from getting into your other components.

By changing out the switching power supply components, I have managed to build a bit more of a  "resevoir" into the PS so it is not running at the extreme edge of it's capabilities.

I am working on a power conditioner system that should help out these digital amps. It will offer balanced power and/or EMI/RFI filtration and isolation and surge protection. I will put up some pictures of a prototype in the BOLDER Cable forum.

[ludavico]

Mark - Ok, thanks.  Banana/spade adapters will have to do for now...

Wayne -  Can't wait to hear about your mods for the TEAC.   I am going to try 2 TEACs with the L/R amp board pulled in each, and use the center channel for "monoblock" oepration.  I am definitely interested in your PS and AC conditioning stuff.  

While I have the case off, is there anything quick and dirty I can do to keep the EM fields off the amp circuit?

John

[lcrim]

Since removing a board reduces power consumption, removing the board that is amplyfying two channels would produce the greatest reduction in current draw.  Perhaps the current draw would be equal for both boards but I don't think so.  By turning the unit into a "monoblock" by removing the board that is driving two channels, it seems logical to assume that you would achieve a greater reduction in the demands made on the PS.
Again, does removing the stereo channel board produce a superior mono amp?  I think it does.

[ludavico]

Wayne - I would really like to pull the power supply out of the amp case altogether (like Naim Audio).   How tough would it be be to remove the existing PS and put in a separate case, or perhaps just buy a third party PS and hook it up externally?  

Use something like an 8' umbilical cord for the PS connection to get the sumbitch out of the picture...  

John

MattS - You mad bastid, that is a great Krall album.  

[Wayne1]

Both boards pull the same amount of current. The boards are identical. They are both stereo boards. They can be switched back and forth inside the amp with no difference. The Tripath chipset used in the Teac is designed for two channel operation.

I mentioned pulling the center channel board so you could use the Teac as a stereo unit. If you are going to use them as "mono blocks," it doesn't matter which board you pull. There are actually four channels of amplification in the Teac. Only three are connected.

[dwk]

I do not think batteries would be a good solution. You would have to go to 36 volts and regulate down to 28 and 12 and 5. It will get a little busy. High current regulators are not inexpensive.

A better way to go would be to run B+ at 24 from batteries, and use a small xformer to provide the 12/5 feeds which presumably are low-current control/signal lines.  You'd lose some output power this way, but in most cases it wouldn't be significant.

[Wayne1]

There is a 7 pin connector that goes from the power supply board to the main board. It has two 28 volt lines, 12 v, 5 v, two grounds and the control signal for the relays.

The PS board can be mounted in another case.

If you are planning to go to that much trouble, you might be just better off getting a Tripath evaluation board and build your own PS and put it in a couple of cases.

http://www.tripath.com/TA2021B_design_tools.htm

[lcrim]

So-there is no practical advantage to the "monoblock" route.  You aren't unloading any extra demands on the PS by using the Center board.  
Tonight I will try to figure out how to solder a jumper from the input jacks to the input connectors to eliminate the volume pots.

[toobwacky]

I'm using the TEAC as a stereo amp. I was using one board for each channel. I just pulled the "center" board and although the amp doesn't seem to play any louder before the onset of clipping, it does seem to sound better using just the "L&R" board.  More open, better detail yet smoother, more air around each instrument and more precise location of instruments within the sound stage yadda, yadda, yadda...

TW

[Vinnie R.]

I do not think batteries would be a good solution. You would have to go to 36 volts and regulate down to 28 and 12 and 5. It will get a little busy. High current regulators are not inexpensive.

A better way to go would be to run B+ at 24 from batteries, and use a small xformer to provide the 12/5 feeds which presumably are low-current control/signal lines.  You'd lose some output power this way, but in most cases it wouldn't be significant.

Hey guys,

If you want to try batteries, I recommend you try two 12V SLA batteries in series to get 24V, and a separate 12V SLA that will be used for the 12V relay control and you can use a decent 5V regulator off of that 12V SLA to feed the Tripath input processing chip.  The 24V and the 5V are the more important ones.

You probably should also try making a simple RC time constant circuit to provide the delay for the relays (like 2 or 3 seconds).  

You can also check if you get a pop during turn-on after bypassing the relays.  If you get no pop, bypass the relays and forget the 12V supply and delay circuit

Have fun!

Vinnie

[albee]

Has anybody thought to try 4-conductor speaker wire to the L/R  binding posts used with a Y-connector to the inputs for 60 watts per channel?

[ludavico]

"So there is no practical advantage to the "monoblock" route" -Larry

As you probably gathered, I have absolutely no background in electronics.  

I really wish I did.

I still think there is a benefit to "monoblock" operation though because there is a full power supply behind each channel (compared to using just one Teac to power two channels).

I think what Wayne is saying is that it does not matter which board you use in each Teac.  But in "monoblock" operation you are still going to only hook up one of the channels in each Teac.  

As you and I both heard, it makes a positive difference to pull  one of the amp boards out. "Monoblock" operation just takes this one step further by utilising the power supply in each Teac  for driving one channel only.

Isn't Class T amplification fundamentally different than Class A or AB?    

I really wish one of the true gurus around here (e.g. Vinnie, Wayne, Dmason, etc) would shed some more light here...  

For example, lets say you pull the C channel board.  Does the L/R amp board perform better if only one of the channels is connected to a speaker load?

 

John

[ludavico]

"The PS board can be mounted in another case."  -Wayne

Do you think mounting the PS in a separate enclosure would be worth it sonically?

John

[toobwacky]

My amp is putting out between 6 & 9 mv of DC per channel.  From what I've read elsewhere, these are perfectly acceptable levels.  Still, I'd like to tweak this a little lower if possible.  Does anyone know what the 2 trim-pots on the Tri-path boards do?

Thanks.

TW

[Vinnie R.]

"But, as you and I both heard, it makes a positive difference to pull one of the amp boards out. "Monoblock" operation just takes this one step further by utilising the power supply in each Teac for one channel only.

I really wish one of the true gurus around here (e.g. Vinnie, Wayne, Dmason, etc) would shed some more light here...  
.

John,

Here is the way I see it:

If you are going to use the Teac for stereo use, disconnecting the amplifier board plugged into the center channel slot is a good idea.  Why?  Because yes, it does reduce some currennt draw from the power supply at idle to (power the relay and Tripath chips), but more importantly, it reduces noise on the power lines.  The Tripath chips have built-in high frequency switching signals (kind of like Class D, but with a more complicated switching scheme), and as a result, they do add some noise back on the power rails.  Eliminating the unused center channel board is a FREE TWEAK, so unplug your units and just do it!  

For those of you who are running two TEACs as "monoblocks," it makes sense to use the center channel board and remove the L/R board (for the same reasons explained above).  And as John mentioned above, when you use two Teacs that are each just using the center channel board, the power supply of each Teac only has to provide power to one channel instead of two, so it works half as hard and does a better job, and there should be some reduction in crosstalk as well  

You can also use one Teac and put each board into "Bridged" mode (modifiy it) to make it a two channel amp with twice the power of the stock Teac.  Or, you can use two TEACs that each use only one board that is bridged.  In this case, I call that true monoblocks as opposed to "monoblocks" that I put in quotes in the paragraph above (with the unused channel)  

Whatever path you choose, if you are using a preamp before the Teac, you really should try sending the signal from the RCAs directly to the input of the amplifer board.  Keep the signal path (and power supply path) short and sweet, and you WILL be rewarded  

Regards,

Vinnie

[Vinnie R.]

"The PS board can be mounted in another case."  -Wayne

Do you think mounting the PS in a separate enclosure would be worth it sonically?

John

John,

It probably won't make too much of an improvement.  An easier approach might be cut a copper sheet and put up a wall to separate the power supply noise from the amplifer boards.  If you really want to go clean, ditch the switching power supply and go linear regulated or battery.  Just my opinion.

-Vinnie

[Vinnie R.]

My amp is putting out between 6 & 9 mv of DC per channel.  From what I've read elsewhere, these are perfectly acceptable levels.  Still, I'd like to tweak this a little lower if possible.  Does anyone know what the 2 trim-pots on the Tri-path boards do?

Thanks.

TW

TW,

Use the pots to adjust the dc offset that you are talking about.  Connect a voltmeter to the outputs and slowly adjust the pots to get it at 0V.  BTW, 6 and 9mV is pretty much nil, so it may not even be worth the effort.  Once you get it at 0V, it will drift somewhat with time and temperature.  Those trimmer pots are CHEAP and "drifty," if you catch my drift  

[ludavico]

Vinnie,  Thanks very much for the info.

I would love to try a better power supply or batteries...I just don't have the backgound to wire something like that up.

Things are unfolding pretty quickly.  Two weeks ago I had never heard of Tripath, Hypex, LCaudio, etc.  After reading some posts here I decided to try the TEAC because I needed a cheap, lower-powered amp for our backyard system.  

The Teac stayed in the backyard system for ~2 minutes  

After a week of running the TEAC with some mid-fi gear I have around, I ordered a second unit.

Then,  Dan posts his findings of the Clari-T...    

Yikes, I guess these little buggers are the real deal.

I really want to live with the TEAC faux "monoblocks" for awhile to see if  their sound is really for me.

Geesus if it is, all bets are off on my next system.  

Trouble is the speakers on my short list are current hogs (e.g. Piega).  

Is there going to be a big brother for the Clari-T?

Thanks again,
John