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sonnya 26th January 2014 09:07 PM

A new TSSA amp is on the stairs.

We wanted to preserve the 2 stage design and on the same time lower the output impedance and distortion without changing the basic circuit design.

We have succeed in doing it with an lift in airiness in the upper region. From midrange and up. Better control in the Bass.

The basic circuit known in the TSSA V1.6 is exactly the same. But by carefully redesign the current sources we have been able to raise the openloop gain by 7.5 times.

All idle currents tracks really fine. Within a few seconds from power up, idle currents are set. Meaning true "power on and play".

There is no chip solution on the AMP only PURE DISCRETE solution.

We have ended up with an amp in the same formfactor as the TSSA V1.6 so it is upgradeable. All holes are identical.

It can be run at 400mA as well as up to 1.5Amp idle with prober cooling,

First measurements show:

  • Distortion level into 25W into 8R is 0.06%
  • Bandwidth is 1.4MHz.

The new board is named TSSA V1.7 and will be available within 2 weeks.

To be safe Monday the 10. of february.

The modules will be delivered assembled and tested. The only thing needed to be fitted is the mosfets.

There is also an TSSA V1.7 HV (High voltage) on its way, but we need to hear the sonics performance.

- Sonny

sonnya 28th January 2014 10:39 PM

2 Attachment(s)
Some preview on the Data from the TSSA V1.7

Bandwidth is 1.5MHz
Slewrate is 44V/us Not fast, but 2stage design make it not possible to exceed it with lateral mosfet.
Zout is 50mOhm.

THD measurements below is taken at bias current of only 250mA. So it is real class AB as well.

Noise about 5KHz is Notebook interface that plays with us.

THD into 24W 8R is 0.034%
THD into 1W 8R is 0.014%

Harmonics falls off nicely.

vgeorge 30th January 2014 12:23 PM

Just saw that.
Good news Sonny, I am interested!
Would be nice to have more info on the higher power version.
What fets did you use?

buzzforb 30th January 2014 01:13 PM

I would be interested as well. Idea that you have a lift in the top end "airiness" is pretty interesting, as I thought this amp was pretty phenomenal in this regard. Would you be willing to make room for multiple outputs?,assuming the FE can drive multiples.

sonnya 30th January 2014 06:45 PM

Hello vgeorge and buzzforb.

In last minute i have added an onboard LC filter. After i have talked with Vgeorge i have decided to ad it. The reason for this is that vgeorge asked me if i have had problem using SMPS500R from connexelectronics.

I have to state right away that there is nothing wrong with the SMPS500R but the scope result showed an ringing of 5MHz every ~4usec..
Regardless of what amp we talk about PSRR is vanishing low at 5MHz.
Only solution is an EMI filter -> LC filter the inductance should have resonance as high as possible (>6MHz) capacitance should also have an resonance above 10MHz.

The FETS i use is ALF16N/P16 or EZW20N/P20.

They are 250Watt package, but i would not use them for more than 80 - 100W into 8R.
The HV version will be able to run from +/-45VDC. The main difference on this standard and the HV version is that we have to change the cascode from JFET too Bipolar due to the higher voltage. It is an whole new PCB so i cannot say anything about sound quality before we have build the first set.

It was only planed to use one set mosfets.

George and i talked about an high quality amp for Horn systems. A note to this. I talked with Maz from Odense, about an NANO AMP. actually smaller than the TSSA but it will make more sense to keep the form factor.

So this so called NANO amp will be same size as the TSSA but it will be based on the circuit from the Mirand A2. But only with one set output transistor. It will be 20 - 80Watt into 8R and can be run in CLASS A and AB depending on taste.

buzzforb 30th January 2014 07:00 PM

I am up for whatever. Very much enjoyed the 1.6 although i need your help finding an issue that is causing oscillation. Think i fried a transistor probing around. Good to see you are dong well with your designs.

vgeorge 30th January 2014 07:10 PM

That's all good news Sonny!
Waiting for your tests then.
If I understand correctly, NANO will be for horn systems?

sonnya 30th January 2014 07:20 PM

Not only horn system. But it will be as quiet or more as the TSSA. Distortion is also better. Actually i think you would be very pleased with the NANO AMP.

Last week we had a listening session. Michael G. and I. My wife was also present. The amps was the TSSA V1.6 with V1.7 changes and the MIRAND A2.

Michael and I was sitting in the sweet spot. My wife was sitting sideways in another sofa. She was knitting. Now what amazed me was the she suddenly said that the MIRAND A2 sounded better! She is not trained in listening. But from a not optimum position she had no problem in hear the difference.

Bussforb : We will find a solution.

sonnya 30th January 2014 07:23 PM

The "NANO AMP" is not a low cost design and so is the performance.. not low cost.

I need to recalculate the BOM. But from the number of parts in the list, it is more expensive to build time wise.

vgeorge 30th January 2014 07:32 PM

We are waiting then!

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