Amp/Preamp Asylum: REVIEW: Tube Audio Design TAD 1000 Amplifier (Tube) by raindances

Model:	TAD 1000
Category:	Amplifier (Tube)
Suggested Retail Price:	$2600. pr.
Description:	100 watt per channel all tube mono block amplifiers
Manufacturer URL:	Tube Audio Design

Review by raindances on December 26, 2009 at 06:45:14
IP Address: 65.13.157.204 Add Your Review
for the TAD 1000

I owned these amps for about a year and these are my thoughts:

Using EL34 tubes the highs are hopelessly rolled off and there is a lack of detail. There is a hard nature to the mid range that makes these amps hard to listen to. Bass is also rolled off.

Using 6550 tubes, the bass gets a bit better and the top end gets a little more extension. The hardness in the mids remains.

I examined the design of the amps and traced out the circuitry and discovered some design "issues". Modifying the feedback circuit made some improvement to the mid range hardness but did not clear it up altogether. Adding some better smoothing caps to the power supply for the driver stage helped things a bit too. There is nothing that can be done about the rolled off highs or low bass as this is a function of the transformers that are not very high quality. The amps also have a very odd grounding scheme where the input RCA jack is hard grounded to the chassis and a star grounding scheme is not very evident.

As far as build quality, these were late models just before the end of the production run. Build quality was terrible with poorly routed cables and lots of soldering iron burns on the insulation and even a burned out section on one of the PCB's for the bias metering that had been poorly repaired with wire jumpers. I even found a couple of components that were not soldered to their tag strips !!

As far as using 12AU7 in place of 12AX7 - it works, but the biasing is very low on the curve and they run in their non-linear region. It also makes massive changes to the feedback circuit due to the reduced gain at the input. It is possible to rebias, but you start impacting design decisions further down the chain when you get to the long tailed pair of 6V6 drivers which are also under-biased...

I previously owned a Cayin TA-30 that I bought from TAD and it was a spectacular product. I have also owned various other tube amps; some just get it right, some don't. These TAD-1000's don't. Poor quality control, bad design choices, cheap components.

Note that the factory is now gone.

Product Weakness:	Rolled off bass and treble.<br>NOT high end audio amplifiers.<br>Not even good enough to be considered entry level audiophile products.
Product Strengths:	Really impressive looking. with lots of stainless steel.<br>They are fairly reliable.

Associated Equipment for this Review:

Amplifier: TAD1000
Preamplifier (or None if Integrated): PS Audio Trio P200, Acurus RL-11
Sources (CDP/Turntable): Denon DVD955 / Keces DA131 DAC / Monarchy DIP
Speakers: Vandersteen 2CE / Magnepan MMG
Cables/Interconnects: Not a believer
Music Used (Genre/Selections): Various jazz and rock
Room Size (LxWxH): 26 x 14 x 8
Room Comments/Treatments: Careful placement using RTA to verify response
Time Period/Length of Audition: 1 year
Type of Audition/Review: Product Owner

Amplifier:	TAD1000
Preamplifier (or None if Integrated):	PS Audio Trio P200, Acurus RL-11
Sources (CDP/Turntable):	Denon DVD955 / Keces DA131 DAC / Monarchy DIP
Speakers:	Vandersteen 2CE / Magnepan MMG
Cables/Interconnects:	Not a believer
Music Used (Genre/Selections):	Various jazz and rock
Room Size (LxWxH):	26 x 14 x 8
Room Comments/Treatments:	Careful placement using RTA to verify response
Time Period/Length of Audition:	1 year
Type of Audition/Review:	Product Owner