All,
As promised, I am posting as many details of the upcoming Signature 70.2 Monoblocks as I have available. Because all these details contain over the maximum allow post length, I am breaking it up into two posts (this one, immediately followed by the other).
Just like the Signature 30.2, let me begin with describing what has changed the most with the Signature 70.2… the SOUND!
If fact, much of this post is very similar to the Signature 30.2 details post.
Here are the goals that I set out to achieve in terms of sonic improvements:
a) A warmer, and more seductive sound signature
b) Greater dimensionality
c) Added bass weight
d) Sweeter top end
e) Richer tone, without sacrificing any PRaT
Simply put, I wanted to obtain an even more musical and more SET-like sound in the midrange and top-end, and a weightier “push-pull” sound in the bass.
Lovers of tone and musicality (lovers of what a well-designed tube amp can do) will LOVE the new sound that the Signature 70.2 Monoblocks offer compared to the Signature 70s. However, just like the Signature 70, the Signature 70.2 ventures into territories that SETs simply can’t compete in such as the ability to drive less efficient speakers (power!), ultra-black background (going off-the-grid with SLA battery power), dynamics, bass control and articulation, etc.
Compared to the Signature 30.2, the Signature 70.2 monoblocks offers even better sound quality! The 70.2 features even better bass response, sound staging, stereo imaging, and spaciousness. This distinctiveness is attributed to the monoblock operation… the separate power supplies, complete isolation between the channels, and the change in the output stage circuit configuration (paralleled output mode). Into 4-ohm loads, you can also expect twice the output current.. and 70W per channel RMS.
Obtaining the new sound of the Signature 70.2 has been an extremely long and time-consuming process that has been going on for many months.
I can’t begin to tell you all how many times I have swapped in different parts, different values of parts, going back and forth listening to many different test tracks, going back and forth with measuring equipment, and even with different speakers. I refused to be satisfied with results that were only slightly noticeable, or results that did not meet ALL of the goals listed above that I was chasing long and hard for. I realized that to get the results that I was looking for, I would not only have to change certain critical parts used in the Signature 70, but also the design of the input and output stages.
Signature 70.2 Amplifier BoardThe amplifier board in the Signature 70.2 has been heavily modified in order to reach the sonic goals that I have mentioned above. Here are some of the changes:
1) New output filter design that uses all new, higher-quality components as well as all new filtering characteristics.
2) The new output filter components are now hard-wired together (point-to-point) and have the speaker output cables also hard-wired to them, thus bypassing the traces in the printed circuit board for an even shorter, cleaner signal path.
3) New PIO (paper-in-oil) input capacitor of an even higher-end grade
4) Modified input stage design, which also features higher quality parts such as resistors, new dc offset pot, etc.
The Signature 70.2 and The SMART ModuleThe next major goal of the Signature 70.2 (following the sonic enhancements) was to make the use of the SLA battery power
fool-proof 
. I am very excited to announce a new Red Wine Audio innovation that will be featured in ALL of our “off-the-grid” sealed lead-acid battery powered products and modifications going forward –
The Red Wine Audio SMART module! (
SLA battery
Monitoring and
Auto
Recharge circui
T)
This is a small circuit board (approx 2” x 3”) that will take the place of the mechanical On/Charge toggle switch that has been used in all of our existing products.
As detailed below, the SMART module will
eliminate the concern of accidentally leaving your SLA battery powered RWA product ON and forgetting to charge it (which results in significantly reduced battery life or even ending the life of the battery, as SLA batteries do NOT like to be deeply discharged).
Here are the detailed features of the new Red Wine Audio SMART Module:
1) Instead of using a mechanical switch to connect the SLA battery power to the load, the SMART module uses a high-current MOSFET (controlled by a small integrated circuit) to connect the SLA battery power to the load. The battery charger is also connected to the SLA battery via a pair of high-current MOSFETs that switch on/off both Charger + and Charger GND connections.
When the product is ON and running off of the SLA battery power, both the Charger + and Charger GND MOSFETs are OFF, so the charger is completely disconnected from the SLA battery. This isolates the battery when the product is on and prevents any ground-loops with other mains-powered audio equipment (e.g. powered subwoofers) when charging.
2) When the product is turned ON, the battery voltage is constantly being monitored via an integrated circuit on the SMART module. Once the battery voltage drops to a set threshold (this is set by Red Wine Audio at the factory for a 12V or 24V system), the battery will immediately be disconnected from the load (i.e., the load MOSFET turns OFF) and connected to the SLA Auto Battery Charger via a pair of the same type of MOSFETs that switch both the Charger + and Charger GND terminals to the SLA battery to begin the charge process automatically.
3) Turning ON the Red Wine Audio product that features the SMART module is simply done by pressing a momentary switch (see Signature 70.2 Front Panel details below). Turning OFF of the product that features the SMART module (i.e., removing the load from the battery and starting the battery charge process) is simply done by pressing and holding down the momentary switch for 1 to 2 seconds, OR as mentioned above, if the battery voltage drops to the set threshold limit while the product is left ON it will automatically turn OFF and begin the charging process. If the charger is not connected, the SMART module will still remove the battery from the load to prevent the battery from becoming deeply discharged.
4) When ON or OFF, the power consumption of the SMART module is extremely
low, so it draws virtually no power from the batteries.
5) The SMART module offers superb current flow from the battery to the load, as well as much enhanced reliability. This is because that compared to the mechanical switches used in all our past designs, the high-current MOSFETs used in the SMART module feature lower turn-on resistance (in the very low milli-ohm range), and these MOSFETs do not have mechanical switch contacts that wear out and degrade over time.
6) The SMART module will be available towards the end of next month (September) and the first new Red Wine Audio product that will feature it will be the Signature 30.2... followed soon after by the Signature 70.2.
Signature 70.2 SLA Battery ChargerWe will also be using a special battery charger that has been modified to work flawlessly with the SMART module, and that offers improvements to previous battery chargers that we have used in the past:
1) Output of 24V, 2A.
This will charge 4X faster than the standard charger that was included with the Signature 70.
This new charger will be controlled by the SMART module.
2) This new charger also features a beefy, aluminum XLR plug for a very secure connection to the Signature 70.2 (see rear panel details below).
3) This new charger also features an IEC mains power jack, and universal input voltage so it can work anywhere in the world (100 – 240Vac, 50/60Hz). No special “overseas” charger will be required.
