[Elizabeth]

I guess this is really for James Tanner:
I tried to find  the post with this info mentioned.. no luck.
The post had a mention that when ordered, the 7B-SST2 could be ordered either in series configuration, or parallel configuration. (Which one being standard, which I also do not know)
Please, What is the reason, or advantages of each configuration?
(I am most interested in dealing with a 4 ohm load, having more amperage, than voltage) Also ,does one have more distortion.. or whatever..

Also do the 28B-SST2 also have this option?

This has been bugging me, and so I finally am posting about it.

Also, what would one have to tell the dealer, to order the alternate configuration. (and is there ANY markings on the item spelling out  it is made with the alternate configuration?)

Thanks James. 

[James Tanner]

I guess this is really for James Tanner:
I tried to find  the post with this info mentioned.. no luck.
The post had a mention that when ordered, the 7B-SST2 could be ordered either in series configuration, or parallel configuration. (Which one being standard, which I also do not know)
Please, What is the reason, or advantages of each configuration?
(I am most interested in dealing with a 4 ohm load, having more amperage, than voltage) Also ,does one have more distortion.. or whatever..

Also do the 28B-SST2 also have this option?

This has been bugging me, and so I finally am posting about it.

Also, what would one have to tell the dealer, to order the alternate configuration. (and is there ANY markings on the item spelling out  it is made with the alternate configuration?)

Thanks James. 

Hi Elizabeth - Vegas 6:30 AM

The previous versions of the 7B's (before SST2) had the Series / Parallel option.  The idea was that very low impedance loads (1-2 Ohms) sounded better when driven with more Current (Parallel Mode) and less Voltage (Series Mode) - impedances in the 3-8 Ohm range were better with more Voltage (Series Mode). So we offered a version of the amps with a switch to go between the Series and Parallel modes.  Then we decided to get the switch out of the way and offered different versions (SST) to order - indicated on the rear with a silk screen. 

When we went to the SST2 designed 7B we found that the larger transformers had very little difficulty with the lower impedances below 3 ohms unless the 1 to 2 ohms where over a very large range of frequencies. At that point we felt offering a second version (Parallel Version) really was not necessary given 99.9% of the speakers out there are higher in imedance and require much more voltage swing than current swing. 

So Magnepans being a Planar Dynamic speaker needs lots of voltage swing (contrary to what most people think) - true the ribbon has a lower impedance than most speakers but the impedance is very 'resistive' as opposed to 'reactive' (EX: electrostatic speaker).  The other problem is you use the Parallel version on an 8 ohm speaker a 7B would give you about 180 watts instead of 600.

So it really comes down to what speaker you are using and given that the vast majority of speakers fall between 3-8 ohms the standard Series 7B SST2 is the better choice.  We will do a custom version of the 7B SST2 in Parallel if a customer wants but it would be a very rare circumstance indeed.

Hope this helps

james

PS - no 28B Parallel version for reasons above.

[Diamond Dog]

You should really go to bed soon, James. Vegas or not...

D.D.