Hey Guys,
I wanted to go into greater detail on the actual product that has brought Danny and I together and also share with you some thoughts we have on what might be possible in the future via this combined effort from GR Research and HA. In working with Danny we have come to realize just what an amazing resource we have found.
I like to be very open about our strengths and also our weak areas here at Hawthorne Audio. We are very good as developing specific tools for the task at hand. That is sort of my thing if you will. I like to purpose build tools or in this case drivers to do one exact task and do that one exact thing very, very well. The challenge I have is that I am not well educated with regard driver engineering or crossover design. Truth is that it’s not an area that I excel at and so I make up very extensive wish lists of sonic attributes and performance goals and challenge professionals to take these lists and see how many boxes they can check off. Finding someone that not only enjoys designing filter networks but is acknowledged as one of the leaders in this field has opened up many new and exciting doors for us and given us a chance to work with a true professional. I think up these crazy ideas and the Pros like Danny help us turn these dreams into reality.
Our first collaborative project was to evaluate this new Model 700 AMT and see if it could be matched up with one of our existing mid woofers. In so doing we also wanted to look at what other potential projects this driver could excel in but also think about what might be possible if we made up a new wish list and developed additional drivers specifically for some pet projects we both envisioned might be fun to offer in the future.
The Model 700 AMT is our first DIY AMT driver in that unlike it’s big brother the Model 500 AMT we are offering the 700 for sale to DIY for use in their own projects but also to serve as a potential upgrade path for those folks currently using our coaxials. Guys that might want to upgrade just the high end section of their coaxials yet still preserve the high sensitivity and dipole projection of their OB coaxials. Here is the driver element and purpose built wave guide:
Danny ran the numbers on this new AMT driver and also the first mid woofer candidate we wanted to evaluate for possible use with it. This mid woofer is our long standing 15” Sterling Silver Iris Mid driver previously used in the coaxial format along with Radian compression tweeters. Nice OB coaxial offering that we have had some success with!
Here is the test rig mockup I sent to Danny
Large and Dog Butt ugly but easily reconfigurable so that we can run lots of experiments using different driver combinations.
All our drivers carry the 'Silver Iris' branding somewhere in their official naming. This model 700 Is actually officially called our Silver Iris Model 700 AMT for example. Too long to keep writing out so we shorten everything as best we can.
This 15” Mid woofer excels in a certain frequency band and it, like all drivers has compromised areas of operation. Areas that we would like to not have the driver attempting to cover. Ideally we would like to use it only in it’s most optimal range of operation and have this AMT driver step in and do what it does best. Proper tool for the task at hand thinking. Danny was able to quickly access exactly where each driver should be used and set about to stitch the two drivers together seamlessly to act as one.
As luck, fate or chance might have it, both drivers really complimented each other. They both filled in the intrinsic weaknesses of each other so beautifully that the result was a near perfectly flat response. This by itself is always nice to see but we also noticed that they both shared an almost perfect sensitivity match.
Other complimentary features such as similarly high displacements, overall musicality, resolution, refinement and presence were like icing on a cake.
Take a look at this combined frequency response
When Danny first sent me this I hadn’t looked closely at the scale of resolution and asked if this response was ok? Looked sort of
wavy to me?
He then shared the following
That's not wavy. That's super flat. The scaling is just zoomed in. All the way to 2.8kHz it is +/-.875db. The whole thing is +/-2.25db from end to end
After a brief period of this
my reaction quickly turned to this
So, these two drivers liked each other and work very well together. What’s next?
The physical size of the model 700 as well as it’s frequency response is ideal for use with these large format mid woofers but might be less than ideal for use with some smaller drivers in some other projects we wanted to explore. Danny asked if we had any shorter AMT designs in the works and in fact we had one on a back burner. The Model 900 was shorter and was close to being a working prototype. Previously we had put all our attention on these very broad band AMT drivers for obvious reasons.
With a shorter AMT we can use it with some 8” or possibly some 6.5” mids both in OB but also in smaller sealed enclosures. (our AMT drivers can be configured to be used as either dipole or monopole). This opens up the possibility of using them in some of GR's previously issued kits as well as opens up the door to new speaker designs we both have been wanting to dig into.
The Model 900 is past all of it’s preliminary steps towards becoming a real product and so far everything suggests that it will share a very similar sonic signature to it’s bigger brothers. The only thing that changes is the physical size, extension and displacement. This driver will also come with it’s own purpose built wave guide just like all the others. We intend to sell these Model 900 AMT drivers as stand alone offerings so that folks may use them in their DIY projects but also work them into some fully optimized kits and finished speakers that are marketed by both GR Research and Hawthorne Audio.
Stayed tuned for updates. I hope to get the first sample of the 900 to Danny very soon so that he can do that voodo that he do.
Cheers,
Darrel
