Friday, September 27, 2013

Glamour Shot: EXO-046s

This EXO-046 is one of a pair. Built with nickel lams and housed in steel channel frames, they're sleek and sexy.

Primary impedance 5000 ohms. Secondary impedance 16 ohms.  MOL 2++ watts.  Parafeed. Most often used with the 45 tube and a  BCP-15 plate choke. Great for use with 16 ohm single full range drivers.

Want to own a pair? Email us at acrosound [at] aol [dot] com.

Monday, September 23, 2013

Glamour Shot: FS-030

This FS-030 is one of a pair built with special covers. We love the contrast of the pale green with the black painted lams. Don't you?

For complete specs

Interested in owning your own pair? Email us at acrosound [at] aol [dot] com.

Thursday, September 19, 2013

Build and Let Build

"C'mon, this is a hobby -- you enjoy it your way, and I'll enjoy it mine, and if aesthetics and industrial design happen to be important to me, who cares? Listen and let listen. Build and let build."

So wrote member Jim R. of the Bottlehead forum on a post a while ago about polishing brass bell ends. While transformers and DIY audio are our business, we hope our customers enjoy themselves when using our products.

And he brings up an interesting question: What's important to you in audio transformer design? (Speaking of aesthetics, don't you love the above picture of our MQ-470?)

Monday, September 16, 2013

From the Bottlehead Forum: About the BCP-15

MagneQuest BCP-15
The BCP-15 was an original Freed design.  It was originally spec'd at 50 madc and 40 Henries. We built many of these to the original specs. These would tend to have only the BCP-15 marked on them.  

Later... realizing that most people who were purchasing these plate chokes were using them with the type 45 tube which runs moreso typically at 35 to 40 mils of plate current. After careful analysis of the original design we were able to regap the unit and optimize it for use with the 45 tube at the ballpark 40 mils instead of 50 mils of plate current. With the smaller airgap, we picked up more L (50 henries).

Once we offered the second choice -- 40 mils at 50 henries or 50 mils at 40 henries -- I've tried to be consistent (bearing in mind the existence of human frailty) and mark the coils that were gapped for 40 mils. Often times (but not always) this demarcation might be written on the back side of the coil.  

The 50 mil coils may or may not have the marking -- if it's not marked--- again allowing for the occasional human error -- it is most likely gapped for 50 mils. 

This description comes from the Bottlehead forum for "All things MagneQuest." Check out the thread here.

Friday, September 13, 2013

Have You Met Our Robin Hood Series?

The Robin Hoods' series consists of three single-ended air-gapped output transformers. The aim of the series is two- fold. First is to offer a transformer for folks who are bi-amping and don't need the huge inductances and AC power capabilities of say our legendary FS-030 single ended  output transformer.

The second aim/goal is to make these the best VALUE output transformers available in the marketplace. The "Robin Hood" series is named in honor of the man who took from the rich, as in the richness of MagneQuest's proven designs, to give to the poor, as in DIY lovers who crave high value without sacrificing top quality.

The primary copper circuit is smartly crafted to keep resistive losses at a minimum (the dcr is approx. 185 ohms). The copper losses from the full secondary and the full primary are equal in magnitude. The primary inductance is carefully designed to fully support the published low frequency extension of each model at the maximum stated power level. The total (AC and DC combined) magnetic flux density is kept BELOW 16kg in each model offered in this series. Therefore, these will not saturate or "run out of iron" when used within their published specs.

Simply put, these are expertly designed transformers with an emphasis on sound quality. We didn't skimp in the goodies department. All of the RH series are made with pure Teflon insulation on the inside. All solder connections are made with silver bearing solders. All units are housed in channel frames with easy to solder to terminals. They are as easy to install as they are musical in their sound delivery.

Currently, three different models are available in the following configurations. All have 5K primary impedances.

Here are the specs for the RH-40, RH-60, and RH-80 which cost $125 each.

Sunday, September 08, 2013

Power Transformers: R-080, R-160, R-196

Model R-080 is 275-0-275 at 20 madc and has a 6.3vct winding at 2Arms. This unit was designed by Peerless as a special low flux density preamp power trans. It is way conservative in design. 

Model R-160 is 275-0-275 at 40 madc and has a 6.3vct winding at 2 Arms and a 5 volt winding at 2 Arms. 

Model R-196 is 300-0-300 at 50 madc and has a 6.3vct winding at 2.5 Arms and a 5 volt winding at 2 Arms. 

All are laydown transformers and are supplied with solder lugs (terminals).