Torpedo III Build Thread
Feb 9, 2018 at 5:12 PM Post #304 of 322
Getting ready to join the T3 club soon. Very excited. It will be fed by my CD Player/Gumby. Headphones are Beyerdynamic T90.

At 250ohm (my T90s), I am reading the 12AZ7 tubes are best. So I am on the hunt for a pair of GE's.
 
Feb 10, 2018 at 8:27 AM Post #305 of 322
Getting ready to join the T3 club soon. Very excited. It will be fed by my CD Player/Gumby. Headphones are Beyerdynamic T90.

At 250ohm (my T90s), I am reading the 12AZ7 tubes are best. So I am on the hunt for a pair of GE's.
Actually, the latest info on tubes came to the conclusion that the Mullard 12AT7WA (CV4024) was best:
https://www.ebay.com/itm/12AT7WA-CV...211738?hash=item4836deba9a:g:WQQAAOSwHnFVrhHZ

Their response is as good as the 12AZ7s. Plus, they have the best sound stage of most tubes that have been tried in the T3. Downside? They're expensive. Also, while the ebay seller referenced above seems to have the lowest reliable price, his "matching" is really a manufacture-lot matching, not tube output. Thankfully, the Mullards are very high quality and seem to be closely matched in output anyway. You'll probably find a pair that match well if you purchase a quad and your odds are pretty good even by purchasing a pair.

The 12AZ7s are outstanding for the price, but they are hard on the amp. The heater current runs much higher than the 12AY7 or 12AT7 (including the Mullard 4024 above). So, the amp will run pretty hot. I would not recommend leaving it on for extended periods with the 12AZ7s.
 
Aug 10, 2023 at 8:28 AM Post #310 of 322
I don't know if this is allowed anymore, but I'm retired, trying to clear out a lot of stuff, so will give it a shot anyway. :wink:

There are several Torpedoes available now at Beezar Audio, among a couple of Millett Maxes, some nice Senn cabling plugs, and even a few NOS Black Gate NX capacitors I found in the bottom of a file cabinet drawer.

I'm referring to the Torpedoes as STEALTH Torpedoes, because they are four (4) tested prototypes whose bare, populated PCBs have been in storage (AC-conditioned Beezar space) for almost a decade. I purchased new, custom-machined, black-anodized Context Engineering enclosures with no labeling whatsoever (hence, "STEALTH") and cased them up as fully functioning headphone amplifiers. STEALTH Torpedo 1 is the first production Torpedo 1 prototype, STEALTH Torpedo 1B is a production prototype Torpedo 1 using a toroid power transformer, STEALTH Torpedo 2 is the second of only two prototypes of the Torpedo 2 using 6922 tubes. Finally, STEALTH Torpedo 3 is the very first and only T3 prototype. Except for the toroid PT in the STEALTH Torpedo 2, all of these amplifiers are true high-voltage output transformer-coupled tuber amplifiers using Edcor PTs and OTs. The STEALTH Torpedo 3 uses a combination of electrolytic and film bypasses in the interstage capacitor section, but uses the 12AT7 tube basis and DSHA buffer (tube hybrid) that the production T3s used.

20230725_091722.jpg
 
Dec 7, 2023 at 10:06 PM Post #311 of 322
For what it is worth, and this is obviously super late, but I picked up the 1B. Can't believe these have been available for so long given the builder reputation and value here. Curious to see how the SumR toroid holds up, rocky past but I am still excited to give it a good home. That T2 looks awesome too, someone would be lucky to have it.
 
Dec 8, 2023 at 2:12 PM Post #312 of 322
For what it is worth, and this is obviously super late, but I picked up the 1B. Can't believe these have been available for so long given the builder reputation and value here. Curious to see how the SumR toroid holds up, rocky past but I am still excited to give it a good home. That T2 looks awesome too, someone would be lucky to have it.
I'm glad you made the investment. These are great amps for the money and the design is fun too.
 
Dec 10, 2023 at 4:54 PM Post #315 of 322
Wow was there? Cinemag and Jensen are the only ones that make them now that I know of. I miss MQ.

I asked Google looks like Cinemag

https://ecp-consolidated-production...afeed-transformers-pair-/5?cs=true&cst=custom


Solid high nickel core output transformers for headphone amplifiers. These transformers are made for us by Cinemag and feature a 10K Ohm primary (~120H of inductance) and a 300 Ohm secondary with a 32 Ohm tap. They were designed for the Torpedo 3 project, but they will also work with the Torpedo 1 and L2 PCBs and various other DIY projects. EI-625 cores, and pin compatible with the Edcor PCW10K-7K/300-32 OPTs (https://www.edcorusa.com/pcw10k-7k_300-32).

* Note, these transformers are not designed to block high DC voltages. They must be AC (capacitor) coupled to a high voltage circuit.
 

Users who are viewing this thread

Back
Top