[FallenAngel]

Well, that didn't take long!
 
I hooked up my testing system and checked through everything.
 
With some sensitive AKG K518 (32 Ohm, 115dB SPL/V), the background is dead black. With the UE700, I get a bit of hiss around 80% volume at which the volume is beyond ear-splitting, it's deafening. I seem to only hear something with those IEMs off this amp.
 
Look like the DAC I use everyday has enough noise in it that these IEMs can detect. Well, no surprise as it's a balanced DAC with a discrete output stage pushing 4V balanced... Yeah, it's a bit much...With my normal listening setup of Buffalo 3 - Legato - Balaned Dynalo - HD650, there's nothing in the background. Who knew you could connect a pair of IEMs to this system, and slap the man who did it!
 
No worries guys, the Torpedo 3 is about as silent as my system could ever be.
 
Don't mean to make you worry Tom, sorry about that.

 

[tomb]

  Well, that didn't take long!
 
I hooked up my testing system and checked through everything.
 
With some sensitive AKG K518 (32 Ohm, 115dB SPL/V), the background is dead black. With the UE700, I get a bit of hiss around 80% volume at which the volume is beyond ear-splitting, it's deafening. I seem to only hear something with those IEMs off this amp.
 
Look like the DAC I use everyday has enough noise in it that these IEMs can detect. Well, no surprise as it's a balanced DAC with a discrete output stage pushing 4V balanced... Yeah, it's a bit much...With my normal listening setup of Buffalo 3 - Legato - Balaned Dynalo - HD650, there's nothing in the background. Who knew you could connect a pair of IEMs to this system, and slap the man who did it!
 
No worries guys, the Torpedo 3 is about as silent as my system could ever be.
 
Don't mean to make you worry Tom, sorry about that.

 
Great!  No worries - good to know things are fine.  I hope people get to enjoy the T3 at your meet and good luck!

 

[FallenAngel]

Great!  No worries - good to know things are fine.  I hope people get to enjoy the T3 at your meet and good luck!

 
Shhh! Nobody knows that I'm bringing this! I think this will be the first T3 anybody has ever heard in Toronto

 

[JamieMcC]

Hi Tomb any idea when the cinemags for the T3 will be back in stock and what is the availability of the tail CCS?
 
tia
 
Cheers
 
Jamie

 

[tomb]

I believe Dsavitsk is hoping by the end of the month.

 

[NuClear235]

I found the same construction philosophy headphone amp
http://www.6moons.com/audioreviews/yamamoto4/ha02.html
 
I dont know its sound. I just foud it on web...
Ilike using C-core power tranformer. Dont it make possible shorter construction ?

 

[tomb]

I found the same construction philosophy headphone amp
http://www.6moons.com/audioreviews/yamamoto4/ha02.html

I dont know its sound. I just foud it on web...
Ilike using C-core power tranformer. Dont it make possible shorter construction ?

Same construction philosophy? There is nothing similar except for saying that both use tubes. For that matter, there was no reference to DIY, either.

 

[Misterrogers]

Heh. Yea, I was scratching my head on that one too.

 

[tomb]

Torpedo III kits (and a couple assembled) are back in stock at beezar.com with Cinemag output transformers!

 

[audiojun]

How hard is the torpedo III kit to assemble? The only diy experience I have was building the crack and that was about medium difficulty to me.

 

[tomb]

How hard is the torpedo III kit to assemble? The only diy experience I have was building the crack and that was about medium difficulty to me.

 
It's ridiculously simple compared to a Bottlehead.  There is no wiring whatsoever except for the small volume pot ground wire and a safety ground wire to the case back at the power transformer.  Everything, literally everything - is all on the PCB.  There are some tricks on the hardware, which many people try to shortcut (not recommended), but if you are good with screws, washers, lock washers and nuts*, there's nothing to worry about.
 
 
* It's constantly amazing to me how many people have trouble with simple screw-washer-lock-washer-nut assemblies, but there you go.  I've had people send me their amps for repair and more than half the hardware was missing and yet, I supply every bit of it with the kits.  Unbelievable.

 

[audiojun]

Thanks for the info I am probably going to order this soon.
 
I have a few more questions: What is the output impedance of the amp on low z and on high z? Also is this a push-pull amplifier? (The word differential in the amp name sounds like push-pull).

 

[tomb]

  Thanks for the info I am probably going to order this soon.
 
I have a few more questions: What is the output impedance of the amp on low z and on high z? Also is this a push-pull amplifier? (The word differential in the amp name sounds like push-pull).

You're going to have to ask Dsavitsk about output impedance.  I don't think it has the same meaning that everyone uses when output transformers are involved.  The output transformers can almost be wound to any output impedance desired.  So, the choice is a conscious design decision.  The output transformers themselves are wound for either 300 ohm output matching (high-Z) or 32 ohm output matching (low-Z).  I'm not exactly sure what that means for the overall output impedance for the amp, but the idea is that the separate windings sort of make impedance values of the headphones moot.  The amp produces essentially the same power at 300 ohms that it does at 32 ohms.
 
As for differential and push-pull, yes - they are similar.  In the T3, the tubes actually perform the phase split/inversion by virtue of a long-tail-pair configuration.  So, the amp is differential from the point of the tubes' output all the way to the output transformers.  Some people call that balanced and ask why there aren't balanced connectors on the input an output.  The reason being is that the T3 was not designed to take advantage of balanced connections.  Rather, it uses the differential internal circuitry to lower common mode distortion/noise.
 
With a 12AY7 tube, I've measured distortion from 20Hz-20kHz as low as 0.014% THD at 32 ohms and as low as 0.0062% at 300 ohms.  Using 12AZ7 tubes, I've measured distortion in the T3 as low as 0.0031% THD at 300 ohms.  This is simply superlative for a tube ampilifer and pretty d*mn good for solid-state, too.

 

[dsavitsk]

Push-pull is a large catchall that is not very descriptive. Yes, it is push-pull, but this does not mean that it is very closely related to many other designs that can also be described as push-pull. It is a differential circuit, which is a better description here.

The output impedance is very low and is basically just due to the transformers windings. The output portion of the circuit, which is a differential darlington emitter follower, has a Z out of just a few ohms. When transformed by the transformer it is basically 0. The copper just adds some series resistance - under 10 Ohms on low and around 20 Ohms on high IIRC.

How that relates to the 32 Ohm and 300 Ohm rating of the transformer has to do with the transformer's primary inductance, winding ratio, and the resulting impedance at a particular frequency (20Hz here). In both cases, the rated load reflects a 7K Ohm impedance to the output circuitry.

 

[audiojun]

Thanks for all the info guys! Happy Easter!
 
@tomb
I just placed my order #2930. I went all out with the Cap upgrade and Cinemag Transformers. Give me some cherry picked and matched parts please!
 
@dsavitsk
My dad is a little against push-pull topography but this "differential" amp is probably something special. I hope to prove him wrong with the Torpedo III.