This is a review and detailed measurements of the Tortuga TPB.V1 Balanced Tube Preamp Buffer with various set of tubes. It is on kind loan from a member and costs US $1,695 with "Matched Pair Electro-Harmonix 6H30Pi Gold triode tubes."
There is not a whole lot to look at here other than the two tubes sticking out the back:
There is an internal gain setting which I left alone meaning the unit runs as a buffer (gain of 1). Architecture is tube front-end but back-end is transistor based (I assume to keep impedance low). There is some kind of protection and monitoring circuit that blinks until the tubes have stabilized.
Like the balanced configuration which is rare in tube products:
The transformer bolt had come loose and I could feel it by shaking it. Tried to tighten it from outside but keeps turning. Likely need to hold the nut inside to keep it from turning.
There are no safety marks on the amplifier.
Tortuga TPB.V1 With Electro-Harmonix 6H30Pi Tubes Measurements
I installed the pair of tube supplied with the amplifier and fired up the dashboard:
I always think something is broken in my instrumentation until I realize this is a tube amp that is made to be a distortion generator (intentionally or not). These are stunningly high levels of distortion but we are driving it at full level. I will show lower levels in a bit. Note that the spectrum shows the dominant component is third harmonic, not second. So even if we assume the common myth that 2nd harmonic is good for you, this box won't deliver that.
Let's sweep the level and see how the distortion varies:
The tubes don't seem very "matched to me." That aside, at very low input/output levels, distortion+noise goes down to -60 to -70 dB. In my experience, typical audiophile can't perceive such levels of distortion so it is unlikely any effect you think you are hearing is due to this box.
SNR is better than I expected:
Frequency response is excellent:
As is crosstalk:
What is not so excellent is IMD distortion+noise:
Ditto for THD+N vs frequency which is off the chart almost:
Fortunately it is horrible at all frequencies so there is a silver lining there!
Tube Rolling Measurements
I was supplied with three other sets of tubes so let's look at how they do starting with Electro-Harmonix 6922:
Man, this makes the supplied tubes look hi-fi! It has so much distortion that you don't need to measure them: just look at how deformed the sine wave has become! People say "trust your ears." No, I say trust your eyes!!! This is horrid. Notice that gain has become negative as well. But maybe these tubes are broken, or the circuit is not optimized for them.
Another set that was supplied is from Russian Reflector factor, the 6H30P-DR:
We get the same performance as the supplied tubes which I guess is "good."
The wheels fall off again when we switch to Mullard CV2493 tubes:
The owner tells me these are highest spec'ed tubes of this kind. If they are, something is really, really wrong here.
Conclusions
I am sure everyone who bought these preamps had different ideas than what these measurements show. They thought they were getting second harmonic "tube sound" but instead are getting 3rd harmonic. And with half the tubes tested, the product is just outright broken with severe distortion. I don't care if you want to believe in tube products. Ask for measurements so that you know you are getting what you imagining.
No, I am not going to recommend the Tortuga TPB.V1 Balanced Tube Preamp Buffer. Don't screw up your system with stuff like this. Spend the money on good music, food and fun with the family instead.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
There is not a whole lot to look at here other than the two tubes sticking out the back:
There is an internal gain setting which I left alone meaning the unit runs as a buffer (gain of 1). Architecture is tube front-end but back-end is transistor based (I assume to keep impedance low). There is some kind of protection and monitoring circuit that blinks until the tubes have stabilized.
Like the balanced configuration which is rare in tube products:
The transformer bolt had come loose and I could feel it by shaking it. Tried to tighten it from outside but keeps turning. Likely need to hold the nut inside to keep it from turning.
There are no safety marks on the amplifier.
Tortuga TPB.V1 With Electro-Harmonix 6H30Pi Tubes Measurements
I installed the pair of tube supplied with the amplifier and fired up the dashboard:
I always think something is broken in my instrumentation until I realize this is a tube amp that is made to be a distortion generator (intentionally or not). These are stunningly high levels of distortion but we are driving it at full level. I will show lower levels in a bit. Note that the spectrum shows the dominant component is third harmonic, not second. So even if we assume the common myth that 2nd harmonic is good for you, this box won't deliver that.
Let's sweep the level and see how the distortion varies:
The tubes don't seem very "matched to me." That aside, at very low input/output levels, distortion+noise goes down to -60 to -70 dB. In my experience, typical audiophile can't perceive such levels of distortion so it is unlikely any effect you think you are hearing is due to this box.
SNR is better than I expected:
Frequency response is excellent:
As is crosstalk:
What is not so excellent is IMD distortion+noise:
Ditto for THD+N vs frequency which is off the chart almost:
Fortunately it is horrible at all frequencies so there is a silver lining there!
Tube Rolling Measurements
I was supplied with three other sets of tubes so let's look at how they do starting with Electro-Harmonix 6922:
Man, this makes the supplied tubes look hi-fi! It has so much distortion that you don't need to measure them: just look at how deformed the sine wave has become! People say "trust your ears." No, I say trust your eyes!!! This is horrid. Notice that gain has become negative as well. But maybe these tubes are broken, or the circuit is not optimized for them.
Another set that was supplied is from Russian Reflector factor, the 6H30P-DR:
We get the same performance as the supplied tubes which I guess is "good."
The wheels fall off again when we switch to Mullard CV2493 tubes:
The owner tells me these are highest spec'ed tubes of this kind. If they are, something is really, really wrong here.
Conclusions
I am sure everyone who bought these preamps had different ideas than what these measurements show. They thought they were getting second harmonic "tube sound" but instead are getting 3rd harmonic. And with half the tubes tested, the product is just outright broken with severe distortion. I don't care if you want to believe in tube products. Ask for measurements so that you know you are getting what you imagining.
No, I am not going to recommend the Tortuga TPB.V1 Balanced Tube Preamp Buffer. Don't screw up your system with stuff like this. Spend the money on good music, food and fun with the family instead.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/