Hybrid Tube Preamp Buffer - TPB.V1

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tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #60 on: 16 Mar 2017, 08:32 pm »
I just verified via a quick test that you can drop a set of 6CG7's into our buffer as substitutes for the 6H30's with no problem. No surprisingly the gain is a bit off (slightly higher gain with the 6CG7s) but that was just my impression and I didn't confirm this with a scope or dB meter. Sounded real good with the 6CG7's.

Someone asked if 12AU7's would work and the answer is no because the 12AU7's use a different heater circuit. Same for the 12AX.

tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #61 on: 21 Apr 2017, 06:03 pm »
Small preamp buffer.
Amazing sound.
Pretty cat.


WireNut

Re: Hybrid Tube Preamp Buffer
« Reply #62 on: 21 Apr 2017, 10:50 pm »
An update to the tour schedule would be great.
I have 2 Yaqin CD3 tube buffer's that I use in my system.
I'm ready to compare the Tortuga buffer to my Yaqin's.

 
   

tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #63 on: 22 Apr 2017, 01:21 pm »
A couple of additional buffer pics.  :thumb:



WireNut

Re: Hybrid Tube Preamp Buffer
« Reply #64 on: 16 Aug 2017, 11:46 pm »
Which connection "to and from" a Tortuga Tube Buffer makes the most since?

Phono-pre or Dac output  > Tortuga Buffer > Preamp input.

Preamp output  >  Tortuga  Buffer > Active crossover input.

Active Crossover HI-Pass output only > Tortuga Buffer > Amp for Hi-Pass Frequencies.


tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #65 on: 16 Aug 2017, 11:50 pm »
Which connection "to and from" a Tortuga Tube Buffer makes the most since?

Phono-pre or Dac output  > Tortuga Buffer > Preamp input.

Preamp output  >  Tortuga  Buffer > Active crossover input.

Active Crossover HI-Pass output only > Tortuga Buffer > Amp for Hi-Pass Frequencies.


The second.  Preamp > Buffer > ...

WireNut

Re: Hybrid Tube Preamp Buffer
« Reply #66 on: 16 Aug 2017, 11:52 pm »
 :thumb:

Randy

Re: Hybrid Tube Preamp Buffer
« Reply #67 on: 7 Dec 2017, 05:36 am »
Morten,
   Reading this thread leaves me confused (as usual). > symbols confusing.  I have my buffer after the preamp, buffer into the power amp. Is that the best way?

Randy

tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #68 on: 7 Dec 2017, 01:35 pm »
Morten,
   Reading this thread leaves me confused (as usual). > symbols confusing.  I have my buffer after the preamp, buffer into the power amp. Is that the best way?

Randy


Yes. Buffer downstream of attenuator/passive.  It WILL work the other way around but you won't retain all the benefits of the low fixed output impedance of the buffer.

tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #69 on: 11 Feb 2018, 03:22 pm »
Per customer request I recently tested our TPB.V1 Tube Buffer with an ECC88(6922) tube instead of our standard 6H30. Since I only had a single ECC88 available I could only test it in one channel and left the other channel empty/silent. My initial impressions were quite positive. I then put a 6H30 back into the empty slot and ran the buffer with an ECC88 in one side and a 6H30 in the other. Sounded remarkably good and to my surprise the stereo was well balanced indicating that the effective gains were quite similar. I've not compared the specs sheets in detail other than to confirm that the heater current for the ECC88 is substantially lower than the 6H30 (not many 9 pin tubes run as high a heater current as the 6H30's). I've ordered a second ECC88 tube of same make/model and will give the buffer a more thorough listen once I have a pair of ECC88's installed.

While a bit preliminary, I'd say the TPB.V1 buffer is now compatible with not only the 6H30, but also the 6CG7 (the 9 pin version of the 6SN7 octal) and now most likely the ECC88 which also includes the whole 6DJ8 / 6922 / ECC88 / E88CC / CV2492 family tubes.

A tube roller's delight!  :thumb:

who?me?

Re: Hybrid Tube Preamp Buffer
« Reply #70 on: 11 Feb 2018, 06:12 pm »
Sounds great!
Especially that you say it opens up possibilities to roll the 6DJ8 / 6922 / ECC88 / E88CC / CV2492 family of tubes.

But just curious about the life of the different tubes. E.g. if some tubes are hotter, or driven harder than other tubes,
how does that effect the life of the tube (if we buy expensive NOS tubes, I would want to know that I am getting some
decent amount of life out of them).

The ability to choose a +3 or +6 dB gain is also so useful. Just thinking that a -3dB gain would also be equally beneficial
for the "loudness wars" recordings.

tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #71 on: 12 Feb 2018, 02:37 pm »
But just curious about the life of the different tubes. E.g. if some tubes are hotter, or driven harder than other tubes,
how does that effect the life of the tube (if we buy expensive NOS tubes, I would want to know that I am getting some
decent amount of life out of them).

In normal preamp/amp applications most tubes run at plate voltages in the range 100-450 volts depending on the spec of the tube. The tubes in our buffer are run at a modest 30 volts with commensurate low current since the tube is used as an input stage with default 0 dB gain. One could argue that at such a low plate voltage/current the life of most any tube in such an application is indefinite. Of course then there's the tube heaters which run at 6.3 volts DC but that's the same for all these tubes in any application and running them in our buffer isn't going to be better/worse in terms of their life as far as heater longevity is concerned. In short, our buffer does not run hot nor does it drive the tubes hard. It also uses a switch mode DC-DC regulator for the heater current so that internally the buffer power supply generates very little heat compared to using most any linear regulator. In my view this hardware, including the tubes, will last a very very long time.

Quote
The ability to choose a +3 or +6 dB gain is also so useful. Just thinking that a -3dB gain would also be equally beneficial
for the "loudness wars" recordings.

-3dB etc. is the job of your preamp/attenuator upstream of the buffer.  :thumb:

Randy

Re: Hybrid Tube Preamp Buffer
« Reply #72 on: 8 Apr 2018, 01:17 am »
I just changed out the stock tube with "Gold Lion" E88CC. A nice bump up in the sonics. Cleaner, clearer, richer, more transparent even before they warmed up. Impressive.  An already great product takes a step up. Way more than I expected, if I expected anything, skeptic that I am.

I went for all the alternatives they offer, triode, high gain,balanced, low noise and microphonics. I really don't know what most of that means, but it sounded good, and didn't add that much to the basic cost. Maybe Morten can offer some comments.
« Last Edit: 1 May 2018, 02:17 pm by Randy »

sfox7076

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Re: Hybrid Tube Preamp Buffer
« Reply #73 on: 8 Apr 2018, 11:26 am »
I am interested in how a tube stays linear with such a low plate voltage. 

tortugaranger

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Re: Hybrid Tube Preamp Buffer
« Reply #74 on: 8 Apr 2018, 04:11 pm »
I am interested in how a tube stays linear with such a low plate voltage.


In a buffer application you aren't asking the tube for any voltage gain so you don't need much voltage swing from the output. You are basically just tracking the linestage input which is a few volts at most. You're also operating with grid input voltage at or near 0 volts with no input coupling cap. Down in that corner near zero Vgs and low plate voltage you can actually get fairly linear operation. It can work surprisingly well.