Hybrid Tube Preamp Buffer

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tortugaranger

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Re: Hybrid Tube Buffer
« Reply #20 on: 28 Nov 2016, 05:11 pm »
Any "ballpark" figures for input/output impedance?

The input impedance is somewhat arbitrary and it set by an input stage resistor. It will likely be at least 47k and may be as high as 100k. That's a fine tuning decision that we'll test in the final prototype board which we will have in-house by Friday/Saturday this week. Although the designation "final prototype board" tends to be used prematurely we are really close to finalizing this puppy.

The output impedance is approximately 20 ohms which is inherent in the output stage stage design and is not likely to change.  That is a modeled value and not a test value but is very much in the ballpark of what it will really be.

33na3rd

Re: Hybrid Tube Buffer
« Reply #21 on: 28 Nov 2016, 05:44 pm »
The input impedance is somewhat arbitrary and it set by an input stage resistor. It will likely be at least 47k and may be as high as 100k. That's a fine tuning decision that we'll test in the final prototype board which we will have in-house by Friday/Saturday this week. Although the designation "final prototype board" tends to be used prematurely we are really close to finalizing this puppy.

The output impedance is approximately 20 ohms which is inherent in the output stage stage design and is not likely to change.  That is a modeled value and not a test value but is very much in the ballpark of what it will really be.

That's great news, thank you!

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #22 on: 1 Dec 2016, 12:21 am »
The latest prototype board of our hybrid tube buffer arrives in the mail tomorrow. I'll be stuffing that board ASAP and firing it up over the weekend to see where things stand. This is the 3rd prototype revision of this particular design so I have high hopes that everything will fall into place.

Assuming this prototype performs well, we'll start accepting pre-orders (no upfront payment) in December with release scheduled for later in January. 

I'll update this topic as soon as I've had some run time on the latest prototype. Getting very close!!!  :thumb:

TrungT

Re: Hybrid Tube Buffer
« Reply #23 on: 1 Dec 2016, 03:25 am »
 :thumb: Can't wait

rlee8394

Re: Hybrid Tube Buffer
« Reply #24 on: 1 Dec 2016, 05:31 am »
Try using the 6N6P.

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #25 on: 1 Dec 2016, 10:07 am »
Try using the 6N6P.

I've not tried the 6N6P but no doubt there will be opportunity for tube rolling with our tube buffer. The most common constraint in trying alternative tubes is that the existing heater power supply doesn't have sufficient current capacity. That will not be the case with our tube buffer since the 6H30 is already a high current tube. It looks like the 6N6P is slightly higher current than the 6H30 but that won't be a problem. Gain may get all wonky with other tubes but if necessary this can be overcome changing out a resistor or two.

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #26 on: 1 Dec 2016, 03:14 pm »
We just published our latest article on the website entitled "Is An Audio Buffer Right For You?"

Yes, I know that's a corny title but the purpose of the article is to educate audio enthusiasts who aren't technical experts on what a buffer does. where a buffer fits in the audio signal chain, and why you might benefit from using a buffer.

Here is the article:  http://www.tortugaaudio.com/is-an-audio-buffer-right-for-you/

Look forward to any comments or suggestions.

Cheers,
Morten

konut

Re: Hybrid Tube Buffer
« Reply #27 on: 1 Dec 2016, 11:19 pm »
Any ballpark estimate on how much this is going to cost?

Any thoughts on a tour?

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #28 on: 2 Dec 2016, 12:36 am »
Any ballpark estimate on how much this is going to cost?

Any thoughts on a tour?


Still a few days away from finalizing pricing. Need to confirm latest prototype design is good to go which I should know by next week.


There will definitely be a tour!!  :D

konut

Re: Hybrid Tube Buffer
« Reply #29 on: 2 Dec 2016, 01:13 am »

There will definitely be a tour!!  :D

Sign me up!

OzarkTom

Re: Hybrid Tube Buffer
« Reply #30 on: 2 Dec 2016, 04:25 am »

TJHUB

Re: Hybrid Tube Buffer
« Reply #31 on: 2 Dec 2016, 10:51 pm »

There will definitely be a tour!!  :D

Don't leave me out.  Sign me up too!

33na3rd

Re: Hybrid Tube Buffer
« Reply #32 on: 2 Dec 2016, 10:57 pm »


There will definitely be a tour!!  :D

If we are starting the list now, please sign me up too!

glynnw

Re: Hybrid Tube Buffer
« Reply #33 on: 3 Dec 2016, 03:09 am »
RE: Tour  -  Please count me in. Glynn Wilson

rklein

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Re: Hybrid Tube Buffer
« Reply #34 on: 3 Dec 2016, 05:49 am »
I would absolutely want to be included on this tour.  Still looking for a pre and this just might be the ticket!

Regards,

Randy

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #35 on: 3 Dec 2016, 08:08 pm »
Holy crap this buffer sounds good!!!  :o

Have it connected to the output of an LDR3.V2 Passive. Amazing dynamics. Really has some serious punch. All the great qualities of the LDR attenuator but more muscular. I was running one channel through the buffer and the other purely passive and then was switching between left/right (buffered/unfbuffered channels. The unbuffered passive is very smooth and musical - polite! The buffered version is way more in-your-face!  The buffer is set up with unity gain so same volume both  channels. Noticed that listening at lower volume levels is more satisfying with the buffer compared to the unbuffered passive.

Still not ready for prime time though. The heater power supply design needs more refinement to get it dead quiet. Heaters draw close to 1.7 amps. Also want to be able to use even slightly more power hungry tubes that need almost 2 amps for a pair of heaters. That means putting everything on a single board is out. May end up with a toroidal transformer with cover on the top of the enclosure. We'll see. Divide and conquer!

For those interested in a tour, I will set up a separate tube buffer tour topic to plan and manage that.
« Last Edit: 3 Dec 2016, 09:22 pm by tortugaranger »

kernelbob

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Re: Hybrid Tube Buffer
« Reply #36 on: 3 Dec 2016, 10:19 pm »
Hi Morten,

If there's a balanced version of the tube buffer in the works, I definitely want to try it.  As you know, my biamplified system using an LDRxB-V2 (with absolute phase switching) and an LDR1B-V2 to trim the level match the bass amp is a prime candidate for a buffer.

I have to say, though, that converting both of my Tortugas to battery power took my system to another higher level altogether and I'm curious how the active power supply of a Tortuga tube buffer would affect that change.

Best,
Robert

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #37 on: 3 Dec 2016, 10:48 pm »
Hi Morten,

If there's a balanced version of the tube buffer in the works, I definitely want to try it.  As you know, my biamplified system using an LDRxB-V2 (with absolute phase switching) and an LDR1B-V2 to trim the level match the bass amp is a prime candidate for a buffer.

I have to say, though, that converting both of my Tortugas to battery power took my system to another higher level altogether and I'm curious how the active power supply of a Tortuga tube buffer would affect that change.

Best,
Robert

It's being designed so that it can be configured as either SE or balanced. There's a triode for each channel. For SE only one side (+) of each triode is used. For balanced both sides (+ & - ) are used.   :thumb:

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #38 on: 8 Dec 2016, 04:55 pm »
A quick development status update. Space constraints forced us to split the single buffer board into 2 separate boards: 1) power supply board, and;  2) tube board. The PS board sits in the lowermost slot near front of the enclosure and the tube board occupies a higher slot closer to rear of enclosure. The boards overlap slightly but they don't interfere.

We've avoided moving the heater transformer to the outside of the enclosure. The PS board now has a larger 50VA low noise toroidal type transformer for powering the dual heaters via a robust zero ripple switch mode dc-dc converter that runs at 600khz. The previous conventional transformer was working way too hard and too hot. Changing from a linear regulator to switching has also significantly reduce internal heat generation.

Prototype boards for the revised design have been ordered. I expect the boards to arrive by mid-month at which time I hope to report that the design phase is essentially done.

If all goes well I can see releasing the buffer towards the end of January.

tortugaranger

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Re: Hybrid Tube Buffer
« Reply #39 on: 16 Dec 2016, 03:44 pm »
Our PCB fabricator produced a bad batch of boards so they had to redo one of the prototype boards. Lost a week.  :duh:

Should have latest buffer boards in house by  midweek before Christmas (next week!) and check them out well enough to know whether we are done or not with initial development. If we are done then I will announce the release of the hybrid tube buffer for late January. Will take the time between now and then to accept pre-orders and get production tee'd up.

The combination of LDR attenuation with a tube preamp buffer is going to be awesome good stuff!  :thumb:

Cheers,
Morten