Quick Product Poll! Tube Buffer with Volume Control?

modwright · « **Reply #140 on:** 21 Nov 2019, 08:27 pm »

Hi guys, the nearly 13K views of this thread have not gone unnoticed and I have not given up on this product at all! In fact, I am nearing a point where I can pursue it fully as I am finishing two designs that have kept me very busy for the last year. The KWH 225i Hybrid power integrated amp is about to roll out and the Ai325, 300B 25W PP tube integrated has also been VERY WELL received by the first customers lucky enough to receive the first hand-built amps!

The next step is for me to lay out a matrix of options and ideas for this design. Things like quantity of inputs, balanced inputs/outputs, volume control, DAC supply built in, etc.

The plan is as follows:

A chassis will be designed to accept the buffer circuit and power supply design.
Enough room will have to be allowed for to accept the following (but not limited to) options:
Volume control, defeatable.
Tube rectifier.
Multiple inputs/outputs.
Separate power supply output to DAC(s) - ideal would be adjustable voltages and connectors for different DACs with wall wart supplies.
Balanced inputs/outputs - getting more costly here as this requires transformer coupling!

I do NOT plan on offering the following:
Tone controls.
Balance controls.
tape loop or any other processor loop (would like consider Home Theater Bypass however).
No DSP of any kind - purely analog design.

The plan being to design this in a relatively compact enclosure with a clean and simple face plate. Steel enclosure with black powder coat. Maybe silver and black face plates.
Basic model being just a buffer with no volume control and possibly two inputs and two outputs.

Starting price of this product to be < $1K.

Basic buffer circuit will offer:
Very wide frequency response - 20Hz - 100Khz
Very low distortion < .05%
Very low output impedance < 50 ohms.

As such, it will introduce tubes into the system without adding the typical soft bass, rolled off highs and added distortion. It will offer ideal impedance matching to your amp(s).

It can be used in a stereo speaker setup or with headphones.
It allows the system to be as simple as:
Source - Buffer - Amp - Speaker.
Source - Buffer - Powered Speakers.
Source - Buffer - HP amps - HP's.

In addition to being a buffer, it can ALSO be the UPGRADED linear supply for your DAC! I know that many people are getting tremendous improvements from adding external linear power supplies to a number of modern DACs.

This will be much cheaper than our mods to digital products and may be used with any number of different sources.
It can replace a preamp in a simple system and avoid the need to use the digital volume control built into many DACs!
With the DAC supply option, it also offers an upgraded DAC supply to a variety of DACs.

The key being to make this modular.

Please share your FB here as I take this from concept to reality!

Thanks,

Dan

jackox · « **Reply #141 on:** 21 Nov 2019, 09:59 pm »

I'd happy with all of these and be even more happy with balanced I/O

vanderstephen · « **Reply #142 on:** 21 Nov 2019, 10:48 pm »

I'm really hoping the home theater bypass can come to fruition.

modwright · « **Reply #143 on:** 21 Nov 2019, 11:54 pm »

OK, thanks. I believe that inputs will be relay driven, so that it is not hard to add HTBP, more than one input and optional VC, defeatable of course.

Balanced IO's require either op-amp circuits - NOT GOING TO HAPPEN - or transformer coupling, and this gets expensive! It could certainly be done and I would use PCB mount line-level Lundahls if so, because of their exceptional shielding and hum-bucking abilities. Because this will be sold direct, the cost does not have to be prohibitive, but that option WILL cost more.

Thanks,

Dan

Rusty Jefferson · « **Reply #144 on:** 22 Nov 2019, 03:09 am »

I really like the LPS tap(s) for sources. What are you planning on there, 5 volt 3 amp? Variable voltage? How many taps?

The Rang · « **Reply #145 on:** 22 Nov 2019, 03:26 am »

The basic model is probably all I need in between my Bryston DAC (and future phono pre) and KWI 200 integrated.
No volume control, 2 inputs.

Balanced might be nice but would it be balanced or normal RCAs, or a combination of both?
The Bryston has balanced outputs but any phono pre I buy most likely will not.

modwright · « **Reply #146 on:** 22 Nov 2019, 03:41 am »

As for LPS for DACs, I need to see what voltages are most common. 5V is very common of course and there are also others. There is also the issue of connector size, etc. We can work out a cable that connects to our unit at one end with a fixed connector and then has variable size connections on the other end. There is more to flesh out here, but yes, that is the idea!

jackox · « **Reply #147 on:** 22 Nov 2019, 07:18 am »

Just my opinion, I would not go for the DAC LPS.

Why ?
Highend DACs could benefit from the buffer, but not all (very few) uses poor external PSU.
Most uses inner good LPS or even better external.
But tube stage is not always an option for these.

+ I prefer an LPS specific for each of my gear units.
My only "shared" LPS is a HDplex but I bought it for that purpose and it feed only small boxes. The goal was to remove the SMPS out of my network.

OCD · « **Reply #148 on:** 26 Nov 2019, 11:57 am »

DAC LPS - make it an option.

Volume - defeatable = great!

HT bypass is a must have for me, and as I mentioned previously, have it default to this input when buffer is powered off.

I dont need balanced in/out, another option for some. RCA 3 in / 2 out is enough

No mention of remote control in your recent posts? please add a 3.5mm IR 'in' plug on the rear panel.

Hikmer · « **Reply #149 on:** 26 Nov 2019, 05:36 pm »

Same question, if there is no remote control...then I would not consider this device. Otherwise its on my radar.

Delta77 · « **Reply #150 on:** 26 Nov 2019, 07:56 pm »

6SN7 tube compatibility would a 6SN7 tube work well in my system.??
(Oppo 205 "6DJ8" & Decware ZMA "6DJ8" / "el34")

Remote Volume Control & Balanced in/out,
Are the options that are interesting me in this product..

I have my Modded Oppo 205, connected directly to my PP el34 amp with a XLR cable..
I have to use the Digital Volume Control on the Oppo 205, I would rather use the oppo wide open (100%) and have a remote volume control..

Does a volume control degrade the signal..? How.??

Thanks, BURT (From Fresno)

modwright · « **Reply #151 on:** 27 Nov 2019, 11:12 pm »

R/C volume is no problem for units with volume control.
It will be 6dj8, because this tube is best suited for the circuit that I am using. I know that the 6SN7 tube is popular, but it is not suited to the design I have planned.

Thanks,

Dan

Sonance84 · « **Reply #152 on:** 18 Dec 2019, 04:02 am »

This type of product is exactly what I'm looking for right now. My amp is 11K input impedance and I'm using one of your SWL 9.0 AE's with it, but would love a tube buffer in between them. I'd go for a basic version w/o volume control, but I'd possibly add the balanced outputs. And of course I would need a silver faceplate.

When can we expect these to come out?

modwright · « **Reply #153 on:** 18 Dec 2019, 06:19 pm »

I'm working on it!

The new KWH 225i Hybrid Power integrated and Ai325 PP 25W 300B integrated amp have been keeping me from it, but both are now at the finish line, so I am investing energy into making the Tube Buffer happen!

Look for more information after the holidays.

Happy Holidays to All of you!

Dan W.

HT cOz · « **Reply #154 on:** 26 Jan 2020, 04:28 pm »

Topping D90 is probably a good contender to review. https://www.audiosciencereview.com/forum/index.php?threads/topping-d90-balanced-usb-dac-review.10519/

I get that measurements are not everything but is it wrong to think they are the foundation to build on?

modwright · « **Reply #155 on:** 26 Jan 2020, 09:16 pm »

Well, measurements are important. I also prefer to listen in addition. Both are part of my process.

Based on the AKM DAC used and the measurements, it looks like a good product! I am not bothered by the higher frequency elevated THD+N and lack of Brick Wall filter because I prefer the sound of smoother filters. The price is very attractive. I don't know anything more about it, but it looks very tempting!

Dan

DarrellC · « **Reply #156 on:** 3 Feb 2020, 04:19 am »

Hi, any chance the enclosure size would be identical to the PH 9.0 which I own?

modwright · « **Reply #157 on:** 4 Feb 2020, 05:40 pm »

That is the plan! Yes, an enclosure that size would be ideal.

I know this is taking a while guys...very busy right now and I AM still working on this! It is a great product!

Dan

DarrellC · « **Reply #158 on:** 5 Feb 2020, 02:11 am »

Dan, if you get this pulled off I am in for one, please offer a fully balanced option, it is worth it to me.

modwright · « **Reply #159 on:** 16 Feb 2020, 01:01 am »

Thank you all, for your suggestions and your patience! The KWH 225i and Ai325 integrated amps have taken me much longer to finish than expected. The first KWH 225i's ship tomorrow in full production form and we have backorders to fill. The Ai325 will follow shortly thereafter. I will then pursue this design aggressively!

Dan