Quick Product Poll! Tube Buffer with Volume Control?

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paul79

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Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #60 on: 13 Jan 2019, 11:50 pm »
Yes please. Add me. I also wouldn't mind evaluating it, and maybe help tune it if that is possible? I don't claim to be the end all or highest on the audio pedestal. I really do not want to come off that way, but do have a good idea of what I like and expect in a component. Ask Richard Colburn about me. He knows me quite well.

Speakers: Joseph Audio Pearl 3's
DAC: Totaldac Twelve MK2
Totaldac Server
Accuphase amps
Sutherland Line Stage
Room is big and treated nicely.
Zenwave for all analog
WyWires power cables

Looks great in there by the way!

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #61 on: 13 Jan 2019, 11:53 pm »
Will do! If you shoot an email to: modwright@yahoo.com, I will be sure that Kristin adds you to the list and you will be contacted when we have product to demo.

At this point, I am moving forward with the design.

Thanks,

Dan

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #62 on: 23 Jan 2019, 10:42 pm »
OK guys, I am moving forward with the design for the 'Analog Bridge' tube buffer.

I have a lot going on right now, so be patient, but I do believe this product 'has legs'. I am working on an enclosure design and the first product will be RCA in and out, one set of inputs, probably two sets of outputs. No volume control. It will be a buffer/impedance matcher with very low distortion, wide bandwidth tube circuit. It can be used between any source with built in volume control, straight to your amp. It can also be used between any passive preamp/attenuator and amp.

The two things that this product will bring to any system, is the 3-D body and weight of tubes as well as an excellent impedance match to your amps. With an ouptut impedance of < 100 ohms, it is ideal for this purpose.

Target price is $750 with (2)6dj8/6922/7308 tubes.

Once the initial design is out and I see how it is received, I will look at the following options:

XLR outs.
Volume control (w/bypass)
Multiple inputs.

I want to start with the simplest and cleanest design concept first to prove its worth and success.

Thanks,

Dan W.

paul79

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Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #63 on: 22 Feb 2019, 06:11 am »
Excited about this! Any news?

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #64 on: 22 Feb 2019, 04:46 pm »
I'm sorry but I have been been buried recently, finishing two integrated amps and a new tube mod for the Pioneer LX-500. The amps are debuting at Axpona in April and I am buried. I have not forgotten this project!

Thanks for your patience,

Dan

jriggy

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #65 on: 22 Feb 2019, 05:02 pm »
Good. Yes, don’t forget about it :)  a MWI tubestage to throw between a passive and amp would be cool.

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #66 on: 22 Feb 2019, 05:09 pm »
I really just need to design an enclosure and the rest is good!

I will get this done after I send off the order for PCBs and other materials to mfg for the two integrated amps.

Thanks,

Dan

jackox

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Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #67 on: 19 Apr 2019, 08:59 am »
If there is multiple inputs, volume control bypass and XLR outputs I am in !
This would help my setup with sound quality and source input problem with my current processor and maybe future one.

RDavidson

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Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #68 on: 19 Apr 2019, 01:56 pm »
One input and two outputs is PERFECT for the many many folks going from volume controlled DAC to amp. The second output allows for subwoofer out (or 2nd amp)....which most DACs don't accommodate.

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #69 on: 19 Apr 2019, 04:17 pm »
OK, I am getting there. I just got back from Axpona and recovered for a couple of days. Three new product releases there and leading up to the show about did me in.

I am getting back to the buffer design and will share my results as it progresses.

Thanks,

Dan

GregC

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #70 on: 1 May 2019, 04:27 am »
Hi Dan,

The basic design makes a lot of sense to optimize DAC performance direct to amps and allow for sub integration. 

I see you plan to expand the design after the initial release with a bypass option and XLR outputs.  If you could squeeze in one additional analog input (to integrate your wonderful PH 9.0 *wink *wink), that would be the cat's meow. 

Greg

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #71 on: 1 May 2019, 05:15 pm »
OK, so I have been doing some thinking about this project. Its scope could be from slim to broad. Does it make sense to design the enclosure such that it can accommodate all options as stated below?

1) Basic: Unity Gain, (1)pair RCA in, (1) or (2) pair RCA out.
2) Transformer coupled inputs allow for 0, 6, 12dB gain. This would not work with a passive, unless Transformer based VC, because of impedance matching. There is a sonic magic to transformer coupling. There is full galvanic decoupling, and a quality to the sound that comes from inductive coupling which is exceptional! This also achieves optional gain in a way that I prefer!
3) Volume Control: Volume control would be switched between input transformers and buffered output stage.
4) Multiple Inputs: Say 1-3 inputs, 3-way toggle. No need for expensive rotary selector or relay switching and PIC or microprocessor controls which unnecessarily complicate the design.
5) Balanced outputs: This could be accomplished with another pair of output transformers (expensive cost add).  Or, with input transformer coupling, the use of four tubes could also accomplish the same goal. Best sound however may be achieved with transformer output coupling.

Summarizing options below, please let me know which configuration(s) would be of greatest interest to you.

Simple RCA-RCA Buffer.
Volume Control, switchable in or out.
+6dB, +12dB transformer based gain.
Multiple inputs.
XLR fully balanced outputs.

This begins to look more and more like a preamp, when you add in all options. I suppose it is a matter of semantics, but my goal is to produce a unit that will be the 'Analog Bridge' between your digital and analog source(s) and amplifier.

I would like to keep the size of the product fairly compact. It could be 17"W, but not necessarily. If a simple bridge, it could easily be 1/2 width.

What sets this apart from a preamp?

A preamp typically has remote control. This could be done, but then we are looking at adding a PIC and digital controls with clocks and other high frequency artifacts that would not be present in a simpler design.

A preamp typically has active gain and ideally a buffered or low output impedance.

A preamp may offer balance control, Home Theater Bypass, tape loop, etc. I don't want that level of complexity.

A preamp is a very active device. This would not be a passive device, but using transformer coupling for gain and unity gain active stage means there is VERY little room for noise to be added. Our power supply design and layout will rule noise out.

Simplicity and sonic purity are the goals of this project. I also want it to be affordable. It need not be dripping in billet AL and weigh 50lb. If offered factory direct to our mod customers, it could be reasonably priced. The more feature laden option would be  more expensive of course, but still reasonable.

This could suit a main 'big rig' 2CH system.
It could work for a desktop system with powered speakers.
It could work with a headphone system.
It could be scaled to meet your needs!

Please post your thoughts and desires per my above comments.

This product WILL come to market, but I see an opportunity to make a very versatile product here, that would be unique and suit many peoples needs well.

Thanks,

Dan Wright
President, ModWright Instruments Inc.


GregC

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #72 on: 1 May 2019, 05:27 pm »
Hi Dan,

Your description sounds great. The buffer would be flexible for something as simple as a tube buffer with volume control to a stripped down version of a preamp.  The half width would be preferable.

My needs are:

HT bypass (preferably a relay when unit is turned off)
2 outputs, one for speakers (my amps are balanced XLR only) and one for sub.
One analog input for phono stage.

Remote may be nice (for mute and volume), but not if it makes the case larger and adds too much cost. 

Greg

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #73 on: 1 May 2019, 05:39 pm »
Thanks Greg, adding R/C and HTBP means that it would have relays, PIC and controls. Not a problem, but some added complexity and cost. Not a sonic disadvantage, just cost.

I appreciate the input! I can't move forward until I have an idea of what people want.
I plan to make it modular, so that it can be configured with different options that can also be added later.
Things like controls, HT/BP and R/C would likely be part of the core unit if the decision is made to include it.

I suppose this DOES become a replacement for a preamp.

The initial goal of this design, honestly, was to offer a low cost 'external' tube mod circuit, for use with any stock digital unit. After I built it, and I had a couple of people listen, I realized that it works well with all sources, analog and digital. Many people want to add tubes to their system, but don't necessarily want tube amps. This is meant to fit that need, as alternative to tube mod or tube preamp.

Thanks,

Dan

GregC

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #74 on: 1 May 2019, 05:46 pm »
Hi Dan,

I just sold an Exogal Comet DAC, and it sounded excellent when I tested it direct to my amps (clean and transparent).  However, it sounded better when I ran it through my preamp.  I assume the tube buffer would add a similar impedance match as a preamp to make a DAC sound its best direct to amps, but at a lesser cost.

Greg

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #75 on: 1 May 2019, 06:40 pm »
Yes, absolutely!

Cave

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Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #76 on: 3 May 2019, 02:57 am »
Just curious, I know the Oppo players can drive some amps without a pre since it has built in volume, ~2.1 volts out and low impedance. I have a Levinson amp with 50K input impedance. Works well. Placed a schiit sys attenuator in between since I wanted to use outboard control, as some say the Oppo bit strips. Maybe. Anyway the schiit &%$! the whole sound. Replaced with a quality Goldpoint, transparent and works well. (I like it better than the Khozmo)

So I decided to plug a Manley Chinook phono stage (50 ohm output) straight to the Goldpoint. Works very well. Not sure why there's a feeling that digital source only can work great without a pre. I can get 100db across the room with some attenuator steps to spare.  (JBL 89db efficiency and also a pair of JBL 93db)

jackox

  • Jr. Member
  • Posts: 31
Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #77 on: 4 May 2019, 03:12 pm »
My needs would be :

RCA input X2
XLR input X1

XLR ouput X1

vanderstephen

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #78 on: 4 May 2019, 08:14 pm »
I'm definitely interested. My needs would be volume control and two inputs. One input connected to a phono preamp and the other for home theater... Either HT bypass or use as unity gain.

modwright

Re: Quick Product Poll! Tube Buffer with Volume Control?
« Reply #79 on: 6 May 2019, 06:34 pm »
OK and thanks guys.

Analog or digital can work just fine into a passive attenuator. The problem with just a passive attenuator is that the impedance match between the passive and the amp input is not ideal. This can result in HF rolloff and will result in less drive and body.

The only reason that I first recommended the Analog Bridge as a solution for Digital is that the tube analog stage will make so-so digital sound much better. It is also a very high bandwidth, low distortion tube circuit, so it will not add unnecessary noise and distortion to any signal, digital or analog. What it will do, however, is offer the ideal impedance matching to any amp. The output impedance of the Analog bridge is < 100 ohms.

Thanks,

Dan