[TrungT]

Snap shot a hi-rez pict.
Lucky, we may spot something.

[setamp]

Question for all with experience with this buffer.  I am looking to buffer the signal from my EE Minimax Dac (22k Zout) and my Beta22 (46k Zin).  I am thinking of the inline buffer as I need only 1 set of ins and outs and already have a stepped attenuator in my Beta22.  There is no reason to add anything further, right? (except possibly bypass caps, battery and tube).   Thanks.

[jk@home]

Are you looking for a pre-built completed unit from Gary, or just the kit to roll your own?

[setamp]

Are you looking for a pre-built completed unit from Gary, or just the kit to roll your own?

I could go either way.  The pre-built inline unit seems to be a real bargain at its price.  The kit is tempting just to try my hand at the build. 

[jk@home]

I'm building one from scratch, and have already spent more $$$ than if I were to have just bought a completed one from Gary.  My choice obviously, but I wanted a Goldpoint pot and panel voltmeter installed, in a larger chassis. Arn at Goldpoint even suggested I could add a selector switch to switch in/out the buffer stage. No plan to do that now, but will have the "real estate" in the chassis available if I choose to later.

If you go with the prebuilt, you will need what you listed plus at least one (gray, not blue) male powercon connector, #NAC3FCB and a 2 conductor wire cord to go from unit to battery. Also a CTEK battery charger. Plus an inline fuse at the battery isn't a bad idea.

Or just buy the power kit from Gary.

If you do the kit you will need the above plus a female powercon, could throw in the 6A10 diode for power protection, and bypass platinum caps for extra performance (I did). Fuse holder with 2 amp fuse, toggle power switch, chassis mounted RCA connectors, hookup wire, connectors, maybe some type of terminal barrier or solder strip, and a chassis.

I'm also adding one of the nice voltmeters from Jamestown Dist. on the front panel, opposite the Goldpoint pot knob.

http://www.jamestowndistributors.com/userportal/show_product.do?pid=13048&familyName=Faria+Chesapeake+Series+Gauges

To go a step further, you can build a battery box. In mine I will have one input (blue), two output (gray) powercons, a HD STDP toggle switch to control both outputs, fuses on each output with "blow" indicator lights, and a panel mounted voltmeter.   

If I missed anything Trung can help out here, he's built a few of these things. 

[setamp]

Thank you very much.  In your opinion, is this a good way to address the impedance differential between my minimax and beta22?  It seems to be a better sonic (fewer parts) and cost effective solution than adding a pre-amp to the mix.

[TrungT]

Jk@home list everything you needs to build the Dodd buffer. 
Dodd buffer impedance 100k if you using 6H30DR tube, and the impedance change according what tube you are using.
I think Gary build a 1 in, 1 out with Goldpoint pot for Roymail and he's very please with it.
Gary build - cost little more but more resale value.
DIY kits - save money
The choices is your. 

[jk@home]

Thank you very much.  In your opinion, is this a good way to address the impedance differential between my minimax and beta22?  It seems to be a better sonic (fewer parts) and cost effective solution than adding a pre-amp to the mix.

Not familiar with your stuff, but I came up with the same conclusion. I'm using a Channel Island DAC with an output of 825 ohms, a power amp with an input impedance of 22k ohms, and a passive preamp in between..

Right now I'm using a CI passive pre, and tried an old MF X-10 D tube buffer between it and the amp. Showed my MMG speakers like a little bit of tube stage in the system.

Hoping the Goldpoint/Dodd setup will give me that sound but with better resolution than the Musical Fidelity buffer offers.

[rodric]

Hi,

This is my first post on this forum, but I've thoroughly enjoyed reading it. 

I've been enjoying the DODD buffer for several weeks now and really like what it does.  I am though, having trouble with a low hum noticeable over 10' from the speakers.  From what I read, it seems I should have no detectable noise from the speaker and certainly not that far away.  Could you advise if there is anything else I should check in troubleshooting?

- I am using 2 Class D audio CDA 254 running mono.
- My setup is silent, dead silent without the buffer. Removing the buffer from the setup returns it to dead silent.
- The noise exists even if the buffer is not on.  It is slightly louder when on.
- Using the Sovtek 6H30PI with 12v selected.
- The unit is still bread boxed as I trouble shoot this.
- All indicated ground points,  2 PRP 100K, and negative side of the battery terminate to the same point.
- If the CTEK 3300 is connected, there is additional feedback, especially if it kicks in to charge rather than trickle.  It is unusable while listening.
- Using a UB1250 battery or an large Odessy I plan to run the amps on eventually as well.

My next step was to try something other than speaker wire as my power wire from the battery to the buffer.  I suspect it may be some sort of ground issue though, as it seems everyone else can leave there CTEK connected 100% of the time. 

Do you have any other suggestions to try?  Thanks in advance for any advice.

[rodric]

Arn at Goldpoint even suggested I could add a selector switch to switch in/out the buffer stage.

Do you have more information on how to do this and what to order?  I'd love to have the option to bypass for a/b testing and home theater use.

Thanks!

[Torkild]

Wondering would it be possible to use this to change a singel ended rca to a differential output and still enjoy the great tube buffer.
I would want to have it feed a asx2 icepower amp in BTL mode, and it needs a differential signal to do so.

Also this amp have 24V dc Auxiliary Supply and supports max. 250mA.

Can it be done? If so, how should it be wired?

[face]

Do you mean balanced output?  If so, to be fully balanced, you would need a second kit.  Together, they would still need a 12V input, but the mA would be higher.  I'm FYI, I'm using a 12v, 4.5A solid state power supply to feed a pair of buffers in balanced configuration.

[TrungT]

Rodric
Welcome to AC. 
" Using the Sovtek 6H30PI with 12v selected "
6H30 is 6V tube, so you may try to switch back to 6V and see if the noise still there.
Dodd buffer with ClassD amp does make a tube hiss sound but only your ear next to the tweeter.

[jk@home]

Arn at Goldpoint even suggested I could add a selector switch to switch in/out the buffer stage.

Do you have more information on how to do this and what to order?  I'd love to have the option to bypass for a/b testing and home theater use.

Thanks!

I didn't go there with him, but here's the Goldpoint switcher page.

http://www.goldpt.com/selector.html

If using just a 2 pole switch in between the volume pot and buffer, with one switch output leg going to the buffer input, and the other going directly to the output female RCA, there would be a back feed into the buffer caps when switched over to the "no buffer" position...problem? You would have to ask Gary on that one.

Another solution would be to do the above, but just have two sets of output female RCAs, one set off the buffer, the other directly off the "no-buffer" position of the switch. Of course then you would have to move the output interconnect cables whenever you switched over. PITA, but simpler.

I guess a third option would be to get a 4 pole switch and switch in and out both the input and output of the buffer. That would be more contacts in the signal path, but may be ok.

[rodric]

Rodic
Welcome to AC. 
" Using the Sovtek 6H30PI with 12v selected "
6H30 is 6V tube, so you may try to switch back to 6V and see if the noise still there.
Dodd buffer with ClassD amp does make a tube hiss sound but only your ear next to the tweeter.

Thanks Trung.

I emailed Gary today too.  He told me since its picking up noise before its even on, its getting feedback from somewhere.  Following his advice, I moved the amp and anything else with AC away and shortened the 7' cable to the battery.  Its much, much better now.  Only some hiss now with my head about a foot from the speaker.  I am re-thinking my single integrated amp build to several small shielded "shoe boxes" instead.

I am still getting an unacceptable amount of feedback if the CTEK 3300 is plugged in concurrently though.  Bad house wiring perhaps?  I'm at a loss.

I'd say the tube actually sounds better (to me) at the 12v setting, although I would guess I'm shortening its life.  The switch runs noticeably hotter on the 6v than the 12v setting too.  No noise difference in either mode, but a considerable difference in glow!  Have I ruined it running it so long incorrectly?  Did the forum ever come up with a list of suggested tubes or does everyone pretty much run the 6H30 DP and call it a day?

[rodric]

I didn't go there with him, but here's the Goldpoint switcher page.

http://www.goldpt.com/selector.html

If using just a 2 pole switch in between the volume pot and buffer, with one switch output leg going to the buffer input, and the other going directly to the output female RCA, there would be a back feed into the buffer caps when switched over to the "no buffer" position...problem? You would have to ask Gary on that one.

Another solution would be to do the above, but just have two sets of output female RCAs, one set off the buffer, the other directly off the "no-buffer" position of the switch. Of course then you would have to move the output interconnect cables whenever you switched over. PITA, but simpler.

I guess a third option would be to get a 4 pole switch and switch in and out both the input and output of the buffer. That would be more contacts in the signal path, but may be ok.

Thanks for the response and link.  Once I get my feedback problem sorted, I'll play around with it.  If I get my feedback sorted and the ctek can stay on all the time, I may be temped just to keep it simple and use it all the time.  I thought it would be nice to bypass for standard TV watching though.

[TrungT]

Rodric
6H30DR tube is the best sounding tube for me.
The older date code is the better it sound. 

[rodric]

MUCH BETTER NOW!  I found that the ground to the voltage selector was very loose and came right off with a gentle pull.  If I moved it and got it just right, the feedback went away.  A spot of silver solder, and most of the noise problems went away.  I'm sure the right voltage helps too

Trung, thanks again.  I'll try to find a 6H30DR tube to try as well.  I'll put it all back in the case and take a pic of my Staple's provided integrated amp case.

The only problem remaining is, the CTEK still cannot be connected while I'm listening.  Inconvenient, but not a show-stopper.  However, everyone else on the forum doesn't seem to have the same issue with listening with the charger connected.  Any Ideas?

[TrungT]

Rodric
What's battery amp hr?
Check your PM.
 

[jk@home]

...The only problem remaining is, the CTEK still cannot be connected while I'm listening.  Inconvenient, but not a show-stopper.  However, everyone else on the forum doesn't seem to have the same issue with listening with the charger connected.  Any Ideas?

I remember reading at least one other person having a noise issue with the CTEK. There was a battery box posted in this thread or another here at AC where some power filtering was added.

I myself have an issue of leaving it plugged in all the time due to lightning storms and power surges we get around here. So my solution was to buy two 18 AH batteries and only plug in the charger when needed.