DIY Dodd Buffer

HAL · « **Reply #1220 on:** 18 Feb 2013, 05:38 pm »

There are a few different Warpspeed style LDR volume control kits available. The Lightspeed is another possibility.

jk@home · « **Reply #1221 on:** 18 Feb 2013, 06:00 pm »

Quote from: Plund on 18 Feb 2013, 05:17 am

Hey JK, That's a clean build you have there. Very nice looking.

Thanks, couldn't of done it without all the help here.

Quote from: corndog71 on 18 Feb 2013, 05:17 pm

Where did you get the coupler for the volume control?

I got the complete kit from DIY HIFI, hoping that the metric shaft would fit the metric volume knob I got from Goldpoint. Ended up still fitting a little loose, so I added some of that JB Weld goop into the knob to fill it in and tighten up the fit (once it dried).

One could come up with a shaft extension much more cheap and cheerful with parts from your local hardware store, and/or a mainstream parts supplier like Digi-Key.

http://diyhifisupply.com/node/523

Plund · « **Reply #1222 on:** 20 Feb 2013, 03:02 pm »

Question. Anyone familiar with a 24v AGM battery charger quiet enough to leave on all the time? I have a 12v CTEK charger that I was planning to use with my buffer but now am considering powering one of the tk2050 amplifier boards (the higher wattage boards require at least 24v) with two 12v AGM batteries in series, and pulling 12v off for the Dodd buffer.

The CTEK 24v chargers cost more than the buffer and are too spendy for me. I may try one of the many <$40 chargers available on ebay...I just don't know which, if any, are quiet.

Pete

Danny Richie · « **Reply #1223 on:** 20 Feb 2013, 03:23 pm »

Those C-TEK chargers are worth the money man. They don't just recharge the battery, They will hit them with charge cycles that will extend the life of the batteries. I've had batteries that were old and wouldn't even take a charge get brought back to life with several cycles of charging that is suppose to de-sulfate them. And they are quiet.

gld · « **Reply #1224 on:** 20 Feb 2013, 03:24 pm »

Pete,
In all of my testing and trials I have found NO 24 volt chargers capable of being quiet or inexpensive.
I have tried many many different ones.C-Tek is most likely good but not cheap.
Also my experience with 24 volt battery systems they will always be kinda short lived.
Batteries are not created equal and charging them can be a pain cause 1 battery will always fill first and then the charger backs off so the other battery never fully charges and fails too early.
Biggest reason I redesigned my circuits to be used with 12 volt battery. Average battery life is now 4-5 years.
Always use C-Tek chargers and leave them connected. Very quiet!
Gary

cheapthryl · « **Reply #1225 on:** 2 Mar 2013, 06:01 am »

good circle, I enjoyed the reading.

Letitroll98 · « **Reply #1226 on:** 2 Mar 2013, 11:56 pm »

Thnx, and welcome to AC. Did you read all 62 pages.

JohnLL · « **Reply #1227 on:** 25 Apr 2013, 10:57 pm »

This is a question for those who run a Dodd buffer. I considered buying these a while ago but ended up with Intact AVC instead but the itch to try these has not left and I would most likely run them into the AVCs. The application is desktop and since the AVC I bought have four knobs they have to be in arms reach. My impression from the thread is that the 6H30 and the heat-sink run pretty hot. Does anyone run the 6DJ8? I would assume since it uses ~ 40% less current the heat from heat-sink and tube may be OK for me. Maybe another way of asking would it be OK to put the 6DJ8 in a vented box?
.

mikeeastman · « **Reply #1228 on:** 26 Apr 2013, 12:36 am »

I have a balanced Dodd tube buffer with 2- 6H30s and the only venting is the holes that the tubes stick out of and it doesn't run hot at all.

JohnLL · « **Reply #1229 on:** 28 Apr 2013, 03:07 am »

Thanks for the reply! I just finished skipping through the thread and somehow I had the wrong impression.

cheapthryl · « **Reply #1230 on:** 19 Jun 2013, 01:53 am »

Quote from: Letitroll98 on 2 Mar 2013, 11:56 pm

Thnx, and welcome to AC. Did you read all 62 pages.

Thanks and yes I've read it a few times now. What brought me here; I bought the buffer and a class d amp second hand and wanted to learn what I could. Great info here. Thanks again.

bardamu · « **Reply #1231 on:** 25 May 2014, 01:03 pm »

Hello,
After some information exchange with friendly Gary i did decide to order a selectable gain pre amp modified to work well with the 6085/e80cc tube because i like that one and because i have a lot of them in stock.
By doing so i am more willing to change the sonicap in the output by a better one.
I am sure there are better ones but i will have to do some googling. I love the Russian caps so far. Did spend a lot in the past on the so called high grade audiophile caps like Mit, solen, scr, wondercaps, sidereal.
The last few years the cap prices have gone trough the roof.
I wanna try russian petp caps too. Some say think they are to cheap to be good.
Anyway have to get a big battery and a ctek charger before being able to start comparing.
yours sincerely, Edward

Danny Richie · « **Reply #1232 on:** 25 May 2014, 01:35 pm »

The Sonicap with a Platinum by-pass is very good, but my personal favorite right now is the flat stacked Jupiter caps. That's what I am currently running in mine.

Nice choice. You'll really love it.

bardamu · « **Reply #1233 on:** 25 May 2014, 01:53 pm »

Hello Danny,
Sometimes adding a bypass could give you a sound that seems opr actually is not coherent. A bigger value or physical bigger cap will theoretically more need a bypass. So i usually go for the lower voltage. And in my loudspeaker instead of using one cap of 4uf i did go for 4 times 1uf in parallel
If the cap stays the same with the 6085 it will just be 3.3 uf. The petp russian 3.3 63 volts is small. The 4.7 k75-10 which i have in stock is 200 volts and it is rather big but i like it a lot in my crossover.
I allready did read about the jupiter and the dueland. They could be nice. But before buying i need to be sure it will be a big improvement.
I will keep on reading.
Sincere greetings, edward

Danny Richie · « **Reply #1234 on:** 25 May 2014, 02:32 pm »

Quote

Sometimes adding a bypass could give you a sound that seems opr actually is not coherent.

Not in this case.

And in a loudspeaker crossover the phase shift that a small by-pass cap can cause is above 20kHz. You cause problems is when you start using values as large as a 1.0 or bigger.

Hugh · « **Reply #1235 on:** 25 May 2014, 04:32 pm »

Ditto

Quote from: Danny Richie on 25 May 2014, 01:35 pm

but my personal favorite right now is the flat stacked Jupiter caps.

bardamu · « **Reply #1236 on:** 26 May 2014, 04:13 pm »

Hello, The voltage across or at the cap in the output of the Dodd preamp will probably be small so i started to have doubts about the necessity of using 600 volts dc caps. There are some duelands and some jupiters who could be very nice.
If i would decide to spend 100$ or more on a cap i want it to be nice. I mean very nice. If spending 150 instead of 100 would be better i would choose the 150 one because the 100$ cap would end up in a box after buying the 150$.
But i still remember the MIT high tech caps being largely surpassed by a 40 year old Philips surplus cap. That was in loudspeaker crossover.
But now we are talking about an output cap for a pre amp.
Sincere greetings, Edward

bladesmith · « **Reply #1237 on:** 27 May 2014, 07:57 am »

Mundorf M-Cap Supreme Silver/Oil.

bardamu · « **Reply #1238 on:** 27 May 2014, 05:37 pm »

Hello,
Of course i did come across these caps. I have been trying to read between the lines and to me the jupiter and the duelund seem to be more my kind of thing. I am willing to sacrifice some detail. When i like to listen to music i like to enjoy. Not being aggitated to much because lots of recordings sounds so mediocre.
BUT first we will see how the pre amp sounds with the standard cap. Find out what will be the maximum dimensions of the cap. Find a supplier that can make a close pair and then just order.
Sincere greetings, edward

Garytr · « **Reply #1239 on:** 29 Nov 2014, 05:40 pm »

Does anyone know what codec is used for the Dodd Buffer remote control board?