DIY Dodd Buffer

firedog · « **Reply #1060 on:** 7 Oct 2011, 05:15 am »

Sorry for the ignorant question, what's the difference between an SLA and AGM battery? Can't you run components interchangeably on either?

face · « **Reply #1061 on:** 7 Oct 2011, 05:51 am »

http://www.apexspeed.com/forums/showthread.php?t=38537

TrungT · « **Reply #1062 on:** 7 Oct 2011, 05:54 am »

Google:
Absorbent glass mat (AGM) is a class of VRLA battery in which the electrolyte is absorbed into a mat of fine glass fibers. The plates in an AGM battery may be flat like a wet cell lead-acid battery in a rectangular case. In cylindrical AGMs, the plates are thin and wound, like most consumer disposable and rechargeable cells, into spirals so they are also sometimes referred to as spiral wound. Their unique (for lead-acid chemistries) construction also allows for the lead in their plates to be purer as they no longer need to support their own weight as in traditional cells. Their internal resistance is lower than traditional cells due to plate proximity and the pure lead plates have lower resistivity, they handle higher temperatures better, and self-discharge more slowly.
These batteries are often referred to as sealed lead-acid (SLA) batteries due to their non-leaking containers.
Their specific power is very good and they can be charged and discharged quite rapidly. They are often used in high performance electric vehicles due to their high power density. An AGM battery is a lead-acid electric storage battery that:

-is sealed using special pressure valves and should never be opened.

-is completely maintenance-free.*

-has all of its electrolyte absorbed in separators consisting of a sponge-like mass of matted glass fibers.

-uses a recombination reaction to prevent the escape of hydrogen and oxygen gases normally lost in a flooded lead-acid battery (particularly in deep cycle applications).

-is non-spillable, and therefore can be operated in virtually any position. However, upside-down installation is not recommended.

praedet · « **Reply #1063 on:** 26 Oct 2011, 12:32 pm »

Anybody noticed the new "thing" that is coming?

"New Dodd Audio Remote LDR"

I had been thinking of making my own combination of a Warspeed (LDR) for volume control and an inline buffer with high-end caps and resistors to try to max out the capability, but now this has me in a wait-and-see mode...

jtsnead · « **Reply #1064 on:** 26 Oct 2011, 12:44 pm »

X2

I really would like it to have remote volume control!

Danny Richie · « **Reply #1065 on:** 26 Oct 2011, 01:28 pm »

There is also a new pre-amp based on the buffer design that will give you 18db of gain. It sounds just like the buffer but with a little more dynamics. It is a perfect solution for anyone that can't get away with a passive buffer design because they need the gain.

We used on of these on Sunday in our room at RMAF and it was outstanding.

praedet · « **Reply #1066 on:** 26 Oct 2011, 01:34 pm »

^^^So, as a relative newbie to the audio realm, if I really like my Buffer and I want to add a second one, should I get a preamp this time?

Atlplasma · « **Reply #1067 on:** 26 Oct 2011, 01:45 pm »

Quote from: Danny on 26 Oct 2011, 01:28 pm

There is also a new pre-amp based on the buffer design that will give you 18db of gain. It sounds just like the buffer but with a little more dynamics. It is a perfect solution for anyone that can't get away with a passive buffer design because they need the gain.

We used on of these on Sunday in our room at RMAF and it was outstanding.

Is that determined by the type of amplification you have in your equipment chain? Just curious.

Danny Richie · « **Reply #1068 on:** 26 Oct 2011, 02:56 pm »

Quote from: Atlplasma on 26 Oct 2011, 01:45 pm

Is that determined by the type of amplification you have in your equipment chain? Just curious.

It depends on the input impedance of the amp, the input sensitivity, the amount of gain needed to drive it, and the output impedance of your source.

At RMAF the big Reference Line amp that we used on Sunday needed some drive and the new pre-amp matched with it excellently.

roymail · « **Reply #1069 on:** 1 Nov 2011, 01:29 am »

Quote from: Danny Richie on 26 Oct 2011, 02:56 pm

It depends on the input impedance of the amp, the input sensitivity, the amount of gain needed to drive it, and the output impedance of your source.
At RMAF the big Reference Line amp that we used on Sunday needed some drive and the new pre-amp matched with it excellently.

What do you consider the average input impedance of a passive friendly amplifier? Thanks.

gld · « **Reply #1070 on:** 1 Nov 2011, 06:48 pm »

whats up guys? IMO around 50Kohms as a minimum,100k much better. The passive will work with lower input mpedanes, but it will be limited somewhere sonically in our hearing range.
Yes, I should have the circuit boards for the new preamp and the remote controlled LDR volume control. A build up and some testing then I will announce the availability and the pricing on both items. I will probably offer both in kit form of some sorts. Stay tuned
Gary

roymail · « **Reply #1071 on:** 1 Nov 2011, 07:12 pm »

Great to hear from you and know you doing well. Thanks very much for jumping in with this information. Looking forward to more about the new preamp. Will it be like the tube buffer with some gain?

poseidonsvoice · « **Reply #1072 on:** 1 Nov 2011, 07:52 pm »

Oooohhhhh. Interesting.

Anand.

MX48 · « **Reply #1073 on:** 15 Nov 2011, 12:08 am »

I'm an (old) beginner DIY'er without enough money to do what I want

, but of course want some sonic purity

.
I just finished putting together a 6 channel CDA254 kit from ClassDAudio and would now like to take the next step.

I have an Oppo 970HD as source player and Synergy clone speakers.

I am thinking of putting together a DIY Dodd Buffer. My understanding is I will need a DIY DAC of some sort. Will I then need a volume control or will the DIY DAC have that, or is it optional?

My DIY skills so far have been limited to sub and speaker builds before the CDA kit. But I think I am ready to take this on.

Of course my goal here is minimum dollars spent for maximum sonic gain

.

Any help would be appreciated.

If I have shown my ignorance already...well there's nothing I can do about that!

Thanks
Moto

Atlplasma · « **Reply #1074 on:** 15 Nov 2011, 12:35 am »

The Dodd buffer is two channel. Were you planning on multichannel playback?

MX48 · « **Reply #1075 on:** 15 Nov 2011, 12:51 am »

No, 2 channel.
I'm using the 6 channels for the active 3-way synergy clones.

Atlplasma · « **Reply #1076 on:** 15 Nov 2011, 12:30 pm »

Thanks for clarifying. I've built a buffer kit and also purchased one from Gary. It's a great piece of equipment. Gary also has a "Basic Buffer" that's even more affordable and might be a good fit for your set up. I would suggest calling or emailing Gary to confirm.

MX48 · « **Reply #1077 on:** 15 Nov 2011, 05:23 pm »

Definitely giing with the 1 in 1 out $150 kit. What is the least expensive way to power it? The battery kit is $250, that's more than I want to spend.

Also looking for a very inexpensive DAC, any suggestions?

Thanks
Moto

usp1 · « **Reply #1078 on:** 15 Nov 2011, 05:27 pm »

You can buy the battery and the ctek charger on your own for less.

face · « **Reply #1079 on:** 15 Nov 2011, 05:50 pm »

I finally picked up a pair of these buffers.

I'm looking for a small form factor battery to power them. Any recommendations? I only need 2-4 hours of battery life with 6H30's, thanks.