looks like I might need a passive preamp

Rclark · « **on:** 29 Jul 2010, 10:51 pm »

any good kits or diy around that aren't too difficult to build bust most importantly do a great job?

Danny Richie · « **Reply #1 on:** 29 Jul 2010, 11:09 pm »

Here is your answer: http://www.audiocircle.com/index.php?topic=79766.0

jtwrace · « **Reply #2 on:** 29 Jul 2010, 11:12 pm »

Quote from: Danny on 29 Jul 2010, 11:09 pm

Here is your answer: http://www.audiocircle.com/index.php?topic=79766.0

+1

ebag4 · « **Reply #3 on:** 29 Jul 2010, 11:30 pm »

Quote from: Danny on 29 Jul 2010, 11:09 pm

Here is your answer: http://www.audiocircle.com/index.php?topic=79766.0

A BIG +2

NagysAudio · « **Reply #4 on:** 29 Jul 2010, 11:34 pm »

A buffer is not a passive preamp as OP requested...

HAL · « **Reply #5 on:** 29 Jul 2010, 11:44 pm »

The Dodd Battery Buffer is a buffered passive preamp. A current gain stage after the passive attenuator (volume control). Higher input impedance and lower output impedance than any passive preamp I have seen.

Rclark · « **Reply #6 on:** 30 Jul 2010, 12:14 am »

http://www.diyhifisupply.com/catalog/41

Wow thanks! But what do you think of the above as a wildcard option? I have zero understanding of why which one might be better. All I know is I don't want a resistor based preamp.

Edit, nevermind, I do now! Just looked over the buffer a bit more thoroughly, looks like a tube buffer with a nice piece?

Having the tube there doesn't ruin things? I thought a preamp was supposed to be as transparent as possible. Isn't a tube adding some kind of sonic flavor?

Again, no idea what I'm talking about in this area.

corndog71 · « **Reply #7 on:** 30 Jul 2010, 01:11 am »

I would also recommend Bottlehead.com for an active tube preamp.

The Foreplay III is an excellent choice and even The Quickie is a great little starter kit.

But if you insist on passive then check out goldpt.com for some high quality attenuators / kits.

Danny Richie · « **Reply #8 on:** 30 Jul 2010, 01:22 am »

No, the tube doesn't ruin anything at all.

None of the pure passive pre-amps that I have tried have come close to the buffer. Unlike a simple attenuator, the buffer is an impedance matching device.

So things like imaging and sound stage are typically MUCH better. It can also allow for better dynamics and drive capabilities in some cases that I have seen.

This particular recommended tube buffer puts very little in the signal path and is dead quite. It will rival most of the cost no object pre-amps out there.

TomW16 · « **Reply #9 on:** 30 Jul 2010, 01:25 am »

Quote from: Rclark on 30 Jul 2010, 12:14 am

All I know is I don't want a resistor based preamp.

If you are looking for a high quality autoformer, check out Bent Audio. Not inexpensive but very high quality.

Tom

S Clark · « **Reply #10 on:** 30 Jul 2010, 01:34 am »

The Dodd Battery Buffer kit has the sonic attributes of the Dodd battery pre. This one is a no brainer. Although there are several decent kits, the Dodd is world class. Please read the preamp reviews as the buffer is still too new.

http://www.stereomojo.com/Dodd%20Audio%20Preamp%20Review/DoddAudioPreampreview.htm
http://www.6moons.com/audioreviews/dodd/dodd.html
The 6 Moon review compares the Dodd pre favorably to preamps at $6K, and the kit buffer is $300+

Rclark · « **Reply #11 on:** 30 Jul 2010, 03:56 am »

So this pretty knowledgable guy on another forum suggested the 100K attenuator of the Dodd kit was "too high for what you want" and gave me this link

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

Otherwise I'm very interested in the Dodd unit. Stupid question: does it require a power supply? There was nothing about that on the site.

Thanks guys!

Jon L · « **Reply #12 on:** 30 Jul 2010, 04:05 am »

For those not wanting to deal with tubes or batteries, there's always the Pass B-1 buffered passive.

http://www.enjoythemusic.com/magazine/equipment/0708/first_watt_b1_preamplifier.htm

I hope it sounds as great as Dick Olsher says..because I just bought one

srb · « **Reply #13 on:** 30 Jul 2010, 04:14 am »

Quote from: Rclark on 30 Jul 2010, 03:56 am

Stupid question: does it require a power supply? There was nothing about that on the site.

It is battery powered. It's described on the Battery Powered Tube Buffer page, but I don't think it's mentioned on the kit page. http://doddaudio.com/BatteryPoweredTubeBufferPreamp.aspx

"You power this from any 12 volt battery/batteries you prefer and the proper charger to recharge them.

All units will be supplied with a cable consisting of a Neutric Power-con connector and alligator clips, of course you can terminate them to work best for your battery."

Steve

Rclark · « **Reply #14 on:** 30 Jul 2010, 04:21 am »

Apparently the "input impedance" of my amp is 25kohms. So the 100K attenuator of the Dodd will be a problem?

dvenardos · « **Reply #15 on:** 30 Jul 2010, 04:22 am »

If it was just passive that would be true, but as Danny stated the Dodd buffer has high input impedance and low output impedance which is what you want.
Goldpoint makes excellent stepped attenuators (I have a six channel passive that has been almost complete). They combine the elma attenuator (which is very highly regarded) with an easy to wire PCB. They would be a good choice, but again you have the impedance matching issue. With a totally passive preamp you have to trade off input impedance versus output impedance. With an output buffer you can have high input impedance and low output impedance that is impossible to do with a passive.

Quote from: Rclark on 30 Jul 2010, 03:56 am

So this pretty knowledgable guy on another forum suggested the 100K attenuator of the Dodd kit was "too high for what you want" and gave me this link

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

dvenardos · « **Reply #16 on:** 30 Jul 2010, 04:23 am »

No you need to look at the output impedance of the Dodd buffer, not the pot. The Dodd would not be a problem.

Quote from: Rclark on 30 Jul 2010, 04:21 am

Apparently the "input impedance" of my amp is 25kohms. So the 100K attenuator of the Dodd will be a problem?

Rclark · « **Reply #17 on:** 30 Jul 2010, 05:21 am »

Ha, you know what, ok, done. If you guys think it will work will with my amp then I'm just going to have to go ahead and do it. That Steromojo review described it as the Second Coming. (I'm starting with an inexpensive stereo amplifier, an Emotiva UPA-2, but after I have the system totally complete and up and running, I'm going to sell it and get monoblocks. Anyway.) I like that it's battery powered.

Why does he call this kit a "buffer" but the complete built unit is called a "preamp"?

Yeah so if there aren't going to be any problems running this unit with my amp I guess I'll stick it into my purchase chain.

I'm going to do more research though. I've never spent any time reading about preamps, and how the innards of all these electronic pieces work and connect, so it's pretty fascinating.

I'll keep looking at other options but I doubt I'll find anything as cool. I'm a preamp noob but it's obvious the Dodd is some kind of labor of love.

S Clark · « **Reply #18 on:** 30 Jul 2010, 05:45 am »

Quote from: Rclark on 30 Jul 2010, 05:21 am

Why does he call this kit a "buffer" but the complete built unit is called a "preamp"?

Because unlike the Battery Preamp, the Battery buffer does not have any gain. What it does have is the same sound. Before ordering, call Gary to talk about your system and goals. The guy is totally honest and will tell you if there are any issues. http://doddaudio.com/default.aspx

And by the way, you are going to love how batteries solve a host of problems. The music will come at you from a totally black background.

Rclark · « **Reply #19 on:** 30 Jul 2010, 06:20 am »

I'm actually pretty pumped. I was just going to be using a nice AVR as a stereo preamp but then I read on Emotiva's site they are coming out with this uber DAC in October and that if you pair it with the ERC-1 cd player (which I own) it takes it up a whole new level. However now I'll need a passive preamp to connect all these devices since the new uber DAC doesn't have HT bypass.

I've learned a lot today. Thanks guys.