Pre Amp Kits

[RickH]

I am new to electronic DIY plan to build the Amp6. I will also like a kit to build a pre amp with tone control. Can anyone provide advice regarding he attached kits I have located, or recommend other alternatives? Thank you

http://www.vellemanusa.com/us/enu/product/view/?id=523679
http://www.quasarelectronics.com/1070.htm
http://www.canakit.net/ (Canakit model UK146)

[V-bro]

Welcome to the board Rick!

Only the Velleman shows s/n ratio, although the canakit looks pretty good quality too...

You can start-out with one and upgrade the components here and there ofcourse...

Why do you want tone control?


------X-max. can be several meters on any driver, too bad it can be done only once...------

[RickH]

Thanks for the reply V-bro. I plan to build a pair of speakers using the FR8.0C driver from Hemp Acoustics (http://www.hempacoustics.com/products.php). They are very efficient so I should be able to replace my existing receiver with the Amp6.

The Hemp Acoustics speakers are also very flat so I may not need tone control for the speakers. When the speakers are complete I will hook them up to my existing receiver to see if they need any adjustment. I was thinking of being able to compensate for room acoustics and my hearing - I'm particularly sensitive to high frequencies.

[V-bro]

Nice driver! I think it could go without compensation, but there are other ways to create compensation than to drive your precious signal through a couple of potmeters...

http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

------X-max. can be several meters on any driver, too bad it can be done only once...------

[RickH]

V-bro - it may be some time before I get the drivers but I'll let you know how they turn out. Thanks for the passive crossover suggestion. Maybe I will not need anything.

I've seen some DIY amplifier examples which have an input selector switch and volume control which may likely be all I need. I understand putting a ganged rotary switch to select input to the amplifier but how do you control the volume and where does the volume control go?

What would you use for input and volume controls?

[V-bro]

A 50K potmeter is excellent, middle pin (wiper) on the amp input (hot) and the side pins resp. to source output (hot) and ground (from source and to the amp tied together.

Changing the 'side' pins will make the volume change the other way around....

Make sure you get a double pot with 6 pins (stereo)...

------X-max. can be several meters on any driver, too bad it can be done only once...------

[V-bro]

Place the pot 'after' the input selector...

I use a separate input selector switchbox and made myself an external volume control box (in the photo gallery...)
http://www.okaphone.com/artikel.asp?id=1371

http://www.okaphone.nl/product/images/ASWITCH-3.JPG

------X-max. can be several meters on any driver, too bad it can be done only once...------

[V-bro]

I built this stepped 'ladder' attenuator, it even has a filter inside that can be switched on/off... It sounds really good, I matched the resistors myself so the left and right channels are always exactly the same volume...
http://www.41hz.com/gallery/V-bro/ladderpreamp.jpg

------X-max. can be several meters on any driver, too bad it can be done only once...------

[Mr T]

quote:Originally posted by V-bro
[br]I built this stepped 'ladder' attenuator, it even has a filter inside that can be switched on/off... It sounds really good, I matched the resistors myself so the left and right channels are always exactly the same volume...


Very neat, I like it [:p]

What's the filter done for ? LF cut ?

Mr T

[V-bro]

Thanks man! :) It's indeed a lowcut filter, 6db/oct somewhere under 100hz. You don't really hear the difference, but you can see the cone move far less....

It always has max. two resistors in the signal path (ladder), but I also made mini versions much like DACT (also with Elma switch) with built in HP and one with LP. They're also in the photo gallery. I use them with AMP9 in the car...[8D]

------X-max. can be several meters on any driver, too bad it can be done only once...------

[V-bro]

Uh, the mini versions are ofcourse series attenuators...but with well matched resistors they're still much better than any potmeter....

I matched the resistors to be 0.001% equal!:)

------X-max. can be several meters on any driver, too bad it can be done only once...------

[cfranz]

V-BRO,

How many resisters did you have to go through? .001% ??? [:0]


As for preamps kits, ever hear of these guys? <A href=http://sound.westhost.com/>ESP Audio</a> Lots of neat kits. Have no experience with the pre-amp yet... Working on an active crossover for some line arrays.



Carl

When the going gets weird, the weird turn pro.

[V-bro]

I went through ~20 resistors per value, I needed about 24 per deck, that's four decks= 96x20=

1920 resistors...

I got sick and tired of channel differences (or wanted to at least count out the possibility of it being caused by a lousy pot...)
;)

------X-max. can be several meters on any driver, too bad it can be done only once...------

[cfranz]

v-pro,

I'm thinking that that's more then sick and tired... that's anal retentive with a side order of maniacal.[:p]

so... how much to build me one? [:o)]

Carl

When the going gets weird, the weird turn pro.