Active valve monitors?

[EbanX]

Hi everyone,

im currently a final year student and planning to make my final year project based around active valve monitors. This is a new concept for me and was wondering if i could get some help with questions i have!!

The design i wanted for example would be 2 or 3 way active valve monitors (a pair of them).

My initial idea was to have the bass driver using its own separate amp that does not use any valve components (FET amp kit) and tweeter (for 2 way) to be powered by a valve amp kit. iv done a little research and it does not seem impossible!!

i know its not guna simple to make and thats why i need some input and help!!

also i would need some sort of active cross over for the highs and lows before the signal goes to the active amps??

also im trying to devise a way of powering my active monitors with one power source for each monitor ( like 1 or 2 transformers for all components) if this can be done ...

iv looked at some amp kits using valves and others using FET amplifiers

this seems to me that this circuitry can be combined to make the final result im after ( valve and ??

obviously this seems a little bold for my project, but i would love to know if this can be achieved..

please could people get back to me on this one as i would be most great full and any input is a bonus at this stage!!

many thanks EbanX

 

[Eli Duttman]

Young man, you present the membership with a VERY thorny problem.

As a student, you rate to have highly limited financial resources. Tube/valve electronics cost more to execute than SS.

Have you given thought to the ventilation problem you are going to have with tubes inside the speaker "box"? How sensitive are the speaker drivers you plan on using? What is the AC mains voltage in your area?

 

[chrish]

Hello Ebanx.

You have not stated what subject or course you are studying. This might make a difference to the level/type of advice that is required. Are you expected to come up with a design concept, or are you concerned with the electronics? Also, if you are able to access woodworking/metalworking facilities on campus, can you etch your own circuit boards?

Also, if you state what country you are from, people will be able to advise on voltage requirements for transformers, and also importantly, suggest where you might source parts from.

Here is a good site that talks about active crossovers that might be helpful. http://sound.westhost.com/project09.htm

Anyway, more information about what you are trying to achieve, and where and why will result in some more focussed assistance.

Good luck with the project.

Chris

 

[EbanX]

Dear Eli Duttman and Chris,

Firstly thanks for the replies.

Eli Duttman,

My first idea for the enclosure design would be half open baffle, so basically i would have an enclosure for the bass unit with a vent to optimise the bass response and have the tweeter in a open baffle where the valve amp kit would sit on top of the enclosed bass unit so the heat problems should be ok like this?

iv done some basic research into prices for small valve amp kits and prices seem to be manageable for this. the mains voltage here is 240V AC ? i have currently have 6-7inch bass drivers and about 3-5 inch tweeters, but im not sure of there output just yet as they do not have any numbers on them (they were given to me and are brand new) hopefully i can test them soon to find out, i hope this helps.

Chris,

Im currently studying in the U.K and my course is BENG Audio Technology at degree level undergraduate. i have access to wood work facilities and electronic equipment with regards to testing and making my project.

Yes i am concerned with the electronics mostly with power matching all the parts together and devising a way of getting power to my speakers as we use 240V AC over here. Thanks for the link i will check it out!

i had a look on ebay for amp kits and some good result came up! i can give you the links if you like so can have a look at them possibly?

hope this information helps for you both and thanks agian

regards EbanX

 

[wa2ise]

You may want to do it similar to guitar amps. As in having the amp in a "head", above the speaker enclosure. There might be an issue with some tubes being microphonic, that is, vibrations from the speaker can rattle the grids inside the tubes and modulate the signals being amplified. Some rubber feet on the head can reduce this

 

[sreten]

Hi,

Doing a project on something you know very little about is
never a very good idea in my book. However there is no
reason why it cannot be done. Doing it properly is a
different kettle of fish with a very steep learning curve.

rgds, sreten.

http://sites.google.com/site/undefinition/diy
(see if nothing else, the excellent FAQs)
The Speaker Building Bible
Zaph|Audio
Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter
http://audio.claub.net/Simple Loudspeaker Design ver2.pdf
FRD Consortium tools guide
Designing Crossovers with Software Only
RJB Audio Projects
Jay's DIY Loudspeaker Projects
Speaker Design Works
http://www.htguide.com/forum/showthread.php4?t=28655
A Speaker project
DIY Loudspeakers
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design

Great free SPICE Emulator : SPICE-Based Analog Simulation Program - TINA-TI - TI Software Folder

 

[chrish]

Some good info on Siegfried Linkwitz's site. I built a sub woofer based on the one in his pluto 2.1 system with active crossover and a transform circuit using a ebay sourced chip amp module. I then did active crossovers to small fostex bookshelf speakers powered by a Tubelab SSE amp. It is a very good system!