Ground planes and solidstate?

[Nordic]

The though struck me that the PSU may be guilty in the noise thing, as it plays fine from the capacitors the moment I cut the power... not saying the sockets aren't playing a role though.. have nothing to loose in trying your suggestion.

 

[carlmart]

Im pretty good at woodwork (another school subject of mine -don't worry the rest were science, biology and two languages...it wasn't all holiday)

So I expect to be able to follow a pretty well established design with minimal costs above the materials and components... money is always tight, as I am medicaly boarded.... at least I have lotsa time.... way too much, concidering I only sleep about 5 hours a night.

That's exactly one problem with speaker design: woodwork has very little to do with modern projects.

In the past you could build some designs because the speaker manufacturer itself provided the plans and all the speaker parts: croxxover, horn, drivers, etc. Tannoy and Altec were some of them.

Kef also had one DIY speaker kit, where you only needed to provide the box.

Things are not like that anymore. Drivers are much better, but not so easy to tame. Speaker shops may try to sell you the idea that it is an exact science, but it's not: it's art. After you understand all the variables, and there are many of them, you start working on the little things your experience taught you.

I can say that because a great friend of mine, in Argentina, makes high quality speakers. And he has taught me a lot. We still have your different opinions, as it should be on strong character people, but I do respect his knowledge.

Believe me: if you can don't DIY your speakers. Or if you do take them to a comparison with high quality types.

Yep I like the equaliser idea, I have the scematics and PCB plans for a 9 band stereo unit, just have to take the plunge and buy the 18 slider pots at some stage (mondo expensive).

That sounds to me as a graphic equalizer. That's not the one I mentioned. Look for a parametric equalizer project, which will allow you a much better control. You will need high quality pots, and slider pots are not the best you can find. You may find concentric from Alps that are very good.

 

[Nordic]

I have heard 2 sets of DIY boxes from local guys I met through this site... and they were pretty good...

I agree it is a science, but I also feel I can follow one of the designs from our wonderfull forum. I do not plan to do any engineering... more blind following of the plan...

When I have to choose between the junk available in my price bracket in the shops its a no go, and I am 300% sure I can improve on those.

One of the reasons I have not started such a project yet, is exactly because of hard the science side of things are... have been following oodles of threads for a year or so.. and know the physical construction could well turn out to be the easy part.

Will look at the equaliser though

 

[Nordic]

I give up, even built completely new PSU using starground... plays nicely for a few minutes then the sound goes freaky.....

 

[AndrewT]

Hi Nordic,
can you confirm that all works well when you omit the buffer, i.e. source direct to amplifier?

 

[Nordic]

Yep absolutely! If only it didn't sound so good while it works....

Cant believe the valve pre gave me so litlle problems in comparison, to build.

 

[AndrewT]

Hi Nordic,
did you correct the discrepancies between the schematic and the protoboard?

What is the output impedance of your valve pre? Mine (Croft) is over 1k0 and I would like to lower it a factor of ten.

 

[Gordy]

Hello Nordic,

(I have not read all of this thread, so if the following links have already been provided then my apologies).

The buffer is detailed in the following places:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=87911&perpage=10&highlight=&pagenumber=2

http://myweb.tiscali.co.uk/nuukspot/decdun/gainclone2.html


G.

 

[carlmart]

I give up, even built completely new PSU using starground... plays nicely for a few minutes then the sound goes freaky.....

Can we relax for a minute?

OK. To start with let's consider or confirm what DOES work.

1) Buffer with 547s.
2) Different voltages with these transistors.

Things to eliminate until further notice:

1) Transistor sockets
2) Output relay

If you can confirm that the buffer works as above for longer than a few minutes, then we can go on. It does?

Please also include a careful drawing on how the PSU is now and how you did that starground.


Carlos

 

[AndrewT]

Have things become a bit strained overnight? Some posts have disappeared.

 

[thanh]

HI!
My system:
sound card--> pre-amp with gain 10---> bass-treble--> power amp. So Do I add a buffer ?
Thanks! Hoping this post doesn't make off topic

 

[carlmart]

My system:
sound card--> pre-amp with gain 10---> bass-treble--> power amp. So Do I add a buffer ?

No, you don't need one. As long as the bass-treble control is active.

IMO the order of your chain is wrong: the bass-treble should be before the preamp, as long as that's active too. In that way, if you increase your levels due to eq you can adjust them with the preamp.

The preamp, if it's active, should be acting as the buffer.

 

[thanh]

Thanks Carlmart!

 

[thanh]

Why do we need a buffer ?
I think:
- a buffer increase signal power although voltage gain is 1
- to avoid that power amp distor signal source
bye!

 

[AndrewT]

Hi,

Why do we need a buffer

to match the source impedance to the receiver and to match the receiver impedance to the source.

Nothing to do with power.

 

[thanh]

to match the source impedance to the receiver and to match the receiver impedance to the source.

Yes! I were too
Output impedance of buffer is very low but Input impedance of power amp is very high: 22k Symasym . Industry standard seem to be 47k.