PICS: GainClone Monoblock pics

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Hi,
I've built this system for my brother. He wanted to be able to plug his portable mini-disc player into it, so one of the inputs on the preamp is a screened 3.5mm stereo jack. Apart from the cases, everything is made by my fair hands! ;) I've nearly finished it - I'll post internal pics soon. My brother wanted this as a "classy bedroom amp"...

Goto http://www.rarkovelectronics.co.uk
Click to enter, then on the GainClone link under the Projects heading.

Hope you like them...
Gaz
 
Looks great! Are these custom made cases? Would like to see further details of the construction, inside closeups, etc.

I'm about to finish my "cloning" one of these evenings ;) This will be a test setup to check the sound of the beast and also if I could have both the chips and the psu in one box. I've installed the transformer pretty close to the IC's so wonder if it will make some noise or hum.

The transformer is a rather small one and not the final, just got it for a few weeks. Also, I use only el cheapo parts for the first time. Anyhow, it will hopefully make me able to decide if this simple circuit is really so fantastic, and if so, then I can put more effort into construting a solid case and all the mechanical details.

Good luck with your Gainclone and keep us informed about your progress!

Regards


monguz
 
Hi,
Thanks for your comments. The cases are from Maplins. The manufacturer's part number is AB13. The cases are 6"x4"x2" (wdh). I am only using a 120VA xformer with 25V seconadries. I'm hoping this is going to make the voltage rails droop a couple of volts so that the 35V caps wil be in a safe operating range :att'n:

I will update the pics with better / internal ones soon. You'll find the PSU extremly cramped and the rest of the boxes are empty! I could have put the Two amps and Preamp together but I wanted a classy 4 box system! :cool:

I will give you an idea of sound quality when I finish the PSU cables (The connectors are on back order!)

Gaz
 
hello gaz,

My gainclone is still a rats nest in a cardboard box, I might buy some of those cases on friday afternoon and destroy the rats nest over the week end. Hopefully by this time next week i will have a neat and tidy gain clone.

My set up will be slightly different from yours, I bought two 220VA 2x25V Transformers from RS, i dont think they will fit in the cases you have used, I aslo want to put both channels in one box.

What is the preamp you are using? Is it a passive one?

I just finished Rod Elliotts preamp (project 88) last night, I need to get a box for that too, and some more RCA sockets.

See you later.
Mark:)
 
Hiya Mark,


I swear by those Passive Preamps now!!! I have put my digital one on hold for a while...I run a passive for myself and am building one for this system too.

Your xformers won't fit...Mine are the largest I could get to go in the AB13s...but as a result, the PSU is very underpowered. But I figured that 30-40W (x2) = 60-80W isn't going to hurt the 120VA (W) xformer too much.

I have made extensive use of sticky backed bases and tie wraps so the there are no screws other than the 4 per box holding them together. Very neat - in my opinion. I should also thank Laing Utilities for the cabling, sleeving used and tie wraps! There is a perk to every job! :goodbad:

Gaz
 
I am only using a 120VA xformer with 25V seconadries. I'm hoping this is going to make the voltage rails droop a couple of volts so that the 35V caps wil be in a safe operating range

25 volt secondaries will produce 36 volts (or higher depending on your local mains voltage). The safe way to work out capacitor ratings is to multiply the voltage across them by 1.25 so using caps rated at only 35 bolts is asking for trouble! :att'n:
 
Actually with small transformers < 300 W the voltage rating could go up to 10% above the normal voltage ( this without a large load ofcourse )

but the results are ...

25 *1.1 = 27,5VAC

( 27,5VAC * 1.42) - 0.6V ( using 1 rectifier bridge that is ) = 38,5V :eek:

...

Greetz Rudy
 
Hi,
Well after the bridge rectifier (about a 1.4V drop I would think) the measured outputs were +- 40.1V along the capacitor rails. This dropped to 38V or thereabouts with the load on.

I have reordered the transformers - but with an 18V version this time. I couldn't turn the preamp volume all the way up without the amp over heating, so this should keep things in check!

Gaz
 
Pragmatic HiFi

I love the look of your system. This no nonsense approach is quite appealing. I was wondering if you could give us some more details on the total your total project costs. (just roughly, sans development and failed components would be OK)

Looking forward to more pictures.
 
Hi,
No - nothing is Earthed...
I know it's a safty aspect - but since I don't know earthing regulations very well - I'd probably make them more unsafe. Besides, there isn't that much opertunity to hurt yourself on these! ;)

The cases are from Maplins. The manufacturers code is AB13. If you intend on putting a PSU in these - watch out 'cause they are VERY tight. My PSU is literally bulging at the sides! ;)

Gaz
 
Thanks for posting the parts budget. I think its great to see what can be done with some care and good design sensibilities.

Ive been surprised at how much interest the project boxes have created.

The reason I asked is because its exciting to see that what must be a great sounding system built for not a lot of money.

I think that your system bundled as parts and plans would make a great first audio kit for a lot of people.

Thanks for sharing.

Has anyone asked if you can post pictures of the insides?
 
No - nothing is Earthed...
I know it's a safty aspect - but since I don't know earthing regulations very well - I'd probably make them more unsafe. Besides, there isn't that much opertunity to hurt yourself on these!

Gaz, it's a long shot I agree but not out of the question to get a short between the primary and secondary windings on a transformer and then you could get 240 volts into your amp cases!

The earthing isn't difficult to get right. The earth wire from the mains lead is connected to the PSU case. Connect the earth wire from the transformer and the wire that goes to the amplifier at the same place.

In the amplifier, connect the earth wire to the case and connect that point to the power star point with a 100R resistor with a 22n capacitor in parallel.

I've ordered the AB15 cases from Maplins for my PSU's but am still waiting for them to arrive. The AB13 would be too tight for my transformers.
 
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