[digi01]

Quote:

Originally posted by AdamZuf can it be cloned exactly? do you have experience with this particular amp?

The part of the circuit is easy to finish, But the JR4556 is difficult to get,I can make the socket of 8 dips.
I feel a difficult one is to make a wooden boxes of neat,exquisite and particular.

I live in BEIJING CHINA,the connection is easy.

 

[AdamZuf]

ok, so what's the part list to make the clone as close as possible to the original?
i want 2 9V batteries, with that XP-7's battery compartment.

 

[stereth]

Quote:

Originally posted by Sovkiller Try to keep the exact values as closer as posible, or you will end with a complete different sounding amp, if it sounds like that, is just becasue of the synergy of the few parts it has in it,

As much as I want to believe that, I doubt 5% on the input cap will be audible. At least in the cmoy, A47, META42, all of the topologies I've dealt with, the input cap is there to block DC offset from the source. Combined with the noise-reduction resistor, B in the schematic above, it unfortunately forms a high-pass filter. The cmoy uses 0.1uF to get a corner frequency of 16Hz. A 5.0uF cap moves this corner frequency to 0.3Hz.

Anyway, it looks like those Solen caps have a tolerance of 5%. Most caps are 10% or more.

 

[Sovkiller]

Quote:

Originally posted by stereth As much as I want to believe that, I doubt 5% on the input cap will be audible. At least in the cmoy, A47, META42, all of the topologies I've dealt with, the input cap is there to block DC offset from the source. Combined with the noise-reduction resistor, B in the schematic above, it unfortunately forms a high-pass filter. The cmoy uses 0.1uF to get a corner frequency of 16Hz. A 5.0uF cap moves this corner frequency to 0.3Hz. Anyway, it looks like those Solen caps have a tolerance of 5%. Most caps are 10% or more.

Maybe is not in fact, but this is not the point, if the exact same exist, and is available, and is a pretty good one, why not use the same, you want a clone, well the clone is withthe exact same parts....otherwise is similar amp, with a similar sound....

 

[Sovkiller]

I don't think he needs the box, anyway a metal one, should be better as the shielding and isolation from RF and RMI, should be better, they paint the interior of the wooden case with a copper alloy paint orsomething similar, to get the shielding, get a Lansing case and it will look sharp and sound superb.....find out about the grounding also.....

 

[AdamZuf]

Sovkiller,
we are making an clone, right.. but with my almost 0 knowledge of mine in electronics, i can assume that choosing a very little different input caps. the difference from one source to the other will be greater, probably. am i correct?

 

[Sovkiller]

Maybe you are right on that, Adam it will be your amp not mine, decided what you believe is right for you, but the exact one is available, and cheap, $2.45 a piece (plus shipping), if you want I can get them for you, and mail it to where ever you want, to be on the safe side, just PM me..........play safe man, if you want the same exact sound, those gurus, always do a little of black voodoo magic, with the parts, and some snake oil, and some bat wings, in a big pot, with a few drops of pro-gold, before assembling the amps.....honestly is hard to believe that this simple circuit, with less than 10 parts in it, sounds the way people are raving, while others are complaining on the PPA hiss....or mids, or whatever...(a more serious design IMO)

 

[digi01]

the part list:

VOLpot:
100K*1;

R:
100k*2;
121K*2;
464k*2(This is non-standard resistance, need series-parallel connection to be gotten.or used 470k, will improve slightly to gain. 4.84dB/4.88dB.)

C:
112nF*2;
5uF*2;

PSU:
battery compartment,for two 9V batteries;
LED*1;
switching*1;

IN/OUT:
RCA*2;
headphone jack*1;
Socket of 8 dips*1;

OTHER:
wooden boxes*1;
JR4556*1;
CABLEs & PCB.

 

[Sovkiller]

The picture of the amp board with the parts, is on that same site I get this one, maybe you could read the right values of the R that is not standard, maybe is a mistake of that guy, but he was the only one who had rip off his amp to show you what is inside....so at least I trust him, take a look:

 

[AdamZuf]

so.. are all of the parts available? from how many vendors do these have to be ordered from?

 

[digi01]

Thank you Sovkiller.Careful observation, the resister to the negative feedback of ground.It color specification is "yellow\blue\yellow\orange\brown,so it resistance value is (464*10*10*10=464K +-1%).
So I think that his drawing is accurate.

 

[Sovkiller]

Well if is there, the value exists, just that we have to find out where.....

 

[GWN]

Mouser.com has all the resistance value you need including the 464K, some 55 different ones. Here is an example, Vishay/Dale 0.1% precision metal film 464K, Mouser part number 71-RN55C4643B

Actually, all the parts except the Solen caps, Radio Scrap potentiometer and wood case are available from Mouser including the opamp, Mouser part number 513-NJM4556AD . The caps sold by Parts Conexxion and Madison will work but are the bigger 400 Volts vs the 250 Volts used in the RA-1. You can find 250V Solens 5.1uf at http://www.solen.ca/ Part number PA510

 

[Ajit]

I have a question for you since you built a RA-1 clone. How is the pot wired? With one end to the ground and the wiper to the coupling caps? Reuben's schematic shows them as resistors. Thank you!

 

[Sovkiller]

Quote:

Originally posted by GWN Mouser.com has all the resistance value you need including the 464K, some 55 different ones. Here is an example, Vishay/Dale 0.1% precision metal film 464K, Mouser part number 71-RN55C4643B Actually, all the parts except the Solen caps, Radio Scrap potentiometer and wood case are available from Mouser including the opamp, Mouser part number 513-NJM4556AD . The caps sold by Parts Conexxion and Madison will work but are the bigger 400 Volts vs the 250 Volts used in the RA-1. You can find 250V Solens 5.1uf at http://www.solen.ca/ Part number PA510

Madisound ones is the exact same ones: 5.0uF 250volts