The Marco-boy main system, as of August 2020

[Marco]

Ideally all equipment we use, should match the level of the source media we purchase or use.

If used with a passive, then there is no need to change the sensitivity with a 306, as it then is perfectly suited to line level output from almost every known source component. This is because the RMS level in media we use rarely exceeds 350mv , The source component equipment can have, and usually does have much higher specification, but the media itself ie CD's Flac files etc in my experience never exceeds the 350mv mark, see attached which is a flac file being read by Audacity, the RMS level is in light blue

Level changes away from the source level, appeasing other equipment's lack of sensitivity,( IMO then on entirely the wrong path ) is then neatly avoided.

Cheers, Chris! Btw, I hope you're well and staying safe, mate

Hey, at long last I'll be able to try your LDR, which might match really well with the 306... On that note, and just to clarify, in terms of the connections at the rear of the unit... I'm presuming that the two phono sockets separated from the rest, on the far right, are the outputs to the power amp?

Also, of the other three sets of sockets to the left of that, what are the differences, if any, and which one should I connect to my CD player? Furthermore, in terms of the input selector switch, it just seems to continually click round, without limit, so how do you know which inputs it's activating, other than simply listening for when the sound comes through or not?

Marco.

[Light Dependant Resistor]

Hi Marco
Yes safe and well, trust the same there for you and your partner.

Yes RCA pair further from the 3 inputs are the outputs, The input switch selecting the series pair anodes , is a bit different to normal in that the needed
contact, is made prior to falling into its rest position. the rest position being off. Seen here with a internal image its a well made switch.

Input 1 which is the RCA pair closer to the output is then selected with the front panel switch furthest to the left , but then allowing to be just off the off rest position.
input 2 then follows the next rest position.

Looking forward to how it goes. I have 24 boards in production so will send you an updated main board before Xmas.

Cheers / Chris

[walpurgis]

According to the info Geoff stated in post 453, it's 375mV, so does that mean that the 405-2 is less or more sensitive than the 306?

Marco.

A bit less.

[anthonyTD]

Input Sensitivity of the copper amps [depending on the feedback position] around 500mv.

Cheers, Geoff. However, I've no idea what the likely result will be of using it with the Croft 'as is'... Do you think it would have too much or not enough gain? I know you don't know the figures, but just your gut feeling?

No idea what the input sensitivity is of my Copper amp, so that's one to ask Anthony. Like I said though, a mate brought round his 405-2s and they were fine, so is the gain on the 306 different from that on the 405s?

Marco.

[Marco]

Cheers, mate (and Geoff), so that's interesting... The *lower* the figure, the higher the sensitivity? So if the 405-2s are 500mV, as Barry says, that'll explain why Ian's worked fine with the Croft, as it's the same as the Copper amp

So is the 125mV of difference in sensitivity between the 306 and the 405s (with the the former being 375mV) likely to be a major issue?

Marco.

[Marco]

Hi Chris,

Glad that you guys are safe and well. NZ seems to be one of the safest places to be, and have dealt with the virus pretty well

All noted, except for the input switch selector, which appears to just go round and round with no 'rest position'... Normally input selectors only have a small number of available steps/positions, and 'lock' either way at the end of those.

Therefore, in that respect, I don't understand what you mean by 'furthest to the left'...?

In terms of boards, I still have the first ones you sent me lying there. I've forgotten how to fit them now, but will have a look. If it's all a bit too complicated though, baring in mind that I am *a total numpty* when it comes to these things, I may just return the unit to you, along with the 'old boards', for you to fit the latest ones, if that's ok?

Marco.

Hi Marco
Yes safe and well, trust the same there for you and your partner.

Yes RCA pair further from the 3 inputs are the outputs, The input switch selecting the series pair anodes , is a bit different to normal in that the needed
contact, is made prior to falling into its rest position. the rest position being off. Seen here with a internal image its a well made switch.

Input 1 which is the RCA pair closer to the output is then selected with the front panel switch furthest to the left , but then allowing to be just off the off rest position.
input 2 then follows the next rest position.

Looking forward to how it goes. I have 24 boards in production so will send you an updated main board before Xmas.

Cheers / Chris

[Light Dependant Resistor]

Hi Chris,

Glad that you guys are safe and well. NZ seems to be one of the safest places to be, and have dealt with the virus pretty well

All noted, except for the input switch selector, which appears to just go round and round with no 'rest position'... Normally input selectors only have a small number of available steps/positions, and 'lock' either way at the end of those.

Therefore, in that respect, I don't understand what you mean by 'furthest to the left'...?

In terms of boards, I still have the first ones you sent me lying there. I've forgotten how to fit them now, but will have a look. If it's all a bit too complicated though, baring in mind that I am *a total numpty* when it comes to these things, I may just return the unit to you, along with the 'old boards', for you to fit the latest ones, if that's ok?

Marco.

It is a 11 contact position switch, but only the first three contacts are used, as it was not supplied with a stopper position for 3 inputs ... But the front panel left knob should turn to the left and reach a point where it stops, If you want to try it before returning here, establish the stop position furthest to the left , then as the switch reaches a point midway between getting to the next rest spot that will be input 1... it then proceeds like into a little valley the rest spot , then out of that valley is input 2 and proceed on for Input 3. its quite a nice switch as it really contacts vs other switches that don't contact as well.

Certainly pack it up and return here, for updating, I will send you a PM with my details.

Cheers / Chris

[Marco]

Hi Chris,

It is a 11 contact position switch, but only the first three contacts are used, as it was not supplied with a stopper position for 3 inputs ... But the front panel left knob should turn to the left and reach a point where it stops...

That's that point mate, it doesn't! Just turns round and round, and round, whilst clicking at certain points., so it's impossible to determine the start or end point, or which input you're on...

Anyway, thanks, I'll reply to your PM later - got to go out soon.

Marco.

[DarrenHW]

Looks like you're ok on the sensitivity front then. Sorry for any confusion caused. It was a major improvement for me when I adjusted the 405's, but it was so long ago I can't remember from what I adjusted it from or to...

[Marco]

Hi Darren,

What about the fact that the 306 has a sensitivity of 375mA, and therefore is more sensitive than the 405s, won't that be an issue, or is the difference not large enough to worry about?

Marco.