Goldpoint SA4M-47 passive 'preamp' winging its way to Marco Towers...

[Macca]

I'm lost here. I appreciate the point of changing from series to shunt but regards the amount of attenuation if you have 47 steps surely there was enough room on the dial for any volume level already? Or did you have to wind it up to 40 or more just to get an acceptable level?

[Marco]

Nope, it wasn't like that, Martin.

It's largely a matter of preference where your optimum listening level is achieved, in relation to the position on the volume dial. I simply like mine, in that respect, to be achieved at around the 8-9 o'clock position, and don't like having to wind the dial(s) round to after 12 noon before anything significant happens in terms of loudness.

I just find that unnatural, and with some low-level recordings, particularly with classical music, you can run out of dial space before reaching the listening level you want!

Also, what I find is that if the gain structure isn't right, and there isn't enough, let's call it overall 'oomph', no matter how much your turn it up, the sound lacks 'balls' and sounds limp and lacking in dynamic attack. There has to be a optimal amount of 'signal strength' (for want of a better description) present in the first place, to be amplified, in order for music to be accurately reproduced.

It's rather like in the old days when recording to tape. In my experience, when setting the recording level on a tape deck, there was always a 'sweet spot' where the sound clicked into place and just sounded 'right'... Not enough level made the the playback sound rather weak and inept, no matter how much you turned the volume up when listening, and too much level resulted in saturation, where conversely no matter how much you turned the volume down, everything still sounded too 'hard' and 'loud'.

Well, if you can understand that concept, it's essentially what I'm applying to the Goldpoint: tuning the playback levels of music in order to hit that same 'sweet spot', so that there is enough 'oomph' present in the signal path, in order for SQ to be optimised, in the same way as I've described with playing back recordings made on a tape deck. Hopefully, that makes some sort of sense now!

Marco.

[awkwardbydesign]

I for one have never seen one of those before... looks interesting. You should try and give it another go for sure.

Unfortunately it has gone! But if I didn't already have a "do everything" back-up amp* I would probably have bought it myself. And if you can get one with the phono stage installed it would be very worth having, IMO.
*http://www.troelsgravesen.dk/JungSon.htm I have split the pre and power sections, with a switch, but haven't replaced the coupling caps yet. I have some, and a pair of different op-amps for the phono stage, just too many other things to do. The LDR pre needs finishing off, I've just bought a new chef's blow torch to flame polish the edges of the red Perspex front. Why do I make my life so complicated?

[Macca]

I understand the idea of gain matching an active pre but not why it matters with a passive pre as there is no gain stage it is just progressive de-attenuation of the fixed-level signal it receives.

If it is just a fetishitic thing about where the volume knob is on the dial then I get that - but how can where the knob is on the dial actually affect the sound adversely unless, as you say. you run out of steps before reaching the required SPL?

[Marco]

Then you obviously don't understand my cassette deck analogy. That last bit, though, is rather important

I'm sorry, but I can't explain it any differently, other than to say if there isn't enough 'level' present in the music signal in the first place, then no matter how much you turn up the volume (on a passive or active preamp), you'll never be able to fully optimise the sound. And the value of resistors used, in that respect (in either a passive or active design) influences things massively!

If you can't 'get' that, then the only thing I can do is try and explain it better in person at NEBO, where perhaps others there able to understand what I'm getting at, will be able to explain it in a technical sense, and maybe that will help you grasp what I'm describing.

Perhaps if Nick is reading, he'll understand what I'm on about and can put it across better?

Marco.

[awkwardbydesign]

how cool... It's great having little nuggets of information like that, Nick...

Or not.

[Macca]

Perhaps if Nick is reading, he'll understand what I'm on about and can put it across better?

Marco.

A brief technical explanation would be appreciated If someone would be kind enough to do so. I get your cassette deck analogy and recall the problem well from my taping days - don't record to low or you will lose the balls. I don't understand how that is related to matching a passive pre-amp, though. It isn't the same thing at all.

[Marco]

It's not the same thing technically, but in my experience it results in a similar thing, sonically. *That* is my point.

Essentially, it's about the 'input level'/loudness [I can't think of a better description] a power amp 'sees', from a preamp (passive or active), to be amplified, and that's a bit like setting the recording levels on a tape deck.

If the 'input level' of the music signal, in that respect is insufficient, then no matter what you do with the volume control afterwards, you'll still end up with a sound lacking in 'balls'...

And that 'input level' of the music signal, which the power amp 'sees', is controlled (at least that's what my ears tell me), by the value of resistors used on the output of the preamp (passive or active), which in my system is how I ended up with a value of 20K, thus allowing me the normal listening levels I desire at around the 8 or 9 o'clock position on the volume controls).

The lower you go in the 'K' value of those resistors, the louder things get, and the higher that value, the less loud it gets (just like lowering or increasing the recording level on a tape deck), thus influencing the playback level available (lower down on the volume controls) and overall sound accordingly.

Therefore, employing the use of, say, 47K resistors would result in there being much less 'loudness level' available, in the early stages of a stepped attenuator, than there would be had, say, 10K resistors been used instead.

Any clearer now? If not, I give up!

Marco.

[DSJR]

This level thing as perceived on a volume control has changed from the 50's and 60's. Back then, volume pots and the overall gain was designed to have optimum listening at TWO THIRDS of the way up, so you have loads of spare travel for lower level listening - look at older Naim stuff using vinyl...

[awkwardbydesign]

This level thing as perceived on a volume control has changed from the 50's and 60's. Back then, volume pots and the overall gain was designed to have optimum listening at TWO THIRDS of the way up, so you have loads of spare travel for lower level listening - look at older Naim stuff using vinyl...

That's how my TVC is set. I would have thought that the closer you run a passive to max, the less there is in the way of the signal to the power amp.