The price is right....or is it?

[Marco]

Yup, we need more Glenn Crofts in the audio industry!

Pity, though, he doesn't rate stepped attenuators or polypropylene caps much (both of which have been fitted inside my modified Charisma, to great sonic effect)....

To my ears, they're simply more accurate than their carbon-potted or electrolytic counterparts, and therefore one simply hears more of what the circuit can do! There are no downsides I can detect, unless one simply seeks a more coloured or 'warmer' sound.

Marco.

[Firebottle]

Can't understand why he doesn't rate polyprops. To my mind they are essential as are the ilk of polystyrene or similar/better for the eq components.
Both of these types are available for pin money compared to the exotica........

As far as I can tell Glenn uses polyester types, I stand to be corrected if otherwise.

All interesting stuff, I've now got ideas to improve mine even more,

Alan

[Marco]

Lol - nice one...

I guess that at the end of the day commercially produced equipment is always going to be built to a price, which is a restriction a bespoke design doesn't need to have.

What's your view on quality stepped attenuators versus pots? For me, I've yet to hear ANY pot sound as accurate as the best available stepped attenuators, but then maybe that's why Glenn likes using his dual-mono doo-dahs...?

Marco.

[Firebottle]

For convenience and low cost a motor driven pot, but for precision definitely a stepped attenuator.

The dual mono pots is sure an 'inexpensive' way to achieve tracking plus balance, it's all down to the operator.


Now.........what other functions can be hoiked onto the consumer to save cost

Alan

[nat8808]

For convenience and low cost a motor driven pot, but for precision definitely a stepped attenuator.

The dual mono pots is sure an 'inexpensive' way to achieve tracking plus balance, it's all down to the operator.


Now.........what other functions can be hoiked onto the consumer to save cost

Alan

Some kind of organic chemical power supply, probes attached to muscle cells?

Running your finger along the groove of a record and singing the tune down a tube to your now empty speakers?

[nat8808]

On the other hand, a balance control often involves the signal going through two pots of some kind or at least a secondary shunt? (p.s. I've no idea how people implement balance controls).

I've what looks like a home-made valve pre kit from the 80s and originally it had dual mono volume controls but the owner then reconfigured it for convenience to stereo and balance - essentially just wired one pot in series with the other as per the different functions dictate. Sonically daft IMO. DNM has the same dual control philosophy - less circuitry or few components in the signal path at the expense of convenience.

On stepped v continuous controls: You can't really implement dual controls which double as a balance control with stepped attenuators without giving such a rough balance control as to be fairly useless - it simply wouldn't pass the reviewers tests without being shouted about etc etc.

So to use a stepped control and be commercially viable, they'd have to also include a balance control. Therefore sonically the stepped + continuous balance control would have to outperform a good continuous on it's own. i.e. not just a straight comparison

[Mr Kipling]

No but then I don't need it as my eq is not the one in error.
I found the published results from Stereophile and the measured curve is quite wrong: http://www.stereophile.com/content/c...r-measurements

Marco - I found an earlier posting saying your Charisma was measured flat to 100KHz by AnthonyTD, I assume that includes the RIAA so no worries

Alan

No. What I meant was have you tried a 4-pole filter just out of curiosity. But I would presume the answer is no.

[Marco]

As far as I can tell Glenn uses polyester types, I stand to be corrected if otherwise.

Cool - at one time he had a thing for Jensens.

My fav (coupling) caps are the SCR Teflons, sold by Hi-Fi Collective, or V-Caps!

Marco.

[Firebottle]

Well I've finally found time to try the Croft EQ network, with some very interesting results.

If you recall the Stereophile plot of RIAA error for the Croft Phono integrated:



I have used the EQ network found in the 25R but installed in my Firebottle phono circuit, using different and higher gm valves to those that Glenn uses.
I have adjusted the series resistor to allow for the differences in the first stage source impedance to level the playing field.

I get the bass lift under 100Hz, but do NOT get the treble drop off as shown above, in fact the hf performance is excellent.
Whether the difference is down to the use of ECC83s in the Croft integrated I don't know but I have a certain regard for Glenn's EQ network as it makes use of readily available capacitor values, namely 10 nF and 1 nF.

The loss through the network is a little higher than the traditional all in one passive network, but when using high gain valves that is of little consequence.

All good stuff,
Alan