What is the sonic impact of SS CCS in tube equipment

[Curly Woods]

What do you all feel is the sonic impact on the sound of tubed systems using SS CSS's? Is there any negative impact to the musicality of the tubed circuits when SS components are added to your ears? I have heard from many that have tried it that it adds a layer of dryness to the sound, but never attempted to try it myself yet. Are they reliable from an electrical stand point? Nothing is ever perfect in my experience, so I am curious what the benefits/tradeoffs are with regards to the overall sound quality.

[SY]

IME, perfectly reliable when designed properly. I use them in my preamp and phono stage and have had exactly zero failures.

If one is looking for the tube circuit to be an effects box, it's not a positive- CCS loading minimizes distortion, removing the second harmonic glaze treasured by many. The important point is to use a good one- the higher the source impedance, the less effect on the circuit. The CCS diodes are pretty awful. Two MOSFETs and three resistors will give you a CCS with astonishing performance.

[Curly Woods]

Originally Posted by SY

IME, perfectly reliable when designed properly. I use them in my preamp and phono stage and have had exactly zero failures.

If one is looking for the tube circuit to be an effects box, it's not a positive- CCS loading minimizes distortion, removing the second harmonic glaze treasured by many. The important point is to use a good one- the higher the source impedance, the less effect on the circuit. The CCS diodes are pretty awful. Two MOSFETs and three resistors will give you a CCS with astonishing performance.

Sy is your CSS shunt or a series circuit? Is there a difference to you between these two types sonically? I want to try them and decide for myself.

[Geek]

When used sanely, I've never had anything but a sonic improvement.
(by sanely, I mean don't load a tube cuircuit up like a discrete op-amp with a CCS on every active lead possible )

Didn't matter if the CCS was in the head or the tail, there were benefits.

Cheers!

[SY]

They're used as plate loads for gain stages and cathode loads for follower stages and diff amp tails. The two-FET circuit I use is shown in the ImPasse article in AX February 2009 (and I think it's been posted here a few times). Walt Jung showed the performance in an article about a month or two later, which validated my impressions.

There was a bipolar version discussed here at length- I think Gregg the Geek was selling some boards, for which I wrote the documentation. The design is based on the CCS circuits shown in Morgan Jones's book, though with a couple of minor tweaks. You can see how the circuit works in the Heretical preamp article on syclotron.com.

One thing to be cautious about- when used as plate loads in a common-cathode voltage amplifier, circuit performance is degraded if there's any cathode degeneration. Either bypass the cathode bias resistor or (better yet) use LED or battery bias.

[Curly Woods]

Thank you both for the inputs.

[Yvesm]

"Sonic impact" as well as "sonically" are to be defined before.
After and only after that, we could chat about how a CCS could alter them !

CCS can also be built with tubes, pentodes or even chokes are . . .

Yves.

[Curly Woods]

Originally Posted by Yvesm

"Sonic impact" as well as "sonically" are to be defined before.
After and only after that, we could chat about how a CCS could alter them !

CCS can also be built with tubes, pentodes or even chokes are . . .

Yves.

I must love 2nd harmonics I guess I had considered a pentode type CSS, but not seen many discussed. I am building a new pair of mono blocks with separate power supply chassis for each channel. Need to breadboard the amplifier stage still to determine if I want to use the CSS. I have read Gary Pimm's page where he talks about pentode CSS. Anyone recommend other examples of a tubed CSS?

Solid state just sounds rather uninvolving to me. There are a few solid state components that I have heard that keep the emotional connection to the music, but as a rule, they are simply just unmoving and unemotional with the music that I prefer.

[analog_sa]

As always in audio it depends. Past experience in replacing simple bipolar transistor CCS as a plate load in a MC step-up pointed in favour of resistor (Shinkoh tantalum) load. More recent experiment of replacing Lundahl plate chokes in a line stage with a DN2540 cascodes was quite surprising, although brief (smoke). Chokes certainly enjoy an advantage of doubling the voltage headroom but recent CCS advances are really impressive. As of using pentodes as CCS it may have some merit but requires much higher voltage supply. Not so attractive.

[Curly Woods]

Originally Posted by analog_sa

As always in audio it depends. Past experience in replacing simple bipolar transistor CCS as a plate load in a MC step-up pointed in favour of resistor (Shinkoh tantalum) load. More recent experiment of replacing Lundahl plate chokes in a line stage with a DN2540 cascodes was quite surprising, although brief (smoke). Chokes certainly enjoy an advantage of doubling the voltage headroom but recent CCS advances are really impressive. As of using pentodes as CCS it may have some merit but requires much higher voltage supply. Not so attractive.

So the chokes serve a similar purpose in the plate as the CSS in the cathode (makes sense). That sounds more in my wheel house of how it might effect the overall sound and still maintain what I like about the tube circuits. This might be better first try for me and my expectations. I like the thought of extra headroom also.
Sometimes I wonder if over regulation rob some of the dynamics from a system. Not that a regulated circuit may not in theory measure better.