New toy - Jolida JD9 MKII

[Bigman80]

An earphones session proved useful tonight, I swapped the load to 1k and I think it got better! I'll need to have a listen through the speaker's obvs but so far so good. I think for the money, this is a bit of a bargain!

So, capacitors. I can't find 4.7uf 63v polypropylene caps to replace the orange drop type. Any ideas? I don't want to swap values as I want to keep things as original as possible but with better components.

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[RothwellAudio]

I felt a little moment of "i wonder what thats like"

So I've ponied up on a whim and bought it.

Heres some detail which as yet doesnt mean much to me :


INTIMATE AUDIO UPGRADE:- (carried out July 2017)
The ECC83-Retro produces the warm detail and harmonically rich midrange that made the Mullard sound so famous. The valve has been designed to have a smooth harmonic slope which gives a warm crunch. The Cryo treatment gives greater depth and clarity to the valve sound, sweetening the highs and tightening the lows .The Cryo also adds a crisp bite to the valve making this the ideal choice to add crunch and punch to your sound. )
Specifications:-


MC High: 85dB, 0.5mV to 1.5mV

MC Low: 95dB, 0.25mV to 0.5mV

Input resistance: 100 ohm, 300 ohm, 1Kohm, 47Kohm

Input capacitance: 47pF, 100pF, 150pF, 220pF

There are some things about the Jolida phonostage that bother me. First is the quoted gain of 85dB and 95dB. That's totally insane. Typical MC gain requirements are about 60dB, maybe 70dB at the top end. Why would you want 35dB more? I'm assured via another forum that the figures are incorrect and the gain is a lot less. But that bothers me even more. I'd be uncomfortable buying a product made by a company that can't even measure gain.
Secondly, the phonostage is marketed as a valve (or tube) phonostage with no mention that the front end is an op-amp, so about half of it is solid-state, not valve. I'm not a valve purist but I wonder if the valves are there for marketing purposes as much as anything else.
BTW, "a warm crunch"? I'm not sure that hi-fi is supposed to add crunchiness to anything. I suspect that description is taken from a sales pitch aimed at the guitar amp market. Of course, a guitar amp is a totally different beast to a phonostage.
There's a huge thread all about modifying the Jolida here:
http://audiokarma.org/forums/index.p...thread.344317/

Anyway, if you got it at a reasonable price and it sounds good, that's all that matters in the end. What is it like in terms of signal-to-noise ratio?

[walpurgis]

I have doubts about 'cryo treatment'. The low temperature extremes contracting the valve glass envelope to the extent that the seal to the pins is compromised?

[Bigman80]

Hey Andrew, yes youre quite rights. It's about 100% opamp driven phonostage with valves after the effect but valve rolling yesterday showed that they do make a difference. I presume the crunch part of the description is a bit of spiel as they are really very fluid. I think you're right about the guitar aimed marketing. They do provide excellent clarity and resolution. I think more can be achieved though but at £18ea they are great value.

I'm sure there are warmer valves but in reality these are very good although my valve experience is limited. Alan's is much more thorough and they impressed him.

There is a LOT of gain and yes I agree, I am not entirely sure why. It's not noisy though, which is impressive.

Whilst I agree that

A) if the manufacturers can't measure accurately then it would sound alarm bells

B) marketing it as a Valve stage is naughty

At some point your ears must take over from the spec sheet and I'm very glad i bought it.

The variable dip switches are good too and they are great for the learning curve which I want to take.

If you fancy a listen, you're more than welcome to pop in!

Oliver.



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[struth]

I have doubts about 'cryo treatment'. The low temperature extremes contracting the valve glass envelope to the extent that the seal to the pins is compromised?

be more likely the pins will contract more than the glass, although the end result would be similar i guess. pyrex glass has a small coefficient compared to metal

[Bigman80]

be more likely the pins will contract more than the glass, although the end result would be similar i guess. pyrex glass has a small coefficient compared to metal

Isn't something to do with molecular realignment of the metal?

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[Firebottle]

Secondly, the phonostage is marketed as a valve (or tube) phonostage with no mention that the front end is an op-amp, so about half of it is solid-state, not valve.

Hi Andrew,

The gain figures alarmed me when I first saw them as well. The actual topology is 3 op-amps and 1 valve per channel. I guess the 3 op-amps are being 'run' conservatively, that is with fairly low gain figures for each. The first op-amp is a very low noise LT1028. It looks as if the RIAA is split with part being done passively and the other part via feedback on the 3rd chip, I hope to confirm this at a later date.

Rather more than half solid-state then, the valve stage is arranged as an SRPP, again with a low gain figure of about x 4.5.

[RothwellAudio]

Isn't something to do with molecular realignment of the metal?

Yes. When I first heard about cryogenic treatment I did think it was audiophile mumbo-jumbo but when I looked into it I discovered that it's a widely used treatment in the materials science industry similar to (the converse of?) heat treatment, used for hardening metals. I'm sure there's more to it than that and I may have misrepresented it However, how that relates to valves and the effects on audio performance I don't know.

The gain figures alarmed me when I first saw them as well. The actual topology is 3 op-amps and 1 valve per channel.
Rather more than half solid-state then, the valve stage is arranged as an SRPP, again with a low gain figure of about x 4.5.

At least they used a low-noise op-amp. I'd be cautious about "chip rolling" willy-nilly. Actually, I tried rolling an op-amp once and found they're just not the right shape for rolling
So, it's mostly op-amps with a tube thrown in for marketing. Am I the cynical one or are they?

[Bigman80]

Yes. When I first heard about cryogenic treatment I did think it was audiophile mumbo-jumbo but when I looked into it I discovered that it's a widely used treatment in the materials science industry similar to (the converse of?) heat treatment, used for hardening metals. I'm sure there's more to it than that and I may have misrepresented it However, how that relates to valves and the effects on audio performance I don't know.

At least they used a low-noise op-amp. I'd be cautious about "chip rolling" willy-nilly. Actually, I tried rolling an op-amp once and found they're just not the right shape for rolling
So, it's mostly op-amps with a tube thrown in for marketing. Am I the cynical one or are they?

I think it's a bit harsh to think of the Jolida like that, especially when it sounds like it does. It's a very good unit. It is what it is. A hybrid of sorts. I like it.

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[RothwellAudio]

I think it's a bit harsh to think of the Jolida like that, especially when it sounds like it does. It's a very good unit. It is what it is. A hybrid of sorts. I like it.

Yes, no offence intended. It's probably me who's the cynical one - must lighten up