Phono preamp in HK 3490

[05SRTguy]

Has anyone seen a review of this receiver that specifically talks about the phono preamp that is built in? I want to know more about it, but I can't find anything.

 

[lini]

From the service manual you could see that the MM section is a pretty simple, single-stage, opamp-based design with the (re-)equalisation being done in the feedback loop. Pretty much the usual approach in that class today, using a fairly decent opamp (NJM2068), though. Input capacity apparently ~ 200 pF. A bit much EMI blocking for my taste, though - but that's also pretty usual nowadays.

On the whole it would seem usable, but nothing to write home about - and most probably it'll be a bottleneck for good carts with high quality needles.

Greetings from Munich!

Manfred / lini

 

[05SRTguy]

Would I benefit from an outboard Pre-amp? And how much would I have to spend to notice a difference?

 

[lini]

Hard to tell, 'cause I don't know which cartridge you currently use and which you might already be allured to try in the future. Depending on that, another alternative could also be to modify the existing phono section for better performance, which can be a lot cheapet cheaper, especially if one can do it oneself.

To give you an example, the Marantz PM7000/8000/7200 integrated amps already have pretty decent phono sections, but especially the European models version are completely crippled by an excessive input capacity of > 1150 pF. So in that case basically all one needs to do (or have one) is to remove the two caps per channel that are responsible for that excess and instead replace these by one or two caps per channel with suitable values. If one can do it oneself and doesn't factor in the time/work, a matter of roundabout 5 Euro or less for parts and shipping. Whereas a new phono stage in comparable class would be roundabout fifteen to forty times as expensive. Or even more, if one would mod the integrated phono section a bit further - 'cause with a couple more inexpensive part swaps, one can easily squeeze another quality step or two out of that design.

Greetings from Munich!

Manfred / lini

 

[CasualKiller]

I had one of these running a pair of Klipsch KG4's in the basement, I would describe the phono as "functional".

 

[catman]

G'day all. Lini: input capacitance of that enormous value? Wow, that's unbelievable but I can believe it anyway!

Another bizarre EU 'emc' requirement? Probably! Regards, Felix aka catman.

 

[lini]

Felix: Yup, there are some really weird examples. Another rather odd one would for example be the initial version of the Teac AG790 receiver - with just 6.5 mV sensitivity/31 dB gain, ca. 22 kOhm and 830 pF. In the later variant with suffix "A" they still stuck to the low gain and input impedance, but at least swapped the NJM4558 for an NJM2068 and reduced the capacity to 380 pF (granted, most often still suboptimal, but at least not totally crazy...). Interestingly enough, they use pretty much the same approach, also based on a 2068, in their AG980, but with more sensibly chosen values... So it's not like they wouldn't know how to do it right (or at least quite a good bit better...).

Greetings from Munich!

Manfred / lini

 

[iramegdal]

Hard to tell, 'cause I don't know which cartridge you currently use and which you might already be allured to try in the future. Depending on that, another alternative could also be to modify the existing phono section for better performance, which can be a lot cheapet cheaper, especially if one can do it oneself.

To give you an example, the Marantz PM7000/8000/7200 integrated amps already have pretty decent phono sections, but especially the European models version are completely crippled by an excessive input capacity of > 1150 pF. So in that case basically all one needs to do (or have one) is to remove the two caps per channel that are responsible for that excess and instead replace these by one or two caps per channel with suitable values. If one can do it oneself and doesn't factor in the time/work, a matter of roundabout 5 Euro or less for parts and shipping. Whereas a new phono stage in comparable class would be roundabout fifteen to forty times as expensive. Or even more, if one would mod the integrated phono section a bit further - 'cause with a couple more inexpensive part swaps, one can easily squeeze another quality step or two out of that design.

Greetings from Munich!

Manfred / lini

To resurrect an old thread, how much would I need to spend on a separate phono stage to notice the difference in SQ, if using an Audiotechnica AT95 with Vividline stylus or an Ortofon OM5e or OM10 cart? I also have an HK 3490.