[avahifi]

I have been playing with the new Insight+ phono circuits and am thinking they might work very well with the typical lower output moving coil phono cartridges.

I have a Denon DL103 up and running now and sounding very nice and quiet enough too.

All it takes is a couple of resistor value changes to the standard Insight+ (Insight + OPA627AP chips) circuits.

Any of my Insight clients out there with both the Insight phono section and a decent low output moving coil phono cartridge?  I can use some more Guinea pigs.  Give me a call (651-330-9871) if you are able to make a couple of resistor changes on the circuit board yourself and I will tell you what to do.

Thanks

Frank Van Alstine

[Tone Depth]

Hi Frank,

Would this resistor adjustment to the phono preamp circuits, be analogous to the ability to change the output level of the preamp by changing resistors to adjust to a power amplifier sensitivity?

If so, it would seem like you've got some significant gain capabilities with your Insight+ phono preamp circuit (kind of reminds me of the flexibility of my old Kenwood integrated amp with it's phono 2 hi/lo gain switch for selecting moving magnet/moving coil phono cartridges).

[boycephoto]

Hi Frank, 

I know you are asking for a Insight preamp as a guinea pig, mine is an OmegaStar.  Is the circuitry completely different between the two or would a similar change to the phono board be available to the OmegaStar too?  My current cartridge is a Denon DL 103D.  (I am currently using an outboard moving coil phono amp)

Also, my OmegaStar EC has a phase inverter board as well, if I were to update to an Insight  are you still supporting that as an option in the Insight preamp. 
 
Thanks
Dave

[Listens2tubes]

I use a pair of transformers with my Dynavector Karat to boost it's .26mV by 26db which I would prefer to be a bit higher. Would there be a similar scheme for my T8 preamp?

[avahifi]

I need the Insight+ phono section for this tryout.  The tube units do not have enough open loop gain to support the additional closed loop gain necessary, the older solid state units are not quite quiet enough and do not have the new ultra low distortion devices that can support the reduced feedback necessary.

Regards,

Frank Van Alstine

[orthobiz]

Then you can make a tiny board that will fit into my Ultra EC and I can use Spare 1 or Spare 2 to run a second TT with a MC cartridge, right?

Paul

[avahifi]

Yes, this is possible, but with some chassis modifications.  The mounting holes for the second phono RCA jack set will have to be drilled out to accept insulating shoulder washers to isolate the phono ground from direct chassis ground at the back panel, as is done with the normal Special input jack holes.  Then a second Insight moving coil RIAA phono preamp board could be mounted (if the available space is not aready used up with the Tape Buffer option).

However, we have not tested this combination so we do not know if it will be quiet enough in this application yet.  We will test this fairly soon if the overall concept proves to be successful.

Regards,

Frank

[avahifi]

I am running a borrowed Denon right now, from my engineer, on a "you break it you bought it" basis.  I don't dare touch this one.

It is considerably heavier than the Longhorn Grado, I am not sure my tone arm could cope with a Longhorn bar added to the Denon.

Frank

[orthobiz]

Then a second Insight moving coil RIAA phono preamp board could be mounted (if the available space is not aready used up with the Tape Buffer option).

Frank

I am using your phono (Ultra EC) for my main TT and a separate phonostage (Primare R20) in the Special 1 slot to run other turntables (setting my kids up with their own stereos). I do have the Tape Buffer option, is the DVD input better for a phono preamp or is the Special 1 or 2 the way to go? Thanks, Frank.

Paul

[bmckenney]

Is there any difference in the loading your MM circuit has compared to a phono pre that has active MC head amp or a MM with added stepup transformers with this change?  I was wondering if a MC cartridge which can be loading sensitive might not be suited to the circuit.

Bryan

[Minn Mark]

Probably non sequiter (sic) , but I'm using a Sumiko Blackbird into the Insight phono section (no additional pre-pre-amplification). Sounds great !! Plenty of volume control.

M

[avahifi]

I have tried the Denon into the Insight+ moving coil phono stage with both a 100 ohm load and with a standard 47K ohm load and I like the results with the 47K ohm load much better.

Frank

[bmckenney]

I have tried the Denon into the Insight+ moving coil phono stage with both a 100 ohm load and with a standard 47K ohm load and I like the results with the 47K ohm load much better.

Frank

How is the load changed?  With the value of the resistors you mentioned?

Bryan

[bmckenney]

Can you put in a MM/MC switch?

Bryan