Is there a phono stage manufactured that allows impedance/capacitance adjustment without add gain to the signal so it can be connected to a phono input?
Question Silly Question about phono stages
- Thread starter vinyl4ever
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A question.
I assume the problem you want to address is that you want to be able to change the capacitive/resistive load, but already have a phono input on an amplifier that does not offer this facility.
Short answer is 'no'. The existing built-in phono stage will already have capacitive and resitive loading, so you could ony make both/either of these greater, not less. In the case of capacitance, the standard amount is usually more than enough, when you add in the capacitance of connecting cables. The standard resistive load is normally 47k ohms for moving magnet inputs and changing this won't have any effect on the (vast) majority of MM cartridges. For moving coil inputs it's normally either adjustable, or set at 100 ohms. There are some MC carts that are happier at different loads, but as above, if it's already 100, you can't do anything externally to make it anything other than somewhere between 0 and 100. It would usually be possible to get inside and change certainly the resistive load, but capacitive may be harder.
You can't just add an external low-gain phono stage to a phono input, as both of them will add RIAA correction, so you'll mess up the sound. What you can do, of course, is to add a fully-adjustable external phono stage and connect it to an amplifier's line input.
Short answer is 'no'. The existing built-in phono stage will already have capacitive and resitive loading, so you could ony make both/either of these greater, not less. In the case of capacitance, the standard amount is usually more than enough, when you add in the capacitance of connecting cables. The standard resistive load is normally 47k ohms for moving magnet inputs and changing this won't have any effect on the (vast) majority of MM cartridges. For moving coil inputs it's normally either adjustable, or set at 100 ohms. There are some MC carts that are happier at different loads, but as above, if it's already 100, you can't do anything externally to make it anything other than somewhere between 0 and 100. It would usually be possible to get inside and change certainly the resistive load, but capacitive may be harder.
You can't just add an external low-gain phono stage to a phono input, as both of them will add RIAA correction, so you'll mess up the sound. What you can do, of course, is to add a fully-adjustable external phono stage and connect it to an amplifier's line input.
Hi and thanks for the reply.
My amp has adjustable 2× phono inputs (althought being over 40yrs old could possibly do with a service.)
These offer the ability to change both the impedance and capacitance however using MM carts I can't say I hear much difference throughout the range.
I only ask as being a little OCD ( OK quite a lot) I wanted to keep the TT connected to the amp via the photo inputs rather than using a spare tape in function.
Many thanks
Stewart
My amp has adjustable 2× phono inputs (althought being over 40yrs old could possibly do with a service.)
These offer the ability to change both the impedance and capacitance however using MM carts I can't say I hear much difference throughout the range.
I only ask as being a little OCD ( OK quite a lot) I wanted to keep the TT connected to the amp via the photo inputs rather than using a spare tape in function.
Many thanks
Stewart
With MM cartridges, you’ll mostly hear subtle changes to the high frequency sounds with capacitance changes, but it’s dependent to some extent on the individual cartridge.
A significant majority of phono inputs aren’t changeable because it’s far less difference than, say, tweaking a Treble control.
A significant majority of phono inputs aren’t changeable because it’s far less difference than, say, tweaking a Treble control.
Cracking amp , very musical
I have a pioneer SA 706 from the same era ..
A slight aside. A few years I did minor fettling - cap replacement - on the phono stage of a Technics SU-8080. About the same age as your amp.
There was a very positive difference to the sound. But you may not want to fettle.
If your amp hasn't been serviced it may be worthwhile.
Yes I love it. Have been thinking about finding someone to give it its 40yr service.
It's probably worth it. I did the usual - DC offset and bias. Barely needed touching tho'.
Sold it to someone in the pub - no, really. Admittedly for over twice I bought it for...
When I took the 706 in for a service and to have new bulbs fitted in VU meters the guy said it didn’t need anything doing to it and the components where as good as you could get ..
Trouble is I don't like moving it too often as it's about 20kg, I have it on the bottom shelf of a double wide TV / AV RACK and it has bent the metal box work
The 50k is normal, but the resistive loading shouldn't really make any dfference. Ortofon suggest 150-300pF loading for the 2M series. However, the cables will have capacitance and I'd normally guess at about 100pF for this, so the 300pF is slightly high. Shouldn't be any issue though, but it may roll off the top end very slightly. OTOH, you don't want it too low, as that can cause some losses in the upper mids.
Either way, whatever sounds right is what's best. There is no potential to do any harm, so just choose what you prefer the sound of.
Either way, whatever sounds right is what's best. There is no potential to do any harm, so just choose what you prefer the sound of.
I'll beg to differ slightly. The aforementioned Technics amp had 2 settings for resistive load - 47k and 33k. The 33k certainly didn't sound right, so I'd leave the OP's at 50k.
I was using an Ortofon 2M Bronze.
I'd certainly try a lower cap load tho', but if the OP prefers it at the value set, then fair enough.
As mentioned, re-capping the phono stage brought a definite improvement in detail and general funkiness.
Lowering the cap I found the treble a little muffled, maybe it's my ears? But definitely had more clarity in the mids at this value
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