The larger you make R14, the more sensitive the DC voltage at the collector of Q9 becomes to tolerances and temperature variations. I don't really know how high you can go before getting into trouble. For signal handling, you would like the DC voltage at the collector of Q9 to be somewhere halfway between the supply and ground.
Measuring the response with a test record frequency sweep sounds like a good idea.
Measuring the response with a test record frequency sweep sounds like a good idea.
So, I bought and installed some 330uF caps for C4.
Immediately, this has sorted out the thin bass problem I was having!
Thank you Rayma for initially looking at the circuit and quickly identifying an obvious bottleneck. Getting around 1dB back at 30Hz has had a huge benefit. Hopefully there is still enough filtering elsewhere for record warps etc.
So there is no need to change R14 for a higher value from the way it now sounds. Thanks for this other suggestion all the same Marcel.
The only couple of issues I’ve got now is I was careless when ordering the caps as they are too tall to fit the case cover back on! The caps are 31 mm tall.
So I’ll have to get some different caps. 20 mm tall is about the max height possible.
So I am running without the top case for now. The caps I’ve put in are Nichicon Muse KZ 330 uF 50V. As well as the bass extension being improved, they make the sound warmer and smoother than the generic original caps, but perhaps it’s a little too warm.
Also perhaps the top end has slightly less speed than before, and I guess this might be caused by using a bigger value electrolytic coupling cap (330uF vs 47uF). I could try bypass caps but they can be hard to tune and rarely give a coherent my result in my experience.
So I’ll stick to single caps, - I might go down to 220uF to retain a bit more speed in the top end. Hopefully the low end will still be enough, - 220uF is not a big difference in value to 330uF in terms of the bass corner frequency.
Does anyone have any recommendations for a cap brand/model that is a bit less warm than the Nichicon KZ?
Elna Silmics are also pretty smooth sounding and so are Nichicon FG and Nichicon Muse UES bipolars, so perhaps something else.
How about Elna Cerafine? Or has anyone else got another recommendations?. Failing that I guess I could buy a few different pairs of generic caps and try those. They might give a more lively result.
I did also buy some 22uF tantalum caps to change the 10uF Input caps but it probably isn’t needed. Changing C4 for a bigger value has made a massive difference to the bass. Just need to fine tune the C4 cap type to taste now.
Thanks again for your help guys. 👍👍
Immediately, this has sorted out the thin bass problem I was having!
Thank you Rayma for initially looking at the circuit and quickly identifying an obvious bottleneck. Getting around 1dB back at 30Hz has had a huge benefit. Hopefully there is still enough filtering elsewhere for record warps etc.
So there is no need to change R14 for a higher value from the way it now sounds. Thanks for this other suggestion all the same Marcel.
The only couple of issues I’ve got now is I was careless when ordering the caps as they are too tall to fit the case cover back on! The caps are 31 mm tall.
So I’ll have to get some different caps. 20 mm tall is about the max height possible.
So I am running without the top case for now. The caps I’ve put in are Nichicon Muse KZ 330 uF 50V. As well as the bass extension being improved, they make the sound warmer and smoother than the generic original caps, but perhaps it’s a little too warm.
Also perhaps the top end has slightly less speed than before, and I guess this might be caused by using a bigger value electrolytic coupling cap (330uF vs 47uF). I could try bypass caps but they can be hard to tune and rarely give a coherent my result in my experience.
So I’ll stick to single caps, - I might go down to 220uF to retain a bit more speed in the top end. Hopefully the low end will still be enough, - 220uF is not a big difference in value to 330uF in terms of the bass corner frequency.
Does anyone have any recommendations for a cap brand/model that is a bit less warm than the Nichicon KZ?
Elna Silmics are also pretty smooth sounding and so are Nichicon FG and Nichicon Muse UES bipolars, so perhaps something else.
How about Elna Cerafine? Or has anyone else got another recommendations?. Failing that I guess I could buy a few different pairs of generic caps and try those. They might give a more lively result.
I did also buy some 22uF tantalum caps to change the 10uF Input caps but it probably isn’t needed. Changing C4 for a bigger value has made a massive difference to the bass. Just need to fine tune the C4 cap type to taste now.
Thanks again for your help guys. 👍👍
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Hi,
There is no clear answer which capacitor will be right for you, which sound will be good for you. I suggest you buy several types of capacitors from a reliable source (Mouser, Farnell, RS Components and others), different manufacturers, unipolar and bipolar, tantalum. In place of the capacitor on the PCB, you can use the RS Stock No.:826-7191 strip, only £1.76 and fun for a month.
I think that currently it is not possible to buy a new and original Elna Cerafine capacitor, only products from authorized stores should interest you.
There is no clear answer which capacitor will be right for you, which sound will be good for you. I suggest you buy several types of capacitors from a reliable source (Mouser, Farnell, RS Components and others), different manufacturers, unipolar and bipolar, tantalum. In place of the capacitor on the PCB, you can use the RS Stock No.:826-7191 strip, only £1.76 and fun for a month.
I think that currently it is not possible to buy a new and original Elna Cerafine capacitor, only products from authorized stores should interest you.
That doesn't make any sense, the properties of C4 should have no effect at the top end as the 220R resistor is in charge in that regime... Making sure the supply is thoroughly decoupled is probably worth investigating.
Wouldn't usually do this, but it does appear there is room with the cover on, to place them horizontally against the board
and bend the leads downward into the pcb pads. The two caps could also be tied together for more stability.
If possible use these, in order of preference:
https://www.digikey.com/en/products/detail/nichicon/UES1V331MHM1TN/7701978
https://www.digikey.com/en/products/detail/nichicon/UES1E331MHM/2597894
https://www.digikey.com/en/products/detail/nichicon/UES1V221MHM/2597912
https://www.digikey.com/en/products/detail/nichicon/UES1E221MHM/2597892
and bend the leads downward into the pcb pads. The two caps could also be tied together for more stability.
If possible use these, in order of preference:
https://www.digikey.com/en/products/detail/nichicon/UES1V331MHM1TN/7701978
https://www.digikey.com/en/products/detail/nichicon/UES1E331MHM/2597894
https://www.digikey.com/en/products/detail/nichicon/UES1V221MHM/2597912
https://www.digikey.com/en/products/detail/nichicon/UES1E221MHM/2597892
Ah I see Thanks for this useful info.
Perhaps the addition of the extra bass has just altered my perception of the top end. I’m not sure. Can’t AB the caps obviously.
How about tone? As C4 is decoupled by the resistor can the tone of the C4 cap come through? - I’m assuming not, but I am pretty certain the sound tone is warmer than it was with the original 47uF generic caps.
Can’t seem to quote your post Rayma, but thanks a lot - yes I had thought about putting those big caps horizontally, but I’d probably prefer to try some other caps in that position that are 20 mm high and fit better anyway.
Thanks for your cap recommendation. I’ve used UES MUSE bipolar caps before but have found them a little dull sounding to be honest.
If the cap brand/model does affect the tone a bit in C4 position I would like to try a few different caps and do some fine tuning anyway.
Slightly warm tone aside, I’m very happy with the fuller range sound I’m getting now. Thanks a lot!
If I changed C1 to 22uF (from 10uF) would I gain slightly more bass too? I might try it anyway. Can’t seem to figure out how you work out the bass corner Freq according to C1 cap value into the ZTX384C transistors.
Thanks for your cap recommendation. I’ve used UES MUSE bipolar caps before but have found them a little dull sounding to be honest.
If the cap brand/model does affect the tone a bit in C4 position I would like to try a few different caps and do some fine tuning anyway.
Slightly warm tone aside, I’m very happy with the fuller range sound I’m getting now. Thanks a lot!
If I changed C1 to 22uF (from 10uF) would I gain slightly more bass too? I might try it anyway. Can’t seem to figure out how you work out the bass corner Freq according to C1 cap value into the ZTX384C transistors.
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The C4 is part of the RIAA network, so its value and imperfections will affect the sound.
Just using R2 for the input calculation is close enough, but 33uF is a more appropriate value than the 10uF.
Just using R2 for the input calculation is close enough, but 33uF is a more appropriate value than the 10uF.
Thanks again for the info Rayma. I’ll give some other caps in C4 a go and see how they sound. Seeing what you recommended some UES Muse caps in 25 Volt rating I assume 25V rating is ok? (but the minimum rating possible I assume).
I got 22uF 35 V tantalum’s for C1 as I couldn’t find 33uF ones in 35V rating (as per the stock 10uF 35V caps) but if 25 V rating is ok there too I should be able to find 33uF.
Thanks for the info re R2 and the calculation. Yes that’s around 5 Hz with a 10uF cap, maybe too high for the first stage with all the other high pass filters in the design.
Naim stuff can be bandwidth limited more so than other brands so it was probably international (and the C4 value too). Too much bass loss for me though.
I got 22uF 35 V tantalum’s for C1 as I couldn’t find 33uF ones in 35V rating (as per the stock 10uF 35V caps) but if 25 V rating is ok there too I should be able to find 33uF.
Thanks for the info re R2 and the calculation. Yes that’s around 5 Hz with a 10uF cap, maybe too high for the first stage with all the other high pass filters in the design.
Naim stuff can be bandwidth limited more so than other brands so it was probably international (and the C4 value too). Too much bass loss for me though.
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