I have this preamp and a Denon DL 110 high output MC cartridge. But the sound playing records is much quieter than with other sources. The preamp is designed to take a 5mV input from a MM cartridge, but the Denon only produces about 1.6mV. Is there a simple way I can up the gain of the EF86 stage to better suit the cartridge, or do I need a little head amp to get me from 1.6 to 5mV?
I think I'm just going to stick this in between the turntable and the preamp.
http://rssconsultancy.co.uk/article64b.pdf
http://rssconsultancy.co.uk/article64b.pdf
You need additional voltage gain between the cartridge and the EF86.
A solution to this sort of problem is having a low noise, high transconductance, JFET source follower ideally load the cartridge and have the FET drive a step up microphone transformer. Something like this CineMag transformer seems right for this situation. Sowter (UK) is much closer to you than California. Unfortunately, my perusal of the Sowter web site did not turn up a similar product. Perhaps, you will have better luck in spotting a suitable Sowter product.
A solution to this sort of problem is having a low noise, high transconductance, JFET source follower ideally load the cartridge and have the FET drive a step up microphone transformer. Something like this CineMag transformer seems right for this situation. Sowter (UK) is much closer to you than California. Unfortunately, my perusal of the Sowter web site did not turn up a similar product. Perhaps, you will have better luck in spotting a suitable Sowter product.
A transformer could better adopt the levels, thers is transformers for MC
pickups from several makers, lundahl is one.
No, no, a thousand times no! A common emitter BJT gain stage might be quiet enough, but its linearity is definitely suspect.
Put a C5 cap parallel to R9 will give you more gain. R10 is useless and should be cleared.
To have more gain in the phono section itself, the working point of the EF86 should be changed to higher amplification. That includes the change of some resistors.
Best way is to use a special MC transformer in front of the circuit. But good transformers are expensive.
So try method one first, if not sufficient, try method two and change the setting of the EF86 for higher gain.
To have more gain in the phono section itself, the working point of the EF86 should be changed to higher amplification. That includes the change of some resistors.
Best way is to use a special MC transformer in front of the circuit. But good transformers are expensive.
So try method one first, if not sufficient, try method two and change the setting of the EF86 for higher gain.
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Either reduce R3 or build a voltage divider to attenuate the line signals from the other sources.
Transformer suggestions are wrong, because DL110 is intended for 47kΩ or more.
EF 86 gain can not be increased much more due to limitations of the tube.
This stage must be very noisy due to large R3.
No, R3 is not part of the RIAA correction, but frequency response will be even worse
with increased gain of this stage.
This seems to be an Elektor schematic, reminds me to Quad tube preamp (compare),
you would want to keep the Elektor pcb if you have it I guess.
EF 86 gain can not be increased much more due to limitations of the tube.
This stage must be very noisy due to large R3.
No, R3 is not part of the RIAA correction, but frequency response will be even worse
with increased gain of this stage.
This seems to be an Elektor schematic, reminds me to Quad tube preamp (compare),
you would want to keep the Elektor pcb if you have it I guess.
I have used the common-bas circuit described here for a couple of years: Moving Coil Cartridge Head Amps
It sounds really good! To my ears better than my Lundahl LL1941 transformers.
It sounds really good! To my ears better than my Lundahl LL1941 transformers.
Regardless of how they are configured, the linearity of BJT gain stages is highly suspect.
Denon DL110 High-Output Moving Coil System
Ausgangsspannung/Ausgangsimpedanz: 1,6 mV / 160 Ohm
The system has 160 Ohm output impedance and thats not unusual in the world of MC cartridges. There are plenty of MC step up transformers available.
I think, with a different setting of resistor values the gain could be increased for the phono section. The tube runs at 1.4mA and 100K anode resistor. With a 220K it gives plenty of gain. Look at the Philips datasheet, this isn't the high level of gain an EF86 is capable of. Even with a 100K anode resistor it could be run at 2.1mA which will give more gain.
Ausgangsspannung/Ausgangsimpedanz: 1,6 mV / 160 Ohm
The system has 160 Ohm output impedance and thats not unusual in the world of MC cartridges. There are plenty of MC step up transformers available.
I think, with a different setting of resistor values the gain could be increased for the phono section. The tube runs at 1.4mA and 100K anode resistor. With a 220K it gives plenty of gain. Look at the Philips datasheet, this isn't the high level of gain an EF86 is capable of. Even with a 100K anode resistor it could be run at 2.1mA which will give more gain.
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Commonplace MC cartridge step up transformers have 1:10 or even higher ratios. 20 dB. of voltage gain will (likely) overload the tubed circuitry. Those 1:10 SUTs are routinely paired with 500 μV. O/P cartridges.
IMO, the Denon DL110 is neither LOMC nor HOMC. 🙁
OK, then tweaking this circuit for higher gain.
Change R2 to 330K and R4 to 1K makes the tube run at approx. 2.1mA. Much higher gain.
But I would do this combined with method one.
Change R2 to 330K and R4 to 1K makes the tube run at approx. 2.1mA. Much higher gain.
But I would do this combined with method one.
What is that preamp, and why only a single stage RIAA? Such designs could be found in the old high end European Radiograms with high output magnetic cartridges in a PE REX changer. The other place I saw this used was in Seeburg Jukeboxes. You're already asking an awful lot from that tube, so I would agree that the better approach would be to attenuate the other sources. Either that, or find/make a head amp. Just make sure you don't overload the EF86.
It is the Elektor schematic, yes. I've already built it, so I'd like two give it a run out. I just need to better match the preamp's input impedance and boost the signal three or four times. Hence my idea of using the BC214L circuit.
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- Everybody is free to have a look at the original DL-110 data to confirm 47kΩ ..
- Quad 22 phono is here : http://www.keith-snook.info/amplifier-hifi-schematics/QUAD 22 RIAA PCB.pdf
- Quad 22 phono is here : http://www.keith-snook.info/amplifier-hifi-schematics/QUAD 22 RIAA PCB.pdf
I would have thought PRR would have posted on this as he did in 2010 in EL34 world -
max power of EF86
Scroll down for his post.
max power of EF86
Scroll down for his post.