I think it made a reputation in tube circuits where it can interface better, used as an inductive load or coupled through interstage Tx keeping the filter impedance low VS what the tubes would really want to see while avoiding C coupling etc.
Otherwise it makes for a biggish loop area where the signal can be tiny.
Having used the Zanden & Wavac LCR tube phonos for enough times I did not get impressed.
Otherwise it makes for a biggish loop area where the signal can be tiny.
Having used the Zanden & Wavac LCR tube phonos for enough times I did not get impressed.
Hi, sorry for just butting in on the thread. The thread is colossal now and if the information is in here I can't find it.
I think I have enough spare parts to build a valve pre amp. I have some 6n1p 's and some 6n6p 's.
Is a cathode follower a good circuit to use here. ? And what valve?
Or could I do a similar thing with the 2sk170bl's, I also have a double burson op amp.
forgot to add my transformer will give 180 volts Dc
Thanks Alan
I think I have enough spare parts to build a valve pre amp. I have some 6n1p 's and some 6n6p 's.
Is a cathode follower a good circuit to use here. ? And what valve?
Or could I do a similar thing with the 2sk170bl's, I also have a double burson op amp.
forgot to add my transformer will give 180 volts Dc
Thanks Alan
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We don't talk valves in this thread. You would not find anything relevant even if reading it through.
Transfering it to valves it will not be analogous for noise and It will still take a PNP semiconductor to make a hybrid shunt cascode on input.
You may want to have a look at the Valve Itch μ follower phono with 6N2PEV & 6SN7 instead. Its thread link and an example build.
Transfering it to valves it will not be analogous for noise and It will still take a PNP semiconductor to make a hybrid shunt cascode on input.
You may want to have a look at the Valve Itch μ follower phono with 6N2PEV & 6SN7 instead. Its thread link and an example build.
I have a question related to the parts choice for RIAA.
What capacitors type would you use in RIAA: MKP or Russian PIO?
I have two chose between two in paralell Russian PIO 0.033uF and 0.001uF = 0.034uF
Or Vishay-RODERSTEIN MKP-1837 two in series 0.068uF = 0.034uF
0.034uF is my target...
Please let me know your opinion.
Thank you.
What capacitors type would you use in RIAA: MKP or Russian PIO?
I have two chose between two in paralell Russian PIO 0.033uF and 0.001uF = 0.034uF
Or Vishay-RODERSTEIN MKP-1837 two in series 0.068uF = 0.034uF
0.034uF is my target...
Please let me know your opinion.
Thank you.
Salas
I did not mean as a "PHONO" stage I meant as a "pre amp" after your phono stage. I don't like interconnects and like to build integrated all in one systems. Its cheaper when you think of the price of just one set of decent leads and plugs and sockets. I am thinking of valve pre , simply because I have all the bits sat here doing nothing. But I don't know whether to use cathode follower, beta follower etc????
I did not mean as a "PHONO" stage I meant as a "pre amp" after your phono stage. I don't like interconnects and like to build integrated all in one systems. Its cheaper when you think of the price of just one set of decent leads and plugs and sockets. I am thinking of valve pre , simply because I have all the bits sat here doing nothing. But I don't know whether to use cathode follower, beta follower etc????
MKP. The 1837s are better MKP type being film and foil. PIO has much loss for use in filtering.
Housing HV and heaters power lines along with the phono with no hum and buzz is one prerequisite. With experience it can be achieved.
Another problem is that the JFETs readily respond to temperature changing their IDSS. Especially the input ones. Neighboring hot valves is looking for trouble. TO-92 mini sinks for the JFETs and a mesh top for ventilation could help a lot but its still taking chances.
Considering the line preamplifier valve circuit itself, a common cathode-cathode follower cascade of noval valves attains reasonable quality at say Conrad Johnson PV10 level (a characteristic unit of such topology).
Thank you a lot.
And for signal path?
Mundorf "Supreme" or "Surpeme Silver - Oil", or new "EVO – Silver/Gold - Oil?
Thank you.
I don't think 1837s are film and foil. They are metallized film. I have been trying to find some Wima FKPs for this because they are film and foil.
That said, the Vishays are very good and have a great reputation.
I am not familiar with the sound of your BHL phono and your system so to imagine or recommend possible tonal synergies. SIO is favored by many and you can't go much wrong with it I guess.
You are right they are not. I must have mixed some other type# in my memory.
They perform fine nonetheless and most importantly for RIAA they are available in 1% too, saving money on buying a batch for selection plus needing an $500 LCR meter.
Yes, finding <5% caps these days is difficult. Panasonic used to make some nice polyproylenes at 2% tolerance, but they were discontinued. I think the Wima FKPs tend to group better than their spec, but you are right, without a really good cap meter it is shooting blind. I'll probably use the 1837s and add polystyrene like you suggest in the build guide.
what seems a bit too much
In most samples Vgs(OFF) will be consistent enough for same or near IDSS.
It holds information for the gain a sample can achieve. Its good to know and try match when the degeneration will be low (small Rs value).
gm = |2*IDSS/Vp * [ 1 - (Vgs/Vp) ]|
When Vgs=0 then gm0=|2*IDSS/Vp|
Voltage gain in common source is -(gmRD/1+gmRs)
From the equations you can see why try matching depends on the degeneration level to be applied in the position the JFET is meant for. The more Rs the less it matters.
The samples variation for Vp at same IDSS will be unworthy investigating especially in loop feedback circuits where the gain is set by the external Fb network.
Vp is another way to say Vgs(OFF). Comes from the term "pinch off voltage".
It holds information for the gain a sample can achieve. Its good to know and try match when the degeneration will be low (small Rs value).
gm = |2*IDSS/Vp * [ 1 - (Vgs/Vp) ]|
When Vgs=0 then gm0=|2*IDSS/Vp|
Voltage gain in common source is -(gmRD/1+gmRs)
From the equations you can see why try matching depends on the degeneration level to be applied in the position the JFET is meant for. The more Rs the less it matters.
The samples variation for Vp at same IDSS will be unworthy investigating especially in loop feedback circuits where the gain is set by the external Fb network.
Vp is another way to say Vgs(OFF). Comes from the term "pinch off voltage".