VR SHUNT REG
In my experience so far, I really like CCS + tube shunt (0C3 being the best),
I am using a headphone amp right now whit this arrangement and its dead quiet. I am always using very low capacitors to bypass the tube shunts...so on the order of 0.01-0,05uF. For 26 I will use only passive elements...a CLCLC configuration but the chokes needs to have around 30-50H. The psu output impedance is not so important for 26 tube...
In my experience so far, I really like CCS + tube shunt (0C3 being the best),
I am using a headphone amp right now whit this arrangement and its dead quiet. I am always using very low capacitors to bypass the tube shunts...so on the order of 0.01-0,05uF. For 26 I will use only passive elements...a CLCLC configuration but the chokes needs to have around 30-50H. The psu output impedance is not so important for 26 tube...
Hi!
Congrats for the beautiful build Felipe!
I agree! While you are at it you might want to try a pure choke input filter. I am using LCLCLC for preamps with the last LC separate for each channel
Best regards
Thomas
Congrats for the beautiful build Felipe!
I agree! While you are at it you might want to try a pure choke input filter. I am using LCLCLC for preamps with the last LC separate for each channel
Best regards
Thomas
Kevin, did you have a CCS upstream from the VR tube, or a resistor? The CCS made a huge difference for me.
Nice looking build Merlin..
About 12yrs ago I initially tried the VR150/0D3 in my early 26 based line stage design, but found the noise from the gas tube to be excessive in my application.. The plate to line transformers in question were UTC HA-133: 5:1 15K:600 which I am still using. The power amps had modest gain of about 10dB but were driving a rather efficient JBL speaker system (>100dB) wondering now whether I just had a batch of particularly noisy gas tubes.. (NOS) My opinion at the time was that it was almost quiet enough and had the speakers been about 6dB less efficient all would have been well.
My current speaker system is also over the 100dB mark so all of my electronics have to be extremely quiet.
Thanks Kevin, today I experimented with mobile phone at less than 1 cm of the 26 = no noise, is incredible I was afraid of microphony and noise because all people in the thread told like a characteristic of 26. Can be your VR150/OD3 aren't good or I'm using other power transformer+choke (Bartolucci) also can be the OPT I'm use Lundhals LL1660, do you use Rod Coleman heater regulators?
You are right my speaker system have 94dB and also all my eletronics have to be quiet.
Greetings
Felipe
Attachments
Do you refer to those red marked? if yes are the filament resistors.
Sorry, didn't explained well.
I mean IC (interconnects), these withe.
Thanks.
These white are 4 x 24AWG all teflon copper silver plated, screen is also copper silver plated, inside and outside dielectric is always PTFE
Looks nice, do you strand the 4 wires?
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Is it the shunt mod you are thinking of?
Shunt Pot Volume Control for Better Sound and/or Gain Reduction - World-Designs-Forum
Shunt Pot Volume Control for Better Sound and/or Gain Reduction - World-Designs-Forum
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
It is the same cable that Erno Borbely uses in his house.
Thanks Filipe.
En hora buena por tu implementación del preamp.
Now I'm trying like attached pic, not exactly shunt but sounds very good, I use two 18k Shinkoh resistor and the improvement is big.
What do you think about the resistor value for shunt type also 18-20K?
TIA
Felipe
Attachments
An externally hosted image should be here but it was not working when we last tested it.
My 26 Preamp. Thanks for this thread and the helpful guys keeping this thread as educational as can be.
Abe
Hello guys,
Just want to add info about the umbilical cord. It is about 5 feet using 300V/16Ga twisted and encased with braided shield for the B+ and 0V, 200V/18Ga twisted and individually shielded (per pair) for the two filament raw DC wires. 16 Ga Copper shielded for IEC and 18Ga shielded for chassis connections. All wires were then enclosed in black nylon jacket with all shields tied together.
Connectors are Neutrik NLT8MP (chassis) and NL8MPR(cord ends) with pins +/- 1 for heater 1, +/- 2 for Chassis GND and IEC GND, +/- 3 for B+ and 0V, and finally +/- 4 for Heater 2.
Enjoying the preamp as I type.
Abe