Im building this preamp. I completed all psu part and there is only main circuit left. I have a question about resitor power rating.
Could i use cmf55 1k for the grid resistor and cmf60 for the 120r which make 6v6 work like triode?
Could i use cmf55 1k for the grid resistor and cmf60 for the 120r which make 6v6 work like triode?
I wonder what the filter maximum capacitance is based on? Is that a figure from the tube datasheet? Is it a limit imposed by inrush current, or ??
Its a figure from the datasheet and its about a safe limit to peak current stress factor for proper reliability and no start up arcing
My ugly 6V6 build
I finally finished building the high gain version of the 6V6 pre-amp. I built it with an SSHV2 for each channel and vibration dampers underneath the choke & power transformer. The 6v6 tubes are on their own platform decoupled from the rest of the pre-amp. I still have to put a skirt around the frame but I'm having too much fun listening.
I have to say it sounds very very good. It is driving a Baby Huey PP EL-84 amp.
This is only my second build from scratch. I had a few issues with hum and grounding schemes but I was able to get them resolved (DHT-ROB has a nice web-page with grounding hints). My sincere thanks to Salas and Tea-Bag for the circuits and kits. Fantastic stuff gentlemen.
I finally finished building the high gain version of the 6V6 pre-amp. I built it with an SSHV2 for each channel and vibration dampers underneath the choke & power transformer. The 6v6 tubes are on their own platform decoupled from the rest of the pre-amp. I still have to put a skirt around the frame but I'm having too much fun listening.
I have to say it sounds very very good. It is driving a Baby Huey PP EL-84 amp.
This is only my second build from scratch. I had a few issues with hum and grounding schemes but I was able to get them resolved (DHT-ROB has a nice web-page with grounding hints). My sincere thanks to Salas and Tea-Bag for the circuits and kits. Fantastic stuff gentlemen.
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Hello,
Thinking about this wonderful Salas 6V6, which will extend to 10 years soon. Before I start this project I would like to know what version would work best for me:
-Gain 15dB
-Gain 7dB
-Buffer (no gain).
I use digital source via DAC only. Should I use:
-Balanced out (and adapter to RCA), or
-SE RCA?
The problem I foresee is that 6V6 has to drive low impedance inputs of the power amp and twin active subs – each has 10k input.
I would like to avoid active crossover.
Appreciate help!
Thinking about this wonderful Salas 6V6, which will extend to 10 years soon. Before I start this project I would like to know what version would work best for me:
-Gain 15dB
-Gain 7dB
-Buffer (no gain).
I use digital source via DAC only. Should I use:
-Balanced out (and adapter to RCA), or
-SE RCA?
The problem I foresee is that 6V6 has to drive low impedance inputs of the power amp and twin active subs – each has 10k input.
I would like to avoid active crossover.
Appreciate help!
Attachments
Best use would be with cathode follower mode to no less than 15k combined load and no less than 28dB gain in the power amps. Native SE connection or adapter are equivalent. When you need really low impedance drive with much current reserve I would recommend taking a look to DCG3 also while keeping in mind its SS and won't go to less than 6dB gain setting.
P.S. Maybe you can up the input load resistors in your amps if they will not be creating any significant side-effects
P.S. Maybe you can up the input load resistors in your amps if they will not be creating any significant side-effects
Thanks Salas,
Apparently, I could not maintain minimum 15k combined load. The gain, I think is no problem, the power amp has min 100W, and subs 400W each.
I am not sure I understand how to insert load resistors and increase input Z.
Would it be helpfull to insert TVC in the input of the 6V6, would it lower the Z-out?
Alternatively, I would look into DCG3, maybe it would be more appropriate for me.
P.S. I thought, the buffer version 6V6 would be better for me, with less Z-out.
brgds,
Predrag
Apparently, I could not maintain minimum 15k combined load. The gain, I think is no problem, the power amp has min 100W, and subs 400W each.
I am not sure I understand how to insert load resistors and increase input Z.
Would it be helpfull to insert TVC in the input of the 6V6, would it lower the Z-out?
Alternatively, I would look into DCG3, maybe it would be more appropriate for me.
P.S. I thought, the buffer version 6V6 would be better for me, with less Z-out.
brgds,
Predrag
There is an input to ground resistor that sets the amp's input Z in most cases. Sometimes its arbitrary and can be changed, sometimes there is a reason its low value like its a BJT DC coupled input and the base current can create DC offset on a large value input Z.
No a TVC on input can't do that, an output transformer can.
The capacitor coupled buffer 6V6 has something like 1.5K Z out If I remember well.
No a TVC on input can't do that, an output transformer can.
The capacitor coupled buffer 6V6 has something like 1.5K Z out If I remember well.
Hi,
That problem arises when trying to to drive the Z in + IC capacitance with the unbuffered output of a valved preamp.
IOW, if you don't need the gain go with a buffered output that can drive the SS device or add a CF to the output of the preamp which INHO is invariably the better solution.
Cheers, 😉
That problem arises when trying to to drive the Z in + IC capacitance with the unbuffered output of a valved preamp.
IOW, if you don't need the gain go with a buffered output that can drive the SS device or add a CF to the output of the preamp which INHO is invariably the better solution.
Cheers, 😉
Thanks,
Sorry, I do not understand ...to add a CF to the output of the preamp..?
Do you mean CF version of the 6V6?
Appologise for my lack of knowledge.
Attachments
Hi,
CF = Cathode follower, a buffer stage that lowers Zout and when designed properly can deliver enough current to drive lowish Zin and interconnect capacitance.
Best, 😉
CF = Cathode follower, a buffer stage that lowers Zout and when designed properly can deliver enough current to drive lowish Zin and interconnect capacitance.
Best, 😉
I don't see any determining Zin resistor to alter it's value in that schematic portion. Maybe it's a symmetric amp and there is some network doing that.
Given the 3.3K combined load and capacitance of three interconnects also to drive in parallel better do SS IMHO. Or some parallel cathode follower of many tubes. That may bring matching tubes issues though.
Hello Frank
6V6 CF isn't enough for what he needs I am afraid. It's about 1.5K output impedance. And the load will be two active subs and a main cabs amp of 10K Zin each. Plus long ICs.
Thank you guys!
I have just checked, the pre-out for both subs goes first to Behringer FBQ2496 which has 15k input, and 200r out.
Subs have also high level inputs (100k), for connecting to amp speaker terminal, but then I loose convenience to fix bass response via FBD in my room. I suppose the signal from the 6V6 will be too weak for this input.
Anyway, if I have integrated amp with pre-out for subs, would it be helpfull to use 6V6 CF as a buffer or is it overkill?
I have just checked, the pre-out for both subs goes first to Behringer FBQ2496 which has 15k input, and 200r out.
Subs have also high level inputs (100k), for connecting to amp speaker terminal, but then I loose convenience to fix bass response via FBD in my room. I suppose the signal from the 6V6 will be too weak for this input.
Anyway, if I have integrated amp with pre-out for subs, would it be helpfull to use 6V6 CF as a buffer or is it overkill?