I’ve been looking at this as a possible transformer. I’m attracted to it’s nice clean package. Would there be any issues using this?
http://www.talemagroup.com/uploads/documents/product-datasheets/PCB Transformers 1.6-50VA.pdf
http://www.talemagroup.com/uploads/documents/product-datasheets/PCB Transformers 1.6-50VA.pdf
adjusting output level for bi-amping
hi, if anyone could offer some advice. i’m currently planning to use dcb1 with dual output to drive a sony vfet diy and f5turbo monoblock for a pair of speakers both amps have different gain. is there any particular way to calculate and adjust the input level accordingly to make them move in tandem?
regards,
askae
hi, if anyone could offer some advice. i’m currently planning to use dcb1 with dual output to drive a sony vfet diy and f5turbo monoblock for a pair of speakers both amps have different gain. is there any particular way to calculate and adjust the input level accordingly to make them move in tandem?
regards,
askae
You can make one output weaker with a voltage divider (1/4W resistors Lpad) to connect there the more sensitive amp. When you know the amps differences in voltage gain you know the matching ratio of attenuation. Alternatively you can install the Lpad inside the more sensitive amp at its input.
Voltage Divider Calculator
R2 in the link should be chosen no higher than 1/10 the amp's input impedance because R2 is effectively the signal source's output impedance now. Use good quality low noise low ppm resistors. They can be easily installed at the back of each channel's chassis RCA.
Voltage Divider Calculator
R2 in the link should be chosen no higher than 1/10 the amp's input impedance because R2 is effectively the signal source's output impedance now. Use good quality low noise low ppm resistors. They can be easily installed at the back of each channel's chassis RCA.
Hi Salas,
Alternately, can one just add a high value series resistor at the input of the amplifier with the higher gain? For example, if the amp with the higher gain has its R1 of 1kr and R2 of 47kr and if you want to decrease this amps output by 6db , then adding 46kr just before the amps R1 should do it. Any issues with this approach?
Thanks very much.
Nash
P.S: BTW my DCSTB repurposed at 15V works beautifully in my Millett Nutube build.
Alternately, can one just add a high value series resistor at the input of the amplifier with the higher gain? For example, if the amp with the higher gain has its R1 of 1kr and R2 of 47kr and if you want to decrease this amps output by 6db , then adding 46kr just before the amps R1 should do it. Any issues with this approach?
Thanks very much.
Nash
P.S: BTW my DCSTB repurposed at 15V works beautifully in my Millett Nutube build.
Hi Salas,
I'm thinking about "surrounding" my passive volume control with a B1 buffer both in front and behind like Ed Shilling's "Truth" preamp - can I just add the second set of matched jfets to the Mezmerize, or do I need a completely separate supply?
Ir, would it be better to use a 'newer' shunt reg supply altogether?
I'm thinking about "surrounding" my passive volume control with a B1 buffer both in front and behind like Ed Shilling's "Truth" preamp - can I just add the second set of matched jfets to the Mezmerize, or do I need a completely separate supply?
Ir, would it be better to use a 'newer' shunt reg supply altogether?
Hi Nash
This approach can certainly achieve the voltage division you are after but there is a catch. You also create a very high 47k source impedance in that way. Which can bring various negative side effects like higher noise susceptibility, loss of bandwidth, loss of drive. BTW nice to know that the DCSTB PSU worked nicely for you in another application different than its usual partner the DCG3 peamp.
*Another way is make a special cable with the attenuation resistors inside a male RCA. Label its input/output ends and the division ratio. You don't need modify multi purpose equipment in that way. But you just have a special accessory when combining the amps in a biamp system.
You may add the matched JFETs for your extra buffer stage on Mezmerize. It has much spare current and sufficiently low impedance for them also. If there will be some wiring distance add 1R 100uF RC filters very close to their physical rail feed points.
In case of adding an exclusive shunt PSU for that stage I am not sure if the sonic signature will remain as coherent as the DCB1 we know. In case of going with say a UBiB 1.3 for the whole thing it should come out coherent but it will not be the same DCB1 and I don't know how you will like it.
Okay, thanks Salas - extra buffer stage, no problems - RC filter for longer leads, check
Interesting that the Ubib will produce a different signature for simple buffers but I have a spare so I'll try it - curious
I'll be interesting if sandwiching the volume attenuator is beneficial, or not - this is intended to go in front of Nelson's kit Xover from 'the Store' when available
Interesting that the Ubib will produce a different signature for simple buffers but I have a spare so I'll try it - curious
I'll be interesting if sandwiching the volume attenuator is beneficial, or not - this is intended to go in front of Nelson's kit Xover from 'the Store' when available
Depends on the type of pot first of all. Ladder, series, shunt. Then whether the signal source has hi output impedance or not. An extra buffer at the input side makes the whole thing all round compatible and robust for one. OTOH its yet another stage. Try what you like best since you got the parts IMHO.
BTW don't forget about the series input and output resistors in the extra stage. There can be oscillation without them. Due to wide bandwidth. Since there will be no external interconnects between stages you can probably use lower values like 47R or 100R. But do check that the whole new thing is stable in the end, both for pure DC rails and no ringing with square wave signal.
Thanks, will do
I'm using the CloneNote from Uriah Daley at present (variable series impedance set by the ldr) and also playing with the idea of incorporating Dave Slagle's Autoformer for the shunt attenuation so the 'impedance isolation' offered by the B1 buffers will probably be quite significant to the sound - this has been done on "pro-audio' before but unsure if tried in hifi use.
I'm using the CloneNote from Uriah Daley at present (variable series impedance set by the ldr) and also playing with the idea of incorporating Dave Slagle's Autoformer for the shunt attenuation so the 'impedance isolation' offered by the B1 buffers will probably be quite significant to the sound - this has been done on "pro-audio' before but unsure if tried in hifi use.
Similar in pot isolation logic, I had a buffer-pot-gain config in an early 90s preamp of mine. Simply made with opa stages as a Lego, but the buffering was there.
An old diy line preamp
An old diy line preamp
Hi Salas,
I have a Slagle AVC and I have been given to understand that a low impedance buffer installed before it really helps. I was thinking of using the new B1 Mez but the output impedance is around 250r. Can I short the 200r resistor load and then connect the AVC to its outs, thereby the AVC only sees the output impedance of the same sex Jfets which should thus be under 50r?
Thanks.
Nash
I have a Slagle AVC and I have been given to understand that a low impedance buffer installed before it really helps. I was thinking of using the new B1 Mez but the output impedance is around 250r. Can I short the 200r resistor load and then connect the AVC to its outs, thereby the AVC only sees the output impedance of the same sex Jfets which should thus be under 50r?
Thanks.
Nash
I'm very interested in this matter (building an AVC myself). Are R2 and R8 in the schematic these 200r Resistors you are talking about ?
thank you!
I could use a little help. I have all I need to build this but can't find the BC560CTA for the regulator anywhere. It's obsolete. I did find a BC557 ATA instead but just realized it's Hfe range is much lowere than a 'C' part. And higher noise reated :-( I can't find a cross for this or a reference to the probelm in ths thread. Please help with a recommendation if you can. Or does anyone have one they would sell? Many thanks.