Yep Misterdog, it would be great to get a feedback from a current user of Bppbp+ Meldano Muses volume controller.. not sure if anyone has thought of it before though.
I reckon a single Meldano stereo controller would do and channels should be strictly matched. The big questionmark I guess would be whether the circuit might go open or is safe to be used under all circumstances. Any experience with these will be welcome.
I reckon a single Meldano stereo controller would do and channels should be strictly matched. The big questionmark I guess would be whether the circuit might go open or is safe to be used under all circumstances. Any experience with these will be welcome.
Whatever you do ensure that the chosen control cannot go 'open'......
[I had the original board with a well made tth resistors - but on a cheap switch. Yes, it went open and took out a pretty bomb proof Bonsai NX amp and a very expensive speaker driver] Despite this I have to say that as a preamp it is a brilliant design and beats my alternatives hands down in terms of not interfering with the signal.
I know that it is a long thread to plough through but the effort is really worthwhile. Generally I would advise sticking to the original design for ease of mind.
[I had the original board with a well made tth resistors - but on a cheap switch. Yes, it went open and took out a pretty bomb proof Bonsai NX amp and a very expensive speaker driver] Despite this I have to say that as a preamp it is a brilliant design and beats my alternatives hands down in terms of not interfering with the signal.
I know that it is a long thread to plough through but the effort is really worthwhile. Generally I would advise sticking to the original design for ease of mind.
There is so much hype around some of the most expensive pre-amps out there (I'm only ever interested in pre-amps that claim accuracy), it is hard sometimes to keep one's thinking straight and still believe that spending some big moolah on a top end pre-amp will be of benefit.. e.g. I've seen a nice Spectral DMC 30SS for £3k from a dealer in the UK- the hype and reviews around that sound great!
I am still only half way through my BPPBP build due to heavy procrastination ... so am yet to hear mine in action!
I am still only half way through my BPPBP build due to heavy procrastination ... so am yet to hear mine in action!
I sold my Mark Levinson 320s after having compared it to the BPBP running on batteries.
They share exactly the same topology, but the ML uses many Fet switches for the linear volume control where my BPBP uses only 6 relays for a logarithmic control.
The ML also used separate diamond buffers to drive the interlinks to the main amp where the BPBP lacks these unnecessary additional buffers.
Hans
Out of interest, did you find that running it on batteries improved the transparency or even measured better?
Have standardised measurements like THD, crosstalk etc been made of the BPPBP? I do remember seeing noise plots..
Thanks for your replies to my questions folks - I have ADD and find myself drawn to new dopamine hits of thinking about which new bit of gear I could afford or a new project, rather than sitting down to finish my BPPBP build into a Quad FM4 tuner case. I need to connect the enthusiasm for finishing the build with a tangiable gain.
Have standardised measurements like THD, crosstalk etc been made of the BPPBP? I do remember seeing noise plots..
Thanks for your replies to my questions folks - I have ADD and find myself drawn to new dopamine hits of thinking about which new bit of gear I could afford or a new project, rather than sitting down to finish my BPPBP build into a Quad FM4 tuner case. I need to connect the enthusiasm for finishing the build with a tangiable gain.
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Although not looking for a new "hit" like you mention, I've been dragging my butt getting my BPPBP (can we come up with a new name.. please
), and have finally gotten back to it after 6 months. Maybe we can encourage each others continued work by sharing some progress details here as incentive. I'll start:
VolCB board controlled by Arduino Nano based borrowed from DimDim's Lascala.
Hand wired encoder/LED volume display (binary because Im a Computer Geek) with local I2C controller
Still very much a novice arduino programer, spent a LOT of time trying to create a "one knob controls everything(volume, input/output selection)" solution, and decided to give that up for now in favour of separate I2C controlled input and output selectors.
Currently working on adding the code for the above.
I also have a Galaxy case that I want to start doing the front/real panels for (debating here whether I want to give it a go with just my drill press or go whole hog up front and order proper FPE panels).
Attachments
interference from phone
I really like the volume control, it's a very cool project. When I put my phone close to the connectors I can measure that the noise increases (see attachment: the red measurement is with the phone and the black one without; gain is close to 1). The volume control is in a grounded metal housing. I know it's kind of extreme to put the phone next to the connectors, but for the purpose of getting a "perfect" preamp I would really like to get rid of the interference. I already tried to attach some 100p caps from output + and - to the chassis right at the connectors without success. I'd be grateful for any suggestions!
I really like the volume control, it's a very cool project. When I put my phone close to the connectors I can measure that the noise increases (see attachment: the red measurement is with the phone and the black one without; gain is close to 1). The volume control is in a grounded metal housing. I know it's kind of extreme to put the phone next to the connectors, but for the purpose of getting a "perfect" preamp I would really like to get rid of the interference. I already tried to attach some 100p caps from output + and - to the chassis right at the connectors without success. I'd be grateful for any suggestions!
Attachments
Thanks for the reply, Hans. Yes, I'm referring to the XLR input and output connectors.
I'm trying to be as precise as possible, if you need more information don't hesitate to ask.
I'm using one channel of the preamp, the remaining inputs and the second output is not connected. Basically the DA is connected to one input and the output is connected to the AD for measurement. I am using an external power supply, it's a commercial +-19V PSU that I had in the drawer; it works without problems. The metal case that contains the preamp is grounded to mains ground via the case of the external PSU. The circuit's 0V is connected to the case at the XLR connectors (and at no other point).
Besides the noise from the interference the preamp measures very well.
So there is a DA connected ti’s input.
What is this DA doing, is it producing noise or whatever, and what is the sensitivity of the AD ?
In the 0dB position, the preamp is producing ca 12nV/rtHz which means ca 2uV for the 50Khz BW you used.
Is your AD capable of that ?
The other thing is that I see the LF noise rise by 40dB or a factor 100.
I find that very hard to understand.
What do you read when the DA is directly connected to the AD without and with telephone ?
Hans
What is this DA doing, is it producing noise or whatever, and what is the sensitivity of the AD ?
In the 0dB position, the preamp is producing ca 12nV/rtHz which means ca 2uV for the 50Khz BW you used.
Is your AD capable of that ?
The other thing is that I see the LF noise rise by 40dB or a factor 100.
I find that very hard to understand.
What do you read when the DA is directly connected to the AD without and with telephone ?
Hans