Really, Tom? I have bought from them many times, including very small orders. Is this just since the pandemic, perhaps?
The mail from RS components, attached, states:
Your order at RS Components
Dear Mr. Pot,
We thank you for you interest in RS Components.
Unfortunately we cannot process your request.
RS Components is a supplier of electronics and maintenance products and sells to companies and professional customers only. To process your order a Chamber of Commerce number is needed.
We cannot serve private persons for this reason.
jada, jada, jada
Your order at RS Components
Dear Mr. Pot,
We thank you for you interest in RS Components.
Unfortunately we cannot process your request.
RS Components is a supplier of electronics and maintenance products and sells to companies and professional customers only. To process your order a Chamber of Commerce number is needed.
We cannot serve private persons for this reason.
jada, jada, jada
Attachments
I'm sorry to read that. They much improved their service within the UK several years ago, including free delivery for small orders. I'm guessing this was due to competition from Mouser (fantastic service) and Digikey. I only buy from RS, indeed, when I have a small order.
Here is the load box I'm building to test the amp (and my guitar amps). I plan to use a Behringer audio interface as a ADC.
Here is a teaser of what it's gonna look like.
In front are the LEDs that light up in case the signal is too large and the attenuation knob. In the right is the output to external speakers.
Note the 'ventilation holes'. They were meant for the switches to switch between resistive load and passing to an actual speaker. Unfortunately I didn't take the threaded 'pillars' in the corners used to mount the bottom plate into account...
The back has the outputs to the ADC and some BNC connectors to easily attach a hardware scope to it. The _left_ has the banana jack inputs for the hifi amp I'm building and the 6.3mm jack(s) for a guitar amp.
Here is a teaser of what it's gonna look like.
In front are the LEDs that light up in case the signal is too large and the attenuation knob. In the right is the output to external speakers.
Note the 'ventilation holes'. They were meant for the switches to switch between resistive load and passing to an actual speaker. Unfortunately I didn't take the threaded 'pillars' in the corners used to mount the bottom plate into account...
The back has the outputs to the ADC and some BNC connectors to easily attach a hardware scope to it. The _left_ has the banana jack inputs for the hifi amp I'm building and the 6.3mm jack(s) for a guitar amp.
Today a new set of parts arrived. Despite the excessive planning, the plan didn't survive contact with reality. Here are some shots of the dry fitting. Nearly all electrical stuff has to be done.
Hi guys,
I finally managed to solder the power supply and 1 channel. It was quite some work and I made it too difficult for myself doing the PS p2p in a very tight space. Also the enamel coating on the transformer wire was a nasty surprise for me. The tinned wires of the Hammond transformers I'm used to are much easier to work with.
The startup, however, was quite easy so far. I have plenty of HT, the preamp seems to be working nicely (first indications...) and even the PP stage produces a nice sine wave. However, I am under the impression that the bias for the 6V6's are not OK. I use the Baby Huey current source. The 0.6V voltage drop over (part of) the transistor and the 18R resistor should result in a current of 30mA. 18R resistor actually measures 18.2R, voltage drop is 0.6V. But I think the current limiter, 100W lightbulb, is burning too bright. Also if I measure the cathode voltages the measure 7V and 14V; something must be off.
Any ideas how I should tackle this one?
I finally managed to solder the power supply and 1 channel. It was quite some work and I made it too difficult for myself doing the PS p2p in a very tight space. Also the enamel coating on the transformer wire was a nasty surprise for me. The tinned wires of the Hammond transformers I'm used to are much easier to work with.
The startup, however, was quite easy so far. I have plenty of HT, the preamp seems to be working nicely (first indications...) and even the PP stage produces a nice sine wave. However, I am under the impression that the bias for the 6V6's are not OK. I use the Baby Huey current source. The 0.6V voltage drop over (part of) the transistor and the 18R resistor should result in a current of 30mA. 18R resistor actually measures 18.2R, voltage drop is 0.6V. But I think the current limiter, 100W lightbulb, is burning too bright. Also if I measure the cathode voltages the measure 7V and 14V; something must be off.
Any ideas how I should tackle this one?
Attachments
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I guess it was the current limiter limiting the HT voltage. Once I removed the limiter, after taking a brave pil, the bias went up (down) to -24V for both; I guess that's OK. Of course I fell victum to the 50/50/90 rule: a horrendous squeel! I removed the feedback and I was able to play some (mono) music.
Here are some scope screenshots of a 1kHz and 10kHz signal. Top is output, bottom is input. I'm using a Behringer U-PHORIA UMC204HD (192kHz) as a signal source at max output without clipping. There is quite some ringing, but it is already present on the input...
I still have to investigate some things. And as this is quite new to me, I'm constantly thinking whether what I see is normal.
I have some 'floating' on the input. The power supply voltage has some ~5Hz, ~100mV(?) flutter. But the output seems quite solid.
Besides that I have some ~200kHz source somewhere. First I thought is was the amp, but my DAC and even my phone shows it. Maybe it's the scope? And at low signals tapping anything near the amp is visible on the scope as some additional oscillation. No single component nor tube in particular seems to be the culprit.
Further measurement will follow, but I will have to continue building my load box and understand my ADC/DAC better and will have to learn the audio analyzer software. And maybe I need a analog signal generator to supply a nice square wave to begin with.
What about the scope images? Any good?
Any advice how to continue?
Anything?
I still have to investigate some things. And as this is quite new to me, I'm constantly thinking whether what I see is normal.
I have some 'floating' on the input. The power supply voltage has some ~5Hz, ~100mV(?) flutter. But the output seems quite solid.
Besides that I have some ~200kHz source somewhere. First I thought is was the amp, but my DAC and even my phone shows it. Maybe it's the scope? And at low signals tapping anything near the amp is visible on the scope as some additional oscillation. No single component nor tube in particular seems to be the culprit.
Further measurement will follow, but I will have to continue building my load box and understand my ADC/DAC better and will have to learn the audio analyzer software. And maybe I need a analog signal generator to supply a nice square wave to begin with.
What about the scope images? Any good?
Any advice how to continue?
Anything?
Attachments
Ringing must by definition happen *after* the stimulus. Only digital artifacts can happen *before* the stimulus.
YOS,
Chris
YOS,
Chris
I might have misused the term ringing. It depends on the sample rate of the dac. That matches with your statement.
Any other comment? I need some guidance without having explicit questions...
Any other comment? I need some guidance without having explicit questions...
Your use of "ringing" is the conventional one, and completely correct.
Your scope photo shows the ringing happening *before* the stimulus - time on a scope passes from left to right. Amplifiers cannot do this; it would reverse causality. So, what you're seeing is made in a digital filter.
YOS,
Chris
Your scope photo shows the ringing happening *before* the stimulus - time on a scope passes from left to right. Amplifiers cannot do this; it would reverse causality. So, what you're seeing is made in a digital filter.
YOS,
Chris
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