planet10 said:
I have analyzed the wav files they are using for demonstration. The reason why they sound horrible is that the signals are corrupted at low level (parts of the signals are simply missing). This has not much to do with THD/IMD and IMHO this kind of demonstration is missleading.
On the other hand, I agree that THD and IMD as a simple number does not say much, that's why I am speaking about the necessity of spectral analysis.
Amplifier Signal to Noise
Hi Everyone,
This weekend has been busy for me so only just back at my computer. Will reply to questions asap.
I have set up and measured the noise figures for the amplifier with the STW34NB20 PowerMESH mosfets.
Measured across the 8 ohm load. Test setup on bench. No special grounding or other tweeks so some of the noise may still be pickup in the leads etc. as it is very difficult to measure down at these levels.
Measurment bandwidth is 10 Hz to 100 kHz.
Full power is 20 Volts ac RMS - 50 watts - just into clipping.
Noise is 13 uV (micro-volts).
Best wishes,
Susan.
P.S.
Have to make supper now.
Hi Everyone,
This weekend has been busy for me so only just back at my computer. Will reply to questions asap.
I have set up and measured the noise figures for the amplifier with the STW34NB20 PowerMESH mosfets.
Measured across the 8 ohm load. Test setup on bench. No special grounding or other tweeks so some of the noise may still be pickup in the leads etc. as it is very difficult to measure down at these levels.
Measurment bandwidth is 10 Hz to 100 kHz.
Full power is 20 Volts ac RMS - 50 watts - just into clipping.
Noise is 13 uV (micro-volts).
Best wishes,
Susan.
P.S.
Have to make supper now.
Re: inputtransformer.
Hi hostmaster ,
From the results I have from the 30VA and 15VA toroids.
http://www.susan-parker.co.uk/zeus-toroid-amp-1.htm
Input Transformer - 15VA
Bandwidth: 10Hz to 25.5 kHz (-3 dB), 31.5 kHz (-6dB)
With modern winding and construction techniques I am hazarding that the transformers will be similar enough to give those sort of figures.
At the end of the day one has to try one out. These are made for 50/60 Hz mains and the wideband performance is much better that I would have thought.
At least the cost is small relative to custom transformers.
Best wishes,
Susan.
Hi hostmaster ,
hostmaster said:
From the results I have from the 30VA and 15VA toroids.
http://www.susan-parker.co.uk/zeus-toroid-amp-1.htm
Input Transformer - 15VA
Bandwidth: 10Hz to 25.5 kHz (-3 dB), 31.5 kHz (-6dB)
With modern winding and construction techniques I am hazarding that the transformers will be similar enough to give those sort of figures.
At the end of the day one has to try one out. These are made for 50/60 Hz mains and the wideband performance is much better that I would have thought.
At least the cost is small relative to custom transformers.
Best wishes,
Susan.
Re: Reading trough a fine thread,
Hi extremy,
If you are making a full transformer rather than a center tapped inductor then the best way is to wind all the wires together.
With 1.0 mm wire you could just use three windings although four would be preferable.
If you can wind all the turns in one go then that is best.
Separating the windings into layers - whilst functional - decreases the coupling and reduces the bandwidth. However this may still be more than adequate.
I haven't tried winding one (yet) so I can't judge the performance.
A line driver unit using a DRV134 and AD815 per channel from your AV unit line outputs should be fine to drive the amplifier input transformer. Crossovers can be done here too.
Have to use the decoded outputs as Dolby won't license their decoder unless one has a big factory churning out boom boxes.
Thank you.
Best wishes,
Susan.
Hi extremy,
extremy said:
If you are making a full transformer rather than a center tapped inductor then the best way is to wind all the wires together.
With 1.0 mm wire you could just use three windings although four would be preferable.
If you can wind all the turns in one go then that is best.
Separating the windings into layers - whilst functional - decreases the coupling and reduces the bandwidth. However this may still be more than adequate.
I haven't tried winding one (yet) so I can't judge the performance.
A line driver unit using a DRV134 and AD815 per channel from your AV unit line outputs should be fine to drive the amplifier input transformer. Crossovers can be done here too.
Have to use the decoded outputs as Dolby won't license their decoder unless one has a big factory churning out boom boxes.
Thank you.
Best wishes,
Susan.
FFT - 2SK1529 lateral FETS
Dear All,
Some "real" test results now at:
http://www.susan-parker.co.uk/zeus-test-2sk1529-fft-1khz.htm
Best wishes,
Susan.
Dear All,
Some "real" test results now at:
http://www.susan-parker.co.uk/zeus-test-2sk1529-fft-1khz.htm
Best wishes,
Susan.
Sowter made OP transformer bobbins
Dear All,
From Sowter:
=============
The price for the would bobbin only is UKP 72.25 each.
Complete transformer is UKP 128.95 each.
We will assign the type number 9840. Anyone can use this to order.
S/T/O suffixes as normal for the Fully Shrouded / Drop Through / Open Frame options with dimensions and weights for the N type.
SOWTER AUDIO TRANSFORMERS (E A Sowter Ltd)
Web site: http://www.sowter.co.uk
SALES: sales@sowter.co.uk
SUPPORT: support@sowter.co.uk
=============
Best wishes,
Susan.
Dear All,
From Sowter:
=============
The price for the would bobbin only is UKP 72.25 each.
Complete transformer is UKP 128.95 each.
We will assign the type number 9840. Anyone can use this to order.
S/T/O suffixes as normal for the Fully Shrouded / Drop Through / Open Frame options with dimensions and weights for the N type.
SOWTER AUDIO TRANSFORMERS (E A Sowter Ltd)
Web site: http://www.sowter.co.uk
SALES: sales@sowter.co.uk
SUPPORT: support@sowter.co.uk
=============
Best wishes,
Susan.
Re: STW34NB20
Hi Darkmoebius,
There is a diference, but it is quite subtle.
The bass seems tighter with the bigger transformer and lower output impedance, but that could also be due in part to the TI headphone amp drive to the input transformer.
I need to make up a pair of amps that I can A/B test against my original monoblocks.
BTW there are now FFT tests on my original amp at:
http://www.susan-parker.co.uk/zeus-original-irfp150-pics-fft-1khz.htm
Which has pics of how it is built, plus a HP 8903B distortion v power level for both 2:1 and 4:1 output transformer configurations, plus 1 watt and 2 watt FFTs.
I have used the HP generator as I have to be very careful about not blowing up the soundcard input and I am still sorting out my methodologies to ensure that I don't.
I am confident that the results will improve with the FFT software's internal generator (the stuff above 8 khz in particular).
Best wishes,
Susan.
Hi Darkmoebius,
darkmoebius said:
There is a diference, but it is quite subtle.
The bass seems tighter with the bigger transformer and lower output impedance, but that could also be due in part to the TI headphone amp drive to the input transformer.
I need to make up a pair of amps that I can A/B test against my original monoblocks.
BTW there are now FFT tests on my original amp at:
http://www.susan-parker.co.uk/zeus-original-irfp150-pics-fft-1khz.htm
Which has pics of how it is built, plus a HP 8903B distortion v power level for both 2:1 and 4:1 output transformer configurations, plus 1 watt and 2 watt FFTs.
An externally hosted image should be here but it was not working when we last tested it.
I have used the HP generator as I have to be very careful about not blowing up the soundcard input and I am still sorting out my methodologies to ensure that I don't.
I am confident that the results will improve with the FFT software's internal generator (the stuff above 8 khz in particular).
Best wishes,
Susan.
Output Transformer Spec Update
Dear All,
Added Sowter information to this page.
http://www.susan-parker.co.uk/zeus-out-tx-75w.htm
And started on a page for construction information, notes and hints at:
http://www.susan-parker.co.uk/zeus-construction.htm
Best wishes,
Susan.
Dear All,
Added Sowter information to this page.
http://www.susan-parker.co.uk/zeus-out-tx-75w.htm
And started on a page for construction information, notes and hints at:
http://www.susan-parker.co.uk/zeus-construction.htm
Best wishes,
Susan.
Hi darkmoebius,
I hope you are keeping well.
Thanks.
I don't know what happend, but all is now working again.
I will be putting up more detail construction info, pics and better schematics etc. for the amplifiers during the next 7 to 10 days.
Best wishes,
Susan.
P.S.
I now have a 16 million point FFT software update to try out (previously it was only 1 million points). Guess who is a happy person
I hope you are keeping well.
darkmoebius said:The new additions to your website are great, especially the greater construction and parts descriptions
Thanks.
I don't know what happend, but all is now working again.
I will be putting up more detail construction info, pics and better schematics etc. for the amplifiers during the next 7 to 10 days.
Best wishes,
Susan.
P.S.
I now have a 16 million point FFT software update to try out (previously it was only 1 million points). Guess who is a happy person
Hello Susan,
I'm very interested in putting together a Zeus, and I'm curious whether some pieces I have lying around could be pressed into service.
For output transformers, I'm wondering about some Tannoy THD 60 transformers I have that come from CMS8 ceiling units for stepping down 100V signals. They claim to handle 180W program, and they have input taps for 7.5W, 15W, 30W, 60W, and 120W. I imagine these are multiple taps on a single winding.
If impedance equals voltage squared over power, I believe this translates to impedances of 1333, 666, 333, 166.5, and 83.25 ohms.
Do these appear to work, and which impedance would be best? Or would it depend more on the primary inductance, (which I don't really know how to measure)? I recognize they're not quad-filar wound, but might they still pass respectable bandwidth, intended as they are for audio?
Thanks,
Dart
I'm very interested in putting together a Zeus, and I'm curious whether some pieces I have lying around could be pressed into service.
For output transformers, I'm wondering about some Tannoy THD 60 transformers I have that come from CMS8 ceiling units for stepping down 100V signals. They claim to handle 180W program, and they have input taps for 7.5W, 15W, 30W, 60W, and 120W. I imagine these are multiple taps on a single winding.
If impedance equals voltage squared over power, I believe this translates to impedances of 1333, 666, 333, 166.5, and 83.25 ohms.
Do these appear to work, and which impedance would be best? Or would it depend more on the primary inductance, (which I don't really know how to measure)? I recognize they're not quad-filar wound, but might they still pass respectable bandwidth, intended as they are for audio?
Thanks,
Dart
I got some old car speakers with little impedance amps built on to the magnet assy. 2 of these speakers. One speaker was messed up, but I kept the amplifiers.
60W @ 4ohms was their rating.
The output transformers on these have no secondary, but instead the speaker is connected across the whole primary, while 2 NPN darlingtons drive the two halves of the transformer.
The peak output voltage is double the supply voltage (13.8V)
They are VERY loud. Even off of a 6V lantern battery, they played loud.
I'm going to take the two amps I have and build them on to a new PCB, and make a simple stereo amplifier.
60W @ 4ohms was their rating.
The output transformers on these have no secondary, but instead the speaker is connected across the whole primary, while 2 NPN darlingtons drive the two halves of the transformer.
The peak output voltage is double the supply voltage (13.8V)
They are VERY loud. Even off of a 6V lantern battery, they played loud.
I'm going to take the two amps I have and build them on to a new PCB, and make a simple stereo amplifier.
Hi Dartagnan,
Thank you for your post and interest.
If you can email me with more specs etc I will have a ponder and get back to you (may take a couple of days).
I have tried these myself originally but they generally don't have symetrical windings.
You could however try running using just the speaker side windings on a pair of transformers - effectivly bridged single ended.
Has been seen to work - can't remember the post number but if you look through this thread there is a schematic.
Can you rewind the transformers? Probably your best bet. Tedious if it's all welded together but not any more than winding a toroid.
Otherwise the mains torroid low voltage inding pair seems to be a good starting point for the output, and has adequate bandwidth, without incuring large costs.
Note the distortion figures though - compare the Zeus 2:1 and 4:1 ratios.
Hope this helps.
Best wishes,
Susan.
Thank you for your post and interest.
Dartagnan said:
If you can email me with more specs etc I will have a ponder and get back to you (may take a couple of days).
I have tried these myself originally but they generally don't have symetrical windings.
You could however try running using just the speaker side windings on a pair of transformers - effectivly bridged single ended.
Has been seen to work - can't remember the post number but if you look through this thread there is a schematic.
Can you rewind the transformers? Probably your best bet. Tedious if it's all welded together but not any more than winding a toroid.
Otherwise the mains torroid low voltage inding pair seems to be a good starting point for the output, and has adequate bandwidth, without incuring large costs.
Note the distortion figures though - compare the Zeus 2:1 and 4:1 ratios.
Hope this helps.
Best wishes,
Susan.
Confirmation on Affirmation
Hi Susan-Parker MIEE
The amp is now under serious testing condition as follows.
Input Signal 100Hz sinewave
Load 2 Ohms heater element
duration 6Hours Continous testing.
Input Stage Consists of:
Dual Differential input Line Driver Balanced with V swing at 15 Volts
regards
Workhorse Technologies
Hi Susan-Parker MIEE
The amp is now under serious testing condition as follows.
Input Signal 100Hz sinewave
Load 2 Ohms heater element
duration 6Hours Continous testing.
Input Stage Consists of:
Dual Differential input Line Driver Balanced with V swing at 15 Volts
regards
Workhorse Technologies
Thanks for the replay, Susan.
Unfortunately, I can find no more specs on the THD 60 in Tannoy's literature. Yes, the laminations are welded and would require substantial grinding to seperate.
What made me think these transformers might be usable in a Zeus was that the wattage taps seemed to indicate they would lend themselves to split primaries. For example, using the common tap as the negative and the 60W tap as the positive, grounding the 120W tap would yield two 83-ohm primaries. Lower wattage taps would yield higher impedances.
But you have experimented with these transformers already? When you say they generally don't have symmetrical windings, do you mean for example that the 120W tap doesn't have exactly half the turns of the 60W tap?
Sorry about the basic questions, but I don't have means of testing (or much know-how, really. )
Thanks,
Dart
Unfortunately, I can find no more specs on the THD 60 in Tannoy's literature. Yes, the laminations are welded and would require substantial grinding to seperate.
What made me think these transformers might be usable in a Zeus was that the wattage taps seemed to indicate they would lend themselves to split primaries. For example, using the common tap as the negative and the 60W tap as the positive, grounding the 120W tap would yield two 83-ohm primaries. Lower wattage taps would yield higher impedances.
But you have experimented with these transformers already? When you say they generally don't have symmetrical windings, do you mean for example that the 120W tap doesn't have exactly half the turns of the 60W tap?
Sorry about the basic questions, but I don't have means of testing (or much know-how, really.
)Thanks,
Dart