Nice Keenan. Vinyl with that Sowter amp with that menacing mains transformer looks the works. Speakers looks good too.
Thanks! Hope you are still enjoying your new amp
L0rdGwyn's DIY Audio
- Thread starter L0rdGwyn
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Thanks! Hope you are still enjoying your new amp
UntilThen
Headphoneus Supremus
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Thanks! Hope you are still enjoying your new amp
Enjoying it so much I need to check in to AA. Amps Anonymous. I've no doubt the wonderful sonics that I hear are attributed to Sowter irons.
Yes but the rest is very important too! All working in concert
After building my 801A amp, I have no desire to design another speaker amp for a long, long time. I still have a small collection of HK54 transmitting triodes for an even more ridiculous amplifier, but who knows if it will ever get done (still, I keep an eye out for more...).
I opened my 801A amp to make some minor adjustments yesterday, holy crap this was a complicated build! Glad it is behind me lol.
UntilThen
Headphoneus Supremus
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Yes but the rest is very important too! All working in concert
Oh no doubt about it. Tomas did a splendid job on Odyssey. Your interior is nice and so is Odyssey's. A lot goes in there. A lot of switches... speakers, impedance, triode/UL, input selector switches, feedback on/off for EL11, 6sl7 or EL11 switches. Yamamoto's sockets looks good on the other side.
Are those Duracell batteries in there? How often do you have to change it?
Oh no doubt about it. Tomas did a splendid job on Odyssey. Your interior is nice and so is Odyssey's. A lot goes in there. A lot of switches... speakers, impedance, triode/UL, input selector switches, feedback on/off for EL11, 6sl7 or EL11 switches. Yamamoto's sockets looks good on the other side.
Are those Duracell batteries in there? How often do you have to change it?
They power the whole amplifier, so every 5 minutes.
Just kidding
similar to the DAC, the batteries act as a voltage reference for biasing, they are not drained at all in ordinary use. So only changed at the shelf life of the battery, which is 10 years for AA.Gotta cram a lot inside of these complex amplifiers! Getting the layout right is often the hardest part, I'm sure Thomas' layout is splendid.
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All is truly ready now for the DAC prototype.
I added in the I/V transformers, output caps, RCA outputs, output protection zener diodes. DAC isolation transformer is in place as well.
I fed a ballpark signal into the I/V transformer primary - obviously will not emulate the PCM56 current output well, but for the sake of checking that all is working as intended.
Here is a 1kHz sine wave at the RCA output, input signal to the I/V transformer is 0.19Vpeak-peak.
When the digital components are in place, will need to adjust the secondary resistor to find a balance between output distortion and output signal, aiming for 2Vrms.
From a build standpoint, really nothing else to do now but wait. In the meantime, I'll probably nail down how I will be testing the DAC.
I added in the I/V transformers, output caps, RCA outputs, output protection zener diodes. DAC isolation transformer is in place as well.
I fed a ballpark signal into the I/V transformer primary - obviously will not emulate the PCM56 current output well, but for the sake of checking that all is working as intended.
Here is a 1kHz sine wave at the RCA output, input signal to the I/V transformer is 0.19Vpeak-peak.
When the digital components are in place, will need to adjust the secondary resistor to find a balance between output distortion and output signal, aiming for 2Vrms.
From a build standpoint, really nothing else to do now but wait. In the meantime, I'll probably nail down how I will be testing the DAC.
Not much is going according to plan this week!
My Audial S5 as held up in US customs - I provided the paperwork and it was released, but it has not moved for two days despite my best efforts. Hopefully it arrives by the weekend.
My PCM56 DAC PCBs have shipped, but projected arrival date is Tuesday, when I go back to work. They have arrived early in the past, so I'm hopeful they will get here Monday and I can finish my prototype.
Some semi good news - the UK distributor from which I ordered my PCM56 DAC transformers made a mistake - they told me to keep the stock with a refund. So I now have some spare transformers for another project.
This DAC designing business has opened up a whole can of worms - I expect I will be experimenting with DAC designs for some time. As such, I'm going to design another one, a more simple and straightforward design compared to the PCM56, based on the Philips TDA1387T. This is similar to the TDA1545, which itself is something of an improved TDA1543.
I bought 30 pieces for $11.
A major advantage of this chip over the TDA1543 (which is very popular in the DIY world) is its very minimal power supply requirements - around 6mA per chip, as opposed to 50mA of the TDA1543. This keeps the power supply small without the need for heatsinking, meaning several of these chips can be paralleled. That's what I intend to do, could also consider running them in differential mode (balanced). Plan to run from one of the transformers above with SPDIF input (I2S protocol), the goal being to make a very compact NOS R2R DAC.
We'll see where that goes, otherwise I have been doing work on my next amplifier.
The wait continues for DAC stuff
My Audial S5 as held up in US customs - I provided the paperwork and it was released, but it has not moved for two days despite my best efforts. Hopefully it arrives by the weekend.
My PCM56 DAC PCBs have shipped, but projected arrival date is Tuesday, when I go back to work. They have arrived early in the past, so I'm hopeful they will get here Monday and I can finish my prototype.
Some semi good news - the UK distributor from which I ordered my PCM56 DAC transformers made a mistake - they told me to keep the stock with a refund. So I now have some spare transformers for another project.
This DAC designing business has opened up a whole can of worms - I expect I will be experimenting with DAC designs for some time. As such, I'm going to design another one, a more simple and straightforward design compared to the PCM56, based on the Philips TDA1387T. This is similar to the TDA1545, which itself is something of an improved TDA1543.
I bought 30 pieces for $11.
A major advantage of this chip over the TDA1543 (which is very popular in the DIY world) is its very minimal power supply requirements - around 6mA per chip, as opposed to 50mA of the TDA1543. This keeps the power supply small without the need for heatsinking, meaning several of these chips can be paralleled. That's what I intend to do, could also consider running them in differential mode (balanced). Plan to run from one of the transformers above with SPDIF input (I2S protocol), the goal being to make a very compact NOS R2R DAC.
We'll see where that goes, otherwise I have been doing work on my next amplifier.
The wait continues for DAC stuff
The Audial S5 has landed.
This DAC has just about any digital input you could ask for. Using the USB input runs the TDA1541A via Philips simultaneous data protocol, so that is the preferred connection for me. It even has direct I2S digital inputs over HDMI, so you could potentially run the output of a I2S output compatible CD transport directly into the DAC. You can even connect two of these DACs together for a four-channel USB setup. There are many other nifty connection features, but I'll leave it at that. Engineering!
Dual RCA outputs, one is cap coupled, the other is transformer coupled. There is also a chassis ground connection if needed.
Here is the famous. I won't show the rest of the interior (although there are many pictures of the inside from previous models online), but suffice to say it is impeccably well-built.
I have only been listening with the transformer-coupled outputs so far, over USB out of my Innuos server which operates as a Roon core, into my 801A amplifier to my Snells.
Pedja does state that the DAC will burn in over a couple of weeks, but first impressions are very good. My immediate feeling is this DAC is very resolving and uncolored, neutral yet musical, especially compared to my former SW1X DAC II which had a warm / euphonic lean to my ears, no doubt in part due to the tube output stage. But the S5 is completely devoid of audible noise, even with my amplifier at max volume without music playing (this would be an ear-destroying volume with 7W into the 92dB/W Snells).
This DAC is made from the marriage of subjective listening evaluation by the designer as well as sound engineering techniques and measurements - the DAC came with a slew of graphs showing its measured performance.
More listening / burning-in to be done, need to have a listen with headphones later today!
This DAC has just about any digital input you could ask for. Using the USB input runs the TDA1541A via Philips simultaneous data protocol, so that is the preferred connection for me. It even has direct I2S digital inputs over HDMI, so you could potentially run the output of a I2S output compatible CD transport directly into the DAC. You can even connect two of these DACs together for a four-channel USB setup. There are many other nifty connection features, but I'll leave it at that. Engineering!
Dual RCA outputs, one is cap coupled, the other is transformer coupled. There is also a chassis ground connection if needed.
Here is the famous. I won't show the rest of the interior (although there are many pictures of the inside from previous models online), but suffice to say it is impeccably well-built.
I have only been listening with the transformer-coupled outputs so far, over USB out of my Innuos server which operates as a Roon core, into my 801A amplifier to my Snells.
Pedja does state that the DAC will burn in over a couple of weeks, but first impressions are very good. My immediate feeling is this DAC is very resolving and uncolored, neutral yet musical, especially compared to my former SW1X DAC II which had a warm / euphonic lean to my ears, no doubt in part due to the tube output stage. But the S5 is completely devoid of audible noise, even with my amplifier at max volume without music playing (this would be an ear-destroying volume with 7W into the 92dB/W Snells).
This DAC is made from the marriage of subjective listening evaluation by the designer as well as sound engineering techniques and measurements - the DAC came with a slew of graphs showing its measured performance.
More listening / burning-in to be done, need to have a listen with headphones later today!
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Of course I am doing DIY stuff too - designing the power supply for my TDA1387T DAC. Going to go with a LDO regulator approach likely using SMD components on this one, power supply design is actually nearly done, need to work on the digital front end and I/V stage next...
Oh and my PCM56 PCBs should arrive tomorrow, so it is going to be a busy weekend.
Oh and my PCM56 PCBs should arrive tomorrow, so it is going to be a busy weekend.
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Looking forward to more impressions!!! Very interested to read your take on cap coupled vs. transformer coupled.
Considering DAC upgrade, and this one is on my short list of candidates...
Looking forward to more impressions!!! Very interested to read your take on cap coupled vs. transformer coupled.
Considering DAC upgrade, and this one is on my short list of candidates...
For sure! Will give it some time though for ears / parts to burn in.
Here are some really old transmitting triodes, Eimac 35TG from 1946. This is a near-equivalent to the HK54. I am slowly collecting these, if I ever build myself another speaker amplifier, it will be based on these transmitters, an A2 design making ~15W single ended.
The 35TG has a 5V 4A thoriated tungsten filament, the HK54 a 5V 5A filament. This would be one crazy ass amplifier, I have no desire to work on it now lol so I will just stow away these tubes for a few years probably.
Now those are a wee bit radioactive 
.
Tubes that glow even when they’re not switched on!!!
.Tubes that glow even when they’re not switched on!!!
Now those are a wee bit radioactive
Tubes that glow even when they’re not switched on!!!
Yup, that's fluorescence from uranium glass used to make metal to glass seals.
Plus the thoriated tungsten filaments…
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