Since you listen in the near field you will want the lowest noise possible from the amp. On my builds there was a bit of hum until I replaced the 150 ohm, 5 watt resistor in the power supply with a Hammond 156R choke. They were dead quiet with the choke. Noticeably much more quiet than some of my significantly more expensive commercial amps.
S.
S.
Which type should be used for the load resistors? With the existing lists of parts, metal oxide layer, metal film and wire are suggested. Are there any special recommendations here? 😕
My preference when it comes to resistors (inset large grain of salt if you wish) is to use carbon film for 1 watt or lower duties except if 1% tolerance is required then I use metal film. For over 1 watt I'll use metal film if at all possible. Some people like to steer clear of metal oxide types in audio applications as much as possible. When wattage requirements necessitate wirewound resistors try to use ones with the lowest inductance possible, though the lower inductance types generally cost more. I don't get bent out of shape about wirewound inductance if it's used in a power supply. There a little inductance might do some good. I'm fairly agnostic when it comes to resistor types in audio circuits though I'm a bit fussier in the front end of a phono stage where injudicious selection can have noise consequences.
Hi Steve,
thank you for the informations.
I'm considering trying a tube amp too.
As OPT for the 'spp' I wanted to use the Hammond 1650F.
thank you for the informations.
I'm considering trying a tube amp too.
As OPT for the 'spp' I wanted to use the Hammond 1650F.
I find carbon film tends to drift over time so I prefer to use metal film or oxide types when possible, noninductive wirewound when I need more wattage.
The 1650F worked very well for me in this application. The Hammond 272JX works well for power duties but the slightly less expensive 272HX should be fine too. I don't know if you've been following along but I recommend using a choke in the power supply. It killed the last bit of hum in the output and the Hammond 156R only costs abut 15 bucks.
Fist part of build series here: https://wallofsound.ca/audioreviews/amplification/diy-el84-amp-update/
Fist part of build series here: https://wallofsound.ca/audioreviews/amplification/diy-el84-amp-update/
I've been following the whole thread. I will consider the Hammond 156R.
I am in Germany and need 230V and cannot use the 272JX/HX. The Marshall TT-MA36 transformer mentioned above or the Hammond 273HX should probably be considered.
I am in Germany and need 230V and cannot use the 272JX/HX. The Marshall TT-MA36 transformer mentioned above or the Hammond 273HX should probably be considered.
Hammond offers the 300 series that can be wired for 240 volts on the primary. There are 372HX and 372JX models. Hammonds are likely quite expensive in Europe due to shipping costs. This one mentioned earlier by Ketje looks promising and not expensive. https://www.tube-town.net/ttstore/tt-ma36-36-watt-netztransformator.html
I have gone through all the documents from Wall of Sound for the 'SPP'. For section 4 'Power Switch Wiring' I created the following illustration.
I hope I understood everything correctly! Maybe the experts could take a look.
Another question: Is there anything special to consider when arranging the transformers?
Thank you in advance
I hope I understood everything correctly! Maybe the experts could take a look.
Another question: Is there anything special to consider when arranging the transformers?
Thank you in advance
Attachments
Hi Jacques,
I don't have a chassis yet. Everything is still in preparation.
Frank
I am a good customer there but at the moment all their alu chassis are back ordered 4 to 6 months.
I really want to tell you to look for broken amps on the second-hand market, that's often where I find my chassis.
(that's how I bought a remote Hitone H300 by chance in a modern chassis a few years ago...)
(that's how I bought a remote Hitone H300 by chance in a modern chassis a few years ago...)
