I've got an amp in which one of the upgrades was 4 x Holco H2 1r5 in series (whoops! parallel) for each transistor. Each channel has 4 transistors. I didn't buy them at the time but used non-inductive wire-wounds (1 x 0r33 for each transistor).
Obviously these are no longer available (or rare as rocking horse doodoos),
what are the best currently available alternatives (without spending silly money) for these, either 4 x 1r5 or 1 x 0r33 that would make a difference to the sound quality.
Obviously these are no longer available (or rare as rocking horse doodoos),
what are the best currently available alternatives (without spending silly money) for these, either 4 x 1r5 or 1 x 0r33 that would make a difference to the sound quality.
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In one of my recent power amp PCB designs I replaced these 5W non-inductive resistors with SMD resistors in parallel. 1-ohm 2512 size 2W rated, 3 in parallel for 0.33, or 4 for 0.25. In your case perhaps a hand cut small piece of PCB as a mounting carrier will do. Just a thought.
http://www.vishay.com/docs/31801/mra.pdf
Mills made one of the better wirewounds; they were acquired a few years ago by Vishay, which has made a habit of buying well-known component manufacturers.
By my book, a low temperature coefficient (Tc) is very desirable in resistors. Look for 1% or better tolerance; the cheap wirewounds may be 10% and have very high Tc. It's not usually that critical a concern in amplifier design, but I have stocked up on better quality parts when I can find them at a fair price.
I'd have to see the schematic to understand why four >series< resistors would be used in this way; did you mean to say "parallel"? In output stages, emitter resistors are usually less than an ohm in value and are wirewound for heat dissipation. The squarish cement cased types usually are lower quality (but not always).
Mills made one of the better wirewounds; they were acquired a few years ago by Vishay, which has made a habit of buying well-known component manufacturers.
By my book, a low temperature coefficient (Tc) is very desirable in resistors. Look for 1% or better tolerance; the cheap wirewounds may be 10% and have very high Tc. It's not usually that critical a concern in amplifier design, but I have stocked up on better quality parts when I can find them at a fair price.
I'd have to see the schematic to understand why four >series< resistors would be used in this way; did you mean to say "parallel"? In output stages, emitter resistors are usually less than an ohm in value and are wirewound for heat dissipation. The squarish cement cased types usually are lower quality (but not always).
Not really keen on SMD types if I can avoid it, the pcb is already drilled for 4 through hole types. What make of SMD resistors did you use?
Sorry Damon, that should have been in parallel - senior moment!
The Holco H2 originally specified were very low tolerance and temperature coefficient hence their popularity.
I'm looking for recommendations for similar resistors/ brands and where to source them. The reasoning behind using 4 (in parallel!) was to get the required wattage with the benefits as an alternative to wirewounds which I have already installed.
I've searched the internet and can't find anybody who sells a 1 or 2 watt in 1r5 preferably well regarded for audio use.
Sorry Damon, that should have been in parallel - senior moment!
The Holco H2 originally specified were very low tolerance and temperature coefficient hence their popularity.
I'm looking for recommendations for similar resistors/ brands and where to source them. The reasoning behind using 4 (in parallel!) was to get the required wattage with the benefits as an alternative to wirewounds which I have already installed.
I've searched the internet and can't find anybody who sells a 1 or 2 watt in 1r5 preferably well regarded for audio use.
Search Ebay; I've bought 1% metal film 1 watt resistors in the 0.39 ohm range from a vendor there that seem to be adequate quality, although I think they are magnetic. I'd go with the Mills, though, just to keep the installation simple.
I sometimes buy from Michael Percy; write and ask if he can get the specific value you want. PRP is a good manufacturer that he stocks, and you can't go wrong with Vishay/Dale. He also stocks Mills 5 watt wirewounds that are compact for their wattage rating. A quality wirewound is the equal in quality to any metal film, and even bulk metal foil.
http://www.percyaudio.com/Catalog.pdf
I sometimes buy from Michael Percy; write and ask if he can get the specific value you want. PRP is a good manufacturer that he stocks, and you can't go wrong with Vishay/Dale. He also stocks Mills 5 watt wirewounds that are compact for their wattage rating. A quality wirewound is the equal in quality to any metal film, and even bulk metal foil.
http://www.percyaudio.com/Catalog.pdf
Holco are still readily available, here's an example
H82K0BYA | TE Connectivity HOLCO Series Axial Metal Film Resistor 2kΩ 0.1% 0.25W 15ppm/C | TE Connectivity
Trying to find the mills wirewounds in 1r5 or 0r33 from somewhere that either stocks in uk or ships to uk.
Also looking at the caddock resistors.
I'm going to contact Hificollective and see what they can do.
The Holco resistors are not available in the H2 (1 watt) from there unfortunately.
Keep up the suggestions
Thanks
Anjum
Also looking at the caddock resistors.
I'm going to contact Hificollective and see what they can do.
The Holco resistors are not available in the H2 (1 watt) from there unfortunately.
Keep up the suggestions
Thanks
Anjum
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