Besides the wonky leads (I finally got a tool to make clean bends much easier) on the resistors, does anything seem incorrect? I did my best to double check each one with a meter before I placed it on the board, so I feel the values are correct. My main concern is using the wrong type of resistor somewhere on the board.
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Thanks! The different types of resistors (carbon, film, ceramic, metal foil, wirewound, etc) had me concerned that I might use the wrong type. I appreciate you taking a look at it!
Here it is now, I am waiting for the diodes and constant current source ICs to arrive so I can finish up, I also left the two connectors near the diodes and CCS off the board, I will put them on at the same time. Then hopefully music plays and no fireworks!
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Are R17 and R27 different types? They both appear to be Ohmite branded, but of a different series. Both of these resistors play the exact same role, but R17 is for the right channel while R27 is for the left channel. Different types of resistors in this location could lead to a channel imbalance.
I also noticed that you used what appear to be several carbon composition resistors. Is there a particular reason for this?
Carbon comp resistors do have their place due to their non-inductive nature, but they are well known to have a very large resistance drift over time. Carbon comps are fine for grid and gate stoppers, but due to their large drift they are usually not used anywhere else in an audio circuit.
Did you already have your carbon comp resistors just lying around waiting to be used or did you order them specifically for this build?
I also noticed that you used what appear to be several carbon composition resistors. Is there a particular reason for this?
Carbon comp resistors do have their place due to their non-inductive nature, but they are well known to have a very large resistance drift over time. Carbon comps are fine for grid and gate stoppers, but due to their large drift they are usually not used anywhere else in an audio circuit.
Did you already have your carbon comp resistors just lying around waiting to be used or did you order them specifically for this build?
I didn't know about the carbon comp drift issues. That's good to know, PDL.
I was going to say something about R17 and R27 but I didn't want to be the one making you start removing components you had already soldered. I figured, if they are both wire wound and their measured values are very close, then I don't see a problem with them being a different SKU. Although I suppose they might have considerably different inductance... (?)
I was going to say something about R17 and R27 but I didn't want to be the one making you start removing components you had already soldered. I figured, if they are both wire wound and their measured values are very close, then I don't see a problem with them being a different SKU. Although I suppose they might have considerably different inductance... (?)
I have a desolder station, so it should not be too painful to swap these out. I appreciate you folks looking the board over!!
Must be nice!
I hate desoldering so much I try to triple check everything before soldering it in place.
I hate desoldering so much I try to triple check everything before soldering it in place.
The amp would operate fine if you used all carbon comp resistors....for the most part a resistor is a resistor, as long as the resistance value and wattage is correct......but these days metal film resistors are usually used since they have lower noise and are more robust resulting in a "cleaner" sound.
Carbon comps are typically used for grid stopper resistors in hifi applications...since they are non-inductive they are less prone to oscillations.... the guitar tube amp guys use them all over the place for that vintage "tone". The old guitar amps from the 50's/60's have lots of them.
Carbon composition is a cylinder of carbon dust pressed together with leads shoved in each end. Metal film and wirewound resistors have metal film or wire wrapped around a non-conductive core with the leads welded to each end of the spiral. The spiral coil has some some inductance .....since it's a coil.
Carbon comps can sometimes fail by cracking from repeated thermal stress of power cycles since they are just pressed powder.
I think metal film is deposited on the core...then the spiral is laser cut...
Carbon comps are typically used for grid stopper resistors in hifi applications...since they are non-inductive they are less prone to oscillations.... the guitar tube amp guys use them all over the place for that vintage "tone". The old guitar amps from the 50's/60's have lots of them.
Carbon composition is a cylinder of carbon dust pressed together with leads shoved in each end. Metal film and wirewound resistors have metal film or wire wrapped around a non-conductive core with the leads welded to each end of the spiral. The spiral coil has some some inductance .....since it's a coil.
Carbon comps can sometimes fail by cracking from repeated thermal stress of power cycles since they are just pressed powder.
I think metal film is deposited on the core...then the spiral is laser cut...
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I am thinking about swapping R17 and R27 first, to the same exact type/brand/model/etc and seeing how it sounds. Then, if I don't like what I hear I could swap the carbon comps out. I went ahead and ordered all of them last night... I have another SSE board to use them on.
Who knows, maybe I will like the vintage tone of my random resistor recipe.
Oh yeah. I wondered if two would be enough! Why the deep regret? Is he out of them now??
No, I think George has more, but by the time I pay shipping, exchange, etc. it ends up double the cost - so I would have saved a lot of money just ordering 2 in the first place. Somehow throughout the roller coaster ride of my build, I ended up with enough parts and iron to build a second amp - I just don't have the board.