Hello,
I have to obtain the power and output transformers for what will be my first amp project, built from a partial kit. I'm running into difficulty in locating transformers that match exactly what I need.
The amp is described as a push-pull, but the only output transformer available here in the states I've seen so far is described as being used with single-ended designs. I've attached the schematic from the E-Bay listing. The transformer I think may work is an Edcor GXSE15-8-3.5K. The connections look correct, and the primary winding resistance looks correct, though it's described as being used for single ended designs. The closes push-pull design output transformer Edcor lists is a GXPP15-8-5K-but the primary resistance is higher and it has additional leads on the primary side I wouldn't know what to do with. I'm thinking the schematic doesn't follow every neat and tidy convention when it comes to tube amp design.
Regarding the power transformer, the recommended spec is as follows (secondary side): 1X 280-0-280@100mA, 2X 3.15-0-3.15@1.5A, 1X 5V@ 3.5A, and 2X 2.5V@5.0A. Straight off it looks like the 2.5V (filament) supply is usuall supplied by a stand alone transformer, but the others (beyond the 280V supply, I'm not even sure what they're for!) are often packaged in the same transformer. My most fundamental question is how sensitive are the tubes to the specific voltage and current they receive? Would a 330-0-330 work ok? If the lower voltage components see a supply with greater current capability, is there a risk of burning anything out? I was always given to understand that no electrical component will use more current than it needs, however in playing around with some small stuff on PCBs recently I've learned that there are indeed 'dumb' components out there which if you do not provide current limiting resistance, will self destruct. I read something to this effect regarding the tube filament supply.
Thank you very much for your suggestions,
Rick
I have to obtain the power and output transformers for what will be my first amp project, built from a partial kit. I'm running into difficulty in locating transformers that match exactly what I need.
The amp is described as a push-pull, but the only output transformer available here in the states I've seen so far is described as being used with single-ended designs. I've attached the schematic from the E-Bay listing. The transformer I think may work is an Edcor GXSE15-8-3.5K. The connections look correct, and the primary winding resistance looks correct, though it's described as being used for single ended designs. The closes push-pull design output transformer Edcor lists is a GXPP15-8-5K-but the primary resistance is higher and it has additional leads on the primary side I wouldn't know what to do with. I'm thinking the schematic doesn't follow every neat and tidy convention when it comes to tube amp design.
Regarding the power transformer, the recommended spec is as follows (secondary side): 1X 280-0-280@100mA, 2X 3.15-0-3.15@1.5A, 1X 5V@ 3.5A, and 2X 2.5V@5.0A. Straight off it looks like the 2.5V (filament) supply is usuall supplied by a stand alone transformer, but the others (beyond the 280V supply, I'm not even sure what they're for!) are often packaged in the same transformer. My most fundamental question is how sensitive are the tubes to the specific voltage and current they receive? Would a 330-0-330 work ok? If the lower voltage components see a supply with greater current capability, is there a risk of burning anything out? I was always given to understand that no electrical component will use more current than it needs, however in playing around with some small stuff on PCBs recently I've learned that there are indeed 'dumb' components out there which if you do not provide current limiting resistance, will self destruct. I read something to this effect regarding the tube filament supply.
Thank you very much for your suggestions,
Rick