Bias Test Points
- Thread starter Scott_F
- Start date
Quencho092
New member
Re: Bias Test Points
the new 65RI fender twin has access to balance and bias pots from under the chassis so you dont have to peek in, but the test points are inside so theres no big deal...
I'm going to have to get the bias checked when i get mine since ive heard reports that the factory bias could be as low as a mind numbing 19mA!!!!!!!!!!!!
the new 65RI fender twin has access to balance and bias pots from under the chassis so you dont have to peek in, but the test points are inside so theres no big deal...
I'm going to have to get the bias checked when i get mine since ive heard reports that the factory bias could be as low as a mind numbing 19mA!!!!!!!!!!!!
PUCKBOY99
Irish Flagologist
Re: Bias Test Points
I think it boils down to common sense....which seems to be lacking in abundance in todays society!
I'd no sooner open the electrical panel in my house & start poking around if I had no idea what I was doing......if you don't know what does what inside an amp, keep your d1ckbeaters out of there & take it to a tech!!!!
That said, it's a great option to have for those in the know. My amps are cathode biased, so it's cool for me.
I assume the question/poll is for your Celtic amps, no???
I would put them on there with a big bold disclaimer in the manual or included with the amp. Or if they're made to order, ask the prospective buyer if they want it or not.
I think it boils down to common sense....which seems to be lacking in abundance in todays society!
I'd no sooner open the electrical panel in my house & start poking around if I had no idea what I was doing......if you don't know what does what inside an amp, keep your d1ckbeaters out of there & take it to a tech!!!!
That said, it's a great option to have for those in the know. My amps are cathode biased, so it's cool for me.
I assume the question/poll is for your Celtic amps, no???
I would put them on there with a big bold disclaimer in the manual or included with the amp. Or if they're made to order, ask the prospective buyer if they want it or not.
Last edited:
Jeff Seal
New member
Re: Bias Test Points
Scott.....just a thought for you, and this is what I do on mine...(of course my amps usually run either 4 or 8 output tubes)..
By installing an individual bias pot for each output tube, the output section can be precision balanced, since even "matched sets" are often quite different in their current draw....
..as an example:
Ampeg SVT's require an almost exact match for the two trio's of 6550's in order to prevent the "weakest" tube from being destroyed.....(If they're not setup right, SVT's will destroy even the most durable of 6550's in less than 3 hours!) Thus they have a "bias balance" to match the current draw of both banks, but even this still requires matching within the banks.... individual bias pots would significantly help in this case......of course I don't think you're really planning on building SVT clones anytime soon, but the principle still applies for even two tubes..
...happy building!!!
Jeff Seal
Scott.....just a thought for you, and this is what I do on mine...(of course my amps usually run either 4 or 8 output tubes)..
By installing an individual bias pot for each output tube, the output section can be precision balanced, since even "matched sets" are often quite different in their current draw....
..as an example:
Ampeg SVT's require an almost exact match for the two trio's of 6550's in order to prevent the "weakest" tube from being destroyed.....(If they're not setup right, SVT's will destroy even the most durable of 6550's in less than 3 hours!) Thus they have a "bias balance" to match the current draw of both banks, but even this still requires matching within the banks.... individual bias pots would significantly help in this case......of course I don't think you're really planning on building SVT clones anytime soon, but the principle still applies for even two tubes..
...happy building!!!
Jeff Seal
STRATDELUXER97
Stratoblaster Tone Meister
Re: Bias Test Points
Doug Hoffman was doing this on all of his amps back in and around 93 when I used to hang with him at his shop in Sarasota....His amps were so meticulous,shame it didn't take off for him...He's no slouch to selling amp related parts these days though.. I learned about cathode biasing from Doug and from a 2 hour conversation with Ken Fischer(A guy totally against using the "crossover notch" method of biasing amps...LOL
Jeff Seal said:Scott.....just a thought for you, and this is what I do on mine...(of course my amps usually run either 4 or 8 output tubes)..
By installing an individual bias pot for each output tube, the output section can be precision balanced, since even "matched sets" are often quite different in their current draw....
..as an example:
Ampeg SVT's require an almost exact match for the two trio's of 6550's in order to prevent the "weakest" tube from being destroyed.....(If they're not setup right, SVT's will destroy even the most durable of 6550's in less than 3 hours!) Thus they have a "bias balance" to match the current draw of both banks, but even this still requires matching within the banks.... individual bias pots would significantly help in this case......of course I don't think you're really planning on building SVT clones anytime soon, but the principle still applies for even two tubes..
...happy building!!!
Jeff Seal
Doug Hoffman was doing this on all of his amps back in and around 93 when I used to hang with him at his shop in Sarasota....His amps were so meticulous,shame it didn't take off for him...He's no slouch to selling amp related parts these days though..
I learned about cathode biasing from Doug and from a 2 hour conversation with Ken Fischer(A guy totally against using the "crossover notch" method of biasing amps...LOLSimilar threads
