Bogner XTC 25!

[dbsens]

When will these start selling? I’ve seen one on Reverb but it’s already sold. Will Sweetwater carry them?

 

[scottosan]

The tube layout doesn't seem to support it be s 1:1 lowered watt clone of the 101b, so I can only assume there are some significant differences in the preamp. I will also not that the mafic of the XTC is in the unique NFB circuit and o don't know how much of that carried over either

 

[Rdodson]

Scott - please explain the magic of the Ecstasy negative feedback/filtering/etc. I've tried to drill down but can't get it exactly right.

Seems to remind me of my original '68 SL in how the power amp feels, but I could be wrong.

Thanks!

 

[scottosan]

Scott - please explain the magic of the Ecstasy negative feedback/filtering/etc. I've tried to drill down but can't get it exactly right.

Seems to remind me of my original '68 SL in how the power amp feels, but I could be wrong.

Thanks!

stand and feedback on Marshalls have been just a resistor and all of the frequencies are fees back equally. Then came along the variable depth mods seen on Soldanos and others that feed back some frequencies at a different levels. The frequency is controlled by the value of the cap. The more of a frequency fed back, the less gain in that frequency. Thus turning up a depth pot reduces the amount of the frequency fed back which increases the gain of those frequencies. Higher frequencies are being bypasses by the cap while the lower frequencies are not, this the improved lowend. Bogners NFB is much different and more complex network. I'd have to pull the schems of my Mac though to post

 

[kdmay]

Scott - please explain the magic of the Ecstasy negative feedback/filtering/etc. I've tried to drill down but can't get it exactly right.

Seems to remind me of my original '68 SL in how the power amp feels, but I could be wrong.

Thanks!

stand and feedback on Marshalls have been just a resistor and all of the frequencies are fees back equally. Then came along the variable depth mods seen on Soldanos and others that feed back some frequencies at a different levels. The frequency is controlled by the value of the cap. The more of a frequency fed back, the less gain in that frequency. Thus turning up a depth pot reduces the amount of the frequency fed back which increases the gain of those frequencies. Higher frequencies are being bypasses by the cap while the lower frequencies are not, this the improved lowend. Bogners NFB is much different and more complex network. I'd have to pull the schems of my Mac though to post

Not really. It’s just a 3 way switch of fixed depth settings with one option being no depth and an assignable presence circuit. What makes this so unique?

 

[scottosan]

Scott - please explain the magic of the Ecstasy negative feedback/filtering/etc. I've tried to drill down but can't get it exactly right.

Seems to remind me of my original '68 SL in how the power amp feels, but I could be wrong.

Thanks!

stand and feedback on Marshalls have been just a resistor and all of the frequencies are fees back equally. Then came along the variable depth mods seen on Soldanos and others that feed back some frequencies at a different levels. The frequency is controlled by the value of the cap. The more of a frequency fed back, the less gain in that frequency. Thus turning up a depth pot reduces the amount of the frequency fed back which increases the gain of those frequencies. Higher frequencies are being bypasses by the cap while the lower frequencies are not, this the improved lowend. Bogners NFB is much different and more complex network. I'd have to pull the schems of my Mac though to post

Not really. It’s just a 3 way switch of fixed depth settings with one option being no depth and an assignable presence circuit. What makes this so unique?

Well, he's using 470p and 1m on the loose setting, and on the Medium setting I recall it switching in a 220k in parallel and assignable. Most depth controls is between 2200 and 4700pf and dont sound as good with 1m in parallel. The closest implementation I've seen is in Cameron's punch, but with variable restistance An XTC preamp without the power section falls flat

 

[kdmay]

Well, he's using 470p and 1m on the loose setting, and on the Medium setting I recall it switching in a 220k in parallel and assignable. Most depth controls is between 2200 and 4700pf and dont sound as good with 1m in parallel. The closest implementation I've seen is in Cameron's punch, but with variable restistance An XTC preamp without the power section falls flat

All true, I just don’t think it’s complex or unique. He just choose the right RC values to suit the amp. In his case it seems like he was chasing a little less bottom end through the NFB section, given the large PI output couplers. So more of a lower mid boost in some regards.

Whereas the Uberschall does have a complex and unique NFB section. It’s what makes that amp, as coupling the preamp into a normal Marshall power section and it doesn’t sound particularly great.