Adequate OPT's for >200Hz application

[sprinter]

I'm trying to figure out a good configuration for a bi-amp'd active crossover system which would drive a two-way system composed of a high efficiency full-range driver and a 15" augie, both in open baffles.

My idea is to drive the full-rangers with a Simple SE amp and the woofer with a more cost effective SS. Would I be correct that the full range component would most benefit from the traits of the SE amp and that the woofer would be less critical in that regard?

Second, could I get away with a cheaper OPT on the Simple SE because it is no longer important to have good low frequency response since that responsibility would be crossed over to the woofer at about 200 Hz?

Any specific recommendations are welcome. Obviously I'm trying to save money here, but don't want to sacrifice too much either. It also would be nice to save chassis real estate and weight.

Thanks.

[boywonder]

What output tubes are you planning on using in the Simple SE? Triode or UL?

I'd start with Trioded EL34's.....Of course this all depends on the sensitivity of your FR drivers and your listening habits.

For Budget transformers, are you considering Edcor XSE/GXSE series?

[nightanole]

You could get away with the 10 watt since you are not playing less then 200hz, however the 15 watt are less then 10 bucks a pair more...


EDCOR Electronics Corporation. XSE Series Output Transformers

[sprinter]

Originally Posted by boywonder

What output tubes are you planning on using in the Simple SE? Triode or UL?

I'd start with Trioded EL34's.....Of course this all depends on the sensitivity of your FR drivers and your listening habits.

For Budget transformers, are you considering Edcor XSE/GXSE series?

Thanks to both of you. I haven't decided on any components yet. I figure that the full-rangers would be around 94 dB (Foxtex, Audio Nirvana, etc.) and I don't rattle the walls (although the room is a rather large living room), so probably I wouldn't need more than maybe four watts pc if that. I'm most interested in mid range qualities. image, stage, etc, over power. Any tube recommendations would be appreciated. I do have some technical abilities, but this is my first audio build and I want to get it right.

The Edcor's sound just fine and would fit budget great. Is this family what most folks go for on these amps?

[tubelab.com]

For an Simple SE that is used with a sub or otherwize doesn't need to go below 100Hz or so, use the Edcor XSE 15-8-5K. Several users (including myself) have already done this. This little transformer will handle any of the popular audio tubes and work up to 35KHz or so. There may be some more expensive choices that work better, but these sound nice for About $30 each.

Tubes, the trioded EL34 will give you 6 or 7 watts and probably sounds the best overall for this application.

[boywonder]

Originally Posted by sprinter

I wouldn't need more than maybe four watts pc if that. I'm most interested in mid range qualities. image, stage, etc, over power. Any tube recommendations would be appreciated.

EL34 in triode, with Edcor 5K:8 XSE or GXSE transformers.

Edcors come in three flavors XSE ($), GXSE ($$), and CXSE ($$$). The XSE series are naked, ie no end bells; the others have end bells. The larger power rated transformers are physically larger and will provide wider bandwidth (mostly more bass), which you may not need in this application.

The primary impedance of the output transformer is somewhat dependant on what output tubes you are running. Here are a couple of relevent links:

Check out the tables on the Tubelab page. You can see (triode) power out for either 3K or 5K transformers at various B+ voltages. El34/5K yields 4-6 w depending on B+ voltage.


EDCOR Electronics Corporation. Single Ended Tube Output Transformers


Tubes & Transformers

[sprinter]

Originally Posted by tubelab.com

For an Simple SE that is used with a sub or otherwize doesn't need to go below 100Hz or so, use the Edcor XSE 15-8-5K. Several users (including myself) have already done this. This little transformer will handle any of the popular audio tubes and work up to 35KHz or so. There may be some more expensive choices that work better, but these sound nice for About $30 each.

Tubes, the trioded EL34 will give you 6 or 7 watts and probably sounds the best overall for this application.

Perfect. Thanks. Actually, according to the Edcor site, these are only about $20 ea. Fixed at 8 ohm, but that's okay for me.

I thought I saw somewhere that you can supply a "bag o' parts" for this build to populate the board. True? I don't have many components around any more, so something like that would be pretty useful if you do. BTW, I was glad to read on your site that you like to over-spec components. I've seen so many overheated resistors and blistered caps, scorched sockets, blackened switches, etc. even on stuff that's not that old, just cheaply made.

Thanks again.

[sprinter]

Originally Posted by boywonder

EL34 in triode, with Edcor 5K:8 XSE or GXSE transformers.

Edcors come in three flavors XSE ($), GXSE ($$), and CXSE ($$$). The XSE series are naked, ie no end bells; the others have end bells. The larger power rated transformers are physically larger and will provide wider bandwidth (mostly more bass), which you may not need in this application.

The primary impedance of the output transformer is somewhat dependant on what output tubes you are running. Here are a couple of relevent links:

Check out the tables on the Tubelab page. You can see (triode) power out for either 3K or 5K transformers at various B+ voltages. El34/5K yields 4-6 w depending on B+ voltage.


EDCOR Electronics Corporation. Single Ended Tube Output Transformers


Tubes & Transformers

Thanks, boywonder. These are interesting reads. I would like to make this thing look as good as possible. I have a nice chassis about 12" x 10" from an old satellite receiver system that I want to use, with components top-side, except for the board. Are there any covers one could put over the transformers just to make them look more high-end?

Also, is it okay to put the board inside a closed chassis without overheating anything? There would be holes for the tubes, but that's about all. All xfmrs and tubes would be exposed.

[boywonder]

Originally Posted by sprinter

Are there any covers one could put over the transformers just to make them look more high-end?

Also, is it okay to put the board inside a closed chassis without overheating anything? There would be holes for the tubes, but that's about all. All xfmrs and tubes would be exposed.

Apply the cash you'd spend on covers for XSE series to upgrade to the GXSE series......or see if the dims on the XSE series will allow under the hood mounting.

Ventilation is good. You can make the holes for the tube sockets on the chassis a bit oversize; that does two things, allows for some air flow, and makes aligning the tube sockets and the PCB mounting holes a lot easier.