#183 Preamp only in a 1u rack case? Ideas?

[rogb]

I have a spare ex-Dlator 1U rack case and would like to build a #183 preamp only.
PAB and OD/Clean relays that I could use my current footswitch.
Any one done something similar?
I have seen info on back-to-back transformers to power v1 and 2, and relays.

So far this is what I've found:
http://ampgarage.com/forum/viewtopic.ph ... mp#p341622
http://ampgarage.com/forum/viewtopic.ph ... mp#p158560

I've really got into Class D power amps and would love a D style pre amp to run into one, as something different from my pedal board.

I think Demeter does a similar tube pre into class D power amp.
http://www.demeteramps.com/index.php?ro ... duct_id=95

[markusw]

Not in 1u rack case but in a (pretty large) stombox.
http://ampgarage.com/forum/viewtopic.php?f=4&t=5110

Is still in use, btw.

[rogb]

Thanks - that's very useful info

[martin manning]

This line of flat-pack transformers will fit in a 1u case and they are small and very inexpensive: http://www.hammondmfg.com/229.htm I would be inclined to use one with a 230V secondary and FWB rectifier for the HT, and another for a DC supply to power the filaments and relays. I think both could be 6VA.

[rogb]

This line of flat-pack transformers will fit in a 1u case and they are small and very inexpensive: http://www.hammondmfg.com/229.htm I would be inclined to use one with a 230V secondary and FWB rectifier for the HT, and another for a DC supply to power the filaments and relays. I think both could be 6VA.

They look perfect! Thank you.
So perhaps
229A12 6VA 12.6V C.T. @ 450ma 6.3V @ 900ma
229A230 6VA 230V C.T. @ 25ma 115V @ 50ma

[jam-mill]

You might try a toroidal transformer (just got one and it is a little snug in a 1U rack case and will require an alternative mounting method).

http://www.antekinc.com/as-05t160-50va- ... ansformer/

-jack

[rogb]

Thanks, I think the flat pack ones Martin pointed out will be best. They are cheap too!

I ran my 2nd gen preamp send into the 2x100w Class D via a stereo reverb pedal and it sounded very good.
I think the standalone preamp and small and light class D will be a good partnership.

I am only using 19v to power the class D at the moment and 16R speakers - with 36v and 8R there is a lot more power
from this little fella.

[M Fowler]

I have a set of those Hammond flat pack transformers to build a preamp as well. One of these days.

[norburybrook]

I feel partly responsible for this..............................

Class D????????? go wash your mouth out with soap and water.......


Marcus

[rogb]

I feel partly responsible for this..............................

Class D????????? go wash your mouth out with soap and water.......


Marcus

Yeah I'll get some soap for Sonny Landreth too, with his sacrilegious Demeter tube pre-amp/Class D power amp rig



I have run a lot of different stuff through this amp this week, even a MesaBoogie V-Twin pedal and all sounding good.
Maybe the speakers I am using just suit this rig?
Ix Celestion Creamback Neo 65w 16R in a pine open back cab and 1x SwampThang 16R in TL806. I have tried other combos but this one seems the best so far.

[martin manning]

So perhaps
229A12 6VA 12.6V C.T. @ 450ma 6.3V @ 900ma
229A230 6VA 230V C.T. @ 25ma 115V @ 50ma

Best to go up to 12VA for the filaments, 229B12. Use Schottky diodes in a FWB, at least 4700uF for the reservoir, and definitely use a low drop-out 12V regulator.
For the HT, 229A230 will be fine with a FWB and a CRC reservoir: 220uF, 1k, 220uF; 350V caps. That will give very low ripple. You can adjust the 1k to dial the voltage in.

[rogb]

Thanks Martin, that's really useful advice!

[rogb]

So perhaps
229A12 6VA 12.6V C.T. @ 450ma 6.3V @ 900ma
229A230 6VA 230V C.T. @ 25ma 115V @ 50ma

Best to go up to 12VA for the filaments, 229B12. Use Schottky diodes in a FWB, at least 4700uF for the reservoir, and definitely use a low drop-out 12V regulator.
For the HT, 229A230 will be fine with a FWB and a CRC reservoir: 220uF, 1k, 220uF; 350V caps. That will give very low ripple. You can adjust the 1k to dial the voltage in.

1n5817 - would these be OK 20V 1A?
I'm going to run 5v Omrons so the usual 7805 regulator for this?

[martin manning]

I recommend going to 12V DC for filaments and using that same supply for 12V relays. 20V might be cutting it close for the diodes. 50V 1A would be better.

[rogb]

I recommend going to 12V DC for filaments and using that same supply for 12V relays. 20V might be cutting it close for the diodes. 50V 1A would be better.

Are you saying to run the filaments on the 12vDC as opposed to the 6.3 vAC that we normally use?
Could you recommend a Schottky that is suitable please? The nearest is a 40v 5819 that I can find.

I usually use 5v Omrons but I can see the logic in using 12v - I will change my Mouser project then and re-order the 7812 regs:D

Many thanks again for your insights.