The DIY and audio equipment rut...... where to now?

[dsavitsk]

I think I am sold on the benefits of parafeed based on some of dsavitsk's stuff I have been reading, so that is certainly the direction I am heading..... I am trying to digest his L'espressivo projects right now, and think it might be worthwhile waiting for the DIY L'espressivo kit he and tomb are currently prototyping but building it P2P with better iron. And obviously Pete Millett's ECC99 SRPP that I mentioned earlier. But any other specific schematics you can point me to would be more than welcome!

I am certainly happy to help with schematics, ideas, or whatever else you need. The kit is basically a pared down version intended for beginners. But, if you are going to do it P2P, there are a number of things you might do differently -- better CCS, different tubes, a regulator before the CCS, tube rectifier, perhaps a SRPP or a mu follower instead of a solid state CCS (for the record, I don't think this is better, but it is different), etc.

Oh, and I happen to know of someone selling some Electra-Print 5K:32 parafeed transformers: FS: Electra-Print 5K:32 2.5W Parafeed Headphone Output Transformer - diyAudio

[Beefy]

I am certainly happy to help with schematics, ideas, or whatever else you need.

Thanks, that is a very kind offer. I hope that you don't come to regret it!

better CCS, different tubes, a regulator before the CCS, tube rectifier, perhaps a SRPP or a mu follower instead of a solid state CCS (for the record, I don't think this is better, but it is different), etc.

All options I have read about, some I understand, some not so much. But I'm certainly not above choosing moar tubez simply because they are pretty.

Oh, and I happen to know of someone selling some Electra-Print 5K:32 parafeed transformers: FS: Electra-Print 5K:32 2.5W Parafeed Headphone Output Transformer - diyAudio

I actually saw those already amongst many Google searches for parafeed and headphones. Hell of a lot cheaper than a pair of Sowters, so I'll definitely keep them in mind.

[Beefy]

Alright, as a bit of an intellectual exercise I have started investigating tube rectified PSU's. I simmed up the Torpedo/Sausage in PSUD2 based on the BOM posted here, the stated 275V B+ and some of my best-guesses from internal photos.

I figure 225VAC (I worked backwards to this), and I can't sim 1N5062 so I used a 1N4007 bridge rectifier. It looks like a CLCRC filter with 10

[manaox2]

Ooo, go Beefy!

Ah-hem, that came out funny.

[n_maher]

I'd try to get the capacitance in the last filter stage down a bit if you can, motor runs of that size (100uF) are brutal chassis work. And really, if you're going to tube-rectify the thing it'd be a sin to use electrolytic caps. :evil:

EDIT - and I'd go with the 5AR4 over the 5U any day, its semi-soft start is a welcome bonus.

[Beefy]

I'd try to get the capacitance in the last filter stage down a bit if you can, motor runs of that size (100uF) are brutal chassis work. And really, if you're going to tube-rectify the thing it'd be a sin to use electrolytic caps. :evil:

HEH, I've already started investigating motor run caps. The trump card is that I can increase the first filter cap to 40

[dBel84]

I know it is not a good reason to use the 5U4G over the 5AR4 but those coke bottle tubes are much prettier..dB

[n_maher]

I have yet to encounter a 5U* that had a rise time anything like a 5AR4 and I'd wager that I used just about all of them. Certainly the GA, GB and plain G did not in the Menace or HA-2. And yes, 68uF is a great target, although still a pretty big can.

[Beefy]

And yes, 68uF is a great target, although still a pretty big can.

Thankfully, I am more than happy to yield to the chief circular hole cutter. If this all goes ahead I will likely be lazy and go with one of the Hammond wood boxes with a FPE top plate.

[digger945]

I just got hold of a few Aerovox 24uF 400v (these say 50/60hz) from some shop light ballastes we just replaced with moar modern ones. They look to be 1.75" diam. by 4.125" long for the can, about 4.75" overall length including the connector tabs. *free if can be used*

Mine look a little longer than this one, otherwise identical.

Edited August 24, 2010 by digger945

[n_maher]

Thankfully, I am more than happy to yield to the chief circular hole cutter. If this all goes ahead I will likely be lazy and go with one of the Hammond wood boxes with a FPE top plate.

You can bet good $$ that I won't be cutting the holes for the motor run caps my 307A will be using!

And I think the 100uF/370VAC caps that I used for the outputs on the original Menace were roughly the size of a can of soda.

[Beefy]

HEH, fair call.

I'm also seeing that Solen polypropylene caps are surprisingly inexpensive and compact. 39

[Dusty Chalk]

And I think the 100uF/370VAC caps that I used for the outputs on the original Menace were roughly the size of a can of soda.

:drool:

Not because the 'can of soda' reference makes me thirsty, but because that amount of power reserve makes me ...well, drool.

[dsavitsk]

If you are doing a L'es style parafeed amp, those caps are really pretty incidental. The CCSes keep them completely isolated from the signal current loops and can provide up to something like 120dB of ripple rejection meaning that the ripple will be lower than anything you can probably measure. I'd use an electrolytic, and then put a small (0.1u to 1u) film bypass cap right at the CCS.

The problem with the Solens is that the big ones are a pain to mount.

Oh, and 5ar4 has a slower warm up than the 5u4 as the 5u4 is directly heated. Me, I prefer good sand rectifiers. Tube rectifier impedance is too high. In this amp, again because of the CCS isolation, it makes no difference.

[Beefy]

If you are doing a L'es style parafeed amp, those caps are really pretty incidental. The CCSes keep them completely isolated from the signal current loops and can provide up to something like 120dB of ripple rejection meaning that the ripple will be lower than anything you can probably measure. I'd use an electrolytic, and then put a small (0.1u to 1u) film bypass cap right at the CCS.

Oh, absolutely. Just seemed like something good to practice on until I collect a few more options for amp schematics.

Still looking closely at the ECC99 SRPP for inspiration as well, because the power supply for this sims at 9mV ripple. The resistor-loaded 12AU7 seems like it would benefit from ripple being lower, or from a CCS of course......

[Beefy]

I always knew how rectifiers worked, but never bothered with investigating it any deeper beyond calculating required secondary voltages into a bridge rectifier. So I Just found a really useful reference for transformer voltage conversions and current outputs here.

So Pete's 250VAC 130mA transformer into a capacitor loaded bridge rectifier results in 350VDC, but only 80.6mA DC current.

The hack I put together from a 500VAC 81mA transformer into a capacitor loaded full-wave rectifier results in 355VDC, and holds the same 81mA current.

Pretty snazzy, really. So much information to digest!

[dsavitsk]

So I Just found a really useful reference for transformer voltage conversions and current outputs here.

I was about to say that I'd trust technical transformer information from Hammond about as far as I could throw one of their power transformers. But, since they undersize the cores, I cold probably throw one pretty far

Try these articles -- the bottom two are on PS design

audioXpress - Track Listings - Audio Classroom Series

[kevin gilmore]

So both hammond and plitron are worthless...

You would think that companies making this stuff for the last 75 years would have a clue.

[dsavitsk]

So both hammond and plitron are worthless...

You would think that companies making this stuff for the last 75 years would have a clue.

Hammonds just don't meet their specs. If you try to run them at specified currents, the voltage sags, they hum, and they run on the verge of burning up. The 300's are better than the 200's, but neither are great.

[kevin gilmore]

And then you really abuse them like singlepower does, and they really do burn up.

[spritzer]

He didn't abuse them, he just unlocked a hidden feature...

[Beefy]

After much research I have learned a LOT, but I really am spending WAY too much effort on this when I don't have that much time and brain cycles to spare. I think I just need a mindless project to distract myself from my crappy job. So what I plan to do is build a Crack now, and a Torpedo/Sausage when it is released, to keep my hands busy. Between the two it will give me a taste of both OTL and transformer-coupled flavours. Once I've decided which flavour I like the best, I can sell them both to fund a much grander build from the ground-up.

So thanks for all the advice and inspiration. I will hopefully revisit this thread in a few months......

[Icarium]

He didn't abuse them, he just unlocked a hidden feature...

Mikhail was very good at that. Like how he unlocked the hidden feature of my maestro chassis, i.e. to hold wall warts.

Kid blowing the whistle in mario 3 in the movie "The Wizard" had nothing on him.

Mikhail with a power glove = game over bro.