[dude_500]

Does anyone have a good well-documented and tested phono preamp (preferably with tubes)? I can't find many that have any sort of guides just schematics in other languages.

Thanks

 

[nikongod]

bottlehead seduction.

 

[pabbi1]

Not tube, but how about the Pearl?

 

[breakfastchef]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif bottlehead seduction.

Oh, yes...x2. Stock "Seduction sounds great. There are several mods that can be done to make it even better (i.e. cap replacements, different tubes, more 'iron', etc.).

I believe Hagerman has a couple of tube phono pres, but you have to source some of the components.

 

[digger945]

Aikido phone preamp kit.

 

[Uncle Erik]

Check Bruce Rozenblit's Grounded Grid Phono at Transcendent Sound. You can buy a kit, you can buy it assembled or you can buy a copy of his "Audio Reality" book and get the schematics, parts list and writeup. The book also has a preamp and three power amp projects.

 

[dsavitsk]

Quote:

Originally Posted by dude_500 /img/forum/go_quote.gif Does anyone have a good well-documented and tested phono preamp (preferably with tubes)?

Here's mine: ecp.cc

Not quite a guide, but I can answer any questions you might have.

There are a few improvements you might make as well. In particular with a slightly more complicated PS and a servo that output cap can be eliminated. Also, the zener shunt reg can be replaced with a fancy glow tube.

Also, designing your own turns out to not be that difficult. Pick a tube with sufficient gain, plug some numbers into Hagtech's calculator, and you are almost done.

The Seduction has six major issues that would keep me away: The first is that the Z out is pretty high meaning that it can't drive difficult loads. The second is that the total gain is on the low side meaning that you'll need a preamp that can do some real work. The third is that is uses 6DJ8/6922's which is a dumb choice as there are better tubes for the purpose and 6dj8's have gotten too expensive. The fourth is that there are too many caps (including the power supply caps) in the signal path unless you add the C4S upgrade. The fifth is that it is really expensive for what it is, and finally, the sixth is that the whole naming scheme/nude modeling by the proprietor's wife is creepy.

 

[dude_500]

Can 6CG7 tubes be used? I have a whole box of those. If so I may try to build my own. I have not done that before, but it would be a fun project. I have built a Strain amp, just never made my own schematics.

 

[dsavitsk]

Quote:

Originally Posted by dude_500 /img/forum/go_quote.gif Can 6CG7 tubes be used? I have a whole box of those.

Only if you want to use the whole box. mu is low which would mean at least 3 gain stages (and maybe 4 depending on the cartridge and the rest of the system) plus a buffer (cathode follower). You can get tubes that are more appropriate for cheap -- 6GK5 (which are triode strapped pentodes b/t/w/) are $4 each in the quantities you need ($1 each if you buy 100) and are excellent tubes.

 

[dude_500]

I've been offered a NAD 1020 pre-amp for $80, is this a good price/machine? They say it's a legendary audiophile pre-amp, but it's from the 70's and very old. How would it compare with a DIY tube amp do you think?

 

[dude_500]

Quote:

Originally Posted by dsavitsk /img/forum/go_quote.gif Here's mine: ecp.cc Also, designing your own turns out to not be that difficult. Pick a tube with sufficient gain, plug some numbers into Hagtech's calculator, and you are almost done.

What's the best online literature for designing tube amps for someone who understands the fundamentals of electronics and building but not the mathematics or anything about tubes themselves?

 

[digger945]

I still own the NAD-1130 phono/pre, I used it for a HP amp for awhile and figured I'de save it for my first TT.
I've read many places that NAD is just a no frills Proton I believe.
I think I read somewhere that the 1020 is actually a 3020 without the "amp" guts.
I'm sure someone here is familiar with your particular unit.
Don't know how a SS pre will stack up against a tube pre. I'm sure they sound somewhat different.

 

[digger945]

My offerings are somewhat one-tracked because I have studied them and not much else, so...
Tubecad software.
Headwise projects library.
DIY audio projects.
DIY links and resources found right here in HF's DIY Big List and Rules Section.
Pete Millett's DIY Audio Pages.
diytube.com
Tube Cad Journal.
I'm sure the others have better websites than these.

 

[dsavitsk]

Quote:

Originally Posted by dude_500 /img/forum/go_quote.gif What's the best online literature for designing tube amps for someone who understands the fundamentals of electronics and building but not the mathematics or anything about tubes themselves?

Hmmm. You probably should pick up a copy of Morgan Jones, particularly if you have some electronics knowledge. The Navy's NEETS manual is good. Otherwise, there is a whole thread full of links at DIYAudio: diyAudio Forums - On Line Tube Learning for newbies.... - Page 1

 

[nikongod]

Quote:

Originally Posted by dsavitsk /img/forum/go_quote.gif Hmmm. You probably should pick up a copy of Morgan Jones, particularly if you have some electronics knowledge.

Second or third time this book (pair...) has come up... is it really worth owning these 2 books? There cant be ANYTHING worth learning from them... can there?

For the second or third time these have been recommended: They are well worth about $100 together for the 2. Maybe you can get them used for less.

To the OP: PLEASE Go buy them. Try not to think about building more stuff until you have read them.