New ReleaSSSes

[wicker]

When I saw yesterday this schematic I desided to redraw it - man, it was pain in my a**. I'm not sure if it's all right, I'm not really sure if first filter is ok, the second should be fine, also the reverb was drawn so tricky that I had to think a bit, here's the schematic made in Eagle PCB (.sch format) so you can edit it, its only preamp with no power supply (at this moment its not so important imho).

[grtamp]

I can't see the .sch file!!!

[10thTx]

Edited and repost again later in the thread.

[martin manning]

10thTx, nice work! Not sure how this should be organized as far as iterating the schematic to something that is more correct, and by that I mean that obvious errors are noted and corrected according to consensus opinion. It'd be best to have a keeper of an "official" version lest there be a proliferation of them... maybe you just volunteered? The first step is to get agreement that your version is an accurate transcription of the hand drawn schematic.

[10thTx]

It'd be best to have a keeper of an "official" version lest there be a proliferation of them... maybe you just volunteered? The first step is to get agreement that your version is an accurate transcription of the hand drawn schematic.

I will pass on being the keeper of the official version ........... etc.....

I'm not interested in building this amp.

My preference would be someone else who is interested in this amp pick it up from here.

A TAG member left me a PM pointing out numerous mistakes and needed corrections. Hopefully, he will chime in here on the thread.

Once an edit has been done, I will delete my drawing so there is not confusion.

Any volunteers to pick this up and take this over?

The free download to edit this is right here: http://www.expresspcb.com/expresspcbhtm ... ftware.htm

With respect, 10thtx

[wicker]

So let's start from reverb, I think that it look far more better shown below. Now I wonder about this yellow wire marked 1. That is definetly an error, maybe it should go from cathode ? Hm but the signal seems to be in faze then ...

[markusw]

Here's a couple of differences I found between the schematics posted by 10thTx and the "original" hand drawn schemo:

The 270R resistor in the tail of the PI is missing (it goes from the 18k/100n connection to gnd). The 2k7 NFB resistor should be in series with the NFB loop.

The 820R connected to the two 220k resistors and bias supply should be 820k.

The connection of the high filter pole to "green" is missing.
The connection of the low filter pole via a 270k to "green" is missing.

The 12BH7 drivers are reversed. Cathodes should go to the grids of the 6L6, anodes should be connected.

I don't have Express PCB installed and actually I do not want to install another software on my PC. So I won't be able to do the changes.

However, I'm almost done drawing the schem in LTSPice.
Still searching for a 12BH7 Spice model though that I can easily integrate.
If someone is interested I can provide you with the LTSpice file.
BTW, I checked the 100k volume pot in LTSpice. With 100k the Deep switch doesn't "work". With 1Meg it "works" like expected.

Regards,

Markus

[martin manning]

Markus, I'm interested in the LTSpice file... I though about doing one myself, and found a 12BH7, but it needs a little work to create a symbol, etc. I'm working on something else right now, but following along with interest, and will be glad to help where I can.

Anyone have a link to info or schematic of another amp with that type of power stage topology?

[10thTx]

Edited and schematic reposted on pg 8

[mobisimo]

Thank you for this amazing work. The preamp schematic resembles ODSR #13 quite a bit: http://ampgarage.com/forum/files/odreverb_902.pdf
Of course there is much more feedback here, along with the two tube mixer setup. One question: on V4a+b cathodes, usually the R/bypass C combination is elevated by 100R or 1k where feedback is used; why might we see the 100R resistors here but no local feedback (as we do on the reverb recovery stage of #13)?

[LeftyStrat]

Thanks for this 10thtx.

I'm trying to learn the ins and outs of jschem so I can work on these.

For those that have seen #004 drawings, how many tubes? The Ceriatone was based on #004, but I understand Nik dropped the cathode follower.

Looking at the pictures of the Ceriatone model, it has five noval tubes. It would have been six with the post-pi cf.

#002 has seven novals. Can I assume that #004 has a simplified reverb circuit?

[LeftyStrat]

#002 has seven novals. Can I assume that #004 has a simplified reverb circuit?

Never mind. I reread some of the posts and saw the comment about the DC coupled CF's not being in #004.

[boldaslove6789]

SSS #4 does not have a CF driver tube.

[10thTx]

I'm trying to learn the ins and outs of jschem so I can work on these.

That would be great! I'm not quite sure where to go from here. I know what my questions are, but I don't have the answers.

For those who are not familiar with jschem, it will work with a Mac & will open ExpressSCH files from what I understand.

Heinz, who participates on the Hoffman forum, developed jschem.

http://www.el34world.com/Forum/index.php?topic=763.0

With respect, 10thtx

[LeftyStrat]

Well, I don't have m4d 3l1te h4x0r sk1llz, but here's the best I can do.