Gibson EH-185

[pompeiisneaks]

I've got a first draft at a schematic in easysch for the gibson eh-185.  I'm interested in the amp because one of my favorite guitarists, Joshua Homme used it when he played in Them Crooked Vultures. 

I noted the common pictures of this amp show it with a treble and bass control, and saw two versions on the schematics page here:

http://el34world.com/charts/Schematics/files/gibson/Gibson_EH-185_65Q7_PRE.pdf

which seems very much like a clone of the EH-150, but doesn't have a bass tone stack element.  Then there is:

http://el34world.com/charts/Schematics/files/gibson/Gibson_EH-185_6J7_PRE.pdf

which does have it, and seems a bit more complex all in all.  I was considering basing it off the second, but found that the tubes (6J7) require the anode connector, and don't know how feasible that is to build nowadays...  So I kept my schematic based on the earlier one.  (If I'm off base on that assumption, please do comment).

I also may end up building this amp as my next build (some day in the future), but am first just trying to sort it out logically.  I have a few questions in general about the schematic, as its a bit 'empty' of some data:

1. There is no listed output transformer.  Is there a pretty common output transformer for 2 6L6's?   Or do you need to fit an OT based upon the entire preamp and power amp stages impedance? 
2. There's a named PT, but it seems hard to find, the one I did was pretty pricy, 200$ or so here: http://www.mercurymagnetics.com/pages/catalog/manufacturers/MM_gibson.htm which specifies it is for a EH-150 and there's a separate one for the EH-185.  Could I just use a modern one that can push the right power to the 6L6's and the other tubes? 6SQ7/6N7?  I can look that up on the data sheet, and get the total amp required for hte tubes, and see the levels there, that's what you do right? Then I look at normal voltages for these tubes and can look at the expected voltages?  (since they're also not noted anywhere on the original schematic?)
3. Could I just add the same bass controls from the second one into the first and get the same effect?  Or is the latter schematic above just the more modern version and will likely have a massively different tone than the second type EH-185?

At any rate, here's the .sch as well.  Let me know what you see is off/wrong, etc.

Edit: With latest layout and schematic.

Edit: Adding the latest mods as well.

[pompeiisneaks]

So trying to do the math, someone can double check me ;)  I am guessing a typical fender PT and OT may work here with the 2 6L6's in the amp.  From the tubes I get:

3x 6SQ7
Heaters: 0.3A @ 6.3V
Main: 1.1mA

1x 6N7
Heaters: 0.8A @ 6.3V
Main: 7mA

2x 6L6
Heaters: 0.9A @ 6.3V
Main: 145mA

So heaters need:

0.9 + 0.8 + 1.8 = 35mA

and main needs:

3.3 + 7 +  290 = 300.3 mA 

If I read the max amps right on the datasheets for each that is.     

It seems then that this transformer:

http://www.mojotone.com/transformers/Fender/Power/MT-FENDER-MOJO763.pdf

should have excess to cover that need.  Does that look right?  Is there something better?   I see Doug has the one just below it, the 762, but that seems short on current for the amps main power. 

Then for output transformer, I see the 6L6 seems to be 6600 ohms per, so 13200 ohms for the OT does that mean that the only ones I see on Dougs page that could cover that and be in the ballpark is the part 022921 that has 14,500 primary?

Or do you treat the 6000 ohms in this case in parallel resistance due to the push-pull and it only needs 3000 ohms?    If its 3k it seems that none that Doug carries are 3k, a few 4 and 5k, is 1k impedance mismatch a big deal?  I would guess a 1k difference on that kind of winding would be what 3k to 4 ohm 750 winding ratio, then for 4k that ends up as 5.3 ohms... not sure if that's significant?

Or am I missing how you determine the OT?

I've done a lot of reading on this stuff but lost the links and keep looking and getting bupkis...

~Phil

[shooter]

0.9 + 0.8 + 1.8 = 35mA

double-check, I think your decimal slipped

[sluckey]

2x 6L6
Heaters: 0.9A @ 6.3V
Main: 145mA

When you say "Main" what are you referring to?

The Mojo763 is made for a 4 x 6L6 amp such as a Twin Reverb. Way too big for your needs.

The Mojo762 is made for a 2 x 6L6 amp such as Bassman or Super Reverb. Perfect for your needs.

Doug's 018343 OT is perfect for your needs.

[Willabe]

The Mojo762 is made for a 2 x 6L6 amp such as Bassman or Super Reverb. Perfect for your needs.

Doug's 018343 OT is perfect for your needs.

And if you still want the Mojo762, Doug can get that for you from them at Mojo's quantity discount, even when you buy only 1.     

[sluckey]

Here's a little tidbit about schematics from the '50s... Many schematics used "M" to mean 1000 just like the Roman Numeral "M". IOW, a resistor value labeled as 100M is not 100 million. It is 100 thousand. When referring to million they would use "Meg". IOW, 1 Meg is 1 million ohms.

Sometime later it became more standardized, with K = kilo = 1,000 and M = mega = 1,000,000.

So, you may want to fix that on your schematic. While you're in edit mode change the value of R1 to 2M (that's million). And add a 100K plate resistor for V2 and V3.

[kagliostro]

If of interest, here a pair of layout for the version that uses the tubes with topcap





the souce is AX84, this thread (I think the layout are to be revised)

http://ax84.com/bbs/dm.php?thread=457349

Franco

[pompeiisneaks]

0.9 + 0.8 + 1.8 = 35mA

double-check, I think your decimal slipped

Lol it didn't slip it fell right out, thanks 3.5 ;)

~Phil

[pompeiisneaks]

2x 6L6
Heaters: 0.9A @ 6.3V
Main: 145mA

When you say "Main" what are you referring to?

The Mojo763 is made for a 4 x 6L6 amp such as a Twin Reverb. Way too big for your needs.

The Mojo762 is made for a 2 x 6L6 amp such as Bassman or Super Reverb. Perfect for your needs.

Doug's 018343 OT is perfect for your needs.

I meant the combination of the anode current and screen current max values per the datasheet.  (that's where I got 145, anode is 130 and screen is 14.)  Is there a correct term for that or are they called out separately and then added after?

The reason I thought the mojo 753 was needed is because the calculations of current are 300mA and the 752 only lists 250mA.  Is it okay to be over current on the transformer design? 

~Phil

[pompeiisneaks]

Okay, here's the modified version per your comments sluckey.  I figured that M seemed really wrong, but I just reproduced it as it came :)  That's a great thing to know about the M vs Meg in those old ones. 

I also had another question I forgot to ask.  I don't think getting a field coil speaker is feasible or worth it nowadays, so I replaced it with a 5H choke, that seemed to me to be common for the 6L6 Push Pull amps, but is there something that can help me decide on a valid choke there. 

Per kagliostro's images, it makes me wonder if I should do the newer schematic with the bass and using the top connected tubes.  How hard are those to do nowadays?  I know the NOS tubes are out there in pretty decent supply, I'm more curious as to how I'll find the tops and how you wire those normally.   

Or should I just stick to the older schematic I'm looking at now?

I'm up for the challenge either way, I just don't want to build something that is going to be me manufacturing the parts due to not having them around.

Thanks for all the help.

Edit: remove old schematic. Latest and greatest is in first post.

~Phil

[kagliostro]

Unfortunately this kind of ceramic topcap is easy to be find



but this is good (very good) for topcap plates connections

on the 6J7 tubes on the top there is a grid connection and the cap we really need is this metal topcap shield





that is very difficult to be found (even if not impossible to build, perhaps using one ceramic and a little metal sheet or pipe)

Franco

[HotBluePlates]

I noted the common pictures of this amp show it with a treble and bass control, and saw two versions on the schematics page here:

http://el34world.com/charts/Schematics/files/gibson/Gibson_EH-185_65Q7_PRE.pdf

which seems very much like a clone of the EH-150, but doesn't have a bass tone stack element.  Then there is:

http://el34world.com/charts/Schematics/files/gibson/Gibson_EH-185_6J7_PRE.pdf

which does have it, and seems a bit more complex all in all.  I was considering basing it off the second, but found that the tubes (6J7) require the anode connector, and don't know how feasible that is to build nowadays...  So I kept my schematic based on the earlier one.  ...

They're actually pretty-different amps in terms of preamp gain.

The 6J7 you're concerned about has a later equivalent: 6SJ7. The "S" means "single-ended" but not in the way you're used to seeing. It means essentially "a 6J7 but with the top cap moved to a base pin". In other words, all connections come out of a "single end" of the tube. So you could just use the 6SJ7 in the schematic for 6J7, and wire as typical for an octal socket.

Catch is, the 6J7/6SJ7 is a pentode, but each are wired as triodes in the schematic we have. And the amplification factor of a 6J7/6SJ7 is 20, on par with a 12AU7 section.

The 6SQ7 is like half a 12AX7 with a couple of diodes (not used here). Circuit values are kept the same in this schematic, but each triode will have an amplification factor of 100 instead of the 20 for the 6J7's.

I would assume one will sound gainier than the other on the mic channel, less so on the instrument channel (because the lower gain 6J7 triode version cascades 2 stages instead of using 1 before the phase inverter, as in the 6SQ7 version).

It would be nice to know which version your icon used...

[DummyLoad]

just as a point of interest: 6J7 and 6SJ7 are different enough to have their own R-C charts. they are similar but not same.

6J7 uses chart 14, 6SJ7 uses chart 20. 6J7 has about 3/4 gm of the 6SJ7. 

see pages 255 and 258 in the link below:
http://www.americanradiohistory.com/Archive-Catalogs/RCA/RCA-Recieving-Tubes-1950.pdf

from experience in experimenting with both tubes, i prefer the 6J7: to me it's smoother sounding overall.

--pete

[pompeiisneaks]

Yeah, that's the tricky part, I've only seen photos from the front, so I'm not sure which HBP.  I think the only days I have is that he uses both an eh-150 from 1939, and an eh-185 from 1938, not sure when they started the second revision of the eh-185. 

kagliostro, are you saying the metal call is required to do something akin to shielding it?  Maybe I can build the 6j7 version with the 6sj7 like HBP mentioned?

Thanks all!

[pompeiisneaks]

just as a point of interest: 6J7 and 6SJ7 are different enough to have their own R-C charts. they are similar but not same.

6J7 uses chart 14, 6SJ7 uses chart 20. 6J7 has about 3/4 gm of the 6SJ7. 

see pages 255 and 258 in the link below:
http://www.americanradiohistory.com/Archive-Catalogs/RCA/RCA-Recieving-Tubes-1950.pdf

from experience in experimenting with both tubes, i prefer the 6J7: to me it's smoother sounding overall.

--pete

ahh dang, then if I do that, I'd likely want to stick with the 6J7.  So if I go that route instead, I'm guessing that I need to find some way of manufacturing those top caps.  Are they for shielding?  It looks like there is a metal dome with some kind of inner rubberized or plastic section to not short out the actual post when over it?  Any ideas?   If not, I'll stick to the original eh-150-like version

[mresistor]

http://www.ebay.com/sch/i.html?_nkw=vacuum+tube+plate+caps

[pompeiisneaks]

http://www.ebay.com/sch/i.html?_nkw=vacuum+tube+plate+caps

Cool, thanks.  But don't I also need the metal top part that was shown by kagliostro?  Or do those ceramic tops work okay? Sorry I'm confused because if I understood what he mentioned, you need a different kind for the 6J7. 

Also, what kind of wire do you use?  Just standard wire or is it some kind of shielded cable?

Anyone have any input on the question about the choke?
 
:)

Thanks.

~Phil

[kagliostro]

My opinion is that is preferable to use those small metal shields for the topcap of tubes where the topcap is a grid connection

may be is possible to do without, but is something to be tried same for the grid connection a shielded cable is preferable but ....

To build by themselves those small topcaps shields is surely possible, what is to be discovered is the way to do it with the minimum effort

may be the use of a ceramic or plastic topcap in junction with a piece of aluminium pipe


As suggested, also a version with 6SJ7 tubes can be build, I think it will be in the middle between the 6SQ7 and the 6J7 versions

Franco

[pompeiisneaks]

Thanks.

So I think I have just 2 remaining questions on this build that may have been missed. 

1. For the field coil speaker, is my 5H choke an adequate replacement?  It seems most chokes are 30 to 100 ohms only, but I don't know that a 750 ohm resistor there really matters much, as much as having something for the filtering of the power.  Is there some document that helps understand choke selection?  I did a lot of digging before I posted here and didn't find much.

2. I asked a question a few back also about the PT.  The one I mentioned had up to I think 350mA or 400mA and the circuit design seems to require a little over 300mA but I was told I could use the one that ends in 762 from mojotone.  That one only provides 250mA  Is that adequate?  If I recall from the data, the 6SQ7's tend to use a decent amount of current, thus pushing it over the 250mA that another typical 12AX7 type may not need.  I don't know enough about power transformer selection, but I thought you needed to calculate what all the tubes will draw and ensure you have enough?

Edit: I noted that mojotone 762 model supports a 5v tap for the tube rect. so removing that part of the above statement.

~Phil

[pompeiisneaks]

I'm just realizing that I'm def confused and potentially wrong on the current requirements for the 6L6's because I have listed 145 mA for those, that's what's putting it near the 300mA level.  So if the 250mA PT's are good for a 6L6 maybe I'm just off on that...

DOH, I just reread the datasheet, the value is 145 (or on the RCA one I've got) 152 max mA.  FOR BOTH TUBES!  It looks like that resolves my question, the 762 tranny would work just fine.

So if anyone has any pointers on the choke?   Do I add that one I have and add additional resistance to equal total of 750 ohms  (Say the choke I have is a 5o ohm choke, do I get a roughly 700 ohm resistor and place it in series there between caps?)

~Phil

[DummyLoad]

So if anyone has any pointers on the choke?   Do I add that one I have and add additional resistance to equal total of 750 ohms  (Say the choke I have is a 5o ohm choke, do I get a roughly 700 ohm resistor and place it in series there between caps?)

only IF you were to use a power transformer with the same specifications as the gibson. on larger amps in those days usually they were around 750VCT to compensate for the field coil and vacuum rectifier losses. the 752 transformer will put the B+ at about 450V with a SSR or 5AR4 and about 425V with a 5U4GB depending on idle load.

do you have any idea what the B+ was on the original EH185? you really should try find out. i'm betting it was around 380-400V in which case the 752 supplied B+ voltage would be out of line with the original design. do you even care? since it is a modern spin of a vintage design.

the sag is part of the tone IF the amp had a field coil. the best way to emulate that would be with a PT with similar ratings of the original and the field coil replaced with a 750 ohm 25W resistor. 

--pete

[pompeiisneaks]

DummyLoad,

Thanks,

I don't know the original B+ voltages, and I can't seem to find anything documenting it.  There is a replacement transformer done by Mercury Magnetics, but I can't seem to see any datasheet/specs for it (maybe they want to keep the sauce secret?).   

The rectifier in the schematic is a 5U4. 

As for sag, doesn't the rectifier give a decent amount of sag too?  I could definitely add a 25W 750 inline with the choke to provide that sag AND provide better power filtering?   

Not sure about doing a modern spin per se, just trying to get as close to the tone as possible with the available hardware we have now.

[DummyLoad]

I don't know the original B+ voltages, and I can't seem to find anything documenting it.  There is a replacement transformer done by Mercury Magnetics, but I can't seem to see any datasheet/specs for it (maybe they want to keep the sauce secret?).   The rectifier in the schematic is a 5U4.  As for sag, doesn't the rectifier give a decent amount of sag too?  I could definitely add a 25W 750 inline with the choke to provide that sag AND provide better power filtering?

then the MM PT & OT would be the place to start. NOS 6L6G, 5U4G, 6J7, etc.. add the 750R power resistor to emulate the missing field coil.

strapped for cash? - ask MM for the specs and find close match off the shelf.

--pete

[pompeiisneaks]

yeah I wouldn't say I'm 'strapped for cash' but always under a budget on my pasttimes ;).  Gotta get clearance with the better half.  It may be a hard sell for trannies that cost 140$ and 212$ when I can get the fender style ones for 80 to 100 each.  I'm just on the fence about 'exact' vs 'modern' like you said as well... I'll decide on it and go from there.

Thanks!

~Phil

[PRR]

> current max values per the datasheet.

Tube-maker's datasheet is just a suggestion.

You have ALL the data you need to figure what *Gibson* was working it at.

You know there is 106V drop in a 750 Ohm resistor (field) which carries all the current.

You see there is 275V dropped across a 20K bleeder.

Very little math tells you there is 141mA total, 14mA to bleeder, must-be 127mA to amplifier.

(Of course if we keep going, we find 20V across 200r cathode resistor, 100mA P+S in 6L6es, so 27mA to small-tubes, but none of them can possibly suck even 2.75mA because of 100,000r resistors.... take with pinch of salt.)

Knowing the first-cap has 275V+106V= 381V, and about 141mA total, we turn to 5U4 data and find that point. Lies very near the "350Vrms" line.

So 350V AC each side (700V CT).

Why that bleeder? If the 5U4 comes-up before the 6L6, the first cap rises to 350V*1.414= 495V. Which is more than a 450V cap should take steady. It may be fine for a few-second start-up a few times a week, or maybe not. The added 25mA (at 495V) load may hold the peak start surge to 460V, 470V, but something short of 495V. It will also bleed-down to less-fatal voltage in several seconds even if the 6L6es are missing.

The real reason for the 20K may be to up the field coil current.

The power amp: Whether we take the 100mA implied at cathode resistor or the 122mA implied by power supply study, this amp is working at lower current than any of the 6L6 270V conditions I see. I wonder if it is 6K or 8K load, or if Gibson idles it cool and lets it strain at full power at 5K load. In any case it seems to run nearer 14W-18W than the 25W-30W that a self-bias pair of 6L6 can do with more voltage.

The sub-par power rating is roughly confirmed by the field coil demand. IME, field coil power is similar to undistorted sine audio power. (There's no law, but that seems to have been a commercially economical condition.) As FC power is 106V*141mA= 15 Watts, we would suspect audio output in the 15W zone.

[kagliostro]

PRR has given us a detailed explanation  (Thanks PRR)

on this page you can find a short explanation about the substitution of a field coil

with an inductor + an in series resistor as to build a fake Field Coil Box (useful for radio repairers)

http://plymouthcolony.net/starcity/radios/pages/unispkr.html

Franco

[sluckey]

Your revised schematic is still wrong. V2 and V3 plates should be tied together with a single 100K connected to the junction of R17 and C8. And the junction of R17 and C8 should NOT be connected to ground.

I'd just replace the field coil with a 750Ω or 1K resistor rated for 50W.

[DummyLoad]

Your revised schematic is still wrong. V2 and V3 plates should be tied together with a single 100K connected to the junction of R17 and C8. And the junction of R17 and C8 should NOT be connected to ground.

I'd just replace the field coil with a 750Ω or 1K resistor rated for 50W.

this should do it.

R7 is removed.

--pete

[DummyLoad]

6J7 pre version - redrawn with modern component values, eliminated the field coil, and a smattering more legible.


--pete

[pompeiisneaks]

Thanks to all!  I'll give this a closer look after work.  Excellent information that's going to take a few reads to digest :)

Phil

[pompeiisneaks]

You know PRR, sometimes I feel like slapping myself when I realize that one of the two schematics I had/showed included voltages (I looked up the tubes first and once I saw that it had tubes with the grid connector on top, I was scared away :D.  I never looked at it in close detail enough to see the voltages.  (and the transformer ID is the same.)

All the math now adds up. 

The other good news is that means the mojotone 762 is a match, its 354-0-354 and has the current to handle it all.  Seems like I wouldn't need the 'original' transformer.

Is there any data to back up the idea that the transformers (either or both) have a major impact on tone of the amp?  Or is that more related to the tubes, tube biasing and overall design of the entire circuit? 

I think some of that question, sadly, is opinion, but I'm now thinking that to get the 'right' tone I likely wouldn't need the original exact style transformer anyway.  (I'm trying to justify logically, in my head, why I would go for the extra couple hundred bucks for the MM ones?)

Thanks to all, this really fleshes out the last details. 

DummyLoad, I'll take a look at the schematics once I get home, I don't have a schematic viewer on my work mac :)

~Phil

[kagliostro]

If you can load on your work Mac the program (I'm not sure you have permission), here you find the program also in Mac version

http://dhost.info/jschem/

Franco

[pompeiisneaks]

I can install it, but I tried running it and it apparently wants verison 1.6 of java which is 2 generations old and not considered secure (I'm a java developer :)) so for now I'll wait.  I talked with the guy that created that app about getting it up to date and he set me up with the code in github but I've not had time to go back and get it working in java 1.8, but he may have, maybe I need to look that up again.

~Phil

[pompeiisneaks]

DummyLoad, looking at your 6J7 schematic, is there a reason that you put in KT88's instead of the 6L6's I've seen in the schematics that  were there?  Are they nearly identical to the characteristics of the 6L6?  Or does it give it a different overall tonal characteristic?

~Phil

[DummyLoad]

DummyLoad, looking at your 6J7 schematic, is there a reason that you put in KT88's instead of the 6L6's I've seen in the schematics that  were there?  Are they nearly identical to the characteristics of the 6L6?  Or does it give it a different overall tonal characteristic?

~Phil

it's a symbol. change the name. i use it for 6V6, 6L6, kt88, etc.. it was late, i was tired, etc..


rev1a files attached.


--pete

[kagliostro]

Pete do you use PC Express to draw the schematics ?

---

Someone has info about the correct inductor to be used for the bass control ?

On the layout I've previously posted there is a 20H 1850R inductor but I'm not sure if that is a correct value

Franco

[DummyLoad]

Pete do you use PC Express to draw the schematics ?

---

Someone has info about the correct inductor to be used for the bass control ?

On the layout I've previously posted there is a 20H 1850R inductor but I'm not sure if that is a correct value

Franco

yes. expressSCH. for now. i am looking at design spark. kicad was just too quirky: maybe it's better now, but i doubt i'd warm up to it.


--pete

[kagliostro]

Give a try to this

http://darwinne.github.io/FidoCadJ/index.html


(tube library on the program - easy to draw new components - I've some tubes to be added)

Franco

p.s.: If someone knows something about the Bass tone control inductor, welcome

[pompeiisneaks]

DummyLoad, looking at your 6J7 schematic, is there a reason that you put in KT88's instead of the 6L6's I've seen in the schematics that  were there?  Are they nearly identical to the characteristics of the 6L6?  Or does it give it a different overall tonal characteristic?

~Phil

it's a symbol. change the name. i use it for 6V6, 6L6, kt88, etc.. it was late, i was tired, etc..


rev1a files attached.


--pete

Thanks, and no worries, I'm so new I just wanted to make sure I understood it. 

I ask a lot of questions, and I appreciate the answers!

~Phil

[PRR]

I think that tone control has major problems as valued.

The 500K pots hardly do anything until you get near the ends.

I empirically derived this variant.

As drawn here, the bottom of the pot is "more".

Oddly enough, the pots should be Linear.

Choke is 5H to 10H. I like ~~7H best. 2K DCR limits the boost, you want less. Going below 500 gains nothing. This IS a small SE OT primary. If you can find table-radio 5K 25mA, that may be a good start.

The 0.003u and 0.5u caps appear to shave the bottom octave of guitar. I have used full-bass values. If you use a small cheap tight speaker, or only play soprano, you may prefer the stock values.

[pompeiisneaks]

PRR,  Thanks I'll look into those mods, I'm thinking I'm going for the newer, less complex 6SQ7 version first, and they I may just try for the other with the choke for the bass controls. 

I've got a layout for the build now too.  Let me know if I'm missing anything obvious here. 

Edit:  latest layout and schematic in first post

[kagliostro]

Thanks for sharing the .vsd version of the layout   


Franco

[sluckey]

The ground connection for your volume control is on the wrong lug. As drawn, the pot will operate backwards.

Just a personal choice... I like to select all turrets, then right click and chose 'bring to front'. This keeps the cross hairs visible. I print and tape the board layout to the actual board for a drill guide and the cross hairs serve as an accurate location for center punching prior to drilling.

[pompeiisneaks]

Ahh yup, fixed and I did the turret trick.  It looks a lot nicer now too, thanks!

[pompeiisneaks]

For those curious, I'm starting to buy the parts to put this one together. 

I'm going to have to take it slow, I try to keep my builds under a budget, and the parts are going to cost enough to eat up about 3 months of budget :) I got the board, and most of the components this month (caps, resistors, tube sockets), I got the chassis last month after my Vox parts (Glad that one's working lol). 

Next month will be a transformer and some of the other sundries, and in May I'll finish off with the other transformer and tubes (they'll all be NOS so I don't want to buy them, find out they don't work and not be able to return them). 

As with the vox I'm going to do a video series on the build.  The videos were fun, hopefully for others as well heh. 

~Phil

[pompeiisneaks]

So I just was reviewing my layout and noted I'd missed the second volume pot for the guitar input heh.  Added.

Edit: latest schematic and layout are in the first post.

~Phil

[HommeMarrBuckley]

Not sure how I missed this thread.  I am very interested in how this turns out for you.  I am amazed how something this old can have such a bite. I am a big fan of the player as well-hence my user.  Maybe down the road you can try the Checkmate 25.  Ha.
I'll be watching.

[pompeiisneaks]

Thanks!  I also dig Johnny Marr a ton too :)

I've just updated the my layout, I got the first wave of the parts, and found I had put all of the caps as 0.01 when only the first was 0.01uF the other three are 0.1 uF.  Here's the updated version.  I don't know if I've tweaked the schematic much, but I'll attach that too as my 'latest'.

Edit: latest schematic and layout are in the first post.

~Phil

[pompeiisneaks]

Doing more review, (as I don't want to be caught like I did last time and miss something on the translation) and I found another error on the layout.  Attaching latest layout and schematic.

Edit: latest schematic and layout are in the first post.

~Phil

[sluckey]

I was wondering when you were gonna fix that. 

I had meant to mention that when I first saw it but got busy doing springtime stuff. So, I'll mention a couple other things I saw on your layout. You have 3 20 watt power resistors on the board, but you used a symbol that's sized for a 5 watt resistor. I don't know of any 20W that will fit in that space. But even if they would fit, I would not put a 20W resistor on the board. Those resistors need plenty of air space for cooling.

Those input jacks with the 100K resistors are wired wrong on your layout. As you have them either unused jack will short out the other jack. Compare your schematic to your layout. You'll see what I mean.

Visio Pro does a very nice looking schematic, much better than expressSCH. Why don't you give it a try. The shapes are under "Electrical Engineering".