[JoshK]

I also got some brass machine screws at the orange box, about the same price you mention.  Just wondered if there were other sources that were better.  Guess not.

I used the self etching primer on the motor runs too, as they are aluminum as well. 

[jrebman]

Josh,

I just came across this site the other day and thought you might be interested (if you don't already know about it):

http://www.patina.com/

I'm planning on a faux, hammered copper finish on the hammond steel chassis as I think it will nicely complement the birdseye Jatoba end panels.  I'm also going to fashion a copper bottom plate from that big .125" thick piece I have.

Here's the current status report:

I have all the major components -- all transformers, motor runs, and blank PCB all layed out on the chassis so I can start making the measurements for the machine shop.  The chassis is only 2" deep (which I purposely chose), and that has forced me to make a few changes:  the PS choke had to be sent back to Jack to put endbells on it as it will no longer fit underneath, the 40 uF 630v film cap for the first PS cap has to be built up of two 22 uF 630 v caps instead, and it look as if it's going to be too tight for the film type cathode bypasses, so I have a selection of BG N and NXs and some silmics  to choose from there.  This is a compromise I really didn't want to make, but it's also one I won't lose any sleep over.  The layout is fairly compact, but there is still plenty of room for good seperation of the PT and OPTs, and the remainder of the PS components can also be placed for optimum wire runs.

I also found out that I have a decent amount of Mogami 2799 shielded, star-quad mini mic cable to wire the inputs with, so that should help with keeping things quiet.

When you get a chance, can you describe how the volume pot should be hooked up?  I have a 50k and 100k PEC pot, and while I know how to wire a standard volume control, it seems that there may be a better way to do it.  Not sure what George recommends, but if it would work to wire it into the grid-leak positions on the PCB, that mght be a better option -- just not sure how exactly to do that and if it necessitates tweaking the grid stopper, or if that's even needed anymore.  I've looked online but can't find a description of how this is done.

Anybody know if Hammerite paint is still available?

Thanks,

Jim

[DaveC113]

The amp lives!

I wired it last night, built the powercord and re-checked the wiring this morning, then fired it up connected to a cheap pair of JBL bookshelf speakers. I operated it in triode and ul for a couple hours, then connected it up to my Omega XRS, in UL mode with no CFB. I didn't need to worry about liking this amp more than my modified Trends T-amp I was using, its in another league entirely. I'm sure as it burns in it will improve a good bit too. Unfortunately, the shelf I was going to put it on isn't deep enough, so I need to figure out some sort of improved rack/shelf system. Right now its running backwards with the IEC and speaker jacks facing forward...

Hopefully I will get to compare it to another SimpleSE without a preamp and running the 12at7 driver tube soon as well. I am using a new ccs-loaded JJ ecc99 driver, and an Anthem Pre1 preamp. I am also using new Tung Sol 6550 power tubes, and a Sovtek rectifier, at least until my NOS GE 5ar4 gets here. I'll try to get some pics after I figure out some better rack/shelf system.

So far, this amp really makes the imaging shine. Parts of the music that the Trends smeared together are now resolved in great detail, so the instruments and vocals are more distinct. The soundstage is more convincing, the speakers just disappear into the music. Tone is also very clean and accurate sounding, vocals and acoustic instruments sound just right.

Also, the Omega XRS have really shown that they are a very accurate and clear speaker, and are fully worthy of the best gear you can possibly put behind them. They are not going to be a limiting factor in your system regardless of how much money you have available to spend, with the possible exception of providing sound for a large space.     

[DaveC113]

A couple pics of the finished amp:

[JoshK]

Congratulations it looks fantastic!   What finish did you use on the top plate?  Can't remember if I asked already.

I am jealous that you are able to listen to yours.   I had to spend the day working on installing a door to our one and only working bathroom as I have guests coming to stay tomorrow.   

I can't wait to fire mine up.  I've been itching to wire it up even before I finish the chassis just to hear it, but I don't want to have to take it down again, so I'll wait.

[DaveC113]

The paint is Rust-Oleum brown hammered finish, I used the clean metal primer too. I just sanded the alum right before using the primer and got ok results. The primer is a lot stronger than the paint, but the topcoat is pretty soft, even after curing for a week or so. I tried hard not to bump the topsheet with the screwdriver.

I had a little bit of ground hum, but strapping the chassis of the preamp with the amp w/ a 12g wire solved the issue, moving the amp to a seperate circuit in the house didn't even help much. Overall, its pretty quiet, theres a little bit of residual ground hum and some hiss at full volume, but its not audible more than a few inches from the speaker, which is good enough for me.

The final touch will be the NOS GE branded Mullard 5ar4 I have on the way, the JJ 5ar4 tubes are a little scary, one arced in another local guy's amp causing minor damage, and one was responsible for some damage to my preamp recently too. I've got a Sovtek for now, maybe the best option for a new tube? I'm not sure there are any good new production options... this is certainly a weak point, because the NOS 5ar4s are selling for a lot of cash, and the pricing is only going up. 

[jrebman]

Dave,

Congrats!  Can't wait to hear it, and one day this summer we'll have to compare it with the Sig 30.2 and Carina.

Josh, no comment on the site I pointed you to?

All, there is what appears to be a better option for a current production 5AR4, just that right now it looks as if it can only be ordered directly from The Amplifier Doctor in Germany -- this would be the TAD 5AR4/GZ34.  A lot of folks seem to really like these, they are built like the rest of the TAD tubes -- like tanks as they are designed for abuse in guitar amps primarily, but there are no North American distributiors that I've been able to locate so far.

The biggest issue with the Soveteks, aside from their normal, slightly harsh presentation, is that they generally last only a year before they die, and people have found out that if you don't replace them fairly regularly you end up with the same sort of failures as has been seen recently with some of the JJs.  The economics are still more favorable for the NOS types because a $120 Mullard that will last 25-50 years is still cheaper in the long run to buying 25 or 50 JJs or Sovteks at (current) prices of $12 - $18 each.  At least that's the way I see it.

Now, if we could convince one of the more reliable tube vendors here to start carrying the TADs., that would be my choice for new production.  Let's just say that most of my experiences with Sovteks have left me pretty disappointed.

-- Jim

[DaveC113]

Thanks Jim, I'd be willing to try the TAD if we can get a group buy or have a TAD dealer import them. When Mike checked, shipping (and the value of the dollar) was going to make them a little too expensive so I opted to look for NOS / used Mullards. I was also worried that the TADs are just a re-labeled current production Chinese or Russian tube, like the Groove Tubes (Sovtek) I paid $20 for  Last year about this time the Sylvania big bottles were going for about $50-$60, now they're more like $80... If I had a bunch of money, investing in lots of NOS 5ar4 tubes seems like a good investment.

Some day soon we'll have to have a get together and listen to some amps... we just need a host with the right space, my living room could only hold 2 or 3 people at a time.

Dave

[JoshK]

Hey Jim,

Thanks for the link.  I haven't seen it before and hadn't yet took a look at it. 

[jrebman]

Dave,

We just got a new sectional couch so we have a bit better seating capacity now, so we can probably do something here a little later in the summer.  I should have my Carina by then, my Horns should be finished and well on the way to being broken in, and my custom F120A fonkens should also be here, so there will be plenty of good SET/Single-driver stuff to listen to and mix and match.

I wrote to the folks at Thetubestore.com this morning to see if they'd be willing to bring in the TAD tubes -- we'll see.  They are also definitely not relabelled -- TAD designed the tubes, and has them built to their specs.  The EL84s feel like you could run a truck over them, and the guitar amp guys say lots of great things about all of their tubes -- both sonics and construction.

Josh, if you follow up with that place, do let us know what you find.

-- Jim

[nodiak]

Dave, congrats! Looks very nice! Will keep up on your impressions, and will be great if you and Jim do a comparison. The pictures are especially helpful to me as a first time builder and are much appreciated.
My layout has the Allied pt, 2 motor runs and pcb/tubes in same positions as yours, but then the opt's are in back of pcb/tubes. Spraying the alum top plate with hammer tone also, and curly burled, rotted, diseased maple chassis.
I'd go in on a TAD 5AR4 buy if it happens, may also see about a Mullard somewhere. I only have Sovteks now which have been fine so far but less than a few hundred hours on them.
Don

[JoshK]

I don't use standard tube rectumfryers in my gear, I use damper diodes, but couldn't you use a 5R4 instead of the 5AR4?  It is a beefier rect'r, but it is directly heated so needed to be wired different. The 5R4 seems not so hard to come by and not as expensive.

[nodiak]

diyaudio thread on slow start rectifier, 5AR4 burning, and damper diodes mentioned:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=125628

[jrebman]

Well, Dave gets the bonus prize regarding the TAD rectifiers -- they are indeed relabeled Shuguang tubes, but they are a heavy duty type with a brown base and you can find essentially the same thing from a number of vendors with a black base and the shuguang label.  Still, as the reports from those who have used the TAD branded shuguangs are still overwhelmingly positive, I'm not going to subtract any points for relabeling.  Which is to say that I plan to order a couple and give them a try for myself.

I'll have more details tomorrow, but TAD does indeed design their own tubes that are produced in China exclusively for them -- the EL84 STR, 6V6, and a couple flavors of the 6L6 fall into this category.  Others like the various flavors of EL34s and the rectifiers I just mentioned are relabelled units from other manufacturers (and not just shuguang).

If folks are interested I can list a few of these... tomorrow.

No progress on the SimpleSE today and no sign of my titanium drill bit set, but at least today I did manage to get my very noisy Infrant server relocated to a quiet, well ventilated place (which was mostly a matter of running a CAT-5 network cable), which was enough work on my first anniversary.

-- Jim

[nodiak]

Small surge of accomplishment today - got the top plate drilled out, felt good! A few more parts to order, will do asap. Will just keep doing things in fits and starts until it's done.
Don

[Dmason]

FWIW, I can strongly recommend against the JJ GZ34, having arc'd thru 3 of them, they all have a built in meltdown protocol at around the 60 hour point. The third one did some damage. There is also a growing respect for the Weber Copper sleeve solid state rectifiers, dont know the link, but they seem to have dialed in that particular design. The NOS GZ34 is ramping up fast, in price unfortunately.

Dave, that is one SICK looking machine. Love it.

[DaveC113]

...and curly burled, rotted, diseased maple chassis.

Hey, thats spalted... it makes it looks better if you call it that  It will be nice to see it, figured maple is one of my favorites. Its hard to find the time to work on it, but I think after you've spent a good chunk of change on a pile of parts you get motivated... I bought most of the parts around last xmas.

I got the Mullard 5ar4, its a '62 vintage, used but tested perfect. I also picked up a mystery RCA 5ar4 on agon for $20. It ended up being a 70's Sylvania Big Bottle, looks perfect, and works great in my preamp. The only place I found them for sale was tubeworld for $150, probably NOS instead of used though...The prices are high, I bet it will only take one decent new production tube for the market to go back down. In the meantime, they are still a good value compared to new tubes

Also, I'd like to hear opinions of using a thermistor for inrush current limiting. George recommended one on diyaudio recently, but I wonder if it could have a negative sonic effect. I was thinking you'd put it on the incoming ac line before the fuse. If its not really necessary for my tubes and caps longevity, then I see no reason to use it, and would rather avoid it if possible. Another option could be a series resistor on a timed relay, possibly better than a thermistor?

Dan, thanks for the compliment. I'm thinking a matching preamp would be nice too, but matching might be pretty much impossible. Maybe the same chassis design, but contrasting wood... 

[Len_Dreyer]

Antique Electronic Supply appears to have the TAD 5AR4/GZ34 for $19.00. Just search on TAD.

http://www.tubesandmore.com/

[jrebman]

Len,

Thanks for that -- for some reason I never saw that show up on my google search, but then AES's web site is pretty antiquated technology anyway.

One word of caution -- anybody considering getting the EL84s from AES -- these are not the premium STR types so look for a genuine EL84 STR.

Does anybody have a digikey part number for a power entry module -- one that has an IEC connector, fuse, and switch, and can mount with a single hole -- i.e. - don't have to machine out a square hole for snap-in mounting.

They have zillions of power entry modules and this is one of those places where one picture is worth ten thousand words.

Thanks,

Jim

[jeffdavison]

I like Cocoms. The one I use has a filter built in as well. I use Toroids and the more filtering the better.

Corcom # 5EHM1S   Mouser #592-5EHM1S

Lists for around $30 bucks or so.

http://www.mouser.com/Search/ProductDetail.aspx?qs=kHSGSskTvQNDT6gTPwjk%2fA%3d%3d

Jeff

Does anybody have a digikey part number for a power entry module -- one that has an IEC connector, fuse, and switch, and can mount with a single hole -- i.e. - don't have to machine out a square hole for snap-in mounting.

They have zillions of power entry modules and this is one of those places where one picture is worth ten thousand words.

Thanks,

Jim