Nos on the way. $700 worth.

[skyboltone]

I just placed an order for $700 worth of tubes from HI- Test guitars. Those of you who have never talked to Greg Levy are in for a treat if you've got money to spend. I think I got about 10 tubes for that price. But I intended to buy fewer and more expensive tubes. This guy provides tubes for the stars and he knows gain structure and all the amps through and through. Except Standel. He talked me out of English or Dutch tubes for the Fender Clone. When we talked about my HI-Watt plans he kinda just cringed. They just have to be Mullard power with Dutch front end. With the Iron I think it would be cheaper to buy an original 73 D-103 if it had Mullard outputs in it. HI-WATT is going to be an expensive proposition. I'm going to jump over to the HiWATT forum to find out what modern valves are being put in them.

To tell the truth I really don't remember exactly what I bought but I've had a set of Mercury Iron for a Black Face Deluxe Reverb for some time. He's going to make some notes about what goes where. I'm going to build it without the normal channel to save $125 bucks. So I bought all the tubes for that, and I got a set of Siemens EL34 and a set of Tung Sol 5881 both matched up at 450vdc on the plates. I think I'm going to put the TS 5881s in my Gibson GT-19RVT for now, with the Peerless OT subbed in and the Altec 417-8C. That's my current pedal steel amp. Sweet. At some point it's going to get a new PT with enough juice to drive the tubes/iron. I think I can get enough out of the old Jensen to pay for some of this.

I'm having fun. Ain't life grand!

Dan

[paulster]

Dan

He must be good if you've just spent $700, are sure you've got a bargain, and still don't know what you've actually purchased!

I've heard really good things about buying tubes from him, so I'll look forward to seeing exactly what you've got.

The old Mullard EL34s are a real problem these days, even for those of us in the UK where we (in theory) have a better chance of finding old stocks.

Believe me, I scour old electronic shops, TV repair shops and so on when I find them, and have managed to acquire some good NOS tubes, but trying to get matched quads is a bit of a challenge.

The Winged-C EL34s supposedly fare pretty well compared to Mullards for Marshalls, but you have to bias them really, really hot (80-85%) and therefore have no hint of parasitic oscillation, so I'd imagine they could work in the Hiwatt as well, at the expense of being eaten fairly quickly.

Paul

[BobW]

why not use NOS 6CA7s?

[skyboltone]

Hi Paul:
He does have the best rep I know of in the game. At least here an the US. He wants $345 a pair I think for xf2 with double getters. Can you imagine? And then abusing them to boot. I don't think so. Like Andy said a while ago, when these are gone it will create competition maybe to build better tubes. He really just doesn't like any NOS power tubes going in HIWatts but if somebody has to have them he'll do it.

He talked about balance across the amp from input to output. For instance: he says a Marshall is mid heavy and sucked out in the bass and treble. That's why the Mullard and Amperex sound so good on the front end. A Fender on the other hand is scooped in the mids and needs a lot of help in the bass. Hence the Tung sol. Very interesting. All about individual ears though. I hope I'm not going to have a different set of ears than him.

But like I said, he came recommended to me by a Nashville session guy that is in the Hall of Fame. This un-named player told me to follow his advice and they will last 50 years and be just the best from start to finish. The rest is in your hands. You know?

The odd thing was, that I was talking about the Fender Deluxe Reverb blackface and wanted to get the the RCA 6V6GTs and he said for the DR it's really not the right tube. It's ( according to him ) a tweed tube. He likes the Tung-sol GTA's and the Hytron GTs for the DR.

If I recall correct he likes a variety of 12ax7s in number one but for the DR and my taste we decided (If I remember) on a Tung-Sol. So all the way around he was talking me out of more expensive tubes.

I tried to order a quad of NOS Siemens for a HIWATT build and he just said flat no. They won't last 20 minutes. Gotta be British or Holland valves for that amp.

I tried to order a quad of NOS 5881 Tung Sols for a Blackface Showman build and got the same answer. It's the right tone mix but way too much voltage. So I didn't get my much desired RCA 6L6GCs either because I'm not sure what I'll run them in and he will only sell them in pairs now. They're almost gone. Probably a Super Reverb type with the voltage in the 450 range.

We all need to work on getting the tonal mix we want at lower voltage and current. The girls can't take it anymore!

Dan

[skyboltone]

why not use NOS 6CA7s?

Where? Who? How much?

[UR12]

If you need a chassis for that Hiwatt let me know.

[skyboltone]

If you need a chassis for that Hiwatt let me know.

I got three of them Dana, but I'm not going to build a 535VDC version. Just doesn't make sense to make an amp that distroys tubes for lunch.

I talked to Mark Huss about a KT-66 verstion at about 400. It would have to be revoiced but should be a lot easier on tubes.

Dan

[M Fowler]

Are you talking about the DR103?

The build instructions I have show 720v secondary 500mA/ 50V 10mA/ 6.3v 7A

720v with SS rectifier producing 460VDC, plates show 465 and screens 460.

OT is 2000 primary 4,8,16 100w rating (or anywhere from 1800 to 2200)

Mark

[skyboltone]

Mark Huss pages specification shows the transformer to be 375-0-375 at 250MA (Ok, I'm full of it. Here's the link:


http://mhuss.com/Hiwatt/tech.html


the above should be 700CT. I's wrong. Sorry, I must got so confused. The primary imp. is correct though for four tubes. I think that's too low. Just an opinion though) I believe. D103. In any case it's too many. Something more along the lines of 325-0-325 more better. And the OT is 1750 ohms. That's is an OK published number from Genelex but all the other manufacturers call for a pair into 6600 for normal AB1 operation. That of course would be 3300 out of a quad. I really dunno. Marshall, HiWATT and others use this weird 3450 PP load that I've only seen once in writing. A guy really should run the curve and do the arithmetic (Emax-Emin) over (Imax-Imin) after plotting the proper points on the family set of curves. That should be the design parameters. Those are incidentally the points used by Dynaco, Ken Fisher, and any number of Hi-Fi guys. Guitar amp manufacturers just like to keep the tubes pissed off.

Maybe that's the only way to get THAT sound but the manufacturers are going to need to make stronger tubes or we'll have to use tubes with 40 or 50 watt plate dissipations. And that doesn't even get into the subject of screens running 470 ohms south of the plates! Seems THAT sound comes from the meltdown and distruction of screen material and monster grid current/power.

We are designing for AB1 and running at times in Class B or C without the proper bias. It's no wonder we complain so much about tube reliability. The problem may not be them, it may be us!

Re read the Paulsters post. It's number two in the thread. Winged C is a good well made tube. Why do we have to run them so hot (towards class A) to get the tone? So they are alread hot right? The difference between the idle plate current and full load plate current in a class A amp is near unity. Near. And the grids never ever ever conduct. Now with that kind of low bias we hit it with a drive voltage (signal) that creates a conduction angle that runs the grids positive about 140 out of every 360 degrees. This is not good. Especially into low impedance loads.

[M Fowler]

This the schematic I have which is pretty squashed together.

I tried to clean up some of the info.

[skyboltone]

Are you talking about the DR103?

The build instructions I have show 720v secondary 500mA/ 50V 10mA/ 6.3v 7A

720v with SS rectifier producing 460VDC, plates show 465 and screens 460.

OT is 2000 primary 4,8,16 100w rating (or anywhere from 1800 to 2200)

Mark

Those are more like showman numbers. The showman runs 2100 with a quad of 30 watt tubes. Remember that the EL-34 really is a 25 watt tube. Your set up should last a lot longer than the higher voltage lower impedance iron. I'm going to build one, but I'm going to keep the tubes well within their values.

The problem though is how hard we push them. What you've described is very nice looking from a casual point of view. But put a volt meter on your output into the speakers and take a voltage reading. Baring in mind that the speaker impedance is only at it's nominal value within a very narrow range of frequency (low) and the rest of the time it's much higher. Which is a good thing. Now see how much actual power the tubes are producing at full roar.

I have a two tube Wreck clone design that puts out around 70 watts at full roar from two EL84!!! How many watts over design limit are we dissipating from those little guys? This is of course deceptive because it's not running into 8800 ohms all the time. at higher frequencies it's a much easier push.

JJ hold up the best so far, but Amperex sound sooooooooooo sweet by comparison. I just won't run them that hard. They are too nice to ruin with that kind of abuse.

[skyboltone]

Mark, How are you only getting 1.29 out of a cap entrance filter? I've never succeeded getting less than 1.36 or so. The formula is 1.41 at idle. The bias will pull it down a few volts. Most of the time they run about 1.37 or 38 for me. You should seeing about 500 volts on the plates and 499 on the screens. Especially with a 500ma monster. That's a nice transformer. Did Paul wind it for you?

[BobW]

why not use NOS 6CA7s?

Where? Who? How much?

The NOS are rare and hard to find but the EH 6CA7s IMO sound better than the EL-34s.

I have a two tube Wreck clone design that puts out around 70 watts at full roar from two EL84!!!

70W from two EL84s?

[skyboltone]

That's correct BobW. Amplifiers are (when honestly described) rated at the point just before the onset of crossover clipping. When running full roar in distortion they push far more current and voltage into the load. Try it yourself.

[skyboltone]

Bump. I lied last night