Why is the Wheatfield so hard on tubes?

[Dusty Chalk]

I know it runs them hot, is that the entirety of the reason, or is there more to it than that?

Also, is it hard on the power tube, the rectifier, or both?

Anyone know Pete Millet? Anyone want to ask him for me (diplomatically, of course)?

Any good current production tubes for them?

[Guest sacd lover]

I know it runs them hot, is that the entirety of the reason, or is there more to it than that?

Also, is it hard on the power tube, the rectifier, or both?

Anyone know Pete Millet? Anyone want to ask him for me (diplomatically, of course)?

Any good current production tubes for them?

1) Why do you think the amp is hard on tubes?

2) answer question one

3) Not me!

4) No .... not IMO.

[kevin gilmore]

I agree with number 4.

There are however tons of tungsol NOS 6080's available.

[Dusty Chalk]

Thank you all for your helpful responses.

1) Why do you think the amp is hard on tubes?

Because mine keep burning out. And I know of at least one other owner that goes through a lot of tubes as well.

I'm looking for the best option for (a) driving low impedance headphones and ( at a non-expensive rate. According to Pete Millet's HA-2 tuberolling faq (PDF), it says I should go for a 6528a -- Mikhail happen to get any of those that he would be willing to sell me? TDSL says I should also look at the CV9094 -- same question.

Any other good recommendations for tubes for driving low impedance headphones? When I looked up all the tubes listed in that FAQ, and cross-referenced them in TDSL, I expected to see them come up as each other's substitutes. And yet, they did not. Any idea why?

I'm also wondering if there are any tweaks that I can do to get them to not eat up tubes like Killdozer. Is there a way to lower the supply voltage? Do I want to do that? Is there something I can look at in the power supply, to make it more stable? Any other brilliant suggestions?

A specific question to KG, 5687, and anyone else who would say "no" to #4 -- do you believe in current production tubes at all? I say this not to start that argument, but just as a reference point. I, myself, have heard some good new production tubes that I like (although I admit -- none of them were more powerful than the EL84, which KG has already told me sucks). I also ask because as a follow-up question -- is there a way to rewire and/or replace the socket so that I could put a good current production tube in there? Or an adapter?

I'm probably just going to sell the fucker and be done with it, but it's such a nice complement to my Singlepower amp that I really would like that sound as an option in my headphone listening. Do you know what I'm talking about? Can I get an 'amen'?

Would the 6080 be a good choice for low impedance headphones?

[Guest sacd lover]

Thank you all for your helpful responses.Because mine keep burning out. And I know of at least one other owner that goes through a lot of tubes as well.

I'm looking for the best option for (a) driving low impedance headphones and ( at a non-expensive rate. According to Pete Millet's HA-2 tuberolling faq (PDF), it says I should go for a 6528a -- Mikhail happen to get any of those that he would be willing to sell me? TDSL says I should also look at the CV9094 -- same question.

Any other good recommendations for tubes for driving low impedance headphones? When I looked up all the tubes listed in that FAQ, and cross-referenced them in TDSL, I expected to see them come up as each other's substitutes. And yet, they did not. Any idea why?

I'm also wondering if there are any tweaks that I can do to get them to not eat up tubes like Killdozer. Is there a way to lower the supply voltage? Do I want to do that? Is there something I can look at in the power supply, to make it more stable? Any other brilliant suggestions?

A specific question to KG, 5687, and anyone else who would say "no" to #4 -- do you believe in current production tubes at all? I say this not to start that argument, but just as a reference point. I, myself, have heard some good new production tubes that I like (although I admit -- none of them were more powerful than the EL84, which KG has already told me sucks). I also ask because as a follow-up question -- is there a way to rewire and/or replace the socket so that I could put a good current production tube in there? Or an adapter?

I'm probably just going to sell the fucker and be done with it, but it's such a nice complement to my Singlepower amp that I really would like that sound as an option in my headphone listening. Do you know what I'm talking about? Can I get an 'amen'?

Would the 6080 be a good choice for low impedance headphones?

Sure ... I have no doubt Mikhail would sell you a 6528. Now random thoughts .... the 6528 takes 5 amps of heater current and the 6080 only takes 2.5 amps .... are you sure the amp can handle that? Thats why the 6528/6080 arent listed as subs for one another .... because their operating parameters are considerably different. A 6080 doesnt like lots of voltage and that may be why they are dying quickly. The 6528 can definitely handle more voltage and if the amps power or filament transformer can handle the heater current draw .... the 6528 is surely more rugged. Mikhail has some of the seriously overbuilt Bendix 6080's and that might be another option if the amp can handle the 6528's heater current requirements.

I would tone down the amp and continue to use nos tubes myself. There is also the Russian 6as7 thats more rugged than the typical nos 6080 but I dont like the sound quality .... but you might. This tube will plug right in as its the same pin out and generally the same tube; just more rugged.

A single 6080, used OTL, is not a very good tube for low impedence headphones. The 6080 has to high of an output impedence OTL. If the tube is transformer coupled the tube is very powerful and will drive low impedence headphones very well. I dont remember if the Wheatfield is OTL or OPT coupled.

[n_maher]

Anyone know Pete Millet? Anyone want to ask him for me (diplomatically, of course)?

I'll leave the other questions to the tube experts but I can handle this one. I've had several email conversations over the past 2 years with Pete mainly focused around my work on the development of the modified Millett Hybrid layout. I was going to tell you to just email him but he seems to have taken the address off of his website. So I'll shoot him an email tomorrow and see if he gets back to me, he's never given me the impression that he minds people asking questions and has always been really approachable. Also, you might try contacting Headroom about the amp since they sold Wheatfield gear for a short time and see if they have any insight into your issues.

[Dusty Chalk]

I'm pretty sure it's OTL. (double-checks) Capacitor coupled OTL, according to this page.

Oh, and I got the idea about using a 6528 in it based on Pete Millet's own HA-2 Tuberolling FAQ (which I linked to previously). It's explicitly suggested for low impedance headphones. So yeah, I'm pretty sure it can handle it. Not positive, but pretty sure...why wouldn't it? Because the draw might be more than the power reserves are capable of? So maybe I should supplement the power reserve caps?

WRT email: No, it's there -- right on his front page. I guess I could email him, I just wasn't sure how approachable he was, and I wasn't sure how to ask the question. Actually, now that I think about it, I have another question to ask him, so I will definitely email him.

[pabbi1]

Pete always answers me as well, albeit with a few days lapse. I ran a 7236 (with Senns) and it lasted about a year and a half of 25+ hours per week. I had a 421a for low impedence (for the few times I ever used Grados).

[kevin gilmore]

yes i believe in some current production tubes. Unfortunately virtually none of them

are usable for audio unless you are completely nuts.

Eimac (now independent again) makes wonderful ceramic triodes and tetrodes.

The new western electric makes some pretty good 300B's. Way better than any

other chinese junk, but still not as good as the originals.

Hammamatsu makes some truely amazing products. In fact they make an amplifier

tube so linear (and 50 ohm output) that works great as a headphone amp tube.

Trouble is they are about $650 each. You need 2, and they would last virtually

forever.

Watkins-Johnson makes some very nice stuff too. They also make a 50 ohm output

ultra low noise amplifier tube. You don't want to know the price.

[Dusty Chalk]

Hammamatsu makes some truely amazing products. In fact they make an amplifier tube so linear (and 50 ohm output) that works great as a headphone amp tube. Trouble is they are about $650 each. You need 2, and they would last virtually forever.

So...you've already designed one, yes?

Watkins-Johnson makes some very nice stuff too. They also make a 50 ohm output ultra low noise amplifier tube. You don't want to know the price.

Yes, I do.

[kevin gilmore]

Yes i have designed one.

The wj211 tube last time i checked was about $8900 each. You need 2.

4 for balanced.

[Dusty Chalk]

...cough...choke...wheeze...

[Dusty Chalk]

I had no idea.

[n_maher]

poof

And just like that the Orpheus became "cheap".

[Tyll Hertsens]

God! You guys are giving me wet dreams. We have the new HA2 on the schedule for 2008, and I can't wait; and someday we'll do a 300B that Pete wants to design. But, Keven, you little prancer you, that little Hamamatsu amp sounds interesting. A tube amp that would last forever sounds like a HeadRoom kind of product. What tube is it?

And don't be shy to get a hold of Pete, he's one of the all time nicest guys, and wickedly good tube guys I know.

[Large4mat]

We have the new HA2 on the schedule for 2008, and I can't wait

That's what I'm talking about! I for one will be watching closely for the release.......

I haven't worn out a tube in mine yet, but the amp does run extremely hot. I've only owned the amp for a few months, and use my amp around 15 hours a week. The heat issue has always concerned me; the top of the map is almost too hot to touch after about 30 minutes of operation. I don't use Grados with mine.....(Not a good match IMHO). That being said, the 7236 will work with the Grados, (and very well with the Senns). If anyone gets in touch with Pete, please post or pm with his comments..........

[pabbi1]

Enjoying that Wheatfield (sniff), are you?

[Dusty Chalk]

No, not really, I'm really kind of pissed off at it right now.

[Large4mat]

Enjoying that Wheatfield (sniff), are you?

I think Al was directing this towards me........Sorry to hear about your amp woes. I hope Peter can get the bugs worked out for you. And yes, I am enjoying your old Wheatfield. It is without a doubt the most musical amp I've ever owned.

[Large4mat]

No, not really, I'm really kind of pissed off at it right now.

Which tube(s) are you having trouble with? How many hours are you getting out of them before they die?

[hirsch]

Note that many of the tubes for the Wheatfield are not particularly long-life. For example, the 6080 is rated at about 2000 hours. Bad idea to expect this tube to last very long if you're using the amp a lot.

[Dusty Chalk]

Which tube(s) are you having trouble with?

It appears to be both the rectifier and the power tube. I've only measured them once, so I may have only had one good rectifier before.

How many hours are you getting out of them before they die?

I haven't been that scientific about it. I will be with my next tubes, though. And as Hirsch pointed out, my complaints may well be within the normal range.

[Dusty Chalk]

So how does one find out what tubes the Wheatfield was specifically designed for?

The reason I ask is, when looking at his tuberolling FAQ, Pete Millet mentions several tubes:

6080

6AS7(-G)

5998

7236

6528(-A)

...and when looking these up in TDSL, they don't show up as substitutes for each other. I figure that the amp is sending the same bias voltage &c. to the tubes, but they all might react differently, having different ratings.

Also, how does one look up the Zout on these? It doesn't show up in TDSL for all of them (nor in the linked data sheets). Is that the best way to figure out which ones are best for low impedance headphones? Right now, all I have to go on is 6258A (and according to TDSL, the CV9094), but I don't know why that one is best for low impedance headphones.

[hirsch]

So how does one find out what tubes the Wheatfield was specifically designed for?

One reads your link more closely. Since the standard tube supplied was the 6080WC (for power), Sovtek 5U4G for rectifier, those are good bets. He probably used a 6SN7EH, or maybe a JAN 6SN7GTB (common and cheap). That may be in the manual, but I haven't looked. Usually, it's pretty safe to assume that an amp comes with the tubes it's designed for. That does not mean that those are the tubes that work best in the amp.

There are two parameters that will indicate whether or not a tube will be good into low impedances. One is output impedance. Low is better. The other is output power. High is better. I'm being overly simplistic, but that's the bottom line.

The HA-2 was not really designed for low impedance headphones, even though it can drive them with judicious tube selection. If you draw the line at 100 ohms, you get to use a wider variety of tubes, including most of the ones that sound great. K-701 is low at 62 ohms, but is still better than Grado's, Audio Techica or Sony. K-1000 at 120 ohms is great. Beyer and Sennheiser are probably the best easily available cans for the amp (but check specs for a particular model to be sure).

[Guest sacd lover]

So how does one find out what tubes the Wheatfield was specifically designed for?

The reason I ask is, when looking at his tuberolling FAQ, Pete Millet mentions several tubes:

6080

6AS7(-G)

5998

7236

6528(-A)

...and when looking these up in TDSL, they don't show up as substitutes for each other. I figure that the amp is sending the same bias voltage &c. to the tubes, but they all might react differently, having different ratings.

Also, how does one look up the Zout on these? It doesn't show up in TDSL for all of them (nor in the linked data sheets). Is that the best way to figure out which ones are best for low impedance headphones? Right now, all I have to go on is 6258A (and according to TDSL, the CV9094), but I don't know why that one is best for low impedance headphones.

The 6528a, along with the 6336, is the most powerful tube in the series @ 30 watts dissipation per triode section vs 13 watts per triode with the 6as7/5998/6080/7236, .... and the 6528a also has the lowest output impedence. The trouble with the 6528a and 6336 is the tube demands 5 amps of heater current per tube vs 2.5 amps for the other tubes.