Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › EAR HP4 Tube Rolling Thread
New Posts  All Forums:Forum Nav:

EAR HP4 Tube Rolling Thread

post #1 of 78
Thread Starter 
You knew this was only a matter of time, didn't you?

The stock tubes are Sovtek 6SL7GT's. Tim de Paravicini says that the EAR was designed for these tubes, and that the sound cannot be improved by changing them. What does he know? He just designed the thing. The EAR does sound pretty good with the Sovteks. My first experience was at the Headroom World of Headphones Tour. The initial sound was very peaky, with lean bass and a hopped up treble range. Bleh. An hour or two the story was different. The amp had a new clarity, and showed that it was indeed a high end amp...enough so that when opportunity to own one knocked, I opened the door.

There is a catch to tuberolling the HP4. 6SL7's come in two main sizes: short and tall bottle. However, the case of the EAR is so low that a tall bottle tube can't fit in the amp if you want to use the cover. Given the voltages that run in a tube amp, and the four cats I'd like to keep, a cover is a good idea. For the time being though, my audio rack closes with a glass door, and I run without a cover using a tall-bottle tube. All impressions are using the Sony R10.

There are going to be several posts, but I'm going to start by getting some of the crappiest tubes I've tried out of the way. RCA. Bleh. I've tried a couple of different types, and nothing good has happened. It sounds like something should be happening, but both the lows and the highs are recessed, and dynamics were poor. This is true of the regular RCAs. I also have a set of Hewlett-Packard 6SL7GT's that appear to be coin-base RCA's. Terrible tubes.

PhillipsECG 6SL7WGT (black base). The W in the type indicates a tube designed for ruggedness and low microphonics. These should have been very clean tubes, with a tendency to a bright high. Instead, they were ultimately nothing special. Cleaner than RCA's, but not by much. Again, the dynamics seemed to be compromised. This was not my initial impression, but was formed after listening to those tubes alone for a couple of weeks. It became very clear I could do better.

to be continued...
post #2 of 78

Tubes for the EAR HP-4

Hi Hirsh,

I understand you very, very well. As you know I had the EAR HP-4 and I done a lot of experiment with many kinds of tubes: nothing! Even my designer (that built the R-10H) had a long try with my EAR, he even phoned to Tim De Paravicini, but seems that the HP-4 works only with the Sovteks tubes. (But in my ex. the best sound was with the Sylvania tubes). Ask to Jatinder how many mails between us for these experiments with different tubes in the EAR. After all this I resolved to sell the EAR and to build a better amp for the R-10, and this is reality now! As you said the R-10 needs a lot of power to sound with all the possibility and certainly the EAR do not has all this power.


Nicola
post #3 of 78
Thread Starter 

Re: Tubes for the EAR HP-4

Quote:
Originally posted by Nik
Hi Hirsh,

I understand you very, very well. As you know I had the EAR HP-4 and I done a lot of experiment with many kinds of tubes: nothing! Even my designer (that built the R-10H) had a long try with my EAR, he even phoned to Tim De Paravicini, but seems that the HP-4 works only with the Sovteks tubes. (But in my ex. the best sound was with the Sylvania tubes).
Hi Nik,

That was only the first part of the story. There's more to come. Tim De Paravicini is dead wrong when he says the EAR only works with Sovteks. I've found two different combinations that are far superior, which I'll post about shortly.
post #4 of 78

RCAs

It's interesting that these are no good in this app, since some of their similar 6SN7s are very nice.
post #5 of 78
Hirsch,
If possible, it would be great if you could someday do a post in which you rank amplifiers in terms of their ability to benefit from tube-rolling. That is, which amps were transformed the most through all your vast tube-swapping experiences? Where does the Ear stand on that scale?

I ask because I heard the Ear at the Headroom meet (I know, the worst possible way to audition), and I really wanted to like it. I spent a long time with it, but it just didn't make me go "WOW" with my R10s-- although it was certainly not a "bad" amp by any means, I liked it, but not enough to really lust after it. I assume that unit had stock tubes.

And what about an Orpheus tube-rolling thread? jatinder?

Mark
post #6 of 78
Thread Starter 
Quote:
Originally posted by markl
[B]Hirsch,
If possible, it would be great if you could someday do a post in which you rank amplifiers in terms of their ability to benefit from tube-rolling. That is, which amps were transformed the most through all your vast tube-swapping experiences? Where does the Ear stand on that scale?
Of the ones I've tried, the ZOTL is the most complete chameleon. You can completely change the character of the amp with the tubes selected. The Moretto HAP-03 (possibly deceased) also dramatically changed quality with tube rolling. There was less effect with the X-Can or with the SHA-1, I think due to the hybrid nature of the amp. These amps retain their personality regardless of tubes used, but tube rolling can refine their sound, rather than change it. The EAR falls somewhere in the middle. I think the output transformer reduces the effect of tuberolling somewhat, but not to the extent a solid state driver stage does. If you heard the EAR early at the Headroom tour, you didn't hear it at its best. I couldn't get my self to like it early one, but it sounded completely different with a couple of hours warmup behind it...to the point that I didn't hesitate when I had a chance to buy one. Once I got it home, I've been playing with different tube combinations, which I will post about in this thread. The EAR and the ZOTL can sound surprisingly close. One thing I did learn from the EAR was just how well David Berning designed the ZOTL...the two can sound very close together. However, the EAR can muster up a sense of power and authority that the ZOTL doesn't quite reach.

I'm meeting with a plastics guy tomorrow, to see about having an acryllic case made for the EAR that will let me use tall-bottle 6SL7's, which will broaden my choices a lot. I'd run it without the case, but I've also got four cats, and would like to maintain that number (voltages in tube amps can run high)
post #7 of 78
Four cats??? I've got two and they're a handful!! Especially the one whose favorite hobby is to go behind my audio rack and chew on all my expensive cords! I'm too much of a softy to discipline him though-- how can he possibly understand why he shouldn't chew my cords??? Luckily, so far he's never been shocked or electrocuted!

Mark
post #8 of 78
Markl: Have you tried covering your cables with copper corrugated tubing? It's the ribbed stuff they use for water heater connections, it should come in a bunch of sizes, and if you put that around your interconnects your cat(s) will need an angle grinder.
post #9 of 78
eric,
sounds good-- where can I pick it up? Local Home Dept?

Mark
post #10 of 78
eek:

Quote:
Originally posted by Hirsch
The Moretto HAP-03 (possibly deceased) also dramatically changed quality with tube rolling.
Yow! What happened????? Surely not the kitties..?
post #11 of 78
Thread Starter 
Quote:
Originally posted by daycart1
eek:



Yow! What happened????? Surely not the kitties..?
Transformer blew, I think. Lots of sparks and pyrodynamics. David Moretto has been trying to get me a replacement. He got two sent over, and both blew up on his test bench. Prospects of getting that amp working again appear poor.
post #12 of 78
That's amazing! (and too bad, sorry man). I've only got about 40 hours on mine since I mostly listen to the Zotl. I wonder if its days are numbered as well?
You were running it through the Monster conditioning strip?
post #13 of 78
Yes, Home Depot should have it...

One more benefit is that if you ground it, it'll make one heck of a shield... Probably impervious to EMP
post #14 of 78
Tube rolling in head. Amp.

I even have a chance (just one) to try another kind of tube for the R-10H amplifier, but first I want to tell you that my R-10H is the only (between the amps we are speaking) that has a tubed power supplay, (a Mullard is inside). I’m not a technician: changing the tube in the power supplay it is possible to hear any different in sound?

I ‘d can to change the 2 Sovtek 6C45 (in use) for the Wester Electric 437A, that is a lot more expensive than the Sovtek, but this needs to change even a resistor in the amp. Someone know this tube?



PS:
Thanks to Good... I have not any animals in my house (!!!)
post #15 of 78
Thread Starter 
There's a problem with rolling tubes in the HP4. Tim de Paravicini designed the amp to run on Sovtek 6SL7GT's. In fact, the case itself reflects this. However, the Sovtek is a short bottle tube. The problem is that some of the best 6SL7GT's are tall bottle tubes:



Note the tops of the tubes appearing over the metal rail. The case sits right on that rail. Try and install the case, and you'll decapitate the tubes. These particular tubes are 60 years old and deserve better treatment than that! I've been running the EAR open (see the DC meet pictures), but I have cats, and there's serious voltage in there. So, I had to come up with a solution:



I designed this and took my drawings to a local acryllic expert who built it for me. Note the holes on the base at one side to encourage air flow. It fits onto the EAR perfectly:



The clear top gives a nice view of the circuit board that the tubes. I think I developed a liking to see the boards from the design of the ZOTL case



Rear view, showing the single ended and balanced I/O jacks. All in all, I think this looks better than the original case. My cats are safe, and I can now use any 6SL7 I want and still have a cover on the amp. Life is good
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › EAR HP4 Tube Rolling Thread