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Isabellina HPA - Owner's Thread and Impressions
Apr 8, 2011 at 6:51 AM Post #421 of 532


Quote:
winzzz said:
the inside looks nothing exceptioanal...whats so special about this amp ?
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The sound!! 
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Apr 20, 2011 at 7:22 PM Post #429 of 532

Hi all,
 
I haven't really had time to write out a full review of the Balanced Isabella so I've instead decided to present my scattered impressions.
 
Sorry these have taken so long, and I'm sorry that they are so short. I spent hours and hours burring in different sets of tubes only to get laid up by a nasty cold for the past week. I haven't been able to do as much listening as I'd like due to my head being plugged up. Let me know if you have any specific questions and I'll try and answer them for you.
 
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My Headphone Rig​
 
Disclaimer - These are my thoughts and my thoughts alone. As always YMMV. Also sorry for the crappy iPhone pics.
 
 
Without further ado, my thoughts:
 
The Bad News
 
I always like to hear the bad news first, so lets get the bad news out of the way. One comparison I'm dying to do is unfortunately the one I've been unable to do. I really want to compare the Balanced Isabella against the Isabellina HPA. Unfortunately, I traded in my HPA when I purchased the Isabella, so I no longer own one. However, I've been in touch with another HPA owner, and I hope to do a mini-meet with him at some point down the road where we can compare and contrast the different Red Wine units.
 
The other bad news is that I haven't been able to try the Isabella as a Preamplifier in my home stereo system yet as some of my other components are out for repair. Thus far, I've only been able to evaluate the Isabella as a headphone amplifier and dac.
 
The Good News
 
Now, for the good news. The Balanced Isabella sounds fantastic! If I had to use a single adjective to describe the way it sounds, I'd have to use the word "Transparent." The soundstage is big and clear, the bass is tight and punchy, and the overall balance of the presentation is very pleasing. I really can't think of any aspect of the sound that I'd really like to change, provided you switch to higher-grade tubes (more on that later).
 
Comparing the Isabella to the Isabellina solely on memory, I'd say the balanced Isabella sounds clearer in the top end, has a wider soundstage, with sharper imaging and punchier bass. From what I have read, these are exactly the types of benefits that are typically associated with balanced drive vs. single ended. I didn't remember any huge differences in the presentation of the mids when using the stock JJ tubes, but again, I don't have an HPA on had to compare this to.

 
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LCD2s Plugged Into The Balanced Headphone Stage​
 
I've enjoyed listening to just about every genera of music on the Balanced Isabella, but I particularly love it for the way it does classical and jazz. Before I purchased the Isabella, Vinnie told me that the new balanced headphone output stage had significantly more gain than the production model headphone output stage. I'm guessing the additional gain in the balanced headphone output is really helping out on those classical and jazz tracks that are mastered with tons of headroom. With the new stage, I can crank the volume to the point where it sounds just right and really dig out the detail in the quieter passages. Everything sounds crystal clear with the new stage, even at the high volumes.
 
The Isabella does have a toggle to add an additional 12DB of gain, but thus far I haven't had any need for it. Even at low gain, I have no doubt that the balanced headphone output stage should have plenty of power to run K1000s or HE6s.
 
One thing to note, to my ears the Balanced Isabella has a higher noise floor out of its headphone output than my Isabellina HPA did. While the noise floor is essentially inaudible when playing music using full-size headphones, I would not recommend plugging IEMs or other super low impedance headphones into the balanced headphone stage. With IEMs you are going to run up against the noise floor. IEMs also don't need anywhere near the power the Isabella is capable of providing.
 
Battle of the Balanced Amps
 
The first weekend I had the balanced Isabella, I had a chance to take it to a mini-meet and compare it with an EHHA balanced amp based on a DIY design form Cavalliaudio.com. We did a "battle of the balanced amps" at the meet and blind tested them to see if we could tell the two amps apart.

 
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The EHHA amp used in the "Battle of the Balanced Amps"​
 
Our test went as follows. We were careful to make sure the only major difference in the two signal chains was the amp. To test only the headphone amp functions of the Isabella, we decided that we needed to bypass the onboard Red Wine Isabellina DAC (more on this later). We connected a PS Audio III DAC with multiple sets of analog outputs to the analog inputs on the EHHA and the Isabella. We used my pair of Sennheiser HD800 headphones to perform the test. The signal chain therefore used the same source (PS III DAC), different amps (Isabella and EHHA), and the same headphones (HD800s). The interconnects used to connect the DAC to the amps were identical.
 
For the actual test, the listener was free to chose a 30 second selection of a song and volume match the two amps so that the levels were equal on their given selection. This part of the test was not done blind. During the volume matching section of the test, the listener was free to pickup on any sonic differences between the two amps.
 
I figured that a simple A/B test would be far too easy to guess right. Rather than repeat trials ad nauseam to eliminate the effect of guessing right, I designed the test in the following manner. Once the levels were matched, the listener would turn and face out the window while the tester played the listener his chosen 30 second selection 3 times with 15 second gaps in between. The listeners job was to guess which amp they were hearing during each of the three trials. The listener would not take the headphones off his head for the duration of the test.
 
During the 15-second gaps between repeats, the tester randomly chooses which amp to plug the HD800s into. To avoid pulling any dirty tricks, we set a ground rule that both amps had to be played at least once in each 3-trial test. With only this one ground rule, the tester was then free to choose any permutation of amps for the three trials. Examples of test runs included:
 
Isabella, Isabella, EHHA
Isabella, EHHA, EHHA
EHHA, Isabella, EHHA
Etc.
 
The listener was then asked two questions. Question #1: Which two trials were on the same amp, and Question #2: which amp was played twice.
 
Crazily enough, none of the three head-fiers (including myself) could answer both questions correctly over repeated tests. We struggled equally with each question. We were as unable to identify any distinctive "Red Wine Sound" as we were to distinguish an "EHHA sound." While we often believed that "heard" one trial as being punchier than another or smoother than another, we were often dismayed to find that those two trials were done on the same amp. We also failed to differentiate the amps when we swapped out the HD800 for my pair of LCD2s.
 
I had heard this particular EHHA at an earlier mini-meet and I was blown away by it, so I was actually quite pleased that we weren't able to distinguish the Isabella from it.
 
While I was initially surprised with this result of our blind testing, the more I think about it, the more it makes sense. I take the following from our failure to differentiate the two amps in the battle of the balanced test: In a sense, the job of an amplifier is to amplify, not to color. One might expect amps in the same class to amplify roughly as well as one another as long as neither is adding extra color to the sound.
 
Though the parts cost on the EHHA was roughly 2k (including casework) compared to the 6k retail on the Isabella, we cannot overlook the fact that the EHHA was a DIY project while the Isabella was purchased fully built from a manufacturer. When you consider the additional costs a manufacturer has to endure in selling completed units vs. simply selling parts, it is easy to see how the manufacturer would need to charge at least 2x or 3x the parts cost in order to make any profit. Advertising and brand development, labor and assembly, product support and warranties, sending out review units, attending audio shows… all these things cost money. In some cases, a lot of money. When you purchase a fully built unit from a manufacturer, you are in part paying for these extra services.
 
With that in mind, even though the parts cost on the EHHA is only 1/3 of the cost of the Isabella, they most likely are the same class of amp. It should therefore probably come as no spurs have a similar, very high quality sound.
 
The Isabellina DAC
 
As far as I know the Isabella has the exact same DAC as the Isabellina HPA. Heck, the HPA is really just a $2,000 DAC with a $500 headphone output, right?
 
While at the mini-meet where I conducted the "Battle of the Balanced Amps" I also had a chance to DAC-roll the Isabellina DAC and A/B it against the other two DACs present. I set up both the Isabella and the other DACs to output into the two analog inputs on a Woo Audio amp. The Woo had a switch on the back so you could instantaneously switch from one input to the other and back again. These DAC-rolling tests were not performed blind.
 
To my ears, the Isabellina DAC was a winner over the Meier StageDAC. The RWA was punchier and head better dynamics.
 
The comparison between the Isabellina DAC and the PS Audio III was much closer to call. Though the two DACs definitely sounded different, it was very difficult to say which sounded better than the other. In the end, I thought that the Isabellina was ever so slightly more detailed than the PSIII. However, as the test was not conducted blind I figure the differences between the Isabellina DAC and PS III were well within the margin of error or I might have just been imagining things. That isn't to say the two DACs sounded the same. They didn't. I'm only saying that it was very hard to pick a winner between the two given the test conditions.

 
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Close-up of the Isabellina DAC Chip Inside The Case​
 
After DAC-rolling, I thought about all the reviews I have read that attribute a certain "house-sound" to all the RWA products. I think I know where they coming from. I believe they are hearing is the Isabellina DAC. Having had a chance to A/B three very good DACs I really had a chance to appreciate the different flavors they brought to the sound. While I might not have been able to clearly say whether I liked the best, the Isabellina DAC has a distinct sound that is clearly giving the RWA gear some of its flavor.
 
Tube Rolling the Isabella
 
If you ask me, tube rolling any of the Red Wine Audio units is a necessity, be it the Isabella, the Isabellina HPA, or anything else. Decent to high-end NOS tubes will change the sound of the Red Wine gear pretty dramatically. If you are still using the stock JJ tube(s), I would highly recommend upgrading the tubes in your rig before upgrading anything else.

 
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The Stock JJ Tubes Where They Belong - On Your Desk. Not In Your HPA​
 
Back when I owned the HPA, I had experimented with tube-rolling a number of tubes in the $20-$40 price range. My experiences with tubes in this price range were not all that positive. I found that while many tubes sounded better in one particular area of the presentation, rarely did they put together a "total package" that was clearly better than the stock JJ. For example, while a tube like the GE smoked glass tubes Ken Ball mentioned in his post earlier in the thread seemed to have better bass and a warmer presentation in the mid-range, I was not so fond of the way it sounded in the highs.
 
After trading in my HPA but before receiving the Isabella I had a chance to tube-roll with another head-fier who had picked up same significantly more expensive NOS tubes in the >$200 price range. I couldn't believe the difference they made in his HPA! Unlike many of the cheaper tubes I had played around with, one tube in particular sounded absolutely amazing and seemingly improved upon the stock JJ in every way. Although the tube was expensive, IMO you absolutely get what you pay for. Lets be honest, if you can afford to spend $2,500 on a HPA you can afford another $200 tube to make it sound its best. Any money spent on higher-end NOS tubes will be money well spent.
 
After that experience, I knew I would have to purchase some high-end NOS tubes for the balanced Isabella. While the balanced Isabella sounds really good with the stock JJs, when you upgrade to something like a Siemens CCA or an Amperex Pinched-Waist the sound is absolutely stunning.
 
Detail freaks (like myself) will love the way the balanced Isabella and the Siemens CCA pairs with the Senn HD800. Of all my gear/tube parings with the Isabella, this is my personal favorite. I've never heard the HD800s sound better on any system at any price. The soundstage is huge, the imaging is razor sharp, and the bass is very tight and punchy. The midrange is quite neutral with the Siemens, though, so those looking for that warm tubey midrange should look elsewhere. The sound with the CCAs might be a bit more analytical than it is musical, but it happens to really suit my tastes.
 
Those looking for the more traditional tubey sound with a warm, rich midrange will want to look for something like Amperex Pinched-Waist tubes. I found the Amperex's to be a perfect match with my LCD2s. While the Amperex's seem to be a more mid-focused tube than the Siemens CCAs, their extension into the highs and lows is still miles ahead of the stock JJs, and they have a really beautiful tone with an emphasis on a liquid mid-range.
 
I had originally ordered both the Siemens and the Amperex with the intention of only keeping one of them, but I like their different flavors so much that I decided to sell some gear and keep both.
 
In a sense, in tube rolling the RWA gear you really get to pick your flavor. All the tubes I have tried in the Isabella drastically changed its sound, and often for the better. By tube rolling the various NOS brands and models I ended up finding some wonderful combinations that I can listen to for hours on end. Just don't forget to fully burn in the tubes before you make any judgments! I strongly suspect that if we repeat the "Battle of the Balanced Amps" with some NOS tubes in the Isabella instead of the stock JJs that we wouldn't have any trouble figuring out which amp was which.
 
One thing that bothers me here is that you never see professional audio-reviewers tube-roll the RWA products they are reviewing. Though there are a number of places where I think the reviewers would really benefit from tube-rolling, I'm thinking in particular about Srajan Ebaen's review of the Isabellina HPA linked here. Reading his review almost read more like a review of why the Burson is great and the HPA isn't. I would venture that if Mr. Ebaen had a chance to re-review the LFP-V HPA with a top-of-the-line NOS tube in place, he might not be so quick to declare the Burson the clear winner over the HPA. We all have our subtle preferences in how we want our music to sound, and, from my experience I think that a different tube "flavor" might have done the trick for Mr. Ebaen.
 
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The Tube Access Window - The Rest of the Line Needs This Feature!​
 
One last thing… the easy-access window on the Isabella is a godsend for tube-rolling. IMO, Vinnie absolutely must bring this feature to the LFP-V HPAs. It is so nice to just slide the window open rather than having to unscrew the top-case any time you want to switch tubes.
 
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The Window Makes it So Easy To Roll Tubes!​

 
My Final Thoughts (For Now)
 
The balanced Isabella is certainly not a value proposition. Between the 6k retail price, NOS tubes and headphones we are talking about roughly 10k worth of gear here. For that money, it had better sound damn good, and, quite frankly it does. I am very happy with the purchase.
 
Apr 21, 2011 at 10:11 PM Post #433 of 532
Nice review. Well writen, I read every word. Comments on pinched waist were interesting. I had several balanced rigs before going all RWA (best was First Watt F1 with balanced k1000s / silver dragon - switched because RWA had more natural tone to my ear). Looks like now you can have the best of both worlds.
 
Apr 21, 2011 at 11:53 PM Post #435 of 532

Thanks for the feedback on my impressions everyone. I appreciate it. Don't hesitate to let me know if you have any specific questions.
 
Quote:
brasewel said:
It's unfortunate you couldn't compare the Isabellina HPA to the Isabella since we're talking about a $3500 difference here.
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I totally agree with you on this. I'm hoping to get a chance to meet up with an HPA owner in a few weeks to compare and contrast and I will be sure to post impressions here if that happens.
 
I will mention again that I bought the Isabella with the intention of using it both as a headphone amplifier and as a preamplifier in my main stereo setup. Just going of my memories of how the HPA sounded, I might hesitate to recommend the upgrade from the Isabellina to the Isabella if you were only going to use it for headphones. As you noted, the cost increase is more than 2x. I'm guessing most will still hear a benefit from going to the Isabella from the Isabellina even without having the balanced headphone stage. The reason why is that the headphone amp in the Isabella runs directly off of one of the preamp outputs (and hence uses the entire preamp signal path, FWIW) while the Isabellina (if I am remembering correctly) runs off a buffered output from the DAC chip. 
 
My ability to make a recommendation may change once I've had a chance to sit down with the original Isabellina HPA and do some quality A/B testing. I'd love to do another blind test with the Isabellina HPA, and I'll try and see if I can think something up.
 
Finally, as I mentioned in my impressions, if you are an Isabellina HPA owner and haven't upgraded the stock JJ tube then you are going to notice big changes by going out and purchasing a quality replacement. The differences in sound IMO are substantial, and even the most expensive tubes like the Amperex Pinched-Waist won't run more than $300.
 
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