[L0rdGwyn]

Nelson Pass has been pushing this line for a while now. Some of his designs deliberately have more 2nd order distortion because they consistently perform better in listening tests that way. One of the key reasons why different operating points for tubes sound different is because it changes how much 2nd and 3rd order distortion is present as well.

You took the words right out of my mouth, I very nearly quoted Nelson Pass in a recent post. I recall an interview where he described how Pass Labs minimizes distortion in their products, but they attempt to keep whatever distortion is left as second harmonic due to it being more subjectively pleasing.

A few years ago, Bob Katz wrote an interesting article on Innerfidelity where he built a second harmonic distortion generating circuit, such that he could finely tailor the amount of second harmonic injected into his system and do subjective comparisions. The results are very interesting, it is a good read:

https://www.innerfidelity.com/content/katzs-corner-episode-25-adventures-distortion

I have tried to reason with hardcore objectivist audiophiles on the merits of second harmonic distortion and tube audio, it never ends well. My sources have been described as "half-baked opinions" among other things, but I think those guys Bob Katz and Nelson Pass know a thing or two.

 

[DecentLevi]

I am not getting notifications ether
Shipped a amp today
And building Zachi's amp now.

Oh, which username is Zachi, or is that his name here? And is he getting a SET amp? I'm interested to finally read any more impressions on one of yours.

Also would you mind to mention how @carlman14 is lookin' in the queue? I was hoping his OTC SET amp may be ready for my Seattle meet the last Saturday of the month.

 

[heliosphann]

I'm back! Barely survived our peak season. Absolutely brutal this year.

What'd I miss?

 

[L0rdGwyn]

I'm back! Barely survived our peak season. Absolutely brutal this year.

What'd I miss?

Let me sum it up for you.....

Tubes.

 

[heliosphann]

Let me sum it up for you.....

Tubes.

Nooooooooo?!?

 

[carlman14]

Oh, which username is Zachi, or is that his name here? And is he getting a SET amp? I'm interested to finally read any more impressions on one of yours.

Also would you mind to mention how @carlman14 is lookin' in the queue? I was hoping his OTC SET amp may be ready for my Seattle meet the last Saturday of the month.

Just FYI I am getting a GOTL from Glenn, not an OTC SET amp. Glenn mentioned that he has a couple more amps to build, then mine. I don't know how fast he cranks these out, but I'm assuming that mine will not be ready in time for your meet.

 

[GDuss]

Was doing the Tung Sol's earlier this evening. Liked all....but a bit too much treble?

The treble was a bit much, but also vocals were too prominent. The stage was expansive, but it's like the singers are pushed right up on you.

The Ken Rad 12J5GT's are much better with the C3g's. I know @Monsterzero mentioned that going from KR's to the Sylvania's didn't give up much bass for him, but it's been some time since I put in KR tubes (with Sylvania's, RCA's, and Tung Sol's in the meantime). This KR bass is nice. Something about these tubes just makes you want to pay attention to the bass and just follow along with it.

Funny how different tubes make you want to focus on different aspects of the music. Then some tubes just put it all together perfectly and you enjoy it all as a whole picture.

 

[exdmd]

Hi guys, for some reason I'm still not getting notifications from this thread. Meanwhile the rest of the hi-fi community is also starting to glow about the potential of the HEDDphone's new VVT AMT transducer technology with Jude just posting his measurements and its' being on the verge of public release, and I'm getting closer to making the final payment on my OTC SET amp which is largely designed around it.

Has anyone else received or is in line for their SET amps from Glenn?

@2359glenn makes an output transformer coupled SET amp with impedance low enough to drive the 42 Ohm HEDDphones?

 

[DecentLevi]

@2359glenn makes an output transformer coupled SET amp with impedance low enough to drive the 42 Ohm HEDDphones?

Yup he's making me a custom amp with 32 ohms (and 8 ohm switch for speakers) which should be more than enough for the 42 ohm headphones, and I was told the number should be lower than your headphone impefance needs, and with mine I will be able to roll either 2 or 4 output tubes which should also increase the power as needed.... Let @2359glenn fill you in better than I can on the specs

PS - here is more on the specs of the HEDDphone so Glenn can confirm whether your amp is perfectly suitable to drive it:
Impedance of 42 ohms
Sensitivity 87 dB/1mW

 

[exdmd]

Yup he's making me a custom amp with 32 ohms (and 8 ohm switch for speakers) which should be more than enough for the 42 ohm headphones, and I was told the number should be lower than your headphone impefance needs, and with mine I will be able to roll either 2 or 4 output tubes which should also increase the power as needed.... Let @2359glenn fill you in better than I can on the specs

PS - here is more on the specs of the HEDDphone so Glenn can confirm whether your amp is perfectly suitable to drive it:
Impedance of 42 ohms
Sensitivity 87 dB/1mW

Very cool! My Kenzie has a 32 Ohm tap but I thought the rule of 8 applied so output impedance for 42 Ohm phones should be down around 5 Ohms. At least you have 8 Ohms available look forward to your listening impressions.

 

[Zachik]

Oh, which username is Zachi, or is that his name here?

That would be me!!

 

[Silent One]

Keiko Matsui....Japanese keyboardist...wowzers via this tube compliment!



Talk about hearing stuff you never knew was in there...!!

Keiko...Matsui? She. Is. Special. Over the years I’ve had a few of her CDs that never made back into my home (friends!!!). I’ll admit to making exceptions to former roommies. But my long-time reserved music & books policy is enforced - you can enjoy here and it stays here. Currently have under Keiko:

Doll
Dream Walk
Full Moon And The Shrine
Moyo
No Borders
The Ring
Sapphire
Yamaha R&D Session III

If you do not have or have not heard the Yamaha studio recording on vinyl, it is really nice (1981 - Los Angeles). Before marrying Mr.Matsui, Keiko Doi was a 19 year old wonder out of Yamaha Univ working with Jazz greats in LA. On this session she’s giggin’ with Nathan East, Steve Foreman, Yayoi Hirabe & Vince Colaiuta.

 

[L0rdGwyn]

@2359glenn makes an output transformer coupled SET amp with impedance low enough to drive the 42 Ohm HEDDphones?

Glenn uses Lundahl speaker OPTs in his amps. So a 32ohm or 8ohm tap doesn't necessarily reflect the output impedance of the amp, that is just the load the transformer is expecting to see, the output impedance will be lower. You have to take into account the plate resistance of the output tube as well as the transformer specifications (primary and secondary winding resistance), whereas in the Kenzie, they use custom wound headphone output transformers, which likely have a smaller turns ratio than a speaker OPT and results in a higher output impedance.

So the 32ohm tap of @DecentLevi 's amp will have an output impedance of less than 32 ohms. I don't know what tubes he is using, but here is an example.

Take the KT66 as a strapped triode (which I think is on the menu), plate resistance is roughly 1300ohm. Using the Lundahl LL1623 output transformer wired for a 5.6k primary into a 32ohm load, its primary winding DC resistance is 164ohm. So in series with the plate resistance, that is 1464ohm on the primary side (the side the output tube sees). The secondary DC resistance of the LL1623 is 0.4ohm. Wired for 5.6k into 32ohms, it has an impedance transformation ratio of 175:1. So with 1464ohm on the primary, the reflected secondary resistance will be 1464/175 = 8.4ohm. Add in the 0.4ohm resistance of the secondary, you get 8.8ohm. If you want you can also add on the resistance of the headphone cable too.

So, as a rough example, into a 32ohm headphone, you would be getting a 8.8ohm output impedance and a damping factor of 3.6. With a 45ohm load, a damping factor of 5.11.

Doing the same thing for a 5.6k into 8ohm tap would give an output impedance of 2.5ohm. So a 45ohm load connected to the 8ohm tap would give a damping factor of 18.

 

[maxpudding]

Try unsubscribing and resubscribing, that seemed to do the trick for me.

In my case I would try to not exit the forum or close the tab while going through all the posts, because if I did, I won't be getting any notifications either.

So, I would try to read until the end of the thread before closing the tab, or go to the end of the thread to start the notifications again

That seems to be working for me.

 

[cdanguyen08]

It's almost February! 6 months went by quicker than I thought lol