[Monsterzero]

Yeah the K240 sextetts, which in my book are the king of vintage cans were 600 ohms. The K340 was 400-480 ohms depending upon which site you read. The Sennheiser HD250 came in two versions, 300 and 600 ohms. then there is the Sennheiser HD424 which clocked in at 2000 ohms.

Cheap headphones back in the day will be of the low impedance variety. For more info on why high impedance was the preferred method and to a certain extent still holds true today check this article

https://www.headphonesty.com/2019/04/headphone-impedance-demystified/

 

[Lvivske]

I AM wondering if it would be worth my while to use a dedicated headphone amp ... although I was expecting it would be more of a want than a need as the amp sounds good and has no issues. The reason I ask is, an audio engineer told me a dedicated headphone amp would knock my socks off sounding so much better, and yet I have no complaints and rather doubt the difference would be that dramatic.

I know my 1975 vintage amp is in good condition and working to spec. ... at least so far. It is, of course, getting older every day, so I suspect it will reach a point where it will need caps and other updates. (Knocking on wood as he typed.)

Having been in this same spot (years ago), I feel like it's a coin toss. The amp I had (well, still have) many years ago was old and hifi internet told me to upgrade to a dedicated headphone amp. I got the amp, found it shrill, and it ended up in a box for the next decade. I preferred the vintage amp.

That said, while I preferred it despite its flaws, and it 'sounded good' to me and functioned....I had no frame of reference of how rough it was until I started upgrading again and got a headphone setup that sounded better. Then I thought dedicated was the way to go....until I restored the original vintage amp, and doing that completely changed it for the better.

With hifi, ignorance is bliss, and things may sound great until you finally hear something better and your standards suddenly change - and there's no going back lol

so your mileage may vary, it depends how much money you throw at things - a lot of dedicated headphone amps sounds great, but its not a guarantee to be better, or to your tastes. At 50 years old, though, I can't see your Sansui's capacitors performing adequately that past shelf life, even if its functioning. In that respect a dedicated amp may be a worthwhile upgrade, but so could restoration, it depends on $$$ and options.

 

[TTmaven]

so your mileage may vary, it depends how much money you throw at things - a lot of dedicated headphone amps sounds great, but its not a guarantee to be better, or to your tastes. At 50 years old, though, I can't see your Sansui's capacitors performing adequately that past shelf life, even if its functioning. In that respect a dedicated amp may be a worthwhile upgrade, but so could restoration, it depends on $$$ and options.

YES - Thank you for this particular reply - because you clearly define the dilemma and obviously "get" what I am coming from. I suppose I should just peel a few bucks form my wad and try a headphone amp and see for myself. I appreciate I am not alone with my dilemma. Money is no object, as I am a retired professional something or other, but I hate wasting money on stuff that does not get the click because that erodes and depletes my equipment fund and, especially, my good bourbon fund.

If I spring for a headphone amp ... any reason I should avoid the JDS Labs Objective2 or Atom +, or possibly the SMSL SH-6, or maybe Shiit Magni1 ? These seem to be fairly well accepted entry level units that provide relatively high performance at a relatively low cost. Are there any other units I should consider as a proper starting point?

Sidebar Footnote -- I fully appreciate and do not dispute your point about restoring my older amp. I have had it checked and verified by a local shop, and I am a serious amateur radio operator who enjoys building gear from scratch, so I continually monitor its status. Parenthetically, I have published a couple published a couple audio and antenna circuit designs in trade magazines and a couple of my antenna ideas were adopted by a German antenna manufacturer. Without being contradictory, you can rest assured I take your point seriously. And, I continuously compare it to several newer, more modern receivers I also own, and it does keep up ... at least so far, anyway! But you are correct - 'dem caps could leak and pop at any time!

Thanks for the uptake - that latest missive puts us on the same page. Unfortunately, ... as you say ... it depends. So maybe I will just try one and know for myself. Happy trails to you. TTmaven

 

[SpeakerBox]

Most of the headphones I have tried on my vintage HK330A via the HP jack sound great (note it is driven by the main amp through a 150 ohm or so dropping resistor). The HD600 on the other hand sound awful via the HP jack. Dead and lifeless. I moved them to the speaker taps and the sound is magnificent.

 

[Lvivske]

YES - Thank you for this particular reply - because you clearly define the dilemma and obviously "get" what I am coming from. I suppose I should just peel a few bucks form my wad and try a headphone amp and see for myself. I appreciate I am not alone with my dilemma. Money is no object, as I am a retired professional something or other, but I hate wasting money on stuff that does not get the click because that erodes and depletes my equipment fund and, especially, my good bourbon fund.

If I spring for a headphone amp ... any reason I should avoid the JDS Labs Objective2 or Atom +, or possibly the SMSL SH-6, or maybe Shiit Magni1 ? These seem to be fairly well accepted entry level units that provide relatively high performance at a relatively low cost. Are there any other units I should consider as a proper starting point?

Sidebar Footnote -- I fully appreciate and do not dispute your point about restoring my older amp. I have had it checked and verified by a local shop, and I am a serious amateur radio operator who enjoys building gear from scratch, so I continually monitor its status. Parenthetically, I have published a couple published a couple audio and antenna circuit designs in trade magazines and a couple of my antenna ideas were adopted by a German antenna manufacturer. Without being contradictory, you can rest assured I take your point seriously. And, I continuously compare it to several newer, more modern receivers I also own, and it does keep up ... at least so far, anyway! But you are correct - 'dem caps could leak and pop at any time!

Thanks for the uptake - that latest missive puts us on the same page. Unfortunately, ... as you say ... it depends. So maybe I will just try one and know for myself. Happy trails to you. TTmaven

I dont really have a strong opinion on entry level headphone amps, all of those get recommended in discussions. I like Schiit as a brand but if I were in that position I'd go with whichever has the simplest return policy (ie from Amazon?) just in case. Whichever you go with, I'd love to hear how it compares!

I dont doubt the Sansui keeps up or has its own signature sound that's comfortable, just that it likely has a lot more potential were it restored since capacitors do have a shelf life even without leaking or outright failing.

 

[kid vic]

Personally, I like running lower-impedance headphones straight off of the speaker taps. I have had excellent results running my HE500s and Focal Clears off of the speaker taps of my Kenwood KA-9100. But it doesn't work for all headphones; my HE1000, HD800, and LCD3 sound much better out of the headphone jack of my Scott 299D. The only headphones that I really like out of the headphone jack of my KA-9100 is my TH600 and that is in no small part due to the fact that I am a bass head (you have never heard bass until you hear a Fostex biocellulose with a severe impedance mismatch).

 

[VinMAC]

Personally, I like running lower-impedance headphones straight off of the speaker taps. I have had excellent results running my HE500s and Focal Clears off of the speaker taps of my Kenwood KA-9100. But it doesn't work for all headphones; my HE1000, HD800, and LCD3 sound much better out of the headphone jack of my Scott 299D. The only headphones that I really like out of the headphone jack of my KA-9100 is my TH600 and that is in no small part due to the fact that I am a bass head (you have never heard bass until you hear a Fostex biocellulose with a severe impedance mismatch).

I have also been able to get very good results with my low impedance headphones Grado GS 1000i, Ultrasone Signature Master and even Meze Elite (all have 32 ohms) and it sounds fantastic even with tube amps. I have read that connecting a 32 ohm headphone to an 8 ohm speaker terminal is ideal and you even get a better damping factor.

An important contribution to this solution is my Speaker Control Box B-Tech BT 911 with almost no loss of sound and with a resistor to protect the headphones.

 

[VinMAC]

Since the topic of connecting low impedance headphones to speaker amplifiers has been on my mind for years, because I have always wondered if this combination is really ideal, or if it does result in an impedance mismatch and thus a loss of sound, I recently received the following response from an audio transformer expert regarding my question about connecting a 32 ohm headphone to an 8 ohm speaker connection via my Speaker Control Box, which gave me great encouragement:

"You can actually use a 32 ohm headphone perfectly on an 8 ohm output, you
even achieve a better damping factor.

Matching impedance between tube and transformer is of course very
important in tube amplifiers that drive speakers because a maximum power
transfer is almost always desirable given the limited power of the
amplifier and limited efficiency of the speaker. This is generally not
an issue with headphones, as the power of the amp is almost always much
more than sufficient.

But you can also consider connecting a resistor (10-12 Ohms) in parallel
to load the amp correctly, but for a different reason than maximum power
transfer.

A property of an underloaded system is that it becomes resonant and
leads to a peak in the high -frequency response, often at a frequency
above our hearing, but this also can influences sound quality.
You can compare it with moving coil phono cartridge that is terminated
with a too high resistance.

It is best to decide subjectively with a listening test whether or not a
parallel resistive termination contributes positively to the sound."

 

[kid vic]

Tube amp crew, is have a question for you all.
Recently my 299D has been making crackling sounds whenever there is heavy bass in music ("Alright" by D'Angelo for instance) and im wondering if thats a sign that my tubes are dying or something else. Also, the bass is noticably weaker than it used to be.
Appreciate all help!

 

[Monsterzero]

Tube amp crew, is have a question for you all.
Recently my 299D has been making crackling sounds whenever there is heavy bass in music ("Alright" by D'Angelo for instance) and im wondering if thats a sign that my tubes are dying or something else. Also, the bass is noticably weaker than it used to be.
Appreciate all help!

Is this a speaker amp or? Do you have other speakers/headphones to test?

To narrow down the cause you need to do a process of elimination. It could be a blown driver on a speaker or headphone. It might be hair on a headphone driver. It could be dirty tube pins/sockets. It could be an amp issue.

If you have spare tubes try those and see if the issue persists.
Try different headphones/speakers. Examine the pins on the tubes. Are they shiny or dull oxidized gray? When was the last time you cleaned the sockets?

 

[TTmaven]

Tube amp crew, is have a question for you all.
Recently my 299D has been making crackling sounds whenever there is heavy bass in music

Um ... ahem ... are referring to a VPI 299D Vacuum Tube Integrated Amplifier, or perhaps an old Scott 220D amplifier ??

If so, perhaps you are over driving its input stage with a very strong signal. I sometimes hear the type of cracking sound you describe when the output from a preamp or line-in source device is too strong or too much for the input of the power amplifier or the input of the next device in a line of connected devices.

No guarantees ... just a suggestion what you might look for. Good luck. TTmaven

​

 

[kid vic]

Is this a speaker amp or? Do you have other speakers/headphones to test?

To narrow down the cause you need to do a process of elimination. It could be a blown driver on a speaker or headphone. It might be hair on a headphone driver. It could be dirty tube pins/sockets. It could be an amp issue.

If you have spare tubes try those and see if the issue persists.
Try different headphones/speakers. Examine the pins on the tubes. Are they shiny or dull oxidized gray? When was the last time you cleaned the sockets?

It persists across headphones so not from there.

I don't have spare tubes and I have never cleaned the sockets; I bought it used so I think that that is a likely culprit.

Thanks

 

[kid vic]

Um ... ahem ... are referring to a VPI 299D Vacuum Tube Integrated Amplifier, or perhaps an old Scott 220D amplifier ??

If so, perhaps you are over driving its input stage with a very strong signal. I sometimes hear the type of cracking sound you describe when the output from a preamp or line-in source device is too strong or too much for the input of the power amplifier or the input of the next device in a line of connected devices.

No guarantees ... just a suggestion what you might look for. Good luck. TTmaven

​

I'm referring to the old Scott 299D that the VPI was based on.

Interesting, I have noticed it when I stream through my Musician Audio Pegasus but I can't recall if it happens when I play records so I'll try that out.

Thanks

 

[kid vic]

@TTmaven looks like you were on the right track. I checked and my 299D was plugged into the XLR outputs (3.55 vrms) so I switched to the RCA outputs (2.2 vrms) and the crackling was massively improved. I listened to my Gold note PH10 and I didn't hear any crackling so I think that was the culprit. So I think it was clipping not crackling that I was hearing.

I still want to try cleaning the pins and sockets like @Monsterzero mentioned. Any videos and tips?

Thanks to both of you!

 

[Monsterzero]

Any videos and tips?

Pipe cleaner and rubbing alcohol.

Unplug amp from wall socket first.

Dip pipe cleaner into bottle of alcohol, shake off excess fluid, stick pipe cleaner into every pin hole, up and down a few times. move to to next socket, rinse repeat.

If you've never cleaned them you most likely will see a lot of black grime on the pipe cleaner.

Some videos will tell you to use Deoxit instead of alcohol. I have used that myself with no issues, but Deoxit can leave aome gunk in there that is hard to remove, so proceed with caution.

After all the pin holes have been cleaned, leave ample time (over night) before re-inserting tubes and firing amp back up.