[cAsE sEnSiTiVe]

@cAsE sEnSiTiVe Is the “feet removal” on the HSA-1b another mod to improve sound or something unique to your use case?

A little bit of both I suppose. I use EVP isolation footers on all my gear, which require fairly precise leveling to properly load them...which can be difficult when the weight distribution of a particular component is not exactly uniform due to heavy power transformers sometimes being off-center within the build. So in my case, the removal of the feet allowed me more surface area in which to find the "sweet spot" to properly level the amp on the footers.

I wrote Danny to make sure the screws for the OEM feet weren't screwed into any nuts that would become loose once I backed out the screw ad removed the feet. He confirmed that the threaded inserts are part of the chassis. So I went full steam ahead.

P.S. Your positive experience with removal of those bottom caps has me thinking of trying that. Thanks for the post.

 

[SageM]

TL;DR; Yes. Removing the bypass capacitors on the HSA-1b sounds better than keeping them in.

In my opinion, HSA-1b should be sold without the bypass capacitors. The mod has rekindled my love for the HSA1b. It feels like a new amplifier.

Better in what way?

• Treble: I listen to field recordings. Most of them with birds. There are certain recordings that used to make me lower the volume to avoid wincing from high pitched sounds piercing my ears. That is resolved with this modification.
• Bass: Music, especially of the electronic variety, often has deep bass that failed to get me bopping using the original HSA-1b. With the mod, my feet and head are bouncing to the rhythm.
• Singer size: The combination of the above allows me to play louder. This in turn lets me set the volume so that the perceived size of the singer is more correct.
• New discoveries: I discovered new sounds. This could be as simple as me playing louder now.
• Bit perfect: I have now turned off convolution filters and bass shelves in Roon.

Any downsides?

• While it is cool to be able to break out one’s soldering iron to do this mod, it’s more awkward than flipping a switch.
• It’s possible that I lost some degree of treble information and soundstage depth. I’d need an unmodified HSA1a and an extra SR1a to be able to test this. Even if that’s the case, for me, this would be the correct trade off. What makes me suspect that could be the case is PS Audio talking about why bypass capacitors are added. See this video at 3:30 and onwards

As much as I like this mod, I’m still lusting for the sound of the VM1a. It offered even more three dimensional body and bass slam. Out of the amplification options I have heard, I’d rank their sound quality as:

1. VM1a
2. HSA1b modded
3. HSA1b original
4. Jotunheim R

Note that I only care about the performance on the SR1a, not the ’cupped’ CA1a version. I’m looking forward to hearing a Star-8 cable to complete the recommendation @SageM offered.

That Raal-Requisite offers tips like this is extraordinary. Thank you!

TL;DR; Yes. Removing the bypass capacitors on the HSA-1b sounds better than keeping them in.

In my opinion, HSA-1b should be sold without the bypass capacitors. The mod has rekindled my love for the HSA1b. It feels like a new amplifier.

Better in what way?

• Treble: I listen to field recordings. Most of them with birds. There are certain recordings that used to make me lower the volume to avoid wincing from high pitched sounds piercing my ears. That is resolved with this modification.
• Bass: Music, especially of the electronic variety, often has deep bass that failed to get me bopping using the original HSA-1b. With the mod, my feet and head are bouncing to the rhythm.
• Singer size: The combination of the above allows me to play louder. This in turn lets me set the volume so that the perceived size of the singer is more correct.
• New discoveries: I discovered new sounds. This could be as simple as me playing louder now.
• Bit perfect: I have now turned off convolution filters and bass shelves in Roon.

Any downsides?

• While it is cool to be able to break out one’s soldering iron to do this mod, it’s more awkward than flipping a switch.
• It’s possible that I lost some degree of treble information and soundstage depth. I’d need an unmodified HSA1a and an extra SR1a to be able to test this. Even if that’s the case, for me, this would be the correct trade off. What makes me suspect that could be the case is PS Audio talking about why bypass capacitors are added. See this video at 3:30 and onwards

As much as I like this mod, I’m still lusting for the sound of the VM1a. It offered even more three dimensional body and bass slam. Out of the amplification options I have heard, I’d rank their sound quality as:

1. VM1a
2. HSA1b modded
3. HSA1b original
4. Jotunheim R

Note that I only care about the performance on the SR1a, not the ’cupped’ CA1a version. I’m looking forward to hearing a Star-8 cable to complete the recommendation @SageM offered.

That Raal-Requisite offers tips like this is extraordinary. Thank you!

I'm really happy that this mod has been helpful to those who have tried it. Thank you.

 

[SageM]

A little bit of both I suppose. I use EVP isolation footers on all my gear, which require fairly precise leveling to properly load them...which can be difficult when the weight distribution of a particular component is not exactly uniform due to heavy power transformers sometimes being off-center within the build. So in my case, the removal of the feet allowed me more surface area in which to find the "sweet spot" to properly level the amp on the footers.

I wrote Danny to make sure the screws for the OEM feet weren't screwed into any nuts that would become loose once I backed out the screw ad removed the feet. He confirmed that the threaded inserts are part of the chassis. So I went full steam ahead.

P.S. Your positive experience with removal of those bottom caps has me thinking of trying that. Thanks for the post.

Glad you asked! I can only imagine what might have been, if metal nuts were rolling around inside!

 

[Failed Engineer]

I picked up a few cable sets on the forum (Star 67, SR728, and Deluxe) and have swapped the Star67 for the SR2 cable on the CA1a and haven't A-Bed yet, but initial impressions (from a generally cable skeptic) are that the Star67 exhibits less of a slight grain that introduces listening fatigue for me after a hour through the HSA1b when I used it with the SR2. It is very smooth but not at the expense of micro dynamic gradations.

I'm enjoying the Star67. At an absolute minimum I can state that this cable allows me to have multi-hour listening sessions which I was previously not able to but that likely understating the impact. I'll A-B a bit over time and imagine the differences will be more evident. The last thing is that the ergonomics of the upgraded cables is far better. The sleeving on the SR2 is stubbornly apt to return to the resting position it wants to be at, not where the listener wants it. No such issues with any of the upgraded cables.

 

[rlawry]

One thing that has continually interested me after reading all 405 pages of the RAAL thread is the issue surrounding bass response, or more precisely, the lack of bass weight, dynamics, and extension. Mind you, I am not complaining about the bass quantity as I feel the bass quality more than makes up for lack of quantity not to mention all the aspects of sound the SR-1b produces in a superior way. So here is my point.

There are ways to fill in this "missing bass content", many of which are relatively simple and inexpensive. First, some SR-1a/b owners have experimented with the use of subwoofers to augment bass response. Of course, there are problems with this approach in that virtually no subwoofer can respond in the same way as a headphone ribbon driver, leading to phase anomalies between headphone and subwoofer, i.e. the bass response lags that of the headphones and gives the impression of a subwoofer booming away as a separate entity. There are numerous traditional subwoofers on the market and also a different type, the Rotary Woofer, www.rotarywoofer.com.

Another way is to employ a bass radiating transducer similar to those used in movie theaters, one of which is the Buttkicker, www.thebuttkicker.com. This thing is referred to as a haptic transducer and I remember well while in high school movie theaters used similar transducers named SenseArround to produce low frequency effects in movies such as The Towering Inferno, Earthquake, and Midway. I remember liking this effect but when you think of it, such effects are more pertinent to rumbling effects and not music pitch and definition. I am not aware that audiophiles, and headphone enthusiasts in particular, employ these haptic low frequency generators on their chairs or couches in any reasonable numbers.

A third and perhaps more effective way to fill in the missing bottom bass octave, is the use of a Subpac unit similar to those used in military training, www.subpac.com. This wearable unit stimulates our skin proprioceptors in a way similar to that of a bass pressure wave generated by a subwoofer. Supposedly they are much more responsive to bass demands and may be able to largely keep up with headphone response. They can connect electronically to an amplifier or to the wifi network in your home. Earlier versions have been long sold out but there is a new version slated for release late this year and beyond. I pre-ordered one that will hopefully arrive by that time. I am not sure how effective it will be but it will interesting to find out.

BTW, I am in no way affiliated with any company making sub-bass devices but someone always looking for an enhanced musical experience. I just thought the group might be interested in such technologies.

 

[ThanatosVI]

One thing that has continually interested me after reading all 405 pages of the RAAL thread is the issue surrounding bass response, or more precisely, the lack of bass weight, dynamics, and extension. Mind you, I am not complaining about the bass quantity as I feel the bass quality more than makes up for lack of quantity not to mention all the aspects of sound the SR-1b produces in a superior way. So here is my point.

There are ways to fill in this "missing bass content", many of which are relatively simple and inexpensive. First, some SR-1a/b owners have experimented with the use of subwoofers to augment bass response. Of course, there are problems with this approach in that virtually no subwoofer can respond in the same way as a headphone ribbon driver, leading to phase anomalies between headphone and subwoofer, i.e. the bass response lags that of the headphones and gives the impression of a subwoofer booming away as a separate entity. There are numerous traditional subwoofers on the market and also a different type, the Rotary Woofer, www.rotarywoofer.com.

Another way is to employ a bass radiating transducer similar to those used in movie theaters, one of which is the Buttkicker, www.thebuttkicker.com. This thing is referred to as a haptic transducer and I remember well while in high school movie theaters used similar transducers named SenseArround to produce low frequency effects in movies such as The Towering Inferno, Earthquake, and Midway. I remember liking this effect but when you think of it, such effects are more pertinent to rumbling effects and not music pitch and definition. I am not aware that audiophiles, and headphone enthusiasts in particular, employ these haptic low frequency generators on their chairs or couches in any reasonable numbers.

A third and perhaps more effective way to fill in the missing bottom bass octave, is the use of a Subpac unit similar to those used in military training, www.subpac.com. This wearable unit stimulates our skin proprioceptors in a way similar to that of a bass pressure wave generated by a subwoofer. Supposedly they are much more responsive to bass demands and may be able to largely keep up with headphone response. They can connect electronically to an amplifier or to the wifi network in your home. Earlier versions have been long sold out but there is a new version slated for release late this year and beyond. I pre-ordered one that will hopefully arrive by that time. I am not sure how effective it will be but it will interesting to find out.

BTW, I am in no way affiliated with any company making sub-bass devices but someone always looking for an enhanced musical experience. I just thought the group might be interested in such technologies.

While interesting ideas, none of those solve the actual "problem"

Except for maybe the subwoofer, but in that case you can use speakers anyway.

If I understood it correctly, all these other devices are meant to make you feel and experience the bass. Most of these sensations usually are only there on louder volumes anyway. Wouldn't such an experience coupled with the missing auditory sensation result in something that feels just off?

 

[rlawry]

While interesting ideas, none of those solve the actual "problem"

Except for maybe the subwoofer, but in that case you can use speakers anyway.

If I understood it correctly, all these other devices are meant to make you feel and experience the bass. Most of these sensations usually are only there on louder volumes anyway. Wouldn't such an experience coupled with the missing auditory sensation result in something that feels just off?

@Thanatos: I am not sure what the actual Subpac low frequency effects are and how well they could lead to a sense of bass pitch, definition, and speed. One of the problems I forgot to mention with a subwoofer is that sounds would be partly muffled when wearing headphones but with the SR-1b the bass attenuation would most likely be less than with headphones or IEMs that seal your ear canal. According the Subpac website there is much more of a pitch definition in bass regions and if so there would be more than just the sensation of bass pressure, which of course how conventional headphones produce bass using what is really a midrange driver. The bass in a sealed system is largely a pressurization-depressurization effect. When I get my Subpac I will report its effects. I would imagine that at least it would produce the sub 30Hz region lacking in the SR-1a/b and whose waves in air are largely omindirectional and therefore hard for the ear to localize its sounds.

 

[Jon L]

Sad day for my Raal SR1a journey.

After careful tuning of system/cabling/source/tweaks, I now am getting SQ out of my SR1a that I do not want to change or improve upon.

My dilemma is that I only truly love the sound of SR1a (and AKG K1000 long ago) only with wings closed basically all the way, limited by physical earlobes.
The razor-sharp edges of the metal grill barely touches my earlobes, but even then, the edges irritate my earlobes quite a bit, especially after long sessions.
If I open the wings enough not to make any physical contact, I do not love the sound over my Abyss 1266 Phi TC or Stax SR009.

Is there a way to take off the inside metal grill or replace it with something that does not have sharp edges? Anyone tried some other method?

 

[RickyV]

TL;DR; Yes. Removing the bypass capacitors on the HSA-1b sounds better than keeping them in.

In my opinion, HSA-1b should be sold without the bypass capacitors. The mod has rekindled my love for the HSA1b. It feels like a new amplifier.

Better in what way?

• Treble: I listen to field recordings. Most of them with birds. There are certain recordings that used to make me lower the volume to avoid wincing from high pitched sounds piercing my ears. That is resolved with this modification.
• Bass: Music, especially of the electronic variety, often has deep bass that failed to get me bopping using the original HSA-1b. With the mod, my feet and head are bouncing to the rhythm.
• Singer size: The combination of the above allows me to play louder. This in turn lets me set the volume so that the perceived size of the singer is more correct.
• New discoveries: I discovered new sounds. This could be as simple as me playing louder now.
• Bit perfect: I have now turned off convolution filters and bass shelves in Roon.

Any downsides?

• While it is cool to be able to break out one’s soldering iron to do this mod, it’s more awkward than flipping a switch.
• It’s possible that I lost some degree of treble information and soundstage depth. I’d need an unmodified HSA1a and an extra SR1a to be able to test this. Even if that’s the case, for me, this would be the correct trade off. What makes me suspect that could be the case is PS Audio talking about why bypass capacitors are added. See this video at 3:30 and onwards

As much as I like this mod, I’m still lusting for the sound of the VM1a. It offered even more three dimensional body and bass slam. Out of the amplification options I have heard, I’d rank their sound quality as:

1. VM1a
2. HSA1b modded
3. HSA1b original
4. Jotunheim R

Note that I only care about the performance on the SR1a, not the ’cupped’ CA1a version. I’m looking forward to hearing a Star-8 cable to complete the recommendation @SageM offered.

That Raal-Requisite offers tips like this is extraordinary. Thank you!

In the future my plan is to do this mod too on the VM-1a. But I would like to replace them with V-cap odam or Duelund caps.

 

[SteveHulk]

@Jon L

You might try:

1/ lie/sit with the back of your head on a soft surface or pillow, that might help to partially close the baffle

2/ put a spacer between your head and the ear pads to push the earpieces slightly further out so you can close the angle without hitting your ears

3/ use a very thin layer of light cloth such as muslin or cheesecloth between the earpieces and your ears

4/ make an addition or extension attached to the baffle to create a partial enclosure

5/ carve foam blocks into a shape that can be worn under the earpieces to create a partial enclosure

Maybe one of these would work. My first try would be number 2.

 

[carboncopy]

In the future my plan is to do this mod too on the VM-1a. But I would like to replace them with V-cap odam or Duelund caps.

Do you think the VM-1a has the same bypass capacitors? It is a rather different circuit...

 

[RickyV]

Do you think the VM-1a has the same bypass capacitors? It is a rather different circuit...

I don’t know but I think the VM uses different caps. But because amplifiers are build to a price point so one can usually improve up on these things.

 

[mimaximax]

One thing that has continually interested me after reading all 405 pages of the RAAL thread is the issue surrounding bass response, or more precisely, the lack of bass weight, dynamics, and extension. Mind you, I am not complaining about the bass quantity as I feel the bass quality more than makes up for lack of quantity not to mention all the aspects of sound the SR-1b produces in a superior way. So here is my point.

There are ways to fill in this "missing bass content", many of which are relatively simple and inexpensive. First, some SR-1a/b owners have experimented with the use of subwoofers to augment bass response. Of course, there are problems with this approach in that virtually no subwoofer can respond in the same way as a headphone ribbon driver, leading to phase anomalies between headphone and subwoofer, i.e. the bass response lags that of the headphones and gives the impression of a subwoofer booming away as a separate entity. There are numerous traditional subwoofers on the market and also a different type, the Rotary Woofer, www.rotarywoofer.com.

Another way is to employ a bass radiating transducer similar to those used in movie theaters, one of which is the Buttkicker, www.thebuttkicker.com. This thing is referred to as a haptic transducer and I remember well while in high school movie theaters used similar transducers named SenseArround to produce low frequency effects in movies such as The Towering Inferno, Earthquake, and Midway. I remember liking this effect but when you think of it, such effects are more pertinent to rumbling effects and not music pitch and definition. I am not aware that audiophiles, and headphone enthusiasts in particular, employ these haptic low frequency generators on their chairs or couches in any reasonable numbers.

A third and perhaps more effective way to fill in the missing bottom bass octave, is the use of a Subpac unit similar to those used in military training, www.subpac.com. This wearable unit stimulates our skin proprioceptors in a way similar to that of a bass pressure wave generated by a subwoofer. Supposedly they are much more responsive to bass demands and may be able to largely keep up with headphone response. They can connect electronically to an amplifier or to the wifi network in your home. Earlier versions have been long sold out but there is a new version slated for release late this year and beyond. I pre-ordered one that will hopefully arrive by that time. I am not sure how effective it will be but it will interesting to find out.

BTW, I am in no way affiliated with any company making sub-bass devices but someone always looking for an enhanced musical experience. I just thought the group might be interested in such technologies.

I do not feel like my sub is booming away by itself. It feels cohesive.

Isn't the subpac just a bass transducer in a backpack?

 

[LucyWu]

Below with added quote!

 

[LucyWu]

I don’t know but I think the VM uses different caps. But because amplifiers are build to a price point so one can usually improve up on these things.

It's also worth observing that amplifiers are built with specific components to meet a specific circuit characteristic. It doesn't take much to turn a lovely amp into an expensive oscillator