The Stax Thread III

[alota]

@leManu Yep, amp upgrade would be the way to go. Your Lambdas will scale surprisingly well. In that price range I'd try to score a used KGST or KGDT (may require some exercise of patience). These will sound sweet with Lambdas.

which amplifier is KGDT?

 

[Chefguru]

Hi you all,

I never was a big headphones listener, but with new life changes, I needed a good pair of headphones. I went to the Montreal audio show to listen to a lot of different models, and I quickly found out that I loved electrostatic. I then went to a store to listen to l500 and l700, and I liked the smoothness of the l500 better. So I recently bought a used pair of l500mk2 with a srm-252s on this site to see if I can adjust to headphone listening. I'm pretty amazed at the sound so far, and I discovered that I love listening to headphone much more than I thought. I use the crinacle convolution filter with Roon that I found on the jaakkopasanen github, which also made the sound more pleasing to me.

But the sound is still several notches below my main speaker setup, so I'll probably go on the upgrade path soon. What should be my upgrade path? I'm thinking about buying a better amp first, so I can eventually get a pair of headphones that requires more power than the l500. I'm I right here? If so, what are the amp I should look at?

Budget around 1-2k for the amp, ideally something I can find second hands.

My source is a Linn streamer.

Thanks for your insight.

KGSSHV is probably the move for 90% of people in your boat because it'll run any HP you choice to upgrade to including hard-to-drive stuff like the 007 and CRBN. It'll sound significantly better than the 252s. Used you can find one for 2k. Look for a Mjolnir (gold standard), Dukei or Soren build. There are other good builders, but those have the A+ reputation of good builds.

That said, the KGST might be a better companion to the L500. It's also a better fit for the 009 and x9k than the kgssHV - but might struggle with the 007 and a few other older headphones that need serious power. KGST is not as commonly built, so this might be closer to $2.5k and out of your price range.

Other options would be a modified SRM-717 (look on Mjolnir-Audio's used amps) which can be had for under 2k and is essentially a KGSS (non-hv). Or a 006T modified which is like a lower-power KGST. Also under 2k.

 

[number1sixerfan]

KGSSHV is probably the move for 90% of people in your boat because it'll run any HP you choice to upgrade to including hard-to-drive stuff like the 007 and CRBN. It'll sound significantly better than the 252s. Used you can find one for 2k. Look for a Mjolnir (gold standard), Dukei or Soren build. There are other good builders, but those have the A+ reputation of good builds.

That said, the KGST might be a better companion to the L500. It's also a better fit for the 009 and x9k than the kgssHV - but might struggle with the 007 and a few other older headphones that need serious power. KGST is not as commonly built, so this might be closer to $2.5k and out of your price range.

Other options would be a modified SRM-717 (look on Mjolnir-Audio's used amps) which can be had for under 2k and is essentially a KGSS (non-hv). Or a 006T modified which is like a lower-power KGST. Also under 2k.

I think you are on of the few people that have heard, and/or have significantly researched many of the good to great stat amps. Should do a thread or something. (although I can't remember if a stat amp specific thread has already been done)

I think between all of the stax amps, the KG/DIY amps, there's not really a wide range of knowledge of all the options. Many see it as Carbon/BHSE or low level stax amp. I know I personally don't have close familiarity of them all either.

Edit: and oh, on my end for the OP, I would just add that the Stax T1s, which can be found for less than $1k, is a pretty solid option. Neutral tonality, decent dynamics and good resolution. A bit softer in bass for the harder to drive stats like the CRBN, 007, etc. but pretty good for the price. I keep mine as a backup.

 

[SolarCetacean]

which amplifier is KGDT?

KGDTs are similar to the KGST, but use two dual triode tubes instead of four single triode tubes (e.g. 2x 6CG7, 6SN7, or ECC99 instead of the 4x 6S4A in the KGST). They are rare, and when I asked spritzer about them in an email conversation, he said he stopped building them because they took nearly as much effort to build as a KGST but demand for them was low.

Really, a KGDT was never much different from a CCS-modded SRM-T1 or 006t. Those amps already use dual triodes (6CG7), and once you switch their resistor loads for CCSes, you get a similar boost in performance that you get from a KGDT. A KGDT would have better power supplies and surrounding circuitry (sort of a souped-up T1), but the core architecture is similar. So spritzer has moved towards selling modded T1/006t amps instead of KGDTs.

@leManu For the <2K budget, I also suggest taking a look at one of the modded SRM-T1/006t amps from Mjolnir Audio (run by the spritzer I mentioned earlier). Those run in the $1000-$1400 range and are probably the best "bang for buck" option that's readily available. Of course, if you can find a used KGST under $2000, I'd go for that, but then you have to play the used market, while Mjolnir Audio has plenty of the modded amps in stock.

 

[alota]

KGDTs are similar to the KGST, but use two dual triode tubes instead of four single triode tubes (e.g. 2x 6CG7, 6SN7, or ECC99 instead of the 4x 6S4A in the KGST). They are rare, and when I asked spritzer about them in an email conversation, he said he stopped building them because they took nearly as much effort to build as a KGST but demand for them was low.

Really, a KGDT was never much different from a CCS-modded SRM-T1 or 006t. Those amps already use dual triodes (6CG7), and once you switch their resistor loads for CCSes, you get a similar boost in performance that you get from a KGDT. A KGDT would have better power supplies and surrounding circuitry (sort of a souped-up T1), but the core architecture is similar. So spritzer has moved towards selling modded T1/006t amps instead of KGDTs.

@leManu For the <2K budget, I also suggest taking a look at one of the modded SRM-T1/006t amps from Mjolnir Audio (run by the spritzer I mentioned earlier). Those run in the $1000-$1400 range and are probably the best "bang for buck" option that's readily available. Of course, if you can find a used KGST under $2000, I'd go for that, but then you have to play the used market, while Mjolnir Audio has plenty of the modded amps in stock.

Thanks. I have my t1 in surgery now for revision and ccs modules

 

[leManu]

Thanks for all the replies. I'm a bit more focused on what and where to buy now. But I'm still confused about some stuff. Can someone explain what are those acronyms (KGSSHV, KGDT, KGST, KGSS, CCS)? I guessed they refer to the amp topology and technology, but what do they really mean and what's the sound difference between them?

 

[ufospls2]

Thanks for all the replies. I'm a bit more focused on what and where to buy now. But I'm still confused about some stuff. Can someone explain what are those acronyms (KGSSHV, KGDT, KGST, KGSS, CCS)? I guessed they refer to the amp topology and technology, but what do they really mean and what's the sound difference between them?

As far as I know (please chime in if I'm wrong)

Kevin Gilmore High Voltage
Kevin Gilmore Dual Triode
Kevin Gilmore Single Triode
Kevin Gilmore Solid State
Constant Current Source

Kevin Gilmore is the designer of the amp circuits, which he provides the plans for to the DIY community.

Dual Triode and Single Triode are types of tube architecture. Solid state means transistor not tube based, High Voltage is a more powerful solid state amp.

KGSSHV Carbon is a misunderstanding or mistranslation (for lack of a better word) of the SiCFet output transistors used in the design. SiliconCarbide (hence misnamed as carbon, from carbide.)

 

[SolarCetacean]

Thanks for all the replies. I'm a bit more focused on what and where to buy now. But I'm still confused about some stuff. Can someone explain what are those acronyms (KGSSHV, KGDT, KGST, KGSS, CCS)? I guessed they refer to the amp topology and technology, but what do they really mean and what's the sound difference between them?

Those are actually just names that were given to the design. They aren't really tech descriptions, but have vague links to their designs. I recall that the "KG" in those names all refer to Kevin Gilmore, the main guy behind those designs.

KGSS: Kevin Gilmore Solid State (amplifier). A classic solid state (non-tube) amplifier design from KG.
KGSSHV: Kevin Gilmore Solid State High Voltage. An improvement over the KGSS, with higher voltages.
KGST: Kevin Gilmore Single Triode. Single triode refers to the type of tubes used in the design. Because in Stax headphones, each channel needs a positive and an inverted negative signal, and single triode tubes only amplify one signal, KGST builds need 4 tubes.
KGDT: Kevin Gilmore Dual Triode. A similar design to the KGST, but using dual triode tubes instead of single triode tubes. These designs only need 2 tubes, as each tube handles two signals simultaneously, so only 1 tube is needed per channel.
CCS: constant current source. It's a circuit that always draws a fixed amount of current. This means that when placed in parallel with another load (e.g. the headphones), the amount of current available to the headphones is more consistent. Because the impedance of electrostatic headphones varies wildly with frequency (due to estats being primarily a capacitive load), using resistors instead of a CCS means that the headphone and resistors basically compete for current, and which one wins depends on the frequency. This is bad for linearity/neutrality. Stax tube amps have historically used resistors to drive the tubes and replacing them with a CCS changes the performance of the amp, generally for the better (though some might prefer the softer, tube-ier sound with the resistors).

 

[ColSaulTigh]

As far as I know (please chime in if I'm wrong)

Kevin Gilmore High Voltage
Kevin Gilmore Dual Triode
Kevin Gilmore Single Triode
Kevin Gilmore Solid State
Constant Current Source

Kevin Gilmore is the designer of the amp circuits, which he provides the plans for to the DIY community.

Dual Triode and Single Triode are types of tube architecture. Solid state means transistor not tube based, High Voltage is a more powerful solid state amp.

KGSSHV Carbon is a misunderstanding or mistranslation (for lack of a better word) of the SiCFet output transistors used in the design. SiliconCarbide (hence misnamed as carbon, from carbide.)

Don't forget KGGG: Kevin Gilmore Grounded Grid

 

[ufospls2]

Don't forget KGGG: Kevin Gilmore Grounded Grid

True, to be clear for others there are quite a few amps I didn't mention, but they weren't mentioned in the original post so I didn't want to confuse things.

 

[timb5881]

I can vouch for Nectar. I have a Pollinator, and I think they sound great.

 

[leManu]

You guys are a great source of answers! I've read that tubes are great for electrostatic headphones, but I never liked tube amps sound. Find them slow and too warm in amplifier for speakers. If it's also the case for headphone amps, I should really be looking for a KGSS or KGSSHV to fit my taste.

But there are a SRM-717 and a SRM-727a for sale here right now. Not mod by spritzer, so not a real KGSS and no CCS or HV, but I'm wondering if it's a good fit and future proof. Can spritzer mod it eventually if I need to? Is using a voltage transformer with those a big deal? What are you thoughts on those?

 

[Chefguru]

You guys are a great source of answers! I've read that tubes are great for electrostatic headphones, but I never liked tube amps sound. Find them slow and too warm in amplifier for speakers. If it's also the case for headphone amps, I should really be looking for a KGSS or KGSSHV to fit my taste.

But there are a SRM-717 and a SRM-727a for sale here right now. Not mod by spritzer, so not a real KGSS and no CCS or HV, but I'm wondering if it's a good fit and future proof. Can spritzer mod it eventually if I need to? Is using a voltage transformer with those a big deal? What are you thoughts on those?

The 717 is older but superior to the 727a. Neither in stock is very good. Spritzer does not do the mod for people - rather he invented the change and he just sometimes does it to used units he has and puts them for sale. If you’re crafty you can maybe do it yourself.

Electrostatic headphones can run tubes natively instead of using a step down , so unlike with dynamic equipment it doesn’t typically color the sound. The KGST is also a hybrid tube amp (tube & SS) so it doesn’t really display the harmonic properties you’re describing.

 

[Chefguru]

Don't forget KGGG: Kevin Gilmore Grounded Grid

It’s out of his price range.

I think your signature is getting too long for us mobile folk…

 

[oneguy]

It’s out of his price range.

I think your signature is getting too long for us mobile folk…

You just need a bigger phone