Recommended SET 300B tube amp for Klipschorn speakers

[pnort]

Looking for adequate performance without going to Western Electric 91E expense of $15,000 plus $1000 for 16 ohm transformer

[seti]

You don't need to spend a fortune. I like Min's Tube Audio Lab. He has been building 91A instpired amps for years. Great bang for the buck. I'd trust him over the newly launced WE.

 

http://tubeaudiolab.com/

[Curious_George]

On 1/15/2022 at 6:19 PM, pnort said:

Looking for adequate performance without going to Western Electric 91E expense of $15,000 plus $1000 for 16 ohm transformer

Wha is your budget?

[pnort]

No budget but I’d rather not put a lot of money into the project. I have 1972 Klipschorns that I bought after exchangeing some letters with PWK. Right now I’m scanning old slides. I bought a Vincent pho 700 a few years ago and I’ve listened to it a bit. Seemed wonderful feeding a Denon solid state amp but I’d like to set up a tube amp for digitizing my records. 
I bought a dynaco kit from Bob Latigo but it has some problems and I gave up on it around the time Covid started. I’d built numerous Heathkits and never had a problem so I’m disappointed in myself. 
one comment—PWK had little concern for harmonic distortion because music has natural harmonics. The clarity of Khorns he attributed to the efficiency of horn-loading because it results in linear reproduction which minimizes inter modulation distortion that produces frequencies that are not part of the music.

excuse the long post

[Curious_George]

On 1/17/2022 at 1:01 AM, pnort said:

No budget but I’d rather not put a lot of money into the project. 

 

So, there is a budget in there somewhere...

 

You can spend from $1000 to $5000 on a 300B amp or more. I would stick to the brands that have the better reviews, but audio is so subjective. 

 

One item to consider if your are intent on running your khorns on a single-ended amp is the khorn crossover. From the factory, the khorn impedance varies quite a bit over the audible range. This is usually not good from a single-ended amp point of view. It is not absolutely necessary, but I would consider modifying your factory crossover (to have more of a constant impedance) to compliment your tube amp slection. There is a lot of info here on crossovers for khorns, LaScala's. etc.

 

 

[erik2A3]

13 hours ago, Curious_George said:

ne item to consider if your are intent on running your khorns on a single-ended amp is the khorn crossover. From the factory, the khorn impedance varies quite a bit over the audible range. This is usually not good from a single-ended amp point of view. It is not absolutely necessary, but I would consider modifying your factory crossover (to have more of a constant impedance) to compliment your tube amp slection. There is a lot of info here on crossovers for khorns, LaScala's. etc.

 

Excellent information, and I would add that whether the crossover in his K-horns (which I also owned for years, along with a few pairs of La Scalas), is suitable for single ended 300Bs perhaps depends more on the crossover in question.  The lower order designs, such as the type A and/or AA actually are very suitable for SE 300Bs, 2A3s, 45s, PX4,s, and so on.  It's when the amplifier is forced to contend with higher-order designs, such as the type AL (rather infamous on this forum, but actually sounds quite good with enough power in front of it -- IMO), that lower output amplifiers (eg most single-ended triodes) start to run out of steam -- not so much from wild impedance swings, but rather the insertion losses associated with higher order crossover slopes.  When one's amplifier is able to squeeze out only 1.5 - 8 watts or so, the greater number of passive components required by higher-order crossovers, the more the situation becomes like a 4 cylinder, 2-wheel-drive sedan trying to navigate through deep, soft sand, mud, etc.  In other words, the fewer the number of chokes (aka inductors), capacitors, and resistors (as in fixed or variable L-pads), the more single-ended-amplifier-friendly a crossover tends to be.  And when a network starts adding even greater complexity in the form of resonant peak filters, Zobel equalization networks, and so on, things just get worse.  I've worked with all of those in the past, and what one ends up with, particularly with such tiny amplifier wattage, is a linear response that sounds like a thick felt pad was draped over what would otherwise be crystal clear sound.

 

This is one of the reasons that there are those (and I include myself among them) that really like the sound of very high quality single, full-range drivers that don't use crossovers -- except sometimes for the parts required (or more accurately, desired....I don't care for them) for baffle-step compensation.

 

To the OP:  That's really neat you've corresponded with PWK in the past!  Very special indeed.  We might remember, as well, one of this illustrious gentleman's comments regarding amplifier output.  "What the world needs is a good 5-watt amplifier."  I hope I have that at least mostly correct.

 

I used single ended triodes with our K-horns and La Scalas (and Heresies) alike for decades, and was able to get extremely high, undistorted volume levels from all of them.  However, what's loud to one person might not be the case for someone else; so one can't discount the importance of  listening tastes and priorities.  In general, though, and in my own experience (which is unique to me, as well as some other old timers here who enjoyed the same speakers with low power amplification), I am absolutely comfortable saying it's possible to obtain very, very good sound quality from single-ended amplifiers and Klipschorns.   I would agree that a constant reflected impedance can be beneficial, but I would humbly submit it's most certainly not mandatory.  If it were, Klipsch would have been more aware of that characteristic than we during those earlier years.  I built my own 6db/octave crossovers for my k-horns and la scales, often with a true band-pass for the midrange. Moreover, I found I actually preferred a variable L-pad to the autoformer, the latter of which (just for me, mind you) seemed to sound veiled in comparison.  Moreover, one did not have to change values of input capacitance to the mid-range horn as one does with the changing of taps (in order to attenuate) on the autoformer in order to maintain original crossover frequencies.

 

Despite the fact that (I think) Klipsch is now using another vendor for crossover repairs and upgrades (rather sad and unfortunate in my personal view just in a historic sense as it relates to this forum), I could not give the Crites family http://critesspeakers.com a higher or stronger recommendation for their understanding-of and experience-with Klipsch crossovers.  The same can most certainly said for ALK Engineering, and Dean (although I think he may not be doing crossover work any longer).  All three of the above have spent decades offering upgrades and repairs...and kits...of extraordinarily high quality.

 

I've used my own 300B amplifiers with both the type A and AA networks, and they absolutely sang through the monster heritage horns.  Good luck in your search!

Edited January 19, 2022 by erik2A3
clarity

[henry4841]

On 1/17/2022 at 12:01 AM, pnort said:

 

 

 

26 minutes ago, erik2A3 said:

Excellent information, and I would add that whether the crossover in his K-horns (which I also owned for years, along with a few pairs of La Scalas), is suitable for single ended 300Bs perhaps depends more on the crossover in question.  The lower order designs, such as the type A and/or AA actually are very suitable for SE 300Bs, 2A3s, 45s, PX4,s, and so on.  It's when the amplifier is forced to contend with higher-order designs, such as the type AL (rather infamous on this forum, but actually sounds quite good with enough power in front of it -- IMO), that lower output amplifiers (eg most single-ended triodes) start to run out of steam -- not so much from wild impedance swings, but rather the insertion losses associated with higher order crossover slopes.  When one's amplifier is able to squeeze out only 1.5 - 8 watts or so, the greater number of passive components required by higher-order crossovers, the more the situation becomes like a 4 cylinder, 2-wheel-drive sedan trying to navigate through deep, soft sand, mud, etc.  In other words, the fewer the number of chokes (aka inductors), capacitors, and resistors (as in fixed or variable L-pads), the more single-ended-amplifier-friendly a crossover tends to be.  And when a network starts adding even greater complexity in the form of resonant peak filters, Zobel equalization networks, and so on, things just get worse.  I've worked with all of those in the past, and what one ends up with, particularly with such tiny amplifier wattage, is a linear response that sounds like a thick felt pad was draped over what would otherwise be crystal clear sound.

 

This is one of the reasons that there are those (and I include myself among them) that really like the sound of very high quality single, full-range drivers that don't use crossovers -- except sometimes for the parts required (or more accurately, desired....I don't care for them) for baffle-step compensation.

 

To the OP:  That's really neat you've corresponded with PWK in the past!  Very special indeed.  We might remember, as well, one of this illustrious gentleman's comments regarding amplifier output.  "What the world needs is a good 5-watt amplifier."  I hope I have that at least mostly correct.

 

I used single ended triodes with our K-horns and La Scalas (and Heresies) alike for decades, and was able to get extremely high, undistorted volume levels from all of them.  However, what's loud to one person might not be the case for someone else; so one can't discount the importance of  listening tastes and priorities.  In general, though, and in my own experience (which is unique to me, as well as some other old timers here who enjoyed the same speakers with low power amplification), I am absolutely comfortable saying it's possible to obtain very, very good sound quality from single-ended amplifiers and Klipschorns.   I would agree that a constant reflected impedance can be beneficial, but I would humbly submit it's most certainly not mandatory.  If it were, Klipsch would have been more aware of that characteristic than we during those earlier years.  I built my own 6db/octave crossovers for my k-horns and la scales, often with a true band-pass for the midrange. Moreover, I found I actually preferred a variable L-pad to the autoformer, the latter of which (just for me, mind you) seemed to sound veiled in comparison.  Moreover, one did not have to change values of input capacitance to the mid-range horn as one does with the changing of taps (in order to attenuate) on the autoformer in order to maintain original crossover frequencies.

 

Despite the fact that (I think) Klipsch is now using another vendor for crossover repairs and upgrades (rather sad and unfortunate in my personal view just in a historic sense as it relates to this forum), I could not give the Crites family http://critesspeakers.com a higher or stronger recommendation for their understanding-of and experience-with Klipsch crossovers.  The same can most certainly said for ALK Engineering, and Dean (although I think he may not be doing crossover work any longer).  All three of the above have spent decades offering upgrades and repairs...and kits...of extraordinarily high quality.

 

I've used my own 300B amplifiers with both the type A and AA networks, and they absolutely sang through the monster heritage horns.  Good luck in your search!

I pretty much agree with all you said. 

[captainbeefheart]

Do not be scared away from single ended amps, the issue is most just copy schematics from old designs which don't do so well with tough loads. I agree with the statement that you either modify the crossover to look more like a constant resistance or you purchase and amplifier that can drive the tougher loads.

 

The majority of SET amplifiers do not have feedback, I am not in the camp that is against feedback. It's the internal feedback mechanism that makes triodes so linear, it's not external like adding a resistor from plate to grid. The best part about triode amps is the distortion is already low enough that you don't need a lot of feedback to make them better, you just want to get them to be able to control the woofer. For this I like to add a variable damping control that allows you to sweep between different amounts of both positive and negative current feedback sensed directly from the speaker coil current. Of course you can set the control to zero and use the amp without the feature so you have options from normal mode with the control set to zero all the way to a negative output impedance giving better damping compared to even your average solid state amplifier.

 

Then there are push pull designs if you change your mind. One amp PWK pushed to be used with the K-horn is a Brook 2A3 push pull amplifier, I have made clones of these amps with the 2A3 and a less expensive version that uses a 6AV5GA triode wired which has the same electrical properties and linearity as a 2A3. The difference being the 6AV5GA doesn't require such an elaborate heater/filament supply and the tubes themselves are only $5 each for NOS varieties so you can get excellent performance, same as a 2A3 at a lower price tag.

 

 

[seti]

I am in the anti feedback camp but only because I don't like dealing with it in DIY.  Nothing wrong with it unless you get culty.

 

 

[Curious_George]

2 hours ago, seti said:

I am in the anti feedback camp but only because I don't like dealing with it in DIY.  Nothing wrong with it unless you get culty.

 

 

 

Feedback is great if used correctly, like anything. The modern world we currently know could not exist without feedback in all of its forms. 

 

Now AI (Artificial Intelligence)... forget it. 

[pnort]

I decided to build an Elekit 8600S from TubeDepot. It works! I have some cheaper tubes in it now to test it out on some old Advent speakers. Will hook it up to the Klipschorns soon. Any opinions on whether the new Western Electric 300B tubes are worth the money?

 

[pnort]

Thank you to all who sent some advice!

My only previous tube amp was a Knight 24W mono that I got around 1956. I bought a University model 312 triaxial speaker and built a cabinet based on an electrovoice corner model that had a horn-like opening in the back coming from down low. To test it out, I carried the speaker out into the back yard, ran wires from the amp, dropped the needle on a 78 rpm Elvis record at high volume, and ran upstairs, got on my bike and rode a couple blocks to see how far away I could hear it. When I got back there was only the thump of the needle at the end of the groove and a bunch of neighbors standing around the speaker cabinet not knowing wha to do. I was like 13 or 14. Rock n Roll needed HiFi !

[henry4841]

5 hours ago, pnort said:

I decided to build an Elekit 8600S from TubeDepot. It works! I have some cheaper tubes in it now to test it out on some old Advent speakers. Will hook it up to the Klipschorns soon. Any opinions on whether the new Western Electric 300B tubes are worth the money?

 

Very Nice. I look forward to impressions of sound. 

[grendel23]

11 hours ago, pnort said:

I decided to build an Elekit 8600S from TubeDepot.

I own the same amp with Gold Lion tubes. I use it primarily as a headphone amp. With a pair of LCD-3 phones and a good R2R dac it sounds very good.

[captainbeefheart]

Good choice!!  Glad you're happy!!

[michaelwjones]

On 3/8/2022 at 12:37 AM, pnort said:

Any opinions on whether the new Western Electric 300B tubes are worth the money?

 

 

In a word: absolutely. I've tried multiple brands and had settled on KR Audio until this latest iteration of WE 300B was released. The difference is night and day. There is a reason WE 300Bs are the tube everyone tries to recreate or duplicate. 

 

[pallpoul]

I bought a 300B amp from Dennis Had, I had to convince him to build one, and after he did, he liked it so much, he built a few more and sold them on his eBay store. 

They sound great with any heritage Klipsch speaker, so far i have used mine with my KH 70th anniversary edition, I used a matching preamp by Dennis Had, sound is amazing, dead silent system, and plenty clean power. 

 

 

[jwc]

On 1/19/2022 at 8:16 AM, erik2A3 said:

Excellent information, and I would add that whether the crossover in his K-horns (which I also owned for years, along with a few pairs of La Scalas), is suitable for single ended 300Bs perhaps depends more on the crossover in question.  The lower order designs, such as the type A and/or AA actually are very suitable for SE 300Bs, 2A3s, 45s, PX4,s, and so on.  It's when the amplifier is forced to contend with higher-order designs, such as the type AL (rather infamous on this forum, but actually sounds quite good with enough power in front of it -- IMO), that lower output amplifiers (eg most single-ended triodes) start to run out of steam -- not so much from wild impedance swings, but rather the insertion losses associated with higher order crossover slopes.  When one's amplifier is able to squeeze out only 1.5 - 8 watts or so, the greater number of passive components required by higher-order crossovers, the more the situation becomes like a 4 cylinder, 2-wheel-drive sedan trying to navigate through deep, soft sand, mud, etc.  In other words, the fewer the number of chokes (aka inductors), capacitors, and resistors (as in fixed or variable L-pads), the more single-ended-amplifier-friendly a crossover tends to be.  And when a network starts adding even greater complexity in the form of resonant peak filters, Zobel equalization networks, and so on, things just get worse.  I've worked with all of those in the past, and what one ends up with, particularly with such tiny amplifier wattage, is a linear response that sounds like a thick felt pad was draped over what would otherwise be crystal clear sound.

 

This is one of the reasons that there are those (and I include myself among them) that really like the sound of very high quality single, full-range drivers that don't use crossovers -- except sometimes for the parts required (or more accurately, desired....I don't care for them) for baffle-step compensation.

 

To the OP:  That's really neat you've corresponded with PWK in the past!  Very special indeed.  We might remember, as well, one of this illustrious gentleman's comments regarding amplifier output.  "What the world needs is a good 5-watt amplifier."  I hope I have that at least mostly correct.

 

I used single ended triodes with our K-horns and La Scalas (and Heresies) alike for decades, and was able to get extremely high, undistorted volume levels from all of them.  However, what's loud to one person might not be the case for someone else; so one can't discount the importance of  listening tastes and priorities.  In general, though, and in my own experience (which is unique to me, as well as some other old timers here who enjoyed the same speakers with low power amplification), I am absolutely comfortable saying it's possible to obtain very, very good sound quality from single-ended amplifiers and Klipschorns.   I would agree that a constant reflected impedance can be beneficial, but I would humbly submit it's most certainly not mandatory.  If it were, Klipsch would have been more aware of that characteristic than we during those earlier years.  I built my own 6db/octave crossovers for my k-horns and la scales, often with a true band-pass for the midrange. Moreover, I found I actually preferred a variable L-pad to the autoformer, the latter of which (just for me, mind you) seemed to sound veiled in comparison.  Moreover, one did not have to change values of input capacitance to the mid-range horn as one does with the changing of taps (in order to attenuate) on the autoformer in order to maintain original crossover frequencies.

 

Despite the fact that (I think) Klipsch is now using another vendor for crossover repairs and upgrades (rather sad and unfortunate in my personal view just in a historic sense as it relates to this forum), I could not give the Crites family http://critesspeakers.com a higher or stronger recommendation for their understanding-of and experience-with Klipsch crossovers.  The same can most certainly said for ALK Engineering, and Dean (although I think he may not be doing crossover work any longer).  All three of the above have spent decades offering upgrades and repairs...and kits...of extraordinarily high quality.

 

I've used my own 300B amplifiers with both the type A and AA networks, and they absolutely sang through the monster heritage horns.  Good luck in your search!

Great post.  Agree with a lot of that.

[OO1]

On 3/8/2022 at 1:37 AM, pnort said:

 Any opinions on whether the new Western Electric 300B tubes are worth the money?

 

 

 the Tubes use  New  2021-22 components and materials   ,which show that  it is quite important for the WE 300B , yes , age matters

[Curious_George]

On 3/8/2022 at 1:37 AM, pnort said:

Any opinions on whether the new Western Electric 300B tubes are worth the money?

I've heard yes and no. I would personally like to A/B WE 300B's with a good alternate brand, but I have not had the opportunity. Judging from what I have heard in the past 40 years when comparing amps, tubes, topologies, etc. I'd be surprised that a real WE 300B is that much better than a good alternative. 

 

New modern 2A3's blow away old RCA 2A3's that are selling for stupid money. I have heard the difference with these tubes, which is why I can't believe the 300B would be much different. 

 

But hey, I'm just telling you what my ears hear and I am far from deaf.