The OTL i heard was an Atma Sphere M60 that uses a really small amount of feedback. I really liked it. I tend to like amps that dont use a lot or no feedback hence me being curious about DHTs. While i respect high voltage or any voltage really, dont think i want something w that high (1kv +) voltage in the house either. Maybe ill just play around w some 300B or something. In the meantime ill just listening to all the First Watt build ive done
Yup, very well aware of the benefits of pp amps for efficiency and had a line of mods for Dynaco ST-70 and MKIII from 1988 until around 2001. I also manufactured pp 300B and 6550/KT88 amps of up to 120W per channel.
I actually prefer SE and have several of them, no PP at all at this point. I’m not very interested in most of what has been done before and exploring and designing stuff that provides intellectual challenge and has engineering entertainment value is all I am interested in. In my professional work precedent, cost and schedule take precedence over clever, entertaining, and original. I get the passion and excitement from doing my own thing. I recognize that there is nothing truly new in most of what I do, but taking the path well traveled assures I learn little that is new.
It really depends on the design of the amp itself what voltage the main +HT supply is at; as an example, I have an article from an ETI (Electronics Today International) magazine that was published in about 1980, it was for the ETI Project 456 140W Valve Amplifier that used a 12AX7, a 12AU7, and four 6CA7/EL34 Valves, it ran the four 6CA7/EL34 Valves at +750V DC anode/plate voltage, and +400V DC screen voltage with a bias supply of -63V maximum.
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Hi DrNomis44,
Very VTL like design then. High B+, low cathode current (= high impedance). Different winding ratio in the output transformers. I had subscribed to ETI magazine as well.
That works, but at the cost of the very high B+ and associated cost of the power supply parts. For high power, you are way further ahead with solid state.
Hi Kevin,
Exactly, personal preference. Intellectual curiosity is probably the best reason to study and experiment. Most people don't have the freedom to do this, and you're very lucky you have. Time, always the problem.
Very VTL like design then. High B+, low cathode current (= high impedance). Different winding ratio in the output transformers. I had subscribed to ETI magazine as well.
That works, but at the cost of the very high B+ and associated cost of the power supply parts. For high power, you are way further ahead with solid state.
Hi Kevin,
Exactly, personal preference. Intellectual curiosity is probably the best reason to study and experiment. Most people don't have the freedom to do this, and you're very lucky you have. Time, always the problem.
Hi Blk Dynamite,
Whatever you like is a valid choice.
Over my entire career, I have seen a strong correlation between what most people prefer and low distortion. I'm not talking about "the THD meter needle" of the 1970's. I'm talking about the distortion spectrum as we commonly measure it today, down to levels well below 100dB below 1 watt or 1 Vrms. Low distortion always sounds better given the amplifier can deliver the required power at the power levels demanded. That means no current limiting and other factors that commonly confuse this argument. Central to this is the idea that feedback causes problems when in fact it does not. High feedback means lower distortion and lower output impedance (applied in the usual manner). Where feedback got it's bad rap was in earlier designs when the basic amplifier design wasn't very good and feedback was used to band-aide the issues. Get the design right, and feedback improves performance every single time. We measure with single tone (THD, 1 KHz normally) and multitone (IMD, 19 & 20 KHz). Do this at various power levels and you have characterized an amplifier. Do exercise the basic design you can vary the load impedance and reactive component.
By the time you can hear something, it stands out like a very sore thumb when we measure audio today.
So when you say you like low feedback designs, that's cool. It just means you either like the sonic character of a certain amplifier type, or you like a certain amount of distortion. Of course, "sonic character" = distortion.
Whatever you like is a valid choice.
Over my entire career, I have seen a strong correlation between what most people prefer and low distortion. I'm not talking about "the THD meter needle" of the 1970's. I'm talking about the distortion spectrum as we commonly measure it today, down to levels well below 100dB below 1 watt or 1 Vrms. Low distortion always sounds better given the amplifier can deliver the required power at the power levels demanded. That means no current limiting and other factors that commonly confuse this argument. Central to this is the idea that feedback causes problems when in fact it does not. High feedback means lower distortion and lower output impedance (applied in the usual manner). Where feedback got it's bad rap was in earlier designs when the basic amplifier design wasn't very good and feedback was used to band-aide the issues. Get the design right, and feedback improves performance every single time. We measure with single tone (THD, 1 KHz normally) and multitone (IMD, 19 & 20 KHz). Do this at various power levels and you have characterized an amplifier. Do exercise the basic design you can vary the load impedance and reactive component.
By the time you can hear something, it stands out like a very sore thumb when we measure audio today.
So when you say you like low feedback designs, that's cool. It just means you either like the sonic character of a certain amplifier type, or you like a certain amount of distortion. Of course, "sonic character" = distortion.
Very true on the sonic signature. I’ve heard many audio research amps and wasn’t thrilled by them but did hear a few VAC amps that were enjoyable And i know both use feedback may it be local or global. i do like a sprinkle of distortion in the spectrum. I’m also enjoying lower wattage too; around 25-50 watts. It’s looking like depending 300-600 volts will probably yield a great build. ill keep the GM70s in the closet for now
Well, ARC does have it's own sonic signature. Some don't like it along with yourself. CJ sounds different again, as does McIntosh.
I agree, I enjoy an amp I designed around 30~ 35 watts using 6CA7 (it can use 6L6GC as well) tubes. It's really clean. I enjoyed an Eico HF87 rebuilt for a while. But my daily driver is a Marantz 300DC that is modified. Some day maybe a Bryston 4B cubed. I had one to play with for 3 weeks.
Once you depart from very low distortion, people break up into groups as to what effects they like. Speakers play into this as well. So any attempt to argue this is like debating religious beliefs. Just don't go there!
I agree, I enjoy an amp I designed around 30~ 35 watts using 6CA7 (it can use 6L6GC as well) tubes. It's really clean. I enjoyed an Eico HF87 rebuilt for a while. But my daily driver is a Marantz 300DC that is modified. Some day maybe a Bryston 4B cubed. I had one to play with for 3 weeks.
Once you depart from very low distortion, people break up into groups as to what effects they like. Speakers play into this as well. So any attempt to argue this is like debating religious beliefs. Just don't go there!
i'm done with power hungry speakers; been there done that. Since high school everything was high wattage and i've slowly discovered what i like and don't. Over the last few years lower wattage has been great and this is coming from a bass head
I don't want to stay OT for long here ...
My 35 wpc tube amp drove my PSB Stratus Gold speakers okay (4R, ~86 dB/watt), my new Klipsch are more fun, 98 and 99 dB/watt). Those are all different systems. But I am blown away by my friend's Klipsch Jubilee speakers. Just incredible, about 107 dB/watt. Electronic x-over driven by a pair of Bryston 4B cubed. Awesome doesn't even come close to describing the experience. If I could afford pair, they would be in my main system.
One thing the PSB does well. They are pretty flat, and they reach way down in frequency. The Jubilees may get down there, the dual 8" Klipsch towers get close.
The only problem with efficient speakers is getting them to be flat. My friend went through all kinds of horn loaded systems earlier in time. The Jubilee speakers deliver - finally.
My 35 wpc tube amp drove my PSB Stratus Gold speakers okay (4R, ~86 dB/watt), my new Klipsch are more fun, 98 and 99 dB/watt). Those are all different systems. But I am blown away by my friend's Klipsch Jubilee speakers. Just incredible, about 107 dB/watt. Electronic x-over driven by a pair of Bryston 4B cubed. Awesome doesn't even come close to describing the experience. If I could afford pair, they would be in my main system.
One thing the PSB does well. They are pretty flat, and they reach way down in frequency. The Jubilees may get down there, the dual 8" Klipsch towers get close.
The only problem with efficient speakers is getting them to be flat. My friend went through all kinds of horn loaded systems earlier in time. The Jubilee speakers deliver - finally.
107dB/W speakers that “get down there” are huge. If 98dB/W speakers that only get to 100 Hz in half space are bigger than what most people want “speakers” to be.
The good news is that at our age, we really dont want or need it that loud in the home or car. There are still times and places for it, and then I dont give a damn how big and heavy they are. If it takes a hand truck or two people to get them out and set them up, so be it.
The good news is that at our age, we really dont want or need it that loud in the home or car. There are still times and places for it, and then I dont give a damn how big and heavy they are. If it takes a hand truck or two people to get them out and set them up, so be it.
The speakers do have to be huge to reproduce 100Hz due to the wavelength at that frequency, a friend of mine has been working on putting together a huge PA system because he works as a sound tech for some of the live events here in Darwin NT Australia, part of his PA system are a pair of huge sub-woofers that he powers with a couple of Lab Gruppen amps that put-out something like 3000W, you need that much power for reproducing sub-bass frequencies.
Yes, they are huge (Jubilee), they come on four skids.
The room has to be large as well. My speakers are not small, the PSBs are large with 10" woofers, the Klipsch would be RP-8000 if you look them up, they are not small either. But a bass reflex speaker involves throat area and length. Now you're getting into serious sizes.
As for volume levels ... my place sounds like a disco. I have my streamers linked and crank all three systems. I play it loud as heck, especially in the morning getting ready.
The room has to be large as well. My speakers are not small, the PSBs are large with 10" woofers, the Klipsch would be RP-8000 if you look them up, they are not small either. But a bass reflex speaker involves throat area and length. Now you're getting into serious sizes.
As for volume levels ... my place sounds like a disco. I have my streamers linked and crank all three systems. I play it loud as heck, especially in the morning getting ready.
My building partner's pair:
https://www.itishifi.com/hifi/a-little-speaker-upgrade
Roy Delgado is doing some amazing work with the new generation of Klipsch's, porting into the throat of the horn. We've heard the prototypes of the new subwoofers and folks are going to be amazed. I was, and I'm old and cynical.
All good fortune,
Chris
https://www.itishifi.com/hifi/a-little-speaker-upgrade
Roy Delgado is doing some amazing work with the new generation of Klipsch's, porting into the throat of the horn. We've heard the prototypes of the new subwoofers and folks are going to be amazed. I was, and I'm old and cynical.
All good fortune,
Chris
Hi Chris,
I have to agree, they are amazing! But brutally honest. They will show up any defect in electronics or source material. Any low level hum or noise isn't low level on the Jubilee speakers.
Yes, the horn loaded woofers are ported as well. Very effective. So ... they have new ones coming out? Better than the Jubilees? !
I have to agree, they are amazing! But brutally honest. They will show up any defect in electronics or source material. Any low level hum or noise isn't low level on the Jubilee speakers.
Yes, the horn loaded woofers are ported as well. Very effective. So ... they have new ones coming out? Better than the Jubilees? !
New subs are in prototyping and will probably/mostly have (as conventionally) integral amplifiers. I was most impressed with the smallest ones, 8" woofer, very small box, woofer back chamber ported into the (very small) horn's throat. Looks like it couldn't possibly work, very surprising.
There are woofers in the pro-sound line the size of refrigerators that might compete with the Jub's, and Iain has one. Since he got his Jub's that woofer just sits out on the back porch.
All good fortune,
Chris
There are woofers in the pro-sound line the size of refrigerators that might compete with the Jub's, and Iain has one. Since he got his Jub's that woofer just sits out on the back porch.
All good fortune,
Chris
lol!
Most speakers are headed outside once a pair of Jubilees show up!
I used to do warranty on Klipsch back in the late 80's and 90's. My mom has one of the first models with an 8" and the Tractrix horn, loves them. I wish I could afford a pair of RF-7 III, Jubilees are way out of range. I have to win a lottery!
Not a fan of subs with integral amps. Especially class D. They get shaken around a lot, and for lack of service information they are not repairable. Call it a strong dislike for that trend.
Most speakers are headed outside once a pair of Jubilees show up!
I used to do warranty on Klipsch back in the late 80's and 90's. My mom has one of the first models with an 8" and the Tractrix horn, loves them. I wish I could afford a pair of RF-7 III, Jubilees are way out of range. I have to win a lottery!
Not a fan of subs with integral amps. Especially class D. They get shaken around a lot, and for lack of service information they are not repairable. Call it a strong dislike for that trend.
Gotta agree. And Klipsch is not great about parts and service support. Hate to say it, but it's true.
Chris
Chris
Hey Chris, it's everyone. Not just Klipsch. They are great with drivers and everything else.
Most people consider one and a half cubic feet to be TOO BIG. That’s why speakers today are so inefficient. That’s a very small PA speaker - about the size of my vocal wedges which are good to 100 Hz. I’ve got multiple 32 cubic foot subs on tap when I do turn the shop (or outside) into a disco but those sound levels just have no place in the home. The speakers barely fit in the door, take up The Whole Room, and where the hell do I put the light show? 20-40 watts per channel and a pair of “they’re too big” 1.5 cf 84 dB/W 10” 3 ways provides all the output needed (including the bass) for daily use. For just typical club levels in the shop the 2x15’s and the 200W tube monoblocks do very well. I dont even do that every day.
Really good headphones can cover very low frequencies.
Low frequency response is dependent on many factors.
I do remember going to a hi fi warehouse with a friend. He was interested in the Bose Model 9.
We listened to a few music cuts. I asked to hear a pipe organ play some low bass. Model 9 . . . OK.
Then I asked to play the same organ track on the AR3a. You could Feel the notes.
My friend left with a pair of AR3a speakers.
Low frequency response is dependent on many factors.
I do remember going to a hi fi warehouse with a friend. He was interested in the Bose Model 9.
We listened to a few music cuts. I asked to hear a pipe organ play some low bass. Model 9 . . . OK.
Then I asked to play the same organ track on the AR3a. You could Feel the notes.
My friend left with a pair of AR3a speakers.