Evenharmonics my old room was completely treated, my new room isn't yet. I know how critical room treatment is.
I have to agree with the others a good design, good transformers and proper matching with efficient speakers can provide very satisfactory results.
I do not have any fo. runs for my new 45 based amp but I took a look at the runs I did a couple years ago on my 2a3 Moondogs and Lowther Medallions.
My -3db in room response of the Lowthers only was about 55 hz. By adding a fast sub (I know I should use two) I was able to get the -3db response down to about 23 hz.
I'm happy!
I do not have any fo. runs for my new 45 based amp but I took a look at the runs I did a couple years ago on my 2a3 Moondogs and Lowther Medallions.
My -3db in room response of the Lowthers only was about 55 hz. By adding a fast sub (I know I should use two) I was able to get the -3db response down to about 23 hz.
I'm happy!
I'll second the Hammond transformers. I have a KT88 SET that is similar to the ones scitizen17 is selling. I've also used the Hammond 1628SEA (5k vs 2.5k) and have no problems with bass (the trannies weigh 11lbs each!)
JMTC
Glenn
Response to Jay regarding loss of bass in newer music
Jay,
You are not alone in missing bass in modern music recorded on CD's. If the music was recorded, just as it is played, no one could stand to listen to it. A fact of life is that all music recorded on a CD is distorted and I don't mean in just a moderate measure. I am a former recording engineer and once I saw all of the tricks used by the newer recording engineers, I decided enough for me and quit the field. Once the newer boards were brought in, too many fingers got into the mix. Give me a good record any-day and I will show you some of the greatest music ever recorded and that goes way back to the early days of vinyl. I enjoy listening to my record collection, almost every day and use only tube gear. Tubes 4 me
Jay,
You are not alone in missing bass in modern music recorded on CD's. If the music was recorded, just as it is played, no one could stand to listen to it. A fact of life is that all music recorded on a CD is distorted and I don't mean in just a moderate measure. I am a former recording engineer and once I saw all of the tricks used by the newer recording engineers, I decided enough for me and quit the field. Once the newer boards were brought in, too many fingers got into the mix. Give me a good record any-day and I will show you some of the greatest music ever recorded and that goes way back to the early days of vinyl. I enjoy listening to my record collection, almost every day and use only tube gear. Tubes 4 me
You could cross the source down at some frequency to SS as mentioned before,
or try something a little more bizarre than crossing: SS=A+B, SET=A-B,B-A
Sum back to A and B at the OPT secondary, or send to three speakers as-is.
Of course, this way holds no advantage for source recorded entirely in mono...
or try something a little more bizarre than crossing: SS=A+B, SET=A-B,B-A
Sum back to A and B at the OPT secondary, or send to three speakers as-is.
Of course, this way holds no advantage for source recorded entirely in mono...
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I use Fostex206E in hornes, something like Dallas, I heard 35 Hz and last string of chelo and bass is enough big. Hornes have amazing sound.
I don´t know what listening levels you need.
But with a 2 ohm speaker and bass you need a lot of current.
2ohm, current and SE is an challenging mix 😀.
I´d say give the amp a 100+dB speaker setup with an normal load and you´ll have enough to blow the roof.
But with a 2 ohm speaker and bass you need a lot of current.
2ohm, current and SE is an challenging mix 😀.
I´d say give the amp a 100+dB speaker setup with an normal load and you´ll have enough to blow the roof.
The problem oftentimes is the QUALITY of the bass more than the quantity. What is often verbalized as "lack of bass" can be corrected by adding definition, resolution and punch to the lower register. The same things that help bass quality also add resolution to the sound overall.
Some of these things have been mentioned in this thread already, but just to sort of sum up my own experiences, these are things that make an SET amp rock (or whatever you do with house or EDM):
1) Parafeed. No need to talk about the OT once you go parafeed. With no DC in the primary, the OT will perform two or three 'classes' above it's price and weight. Even a lowly Hammond will do surprisingly good in parafeed.
Use MOSFET gyrators on all stages, even the output. Take the output from the MOSFET source.
Use a high quality parafeed cap; the quality of this cap is paramount. Russian caps are very very cheap and as per quality, can't be beat in my opinion. KBG MN is the way to go. Use as small as you can get away with.
2) PS regulation. Even a simple 2 MOSFET regulator with some zeners, one MOSFET passes, the other is an error amp, will significantly increase bass quality and often quantity also, if it is lacking. If you have the space and a couple of bucks, there really is absolutely no reason to NOT regulate B+.
3) No RC bias. Go with fixed bias, either grid or diode (LEDs for example). I find fixed grid bias to be best for bass quantity and quality. Best resolution. For simplicity, LED bias is good also, if applicable.
4) Depending on the output stage, what tube you use, it can be beneficial to have CCS help out with the parafeed OT. Have a CCS between the plate loads source and ground. Put about 10mA thru it. Sometimes this has a surprising add of punch to the sound. The bass starts really hitting the air. But again, this is usefull with some tube + OT combinations, on others not so much. Worth a try still, after doing all of the above.
All of these keep (and improve) the 3D imaging and resolution and transparency of the amp, but can have a big impact on bass quantity and quality. This is how I do SET.
Some of these things have been mentioned in this thread already, but just to sort of sum up my own experiences, these are things that make an SET amp rock (or whatever you do with house or EDM):
1) Parafeed. No need to talk about the OT once you go parafeed. With no DC in the primary, the OT will perform two or three 'classes' above it's price and weight. Even a lowly Hammond will do surprisingly good in parafeed.
Use MOSFET gyrators on all stages, even the output. Take the output from the MOSFET source.
Use a high quality parafeed cap; the quality of this cap is paramount. Russian caps are very very cheap and as per quality, can't be beat in my opinion. KBG MN is the way to go. Use as small as you can get away with.
2) PS regulation. Even a simple 2 MOSFET regulator with some zeners, one MOSFET passes, the other is an error amp, will significantly increase bass quality and often quantity also, if it is lacking. If you have the space and a couple of bucks, there really is absolutely no reason to NOT regulate B+.
3) No RC bias. Go with fixed bias, either grid or diode (LEDs for example). I find fixed grid bias to be best for bass quantity and quality. Best resolution. For simplicity, LED bias is good also, if applicable.
4) Depending on the output stage, what tube you use, it can be beneficial to have CCS help out with the parafeed OT. Have a CCS between the plate loads source and ground. Put about 10mA thru it. Sometimes this has a surprising add of punch to the sound. The bass starts really hitting the air. But again, this is usefull with some tube + OT combinations, on others not so much. Worth a try still, after doing all of the above.
All of these keep (and improve) the 3D imaging and resolution and transparency of the amp, but can have a big impact on bass quantity and quality. This is how I do SET.
I didn't thought that this was an issue. But after looking at the zen triode I see your issues. And what people say, there is some of it that works some of the time. Which does make me wanna buld consumer stuff and sell it. I left alone the consumer world and only worked for special builds in pro audio world. Maybe since that demand is dieing down, I need to go this direction.
Are you a DIYer? I am not, but my experience with SETs as a listener is fairly broad.
If you're not a DIYer and have to rely on the commercial SET market or a custom SET builder, you will have to pay serious money for the bass you want.. for the amp, for the speakers, and the treatments to your room to take care of resonant frequencies below 50-55 Hz, which is often a problem in homes with standard sheet-rock walls.
The reasons have already been given by others.
I would not dismiss all tube amps as having no bass.
Suggest you try tube rolling your input, output and rectifier tubes.
On my SE EL34 tube amp, I got the "missing" bass after tube rolling the tube rectifier.
My mids, treble and bass and soundstage became "glorious" after I got a pair of NOS Metal base EL34s to replace the NOS Mullard XF2s.
Suggest you try tube rolling your input, output and rectifier tubes.
On my SE EL34 tube amp, I got the "missing" bass after tube rolling the tube rectifier.
My mids, treble and bass and soundstage became "glorious" after I got a pair of NOS Metal base EL34s to replace the NOS Mullard XF2s.
OTL..
No Op Tx..I have no problems with bass on the OTL..
I can also say I have heard good bass from the vellman K4000 series it has Toroid Op Tx's. Not sure how it would sound with a better driver stage..Put a couple of old tannoy 611 on it and the bass will shake your guts..how much bass is to much bass..Feedback can have an impact as well.
So you have to ask yourself ..is it a power issue..or a speaker issue..or Output transformer or OP stage type..
Remember the SVT Bass amp<<tube...for bass guitar..
But there is a difference with bass<<<there is THUMP..THUMP...or there is I can hear the strings on the bass guitar...You can get both quite easily.
Here was a test done with OTL playing Deadmau5 there is just Alpair 7 speakers (Front ported) no sub or anything else..remember it was done with a mobile phone.
Sorry for double posting the link its a bit old now but its the easiest way to show it.
http://www.youtube.com/watch?v=TU2YCTps69U&NR=1&feature=endscreen
http://www.youtube.com/watch?v=0B_JTYYLdN4
Regards
M. Gregg
No Op Tx..I have no problems with bass on the OTL..
I can also say I have heard good bass from the vellman K4000 series it has Toroid Op Tx's. Not sure how it would sound with a better driver stage..Put a couple of old tannoy 611 on it and the bass will shake your guts..how much bass is to much bass..Feedback can have an impact as well.
So you have to ask yourself ..is it a power issue..or a speaker issue..or Output transformer or OP stage type..
Remember the SVT Bass amp<<tube...for bass guitar..
But there is a difference with bass<<<there is THUMP..THUMP...or there is I can hear the strings on the bass guitar...You can get both quite easily.
Here was a test done with OTL playing Deadmau5 there is just Alpair 7 speakers (Front ported) no sub or anything else..remember it was done with a mobile phone.
Sorry for double posting the link its a bit old now but its the easiest way to show it.
http://www.youtube.com/watch?v=TU2YCTps69U&NR=1&feature=endscreen
http://www.youtube.com/watch?v=0B_JTYYLdN4
Regards
M. Gregg
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It seems the lack of inductance caused by the standing DC asnd air gap are the main problem. Difficult to solve since higher inductance SE transformers are very expensive.
I suggest two possible solutions;
- Use very low output impedance valves such as the 6as7 (not good in SE)
-try DC compensated PP output transformers. These can maintain much higher inductances with relatively smaller output transformers. They should also offer better high frequency response.
I run 6AS7's in class A PP with plate to grid feedback, the bass is very tight right down to about 20hz, so it is possible to get good base from tubes.
Shoog
I suggest two possible solutions;
- Use very low output impedance valves such as the 6as7 (not good in SE)
-try DC compensated PP output transformers. These can maintain much higher inductances with relatively smaller output transformers. They should also offer better high frequency response.
I run 6AS7's in class A PP with plate to grid feedback, the bass is very tight right down to about 20hz, so it is possible to get good base from tubes.
Shoog
In the particular case of the Decware Zen Select, the bass response level is probably set by the coupling cap (0.01 microF) and the grid leak resistor of the power tubes (330K). Predicted -3 dB point: 48 Hz unless I'm mistaken. This may have to do with OPT limitations and relevant choices made by the designer, as has been mentioned upthread.
Valve amplifiers tend to have poor bass due to the output transformer.
To get really good bass requires a large transformer and so high cost.
Many companies skimp on the output transformer due to its cost.
To get really good bass requires a large transformer and so high cost.
Many companies skimp on the output transformer due to its cost.
well with this circuit.
I would change the .01 caps to 1uf 630V solen poly cap.
change input volume control to 250K.
add a 220uf 50V across 100 ohm resistor in output cathodes circuit (negative lead to ground).
I would change the .01 caps to 1uf 630V solen poly cap.
change input volume control to 250K.
add a 220uf 50V across 100 ohm resistor in output cathodes circuit (negative lead to ground).
I have come to realize that the main limitation of this amp is due to the transformer. It's just not designed to dig down low for modern music. I am using it with a subwoofer and that helps quite a bit but I think I will have to build my own amp in the future that is designed to go low.
A quick side note, I recently modified this amp to have regular and led bias. The led bias has improved things across the board and is going to be a stable of any amp I have in the future.
A quick side note, I recently modified this amp to have regular and led bias. The led bias has improved things across the board and is going to be a stable of any amp I have in the future.
+1
I have converted my 6C4C SE amp to parafeed with LED bias - 3,5W and 89dB speakers - more than enough.
How do you load your power tube? A big resistor, a choke, or another tube? Yes, not having DC on your output transformer lessens the size of the core but you also have to add other things to the circuit, not to mention a big output capacitor. No free lunch.
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