I read the article from Mr Kobayashi years ago through Plitron website
http://www.plitron.com/PDF/GLASSkoby.pdf, made some simulations in my computer and bought Hammond 1627 and 300BX but nothing has been done until now.
Anybody can give me comments on how it sound and is it worth to build? Or should I look for alternative schematics?
FYI: Lately I hear mostly from FLAC-DAP, also hires recordings for Jazz and Classics. Either I will pair it with LS 3/5a or Quad floor standing speakers.
many thanks,
http://www.plitron.com/PDF/GLASSkoby.pdf, made some simulations in my computer and bought Hammond 1627 and 300BX but nothing has been done until now.
Anybody can give me comments on how it sound and is it worth to build? Or should I look for alternative schematics?
FYI: Lately I hear mostly from FLAC-DAP, also hires recordings for Jazz and Classics. Either I will pair it with LS 3/5a or Quad floor standing speakers.
many thanks,
Some remarks:
- It is very complicated for a 300B, with an over-complex driver and solid state power circuits, that will need a pair of circuit boards to do right.
- it was designed more than 15 years ago, so you will find that some of the parts are now obsolete & unavailable. The power FET in the HV supply is fairly likely in this category, and even the SV300B.
300B SE can sound excellent if built fairly simply, with high quality power supply parts. A choke-input filter (10-15H, 130mA per channel), and AMPOHM or ClarityCap polypropylene caps in a LCLC supply, fed from TV damper diode rectifiers and a 200VA transformer (per channel).
Purpose-built current-driven filament supply is essential.
For the driver, simple can be excellent too - try the SV83 or EL84 pentode driver (single stage), as used in the "La Maison de l'Audiophile" 300B.
With this approach, you can built it point-to point, and make it your own.
- It is very complicated for a 300B, with an over-complex driver and solid state power circuits, that will need a pair of circuit boards to do right.
- it was designed more than 15 years ago, so you will find that some of the parts are now obsolete & unavailable. The power FET in the HV supply is fairly likely in this category, and even the SV300B.
300B SE can sound excellent if built fairly simply, with high quality power supply parts. A choke-input filter (10-15H, 130mA per channel), and AMPOHM or ClarityCap polypropylene caps in a LCLC supply, fed from TV damper diode rectifiers and a 200VA transformer (per channel).
Purpose-built current-driven filament supply is essential.
For the driver, simple can be excellent too - try the SV83 or EL84 pentode driver (single stage), as used in the "La Maison de l'Audiophile" 300B.
With this approach, you can built it point-to point, and make it your own.
long time lurker here - Some thoughts:
i was like you, except worse as i had collected enough iron for 3 or 4 monoblocks. i was building the J.E labs EL34 SE mojo in monos at first (i've already rebuilt vintage guitar and hifi amps, but nothing from 'scratch') and, for 2 years, kept stalling the build. then i basically said, wtf, lets build something -
i've got the J.E./Angela/Walton 'WE-91 clone' - 2 monoblocks now running, all set on 2 cheap hammond steel 8"X16"X2" chassis, the iron is Edcor for Power Trans and the 10H x200ma chokes, an additional (or dedicated) Hammond 5v PT, OTs are One Electron's UBT3s, and i'm flipping between C (or RC) coupled and IT - Hammond 126c's - which i'm preferring currently and they 'drop in' with no fuss, but will try other caps later - current is orange drop. Other than the 'pain' of layout planning and then the punching and drilling/deburring (hint: work with gloves),etc. i only had one problem, a hum due to my grounding CT of PTX at first which i quickly corrected (even though one doesn't have to use hum pot with a CT PTX... but that's another thing to debate when assembling yours!), otherwise, it was a fairly fast build once i got my **** moving and had most parts to stop the excuse that i didn't have "everything..." oh, current glass is NOS random 5U4Gs, NOS RCA 6SN7GTs, EH gold pin 300Bs.
Being cautious, i had the things only in garage playing FM or PC/iPhone to homemade speakers or little sat NHTs over the winter, and finally, last spring, brought them in to try vs. my dynaco Mk3s and ST70 (plus 2 PAS's, 1 modded, 1 original except lytics/selenium replaced) - again, PC and normal modern 2 volt sources sound good but plying vinyl through my PASs sounded horrible, out of phase almost, and i like records, so i let them set around unused - long story short - i cut in another input & switch, a SPDT for each, bypassing the 100k pot and loaded those 2nd inputs with 470k to ground - finally, i can use them with the PASs - ok, how do they ''sound"? they sound just as good, although different from the ST70 (it's triode wired currently) and better than the Mk3's in UL although they beat both in low end. how they compare to SS of any quality i cannot say since i have none to actively compare.
Anyway, i'll do more mods, the 2 stage 6SN7 is too much gain so, first is to go to a 6j5 or 76, which I have, or who knows, maybe something completely different if that's not enough 'swing', anything as long as i can keep the chassis work to a minimum, which to me is the overlooked and under studied part of this pursuit if you technically competent with soldering and reading schematics (and always - safety first, otherwise it will be a short hobby!)
Best regards - Wal
i was like you, except worse as i had collected enough iron for 3 or 4 monoblocks. i was building the J.E labs EL34 SE mojo in monos at first (i've already rebuilt vintage guitar and hifi amps, but nothing from 'scratch') and, for 2 years, kept stalling the build. then i basically said, wtf, lets build something -
i've got the J.E./Angela/Walton 'WE-91 clone' - 2 monoblocks now running, all set on 2 cheap hammond steel 8"X16"X2" chassis, the iron is Edcor for Power Trans and the 10H x200ma chokes, an additional (or dedicated) Hammond 5v PT, OTs are One Electron's UBT3s, and i'm flipping between C (or RC) coupled and IT - Hammond 126c's - which i'm preferring currently and they 'drop in' with no fuss, but will try other caps later - current is orange drop. Other than the 'pain' of layout planning and then the punching and drilling/deburring (hint: work with gloves),etc. i only had one problem, a hum due to my grounding CT of PTX at first which i quickly corrected (even though one doesn't have to use hum pot with a CT PTX... but that's another thing to debate when assembling yours!), otherwise, it was a fairly fast build once i got my **** moving and had most parts to stop the excuse that i didn't have "everything..." oh, current glass is NOS random 5U4Gs, NOS RCA 6SN7GTs, EH gold pin 300Bs.
Being cautious, i had the things only in garage playing FM or PC/iPhone to homemade speakers or little sat NHTs over the winter, and finally, last spring, brought them in to try vs. my dynaco Mk3s and ST70 (plus 2 PAS's, 1 modded, 1 original except lytics/selenium replaced) - again, PC and normal modern 2 volt sources sound good but plying vinyl through my PASs sounded horrible, out of phase almost, and i like records, so i let them set around unused - long story short - i cut in another input & switch, a SPDT for each, bypassing the 100k pot and loaded those 2nd inputs with 470k to ground - finally, i can use them with the PASs - ok, how do they ''sound"? they sound just as good, although different from the ST70 (it's triode wired currently) and better than the Mk3's in UL although they beat both in low end. how they compare to SS of any quality i cannot say since i have none to actively compare.
Anyway, i'll do more mods, the 2 stage 6SN7 is too much gain so, first is to go to a 6j5 or 76, which I have, or who knows, maybe something completely different if that's not enough 'swing', anything as long as i can keep the chassis work to a minimum, which to me is the overlooked and under studied part of this pursuit if you technically competent with soldering and reading schematics (and always - safety first, otherwise it will be a short hobby!)
Best regards - Wal
It's not that much more complex than some of my older designs, but the tube choices are uninspired to say the least, and the operating current in both stages is too low.
Chose something like the 5687 for the white cathode follower and run it at at least 10mA, a 12AX7A running at something approaching 1mA would drive the WCF decently.
Still much simpler designs with a single triode connected D3A or 7788 into an IT or choke would do a much better job.
Chose something like the 5687 for the white cathode follower and run it at at least 10mA, a 12AX7A running at something approaching 1mA would drive the WCF decently.
Still much simpler designs with a single triode connected D3A or 7788 into an IT or choke would do a much better job.
Thanks, for the inputs.
For power supply I was tending to modern design using solid state because I am not sure whether tube rectification with choke can have a fast recovery energy supply.
I will look at the "La Maison de l'Audiophile" 300B and 5686/12AX7A follower.
My approach is more on the ability for hearing music. I don't like to experiment too much and better have a good and proven schematics at once. Money is not a big constrain for me. Time and effort but yes.
For power supply I was tending to modern design using solid state because I am not sure whether tube rectification with choke can have a fast recovery energy supply.
I will look at the "La Maison de l'Audiophile" 300B and 5686/12AX7A follower.
My approach is more on the ability for hearing music. I don't like to experiment too much and better have a good and proven schematics at once. Money is not a big constrain for me. Time and effort but yes.
Solid-State Regulation for the main supply is more difficult than it looks! Kobayashi's design uses a passive zener follower, which will not be fast at all.
I was going to refer to the components used in that design, but I see that Plitron have now taken it down!
In fact any design using a power FET driven by tens of Kilohms of pull-up resistor will fail to keep up with the current slewing of a 300B, simply due to the huge (nanoFarad level) input capacitance of the FET.
I suspect that this is why they usually sound much worse than LCLC supplies.
It's different with the driver power supply though - the current swings are small, and the low noise and dc stability of a power-FET supply are helpful.
With DHT Filaments, solid state regulators are certainly necessary, but beware of using a voltage regulator. If you do, the (differential) music signal across the filament will get mixed into the regulator's feedback loop. You then have a heavy 1.2A regulator chasing after the mA-level music signal - resulting in the shrill, hard sound that most folks report when trying it. Purpose-designed current-driven filament heating solutions, like Guido's modules, or my "Coleman Regulators" give much better sound.
I was going to refer to the components used in that design, but I see that Plitron have now taken it down!
In fact any design using a power FET driven by tens of Kilohms of pull-up resistor will fail to keep up with the current slewing of a 300B, simply due to the huge (nanoFarad level) input capacitance of the FET.
I suspect that this is why they usually sound much worse than LCLC supplies.
It's different with the driver power supply though - the current swings are small, and the low noise and dc stability of a power-FET supply are helpful.
With DHT Filaments, solid state regulators are certainly necessary, but beware of using a voltage regulator. If you do, the (differential) music signal across the filament will get mixed into the regulator's feedback loop. You then have a heavy 1.2A regulator chasing after the mA-level music signal - resulting in the shrill, hard sound that most folks report when trying it. Purpose-designed current-driven filament heating solutions, like Guido's modules, or my "Coleman Regulators" give much better sound.
hello - i'll clarify my previous (and badly misspelled/proofed) post by saying that after way too much deliberation, i decided to go with something fully detailed yet simple and proven with what i had already acquired and that was somewhat compatible with existing speakers (~94db/watt), etc., so, you may want something more - anyway, the straight up JE/Walton 300B is not a bad place to start if, assuming, you want to experience that SET 'magic' right off, but given your speaker choice (Quad ESL) - i find the triode wired PP el34 a good first place to start, even though you have a SE OT, but don't let hoarding of parts stop you, is my main point ;^) The PDF you posted is a good if not great solution to the planning/layout/drilling etc issue i was alluding to, which the Derek Walton plans helped me tremendously with - have pix but not sure how to upload...
here's an attempt:
here's an attempt:
Attachments
I have been looking around for schematics done in Internet and found that:
1 300B SET driven using EL84 is very seldom. I stuck on a schematic done by Thorsten Lösch. It's based on We91 and should sound good. There are excessive R and C in the schematic and I just can't stand the valve regulated power supply which is very complicated. One should use original version I think.
2 White Cathode Follower is used mainly for OTL system. I can't find any properly designed schematic for 300B SET except using Aikido as base circuit.
3 Interesting is two designs. One by Andrea Ciufioli for current control using LM317 I think it's worth to try and another one by an engineer in Florida he use MOSFET in the stage driver to separate input and output.
1 300B SET driven using EL84 is very seldom. I stuck on a schematic done by Thorsten Lösch. It's based on We91 and should sound good. There are excessive R and C in the schematic and I just can't stand the valve regulated power supply which is very complicated. One should use original version I think.
2 White Cathode Follower is used mainly for OTL system. I can't find any properly designed schematic for 300B SET except using Aikido as base circuit.
3 Interesting is two designs. One by Andrea Ciufioli for current control using LM317 I think it's worth to try and another one by an engineer in Florida he use MOSFET in the stage driver to separate input and output.
This one
http://www.ankaudiokits.com/PDF/Kit1 pdf Output - Hammond.pdf
My approach is a bit limited since i own already one Hammond 300BX and two 1627SE bought couple years ago and I intend to use these in the project.
http://www.ankaudiokits.com/PDF/Kit1 pdf Output - Hammond.pdf
My approach is a bit limited since i own already one Hammond 300BX and two 1627SE bought couple years ago and I intend to use these in the project.
Last edited:
Be careful, with : 5 V CT @ 1,2 A you can't use DC filament supply, only AC. (not enough A)
with 5 V CT @ 3 A you can. But you have to use one winding for each 300B, otherwise it is connecting the cathodes together. (not good for stereo)
with 5 V CT @ 3 A you can. But you have to use one winding for each 300B, otherwise it is connecting the cathodes together. (not good for stereo)
Yes, this is certainly true.
But using an all-in-one transformer for B+ and dc filaments will result in disappointing results. This is because the Ampere-level capacitor recharge pulses in the filament supply will cross-couple to the B+ supply (and the other way around).
In every case, a separate transformer for filaments is better.
The 78S05 in the Audio note circuit needs a bigger heatsink than the one in the AN kits, or it is liable to shut down by itself (overheating). This is not to mention the bad sound you get with 3-terminal regulators.
If the filament supply is compromised in any of these ways (integral transformer, or ac-heating, plain rectified dc, or voltage regulator chips) it would be better to use a triode-connected JJ KT66 or KT88 than proceed with DHTs, even if the hum level is acceptable ... which is unlikely.
The 300B makes a superb SE amplifier, but only if all of the power supply stages are up to scratch. B+ and Filament. Compromises or cost-cutting will only produce results that are inferior to the compromise of triode-connecting a beam-tube. (The problems with the beam-tube can easily be seen by drawing an elliptical load-line over its triode curves).
No need to take my word for it, though. Leave room in your chassis for separate filament transformers, and try for yourself, and listen.
Rod & Costis,
Guys, I studied EE and all your statements makes sense to me.
What bothers me in the AN circuit is the filament heating parts. AC heating makes more sense or according to Rod better a separate transformer.
What makes sense in the circuit is they put the potentiometer between the 1st and 2nd stage driver. That means take 100% audio signals first (which is still weak and proner to distortion) and adjust it later. I like the idea.
PS: I won't buy the AN kit but instead make modifications and do P2P wiring. I heard the kit sold outside Japan for many people is not satisfactory.
Guys, I studied EE and all your statements makes sense to me.
What bothers me in the AN circuit is the filament heating parts. AC heating makes more sense or according to Rod better a separate transformer.
What makes sense in the circuit is they put the potentiometer between the 1st and 2nd stage driver. That means take 100% audio signals first (which is still weak and proner to distortion) and adjust it later. I like the idea.
PS: I won't buy the AN kit but instead make modifications and do P2P wiring. I heard the kit sold outside Japan for many people is not satisfactory.
Actually this is the worst idea in this schematic. As a power amplifier, it accepts 1..2 VRms signals from sources that have output Z of 600 Ohms or less. Not weak at all.Better have the volume at the input, or not at all, if you have a preamp.
Is it a coincidence it does not appear on any other of their 300b schematics? Just replace it with one resistor.
In any case, if you go AC heating, here is a nice pdf explaining how to do it properly, it caught my eye in the AudioNote pdf is not done in a balanced way.
http://www.jacmusic.com/techcorner/...07-How-to-bias-DHT-tubes-without-mistakes.pdf
http://www.jacmusic.com/techcorner/...07-How-to-bias-DHT-tubes-without-mistakes.pdf
Curiously, when DHT amplifiers are constructed so that the filament heating does not interfere with the music (meaning: No ac-heating, and No dc-heating with mV of noise - like Jac's application note suggests you use!) - then we find that the "centre-tap" resistors make worse sound than single-sided termination. The loss is of much of the 3D sound-space, that makes a DHT so attractive in the first place.
Sure, the noise cancelling method works, of a sort. Current from each opposing phase cancels mostly, to remove the gross part of the humm, but it does not prevent the unnatural-sounding intermodulation.
It does not cancel perfectly with ac-heating, because the ac-voltage generates harmonics of its own frequency in the output (100/120Hz from 50/60Hz), as well as intermodulation cross-products with the music. For this reason ac-heated DHT stages can barely claim to be called hi-fi.
The centre-tapped resistor network is not needed on correctly designed dc current-heating schemes. There is little excuse for using high common-mode capacitance transformers, since any old cheap 50VA EI split-bobbin type has only 50pF or so of leakage capacitance, and the frame can be grounded.
There is even less reason to accept mV levels of noise on a dc supply. Even the LM317, which makes a mediocre heater due to leakage paths between output and feedback network, has lower noise than that.
I find it strange that Jac is promoting the EML tubes (which cost Euro 400 to 800+ per pair) using such poor-quality heating schemes, whose flaws can be so easily measured. Correctly-implemented current-driven heating allows the DHT to give its best, with noise so low that there's no need for any noise-cancelling fudges.
Reading this thread suddenly made me wonder, how big of an impact does the choice heater supply make on the perceived bass quality with DHT's? A friend of mine who's been designing tube equipment for decades said he's never managed to get good bass from a pair of 300B's. Regardless of the output transformers.
- Status
- Not open for further replies.