Wavelength Bugle Type 45 schematic

[dowto1000]

I just looked up, after seeing some of you refer to the Bugle in this Forum, the Bugle Type 45's schematic..

It is a PERFECT EXAMPLE of how to very easily get more audio performance, as a result of a different B+ filter to the Finals.

Look at the schematic, it has a Hammond 159L choke specified. Look that up, it has 429 Ohms of DC resistance

I have found, ever since 1982, that tube amps' chokes need to be 20 Ohms or less, to play as high in performance as the tube is able.


So, I would suggest using two 10 Ohm chokes, in place of any single 429 Ohm choke, going to the Finals. As in L1/C1/L2/C2.

Anyone using THAT 157 L, I promise you, has not remotely heard what is possible through your amp. See all my other posts for background.



If you have one of these Bugles, can DIY, and would like me to possibly re-design it for you, for free as I have time, please let me know.

It needs different small Hammond chokes ( under two pounds), and it will be 21 TIMES lower in series resistances, to TRANSFER Power Supply ENERGY appropriately..... on music's demand..

Have fun, I do.

Dowto1000

 

[TubeHiFiNut]

Was the schematic supposed to be attached or did I miss the link?

 

[dowto1000]

I have been working on, thinking about, the Yamomoto A-08 the last few days.

I have developed two ways to direct couple it and to "fix" that nasty 10 HY / 100 Ohm choke in the supply.

But the approach I developed using a new / stock Hammond Power Transformer, does not yet totally please me.

A second schematic I have developed, is pretty nice, but it involves a custom wound power transformer and custom chokes, which I do not want to have DIY builders do, if I can possibly avoid it.

Sometimes, 'ya gotta let the circuit " roll around in yer head " for a few additional days, or maybe a week, to see IF an alternative, and better course of action, comes up. High performance, elegant, and not too costly ! KISS rules.


Dowto1000

 

[Opa1]

I'm guessing he's referring to my Bugle 2A3. I used the Gordon Rankin Bugle 45 schematic but set up for 2A3 use. http://www.wavelengthaudio.com/bugle.pdf . I did not use the schematic power supply. I used two small chokes (similar to what dowto1000 is referring to) in a CLCLC setup. First cap is very small to adjust voltage. The chokes are not as small as what he's using.

 

[dowto1000]

I'm guessing he's referring to my Bugle 2A3. I used the Gordon Rankin Bugle 45 schematic but set up for 2A3 use. http://www.wavelengthaudio.com/bugle.pdf . I did not use the schematic power supply. I used two small chokes (similar to what dowto1000 is referring to) in a CLCLC setup. First cap is very small to adjust voltage. The chokes are not as small as what he's using.

That is great !!!

That Hammond 157L choke is a real poor design choice for filtering the Finals.

In 1982, Bob Fulton said to me the " 2A3 is a 'direct-access-to-the-music device' and as such, it needs a truly great supply, low in DC resistances."

Only if you have the time and inclination, please send me your schematic, with voltages ( starting with the at-idle AC voltages on the HV secondary of the power transformer ). I would have FUN looking it over. You know, send me more than what I initially sent to you . :-)

I LOVE two stage amps, but I do not want to ever see them them cap coupled . A capacitor is the worst way to couple two stages, and conversely, a direct couple is the most effective way.

Discussion :

A BIG problem with any and all two-stage cap-coupled amps' topology I see, is that it is VERY hard to get good decoupling of the driver stage B+, from the Final stage B+.

Realize this, each stage has RADICALLY different supply requirements, and if you optimize one stage, the other suffers DUE TO A LACK OF DECOUPLING. They unfortunately operate at the same, (or close to) each other's B+ voltages.

A person could build two separate supplies, for each stage, filtered according to the stage's needs, ....but why bother ? After all that work and expense, you still are coupling the two stages in the worst way possible, with a crummy, easy-to-eliminate coupling cap !!

Realize this sir,: as soon as you DIRECT COUPLE, you gain a MUCH more favorable topology for the power supply.

Having the direct coupled amp's second stage's B+ elevated 150 to 190 VDC above the first stage's B+, allows one to automatically be able to PROPERLY DECOUPLE ( R/C ) the front end stage B+and the high-current, higher voltage Finals stage's B+. Lovely !!

BOTH stages' B+ can be thus be designed according to their own needs, with an optimized power supply for each stage's needs. ( R2). This decoupling and differing B+ voltage topology, inherent in a Direct Coupled two-stage amp's topology, is hugely advantageous. .

Replacing ANY cap coupling, is the second LOVELY sounding advantage.

A short length of high quality wiring, sure has a better TRANSFER EFFICIENCY, than any series coupling capacitor. An easy choice, if you simply THINK about it. Its MUCH easier, NOT having to drive the energy-robbing non-linear coupling capacitor, and to power the Final's grid with a direct couple.

Below, is a fun article from 1994, Sound Practices Magazine by Marzio and Jelasi. I certainly can NOT recommend building this amp verbatim, according to the schematic they present. Several changes beg to be applied. Ask me, if you need help. .

//www.ispra.net/audio/DCSingleEndedAmplifier/index.php

Dowto1000

 

[Opa1]

I enjoy your enthusiasm. I also understand your design topology. I built my mono blocks over a year ago. I don't have any intention of changing them. Here is a few designs of direct coupled amps.
http://diyaudioprojects.com/Schematics/2A3-Loftin-White-Tube-Amplifier-Schematic.htm
http://www.goodsoundclub.com/Site_Images/J.C. Morrison Micro.jpg

Look these over and tell me how you would change them. I know both are using a power supply that you don't like. I have run a simulation with PSUDII using the 159ZA in LCLC set up.

 

[Opa1]

I guess you sent a email to someone else. I didn't receive a pm either. ? So I'm not sure what you are talking about. My mono blocks are built on 6.5x9 aluminum plates. There isn't a spared inch of room anywhere. I'd rather build a whole new amp than put them under the solder iron.

 

[Opa1]

At the top right of the screen there is a message link to send a PM.(Private Message) You will be able to send all the info there. Don't know who HIFIForum is???

You can also just click on my name. It will send you to my profile. Just click private message there and type. When the message arrives there will be a red box by the message moniker (top right of screen)letting you know you have a message.

 

[TubeHiFiNut]

dowto1000 - you should also see a PM from me on 9/5 welcoming you to the Haven.

 

[dowto1000]

I enjoy your enthusiasm. I also understand your design topology. I built my mono blocks over a year ago. I don't have any intention of changing them. Here is a few designs of direct coupled amps.
http://diyaudioprojects.com/Schematics/2A3-Loftin-White-Tube-Amplifier-Schematic.htm
http://www.goodsoundclub.com/Site_Images/J.C. Morrison Micro.jpg

Look these over and tell me how you would change them. I know both are using a power supply that you don't like. I have run a simulation with PSUDII using the 159ZA in LCLC set up.

Hello Hello opa1!!,


OK, I just ( 10-17-17 ) looked up both. IMHO, neither are good enough to DIY build, a waste of one's time and money.

JC's is marginally better. In the first one, I HATE the added, unnecessary circuit complexity of the SRPP, and in the second one, JC's, I HATE the fact that he chose to parallel the two 6SL7 sections, because paralleling mu of 70 input tubes produces a " choir " effect, and a resultant loss of purity.

On BOTH designs, I deplore the cap input filter after the rectifier, and of course, the high DCR 10 HY chokes in each supply, are the BIGGEST screw - up, its use simply RUINS each amp, both 2A3 amps, from being able to play dynamically.

In either DHT amp, the tube rectifier should see something like this : ( a choke FIRST, never ever a cap ) L1/C1/L2/C2 with the Ls being the 6 Ohm 159ZAs, and the Cs being 40 and 50 uF for C1 and C2, all WIMA films, multiple film cap bypassed. This supply filter I am suggesting, simply ROCKS.

Both amps B+es are too low, at 395 VDC and 400 VDC as the main B+. Each needs about 50 ( to 80 ) more VDC, in their main B+ supply, to optimize the two gain tubes' load lines.

Hey hey hey, we just went, from typical, about the worst, to about the best in a SET DC DHT amp power supply !!

Have fun, be very careful HOW you spend your hobby money, I do !!

Dowto1000