First stereo tube amp build advice

[6A3sUMMER]

Usually decoupling is done with RC decoupling.
If the decoupling is not enough, Increase the Capacitance.

If the diode is on sometimes, and off sometimes, that is a Discontinuity.
Discontinuities can cause a step function.
Step functions can cause interference.
Yes?
No?

Think of RC filters as an Integrator. Integrators have a Smoothing effect to any changes.

Electrolytic capacitors of a given capacitance and given voltage rating are smaller than they used to be in decades gone past.

And, if the output tubes cause the B+ to vary quite a lot, I think you need to use more capacitance to supply the output stage.
Solve the problem of the output stage B+, then worry about the earlier stage's and input stage's B+ varying.

Just my 2 cents.

 

[Tom Kamphuys]

6A3sUMMER: Your line of thought seems logical. Losing the diodes also enables me to only use one bleeder resistor.

I've been busy in the mean time with a layout of which I've attached a snapshot. Just an indication to you guys that I'm still working on it; nowhere near finished.

I've also bought and received the book 'Building valve amplifiers' by Morgan Jones. I've skimmed through it and read some interesting parts thoroughly. Very thick and rather wordy, but I still learned more words from Eli

 

[Ketje]

I've also bought and received the book 'Building valve amplifiers' by Morgan Jones. I've skimmed through it and read some interesting parts thoroughly. Very thick and rather wordy, but I still learned more words from Eli

Perhaps you can learn also some (forgotten?) dutch words from this one, free download. https://nvhrbiblio.nl/biblio/boek/hifi_versterker_schakelingen.pdf
Mona

 

[Tom Kamphuys]

Thanks! I found the book in english, but haven't read it yet. I think my contemporary engineering english is better my 1965 engineering dutch. 'kanteelspanning' is a nice example. For those curious what that is, look at the image of a 'kanteel' at the top of the castle tower.

 

[Tom Kamphuys]

I planned my guitar amps in minute detail with a computer, down to component/wire size and colour.

Somehow I keep going round in circles for some time now. So now I'm thinking to start ordering stuff to make it a bit more tangible. Are there any gut shots of an El Cheapo? Or similar amps? That might also help me.

My list of suppliers consists of:
Tonefactory Gitaar en versterkeronderdelen - tonefactory.nl
Tube-Town Store - Tube-Town Store
Musikding Onlineshop für Musikelektronik
Verstarkerrohren und AMP-Zubehor | Tube Amp Doctor
Online-Shop for daka-ware knobs, trafos, shielding sheets, inductors, frontpanels, iec-jacks and more
https://www.ringkerntrafo.nl/index.html
http://www.banzaimusic.com/home.php
https://www.jukebox-revival.eu/

Am I missing any obvious ones near The Netherlands (in the EU)? Also the MJE340 and DN2540N5 seem hard to get. Do any of the large guys (mouser/digikey/...) take orders from private individuals?

 

[Eli Duttman]

Do any of the large guys (mouser/digikey/...) take orders from private individuals?

Yes, they do!

Are there any gut shots of an El Cheapo?

Get in touch with Jeff Yourison, either here or Audio Asylum (AA). Jeff should be able to help you.

 

[oemcar]

Newark also- Think they have warehouses in Europe

 

[OldHector]

I
Do any of the large guys (mouser/digikey/...) take orders from private individuals?

You only need to rustle up an order for €40 or so and it is free delivery. A good way to get higher weight items like Triad chokes from the states.

 

[Tom Kamphuys]

Newark redirects to Farnell for the Netherlands.

Farnell supposedly does not sell to private individuals according some source (attached, in Dutch)

And what about import/customs? I read contradictory statements.

Some Dutch:
Ja: yes
Nee: no
Geen: none
Bedrijfsaccount verplicht: only for businesses
Verzendkosten: shipping fee

 

[Ketje]

Am I missing any obvious ones near The Netherlands (in the EU)? Also the MJE340 and DN2540N5 seem hard to find

Try Security Check or Frag Jan zuerst- Ask Jan first: Roehren und mehr
Mona

 

[JoeAlders]

Thanks Tom for adding that list!

In the recent past I had a similar response from RS Components.
One of the forum members (gerrittube) was so kind to help me out then.

 

[kodabmx]

LCSC ships worldwide. Prices are good. Quality is good. Shipping is expensive but DHL will actually bring you your goods.

Electronic Components Distributor | JLCPCB & EasyEDA Parts Online store - LCSC.COM

 

[Tom Kamphuys]

I've been foolin' around with KiCad. I found a pcb supplier that can also supply parts. I'd rather spent the money on a pcb, than on shipping costs for a handfull of components (MJE340, DN2540N5). Unfortunately it's not El Cheapo: 40,- euro for 6 bias board.

 

[Hearinspace]

Perhaps you can learn also some (forgotten?) dutch words from this one, free download. https://nvhrbiblio.nl/biblio/boek/hifi_versterker_schakelingen.pdf
Mona

Here's the text in English for those who might be interested.

 

[Tom Kamphuys]

I've been playing with KiCad some more. It has a few quirks, but otherwise it is a nice program.

I've made the full audio part of the schematic on pcb, with the exception of grid and screen resistors, diodes and valves. The grid resistors should be close to the sockets. I like the sockets on the chassis. Then it is logical that the diodes are also at the socket. You guys might have noticed I can't make choices and this also enables that. I might replace this pcb for a Baby Huey. The power supply and non-pcb components and wiring should support that I. Using an adapter I might even be able to use EL84's.

However, back to reality: What about the pcb? Any good? Are there any pitfalls? Any advice is welcome.

In the spirit of the El Cheapo: pcb cost is down to 25,- euro for 3 boards (no components)

 

[oemcar]

Nice work!
I've been using Fritzing, but am impressed by your KiCad layouts. Some Fritzing users call it a step up. Will KiCad export RS274 Gerbers for free?

Initially chose Fritzing cuz it would do this without extra charge for Gerber export, like some softwares that advertise RS274 export capability.

3rd pic posted shows 3rd dimensional depth- is that click view option? Or can you rotate axis views?
Jim

 

[Tom Kamphuys]

I think KiCad does that, but I'm not sure. This is the first time I use KiCad and hear about Gerber. The PCB manufacturer I found accepts KiCad files; no need for gerber files (and others?).

The second and third image can be rotated. The second one updates in real time, the third one is a raytraced image that takes some time on my old laptop.

In the mean time I've worked on the pcb some more. I forget some pads that I added and re-arranged some to group them more logically.

 

[Tom Kamphuys]

I think I've captured both the El Cheapo and the Baby Huey on a single pcb. A few resistor values and a solder jumper makes it one or the other.

One thing I'm still wondering about (and haven't included in the pcb): the balance pot in the LTP tail. I read everywhere that the CCS ensures that the LTP is balanced. Is the Baby Huey a special case? Because of its shunt feedback? Does it need the balance pot? For other reasons? ??

 

[Francois G]

Nice work with KiCAD. Makes me want to learn it too!

What schematic for BH EL84 are you looking at. BH does have a LTP balance, certainly in the latest version, dated Nov 19, 2018 (the PCB is R1.6).

 

[Tom Kamphuys]

Hmmmm... I have v1.1, from the wiki. Do you have a link to the latest one?

Edit: Found it: GB for Baby Huey PCB

The Baby Huey has evolved quite a bit....