EL34 Baby Huey Amplifier

[rongon]

Well, a choke input psu would then give you a raw B+ of approximately 425*0.9 = 382.5VDC.

Subtract cathode bias of about 22.5V and you have a plate voltage of about 360VDC for the 6L6s.

If you look at the datasheet for 6L6GB or 5881, you'll see that one of the recommended op points for a push-pull class AB1 pair is Vp = 360V, Vsg = 270V, Vg = -22.5V with a 6.6k ohm load (plate-plate). Max plate+screen current is shown as 294mA for two pairs of 6L6.

I see the above in the section for "Class AB1 Push-Pull Amplifier - Pentode Connection" in the Tung Sol 6L6G datasheet:
http://www.r-type.org/pdfs/6l6g.pdf

I'd say the Hammond 300BX looks like it was designed for exactly this usage, with a choke input power supply and solid state rectification.
--

 

[lavane]

Thanks. That's useful info. I'll look at the 300BX data sheet again.

 

[feralmeida]

The Hammond 300BX is rated at 800VCT 288mA. That's plenty of current capacity for a quad of 6L6 tubes. I'd use a big fat choke of about 7H 300mA and make a choke-input power supply (approx +360V). Run the 6L6s at about Va = 350V and Ia = 57mA (20W plate dissipation). That way you can use older 6L6GB or 5881, or run 6L6GC tubes at below their maximum ratings for very long life, or use Russian 6P3S if you like.

Dear Rogon,

Thanks for your help, clarifying my doubts about 6P3C, I have 6K6 toroidy, that point seems better to me than I read about running + B as 6V6 and raising the bias current to 60mA, I don't remember Raa (8 or 10K I suppose) remember about 16 16,5 W.

Google translations are a disaster,
change continuously

 

[lavane]

I'm happy I have finely found a use for that big heavy 300BX I keep stubbing my toe on under my bench.

 

[feralmeida]

I'm happy I have finely found a use for that big heavy 300BX I keep stunning my toe on under my bench.

I also! Thanks to your inquiry, I do not want great powers for my small living room less than 5x4 m

All the best

 

[bandol83]

Hi,

I have made a first tentative for the BOM but there could be still some errors, please check if you find one before to order parts

I am quite busy, but I will try to make the BOM for the power supply soon...

Rgds,
Marc

 

[gingertube]

Is posible to use the 7591a with the bh?

7591a would work well in a Baby Huey amp
UNFORTUNATELY
They have a different pinout to an EL34 so Marcs PCB will NOT suit 7591a

Cheers,
Ian

 

[Bfpca]

6K6 is a good value
the "total" power 30 W is a bit low. <snip>

I am using Toroidy 6600 ohm transformers. With 450v B+ and KT88 you can get over 40w. I found I liked the sound best with 400v and higher bias current. I have a regulated B+ In my amp and can adjust B+. I don’t have a quad of 6l6 but do have 1 pair that I could try to see power output. EL34 gives only slightly less power than KT88 at nominal load impedance but KT88 has a lower output impedance(lower plate resistance) so more power is available into load impedances lower than nominal output tap rating.

I think the Toroidy 6.6 k is rated for 60w and has low series resistances so you get a bit more power out of them than a typical 30w EI transformer.

I am just going to put my BH back into my system in place of 2 100w F5Turbo monoblocks I have been using for a couple of months. I should get a good idea of the BH sound versus the F5s and I’ll try to report what I find. The F5turbo is a tough act to follow IME. These particular ones are biased to 70w class A and will put out 400w into 2 ohms. My speakers are monitor audio gold 300s and they have a minimum impedance of 3.6 ohms so I will use the 4 ohm tap on BH. I’m probably getting somewhere around 35 watts on the BH at 400vB+ into 4 ohms versus over 200 for the F5. I don’t think power output will be an issue though, given the speaker sensitivity of 90db and a smallish room. I don’t seem to use more than 10-20watts peak for most music.

 

[e_fortier]

7591a would work well in a Baby Huey amp
UNFORTUNATELY
They have a different pinout to an EL34 so Marcs PCB will NOT suit 7591a

Cheers,
Ian

Since the pins are not compatible, you could simply make a DIY tube socket adapter, I’ve done many, it’s an easy job.

Here is an example (with other tubes) maybe you could even contact the seller (or other one) and have a few made.

1 × 6V6 To EL84 6BQ5 6P14 Vacuum Tube Amplifier Convert Socket Adapter | eBay

BR
Eric

 

[feralmeida]

On the PCB, there seems to be space to mount elevated sockets (for chassis) with spacers, from there just wiring for 7591A or ................

Regards
Fernan

.....logically carefully, it does not cut any track of the circuit, or a small aluminum plate housing the sockets. (I would like to play a ver. with Philips PE06 40N and 40E (807s 6.3 and 12.6V fils., or NOS 6P14P-ev) In this way, it is not difficult to try 6P1P-EV too, it is part of the fun! ;-)

I have made a first tentative for the BOM but there could be still some errors, please check if you find one before to order parts

I am quite busy, but I will try to make the BOM for the power supply soon...

Rgds,
Marc

I have not seen mistakes, I have little experience, (I have studied the part of the BH story, it is a lot of material ) if Marc has had any confusion, do not put much confidence in me

I'm calmer if someone confirms too

Best Regards
Fernan

 

[gbowling]

I should get a good idea of the BH sound versus the F5s and I’ll try to report what I find.

I look forward to your comparison of these two. I plan on building my EL34 this winter, starting maybe in Jan after the holidays.

Next on my list after that build is an F5T build.

Thanks, gabo

 

[feralmeida]

I decided to finish the 2010 project (audiodesing.com), 50W is a lot of power for me, and I was going to leave it for BH, in the absence of 2 resistance values ​​it is absurd

I have contacted A. Ciuffoli (for a value of 1 that I was missing , it is easy to guess, the use of some component of my stock, does not need to be 100% copied, therefore, less expenses)
have updated on another modification, and confirmed my stock components, they fit very well!

BH, 1 it's a gift, to a dear relative whom I have a lot to thank (I'm excited because I know he will like it, there are help that cannot be measured in money, expect a small NAD to replace your broken amplifier)

I already have a couple of sets Toroidy, and I just received the DC / DC converters, meanwhile, I will prepare the chassis (I am retired, without holidays and all my time is free, which my health allows me).

Then, much more calmly, I will test my modifications with other tubes (for example, PE06 40E and 40N, one channel needs 6.3V and another 12.6V for heaters... and more fun). RE

I will appreciate your impressions of F5T

All the best
Fernan

P.S.
I don't know if you can understand my google translate english well

I found this!

Baby Huey PP EL84 amplifier

For those of us who have less technical knowledge, it is good material to study,
learn and understand well "BH"

 

[DATIR]

hello guys,
I am noob with tubes so i don't have too much knowledge about this but somehow i designed my own PCB for baby huey amplifier the winter is coming ) Still remains to design a pcb for power supply and some delay for HV and after that i will send the gerbers to factory. And i need to continue to do more research about tubes amplifiers This is first revision, still i need to do some optimization.

 

[cgraf]

Hi

While waiting for the MKII Boards of the Baby Huey, I looked a bit around concerning output transformers and wanted to share my findings by supplying a list of manufacturers (rather Europe based) for torodial and classical output transformers.

I will build the amp as two mono blocks. The idea for the moment is to use a toroidal transformer as power tranny, and a EI one as output transformer. But not sure yet.

Here is my list:

German manufacturer, they look nice and are massive:
Ausgangsübertrager, Gegentakt AÜ260, M102a, 6kOhm

German reseller, no idea about the quality but they sell the transformer covers separately:
Frag Jan zuerst- Ask Jan first: Roehren und mehr

German manufacturer. Looks nice but they don't have covers:
Gegentakt-Ausgangsubertrager ATR 55 6.600 Ohm Raa-UL | TBT Trafobau

Italian Manufacturer:
TRASFORMATORE DI USCITA per EL34 PUSH PULL 3400 + Prese / 4 - 8 ohm 50W. Laboratorio Musicale

German Manufacturer:
Welter Audio Electronic                                                                         Seit 1975

Polish manufacturer:
http://ogonowski.eu/transformers/push-pull/lo-pp40-1/

Edcor USA: good prices, shipping to Europe very expensive:
https://www.edcorusa.com/cxpp25-66k

Hammond, available all over Europe
https://eu.mouser.com/ProductDetail/Hammond-Manufacturing/1650N?qs=G4MbTVxgV4F6/29BJF54UQ==

Polish Manufacturer. Very nice chrome covers
https://sklep.toroidy.pl/en_US/p/TT...6,6kOhm-2xEL34-2x6L6-Push-pull-or-similar/562

French Reseller/manufacturer (not sure)
http://www.look-audio.com/contents/fr/d8.html

Italian manufacturer: I know that one of the best sounding amps I listened to is using these:
http://www.teca.net/it/prodotti/valvolare.php

Italian manufacturer with online calculation of the power transformer:
https://autocostruire.com/trasformatori/menubar-en.php


Last but not least an idea for transformer covers, covering the WHOLE transformer
https://it.aliexpress.com/item/32904257198.html?spm=a2g0s.9042311.0.0.6c364c4dSVmdIh


Best regards
Christoph

 

[bandol83]

Hi,

This is a new updated and corrected B.O.M. There was an error with R16, the value was changed to 47k based on Ian (gingertube) recommendation but the manufacturer code was wrong

Please check the list when ordering and let me know if you find other error ?

Au revoir,
Marc

 

[feralmeida]

Thanks

CX1 10nF in BOM, code go to 100nf ( RDER72J104K4M1H03A )

 

[bandol83]

Thanks for your nice observation Fernan (you already found the 47k error)

CX1 is not critical 10 or 100 nF is OK but a minimum of 630 VDC is required ! While checking this point, I have seen that the distance between lead is 10 mm, therefor the following capacitor from EPCOS / TDK will fit the board nicely : B32671P6104K000 ( https://www.mouser.fr/ProductDetail...=sGAEpiMZZMv1cc3ydrPrF7yRxWMKYHonRv/W1fn8GEs= ) but the RDER72J104K4M1H03 will be OK too with a 5 mm between leads

I used a 10 nF 1000 V because I had it in stock...

It is important to check all component size to be sure that they can fit the PCB holes without problem

Cheers,
Marc

 

[feralmeida]

Thanks for your nice observation Fernan (you already found the 47k error)

CX1 is not critical 10 or 100 nF is OK but a minimum of 630 VDC is required !

It is true.
in the BOM I only thought of grouping R6 with R16 :RE
Then it's done!

V Thanks

 

[stonehome]

Well, I am going to add to the available transformers list. Even though I am in the U.S. I have ordered from Menno VanderVeen twice, shipping isn't bad and I usually have the transformers in a couple weeks. Power transformers aren't listed but just list the secondaries required and you will get a quote. All test specifications available also. Very happy with the ones I have.
Push-Pull

Ev

 

[cgraf]

Hi Ev
Thanks for the Menno Van der Veen Site. Did not know it!
Regards
Christoph