The kind of output transformers talked about in this thread are specifically made for valve amps. This design is push-pull so needs push pull output transformers ie they are not "gapped" as they would be for a single ended amp design. Also this design calls for output transformers having ultra linear taps. Ultra linear taps are an extra pair of taps found on the primary winding and are taken from either side of the centre tap to provide feedback to the EL84's.
This design uses a Hammond 1608. Vendors will tell you it has a primary winding impedance of 8k with ul taps and a secondary winding suitable to connect to different speakers, ie 4ohm, 8ohm.
You don't have to use the 1608. As long as your choice of transformer has a primary impedance of around +/- 10% of 8k. I used the Hammond 1609 (primary impedance 10k) and I think sounds great. Edcor OT's would be another alternative.
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The ECC83's/12ax7's are pin compatible with the ECC803S and IMHO consider them to be close enough electrically to be a substitute for the ECC803S.
I started off using the JJ ECC803S as used (IIRC) in Ian's original build which I liked but had nothing to compare them with. I then bought a pair of Sovtek 12ax7lps's off of Ebay and liked these also. I then got some Mullard ECC83'S and liked these too. ( Perhaps you can see where I'm going here ) Currently I'm using a pair of Telefunkin ECC83's which I like most of all. I dream of auditioning a pair of original Telefunkin ECC803S's......
Despite the apparent sound differences detected between the various manufacturers of ECC83's/12ax7's and the JJ ECC803S I believe the quality of the output transformer has a greater influence on sound reproduction.
Hello Hylle,
Not lost interest, just happily using their amps after going through the build process!
Mine is a fixed-bias EL84 which uses the MOSFET sourcefollowers. No need for heatsinks as they pass only a few mA.
The amp is designed to be used as an "integrated" by adding a pot, as you guessed.
Rod
Not lost interest, just happily using their amps after going through the build process!
Mine is a fixed-bias EL84 which uses the MOSFET sourcefollowers. No need for heatsinks as they pass only a few mA.
The amp is designed to be used as an "integrated" by adding a pot, as you guessed.
Rod
This may be bad form... if so, I won't be offended if the response is 'look it up yourself'... but it would be really helpful if we had a summary posting with links or post numbers to the "best-and-final" designs (schematics) for the Baby Huey. I have tried to keep up with the variants along the way, but have lost focus. It's an age thing for me
It's just taking me a while to get around to the build.
Cheers,
Ryan
It's just taking me a while to get around to the build.
Cheers,
Ryan
Well there is the DIY AUDIO wiki. Which has some stuff. But they are all variations on the "basic" one.
Baby Huey PP EL84 amplifier - diyAudio
Baby Huey PP EL84 amplifier - diyAudio
Hi everyone
I like to share with you my creation of the Baby Huey.
This was made as part of the TubeSociety a course for building and designing valve amp's given by Menno vd Veen.
In this design i wanted to have some extra power there fore i put an extra set of EL84 tube's in the amp.
A part of this extra power is used to create some extra local feedback by increasing the resistor in the middle i have used 50K for this one.
http://www.diyaudio.com/forums/attachment.php?attachmentid=320640&stc=1&d=1356974775
And this is how it looks like.
Regards George
I like to share with you my creation of the Baby Huey.
This was made as part of the TubeSociety a course for building and designing valve amp's given by Menno vd Veen.
In this design i wanted to have some extra power there fore i put an extra set of EL84 tube's in the amp.
A part of this extra power is used to create some extra local feedback by increasing the resistor in the middle i have used 50K for this one.
http://www.diyaudio.com/forums/attachment.php?attachmentid=320640&stc=1&d=1356974775
And this is how it looks like.
Regards George
Attachments
Strange PSU noise?!
Hi all,
I've been slowly building up my 6F6 version of the baby huey and today was the first time of fired up the PSU (no tubes or signal circuits connected). All voltages were as they should be but there was a strange buzzing noise coming from the circuit board. It sounded like a high voltage electrical discharge that varied as I changed the mains voltage with my variac....
The next hour or so was spend de-construction the PSU until I was left with only the basic HV diodes, subbers, CLC and bleed resistor...still the noise remained. Eventually I removed the 10nf snubbers that are across the HV diodes and hey presto problem fixed!
I've never come across this noise before and am at a loss as to what is happening. Can anyone help me understand what is happening with the snubbers? These are ceramic 10nf 3KV caps and the HV diodes are IXYS FRED 1200V 11A TO-220's.
Thanks in advance...
Hi all,
I've been slowly building up my 6F6 version of the baby huey and today was the first time of fired up the PSU (no tubes or signal circuits connected). All voltages were as they should be but there was a strange buzzing noise coming from the circuit board. It sounded like a high voltage electrical discharge that varied as I changed the mains voltage with my variac....
The next hour or so was spend de-construction the PSU until I was left with only the basic HV diodes, subbers, CLC and bleed resistor...still the noise remained. Eventually I removed the 10nf snubbers that are across the HV diodes and hey presto problem fixed!
I've never come across this noise before and am at a loss as to what is happening.
Can anyone help me understand what is happening with the snubbers? These are ceramic 10nf 3KV caps and the HV diodes are IXYS FRED 1200V 11A TO-220's.Thanks in advance...
I'm yet another person (newbie) embarking on building a Baby Huey and have already ordered the output-transformers (MQ565) from Magnequest. These have the UL taps. I'm at the point of reading and re-reading many of the posts in this thread as for components needed
I wish to build the power supply seen on post #1287 and was wondering on the value of the choke. Am I correct in assuming that I could use the LL1673 (2.5 - 20 H) for this purpose?
http://www.lundahl.se/pdfs/datash/1673.pdf
If I correctly understand the choke pdf shown above, I can wire the choke to get different values. Would 5H be appropriate for this power supply in post #1287?
Cheers
Frank M
I wish to build the power supply seen on post #1287 and was wondering on the value of the choke. Am I correct in assuming that I could use the LL1673 (2.5 - 20 H) for this purpose?
http://www.lundahl.se/pdfs/datash/1673.pdf
If I correctly understand the choke pdf shown above, I can wire the choke to get different values. Would 5H be appropriate for this power supply in post #1287?
Cheers
Frank M
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