EL84hrm

[10thTx]

I always use ExpressSCH schematics and layouts for my builds because I experiment and tweak so much. The SCH stuff is easily editable for me.

Thought I'd share a layout that I'm considering. I've used paralleled terminals on about 20+ builds with success so I'll probably use that approach when I get around to building this.

I drew this up rather quickly so please check for errors.

4/1/10 EDIT: corrected layout

OK, found another error. V2b cathode cap is 1UF not 5uf.


With respect, 10thtx

[10thTx]

I am not sure what the purpose is of the 22M resistors on the PAB?

Would it be appropriate to use a lower value such as 4.7M resistors in place of the 22M resistors?

With respect, 10thtx

[martin manning]

They are there to prevent popping in the speaker when the switch is thrown. Some circuits I've seen omit them, so you could try that. Reducing the value will reduce the PAB effect.

[CHIP]

I was comparing the EL84 HRM schematic with the ODS 101 HRM schematic and noticed the bass pot jumper leading to the PAB is omitted on the EL84 HRM schematic. Was it over looked?

[Colossal]

I was comparing the EL84 HRM schematic with the ODS 101 HRM schematic and noticed the bass pot jumper leading to the PAB is omitted on the EL84 HRM schematic. Was it over looked?

Excellent catch Chip. Indeed, it was overlooked. I have updated the schematic to include the jumper. Good to have a few sets of eyes for quality control.

Thanks.

[CHIP]

Colossal,
Thank you for sharing.

[Structo]

Sorry but I don't see the change.

[Colossal]

Colossal, thank you for sharing.

You are welcome, but all credit goes to Mat and HiGain for their design.

Sorry but I don't see the change.

Hi Tom, I've attached a drawing that shows the difference (it is subtle, which is why I missed in in the first place! )

[10thTx]

I think I am going to try and build this with a single 5881 to get a little cleaner and louder output. I build the B+ rail to keep the preamp and OD voltages similar to yours but run around 420v on the 5881 plate.

Any thoughts on changes I should be attuned to (or consider) in the preamp or OD section using a 5881 SE? Otherwise I'll just build it and tweak it to taste.

With respect, 10thtx

[mat]

I got the combo ready (the lettering is still missing).

Few pics: http://mattitee.kuvat.fi/kuvat/MTs%20miniHRM/

I did put my (Joe Bonamassa signed ) Gibson ES-339 on the pic so you can see the size of the combo. Bear in mind that 339 is same size as Les Paul.

Soundclip: http://soundclick.com/share?songid=9089004

I like the amp very much. No changes to the circuit made after the last clips. I used two good mics (Sennheiser MD441U3 and AKG C414B-TL II). The AKG has few switches on it. I did not have time to experiment what they do.

[M Fowler]

Sounds great Mat.

[groovtubin]

http://www.myspace.com/omegaamps

Here`s my take on it, sorry for omegaamp theme, throw me out if need be! Its FIRST CLIP

Mat i ran local feedback on the first OD stage. just like a 80`s The drive was TOO much, that brought it in nicely!

respectfully, jim

[M Fowler]

Jim,

So your saying this is your version of the EL84 D amp? Sounded great.

Mark

[groovtubin]

Jim,

So your saying this is your version of the EL84 D amp? Sounded great.

Mark

Hi! Yes it is! Thank you so much! Thats a Traynor YBA-4 convert. Built in loop, local FB on first OD stage, those are NOS EL-84`s, Brimar!! Very FAT! The guy who owns this has (2) of my traynor converts, and i`m getting ramped up to build him a full scale prod amp w/2 X6V6. Just did one ( 6V6) for a guy in Nashville, it`s coming back for a few minor updates. The might EL-84 is a TUFF tube to beat. The cleans are UNREEEL!!!!!!!!!!!!!!!!!!! Fat Sound fell in love w/this amp clip you listened to. I givem my first prod take on 6V6 and he sent me packing! Not anymore! lol!

Have fun! and build MO amps!

jim

[mat]

http://www.myspace.com/omegaamps

Here`s my take on it, sorry for omegaamp theme, throw me out if need be! Its FIRST CLIP

Mat i ran local feedback on the first OD stage. just like a 80`s The drive was TOO much, that brought it in nicely!

respectfully, jim

Sounds really great ! I'll have to try the lfb.