miniHRM evolution

[layupe]

Hey Mat awesome sound! Im just amazed since i heard this little amp you managed to build, as others said, having heard so many 5w single ended el84 amps before really become hard to believe how good this one sound! Of course your tasteful playing helps and probably that Gibson of yours plays a role too on the final sound and not to forget the Eminence speaker (im gonna need to start saving for those) but you have created something there and i mean something really impressive!

No need to say this is gonna be my next project and hopefully the one that bring me at last the sound im looking after so just wanted to thank you for sharing this with us

[rogb]

Hey Mat awesome sound! Im just amazed since i heard this little amp you managed to build, as others said, having heard so many 5w single ended el84 amps before really become hard to believe how good this one sound! Of course your tasteful playing helps and probably that Gibson of yours plays a role too on the final sound and not to forget the Eminence speaker (im gonna need to start saving for those) but you have created something there and i mean something really impressive!

No need to say this is gonna be my next project and hopefully the one that bring me at last the sound im looking after so just wanted to thank you for sharing this with us

I think a lot of Mat's tone comes from his great technique, touch and phrasing, not to mention his quality guitars, and would probably sound good plugged into an transistor radio.
I'm going to build the mini HRM EF86, but I ain't gonna sound like him

[mcrracer]

Great Job Mat, I have quickly scanned thru both threads and did not see what I am looking for. Have you or could you post a picture of your front panel controls. I would like to build one of these in a 12" chassis for a small combo amp. The large number of controls just wont let me do this in a small chassis. I was thinking maybe concentric controls as a possible work around. Do you have any suggestions? I might be able to fit five controls but seven I don't know. Thanks

[10thTx]

Just a thought here. Mat uses an internal trimmer for the volume. Could you mount a 500k and 250k 7mm mini-pot on top of each other for the clean channel tone controls?

Or use the 500k mini-pot just for the bass since the bass pot is probably less of a facor with the PAB engaged.

I use a quasi-5E3 tone stack on my OD channels on both D-mutation type amps I have built and I use the 7mm mini-pots & they work fine for me.

With respect, 10thtx

[M Fowler]

10thtx,

I have been wondering the same thing, going with the pots rather then the trimmers.

Mark

[mcrracer]

Just a thought here. Mat uses an internal trimmer for the volume. Could you mount a 500k and 250k 7mm mini-pot on top of each other for the clean channel tone controls?

Or use the 500k mini-pot just for the bass since the bass pot is probably less of a facor with the PAB engaged.

I use a quasi-5E3 tone stack on my OD channels on both D-mutation type amps I have built and I use the 7mm mini-pots & they work fine for me.

With respect, 10thtx

Thanks, I briefly considered the minis but I have not checked my sources for availability. Do you know who carries them?

[10thTx]

Of course Mouser carries them.

However, you can also get them from AES (tubesandmore)

http://www.tubesandmore.com/

I am going to install one in a new build this wkend. It was a previously punched chassis for 6 full sized pots. There is NO room for an additional full size pot.

But I can install the mini-pot in almost the same type space as a DPDT mini-toggle. So a tone control in a switchable OD section will be the quasi 5E3 tone stack. Again, this has worked out successfully for me in several builds.

With respect, 10thtx

[rogb]

Great Job Mat, I have quickly scanned thru both threads and did not see what I am looking for. Have you or could you post a picture of your front panel controls. I would like to build one of these in a 12" chassis for a small combo amp. The large number of controls just wont let me do this in a small chassis. I was thinking maybe concentric controls as a possible work around. Do you have any suggestions? I might be able to fit five controls but seven I don't know. Thanks

http://mattitee.kuvat.fi/kuvat/MTs+miniHRM/DSC_0218.jpg

Can't see that fitting the controls will be a problem. This is Mat's build in a 12" chassis, as he told me. You can always mount the odd control on the back, I guess. Also use straight knobs and mount the pots a little closer?

EDIT: I also wonder if some skilful member could, with the permission/help of Mat and 10thtx and others, put together a TAG style coloured (like Talbany's ones) layout with more detail, I am really struggling with some of the detail on the layout/schematic, mostly because I am fairly inexperienced, not because they aren't done properly
Thanks

[mcrracer]

Great Job Mat, I have quickly scanned thru both threads and did not see what I am looking for. Have you or could you post a picture of your front panel controls. I would like to build one of these in a 12" chassis for a small combo amp. The large number of controls just wont let me do this in a small chassis. I was thinking maybe concentric controls as a possible work around. Do you have any suggestions? I might be able to fit five controls but seven I don't know. Thanks

http://mattitee.kuvat.fi/kuvat/MTs+miniHRM/DSC_0218.jpg

Can't see that fitting the controls will be a problem. This is Mat's build in a 12" chassis, as he told me. You can always mount the odd control on the back, I guess. Also use straight knobs and mount the pots a little closer?

EDIT: I also wonder if some skilful member could, with the permission/help of Mat and 10thtx and others, put together a TAG style coloured (like Talbany's ones) layout with more detail, I am really struggling with some of the detail on the layout/schematic, mostly because I am fairly inexperienced, not because they aren't done properly
Thanks

I am planning a Tweed style combo build with the controls facing up so controls on the back are not an option and seven standard sized pots are not going to fit along with the switches.

[rogb]

Great Job Mat, I have quickly scanned thru both threads and did not see what I am looking for. Have you or could you post a picture of your front panel controls. I would like to build one of these in a 12" chassis for a small combo amp. The large number of controls just wont let me do this in a small chassis. I was thinking maybe concentric controls as a possible work around. Do you have any suggestions? I might be able to fit five controls but seven I don't know. Thanks

http://mattitee.kuvat.fi/kuvat/MTs+miniHRM/DSC_0218.jpg

Can't see that fitting the controls will be a problem. This is Mat's build in a 12" chassis, as he told me. You can always mount the odd control on the back, I guess. Also use straight knobs and mount the pots a little closer?

EDIT: I also wonder if some skilful member could, with the permission/help of Mat and 10thtx and others, put together a TAG style coloured (like Talbany's ones) layout with more detail, I am really struggling with some of the detail on the layout/schematic, mostly because I am fairly inexperienced, not because they aren't done properly
Thanks

I am planning a Tweed style combo build with the controls facing up so controls on the back are not an option and seven standard sized pots are not going to fit along with the switches.

Got it, sounds like the mini pots are a plan then

[azatplayer]

Having trouble locating 20M resistors. Shoud i be looking for certain attributes here? Ive got all metal film Beyshlags for the rest of it.
All i can find locally are the 1/2 watt little demon CC's, or Vishay metal glaze half watts. Never bought a 20 meg resistor b4!

[jelle]

Both should work just fine.

[Structo]

Yeah, 22 Meg is more common.

You could also series two 10 Meg resistors together.

[mat]

Sorry, not much help from me for the control layout design. The present layout of the amp is a mess. I think I will follow 10thTx's layout for the preamp on the next build.

I will use the Ampmakers Power transformer http://www.ampmaker.com/0-190-275v-20w- ... 252-0.html. It has 3 options for the secondary wiring. 0V-190V, 0V-275V and 190V-275V for half, full and 1/10th of power. Anyone have a suggestion how to switch between the tree options on a cathode biased PP 2 x EL84 amp ? The 0-190 and 0-275 options + cathode resistor of the EL84's can be switched with one DPDT but the third option is bit tricky. Any suggestions ?

I have all parts but the chassis for the build. Cannot wait to start/finish (and tweak ) the amp !

[10thTx]

It was pointed out that "Mat's 86 Special layout" and the "86 Special Duet layout" had an error on how the plate cap was hooked up on the EF86.

I corrected both layouts in this thread. However, please compare the schematics with the layouts of each and CHECK for ERRORS!

With respect, 10thtx