Two rock crs v3 clone and v1 vs v3 differences

[rootz]

Promised a better clip with better audio. Finally had the time to figure out to make 4k video with my Z7 and route the audio from my Mac to it.

Some details about the recording. Dual mic setup. SM57 slightly off axis and close to a EVM12L in an oversized oval back cab. Rode NT1a as a room mic, 1m off axis and 2,5m deep in a 5x3,5m room. Reverb is from the amp, slight delay added to the close mic in Logic Pro. Guitar is a 1986 pre historic Les Paul with Throbak Peter Greens (flipped the magnet to make it stock again).

Since the last recording posted here I changed the Power transformer to one that puts 415V on the plates of the power tubes. That did not make much of a difference to my ears, probably because I adjusted the dropper string to maintain 190V on V1 like before.

Further I made the gnfb adjustable from 4k7 to 10k with a trimmer. It is set to around 8k for this vid I think. Makes for a better match with the small output section than 4k7 to my ears. Came more to life this way.
All signal path resistors are now Dralorics from Jelle. Thanks Jelle!
Dwell pot is now 1megA in series with a 270p mica cap. Less loading on the high end of the signal. A 2meg2 in series with 100p network was added to the voltage divider in front of the 'Tweed mixer" to compensate for some treble loss in comparison with a reverbless #124 (based on LTspice sims, which are generally fairly accurate, especially when comparing circuits).
V1b coupling cap is now 47nF instead of 22n. The 22n moved to the output of the mixer stages and the following master was replaced by a 1megA. Keeps it more inline with #124 with a bit of a Mayor added.

With all that high end added, the amp should sound more like #124, less dark. I suppose the Two Rock CRS3 would be rather dark compared to a real Dumble. Disclaimer: I never heard both in real life, so It's just an (educated) guess.

Well, judge for yourselves. Here is the new vid! Backing track is not mine. Can't remember whose it is, but credits and my thanks go to him/her. Video just for demonstration purposes.

[pompeiisneaks]

That sounds great! I kept thinking it couldn't keep me interested, and damned if you did, I listened through the entire thing going 'yeah!'

Well done, both with the amp and the jammin!

~Phil

[Mr. dB]

And now for some Sunday afternoon guitar torture, a new vid. Not miked up properly, but cam was not clipping or compressing either. Still I think the mids aren't fat enough on the neck. Doesn't really sing when low gain, but might need a lot more volume to achieve that.

Both videos sound nice.

I'm curious, what are the EL34 hifi amps?

[rootz]

Nice isn’t going to cut it I’m still not getting the famous Dumble bloom and feedback thing. Maybe I should just turn it up louder and forget about the neighbours for a couple of minutes. Seriously, how loud should one get before feedback happens? I’m rather positive I’ve got my lead dress right. I’d share gut shots to check on that if anyone can help me with this (would share them anyway).

Those hifi amps are EL34 monoblocks. EF184 long tail pair (two tubes per phase inverter), cascode constant current source on the ltp, schade feedback from the output tubes, Lundahl transformers, Mosfets driving the output tubes (class AB2), Ultra linear. Based on designs from pete millet, SY, gingertube (baby huey) and ideas from George/tubelab on diyaudio.com. Have to dig some further to find the schematic again.

[norburybrook]

Nice isn’t going to cut it I’m still not getting the famous Dumble bloom and feedback thing. Maybe I should just turn it up louder and forget about the neighbours for a couple of minutes. Seriously, how loud should one get before feedback happens? I’m rather positive I’ve got my lead dress right. I’d share gut shots to check on that if anyone can help me with this (would share them anyway).

Those hifi amps are EL34 monoblocks. EF184 long tail pair (two tubes per phase inverter), cascode constant current source on the ltp, schade feedback from the output tubes, Lundahl transformers, Mosfets driving the output tubes (class AB2), Ultra linear. Based on designs from pete millet, SY, gingertube (baby huey) and ideas from George/tubelab on diyaudio.com. Have to dig some further to find the schematic again.

Rootz, you have to have a reasonable amount of level for things to start working properly IMHO. The master volume works very well on these amps but they still sound like they should when you turn them up. The low plate/classic amps need to be louder than high plate/Skyline amps to sound good in my experience. Mt 50W second gen sounds a bit 'flat' until it gets into its stride, then it goes into a lovely OD.

just my 2 cents

M

[Guy77]

Sounds beautiful! Awesome! I am building a similar amp but with higher plate voltages, in the low 400v range. I think yours are in the mid 300v range. I will let you know how it sounds with the higher voltages.

Cheers!

Guy

[Guy77]

Dwell pot is now 1megA in series with a 270p mica cap. Less loading on the high end of the signal. A 2meg2 in series with 100p network was added to the voltage divider in front of the 'Tweed mixer" to compensate for some treble loss in comparison with a reverbless #124 (based on LTspice sims, which are generally fairly accurate, especially when comparing circuits).
V1b coupling cap is now 47nF instead of 22n. The 22n moved to the output of the mixer stages and the following master was replaced by a 1megA. Keeps it more inline with #124 with a bit of a Mayor added.

Hi rootz, you said Dwell pot is 1meg now. Is this the 250K reverb send pot on the back that you changed to 1meg?
Also you mentioned you changed the Master to 1 meg, is this also the 250K Level pot on the back of the amp that was changed to 1meg?

Making your overdrive channel High plate my also help with the feedback.

Thanks !

Guy

[rootz]

A very welcome 2 cents Marcus! Need to find the space and time to turn this amp up and do a similar recording, maybe the next weekend? I dunno. Thanks for confirming I need to turn it up more to get it to really sing. Reminds me of my JTM45 through a reactive load (designed after the 4x12 I use) and really turning it up. The latter was so much better!

[rootz]

Dwell pot is now 1megA in series with a 270p mica cap. Less loading on the high end of the signal. A 2meg2 in series with 100p network was added to the voltage divider in front of the 'Tweed mixer" to compensate for some treble loss in comparison with a reverbless #124 (based on LTspice sims, which are generally fairly accurate, especially when comparing circuits).
V1b coupling cap is now 47nF instead of 22n. The 22n moved to the output of the mixer stages and the following master was replaced by a 1megA. Keeps it more inline with #124 with a bit of a Mayor added.

Hi rootz, you said Dwell pot is 1meg now. Is this the 250K reverb send pot on the back that you changed to 1meg?
Also you mentioned you changed the Master to 1 meg, is this also the 250K Level pot on the back of the amp that was changed to 1meg?

Making your overdrive channel High plate my also help with the feedback.

Thanks !

Guy

Dwell is send, yes. Should change the 270p cap to 470p though. 270p works fine with local fb around the driver, but is not enough in this application. Master I mentioned is the one on the back, so correct again.

This amp will stay low plate classic. I really like this config. It bites, it's raw and pretty in your face, but also smooth and 'nice' enough. Works well for the cover band I play in.

As to plate voltage: I'm getting 415V on the OT centre tap. Bought a new power tranny last month.

[rootz]

More video, now with a Strat. Pretty much a 62 clone, with cheap tone rider pickups. Again low volume home practicing, so not much bloom and feedback happening. Should practice more on my Robben Ford runs, oh well...

[rootz]

And now for some Sunday afternoon guitar torture, a new vid. Not miked up properly, but cam was not clipping or compressing either. Still I think the mids aren't fat enough on the neck. Doesn't really sing when low gain, but might need a lot more volume to achieve that.

Both videos sound nice.

I'm curious, what are the EL34 hifi amps?

I *think* this is the most accurate schematic I have of this amp. Didn't implement the UL/triode switch.

[Guy77]

Thanks for the info rootz! Sounds great!

Guy

[erwin_ve]

You got a great sound with the strat! Turning up treble and setting the presence between 4 and 7 does help the bloom.

[norburybrook]

sounds great Rootz. Nothing wrong with that at all. At gig volumes I'm sure that will open up even more and give you what you're looking for


Nothing wrong with Tonerider pickups. I've used them a lot. In fact I bought a set of boutique PAF's to replace the tonerider humbuckers in a guitar I had. I ended up putting the toneriders back in. They didn't work as well in that particular guitar.

M

[10thTx]

I'd be very happy with an amp that sounded that good! And even happier if I could play that well!

I think your demos sound great!

Thanks for sharing! I hope you'll enjoy the amp and not mod it too much away from the great tone you're already getting.

With respect, 10thtx