Achieving a 'Bigger' Sound

[burntfingers]

Hi All,

Thanks for all the information provided here...I've been reading like crazy and learning a lot thanks to this forum.

Please excuse any dumb questions here.

I've recently picked up a C-tone HRM 50 watt. It came with MM transformers. I installed F&T in the filter caps (220uf and 22uf) and lowered the slope to 68k. Other than that it's straight forward. I've playing through an EVM classic.

Here's my challenge (to myself mostly). I recently had a CA OD2 which had a fantastic sound and is in the HRM family as i understand. I'm finding the biggest difference is the 'girth'...er....size of the tone out of that amp compared to this one. I've read that the CA used over-sized transformers in its 50w so i'm sure that has a lot to do with it.

So...with that said. I'm looking to get the biggest sound possible out of this amp. I know the transformers are quality...the filter caps are quality. I've read that the PI circuit could be tweaked to get more size out of it.

Right now the PI coupling caps are the standard 0.1 but I'm wondering if i went the Bluesmaster route with a 0.02 in there would that just muddy the bass?
Also is it safe to just change those caps or do you need to tweak the resistor values as well to get the balance?
Would lowering the mids cap help as well?
Or...is this as big as its going to get and anything else will be just rearranging the deck chairs?


Thanks for any insight!

[erwin_ve]

That's a difficult question to answer. I never heard the CA Od in person.

Did you try the trimpot on the HRM stack? The way I set this is; turn on both OD and Pab, then adjust the HRM trimpots to taste.
Lowering the PI caps to 0.02 cuts bass.
Upping the mid cap to 0.047 works best if your amp sounds congested in the low mids maybe make the slope 100k or 150k again. 68k is more likely used in a Bluesmaster tonestack.

[burntfingers]

Thanks for the reply....I removed the 1n cap from the bass pot and that helped a little.

I’ve dialed in the HRM pots and have a great sound cooking now but it doesn’t have the girth the CA had...I’m thinking the CA’s output transformer has the most to do with that.


The PAB is very thin so I’m going to try the 470k/0.01 trick mentioned here: https://ampgarage.com/forum/viewtopic.p ... r&start=15

[erwin_ve]

Nice! Let me know how the PAB mod works out for you in conjuction with the HRM tonestack. I might do this on one of my own amps. Thanks!

[burntfingers]

I’m thinking about a couple other changes too and wondering if anyone can offer insite:

Switch to EL34’s...apparently this tightens the bass?

Leave the 6L6 and go with 470 screen resistors

[Reeltarded]

Were you playing your previous amp through the same speaker/cab combo?

Here is the thing about transformers. Most of them are "quality" these days.. at least the ones we all use, but what qualities in response? The output matters most if the voltages are in range.. but the power matters as much when the voltages are off the farm.

What is the model of the output tx?

and

Have you verified voltages at every node on the string? Higher voltages can be hard to work around.

34s will lift the bottom response and make it more like a painting of sound than a photo of sound. This isn't your problem though. Your problem is something else. I wonder what specs on the OT are and also about the speaker configuration. There is nothing at all forgiving or elastic about an EV and it can really be hard to get used to, especially if not played pretty hard.

[norburybrook]

. There is nothing at all forgiving or elastic about an EV and it can really be hard to get used to, especially if not played pretty hard.

and that's the bottom line.

A 'Dumble' amp with asn EV speaker will make you get your shit together as a player as it does not for one instance flatter your playing.

This is good thing though.



M