Can I reduce gain ?

vinylb · 8615

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Offline vinylb

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on: July 04, 2023, 01:07:24 PM
First of all, thx for such a great kit. It was packed well, had a personal greeting and documentation was top notch that I could easily follow. Test point reference are very useful.

Questions:
1. Would turrets make the build easier?
2. I found the rca sockets little too close together, maybe wider spacing so the ground lugs are not close? This could just be me.
3. I have this hooked up to PS Audio M700 and wow what a great combo except for the gain? I can’t get the pot turned to 9 o’clock before it gets way too loud. Any suggestions?
4. Are these Russian tubes? I bought bunch of variations based on this forum, just surprised how good the stock tubes are.

My setup:
- Rogue Audio RP-1 now taking back seat…..Moreplay in the house
- PS Audio M700 amps
- Maggie’s 1.7i
- Cambridge Audio CXN 2 via Roon
- PS Audio S3 power plant



Offline Paul Birkeland

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Reply #1 on: July 04, 2023, 02:17:12 PM
Turret boards really require very good mechanical connections to be effective, so they aren't such an easy option.  About how many degrees of pot rotation is 9 o'clock for you?  You may find that -20dB Rothwell attenuators plugged into the inputs of your power amp help a lot.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline vinylb

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Reply #2 on: July 04, 2023, 03:22:35 PM
Thank you for your reply.

I have built many 300B amps but never a preamp. What sonic benefits are there to this deal killer Moreplay? Lastly when/what upgrades will be available to Moreplay?



Offline Paul Birkeland

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Reply #3 on: July 05, 2023, 05:13:50 AM
Upgrades are on my to do list, but it's a long list!

The Moreplay is functionally a lot like a basic BeePre 2 but using 6V6s removes the requirement for two quiet filament supplies and lowers the demands from the power transformer, so that part can shrink in size and cost as well.  Preamps like these are ultimately about as simple as they come, and we discovered that these types of preamps could punch way above their weight when first offered this kind of circuit with the Quickie preamp. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Mucker

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Reply #4 on: July 05, 2023, 05:46:28 PM
FWIW, I recently ordered a set of Harrison Labs, 12dB attenuators. This puts the volume indicator at about the 9 o'clock position which is perfectly fine, but more importantly allows me to do low volume listening without having a balance issue. At night I was having a problem when desiring low volume and losing volume in the right speaker compared to the left. I wasn't keen on using the balance knob and instead went the attenuator route. The volume indicator now has adequate travel to negate the balance issue. 12dB is perfectly acceptable for my use and more affordable than the Rothwell.



Offline Doc B.

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Reply #5 on: July 05, 2023, 05:54:50 PM
Quote
I wasn't keen on using the balance knob

?

The low volume setting mismatch of the volume pot is precisely what it's there to address.


Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline vinylb

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Reply #6 on: July 14, 2023, 03:28:25 PM
I did try Harrison Labs 12db attenuators and they definitely did the job, but I felt I lost detail and some liveliness. I wonder if inserting an Lpad would help balance things. Anybody try this?

Thx



Offline Paul Joppa

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Reply #7 on: July 14, 2023, 05:47:59 PM
The Harrison Labs operate at a low 10K impedance, so the 100K Rothwells usually work better with tube gear.

Also the effect is different depending on where they are installed -  at the preamp input vs. the power amp input.

Paul Joppa


Offline Mucker

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Reply #8 on: September 30, 2023, 09:10:03 AM
Just wanted to follow up and mention that after using those Harrison Lab attenuators, I wasn't happy with the sound of them, they just sounded a bit off for whatever reason. And I did try them in different positions.

I read an old post where it was suggested to pad the volume pot using 7.5 and 3.3 kohm resistors. I initially tried with some 1/2W I had on hand. I did have the 7.5 but no 3.3 so ended up with 3 resistors in series to get to 3.3. The result was excellent and I managed to get a much better range of travel on the knob and more importantly the audio was excellent.

So, I then ordered some 2W TKD resistors (less than $10 total) for permanent duty. Yes indeed they are overkill but I do like the meaty look of them. I laughed out loud when they arrived, I didn't realize they were that big.  :-* I also recently installed Jantzen caps and NOS Sylvania 6V6GTY tubes and the Moreplay has never sounded better. It is stellar!

« Last Edit: September 30, 2023, 05:01:51 PM by Mucker »



Offline adeep42

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Reply #9 on: September 30, 2023, 11:23:45 AM
Hi Mucker,

Is that padding the same set up I used to pad down my old Crack with Speedball?



Offline Mucker

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Reply #10 on: September 30, 2023, 03:00:39 PM
Hi,

Yes, it is the exact way, only the resistor values are different. With Moreplay it's 7.5K and 3.3K on the stock pot. Paul showed what to use in this thread:

https://forum.bottlehead.com/index.php?topic=14528.0
« Last Edit: September 30, 2023, 05:03:11 PM by Mucker »