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Preamp tube question


Coytee

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I have a Peach.

 

Looking at the manual, it says it uses three 6DJ8/ECC88 tubes and one 12X4 rectifier.

 

I've had this for nearing 10 years...  thinking it might be due for some new tubes.

 

1.  Is that a fair presumption?

2.  Would you also replace the 12X4 at the same time as the others?

 

I happen to have on hand, three 12AT7's and three 12AX7's.

 

I'm guessing I can NOT use these as replacements

 

Actually, now that I look further, I happen to have a single 6DJ8 spare in hand!  (whoo hoo)

 

The Peach has the high/low Z circuits.  I don't really understand what that means other than one has more OOMPH to maybe drive something at a distance.

 

I think I use the Lo-Z which is the higher output (this stuff always confuses me so pardon if I'm backwards)

 

I'm presuming it's designed so the HiZ circuit uses a single tube (V3 for example?) and the LowZ has a tube dedicated to each channel instead of sharing a tube? (V1 and V2)

 

I'm wondering (if above is true) if I can replace two tubes instead of all three.  If I don't use the HiZ mode and it's a shared tube, why replace it?

 

I do realize I might be misunderstanding all the above....  so open to any thoughts.

 

 

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I'm prolific.... 

 

Reason I'm doing this:  I don't seem to have the raw volume I used to have (same equipment, only difference is speakers are about 45/50 feet away (via wires in walls) than they used to be.

 

When the volume on the Peach gets to 12:00'ish, the system starts to sound saturated in the bass department.  Dial volume back and it doesn't sound as 'blubbery'

 

Active crossover is NOT being over-driven as indicated by the input LED's

 

So, I'm guessing my tubes are getting long in tooth.

 

Now, I have this extra 6DJ8 in my hands.

 

Just got to thinking...  what if I turn system on, turn it up to where it's making me annoyed.

 

Turn system off.  Replace ONE of the current 6DJ8's with the one in hand.  Turn system back on.  Listen to right, then left speaker (since I don't know which tube slot equates to right/left)

 

If a channel "cleans up" relative to the other, then I have my problem.

 

Is that reasonable?

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Yikes...  looking online and I see some of these priced at $50/pair and $600/pair...

 

How critical to the overall sound are these different brands?

 

Is this a place you can cut a corner or is this a place you don't want to cut a corner?

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If you use LoZ, you should get 3 tubes.  All three matching or get one that is really nice and the other two matching.

 

If you use HiZ like I think most the JMA users, get one really nice tube.  Siemens Cca, Tele Cca... both pricey.  I like the Amperex 6922 sound for the money.  I have three of those in a Peach that Really, Really sound good in LoZ.

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HiZ is one tube only.  Low Z will add the additional two tubes for a total of three tube use.  You can match all three if you want ot put a little "nicer" one in V1 and matching "cheaper" ones in V2 and V3.  Or......if you know you will always use LoZ......just go crazy and spend a bunch on all three :)

 

I have the Peach like yours here......with Auricaps (?yours?) and no 6H30.  Got a look-over recently By Craig.

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JC, I think you nailed it. 

 

I had the extra tube.  I had emailed Brent Jesse about getting some replacements...  he said that V1 was probably my problem.  (It was a Mullard brand, something Mark recommended which is why I have this extra tube laying about)

 

I had put the extra tube into one of the other V's....and the sound didn't change substantially...

 

I put it into V1 and it's pretty interesting.

 

When I'm in HiZ mode, it sounds pretty darn good!  (back to speed)  I just lack some of the output to maximize the inputs on the Dx38

 

When I switch to LoZ mode, the blubber is there but as my consolation, I can get further gain into my Dx.... (yay)

 

Jimjimbo has graciously offered me a set that he had extra so I'm buying those.

 

I'll also probably buy a set from Brent when he's back in operation after the Holidays to have a spare set in hand.

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Before was asking about the probability of a tube going south...  I don't recall ever getting any real answers (maybe I missed them)

 

Today was time to put some hands on the situation so I brought it up...tried.

 

My pardon to you if that offended you somehow.

 

 

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