help

[abaloghtesla]

Paul-this is in reply to the upgrade, I finished the shunt regulator. here are my voltage measurements. On metal tab assoc with 1A I get 109.5 v.(110 to 120v) . the second metal tab assoc with 1B, I get 109.0 v(110v to 120v) and with terminal56 I get 128.5 v(130v). With these voltages should I proceed with the rest of the up-grade?        Art

 

[abaloghtesla]

Paul--was not sure if you got my last post---if so, then dis-regard.

 

[Paul Birkeland]

Those seem OK. 

 

[abaloghtesla]

Thanks--Will proceed forward!

 

[abaloghtesla]

Upgrade finished but there was a slight gain in volume but not what I'm looking for.I need some kind of amp that can drive that stereomore to full potential( like PAT 4 driving it). Maybe I'm reaching too far this pre-amp. I'm lost.

 

[Paul Birkeland]

You could put a Moreplay between the Stereomour and the Reduction.

If you had a Stereomour II, there would be another mod or two to increase gain a bit, but gain is pretty high on the Stereomour I already. 

 

[abaloghtesla]

Not to be disrespectful of any who works for Bottlehead, for all you people have given your best, but if I had to build one more kit at this time, I would burst

 

[Paul Joppa]

I went through the whole thread (again), and I downloaded the PAT-4 manual as well - and I am still not 100% confident that we are working the right problem. We have been working a 5-10dB problem but your descriptions seem to indicate a 15-20dB problem. Language is not precise enough to be sure what the real problem is. Here are some questions I still have:

* Is this a Stereomour I or a Stereomour II? Both have appeared in the posts, at different times. (S.II has a balance control; S.I does not.) As PB noted, that makes a difference in what adjustments might be made.

* When you took output from the Reduction to Stereomour to speakers, where did you set the PAT-4 volume control to get an acceptable loudness? Did you use

--1-- turntable to Pat4 phono input, PAT-4 output to Stereomour input, Stereomour output to speakers, or

--2-- turntable to Reduction input, Reduction output to PAT-4 high-level input, PAT-4 output to Stereomour, input, Stereomour output to speakers?

This will help us guess the magnitude of the problem, but if it doesn't help enough there is more that can be done. I am aware that this is getting to be a long slog, but don't lose faith yet!

 

[grufti]

I am confused by this persistent problem. It shouldn't really exist in the first place. Please correct my calculations, if I'm getting this wrong.

OP has a cartridge that is listed as 5.5mV - 5cm/sec. Reduction gain is 36dB @ 1kHz. Stereomour needs 0.4V at the input for full power.

5.5mV * 63V/V = 346.5mV.  The Stereomour is just about 1.25dB below full output with that ... and 5.5mV is by no means the maximum voltage that's ever going to come out of the cartridge. The PAT-4 can't possibly be playing much louder than that through the Stereomour.

Puzzled

 

[abaloghtesla]

Later on today I will hook up my PAT4 to see what my settings are. But I did have it set up to #1---I do have a stereomore 11  Current set up is Fluance turntable with blue cartridge into the reduc tion pre-amp, into the stereomore11 into blumenstein marlin speakers. I have volume control all the way up on stereomore11 and I can sit 3 feet from the speakers and listen to them comfortably. When i use the output of turntable, into PAT4, into stereomore11---yes, Ican pump so music out, that I have to turn down the volume of stereomore11. Right now I just need to hook up everything eliminating the reduction amp and replacing it with the PAT4, and seeing where my controls are placed on both units.

 

[Paul Joppa]

Great! Now, when you find where the controls are set, leave them there and swap in the Reduction - turntable to reduction input, reduction output to PAT-4 high level input (Radio for instance) and see if it is louder or not.

If I read the PAT-4 specs correctly, it should be louder with Reduction. (PAT-4 phono stage is 34dB gain, Reduction with upgrade is 40dB.) If it is louder as expected, then we'll know the Reduction is working correctly and we can interpret the control settings to determine how much more gain you need.

 

[abaloghtesla]

to Paul Joppa: Finally got  to look at my set up. All control knobs are centered. With the reduction in is is a little louder but not that much. I can turn volume control all way max and I still can listen to this record. I can increase volume on PAT4 and I cannot max it,  cause its so loud.

 

[abaloghtesla]

Forget the last sentence or so--it sounded jibber-ish  When the reduction amp is in the ckt with PAT4 , it was louder but not by very much. Not enough to right home about.

 

[abaloghtesla]

Its late now in pittsburgh--I'm signing off.

 

[Paul Joppa]

That's great - I know it's slow but we've made a lot of progress and we're nearly there.

* We knew going in that you need more loudness capability

* We've determined that the Stereomour is able to drive your speakers to adequate loudness, provided it gets enough input signal - so it's worth the effort to look for more gain

* With this last experiment, we've determined that the Reduction is working correctly.

*  We know from the specs that the PAT-4 line section gain is 20dB, and you have reported that it is more than enough - so you need more than zero extra gain, and less than 20dB.

Now we just need to determine how much more gain you need:

With the Reduction in the system with the PAT-4, turn the PAT-4 volume control all the way up. Adjust the volume with the Stereomour control until it's "loud enough", and post back where that volume control is set. It will be more than 12 o'clock (straight up) and less than 5:00 (the maximum). Be as exact as you can - the control is most sensitive between about 12:00 and 2:00 and I expect that's where you will end up.

[Note that I have assumed you have attached the volume knob so that its range is from 5:00 to 11:00, so that 12:00 straight up is exactly the midpoint of the rotation.]

 

[abaloghtesla]

Ok The phono is hooked up to input of reduction and its output is hooked up to Tuner input of PAT4. Volume control of PAT4 is turned fully clockwise. Volume control of stereomore rotates from approx. 7:00 to 5:00 and 12:00 approx. center. As I move  volume  from 7:00 to 9:00 there is as significant increase in volume(very loud) At this point, if I turned the volume contol to midpoint, I would not have any windows in this house.

 

[Paul Joppa]

Well THAT was unexpected!

I must have made an assumption that was not true. I am now wondering whether there might be an issue with the Stereomour volume controls.  Let's try repeating the same test, but with Stereomour volume all the way up, and use the PAT-4 volume control to find the "adequately loud" point. If that falls in the 12:00 to 2:00 range, then there is an issue with the Stereomour after all. If it turns out to be 9:00 then I am perplexed and we'll need to get more methodical, which I have been trying to avoid.

While you're at it, check whether both channels are equally loud with the Stereomour balance control centered, or if you need to set it a little off center.

 

[Paul Birkeland]

Also triple check that you have 12AT7s in the Stereomour and not something else.

 

[abaloghtesla]

Back again: yes I have 12 AT7 in there. I had a little tbl with the left  chan tube on the reduction and after playing with it, I got it to stay on. I re-ckt position of all knobs to see if they were all equi-distant of my marks.Yes, the right chan seems alittle stronger that the left, but by not much ------The second test has same results as first. You start getting comfortable"Tea" music at 0900 and it gets gradually "loud" at 1200 and beyond that, I can audition for Woodstock. Now, I tried it backand forth for at least 5 times and both ways have approx. the same results.

 

[Paul Joppa]

Thanks, that's a help.

You got loud with the Stereomour control at 9:00 and with the PAT-4 at 12:00. Everything I know says they should have been the same, so I suspect you may have switched the tone and balance potentiometers - that would explain the difference. We can check that further by just measuring the input resistance of the Stereomour with the tone control centered and at each extreme. I think this is worth pursuing, just to be sure the amp is working correctly.

But that will have only a small effect on loudness. Everything I know says that the gain of the PAT-4 with the volume set to the midpoint is 1.0, or 0dB. Which says you don't need more gain. But you do! We can pursue that issue by making real gain measurements on both Reduction and Stereomour. Usually PB recommends  using your cellphone as a signal generator, and making voltage measurements at various places including some internal to the amps.

However, it will take a while to get through this exercise. And I completely understand if you need to take a break from this and just get some tunes playing - in which case, you still need some gain, unless you keep the PAT-4 in the circuit.  So I'll suggest that you could purchase an inexpensive preamp to get things going - for example, the Schiit Modi [edit - Magni is what I meant] is a $99 headphone amp that works as a preamp as well, and provides 15dB of gain. I have no direct experience with it, but they are well regarded.

We'll keep working on either or both issues as long as you are wish. We're not going anywhere, so if you want to take a break and pick it up again in a couple months, that's fine too.